-
Techniques for mass peak reconstruction in Searches for Long-Lived Heavy Neutral Leptons Decaying to a Lepton and a \(ρ\) Meson
Authors:
Marzieh Bahmani,
Alessandro Guida,
Maral Khandan,
Heiko Markus Lacker,
Anupama Reghunath
Abstract:
The precise reconstruction of the mass peak of long-lived heavy neutral leptons (HNLs) helps to improve the sensitivity for sterile neutrino searches in both fixed-target and collider environments (e.g., SHiP and the LHC). We present an analytical framework for reconstructing the HNL mass peak in the semileptonic HNL decay channel \(N\rightarrow lρ\) with \(ρ\toππ^0\), using only the lepton and th…
▽ More
The precise reconstruction of the mass peak of long-lived heavy neutral leptons (HNLs) helps to improve the sensitivity for sterile neutrino searches in both fixed-target and collider environments (e.g., SHiP and the LHC). We present an analytical framework for reconstructing the HNL mass peak in the semileptonic HNL decay channel \(N\rightarrow lρ\) with \(ρ\toππ^0\), using only the lepton and the charged pion emerging from the decay vertex together with kinematic constraints and the known particle masses. Incorporating mass constraints from intermediate resonances (e.g., the \(ρ\) meson) or the parent particle (e.g., the \(W\) boson at the collider experiments), we propose two methods, suitable for experiments with displaced vertex tracking capabilities. The particle-level simulation's results demonstrate that the \(ρ\)-mass constraint method yields promising HNL mass resolution in both beam-dump and collider-based environments. The W-mass constraint method, limited to the HNLs produced via \(W\)-boson decays at the collider-based experiments, shows better HNL mass resolution than the \(ρ\)-mass constraint method.
△ Less
Submitted 1 December, 2025; v1 submitted 1 September, 2025;
originally announced September 2025.
-
A technique to study the elastic and inelastic interaction of quarkonium with hadrons using femtoscopic correlations
Authors:
Marzieh Bahmani,
Daniel Kikoła,
Leszek Kosarzewski
Abstract:
We present a method for the measurement of parameters of elastic and inelastic interactions of charmonium with hadrons. In this technique, we use femtoscopic analysis of charmonium-hadron correlations at low relative momentum and the Lednicky-Lyuboshitz analytical model to extract the interaction parameters. We argue that such a study is already feasible in the LHCb experiment at the LHC, and we d…
▽ More
We present a method for the measurement of parameters of elastic and inelastic interactions of charmonium with hadrons. In this technique, we use femtoscopic analysis of charmonium-hadron correlations at low relative momentum and the Lednicky-Lyuboshitz analytical model to extract the interaction parameters. We argue that such a study is already feasible in the LHCb experiment at the LHC, and we discuss the prospects for studies in the STAR at RHIC and other experiments at the LHC.
△ Less
Submitted 21 December, 2020;
originally announced December 2020.
-
Production of tau tau jj final states at the LHC and the TauSpinner algorithm: the spin-2 case
Authors:
M. Bahmani,
J. Kalinowski,
W. Kotlarski,
E. Richter-Was,
Z. Was
Abstract:
The TauSpinner algorithm is a tool that allows to modify the physics model of the Monte Carlo generated samples due to the changed assumptions of event production dynamics, but without the need of re-generating events. With the help of weights $τ$-lepton production or decay processes can be modified accordingly to a new physics model. In a recent paper a new version TauSpinner ver.2.0.0 has been p…
▽ More
The TauSpinner algorithm is a tool that allows to modify the physics model of the Monte Carlo generated samples due to the changed assumptions of event production dynamics, but without the need of re-generating events. With the help of weights $τ$-lepton production or decay processes can be modified accordingly to a new physics model. In a recent paper a new version TauSpinner ver.2.0.0 has been presented which includes a provision for introducing non-standard states and couplings and study their effects in the vector-boson-fusion processes by exploiting the spin correlations of $τ$-lepton pair decay products in processes where final states include also two hard jets. In the present paper we document how this can be achieved taking as an example the non-standard spin-2 state that couples to Standard Model particles and tree-level matrix elements with complete helicity information included for the parton-parton scattering amplitudes into a $τ$-lepton pair and two outgoing partons. This implementation is prepared as the external (user provided) routine for the TauSpinner algorithm. It exploits amplitudes generated by MadGraph5 and adopted to the TauSpinner algorithm format. Consistency tests of the implemented matrix elements, reweighting algorithm and numerical results for observables sensitive to $τ$ polarization are presented.
△ Less
Submitted 15 January, 2018; v1 submitted 11 August, 2017;
originally announced August 2017.