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Exploring the Quantum Universe: Pathways to Innovation and Discovery in Particle Physics
Authors:
Shoji Asai,
Amalia Ballarino,
Tulika Bose,
Kyle Cranmer,
Francis-Yan Cyr-Racine,
Sarah Demers,
Cameron Geddes,
Yuri Gershtein,
Karsten Heeger,
Beate Heinemann,
JoAnne Hewett,
Patrick Huber,
Kendall Mahn,
Rachel Mandelbaum,
Jelena Maricic,
Petra Merkel,
Christopher Monahan,
Hitoshi Murayama,
Peter Onyisi,
Mark Palmer,
Tor Raubenheimer,
Mayly Sanchez,
Richard Schnee,
Sally Seidel,
Seon-Hee Seo
, et al. (7 additional authors not shown)
Abstract:
This is the report from the 2023 Particle Physics Project Prioritization Panel (P5) approved by High Energy Physics Advisory Panel (HEPAP) on December 8, 2023. The final version was made public on May 8, 2024 and submitted to DOE SC and NSF MPS.
This is the report from the 2023 Particle Physics Project Prioritization Panel (P5) approved by High Energy Physics Advisory Panel (HEPAP) on December 8, 2023. The final version was made public on May 8, 2024 and submitted to DOE SC and NSF MPS.
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Submitted 27 July, 2024;
originally announced July 2024.
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Dark Matter Freeze Out with Tsallis Statistics in the Early Universe
Authors:
Thomas D. Rueter,
Thomas G. Rizzo,
JoAnne L. Hewett
Abstract:
The nature of dark matter (DM) and how it might interact with the particles of the Standard Model (SM) is one of greatest mysteries currently facing particle physics, and addressing these issues should provide some understanding of how the observed relic abundance was produced. One widely considered production mechanism, a weakly interacting massive particle (WIMP) produced as a thermal relic, pro…
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The nature of dark matter (DM) and how it might interact with the particles of the Standard Model (SM) is one of greatest mysteries currently facing particle physics, and addressing these issues should provide some understanding of how the observed relic abundance was produced. One widely considered production mechanism, a weakly interacting massive particle (WIMP) produced as a thermal relic, provides a target cross section for DM annihilation into SM particles by solving the Boltzmann equation. In this thermal freeze-out mechanism, dark matter is produced in thermal equilibrium with the SM in the early universe, and drops out of equilibrium to its observed abundance as the universe cools and expands. In this paper, we study the impact of a generalized thermodynamics, known as Tsallis statistics and governed by a parameter $q$, on the target DM annihilation cross section. We derive the phase space distributions of particles in this generalized statistical framework, and check their thermodynamic consistency, as well as analyzing the impact of this generalization on the collisional term of the Boltzmann equation. We consider the case of an initial value of $q_0>1$, with $q$ relaxing to 1 as the universe expands and cools, and solve the generalized Boltzmann numerically for several benchmark DM masses, finding the corresponding target annihilation cross sections as a function of $q_0$. We find that as $q$ departs from the standard thermodynamic case of $q=1$, the collisional term falls less slowly as a function of $x = m_χ/T$ than expected in the standard case. We also find that the target cross section falls sharply from $σv \simeq 2.2-2.6\times10^{-26} \textrm{cm}^3/\textrm{s}$ for $q_0=1$ to, for example, $σv \simeq 3\times 10^{-34} \textrm{cm}^3/\textrm{s}$ for $q_0=1.05$ for a 100 GeV WIMP.
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Submitted 14 October, 2020; v1 submitted 25 November, 2019;
originally announced November 2019.
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Les Houches 2017: Physics at TeV Colliders New Physics Working Group Report
Authors:
G. Brooijmans,
M. Dolan,
S. Gori,
F. Maltoni,
M. McCullough,
P. Musella,
L. Perrozzi,
P. Richardson,
F. Riva,
A. Angelescu,
S. Banerjee,
D. Barducci,
G. Bélanger,
B. Bhattacherjee,
M. Borsato,
A. Buckley,
J. M. Butterworth,
G. Cacciapaglia,
H. Cai,
A. Carvalho,
A. Chakraborty,
G. Cottin,
A. Deandrea,
J. de Blas,
N. Desai
, et al. (58 additional authors not shown)
Abstract:
We present the activities of the `New Physics' working group for the `Physics at TeV Colliders' workshop (Les Houches, France, 5--23 June, 2017). Our report includes new physics studies connected with the Higgs boson and its properties, direct search strategies, reinterpretation of the LHC results in the building of viable models and new computational tool developments.
We present the activities of the `New Physics' working group for the `Physics at TeV Colliders' workshop (Les Houches, France, 5--23 June, 2017). Our report includes new physics studies connected with the Higgs boson and its properties, direct search strategies, reinterpretation of the LHC results in the building of viable models and new computational tool developments.
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Submitted 27 March, 2018;
originally announced March 2018.
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Ghosts- and Tachyon-Free Regions of the Randall-Sundrum Model Parameter Space
Authors:
George N. Wojcik,
JoAnne L. Hewett,
Thomas G. Rizzo
Abstract:
Model building within the Randall-Sundrum (RS) framework generally involves placing the Standard Model fields in the bulk. Such fields may possess non-zero values for their associated brane-localized kinetic terms (BLKTs) in addition to possible bulk mass parameters. In this paper we clearly identify the regions of the RS model parameter space where the presence of bulk mass terms and BLKTs yield…
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Model building within the Randall-Sundrum (RS) framework generally involves placing the Standard Model fields in the bulk. Such fields may possess non-zero values for their associated brane-localized kinetic terms (BLKTs) in addition to possible bulk mass parameters. In this paper we clearly identify the regions of the RS model parameter space where the presence of bulk mass terms and BLKTs yield a setup which is free from both ghost and tachyon instabilities. Such physically acceptable parameter space regions can then be used to construct realistic and phenomenologically viable RS models.
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Submitted 26 February, 2018; v1 submitted 15 February, 2018;
originally announced February 2018.
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US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report
Authors:
Marco Battaglieri,
Alberto Belloni,
Aaron Chou,
Priscilla Cushman,
Bertrand Echenard,
Rouven Essig,
Juan Estrada,
Jonathan L. Feng,
Brenna Flaugher,
Patrick J. Fox,
Peter Graham,
Carter Hall,
Roni Harnik,
JoAnne Hewett,
Joseph Incandela,
Eder Izaguirre,
Daniel McKinsey,
Matthew Pyle,
Natalie Roe,
Gray Rybka,
Pierre Sikivie,
Tim M. P. Tait,
Natalia Toro,
Richard Van De Water,
Neal Weiner
, et al. (226 additional authors not shown)
Abstract:
This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.
This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.
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Submitted 14 July, 2017;
originally announced July 2017.
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Gravity-Mediated Dark Matter Annihilation in the Randall-Sundrum Model
Authors:
Thomas D. Rueter,
Thomas G. Rizzo,
JoAnne L. Hewett
Abstract:
Observational evidence for dark matter stems from its gravitational interactions, and as of yet there has been no evidence for dark matter interacting via other means. We examine models where dark matter interactions are purely gravitational in a Randall-Sundrum background. In particular, the Kaluza-Klein tower of gravitons which result from the warped fifth dimension can provide viable annihilati…
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Observational evidence for dark matter stems from its gravitational interactions, and as of yet there has been no evidence for dark matter interacting via other means. We examine models where dark matter interactions are purely gravitational in a Randall-Sundrum background. In particular, the Kaluza-Klein tower of gravitons which result from the warped fifth dimension can provide viable annihilation channels into Standard Model final states, and we find that we can achieve values of the annihilation cross section, $\left< σv \right>$, which are consistent with the observed relic abundance in the case of spin-1 dark matter. We examine constraints on these models employing both the current photon line and continuum indirect dark matter searches, and assess the prospects of hunting for the signals of such models in future direct and indirect detection experiments.
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Submitted 12 October, 2017; v1 submitted 22 June, 2017;
originally announced June 2017.
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Dark Sectors 2016 Workshop: Community Report
Authors:
Jim Alexander,
Marco Battaglieri,
Bertrand Echenard,
Rouven Essig,
Matthew Graham,
Eder Izaguirre,
John Jaros,
Gordan Krnjaic,
Jeremy Mardon,
David Morrissey,
Tim Nelson,
Maxim Perelstein,
Matt Pyle,
Adam Ritz,
Philip Schuster,
Brian Shuve,
Natalia Toro,
Richard G Van De Water,
Daniel Akerib,
Haipeng An,
Konrad Aniol,
Isaac J. Arnquist,
David M. Asner,
Henning O. Back,
Keith Baker
, et al. (179 additional authors not shown)
Abstract:
This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years.
This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years.
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Submitted 30 August, 2016;
originally announced August 2016.
