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Strong Coupling Constant Determination from the new CTEQ-TEA Global QCD Analysis
Authors:
Alim Ablat,
Sayipjamal Dulat,
Marco Guzzi,
Joey Huston,
Kirtimaan Mohan,
Pavel Nadolsky,
Dan Stump,
C. -P. Yuan
Abstract:
We present a new determination of the strong coupling constant $α_s$ from a global QCD analysis CT25 of parton distribution functions (PDFs) that incorporates high-precision experimental measurements from the Run-2 of the Large Hadron Collider together with a large sample of other measurements over a wide interval of energies. This work addresses two objectives: providing an up-to-date determinati…
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We present a new determination of the strong coupling constant $α_s$ from a global QCD analysis CT25 of parton distribution functions (PDFs) that incorporates high-precision experimental measurements from the Run-2 of the Large Hadron Collider together with a large sample of other measurements over a wide interval of energies. This work addresses two objectives: providing an up-to-date determination of $α_s$ using NNLO calculations and a sensitive nucleon data set within a self-consistent framework, and critically assessing the robustness of the $α_s(M_Z)$ extraction in light of systematic uncertainties as well as correlations of $α_s(M_Z)$ with the functional forms of PDFs and other model parameters. In regard to the uncertainty assessment, we demonstrate that some commonly used criteria, including the dynamical tolerance and Bayesian hierarchical models, may produce significantly different or even unstable estimates for the net $α_s$ uncertainty, and we introduce a concept of \textit{data-clustering safety} that the replicable uncertainty estimates must satisfy. Based on this in-depth examination of the CT25 global hadronic data set using a combination of analysis methods, and after demonstrating a weak correlation between $α_s$ and the functional forms of CT25 PDF parametrizations, we find $α_s(M_Z)=0.1183^{+0.0023}_{-0.0020}$ at the 68\% credibility level.
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Submitted 17 March, 2026; v1 submitted 29 December, 2025;
originally announced December 2025.
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CT25: Progress toward next-generation PDFs for precision phenomenology at the LHC
Authors:
A. Ablat,
A. Courtoy,
S. Dulat,
Y. Fu,
M. Guzzi,
T. J. Hobbs,
J. Huston,
K. Mohan,
P. Nadolsky,
M. Ponce-Chavez,
D. Stump,
K. Xie,
C. -P. Yuan
Abstract:
We summarize recent progress toward the next generation of CTEQ-TEA parton distribution functions, CT25, based on a global NNLO analysis that incorporates a significant sample of newly included LHC data. We present a baseline fit within the forthcoming full CT25 fit, which includes new Drell-Yan, top-pair, and inclusive-jet data at 8 and 13 TeV, and exhibits non-trivial pulls on the high-$x$ gluon…
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We summarize recent progress toward the next generation of CTEQ-TEA parton distribution functions, CT25, based on a global NNLO analysis that incorporates a significant sample of newly included LHC data. We present a baseline fit within the forthcoming full CT25 fit, which includes new Drell-Yan, top-pair, and inclusive-jet data at 8 and 13 TeV, and exhibits non-trivial pulls on the high-$x$ gluon and the flavor structure of the quark sea. In the context of progress toward CT25, we also summarize several recent and ongoing studies of the interplay between phenomenological PDFs and lattice-QCD calculations, simultaneous extractions of $α_s(M_Z)$ within the CT framework, and an expanded program of uncertainty quantification that treats parametrization dependence as an explicit source of epistemic uncertainty, among other issues. We also briefly highlight CT efforts to understand the effects of partial implementations of N$^3$LO corrections into PDF fits, which include benchmark calculations for Higgs and vector-boson processes. We comment on the implications of recent improvements to the CT analysis for precision phenomenology at the LHC and future facilities.
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Submitted 28 December, 2025; v1 submitted 22 December, 2025;
originally announced December 2025.
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Impact of lattice gluon dataset on CTEQ-TEA global PDFs
Authors:
Alim Ablat,
Sayipjamal Dulat,
Tie-Jiun Hou,
Huey-Wen Lin,
Keping Xie,
C. -P. Yuan
Abstract:
We investigate the impact of the latest gluon parton results from lattice QCD on the global parton distribution function (PDF) analysis within the CTEQ-TEA framework. The dependence on PDF parameterization is explored using the CT18As variant, incorporating the ATLAS 7 TeV precision $W,Z$ dataset and introducing more flexible parameters to allow strangeness asymmetry at the starting scale $Q_0$. T…
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We investigate the impact of the latest gluon parton results from lattice QCD on the global parton distribution function (PDF) analysis within the CTEQ-TEA framework. The dependence on PDF parameterization is explored using the CT18As variant, incorporating the ATLAS 7 TeV precision $W,Z$ dataset and introducing more flexible parameters to allow strangeness asymmetry at the starting scale $Q_0$. The interplay between lattice input and collider inclusive jet datasets is examined by including the post-CT18 inclusive jet datasets from recent LHC measurements and/or removing all collider inclusive jet datasets. Finally, we demonstrate several phenomenological implications at the LHC, focusing on gluon-gluon parton luminosity and related processes, such as the production of a Higgs-like scalar, top-quark pairs, and their associated production with an additional jet, Higgs, or $Z$ boson.
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Submitted 14 February, 2025;
originally announced February 2025.
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The impact of LHC precision measurements of inclusive jet and dijet production on the CTEQ-TEA global PDF fit
Authors:
Alim Ablat,
Sayipjamal Dulat,
Tie-Jiun Hou,
Joey Huston,
Pavel Nadolsky,
Ibrahim Sitiwaldi,
Keping Xie,
C. -P. Yuan
Abstract:
In this study, we investigate the impact of new LHC inclusive jet and dijet measurements on parton distribution functions (PDFs) that describe the proton structure, with a particular focus on the gluon distribution at large momentum fraction, $x$, and the corresponding partonic luminosities. We assess constraints from these datasets using next-to-next-to-leading-order (NNLO) theoretical prediction…
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In this study, we investigate the impact of new LHC inclusive jet and dijet measurements on parton distribution functions (PDFs) that describe the proton structure, with a particular focus on the gluon distribution at large momentum fraction, $x$, and the corresponding partonic luminosities. We assess constraints from these datasets using next-to-next-to-leading-order (NNLO) theoretical predictions, accounting for a range of uncertainties from scale dependence and numerical integration. From the scale choices available for the calculations, our analysis shows that the central predictions for inclusive jet production show a smaller scale dependence than dijet production. We examine the relative constraints on the gluon distribution provided by the inclusive jet and dijet distributions and also explore the phenomenological implications for inclusive $H$, $t\bar{t}$, and $t\bar{t}H$ production at the LHC at 14 TeV.
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Submitted 29 November, 2024;
originally announced December 2024.
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Progress in top-quark pair production cross section calculations and impact on parton distribution functions of the proton
Authors:
Alim Ablat,
Sayipjamal Dulat,
Marco Guzzi,
Tie-Jiun Hou,
Nikolaos Kidonakis,
Ibrahim Sitiwaldi,
Alberto Tonero,
Keping Xie,
C. -P. Yuan
Abstract:
We discuss the impact of eligible top-quark pair production differential cross-section measurements at the LHC with a collision energy of 13 TeV on the parton distribution functions (PDFs) of the proton as well as the impact of approximate next-to-next-to-next-to-leading order (aN$^3$LO) QCD corrections combined with next-to-leading order (NLO) electroweak (EW) corrections on $t\bar t$ observables…
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We discuss the impact of eligible top-quark pair production differential cross-section measurements at the LHC with a collision energy of 13 TeV on the parton distribution functions (PDFs) of the proton as well as the impact of approximate next-to-next-to-next-to-leading order (aN$^3$LO) QCD corrections combined with next-to-leading order (NLO) electroweak (EW) corrections on $t\bar t$ observables. We illustrate the effects on the gluon PDF at large $x$ from an optimal baseline selection of data in NNLO global fits, and show comparisons between the theory prediction for $t\bar t$ total and differential cross sections at aN$^3$LO QCD combined with NLO EW and recent measurements from the ATLAS and CMS collaborations at the LHC.
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Submitted 30 October, 2024;
originally announced November 2024.
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The upcoming CTEQ-TEA parton distributions in a nutshell
Authors:
A. Ablat,
A. Courtoy,
S. Dulat,
M. Guzzi,
T. J. Hobbs,
T. -J. Hou,
J. Huston,
P. Nadolsky,
I. Sitiwaldi,
K. Xie,
C. -P. Yuan
Abstract:
We review recent studies by the CTEQ-TEA group toward the development of a new generation of precision parton distribution functions in the nucleon for advanced studies at the high-luminosity LHC and in other experiments. Among several ongoing efforts, we examine sensitivity to the PDFs and mutual compatibility of new measurements in production of Drell-Yan pairs, top-quark pairs, and single-inclu…
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We review recent studies by the CTEQ-TEA group toward the development of a new generation of precision parton distribution functions in the nucleon for advanced studies at the high-luminosity LHC and in other experiments. Among several ongoing efforts, we examine sensitivity to the PDFs and mutual compatibility of new measurements in production of Drell-Yan pairs, top-quark pairs, and single-inclusive jets by the ATLAS, CMS, and LHCb collaborations in the LHC Runs 1 and 2.
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Submitted 20 August, 2024;
originally announced August 2024.
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New results in the CTEQ-TEA global analysis of parton distributions in the nucleon
Authors:
A. Ablat,
A. Courtoy,
S. Dulat,
M. Guzzi,
T. J. Hobbs,
T. -J. Hou,
J. Huston,
K. Mohan,
H. -W. Lin,
P. Nadolsky,
I. Sitiwaldi,
K. Xie,
M. Yan,
C. -P. Yuan
Abstract:
This report summarizes the latest developments in the CTEQ-TEA global analysis of parton distribution functions (PDFs) in the nucleon. The focus is on recent NNLO fits to high-precision LHC data at 8 and 13 TeV, including Drell-Yan, jet, and top-quark pair production, pursued on the way toward the release of the new generation of CTEQ-TEA general-purpose PDFs. The report also discusses advancement…
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This report summarizes the latest developments in the CTEQ-TEA global analysis of parton distribution functions (PDFs) in the nucleon. The focus is on recent NNLO fits to high-precision LHC data at 8 and 13 TeV, including Drell-Yan, jet, and top-quark pair production, pursued on the way toward the release of the new generation of CTEQ-TEA general-purpose PDFs. The report also discusses advancements in statistical and numerical methods for PDF determination and uncertainty quantification, highlighting the importance of robust and replicable uncertainties for high-stakes observables. Additionally, it covers phenomenological studies related to PDF determination, such as the interplay of experimental constraints, exploration of correlations between high-$x$ nucleon sea and low-energy parity-violating measurements, fitted charm in the nucleon, the photon PDF in the neutron, and simultaneous SMEFT-PDF analyses.
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Submitted 22 November, 2024; v1 submitted 7 August, 2024;
originally announced August 2024.
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Exploring the impact of high-precision top-quark pair production data on the structure of the proton at the LHC
Authors:
Alim Ablat,
Marco Guzzi,
Keping Xie,
Sayipjamal Dulat,
Tie-Jiun Hou,
Ibrahim Sitiwaldi,
C. -P. Yuan
Abstract:
The impact of recent LHC top-quark pair production single differential cross section measurements at 13 TeV collision energy on the structure of the proton is explored. In particular, the impact of these high-precision data on the gluon and other parton distribution functions (PDFs) of the proton at intermediate and large partonic momentum fraction $x$ is analyzed. This study extends the CT18 glob…
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The impact of recent LHC top-quark pair production single differential cross section measurements at 13 TeV collision energy on the structure of the proton is explored. In particular, the impact of these high-precision data on the gluon and other parton distribution functions (PDFs) of the proton at intermediate and large partonic momentum fraction $x$ is analyzed. This study extends the CT18 global analysis framework to include these new data. The interplay between top-quark pair and inclusive jet production as well as other processes at the LHC, is studied. In addition, a study of the impact of scale choice on the theory description of the new 13 TeV $t\bar t$ measurements is performed.
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Submitted 11 March, 2024; v1 submitted 20 July, 2023;
originally announced July 2023.
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Precision studies of the post-CT18 LHC Drell-Yan data in the CTEQ-TEA global analysis
Authors:
Ibrahim Sitiwaldi,
Keping Xie,
Alim Ablat,
Sayipjamal Dulat,
Tie-Jiun Hou,
C. - P. Yuan
Abstract:
In this study, we examine closely the impact of the post-CT18 LHC Drell-Yan data on parton distribution functions (PDFs) in the general CTEQ-TEA global analysis framework. We compare the two main theoretical predictions, the MCFM fixed order calculations at next-to-next-to-leading order (NNLO) and the ResBos2 NNLO matched to $q_T$ resummation up to next-to-next-to-next-to-leading logarithmic (N3LL…
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In this study, we examine closely the impact of the post-CT18 LHC Drell-Yan data on parton distribution functions (PDFs) in the general CTEQ-TEA global analysis framework. We compare the two main theoretical predictions, the MCFM fixed order calculations at next-to-next-to-leading order (NNLO) and the ResBos2 NNLO matched to $q_T$ resummation up to next-to-next-to-next-to-leading logarithmic (N3LL) level. We find that the overall inclusive cross sections agree well but the fiducial distributions can differ at a percent level. We mainly discuss the result of the ResBos2 resummation calculation which yields a smaller Monte-Carlo uncertainty, and a better description to the post-CT18 LHC Drell-Yan data. We find that the majority of post-CT18 LHC Drell-Yan data are consistent with the ATLAS 7 TeV $W,Z$ data, which were included in the CT18A, but not CT18, fit and increases the strange quark distribution at the small $x$ region. The noticeable exception is that the ATLAS and LHCb 8 TeV $W$ data pull $d(\bar{d})$ quark PDFs to the opposite direction with respect to the ATLAS 7 TeV $W,Z$ data. The inclusion of these post-CT18 LHC Drell-Yan data sets in the CTEQ-TEA global analysis is to update the CT18 PDFs following similar trends as CT18Z PDFs. The parton luminosities and a few phenomenological implications with the fiducial $W^\pm,Z$ and inclusive $H,t\bar{t},t\bar{t}H$ productions at the 14 TeV LHC, as examples, are presented.
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Submitted 7 June, 2023; v1 submitted 18 May, 2023;
originally announced May 2023.
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Heavy-flavor impact on CTEQ-TEA global QCD analyses
Authors:
Marco Guzzi,
Alim Ablat,
Sayipjamal Dulat,
Tie-Jiun Hou,
Pavel M. Nadolsky,
Ibrahim Sitiwaldi,
Keping Xie,
C. -P. Yuan
Abstract:
We discuss heavy-flavor production at hadron colliders in recent global QCD analyses to determine parton distribution functions (PDFs) in the proton. We discuss heavy-flavor treatments in precision theory predictions at the LHC. In particular, we discuss factorization schemes in presence of heavy flavors in proton-proton collisions, as well as the impact of heavy-flavor production at the LHC on PD…
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We discuss heavy-flavor production at hadron colliders in recent global QCD analyses to determine parton distribution functions (PDFs) in the proton. We discuss heavy-flavor treatments in precision theory predictions at the LHC. In particular, we discuss factorization schemes in presence of heavy flavors in proton-proton collisions, as well as the impact of heavy-flavor production at the LHC on PDFs. We show results of recent updates beyond CT18, the latest global QCD analysis from the CTEQ-TEA group.
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Submitted 22 September, 2022;
originally announced September 2022.