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Complementarity of Resonant Scalar, Vector-Like Quark and Superpartner Searches in Elucidating New Phenomena
Authors:
Anke Biekötter,
JoAnne L. Hewett,
Jong Soo Kim,
Michael Krämer,
Thomas G. Rizzo,
Krzysztof Rolbiecki,
Jamie Tattersall,
Torsten Weber
Abstract:
The elucidation of the nature of new phenomena requires a multi-pronged approach to understand the essential physics that underlies it. As an example, we study the simplified model containing a new scalar singlet accompanied by vector-like quarks, as motivated by the recent diphoton excess at the LHC. To be specific, we investigate three models with $SU(2)_L$-doublet, vector-like quarks with Yukaw…
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The elucidation of the nature of new phenomena requires a multi-pronged approach to understand the essential physics that underlies it. As an example, we study the simplified model containing a new scalar singlet accompanied by vector-like quarks, as motivated by the recent diphoton excess at the LHC. To be specific, we investigate three models with $SU(2)_L$-doublet, vector-like quarks with Yukawa couplings to a new scalar singlet and which also couple off-diagonally to corresponding Standard Model fermions of the first or third generation through the usual Higgs boson. We demonstrate that three classes of searches can play important and complementary roles in constraining this model. In particular, we find that missing energy searches designed for superparticle production, supply superior sensitivity for vector-like quarks than the dedicated new quark searches themselves.
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Submitted 29 August, 2016; v1 submitted 3 August, 2016;
originally announced August 2016.
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Les Houches 2015: Physics at TeV colliders - new physics working group report
Authors:
G. Brooijmans,
C. Delaunay,
A. Delgado,
C. Englert,
A. Falkowski,
B. Fuks,
S. Nikitenko,
S. Sekmen,
D. Barducci,
J. Bernon,
A. Bharucha,
J. Brehmer,
I. Brivio,
A. Buckley,
D. Burns,
G. Cacciapaglia,
H. Cai,
A. Carmona,
A. Carvalho,
G. Chalons,
Y. Chen,
R. S. Chivukula,
E. Conte,
A. Deandrea,
N. De Filippis
, et al. (56 additional authors not shown)
Abstract:
We present the activities of the 'New Physics' working group for the 'Physics at TeV Colliders' workshop (Les Houches, France, 1-19 June, 2015). Our report includes new physics studies connected with the Higgs boson and its properties, direct search strategies, reinterpretation of the LHC results in the building of viable models and new computational tool developments. Important signatures for sea…
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We present the activities of the 'New Physics' working group for the 'Physics at TeV Colliders' workshop (Les Houches, France, 1-19 June, 2015). Our report includes new physics studies connected with the Higgs boson and its properties, direct search strategies, reinterpretation of the LHC results in the building of viable models and new computational tool developments. Important signatures for searches for natural new physics at the LHC and new assessments of the interplay between direct dark matter searches and the LHC are also considered.
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Submitted 9 May, 2016;
originally announced May 2016.
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750 GeV Diphoton Resonance in Warped Geometries
Authors:
JoAnne L. Hewett,
Thomas G. Rizzo
Abstract:
We examine the scenario of a warped extra dimension containing bulk SM fields in light of the observed diphoton excess at 750 GeV. We demonstrate that a spin-2 graviton whose action contains localized kinetic brane terms for both gravity and gauge fields is compatible with the excess, while being consistent with all other constraints. The graviton sector of this model contains a single free parame…
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We examine the scenario of a warped extra dimension containing bulk SM fields in light of the observed diphoton excess at 750 GeV. We demonstrate that a spin-2 graviton whose action contains localized kinetic brane terms for both gravity and gauge fields is compatible with the excess, while being consistent with all other constraints. The graviton sector of this model contains a single free parameter, once the mass of the graviton is fixed. The scale of physics on the IR-brane is found to lie in the range of a $\sim$ few TeV, relevant to the gauge hierarchy. There remains significant flexibility in the coupled gauge/fermion KK sectors to address the strong constraints arising from precision measurements.
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Submitted 16 August, 2016; v1 submitted 27 March, 2016;
originally announced March 2016.
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Simplified Models for Higgs Physics: Singlet Scalar and Vector-like Quark Phenomenology
Authors:
Matthew J. Dolan,
J. L. Hewett,
M. Krämer,
T. G. Rizzo
Abstract:
Simplified models provide a useful tool to conduct the search and exploration of physics beyond the Standard Model in a model-independent fashion. In this work we consider the complementarity of indirect searches for new physics in Higgs couplings and distributions with direct searches for new particles, using a simplified model which includes a new singlet scalar resonance and vector-like fermion…
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Simplified models provide a useful tool to conduct the search and exploration of physics beyond the Standard Model in a model-independent fashion. In this work we consider the complementarity of indirect searches for new physics in Higgs couplings and distributions with direct searches for new particles, using a simplified model which includes a new singlet scalar resonance and vector-like fermions that can mix with the SM top-quark. We fit this model to the combined ATLAS and CMS 125 GeV Higgs production and coupling measurements and other precision electroweak constraints, and explore in detail the effects of the new matter content upon Higgs production and kinematics. We highlight some novel features and decay modes of the top partner phenomenology, and discuss prospects for Run II.
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Submitted 26 January, 2016;
originally announced January 2016.
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The Diboson Excess: Experimental Situation and Classification of Explanations; A Les Houches Pre-Proceeding
Authors:
Johann Brehmer,
Gustaaf Brooijmans,
Giacomo Cacciapaglia,
Adrian Carmona,
Sekhar R. Chivukula,
Antonio Delgado,
Florian Goertz,
JoAnne L. Hewett,
Andrey Katz,
Joachim Kopp,
Kenneth Lane,
Adam Martin,
Kirtimaan Mohan,
David M. Morse,
Marco Nardecchia,
Jose Miguel No,
Alexandra Oliveira,
Chris Pollard,
Mariano Quiros,
Thomas G. Rizzo,
Jose Santiago,
Veronica Sanz,
Elizabeth H. Simmons,
Jamie Tattersall
Abstract:
We examine the `diboson' excess at $\sim 2$ TeV seen by the LHC experiments in various channels. We provide a comparison of the excess significances as a function of the mass of the tentative resonance and give the signal cross sections needed to explain the excesses. We also present a survey of available theoretical explanations of the resonance, classified in three main approaches. Beyond that,…
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We examine the `diboson' excess at $\sim 2$ TeV seen by the LHC experiments in various channels. We provide a comparison of the excess significances as a function of the mass of the tentative resonance and give the signal cross sections needed to explain the excesses. We also present a survey of available theoretical explanations of the resonance, classified in three main approaches. Beyond that, we discuss methods to verify the anomaly, determining the major properties of the various surpluses and exploring how different models can be discriminated. Finally, we give a tabular summary of the numerous explanations, presenting their main phenomenological features.
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Submitted 14 December, 2015;
originally announced December 2015.
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The CP-Violating pMSSM
Authors:
Joshua Berger,
Matthew W. Cahill-Rowley,
Diptimoy Ghosh,
JoAnne L. Hewett,
Ahmed Ismail,
Thomas G. Rizzo
Abstract:
We investigate the sensitivity of the next generation of flavor-based low-energy experiments to probe the supersymmetric parameter space in the context of the phenomenological MSSM (pMSSM), and examine the complementarity with direct searches for Supersymmetry at the 13 TeV LHC in a quantitative manner. To this end, we enlarge the previously studied pMSSM parameter space to include all physical no…
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We investigate the sensitivity of the next generation of flavor-based low-energy experiments to probe the supersymmetric parameter space in the context of the phenomenological MSSM (pMSSM), and examine the complementarity with direct searches for Supersymmetry at the 13 TeV LHC in a quantitative manner. To this end, we enlarge the previously studied pMSSM parameter space to include all physical non-zero CP-violating phases, namely those associated with the gaugino mass parameters, Higgsino mass parameter, and the tri-linear couplings of the top quark, bottom quark and tau lepton. We find that future electric dipole moment and flavor measurements can have a strong impact on the viability of these models even if the sparticle spectrum is out of reach of the 13 TeV LHC. In particular, the lack of positive signals in future low-energy probes would exclude values of the phases between ${\cal O}(10^{-2})$ and ${\cal O}(10^{-1})$. We also find regions of parameter space where large phases remain allowed due to cancellations. Most interestingly, in some rare processes, such as BR($B_s \to μ^+ μ^-$ ), we find that contributions arising from CP-violating phases can bring the potentially large SUSY contributions into better agreement with experiment and Standard Model predictions.
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Submitted 15 January, 2016; v1 submitted 29 October, 2015;
originally announced October 2015.
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Symmetry Restored in Dibosons at the LHC?
Authors:
Johann Brehmer,
JoAnne Hewett,
Joachim Kopp,
Thomas Rizzo,
Jamie Tattersall
Abstract:
A number of LHC resonance search channels display an excess in the invariant mass region of 1.8 - 2.0 TeV. Among them is a $3.4\,σ$ excess in the fully hadronic decay of a pair of Standard Model electroweak gauge bosons, in addition to potential signals in the $HW$ and dijet final states. We perform a model-independent cross-section fit to the results of all ATLAS and CMS searches sensitive to the…
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A number of LHC resonance search channels display an excess in the invariant mass region of 1.8 - 2.0 TeV. Among them is a $3.4\,σ$ excess in the fully hadronic decay of a pair of Standard Model electroweak gauge bosons, in addition to potential signals in the $HW$ and dijet final states. We perform a model-independent cross-section fit to the results of all ATLAS and CMS searches sensitive to these final states. We then interpret these results in the context of the Left-Right Symmetric Model, based on the extended gauge group $SU(2)_L\times SU(2)_R\times U(1)'$, and show that a heavy right-handed gauge boson $W_R$ can naturally explain the current measurements with just a single coupling $g_R \sim 0.4$. In addition, we discuss a possible connection to dark matter.