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NNLO constraints on proton PDFs from the SeaQuest and STAR experiments and other developments in the CTEQ-TEA global analysis
Authors:
Marco Guzzi,
T. J. Hobbs,
Tie-Jiun Hou,
Xiaoxian Jing,
Keping Xie,
Aurore Courtoy,
Sayipjamal Dulat,
Jun Gao,
Joey Huston,
Pavel M. Nadolsky,
Carl Schmidt,
Ibrahim Sitiwaldi,
Mengshi Yan,
C. -P. Yuan
Abstract:
We review progress in the global QCD analysis by the CTEQ-TEA group since the publication of CT18 parton distribution functions (PDFs) in the proton. Specifically, we discuss comparisons of CT18 NNLO predictions with the LHC 13 TeV measurements as well as with the FNAL SeaQuest and BNL STAR data on lepton pair production. The specialized CT18X PDFs approximating saturation effects are compared wit…
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We review progress in the global QCD analysis by the CTEQ-TEA group since the publication of CT18 parton distribution functions (PDFs) in the proton. Specifically, we discuss comparisons of CT18 NNLO predictions with the LHC 13 TeV measurements as well as with the FNAL SeaQuest and BNL STAR data on lepton pair production. The specialized CT18X PDFs approximating saturation effects are compared with the CT18sx PDFs obtained using NLL/NLO small-$x$ resummation. Short summaries are presented for the special CT18 parton distributions with fitted charm and with lattice QCD inputs. A recent comparative analysis of the impact of deuteron nuclear effects on the parton distributions by the CTEQ-JLab and CTEQ-TEA groups is summarized.
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Submitted 11 February, 2022; v1 submitted 14 August, 2021;
originally announced August 2021.
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Science Requirements and Detector Concepts for the Electron-Ion Collider: EIC Yellow Report
Authors:
R. Abdul Khalek,
A. Accardi,
J. Adam,
D. Adamiak,
W. Akers,
M. Albaladejo,
A. Al-bataineh,
M. G. Alexeev,
F. Ameli,
P. Antonioli,
N. Armesto,
W. R. Armstrong,
M. Arratia,
J. Arrington,
A. Asaturyan,
M. Asai,
E. C. Aschenauer,
S. Aune,
H. Avagyan,
C. Ayerbe Gayoso,
B. Azmoun,
A. Bacchetta,
M. D. Baker,
F. Barbosa,
L. Barion
, et al. (390 additional authors not shown)
Abstract:
This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams, providing access to those regions in the nucleon…
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This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams, providing access to those regions in the nucleon and nuclei where their structure is dominated by gluons. Moreover, polarized beams in the EIC will give unprecedented access to the spatial and spin structure of the proton, neutron, and light ions. The studies leading to this document were commissioned and organized by the EIC User Group with the objective of advancing the state and detail of the physics program and developing detector concepts that meet the emerging requirements in preparation for the realization of the EIC. The effort aims to provide the basis for further development of concepts for experimental equipment best suited for the science needs, including the importance of two complementary detectors and interaction regions.
This report consists of three volumes. Volume I is an executive summary of our findings and developed concepts. In Volume II we describe studies of a wide range of physics measurements and the emerging requirements on detector acceptance and performance. Volume III discusses general-purpose detector concepts and the underlying technologies to meet the physics requirements. These considerations will form the basis for a world-class experimental program that aims to increase our understanding of the fundamental structure of all visible matter
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Submitted 26 October, 2021; v1 submitted 8 March, 2021;
originally announced March 2021.
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Effect of symmetrical frequency chirp on pair production
Authors:
Kun Wang,
Xuehua Hu,
Sayipjamal Dulat,
B. S. Xie
Abstract:
By using Dirac-Heisenberg-Wigner formalism we study electron-positron pair production for linear, elliptic, nearly circular and circular polarizations of electric fields with symmetrical frequency chirp, and we obtain Momentum spectra and pair yield. The difference of results among polarized fields is obvious for the small chirp. When the chirp parameter increases, the momentum spectra tend to exh…
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By using Dirac-Heisenberg-Wigner formalism we study electron-positron pair production for linear, elliptic, nearly circular and circular polarizations of electric fields with symmetrical frequency chirp, and we obtain Momentum spectra and pair yield. The difference of results among polarized fields is obvious for the small chirp. When the chirp parameter increases, the momentum spectra tend to exhibit the multiphoton pair generation that is characterized by the multi-concentric ring structure. The increase of number density is also remarkable compared to the case of asymmetrical frequency chirp. Note that the dynamically assisted Schwinger Mechanism plays an important role for the enhanced pair production in the symmetrical frequency chirp.
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Submitted 27 February, 2021;
originally announced March 2021.
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Pair production in asymmetric Sauter potential well
Authors:
Adiljan Sawut,
Sayipjamal Dulat,
B. S. Xie
Abstract:
Electron-positron pair production in asymmetric Sauter potential well is studied, where the potential well has been built as the width of the right edge fixed but the left side of the well is changeable at different values. We study the momentum spectrum, the location distribution and the total pair numbers in this case of asymmetric potential well and compare them with the symmetric case. The rel…
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Electron-positron pair production in asymmetric Sauter potential well is studied, where the potential well has been built as the width of the right edge fixed but the left side of the well is changeable at different values. We study the momentum spectrum, the location distribution and the total pair numbers in this case of asymmetric potential well and compare them with the symmetric case. The relationship between created electron energy, the level energy in the bound states and the photon energy in the symmetric potential well is used to the studied problem for the created electrons in the asymmetric potential well and its validity is confirmed by this approximation. By the location distribution of the electrons we have also shown the reason why the momentum spectrum has an optimization in the asymmetric well compared with the symmetric one.
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Submitted 24 February, 2021;
originally announced February 2021.
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Impact of LHCb 13 TeV $W$ and $Z$ pseudo-data on the Parton Distribution Functions
Authors:
Qilin Deng,
Qundong Han,
Hang Yin,
Sayipjamal Dulat,
Tie-Jiun Hou,
C. -P. Yuan
Abstract:
We study the potential of the LHCb 13 TeV single $W^{\pm}$ and $Z$ boson pseudo-data for constraining the parton distribution functions (PDFs) of the proton. As an example, we demonstrate the sensitivity of the LHCb 13 TeV data, collected with integrated luminosities of 5 fb$^{-1}$ and 300 fb$^{-1}$, to reducing the PDF uncertainty bands of the CT14HERA2 PDFs, using the error PDF updating package…
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We study the potential of the LHCb 13 TeV single $W^{\pm}$ and $Z$ boson pseudo-data for constraining the parton distribution functions (PDFs) of the proton. As an example, we demonstrate the sensitivity of the LHCb 13 TeV data, collected with integrated luminosities of 5 fb$^{-1}$ and 300 fb$^{-1}$, to reducing the PDF uncertainty bands of the CT14HERA2 PDFs, using the error PDF updating package {\sc ePump}. The sensitivities of various experimental observables are compared. Generally, sizable reductions in PDF uncertainties can be observed in the 300 fb$^{-1}$ data sample, particularly in the small-$x$ region. The double-differential cross section measurement of $Z$ boson $p_T$ and rapidity can greatly reduce the uncertainty bands of $u$ and $d$ quarks in almost the whole $x$ range, as compared to various single observable measurements.
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Submitted 25 January, 2021; v1 submitted 7 September, 2020;
originally announced September 2020.
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The impact of ATLAS and CMS single differential top-quark pair measurements at $\sqrt{s}=8$ TeV to CTEQ-TEA PDFs
Authors:
Musajan Kadir,
Alim Ablet,
Sayipjamal Dulat,
Tie-Jiun Hou,
Ibrahim Sitiwaldi
Abstract:
By applying the Error PDF Updating Method, we analyze the impact of the absolute and normalized single differential cross-sections for top-quark pair production data from the ATLAS and CMS experiments at the Large Hadron Collider, at a centre-of-mass energy of $\sqrt{s}= 8$ TeV, on the CT14HERA2 PDFs. We find that the top quark pair single differential distributions provide minor constraints on th…
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By applying the Error PDF Updating Method, we analyze the impact of the absolute and normalized single differential cross-sections for top-quark pair production data from the ATLAS and CMS experiments at the Large Hadron Collider, at a centre-of-mass energy of $\sqrt{s}= 8$ TeV, on the CT14HERA2 PDFs. We find that the top quark pair single differential distributions provide minor constraints on the CT14HERA2 gluon PDF when the nominal CT14HERA2 inclusive jet production data are included in the fit. Larger constraints on the gluon distribution are present when the jet data are removed (CT14HERA2mJ) and/or when increased weights are given to the top data in the CT14HERA2 fits. The weighted $t\bar t$ data provide significant constraints on the CT14HERA2mJ gluon PDF, that are comparable to those obtained from inclusive jet production data. Furthermore, we examine the top quark mass sensitivity of the top-quark pair single differential distributions.
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Submitted 23 November, 2020; v1 submitted 30 March, 2020;
originally announced March 2020.
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New CTEQ global analysis of quantum chromodynamics with high-precision data from the LHC
Authors:
Tie-Jiun Hou,
Jun Gao,
T. J. Hobbs,
Keping Xie,
Sayipjamal Dulat,
Marco Guzzi,
Joey Huston,
Pavel Nadolsky,
Jon Pumplin,
Carl Schmidt,
Ibrahim Sitiwaldi,
Daniel Stump,
C. -P. Yuan
Abstract:
We present the new parton distribution functions (PDFs) from the CTEQ-TEA collaboration, obtained using a wide variety of high-precision Large Hadron Collider (LHC) data, in addition to the combined HERA I+II deep-inelastic scattering data set, along with the data sets present in the CT14 global QCD analysis. New LHC measurements in single-inclusive jet production with the full rapidity coverage,…
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We present the new parton distribution functions (PDFs) from the CTEQ-TEA collaboration, obtained using a wide variety of high-precision Large Hadron Collider (LHC) data, in addition to the combined HERA I+II deep-inelastic scattering data set, along with the data sets present in the CT14 global QCD analysis. New LHC measurements in single-inclusive jet production with the full rapidity coverage, as well as production of Drell-Yan pairs, top-quark pairs, and high-$p_T$ $Z$ bosons, are included to achieve the greatest sensitivity to the PDFs. The parton distributions are determined at NLO and NNLO, with each of these PDFs accompanied by error sets determined using the Hessian method. Fast PDF survey techniques, based on the Hessian representation and the Lagrange Multiplier method, are used to quantify the preference of each data set to quantities such as $α_s(m_Z)$, and the gluon and strange quark distributions. We designate the main resulting PDF set as CT18. The ATLAS 7 TeV precision $W/Z$ data are not included in CT18, due to their tension with other data sets in the global fit. Alternate PDF sets are generated including the ATLAS precision 7 TeV $W/Z$ data (CT18A), a new scale choice for low-$x$ DIS data (CT18X), or all of the above with a slightly higher choice for the charm mass (CT18Z). Theoretical calculations of standard candle cross sections at the LHC (such as the $gg$ fusion Higgs boson cross section) are presented.
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Submitted 13 November, 2020; v1 submitted 20 December, 2019;
originally announced December 2019.
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An exploratory study of the impact of CMS double-differential top distributions on the gluon parton distribution function
Authors:
Michał Czakon,
Sayipjamal Dulat,
Tie-Jiun Hou,
Joey Huston,
Alexander Mitov,
Andrew S. Papanastasiou,
Ibrahim Sitiwaldi,
Zhite Yu,
C. --P. Yuan
Abstract:
LHC $t\bar{t}$ data have the potential to provide constraints on the gluon distribution, especially at high $x$, with both ATLAS and CMS performing differential measurements. Recently, CMS has measured double-differential $t\bar{t}$ distributions at 8 TeV. In this paper we examine the impact of this data set on the gluon distribution. To that end we develop novel, double-differential NNLO predicti…
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LHC $t\bar{t}$ data have the potential to provide constraints on the gluon distribution, especially at high $x$, with both ATLAS and CMS performing differential measurements. Recently, CMS has measured double-differential $t\bar{t}$ distributions at 8 TeV. In this paper we examine the impact of this data set on the gluon distribution. To that end we develop novel, double-differential NNLO predictions for that data. No significant impact is found when the CMS data is added to the CT14HERA2 global PDF fit, due to the larger impact of the inclusive jet data from both the Tevatron and the LHC. If the jet data are removed from the fit, then an impact is observed. If the CMS data is scaled by a larger weight, representing the greater statistical power of the jet data, a roughly equal impact on the gluon distribution is observed for the $t\bar{t}$ as for the inclusive jet data. For data samples with higher integrated luminosity at 13 TeV, a more significant impact of the double-differential $t\bar{t}$ data may be observed.
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Submitted 23 November, 2020; v1 submitted 18 December, 2019;
originally announced December 2019.
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Chirp effects on pair production in oscillating electric fields with spatial inhomogeneity
Authors:
Mamutjan Ababekri,
Sayipjamal Dulat,
B. S. Xie,
Jun Zhang
Abstract:
Dirac-Heisenberg-Wigner formalism is used to study chirp effects on the vacuum pair creation under inhomogeneous electric fields. For rapidly oscillating electric fields, the particle momentum spectrum is sensitive to both of the spatial scale and the chirp parameter, and the external field width has less significant effect for the maximally large chirp. For slowly oscillating electric fields, chi…
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Dirac-Heisenberg-Wigner formalism is used to study chirp effects on the vacuum pair creation under inhomogeneous electric fields. For rapidly oscillating electric fields, the particle momentum spectrum is sensitive to both of the spatial scale and the chirp parameter, and the external field width has less significant effect for the maximally large chirp. For slowly oscillating electric fields, chirp effects could be identified at large spatial extents and the carrier phase plays a significant role reflecting chirp effects even at small spatial scales. We also notice that, the local density approximation holds for all external field profiles considered in this work at the quasihomogeneous limit allowing one to use arguments from homogeneous scenarios to analyze inhomogeneous results.
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Submitted 20 February, 2020; v1 submitted 6 December, 2019;
originally announced December 2019.
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LHC and DIS experimental data in the CT18(Z) global QCD analysis
Authors:
Tie-Jiun Hou,
Keping Xie,
Jun Gao,
Sayipjamal Dulat,
Marco Guzzi,
T. J. Hobbs,
Joey Huston,
Pavel Nadolsky,
Jon Pumplin,
Carl Schmidt,
Ibrahim Sitiwaldi,
Dan Stump,
Bo-Ting Wang,
C. -P. Yuan
Abstract:
We discuss implementation of the LHC experimental data sets in the new CT18 global analysis of quantum chromodynamics (QCD) at the next-to-next-leading order of the QCD coupling strength. New methodological developments in the fitting methodology are discussed. Behavior of the CT18 NNLO PDFs for the conventional and "saturation-inspired" factorization scales in deep-inelastic scattering is reviewe…
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We discuss implementation of the LHC experimental data sets in the new CT18 global analysis of quantum chromodynamics (QCD) at the next-to-next-leading order of the QCD coupling strength. New methodological developments in the fitting methodology are discussed. Behavior of the CT18 NNLO PDFs for the conventional and "saturation-inspired" factorization scales in deep-inelastic scattering is reviewed. Four new families of (N)NLO CTEQ-TEA PDFs are presented: CT18, A, X, and Z.
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Submitted 29 August, 2019;
originally announced September 2019.
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Progress in the CTEQ-TEA NNLO global QCD analysis
Authors:
Tie-Jiun Hou,
Keping Xie,
Jun Gao,
Sayipjamal Dulat,
Marco Guzzi,
T. J. Hobbs,
Joey Huston,
Pavel Nadolsky,
Jon Pumplin,
Carl Schmidt,
Ibrahim Sitiwaldi,
Dan Stump,
C. -P. Yuan
Abstract:
We present the new CTEQ-TEA global analysis of quantum chromodynamics (QCD). In this analysis, parton distribution functions (PDFs) of the nucleon are determined within the Hessian method at the next-to-next-to-leading order (NNLO) in perturbative QCD, based on the most recent measurements from the Large Hadron Collider (LHC) and a variety of world collider data. Because of difficulties in fitting…
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We present the new CTEQ-TEA global analysis of quantum chromodynamics (QCD). In this analysis, parton distribution functions (PDFs) of the nucleon are determined within the Hessian method at the next-to-next-to-leading order (NNLO) in perturbative QCD, based on the most recent measurements from the Large Hadron Collider (LHC) and a variety of world collider data. Because of difficulties in fitting both the ATLAS 7 and 8 TeV $W$ and $Z$ vector boson production cross section data, we present four families of (N)NLO CTEQ-TEA PDFs, named CT18, A, X and Z PDFs, respectively. We study the impact of the CT18 family of PDFs on the theoretical predictions of standard candle cross sections at the LHC.