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Submitted 12 November, 2015; v1 submitted 30 June, 2015;
originally announced July 2015.
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The ATLAS Z + MET Excess in the MSSM
Authors:
M. Cahill-Rowley,
J. L. Hewett,
A. Ismail,
T. G. Rizzo
Abstract:
We demonstrate that the $3σ$ excess observed by ATLAS in the Z + MET channel can be explained within the context of the MSSM. Using the freedom inherent in the pMSSM, we perform a detailed analysis of the parameter space and find a scenario that describes the excess while simultaneously complying with all other search constraints from the Run I data at 7 and 8 TeV, including the Z + MET analysis b…
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We demonstrate that the $3σ$ excess observed by ATLAS in the Z + MET channel can be explained within the context of the MSSM. Using the freedom inherent in the pMSSM, we perform a detailed analysis of the parameter space and find a scenario that describes the excess while simultaneously complying with all other search constraints from the Run I data at 7 and 8 TeV, including the Z + MET analysis by CMS. We generate a small sample of simplified models, using promising models from our existing pMSSM sample as seeds, and study their properties. The successful region is described by the production of 1st/2nd generation squark pairs, followed by their decay into a bino-like neutralino which in turn decays into a Higgsino-like LSP triplet by emitting a Z boson, i.e., $\tilde q\to\tilde B\to\tilde h$ with $\tilde q = \tilde Q_L,\tilde u_R,$ or $\tilde d_R$. The sweet spot for the sparticle spectrum is found to have squark masses in the 500-750 GeV range, with bino masses near 350 GeV with a mass splitting of 150-200 GeV with the Higgsino LSP. If this excess holds, then this scenario predicts that a signal will be observed in the 0l + jets and/or 1l + jets searches in the early operations of Run II.
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Submitted 18 June, 2015;
originally announced June 2015.
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Towards a Supersymmetric Description of the Fermi Galactic Center Excess
Authors:
Matthew Cahill-Rowley,
Jamie Gainer,
JoAnne Hewett,
Tom Rizzo
Abstract:
We attempt to build a model that describes the {\it Fermi} galactic gamma-ray excess (FGCE) within a UV-complete Supersymmetric framework; we find this to be highly non-trivial. At the very least a successful Supersymmetric explanation must have several important ingredients in order to fit the data and satisfy other theoretical and experimental constraints. Under the assumption that a {\it single…
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We attempt to build a model that describes the {\it Fermi} galactic gamma-ray excess (FGCE) within a UV-complete Supersymmetric framework; we find this to be highly non-trivial. At the very least a successful Supersymmetric explanation must have several important ingredients in order to fit the data and satisfy other theoretical and experimental constraints. Under the assumption that a {\it single} annihilation mediator is responsible for both the observed relic density as well as the FGCE, we show that the requirements are not easily satisfied in many TeV-scale SUSY models, but can be met with some model building effort in the general NMSSM with $\sim 10$ parameters beyond the MSSM. We find that the data selects a particular region of the parameter space with a mostly singlino lightest Supersymmetric particle and a relatively light CP-odd Higgs boson that acts as the mediator for dark matter annihilation. We study the predictions for various observables within this parameter space, and find that searches for this light CP-odd state at the LHC, as well as searches for the direct detection of dark matter, are likely to be quite challenging. It is possible that a signature could be observed in the flavor sector; however, indirect detection remains the best probe of this scenario.
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Submitted 3 March, 2015; v1 submitted 4 September, 2014;
originally announced September 2014.
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Higgs Coupling Measurements and Direct Searches as Complementary Probes of the pMSSM
Authors:
M. Cahill-Rowley,
J. Hewett,
A. Ismail,
T. Rizzo
Abstract:
The parameter space of the MSSM can be probed via many avenues, such as by pre- cision measurements of the couplings of the ~126 GeV Higgs boson, as well as the direct searches for SUSY partners. We examine the connection between these two collider observables at the LHC and ILC in the 19/20-parameter p(henomenological)MSSM. Within this scenario, we address two questions: (i) How will potentially…
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The parameter space of the MSSM can be probed via many avenues, such as by pre- cision measurements of the couplings of the ~126 GeV Higgs boson, as well as the direct searches for SUSY partners. We examine the connection between these two collider observables at the LHC and ILC in the 19/20-parameter p(henomenological)MSSM. Within this scenario, we address two questions: (i) How will potentially null direct searches for SUSY at the LHC influence the predicted properties of the lightest SUSY Higgs boson? (ii) What can be learned about the properties of the superpartners from precision measurements of the Higgs boson couplings? In this paper, we examine these questions by employing three different large sets of pMSSM models with either the neutralino or gravitino being the LSP. We make use of the ATLAS direct SUSY searches at the 7/8 TeV LHC as well as expected results from 14 TeV operations, and the anticipated precision measurements of the Higgs Boson couplings at the 14 TeV LHC and at the ILC. We demonstrate that the future Higgs coupling determinations can deeply probe the pMSSM parameter space and, in particular, can observe the effects of models that are projected to evade the direct searches at the 14 TeV LHC with 3 inverse ab of integrated luminosity. In addition, we compare the reach of the Higgs coupling determinations to the direct heavy Higgs searches in the MA - tan beta plane and show that they cover orthogonal regions. This analysis demonstrates the complementarity of the direct and indirect approaches in searching for Supersymmetry, and the importance of precision studies of the properties of the Higgs Boson.
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Submitted 25 July, 2014;
originally announced July 2014.
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Lessons and Prospects from the pMSSM after LHC Run I: Neutralino LSP
Authors:
M. Cahill-Rowley,
J. L. Hewett,
A. Ismail,
T. G. Rizzo
Abstract:
We study SUSY signatures at the 7, 8 and 14 TeV LHC employing the 19-parameter, R-Parity conserving p(henomenological)MSSM, in the scenario with a neutralino LSP. Our results were obtained via a fast Monte Carlo simulation of the ATLAS SUSY analysis suite. The flexibility of this framework allows us to study a wide variety of SUSY phenomena simultaneously and to probe for weak spots in existing SU…
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We study SUSY signatures at the 7, 8 and 14 TeV LHC employing the 19-parameter, R-Parity conserving p(henomenological)MSSM, in the scenario with a neutralino LSP. Our results were obtained via a fast Monte Carlo simulation of the ATLAS SUSY analysis suite. The flexibility of this framework allows us to study a wide variety of SUSY phenomena simultaneously and to probe for weak spots in existing SUSY search analyses. We determine the ranges of the sparticle masses that are either disfavored or allowed after the searches with the 7 and 8 TeV data sets are combined. We find that natural SUSY models with light squarks and gluinos remain viable. We extrapolate to 14 TeV with both 300 fb$^{-1}$ and 3 ab$^{-1}$ of integrated luminosity and determine the expected sensitivity of the jets + MET and stop searches to the pMSSM parameter space. We find that the high-luminosity LHC will be powerful in probing SUSY with neutralino LSPs and can provide a more definitive statement on the existence of natural Supersymmetry.
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Submitted 23 October, 2014; v1 submitted 15 July, 2014;
originally announced July 2014.
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Complementarity of Dark Matter Searches in the pMSSM
Authors:
Matthew Cahill-Rowley,
Randy Cotta,
Alex Drlica-Wagner,
Stefan Funk,
JoAnne Hewett,
Ahmed Ismail,
Tom Rizzo,
Matthew Wood
Abstract:
As is well known, the search for and eventual identification of dark matter in supersymmetry requires a simultaneous, multi-pronged approach with important roles played by the LHC as well as both direct and indirect dark matter detection experiments. We examine the capabilities of these approaches in the 19-parameter p(henomenological)MSSM which provides a general framework for complementarity stu…
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As is well known, the search for and eventual identification of dark matter in supersymmetry requires a simultaneous, multi-pronged approach with important roles played by the LHC as well as both direct and indirect dark matter detection experiments. We examine the capabilities of these approaches in the 19-parameter p(henomenological)MSSM which provides a general framework for complementarity studies of neutralino dark matter. We summarize the sensitivity of dark matter searches at the 7, 8 (and eventually 14) TeV LHC, combined with those by \Fermi, CTA, IceCube/DeepCore, COUPP, LZ and XENON. The strengths and weaknesses of each of these techniques are examined and contrasted and their interdependent roles in covering the model parameter space are discussed in detail. We find that these approaches explore orthogonal territory and that advances in each are necessary to cover the Supersymmetric WIMP parameter space. We also find that different experiments have widely varying sensitivities to the various dark matter annihilation mechanisms, some of which would be completely excluded by null results from these experiments.