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Submitted 29 August, 2019;
originally announced August 2019.
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New CTEQ Global Analysis with High Precision Data from the LHC
Authors:
Tie-Jiun Hou,
Keping Xie,
Jun Gao,
Sayipjamal Dulat,
Marco Guzzi,
T. J. Hobbs,
Joey Huston,
Pavel Nadolsky,
Jon Pumplin,
Carl Schmidt,
Ibrahim Sitiwaldi,
Dan Stump,
C. -P. Yuan
Abstract:
We present the new CTEQ-TEA global analysis of quantum chromodynamics (QCD). In this analysis, parton distribution functions (PDFs) of the nucleon are determined within the Hessian method at the next-to-next-to leading order (NNLO) in perturbative QCD, based on the most recent measurements from the Large Hadron Collider (LHC) and a variety of world collider data. Because of difficulties in fitting…
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We present the new CTEQ-TEA global analysis of quantum chromodynamics (QCD). In this analysis, parton distribution functions (PDFs) of the nucleon are determined within the Hessian method at the next-to-next-to leading order (NNLO) in perturbative QCD, based on the most recent measurements from the Large Hadron Collider (LHC) and a variety of world collider data. Because of difficulties in fitting both the ATLAS 7 and 8 TeV $W$ and $Z$ vector boson production cross section data, we present two families of PDFs, named CT18 and CT18$Z$ PDFs, respectively, without and with the ATLAS 7 TeV $W$ and $Z$ measurements. We study the impact of the CT18 family of PDFs on the theoretical predictions of standard candle cross sections at the LHC.
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Submitted 29 August, 2019;
originally announced August 2019.
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Impact of LHC top-quark pair measurements to CTEQ-TEA PDF analysis
Authors:
Orkash Amat,
Michał Czakon,
Sayipjamal Dulat,
Tie-Jiun Hou,
Joey Huston,
Alexander Mitov,
Andrew S. ~Papanastasiou,
Carl Schmidt,
Ibrahim Sitiwaldi,
Keping Xie,
Zhite Yu,
C. -P. Yuan
Abstract:
Detailed studies have been carried out on the impact of the LHC top quark pair production data on gluon PDF, in the context of the CTEQ-TEA global PDF fit, with the ePump-updating method. The considered $t\bar{t}$ data include single differential distributions from ATLAS and double differential distributions from CMS, both at 8 TeV. All analyses have been carried out at the NNLO, using fastNNLO ta…
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Detailed studies have been carried out on the impact of the LHC top quark pair production data on gluon PDF, in the context of the CTEQ-TEA global PDF fit, with the ePump-updating method. The considered $t\bar{t}$ data include single differential distributions from ATLAS and double differential distributions from CMS, both at 8 TeV. All analyses have been carried out at the NNLO, using fastNNLO tables. We show that the sensitivity per data point of the LHC $t\bar{t}$ data is similar to that of jet data, as included in the CT14HERA2 fit, while the total sensitivity of the present $t\bar{t}$ data is not as large as the jet data because of the much smaller number of $t\bar{t}$ data points in the presently available data.
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Submitted 18 August, 2019;
originally announced August 2019.
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QCD analysis of CMS W + charm measurements at LHC with \sqrt s = 7TeV and implications for the strange PDF
Authors:
Nijat Yalkun,
Sayipjamal Dulat
Abstract:
We calculate cross-sections and cross-section ratios of a charm quark production in association with a $W$ gauge boson at next-to-leading order QCD using MadGraph and CT10NNLO, CT14NNLO, and MSTW2008NNLO PDFs. We compare the results with measurements from the CMS detector at the LHC at a center-of-mass energy of 7TeV. Moreover, we calculate absolute and normalized differential cross-sections as we…
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We calculate cross-sections and cross-section ratios of a charm quark production in association with a $W$ gauge boson at next-to-leading order QCD using MadGraph and CT10NNLO, CT14NNLO, and MSTW2008NNLO PDFs. We compare the results with measurements from the CMS detector at the LHC at a center-of-mass energy of 7TeV. Moreover, we calculate absolute and normalized differential cross-sections as well as differential cross-section ratios as a function of the lepton pseudorapidity from the $W$ boson decay. The correlation between the CT14NNLO PDFs and predictions for $W+$ charm data are studied as well. Furthermore, by employing the error PDF updating method proposed by the CTEQ-TEA group, we update CT14NNLO PDFs, and analyze the impact of CMS 7TeV $W+$ charm production data to the original CT14NNLO PDFs. By comparison of the $g(x,Q)$, $s(x,Q)$, $u(x,Q)$, $d(x,Q)$, $\bar u(x,Q)$, and $\bar d(x,Q)$ PDFs at $Q=1.3$ GeV and $Q = 100$ GeV for the CT14NNLO and CT14NNLO+Wc, we see that the error band of the $s(x,Q)$ PDF is reduced in the region $x<0.4$, and the error band of $g(x,Q)$ PDF is also slightly reduced in the region $0.01 < x < 0.1$.
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Submitted 24 November, 2019; v1 submitted 31 July, 2019;
originally announced August 2019.
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Updating and Optimizing Error PDFs in the Hessian Approach. Part II
Authors:
Tie-Jiun Hou,
Zhite Yu,
Sayipjamal Dulat,
Carl Schmidt,
C. -P. Yuan
Abstract:
In an earlier publication, we introduced the software package, {\tt \texttt{ePump}} (error PDF Updating Method Package), that can be used to update or optimize a set of parton distribution functions (PDFs), including the best-fit PDF set and Hessian eigenvector pairs of PDF sets (i.e., error PDFs), and to update any other set of observables, in the Hessian approach. Here, we validate the {\tt \tex…
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In an earlier publication, we introduced the software package, {\tt \texttt{ePump}} (error PDF Updating Method Package), that can be used to update or optimize a set of parton distribution functions (PDFs), including the best-fit PDF set and Hessian eigenvector pairs of PDF sets (i.e., error PDFs), and to update any other set of observables, in the Hessian approach. Here, we validate the {\tt \texttt{ePump}} program with a detailed comparison against a full global analysis, and we demonstrate the potential of {\tt \texttt{ePump}} by presenting selected phenomenological applications relevant to the Large Hadron Collider. For example, we use the package to estimate the impact of the recent LHC data of the measurements of $W$, $Z$ boson and top quark pair differential distributions on the CT14HERA2 PDFs.
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Submitted 2 December, 2019; v1 submitted 28 July, 2019;
originally announced July 2019.
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CTEQ-TEA parton distribution functions with intrinsic charm
Authors:
Marco Guzzi,
Tie-Jiun Hou,
Sayipjamal Dulat,
Jun Gao,
Joey Huston,
Pavel Nadolsky,
Carl Schmidt,
Jan Winter,
Keping Xie,
C. -P. Yuan
Abstract:
The possibility of a (sizable) nonperturbative contribution to the charm parton distribution function (PDF) in a nucleon is investigated together with theoretical issues arising in its interpretation. Results from the global PDF analysis are presented. The separation of the universal component of the nonperturbative charm from the rest of the radiative contributions is discussed and the potential…
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The possibility of a (sizable) nonperturbative contribution to the charm parton distribution function (PDF) in a nucleon is investigated together with theoretical issues arising in its interpretation. Results from the global PDF analysis are presented. The separation of the universal component of the nonperturbative charm from the rest of the radiative contributions is discussed and the potential impact of a nonperturbative charm PDF on LHC scattering processes is illustrated. An estimate of nonperturbative charm magnitude in the CT14 and CT14HERA2 global QCD analyses at the next-to-next-to leading order (NNLO) in the QCD coupling strength is given by including the latest experimental data from HERA and the Large Hadron Collider (LHC). A comparison between different models of intrinsic charm is shown and prospects for standard candle observables at the LHC are illustrated.
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Submitted 29 September, 2018;
originally announced October 2018.
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Next-to-leading order QCD and electroweak corrections to Higgs-strahlung processes at the LHC
Authors:
Pazilet Obul,
Sayipjamal Dulat,
Tie-Jiun Hou,
Ablikim Tursun,
Nijat Yalkun
Abstract:
In this paper we calculate the total and fiducial cross sections as well as differential distributions for the Higgs-strahlung or VH process $p p \to VH \to lν_l/l^- l^+ + H$, (V = W or Z, l=e,$μ$) including QCD and electro-weak corrections up to next-to-leading order before and after reweighting photon PDFs of NNPDF2.3qed, NNPDF3.0qed, MRST2004qed, CT14QEDinc, and LUXqed at the LHC with 13 TeV an…
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In this paper we calculate the total and fiducial cross sections as well as differential distributions for the Higgs-strahlung or VH process $p p \to VH \to lν_l/l^- l^+ + H$, (V = W or Z, l=e,$μ$) including QCD and electro-weak corrections up to next-to-leading order before and after reweighting photon PDFs of NNPDF2.3qed, NNPDF3.0qed, MRST2004qed, CT14QEDinc, and LUXqed at the LHC with 13 TeV and Higgs boson mass $\ M_{H}=125$ GeV. The predictions from the various photon PDFs before and after reweighting against each other are in good agreement. The photon PDF uncertainties of the photon-induced cross sections decrease significantly with the reweighting PDFs.
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Submitted 10 November, 2018; v1 submitted 21 January, 2018;
originally announced January 2018.
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CT14 Intrinsic Charm Parton Distribution Functions from CTEQ-TEA Global Analysis
Authors:
Tie-Jiun Hou,
Sayipjamal Dulat,
Jun Gao,
Marco Guzzi,
Joey Huston,
Pavel Nadolsky,
Carl Schmidt,
Jan Winter,
Keping Xie,
C. -P. Yuan
Abstract:
We investigate the possibility of a (sizable) nonperturbative contribution to the charm parton distribution function (PDF) in a nucleon, theoretical issues arising in its interpretation, and its potential impact on LHC scattering processes. The "fitted charm" PDF obtained in various QCD analyses contains a process-dependent component that is partly traced to power-suppressed radiative contribution…
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We investigate the possibility of a (sizable) nonperturbative contribution to the charm parton distribution function (PDF) in a nucleon, theoretical issues arising in its interpretation, and its potential impact on LHC scattering processes. The "fitted charm" PDF obtained in various QCD analyses contains a process-dependent component that is partly traced to power-suppressed radiative contributions in DIS and is generally different at the LHC. We discuss separation of the universal component of the nonperturbative charm from the rest of the radiative contributions and estimate its magnitude in the CT14 global QCD analysis at the next-to-next-to leading order in the QCD coupling strength, including the latest experimental data from HERA and the Large Hadron Collider. Models for the nonperturbative charm PDF are examined as a function of the charm quark mass and other parameters. The prospects for testing these models in the associated production of a Z boson and a charm jet at the LHC are studied under realistic assumptions, including effects of the final-state parton showering.
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Submitted 25 January, 2018; v1 submitted 3 July, 2017;
originally announced July 2017.
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CTEQ-TEA parton distribution functions and HERA Run I and II combined data
Authors:
Tie-Jiun Hou,
Sayipjamal Dulat,
Jun Gao,
Marco Guzzi,
Joey Huston,
Pavel Nadolsky,
Jon Pumplin,
Carl Schmidt,
Daniel Stump,
C. -P. Yuan
Abstract:
We analyze the impact of the recent HERA run I+II combination of inclusive deep inelastic scattering cross-section data on the CT14 global analysis of PDFs. New PDFs at NLO and NNLO, called CT14$_{\textrm{HERA2}}$, are obtained by a refit of the CT14 data ensembles, in which the HERA run I combined measurements are replaced by the new HERA run I+II combination. The CT14 functional parametrization…
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We analyze the impact of the recent HERA run I+II combination of inclusive deep inelastic scattering cross-section data on the CT14 global analysis of PDFs. New PDFs at NLO and NNLO, called CT14$_{\textrm{HERA2}}$, are obtained by a refit of the CT14 data ensembles, in which the HERA run I combined measurements are replaced by the new HERA run I+II combination. The CT14 functional parametrization of PDFs is flexible enough to allow good descriptions of different flavor combinations, so we use the same parametrization for CT14$_{\textrm{HERA2}}$ but with an additional shape parameter for describing the strange quark PDF. We find that the HERA I+II data can be fit reasonably well, and both CT14 and CT14$_{\textrm{HERA2}}$ PDFs can describe equally well the non-HERA data included in our global analysis. Because the CT14 and CT14$_{\textrm{HERA2}}$ PDFs agree well within the PDF errors, we continue to recommend CT14 PDFs for the analysis of LHC Run 2 experiments.
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Submitted 31 March, 2017; v1 submitted 26 September, 2016;
originally announced September 2016.
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Reconstruction of Monte Carlo replicas from Hessian parton distributions
Authors:
Tie-Jiun Hou,
Jun Gao,
Joey Huston,
Pavel Nadolsky,
Carl Schmidt,
Daniel Stump,
Bo-Ting Wang,
Ke-Ping Xie,
Sayipjamal Dulat,
Jon Pumplin,
C. -P. Yuan
Abstract:
We explore connections between two common methods for quantifying the uncertainty in parton distribution functions (PDFs), based on the Hessian error matrix and Monte-Carlo sampling. CT14 parton distributions in the Hessian representation are converted into Monte-Carlo replicas by a numerical method that reproduces important properties of CT14 Hessian PDFs: the asymmetry of CT14 uncertainties and…
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We explore connections between two common methods for quantifying the uncertainty in parton distribution functions (PDFs), based on the Hessian error matrix and Monte-Carlo sampling. CT14 parton distributions in the Hessian representation are converted into Monte-Carlo replicas by a numerical method that reproduces important properties of CT14 Hessian PDFs: the asymmetry of CT14 uncertainties and positivity of individual parton distributions. The ensembles of CT14 Monte-Carlo replicas constructed this way at NNLO and NLO are suitable for various collider applications, such as cross section reweighting. Master formulas for computation of asymmetric standard deviations in the Monte-Carlo representation are derived. A correction is proposed to address a bias in asymmetric uncertainties introduced by the Taylor series approximation. A numerical program is made available for conversion of Hessian PDFs into Monte-Carlo replicas according to normal, log-normal, and Watt-Thorne sampling procedures.
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Submitted 7 March, 2017; v1 submitted 20 July, 2016;
originally announced July 2016.
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Implication of CMS data on photon PDFs
Authors:
Pazilet Obul,
Mamut Ababekri,
Sayipjamal Dulat,
Joshua Isaacson,
Carl Schmidt,
C. -P. Yuan
Abstract:
As part of a recent analysis of exclusive two-photon production of W+ W- pairs at the LHC, the CMS experiment used di-lepton data to obtain an "effective" photon-photon luminosity. We show how the CMS analysis on their 8 TeV data, along with some assumptions about the likelihood for events in which the proton breaks up to pass the selection criteria, can be used to significantly constrain the phot…
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As part of a recent analysis of exclusive two-photon production of W+ W- pairs at the LHC, the CMS experiment used di-lepton data to obtain an "effective" photon-photon luminosity. We show how the CMS analysis on their 8 TeV data, along with some assumptions about the likelihood for events in which the proton breaks up to pass the selection criteria, can be used to significantly constrain the photon parton distribution functions, such as those from the CTEQ, MRST, and NNPDF collaborations. We compare the data with predictions using these photon distributions, as well as the new LUXqed photon distribution. We study the impact of including these data on the NNPDF2.3QED, NNPDF3.0QED and CT14QEDinc fits. We find that these data place a usefil and complementary cross-check on the photon distribution, which is consistent with LUXqed prediction while suggesting that the NNPDF photon error band should be significantly reduced. Additionally, we propose a simple model for describing the two-photon production of W+ W- at the LHC. Using this model, we constrain the amount of inelastic photon that remains after the experimental cuts are applied.