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Submitted 26 May, 2014;
originally announced May 2014.
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Planning the Future of U.S. Particle Physics (Snowmass 2013): Chapter 2: Intensity Frontier
Authors:
J. L. Hewett,
H. Weerts,
K. S. Babu,
J. Butler,
B. Casey,
A. de Gouvea,
R. Essig,
Y. Grossman,
D. Hitlin,
J. Jaros,
E. Kearns,
K. Kumar,
Z. Ligeti,
Z. -T. Lu,
K. Pitts,
M. Ramsey-Musolf,
J. Ritchie,
K. Scholberg,
W. Wester,
G. P. Zeller
Abstract:
These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 2, on the Intensity Frontier, discusses the program of research with high-intensity beams and rare processes. This area includes experiments on neutrinos, proton decay, charged-lepton and quark weak interact…
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These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 2, on the Intensity Frontier, discusses the program of research with high-intensity beams and rare processes. This area includes experiments on neutrinos, proton decay, charged-lepton and quark weak interactions, atomic and nuclear probes of fundamental symmetries, and searches for new, light, weakly-interacting particles.
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Submitted 23 January, 2014;
originally announced January 2014.
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Planning the Future of U.S. Particle Physics (Snowmass 2013): Chapter 1: Summary
Authors:
J. L. Rosner,
M. Bardeen,
W. Barletta,
L. A. T. Bauerdick,
R. H. Bernstein,
R. Brock,
D. Cronin-Hennessy,
M. Demarteau,
M. Dine,
J. L. Feng,
M. Gilchriese,
S. Gottlieb,
N. Graf,
N. Hadley,
J. L. Hewett,
R. Lipton,
P. McBride,
H. Nicholson,
M. E. Peskin,
P. Ramond,
S. Ritz,
I. Shipsey,
N. Varelas,
H. Weerts,
K. Yurkewicz
Abstract:
These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 1 contains the Executive Summary and the summaries of the reports of the nine working groups.
These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 1 contains the Executive Summary and the summaries of the reports of the nine working groups.
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Submitted 23 January, 2014;
originally announced January 2014.
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New Particles Working Group Report of the Snowmass 2013 Community Summer Study
Authors:
Y. Gershtein,
M. Luty,
M. Narain,
L. -T. Wang,
D. Whiteson,
K. Agashe,
L. Apanasevich,
G. Artoni,
A. Avetisyan,
H. Baer,
C. Bartels,
M. Bauer,
D. Berge,
M. Berggren,
S. Bhattacharya,
K. Black,
T. Bose,
J. Brau,
R. Brock,
E. Brownson,
M. Cahill-Rowley,
A. Cakir,
A. Chaus,
T. Cohen,
B. Coleppa
, et al. (70 additional authors not shown)
Abstract:
This report summarizes the work of the Energy Frontier New Physics working group of the 2013 Community Summer Study (Snowmass).
This report summarizes the work of the Energy Frontier New Physics working group of the 2013 Community Summer Study (Snowmass).
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Submitted 1 November, 2013;
originally announced November 2013.
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Dark Matter in the Coming Decade: Complementary Paths to Discovery and Beyond
Authors:
Sebastian Arrenberg,
Howard Baer,
Vernon Barger,
Laura Baudis,
Daniel Bauer,
James Buckley,
Matthew Cahill-Rowley,
Randel Cotta,
Alex Drlica-Wagner,
Jonathan L. Feng,
Stefan Funk,
JoAnne Hewett,
Dan Hooper,
Ahmed Ismail,
Manoj Kaplinghat,
Kyoungchul Kong,
Alexander Kusenko,
Konstantin Matchev,
Mathew McCaskey,
Daniel McKinsey,
Dan Mickelson,
Tom Rizzo,
David Sanford,
Gabe Shaughnessy,
William Shepherd
, et al. (7 additional authors not shown)
Abstract:
In this Report we discuss the four complementary searches for the identity of dark matter: direct detection experiments that look for dark matter interacting in the lab, indirect detection experiments that connect lab signals to dark matter in our own and other galaxies, collider experiments that elucidate the particle properties of dark matter, and astrophysical probes sensitive to non-gravitatio…
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In this Report we discuss the four complementary searches for the identity of dark matter: direct detection experiments that look for dark matter interacting in the lab, indirect detection experiments that connect lab signals to dark matter in our own and other galaxies, collider experiments that elucidate the particle properties of dark matter, and astrophysical probes sensitive to non-gravitational interactions of dark matter. The complementarity among the different dark matter searches is discussed qualitatively and illustrated quantitatively in several theoretical scenarios. Our primary conclusion is that the diversity of possible dark matter candidates requires a balanced program based on all four of those approaches.
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Submitted 31 October, 2013;
originally announced October 2013.
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Higgs Working Group Report of the Snowmass 2013 Community Planning Study
Authors:
S. Dawson,
A. Gritsan,
H. Logan,
J. Qian,
C. Tully,
R. Van Kooten,
A. Ajaib,
A. Anastassov,
I. Anderson,
D. Asner,
O. Bake,
V. Barger,
T. Barklow,
B. Batell,
M. Battaglia,
S. Berge,
A. Blondel,
S. Bolognesi,
J. Brau,
E. Brownson,
M. Cahill-Rowley,
C. Calancha-Paredes,
C. -Y. Chen,
W. Chou,
R. Clare
, et al. (109 additional authors not shown)
Abstract:
This report summarizes the work of the Energy Frontier Higgs Boson working group of the 2013 Community Summer Study (Snowmass). We identify the key elements of a precision Higgs physics program and document the physics potential of future experimental facilities as elucidated during the Snowmass study. We study Higgs couplings to gauge boson and fermion pairs, double Higgs production for the Higgs…
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This report summarizes the work of the Energy Frontier Higgs Boson working group of the 2013 Community Summer Study (Snowmass). We identify the key elements of a precision Higgs physics program and document the physics potential of future experimental facilities as elucidated during the Snowmass study. We study Higgs couplings to gauge boson and fermion pairs, double Higgs production for the Higgs self-coupling, its quantum numbers and $CP$-mixing in Higgs couplings, the Higgs mass and total width, and prospects for direct searches for additional Higgs bosons in extensions of the Standard Model. Our report includes projections of measurement capabilities from detailed studies of the Compact Linear Collider (CLIC), a Gamma-Gamma Collider, the International Linear Collider (ILC), the Large Hadron Collider High-Luminosity Upgrade (HL-LHC), Very Large Hadron Colliders up to 100 TeV (VLHC), a Muon Collider, and a Triple-Large Electron Positron Collider (TLEP).
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Submitted 8 January, 2014; v1 submitted 30 October, 2013;
originally announced October 2013.
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Cosmic Frontier Indirect Dark Matter Detection Working Group Summary
Authors:
J. Buckley,
D. F. Cowen,
S. Profumo,
A. Archer,
M. Cahill-Rowley,
R. Cotta,
S. Digel,
A. Drlica-Wagner,
F. Ferrer,
S. Funk,
J. Hewett,
J. Holder,
B. Humensky,
A. Ismail,
M. Israel,
T. Jeltema,
A. Olinto,
A. Peter,
J. Pretz,
T. Rizzo,
J. Siegal-Gaskins,
A. Smith,
D. Staszak,
J. Vandenbroucke,
M. Wood
Abstract:
As part of the Snowmass process, the Cosmic Frontier Indirect-Detection subgroup (CF2) has drawn on input from the Cosmic Frontier and the broader Particle Physics community to produce this document. The purposes of this report are to identify opportunities for dark matter science through indirect detection, to give an overview of the primary scientific drivers for indirect searches for dark matte…
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As part of the Snowmass process, the Cosmic Frontier Indirect-Detection subgroup (CF2) has drawn on input from the Cosmic Frontier and the broader Particle Physics community to produce this document. The purposes of this report are to identify opportunities for dark matter science through indirect detection, to give an overview of the primary scientific drivers for indirect searches for dark matter, and to survey current and planned experiments that have, as a large part of their scientific program, the goal of searching for indirect (or astrophysical) signatures of dark matter. We primarily address existing experiments with a large U.S. role, or future experiments where a U.S. contribution is sought. We also address the limitations of this technique, and answer the tough questions relevant to this subgroup posed by the HEP community through the Snowmass process.
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Submitted 25 October, 2013;
originally announced October 2013.
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Neutrinos
Authors:
A. de Gouvea,
K. Pitts,
K. Scholberg,
G. P. Zeller,
J. Alonso,
A. Bernstein,
M. Bishai,
S. Elliott,
K. Heeger,
K. Hoffman,
P. Huber,
L. J. Kaufman,
B. Kayser,
J. Link,
C. Lunardini,
B. Monreal,
J. G. Morfin,
H. Robertson,
R. Tayloe,
N. Tolich,
K. Abazajian,
T. Akiri,
C. Albright,
J. Asaadi,
K. S Babu
, et al. (142 additional authors not shown)
Abstract:
This document represents the response of the Intensity Frontier Neutrino Working Group to the Snowmass charge. We summarize the current status of neutrino physics and identify many exciting future opportunities for studying the properties of neutrinos and for addressing important physics and astrophysics questions with neutrinos.