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Submitted 7 November, 2018; v1 submitted 15 March, 2016;
originally announced March 2016.
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New parton distribution functions from a global analysis of quantum chromodynamics
Authors:
Sayipjamal Dulat,
Tie Jiun Hou,
Jun Gao,
Marco Guzzi,
Joey Huston,
Pavel Nadolsky,
Jon Pumplin,
Carl Schmidt,
Daniel Stump,
C. P. Yuan
Abstract:
We present new parton distribution functions (PDFs) up to next-to-next-to-leading order (NNLO) from the CTEQ-TEA global analysis of quantum chromodynamics. These differ from previous CT PDFs in several respects, including the use of data from LHC experiments and the new D0 charged lepton rapidity asymmetry data, as well as the use of more flexible parametrization of PDFs that, in particular, allow…
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We present new parton distribution functions (PDFs) up to next-to-next-to-leading order (NNLO) from the CTEQ-TEA global analysis of quantum chromodynamics. These differ from previous CT PDFs in several respects, including the use of data from LHC experiments and the new D0 charged lepton rapidity asymmetry data, as well as the use of more flexible parametrization of PDFs that, in particular, allows a better fit to different combinations of quark flavors. Predictions for important LHC processes, especially Higgs boson production at 13 TeV, are presented. These CT14 PDFs include a central set and error sets in the Hessian representation. For completeness, we also present the CT14 PDFs determined at the leading order (LO) and the next-to-leading order (NLO) in QCD. Besides these general-purpose PDF sets, we provide a series of (N)NLO sets with various $α_s$ values and additional sets in general-mass variable flavor number (GM-VFN) schemes, to deal with heavy partons, with up to 3, 4, and 6 active flavors.
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Submitted 7 March, 2016; v1 submitted 24 June, 2015;
originally announced June 2015.
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Higgs Boson Cross Section from CTEQ-TEA Global Analysis
Authors:
Sayipjamal Dulat,
Tie-Jiun Hou,
Jun Gao,
Joey Huston,
Pavel Nadolsky,
Jon Pumplin,
Carl Schmidt,
Daniel Stump,
C. -P. Yuan
Abstract:
We study the uncertainties of the Higgs boson production cross section through the gluon fusion subprocess at the LHC (with $\sqrt s=7, 8$ and $14$ TeV) arising from the uncertainties of the parton distribution functions (PDFs) and of the value of the strong coupling constant $α_s(M_Z)$. These uncertainties are computed by two complementary approaches, based on the Hessian and the Lagrange Multipl…
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We study the uncertainties of the Higgs boson production cross section through the gluon fusion subprocess at the LHC (with $\sqrt s=7, 8$ and $14$ TeV) arising from the uncertainties of the parton distribution functions (PDFs) and of the value of the strong coupling constant $α_s(M_Z)$. These uncertainties are computed by two complementary approaches, based on the Hessian and the Lagrange Multiplier methods within the CTEQ-TEA global analysis framework. We find that their predictions for the Higgs boson cross section are in good agreement. Furthermore, the result of the Lagrange Multiplier method supports the prescriptions we have previously provided for using the Hessian method to calculate the combined PDF and $α_s$ uncertainties, and to estimate the uncertainties at the $68\%$ confidence level by scaling them from the $90\%$ confidence level.
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Submitted 19 August, 2014; v1 submitted 28 October, 2013;
originally announced October 2013.
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Intrinsic Charm Parton Distribution Functions from CTEQ-TEA Global Analysis
Authors:
Sayipjamal Dulat,
Tie-Jiun Hou,
Jun Gao,
Joey Huston,
Jon Pumplin,
Carl Schmidt,
Daniel Stump,
C. -P. Yuan
Abstract:
We study the possibility of intrinsic (non-perturbative) charm in parton distribution functions (PDF) of the proton, within the context of the CT10 next-to-next-to-leading order (NNLO) global analysis. Three models for the intrinsic charm (IC) quark content are compared: (i) $\hat{c}(x) = 0$ (zero-IC model); (ii) $\hat{c}(x)$ is parametrized by a valence-like parton distribution (BHPS model); (iii…
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We study the possibility of intrinsic (non-perturbative) charm in parton distribution functions (PDF) of the proton, within the context of the CT10 next-to-next-to-leading order (NNLO) global analysis. Three models for the intrinsic charm (IC) quark content are compared: (i) $\hat{c}(x) = 0$ (zero-IC model); (ii) $\hat{c}(x)$ is parametrized by a valence-like parton distribution (BHPS model); (iii) $\hat{c}(x)$ is parametrized by a sea-like parton distribution (SEA model). In these models, the intrinsic charm content, $\hat{c}(x)$, is included in the charm PDF at the matching scale $Q_c=m_c=1.3$ GeV. The best fits to data are constructed and compared. Correlations between the value of $m_c$ and the amount of IC are also considered.
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Submitted 19 August, 2014; v1 submitted 30 August, 2013;
originally announced September 2013.
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$π^+π^+$ and $π^+π^-$ colliding in noncommutative space
Authors:
Jianhua wang,
Kang Li,
Sayipjamal Dulat,
Yi Yuan,
Kai Ma
Abstract:
By studying the scattering process of scalar particle pion on the noncommutative scalar quantum electrodynamics, the non-commutative amendment of differential scattering cross-section is found, which is dependent of polar-angle and the results are significantly different from that in the commutative scalar quantum electrodynamics, particularly when $\cosθ\sim \pm 1$. The non-commutativity of space…
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By studying the scattering process of scalar particle pion on the noncommutative scalar quantum electrodynamics, the non-commutative amendment of differential scattering cross-section is found, which is dependent of polar-angle and the results are significantly different from that in the commutative scalar quantum electrodynamics, particularly when $\cosθ\sim \pm 1$. The non-commutativity of space is expected to be explored at around $Λ_{NC}\sim$TeV.
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Submitted 8 March, 2012;
originally announced May 2012.
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Proposal and theoretical formalism for studying baryon radiative decays from J/ψ\to B^*\bar B + \bar{B^*}B \to γB\bar B
Authors:
Sayipjamal Dulat,
Jia-Jun Wu,
B. S. Zou
Abstract:
With accumulation of high statistics data at BESIII, one may study many new interesting channels. Among them, J/ψ\to B^*\bar B + \bar{B^*}B \to γB\bar B processes may provide valuable information of the radiative decays of the excited baryons (N^*,Λ^*,Σ^*,Ξ^*), and may shed light on their internal quark-gluon structure. Our estimation for the branching ratios of the nucleon excitations N^*(1440),…
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With accumulation of high statistics data at BESIII, one may study many new interesting channels. Among them, J/ψ\to B^*\bar B + \bar{B^*}B \to γB\bar B processes may provide valuable information of the radiative decays of the excited baryons (N^*,Λ^*,Σ^*,Ξ^*), and may shed light on their internal quark-gluon structure. Our estimation for the branching ratios of the nucleon excitations N^*(1440), N^*(1535) and N^*(1520) from the reaction J/ψ\to N^*\bar p + \bar N^* p \to γp\bar p, indicates that these processes can be studied at BESIII with 10^{10} J/ψevents. Explicit theoretical formulae for the partial wave analysis (PWA) of the J/ψ\to B^*\bar B +\bar B^* B with B^*\to B γand \bar B^*\to \bar Bγwithin covariant L-S Scheme are provided.
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Submitted 29 March, 2011;
originally announced March 2011.