This document represents the response of the Intensity Frontier Neutrino Working Group to the Snowmass charge. We summarize the current status of neutrino physics and identify many exciting future opportunities for studying the properties of neutrinos and for addressing important physics and astrophysics questions with neutrinos.
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Submitted 16 October, 2013;
originally announced October 2013.
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The CP-violating pMSSM at the Intensity Frontier
Authors:
Joshua Berger,
Matthew W. Cahill-Rowley,
Diptimoy Ghosh,
JoAnne L. Hewett,
Ahmed Ismail,
Thomas G. Rizzo
Abstract:
In this Snowmass whitepaper, we describe the impact of ongoing and proposed intensity frontier experiments on the parameter space of the Minimally Supersymmetric Standard Model (MSSM). We extend a set of phenomenological MSSM (pMSSM) models to include non-zero CP-violating phases and study the sensitivity of various flavor observables in these scenarios Future electric dipole moment and rare meson…
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In this Snowmass whitepaper, we describe the impact of ongoing and proposed intensity frontier experiments on the parameter space of the Minimally Supersymmetric Standard Model (MSSM). We extend a set of phenomenological MSSM (pMSSM) models to include non-zero CP-violating phases and study the sensitivity of various flavor observables in these scenarios Future electric dipole moment and rare meson decay experiments can have a strong impact on the viability of these models that is relatively independent of the detailed superpartner spectrum. In particular, we find that these experiments have the potential to probe models that are expected to escape searches at the high-luminosity LHC.
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Submitted 29 September, 2013;
originally announced September 2013.
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Constraints on Higgs Properties and SUSY Partners in the pMSSM
Authors:
Matthew Cahill-Rowley,
JoAnne Hewett,
Ahmed Ismail,
Tom Rizzo
Abstract:
Direct searches for superpartners and precision measurements of the properties of the $\sim 126$ GeV Higgs boson lead to important inter-dependent constraints on the underlying parameter space of the MSSM. The 19/20-parameter p(henomenological)MSSM offers a flexible framework for the study of a wide variety of both Higgs and SUSY phenomena at the LHC and elsewhere. Within this scenario we address…
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Direct searches for superpartners and precision measurements of the properties of the $\sim 126$ GeV Higgs boson lead to important inter-dependent constraints on the underlying parameter space of the MSSM. The 19/20-parameter p(henomenological)MSSM offers a flexible framework for the study of a wide variety of both Higgs and SUSY phenomena at the LHC and elsewhere. Within this scenario we address the following questions: `What will potentially null searches for SUSY at the LHC tell us about the possible properties of the Higgs boson?' and, conversely, `What do precision measurements of the properties of the Higgs tell us about the possible properties of the various superpartners?' Clearly the answers to such questions will be functions of both the collision energy of the LHC as well as the accumulated integrated luminosity. We address these questions employing several sets of pMSSM models having either neutralino or gravitino LSPs, making use of the ATLAS SUSY analyses at the 7/8 TeV LHC as well as planned SUSY and Higgs analyses at the 14 TeV LHC and the ILC. Except for theoretical uncertainties that remain to be accounted for in the ratios of SUSY and SM couplings, we demonstrate that Higgs coupling measurements at the 14 TeV LHC, and particularly at the 500 GeV ILC, will be sensitive to regions of the pMSSM model space that are not accessible to direct SUSY searches.
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Submitted 30 September, 2013; v1 submitted 1 August, 2013;
originally announced August 2013.
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pMSSM Studies at the 7, 8 and 14 TeV LHC
Authors:
M. Cahill-Rowley,
J. L. Hewett,
A. Ismail,
T. G. Rizzo
Abstract:
The 19/20-parameter p(henomenological)MSSM with either a neutralino or gravitino LSP offers a flexible framework for the study of a wide variety of R-parity conserving MSSM SUSY phenomena at the 7, 8 and 14 TeV LHC. Here we present the results of a study of SUSY signatures at these facilities obtained via a fast Monte Carlo 'replication' of the ATLAS SUSY analysis suite. In particular, we show the…
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The 19/20-parameter p(henomenological)MSSM with either a neutralino or gravitino LSP offers a flexible framework for the study of a wide variety of R-parity conserving MSSM SUSY phenomena at the 7, 8 and 14 TeV LHC. Here we present the results of a study of SUSY signatures at these facilities obtained via a fast Monte Carlo 'replication' of the ATLAS SUSY analysis suite. In particular, we show the ranges of the sparticle masses that are either disfavored or remain viable after all of the various searches at the 7 and 8 TeV runs are combined. We then extrapolate to 14 TeV with both 300 fb^-1 and 3 ab^-1 of integrated luminosity and determine the sensitivity of a jets + MET search to the pMSSM parameter space. We find that the high-luminosity LHC performs extremely well in probing natural SUSY models.
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Submitted 30 September, 2013; v1 submitted 31 July, 2013;
originally announced July 2013.
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Complementarity and Searches for Dark Matter in the pMSSM
Authors:
M. Cahill-Rowley,
R. Cotta,
A. Drlica-Wagner,
S. Funk,
J. Hewett,
A. Ismail,
T. Rizzo,
M. Wood
Abstract:
The search for and identification of neutralino dark matter in supersymmetry requires a multi-pronged approach with important roles played by collider, direct and indirect dark matter detection experiments. In this report, we summarize the sensitivity of such searches at the 7, 8 (and eventually 14) TeV LHC, combined with those by Fermi, CTA, IceCube/DeepCore, COUPP and XENON1T, to such particles…
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The search for and identification of neutralino dark matter in supersymmetry requires a multi-pronged approach with important roles played by collider, direct and indirect dark matter detection experiments. In this report, we summarize the sensitivity of such searches at the 7, 8 (and eventually 14) TeV LHC, combined with those by Fermi, CTA, IceCube/DeepCore, COUPP and XENON1T, to such particles within the context of the 19-parameter p(henomenological)MSSM. This report provides an outline of the current status of our results and our expectations for future analyses.
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Submitted 30 September, 2013; v1 submitted 29 May, 2013;
originally announced May 2013.
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Up Sector of Minimal Flavor Violation: Top Quark Properties and Direct D meson CP violation
Authors:
Yang Bai,
Joshua Berger,
JoAnne L. Hewett,
Ye Li
Abstract:
Minimal Flavor Violation in the up-type quark sector leads to particularly interesting phenomenology due to the interplay of flavor physics in the charm sector and collider physics from flavor changing processes in the top sector. We study the most general operators that can affect top quark properties and $D$ meson decays in this scenario, concentrating on two CP violating operators for detailed…
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Minimal Flavor Violation in the up-type quark sector leads to particularly interesting phenomenology due to the interplay of flavor physics in the charm sector and collider physics from flavor changing processes in the top sector. We study the most general operators that can affect top quark properties and $D$ meson decays in this scenario, concentrating on two CP violating operators for detailed studies. The consequences of these effective operators on charm and top flavor changing processes are generically small, but can be enhanced if there exists a light flavor mediator that is a Standard Model gauge singlet scalar and transforms under the flavor symmetry group. This flavor mediator can satisfy the current experimental bounds with a mass as low as tens of GeV and explain observed $D$-meson direct CP violation. Additionally, the model predicts a non-trivial branching fraction for a top quark decay that would mimic a dijet resonance.
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Submitted 23 May, 2013;
originally announced May 2013.
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pMSSM Benchmark Models for Snowmass 2013
Authors:
Matthew W. Cahill-Rowley,
JoAnne L. Hewett,
Ahmed Ismail,
Michael E. Peskin,
Thomas G. Rizzo
Abstract:
We present several benchmark points in the phenomenological Minimal Supersymmetric Standard Model (pMSSM). We select these models as experimentally well-motivated examples of the MSSM which predict the observed Higgs mass and dark matter relic density while evading the current LHC searches. We also use benchmarks to generate spokes in parameter space by scaling the mass parameters in a manner whic…
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We present several benchmark points in the phenomenological Minimal Supersymmetric Standard Model (pMSSM). We select these models as experimentally well-motivated examples of the MSSM which predict the observed Higgs mass and dark matter relic density while evading the current LHC searches. We also use benchmarks to generate spokes in parameter space by scaling the mass parameters in a manner which keeps the Higgs mass and relic density approximately constant.
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Submitted 10 May, 2013;
originally announced May 2013.