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Further evidence for the $Σ^{*}$ resonance with $J^P=1/2^-$ around 1380 MeV
Authors:
Jia-Jun Wu,
S. Dulat,
B. S. Zou
Abstract:
The unquenched quark models predict the new particle $Σ^*$ with spin parity $J^P=1/2^-$ and its mass is around the well established $Σ^*(1385)$ with $J^P=3/2^+$. Here by using the effective Lagrangian approach we study \kp\ reaction at the range of $Λ^{*}(1520)$ peak, comparing the resulting total cross section, and $π^+π^-$, $Λπ^+$, $Λπ^-$ invariant squared mass distributions for various incide…
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The unquenched quark models predict the new particle $Σ^*$ with spin parity $J^P=1/2^-$ and its mass is around the well established $Σ^*(1385)$ with $J^P=3/2^+$. Here by using the effective Lagrangian approach we study \kp\ reaction at the range of $Λ^{*}(1520)$ peak, comparing the resulting total cross section, and $π^+π^-$, $Λπ^+$, $Λπ^-$ invariant squared mass distributions for various incident $K^-$ momenta, as well as the production angular distribution of the $Λ$ with the data from the Lawrence Berkeley Laboratory 25-inch hydrogen bubble chamber, we find that, apart from the existing resonance $Σ^{*}(1385)$ with $J^P=3/2^+$, there is a strong evidence for the existence of the new resonance $Σ^{*}$ with $J^P=1/2^-$ around 1380 MeV. Higher statistic data on relevant reactions are needed to clarify the situation.
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Submitted 7 September, 2009;
originally announced September 2009.
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Evidence for a new $Σ^{*}$ resonance with $J^P=1/2^-$ in the old data of $K^-p\toΛπ^+π^-$ reaction
Authors:
Jia-Jun Wu,
S. Dulat,
B. S. Zou
Abstract:
Distinctive patterns are predicted by quenched quark models and unquenched quark models for the lowest SU(3) baryon nonet with spin parity $J^P=1/2^-$. While the quenched quark models predict the lowest $1/2^-$ $Σ^*$ resonance to be above 1600 MeV, the unquenched quark models predict it to be around $Σ^*(1385)$ energy. Here we re-examine some old data of the $\kp \to \la$ reaction and find that…
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Distinctive patterns are predicted by quenched quark models and unquenched quark models for the lowest SU(3) baryon nonet with spin parity $J^P=1/2^-$. While the quenched quark models predict the lowest $1/2^-$ $Σ^*$ resonance to be above 1600 MeV, the unquenched quark models predict it to be around $Σ^*(1385)$ energy. Here we re-examine some old data of the $\kp \to \la$ reaction and find that besides the well established $Σ^{*}(1385)$ with $J^P=3/2^+$, there is indeed some evidence for the possible existence of a new $Σ^{*}$ resonance with $J^P=1/2^-$ around the same mass but with broader decay width. Higher statistic data on relevant reactions are needed to clarify the situation.
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Submitted 10 July, 2009; v1 submitted 22 June, 2009;
originally announced June 2009.
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Covariant tensor formalism for partial wave analyses of $ψ$ decays into $γB\bar B$, $γγV$ and $ψ(2S)\toγχ_{c0,1,2}$ with $χ_{c0,1,2}\to K\bar K π^+π^- $ and $2π^+2π^-$
Authors:
Sayipjamal Dulat,
Bing-Song Zou
Abstract:
With accumulation of high statistics data at BES and CLEO-c, many new interesting channels can get enough statistics for partial wave analysis (PWA). Among them, $ψ\to γp\bar p, γΛ\bar Λ, γΣ\barΣ, γΞ\bar Ξ$ channels provide a good place for studying baryon-antibaryon interactions; the double radiative decays $ψ\toγγV$ with $V\equiv ρ,ω,φ$ have a potential to provide information on the flavor con…
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With accumulation of high statistics data at BES and CLEO-c, many new interesting channels can get enough statistics for partial wave analysis (PWA). Among them, $ψ\to γp\bar p, γΛ\bar Λ, γΣ\barΣ, γΞ\bar Ξ$ channels provide a good place for studying baryon-antibaryon interactions; the double radiative decays $ψ\toγγV$ with $V\equiv ρ,ω,φ$ have a potential to provide information on the flavor content of any meson resonances (R) with positive charge parity ($C=+$) and mass above 1 GeV through $ψ\toγR \toγγV$; $ψ(2S)\toγχ_{c0,1,2}$ with $χ_{c0,1,2}\to K\bar K π^+π^- $ and $2π^+2π^-$ decays are good processes to study $χ_{cJ}$ charmonium decays. Using the covariant tensor formalism, here we provide theoretical PWA formulae for these channels.
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Submitted 7 August, 2005;
originally announced August 2005.
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Covariant tensor formalism for partial wave analyses of $ψ$ decays into $γB\bar B$
Authors:
Sayipjamal Dulat,
BoChao Liu,
BingSong Zou,
JiMin Wu
Abstract:
Recently BES2 collaboration observed an enhancement near the $p\bar p$ invariant mass spectrum. Using the covariant tensor formalism, here we provide theoretical formulae for the partial wave analysis (PWA) of the $ψ$ radiative decay channels $ψ\to γp\bar p, γΛ\bar Λ, γΣ\barΣ, γΞ\bar Ξ$ . By performing the Monte Carlo simulation, we give the angular distributions for the photon and proton in the…
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Recently BES2 collaboration observed an enhancement near the $p\bar p$ invariant mass spectrum. Using the covariant tensor formalism, here we provide theoretical formulae for the partial wave analysis (PWA) of the $ψ$ radiative decay channels $ψ\to γp\bar p, γΛ\bar Λ, γΣ\barΣ, γΞ\bar Ξ$ . By performing the Monte Carlo simulation, we give the angular distributions for the photon and proton in the process of $J/ψ\to γp\bar p$, which may serve as a useful reference for the future PWA on these channels.
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Submitted 12 March, 2004;
originally announced March 2004.
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Covariant tensor formalism for partial wave analyses of $ψ$ decays into $γγV$
Authors:
Sayipjamal Dulat,
Bing-Song Zou,
Ji-Min Wu
Abstract:
The double radiative decays $ψ\toγγV$ with $V\equiv ρ,ω,φ$ have a potential to provide information on the flavor content of any meson resonances (R) with positive charge parity ($C=+$) and mass above 1 GeV through $ψ\toγR \toγγV$. To get the information, one needs both high statistic data and partial wave analysis (PWA). While high statistic data will be available soon at CLEO-c and BES-III, her…
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The double radiative decays $ψ\toγγV$ with $V\equiv ρ,ω,φ$ have a potential to provide information on the flavor content of any meson resonances (R) with positive charge parity ($C=+$) and mass above 1 GeV through $ψ\toγR \toγγV$. To get the information, one needs both high statistic data and partial wave analysis (PWA). While high statistic data will be available soon at CLEO-c and BES-III, here we provide theoretical PWA formulae for these $ψ$ double radiative decay channels in the covariant tensor formalism.
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Submitted 9 August, 2005; v1 submitted 9 March, 2004;
originally announced March 2004.
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Scalar charmonium and glueball mixing in $e^+ e^-\to J/ψX$
Authors:
S. Dulat,
K. Hagiwara,
Z. -H. Lin
Abstract:
We study the possibility of the scalar charmonium and glueball mixing in $e^+ e^-$ annihilation at $\sqrt{s}=10.6$ GeV. The effects can be used to explain the unexpected large cross section ($12\pm 4$ fb) and the anomalous angular distribution ($α= -1.1^{+0.8}_{-0.6}$) of the exclusive $e^+e^-\to J/ψχ_{c0}$ process observed by Belle experiments at KEKB. We calculate the helicity amplitudes for t…
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We study the possibility of the scalar charmonium and glueball mixing in $e^+ e^-$ annihilation at $\sqrt{s}=10.6$ GeV. The effects can be used to explain the unexpected large cross section ($12\pm 4$ fb) and the anomalous angular distribution ($α= -1.1^{+0.8}_{-0.6}$) of the exclusive $e^+e^-\to J/ψχ_{c0}$ process observed by Belle experiments at KEKB. We calculate the helicity amplitudes for the process $e^+ e^- \to J/ψH(0^{++})$ in NRQCD, where $H(0^{++})$ is the mixed state. We present a detailed analysis on the total cross section and various angular asymmetries which could be useful to reveal the existence of the scalar glueball state.
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Submitted 23 August, 2004; v1 submitted 23 February, 2004;
originally announced February 2004.