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Dark Matter in the Coming Decade: Complementary Paths to Discovery and Beyond
Authors:
Daniel Bauer,
James Buckley,
Matthew Cahill-Rowley,
Randel Cotta,
Alex Drlica-Wagner,
Jonathan L. Feng,
Stefan Funk,
JoAnne Hewett,
Dan Hooper,
Ahmed Ismail,
Manoj Kaplinghat,
Alexander Kusenko,
Konstantin Matchev,
Daniel McKinsey,
Tom Rizzo,
William Shepherd,
Tim M. P. Tait,
Alexander M. Wijangco,
Matthew Wood
Abstract:
In this report we summarize the many dark matter searches currently being pursued through four complementary approaches: direct detection, indirect detection, collider experiments, and astrophysical probes. The essential features of broad classes of experiments are described, each with their own strengths and weaknesses. The complementarity of the different dark matter searches is discussed qualit…
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In this report we summarize the many dark matter searches currently being pursued through four complementary approaches: direct detection, indirect detection, collider experiments, and astrophysical probes. The essential features of broad classes of experiments are described, each with their own strengths and weaknesses. The complementarity of the different dark matter searches is discussed qualitatively and illustrated quantitatively in two simple theoretical frameworks. Our primary conclusion is that the diversity of possible dark matter candidates requires a balanced program drawing from all four approaches.
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Submitted 3 July, 2015; v1 submitted 7 May, 2013;
originally announced May 2013.
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SUSY Without Prejudice at the 7 and 8 TeV LHC: Gravitino LSPs
Authors:
M. W. Cahill-Rowley,
J. L. Hewett,
A. Ismail,
T. G. Rizzo
Abstract:
We have examined the capability of the LHC, running at both 7 and 8 TeV, to explore the 19(20)-dimensional parameter space of the pMSSM with neutralino(gravitino) LSPs and soft masses up to 4 TeV employing the ATLAS SUSY analysis suite. Here we present some preliminary results for the gravitino model set, following the ATLAS analyses whose data were publically available as of mid-September 2012. W…
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We have examined the capability of the LHC, running at both 7 and 8 TeV, to explore the 19(20)-dimensional parameter space of the pMSSM with neutralino(gravitino) LSPs and soft masses up to 4 TeV employing the ATLAS SUSY analysis suite. Here we present some preliminary results for the gravitino model set, following the ATLAS analyses whose data were publically available as of mid-September 2012. We find that the impact of the reduced MET, resulting from models with gravitino LSPs on sparticle searches is more than off-set by the detectability of the many possible long-lived NLSPs.
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Submitted 29 November, 2012;
originally announced November 2012.
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More Energy, More Searches, but the pMSSM Lives On
Authors:
Matthew W. Cahill-Rowley,
JoAnne L. Hewett,
Ahmed Ismail,
Thomas G. Rizzo
Abstract:
We further examine the capability of the 7 and 8 TeV LHC to explore the parameter space of the p(henomenological)MSSM with neutralino LSPs. Here we present an updated study employing all of the relevant ATLAS SUSY analyses, as well as all relevant LHC non-MET searches, whose data were publically available as of mid-September 2012. We find that roughly 1/3 of our pMSSM model points are excluded at…
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We further examine the capability of the 7 and 8 TeV LHC to explore the parameter space of the p(henomenological)MSSM with neutralino LSPs. Here we present an updated study employing all of the relevant ATLAS SUSY analyses, as well as all relevant LHC non-MET searches, whose data were publically available as of mid-September 2012. We find that roughly 1/3 of our pMSSM model points are excluded at present with an important role being played by both the heavy flavor and multi-lepton searches, as well as those for heavy stable charged particles. Nonetheless, we find that light gluinos, 1st/2nd generation squarks, and stop/sbottoms (\lsim 400-700 GeV), as well as models with 1% fine-tuning or better, are still viable in the pMSSM. In addition, we see that increased luminosity at 8 TeV is unlikely to significantly improve the reach of the "vanilla" searches. The impact of these null searches on the SUSY sparticle spectrum is discussed in detail and the implications of these results for models with low fine-tuning, a future lepton collider and dark matter searches are examined.
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Submitted 26 March, 2013; v1 submitted 8 November, 2012;
originally announced November 2012.
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Bounds on Dark Matter Interactions with Electroweak Gauge Bosons
Authors:
R. C. Cotta,
J. L. Hewett,
M. P. Le,
T. G. Rizzo
Abstract:
We investigate scenarios in which dark matter interacts with the Standard Model primarily through electroweak gauge bosons. We employ an effective field theory framework wherein the Standard Model and the dark matter particle are the only light states in order to derive model-independent bounds. Bounds on such interactions are derived from dark matter production by weak boson fusion at the LHC, in…
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We investigate scenarios in which dark matter interacts with the Standard Model primarily through electroweak gauge bosons. We employ an effective field theory framework wherein the Standard Model and the dark matter particle are the only light states in order to derive model-independent bounds. Bounds on such interactions are derived from dark matter production by weak boson fusion at the LHC, indirect detection searches for the products of dark matter annihilation and from the measured invisible width of the $Z^0$. We find that limits on the UV scale, $Λ$, reach weak scale values for most operators and values of the dark matter mass, thus probing the most natural scenarios in the WIMP dark matter paradigm. Our bounds suggest that light dark matter ($m_χ\lsim m_Z/2$ or $m_χ\lsim 100-200\gev$, depending on the operator) cannot interact only with the electroweak gauge bosons of the Standard Model, but rather requires additional operator contributions or dark sector structure to avoid overclosing the universe.
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Submitted 1 October, 2012;
originally announced October 2012.
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The Higgs Sector and Fine-Tuning in the pMSSM
Authors:
Matthew W. Cahill-Rowley,
JoAnne L. Hewett,
Ahmed Ismail,
Thomas G. Rizzo
Abstract:
The recent discovery of a 125 GeV Higgs, as well as the lack of any positive findings in searches for supersymmetry, has renewed interest in both the supersymmetric Higgs sector and fine-tuning. Here, we continue our study of the phenomenological MSSM (pMSSM), discussing the light Higgs and fine-tuning within the context of two sets of previously generated pMSSM models. We find an abundance of mod…
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The recent discovery of a 125 GeV Higgs, as well as the lack of any positive findings in searches for supersymmetry, has renewed interest in both the supersymmetric Higgs sector and fine-tuning. Here, we continue our study of the phenomenological MSSM (pMSSM), discussing the light Higgs and fine-tuning within the context of two sets of previously generated pMSSM models. We find an abundance of models with experimentally-favored Higgs masses and couplings. We investigate the decay modes of the light Higgs in these models, finding strong correlations between many final states. We then examine the degree of fine-tuning, considering contributions from each of the pMSSM parameters at up to next-to-leading-log order. In particular, we examine the fine-tuning implications for our model sets that arise from the discovery of a 125 GeV Higgs. Finally, we investigate a small subset of models with low fine-tuning and a light Higgs near 125 GeV, describing the common features of such models. We generically find a light stop and bottom with complex decay patterns into a set of light electroweak gauginos, which will make their discovery more challenging and may require novel search techniques.
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Submitted 7 July, 2012; v1 submitted 25 June, 2012;
originally announced June 2012.
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The New Look pMSSM with Neutralino and Gravitino LSPs
Authors:
Matthew W. Cahill-Rowley,
JoAnne L. Hewett,
Stefan Hoeche,
Ahmed Ismail,
Thomas G. Rizzo
Abstract:
The pMSSM provides a broad perspective on SUSY phenomenology. In this paper we generate two new, very large, sets of pMSSM models with sparticle masses extending up to 4 TeV, where the lightest supersymmetric particle (LSP) is either a neutralino or gravitino. The existence of a gravitino LSP necessitates a detailed study of its cosmological effects and we find that Big Bang Nucleosynthesis places…
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The pMSSM provides a broad perspective on SUSY phenomenology. In this paper we generate two new, very large, sets of pMSSM models with sparticle masses extending up to 4 TeV, where the lightest supersymmetric particle (LSP) is either a neutralino or gravitino. The existence of a gravitino LSP necessitates a detailed study of its cosmological effects and we find that Big Bang Nucleosynthesis places strong constraints on this scenario. Both sets are subjected to a global set of theoretical, observational and experimental constraints resulting in a sample of \sim 225k viable models for each LSP type. The characteristics of these two model sets are briefly compared. We confront the neutralino LSP model set with searches for SUSY at the 7 TeV LHC using both the missing (MET) and non-missing ET ATLAS analyses. In the MET case, we employ Monte Carlo estimates of the ratios of the SM backgrounds at 7 and 8 TeV to rescale the 7 TeV data-driven ATLAS backgrounds to 8 TeV. This allows us to determine the pMSSM parameter space coverage for this collision energy. We find that an integrated luminosity of \sim 5-20 fb^{-1} at 8 TeV would yield a substantial increase in this coverage compared to that at 7 TeV and can probe roughly half of the model set. If the pMSSM is not discovered during the 8 TeV run, then our model set will be essentially void of gluinos and lightest first and second generation squarks that are \lesssim 700-800 GeV, which is much less than the analogous mSUGRA bound. Finally, we demonstrate that non-MET SUSY searches continue to play an important role in exploring the pMSSM parameter space. These two pMSSM model sets can be used as the basis for investigations for years to come.
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Submitted 30 June, 2012; v1 submitted 19 June, 2012;
originally announced June 2012.
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Fundamental Physics at the Intensity Frontier
Authors:
J. L. Hewett,
H. Weerts,
R. Brock,
J. N. Butler,
B. C. K. Casey,
J. Collar,
A. de Gouvea,
R. Essig,
Y. Grossman,
W. Haxton,
J. A. Jaros,
C. K. Jung,
Z. T. Lu,
K. Pitts,
Z. Ligeti,
J. R. Patterson,
M. Ramsey-Musolf,
J. L. Ritchie,
A. Roodman,
K. Scholberg,
C. E. M. Wagner,
G. P. Zeller,
S. Aefsky,
A. Afanasev,
K. Agashe
, et al. (443 additional authors not shown)
Abstract:
The Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. Science opportunities at the intensity frontier are identified and described in the areas of heavy quarks, charged leptons, neutrinos, proton decay, new light weakly-coupled particles, and nucleons, nuclei, and atoms.
The Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. Science opportunities at the intensity frontier are identified and described in the areas of heavy quarks, charged leptons, neutrinos, proton decay, new light weakly-coupled particles, and nucleons, nuclei, and atoms.
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Submitted 11 May, 2012;
originally announced May 2012.
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Searches for New Physics: Les Houches Recommendations for the Presentation of LHC Results
Authors:
S. Kraml,
B. C. Allanach,
M. Mangano,
H. B. Prosper,
S. Sekmen,
C. Balazs,
A. Barr,
P. Bechtle,
G. Belanger,
A. Belyaev,
K. Benslama,
M. Campanelli,
K. Cranmer,
A. De Roeck,
M. J. Dolan,
T. Eifert,
J. R. Ellis,
M. Felcini,
B. Fuks,
D. Guadagnoli,
J. F. Gunion,
S. Heinemeyer,
J. Hewett,
A. Ismail,
M. Kadastik
, et al. (8 additional authors not shown)
Abstract:
We present a set of recommendations for the presentation of LHC results on searches for new physics, which are aimed at providing a more efficient flow of scientific information between the experimental collaborations and the rest of the high energy physics community, and at facilitating the interpretation of the results in a wide class of models. Implementing these recommendations would aid the f…
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We present a set of recommendations for the presentation of LHC results on searches for new physics, which are aimed at providing a more efficient flow of scientific information between the experimental collaborations and the rest of the high energy physics community, and at facilitating the interpretation of the results in a wide class of models. Implementing these recommendations would aid the full exploitation of the physics potential of the LHC.
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Submitted 20 March, 2012; v1 submitted 12 March, 2012;
originally announced March 2012.
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Les Houches 2011: Physics at TeV Colliders New Physics Working Group Report
Authors:
G. Brooijmans,
B. Gripaios,
F. Moortgat,
J. Santiago,
P. Skands,
D. Albornoz Vásquez,
B. C. Allanach,
A. Alloul,
A. Arbey,
A. Azatov,
H. Baer,
C. Balázs,
A. Barr,
L. Basso,
M. Battaglia,
P. Bechtle,
G. Bélanger,
A. Belyaev,
K. Benslama,
L. Bergström,
A. Bharucha,
C. Boehm,
M. Bondarenko,
O. Bondu,
E. Boos
, et al. (119 additional authors not shown)
Abstract:
We present the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 30 May-17 June, 2011). Our report includes new agreements on formats for interfaces between computational tools, new tool developments, important signatures for searches at the LHC, recommendations for presentation of LHC search results, as well as additional phenomenologi…
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We present the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 30 May-17 June, 2011). Our report includes new agreements on formats for interfaces between computational tools, new tool developments, important signatures for searches at the LHC, recommendations for presentation of LHC search results, as well as additional phenomenological studies.
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Submitted 20 April, 2012; v1 submitted 7 March, 2012;
originally announced March 2012.
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Hiding a Heavy Higgs Boson at the 7 TeV LHC
Authors:
Yang Bai,
JiJi Fan,
JoAnne L. Hewett
Abstract:
A heavy Standard Model Higgs boson is not only disfavored by electroweak precision observables but is also excluded by direct searches at the 7 TeV LHC for a wide range of masses. Here, we examine scenarios where a heavy Higgs boson can be made consistent with both the indirect constraints and the direct null searches by adding only one new particle beyond the Standard Model. This new particle sho…
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A heavy Standard Model Higgs boson is not only disfavored by electroweak precision observables but is also excluded by direct searches at the 7 TeV LHC for a wide range of masses. Here, we examine scenarios where a heavy Higgs boson can be made consistent with both the indirect constraints and the direct null searches by adding only one new particle beyond the Standard Model. This new particle should be a weak multiplet in order to have additional contributions to the oblique parameters. If it is a color singlet, we find that a heavy Higgs with an intermediate mass of 200 - 300 GeV can decay into the new states, suppressing the branching ratios for the standard model modes, and thus hiding a heavy Higgs at the LHC. If the new particle is also charged under QCD, the Higgs production cross section from gluon fusion can be reduced significantly due to the new colored particle one-loop contribution. Current collider constraints on the new particles allow for viable parameter space to exist in order to hide a heavy Higgs boson. We categorize the general signatures of these new particles, identify favored regions of their parameter space and point out that discovering or excluding them at the LHC can provide important indirect information for a heavy Higgs. Finally, for a very heavy Higgs boson, beyond the search limit at the 7 TeV LHC, we discuss three additional scenarios where models would be consistent with electroweak precision tests: including an additional vector-like fermion mixing with the top quark, adding another U(1) gauge boson and modifying triple-gauge boson couplings.
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Submitted 8 December, 2011;
originally announced December 2011.
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Constraints on the pMSSM from LAT Observations of Dwarf Spheroidal Galaxies
Authors:
R. C. Cotta,
A. Drlica-Wagner,
S. Murgia,
E. D. Bloom,
J. L. Hewett,
T. G. Rizzo
Abstract:
We examine the ability for the Large Area Telescope (LAT) to constrain Minimal Supersymmetric Standard Model (MSSM) dark matter through a combined analysis of Milky Way dwarf spheroidal galaxies. We examine the Lightest Supersymmetric Particles (LSPs) for a set of ~71k experimentally valid supersymmetric models derived from the phenomenological-MSSM (pMSSM). We find that none of these models can b…
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We examine the ability for the Large Area Telescope (LAT) to constrain Minimal Supersymmetric Standard Model (MSSM) dark matter through a combined analysis of Milky Way dwarf spheroidal galaxies. We examine the Lightest Supersymmetric Particles (LSPs) for a set of ~71k experimentally valid supersymmetric models derived from the phenomenological-MSSM (pMSSM). We find that none of these models can be excluded at 95% confidence by the current analysis; nevertheless, many lie within the predicted reach of future LAT analyses. With two years of data, we find that the LAT is currently most sensitive to light LSPs (m_LSP < 50 GeV) annihilating into tau-pairs and heavier LSPs annihilating into b-bbar. Additionally, we find that future LAT analyses will be able to probe some LSPs that form a sub-dominant component of dark matter. We directly compare the LAT results to direct detection experiments and show the complementarity of these search methods.
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Submitted 10 November, 2011;
originally announced November 2011.
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Zeroing in on Supersymmetric Radiation Amplitude Zeros
Authors:
JoAnne L. Hewett,
Ahmed Ismail,
Thomas G. Rizzo
Abstract:
Radiation amplitude zeros have long been used to test the Standard Model. Here, we consider the supersymmetric radiation amplitude zero in chargino-neutralino associated production, which can be observed at the luminosity upgraded LHC. Such an amplitude zero only occurs if the neutralino has a large wino fraction and hence this observable can be used to determine the neutralino eigenstate content.…
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Radiation amplitude zeros have long been used to test the Standard Model. Here, we consider the supersymmetric radiation amplitude zero in chargino-neutralino associated production, which can be observed at the luminosity upgraded LHC. Such an amplitude zero only occurs if the neutralino has a large wino fraction and hence this observable can be used to determine the neutralino eigenstate content. We find that this observable can be measured by comparing the p_T spectrum of the softest lepton in the trilepton $χ_1^\pm χ_2^0$ decay channel to that of a control process such as $χ_1^+ χ_1^-$ or $χ_2^0 χ_2^0$. We test this technique on a previously generated model sample of the 19 dimensional parameter space of the phenomenological MSSM, and find that it is effective in determining the wino content of the neutralino.
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Submitted 18 October, 2011;
originally announced October 2011.
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Dissecting the Wjj Anomaly: Diagnostic Tests of a Leptophobic Z'
Authors:
J. L. Hewett,
T. G. Rizzo
Abstract:
We examine the scenario where a leptophobic Z' boson accounts for the excess of events in the Wjj channel as observed by CDF. We assume generation independent couplings for the Z' and obtain allowed regions for the four hadronic couplings using the cross section range quoted by CDF as well as constraints from dijet production at UA2. These coupling regions translate into well-determined rates for…
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We examine the scenario where a leptophobic Z' boson accounts for the excess of events in the Wjj channel as observed by CDF. We assume generation independent couplings for the Z' and obtain allowed regions for the four hadronic couplings using the cross section range quoted by CDF as well as constraints from dijet production at UA2. These coupling regions translate into well-determined rates for the associated production of Z/γ+Z' at the Tevatron and LHC, as well as W+Z' at the LHC,that are directly correlated with the Wjj rate observed at the Tevatron. The Wjj rate at the LHC is large and this channel should be observed soon once the SM backgrounds are under control. The rates for Z/γ+Z' associated production are smaller, and these processes should not yet have been observed at the Tevatron given the expected SM backgrounds. In addition, we also show that valuable coupling information is obtainable from the distributions of other kinematic variables, e.g., M_{WZ'}, p_T^W, and \cos θ_W^*. Once detected, these associated production processes and the corresponding kinematic distributions examined here will provide further valuable information on the Z' boson couplings.
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Submitted 12 August, 2011; v1 submitted 1 June, 2011;
originally announced June 2011.
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Simplified Models for LHC New Physics Searches
Authors:
Daniele Alves,
Nima Arkani-Hamed,
Sanjay Arora,
Yang Bai,
Matthew Baumgart,
Joshua Berger,
Matthew Buckley,
Bart Butler,
Spencer Chang,
Hsin-Chia Cheng,
Clifford Cheung,
R. Sekhar Chivukula,
Won Sang Cho,
Randy Cotta,
Mariarosaria D'Alfonso,
Sonia El Hedri,
Rouven Essig,
Jared A. Evans,
Liam Fitzpatrick,
Patrick Fox,
Roberto Franceschini,
Ayres Freitas,
James S. Gainer,
Yuri Gershtein,
Richard Gray
, et al. (70 additional authors not shown)
Abstract:
This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified m…
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This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the "Topologies for Early LHC Searches" workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first ~50-500 pb-1 of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.
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Submitted 13 May, 2011;
originally announced May 2011.
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pMSSM Dark Matter Searches on Ice
Authors:
R. C. Cotta,
K. T. K. Howe,
J. L. Hewett,
T. G. Rizzo
Abstract:
We explore the capability of the IceCube/Deepcore array to discover signal neutrinos resulting from the annihilations of Supersymmetric WIMPS that may be captured in the solar core. In this analysis, we use a previously generated set of /sim 70k model points in the 19-dimensional parameter space of the pMSSM which satisfy existing experimental and theoretical constraints. Our calculations employ a…
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We explore the capability of the IceCube/Deepcore array to discover signal neutrinos resulting from the annihilations of Supersymmetric WIMPS that may be captured in the solar core. In this analysis, we use a previously generated set of /sim 70k model points in the 19-dimensional parameter space of the pMSSM which satisfy existing experimental and theoretical constraints. Our calculations employ a realistic estimate of the IceCube/DeepCore effective area that has been modeled by the IceCube collaboration. We find that a large fraction of the pMSSM models are shown to have significant signal rates in the anticipated IceCube/DeepCore 1825 day dataset, including some prospects for an early discovery. Many models where the LSP only constitutes a small fraction of the total dark matter relic density are found to have observable rates. We investigate in detail the dependence of the signal neutrino fluxes on the LSP mass, weak eigenstate composition, annihilation products and thermal relic density, as well as on the spin-independent and spin-dependent scattering cross sections. Lastly, We compare the model coverage of IceCube/DeepCore to that obtainable in near-future direct detection experiments and to pMSSM searches at the 7 TeV LHC.
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Submitted 5 May, 2011;
originally announced May 2011.
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Higgs Properties in the Fourth Generation MSSM: Boosted Signals Over the 3G Plan
Authors:
R. C. Cotta,
J. L. Hewett,
A. Ismail,
M. -P. Le,
T. G. Rizzo
Abstract:
The generalization of the MSSM to the case of four chiral fermion generations (4GMSSM) can lead to significant changes in the phenomenology of the otherwise familiar Higgs sector. In most of the 3GMSSM parameter space, the lighter CP-even $h$ is $\sim 115-125$ GeV and mostly Standard Model-like while $H,A,H^\pm$ are all relatively heavy. Furthermore, the ratio of Higgs vevs, $\tan β$, is relativel…
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The generalization of the MSSM to the case of four chiral fermion generations (4GMSSM) can lead to significant changes in the phenomenology of the otherwise familiar Higgs sector. In most of the 3GMSSM parameter space, the lighter CP-even $h$ is $\sim 115-125$ GeV and mostly Standard Model-like while $H,A,H^\pm$ are all relatively heavy. Furthermore, the ratio of Higgs vevs, $\tan β$, is relatively unconstrained. In contrast to this, in the 4GMSSM, heavy fourth generation fermion loops drive the masses of $h,H,H^\pm$ to large values while the CP-odd boson, $A$, can remain relatively light and $\tan β$ is restricted to the range $1/2 \lsim \tan β\lsim 2$ due to perturbativity requirements on Yukawa couplings. We explore this scenario in some detail, concentrating on the collider signatures of the light CP-odd Higgs at both the Tevatron and LHC. We find that while $gg \to A$ may lead to a potential signal in the $τ^+τ^-$ channel at the LHC, $A$ may first be observed in the $γγ$ channel due to a highly loop-enhanced cross section that can be more than an order of magnitude greater than that of a SM Higgs for $A$ masses of $\sim 115-120$ and $\tanβ<1$. We find that the CP-even states $h,H$ are highly mixed and can have atypical branching fractions. Precision electroweak constraints, particularly for the light $A$ parameter space region, are examined in detail.
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Submitted 6 May, 2011; v1 submitted 29 April, 2011;
originally announced May 2011.
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$A^t_{FB}$ Meets LHC
Authors:
JoAnne L. Hewett,
Jessie Shelton,
Michael Spannowsky,
Tim M. P. Tait,
Michihisa Takeuchi
Abstract:
The recent Tevatron measurement of the forward-backward asymmetry of the top quark shows an intriguing discrepancy with Standard Model expectations, particularly at large $\ttbar$ invariant masses. Measurements of this quantity are subtle at the LHC, due to its $pp$ initial state, however, one can define a forward-central-charge asymmetry which captures the physics. We study the capability of the…
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The recent Tevatron measurement of the forward-backward asymmetry of the top quark shows an intriguing discrepancy with Standard Model expectations, particularly at large $\ttbar$ invariant masses. Measurements of this quantity are subtle at the LHC, due to its $pp$ initial state, however, one can define a forward-central-charge asymmetry which captures the physics. We study the capability of the LHC to measure this asymmetry and find that within the SM a measurement at the $5σ$ level is possible with roughly 60 fb$^{-1}$ at $\sqrt{s} = 14$ TeV. If nature realizes a model which enhances the asymmetry (as is necessary to explain the Tevatron measurements), a significant difference from zero can be observed much earlier, perhaps even during early LHC running at $\sqrt{s} = 7$ TeV. We further explore the capabilities of the 7 TeV LHC to discover resonances or contact interactions which modify the $\ttbar$ invariant mass distribution using recent boosted top tagging techniques. We find that TeV-scale color octet resonances can be discovered, even with small coupling strengths and that contact interactions can be probed at scales exceeding 6 TeV. Overall, the LHC has good potential to clarify the situation with regards to the Tevatron forward-backward measurement.
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Submitted 12 April, 2011; v1 submitted 23 March, 2011;
originally announced March 2011.
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Supersymmetry Without Prejudice at the 7 TeV LHC
Authors:
John A. Conley,
James S. Gainer,
JoAnne L. Hewett,
My Phuong Le,
Thomas G. Rizzo
Abstract:
We investigate the model independent nature of the Supersymmetry search strategies at the 7 TeV LHC. To this end, we study the missing-transverse-energy-based searches developed by the ATLAS Collaboration that were essentially designed for mSUGRA. We simulate the signals for ~71k models in the 19-dimensional parameter space of the pMSSM. These models have been found to satisfy existing experimenta…
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We investigate the model independent nature of the Supersymmetry search strategies at the 7 TeV LHC. To this end, we study the missing-transverse-energy-based searches developed by the ATLAS Collaboration that were essentially designed for mSUGRA. We simulate the signals for ~71k models in the 19-dimensional parameter space of the pMSSM. These models have been found to satisfy existing experimental and theoretical constraints and provide insight into general features of the MSSM without reference to a particular SUSY breaking scenario or any other assumptions at the GUT scale. Using backgrounds generated by ATLAS, we find that imprecise knowledge of these estimated backgrounds is a limiting factor in the potential discovery of these models and that some channels become systematics-limited at larger luminosities. As this systematic error is varied between 20-100%, roughly half to 90% of this model sample is observable with significance S>5 for 1 fb^{-1} of integrated luminosity. We then examine the model characteristics for the cases which cannot be discovered and find several contributing factors. We find that a blanket statement that squarks and gluinos are excluded with masses below a specific value cannot be made. We next explore possible modifications to the kinematic cuts in these analyses that may improve the pMSSM model coverage. Lastly, we examine the implications of a null search at the 7 TeV LHC in terms of the degree of fine-tuning that would be present in this model set and for sparticle production at the 500 GeV and 1 TeV Linear Collider.
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Submitted 8 March, 2011;
originally announced March 2011.