J. B. Singh

Study of the formation of fragments with different clusterization methods

We present a comparison of different clusterization methods based on simple spatial correlation, spatial-momentum correlation and energy minimization (simulated annealing) by simulating the reactions of O + Ag/Br within the quantum molecular dynamics model. We find that the response of different clusterization algorithms depends on the asymmetry of the reaction. The momentum correlation methods recognize the fragments between 60-100 fm c-1, whereas the simple spatial-correlation method needs a much longer time. The response of a larger nucleon-nucleon cross section as well as of momentum-dependent interaction depends on the clusterization algorithm one is using. It is maximal with the spatial correlation method, whereas it is minimal with the energy minimization method. Interestingly, in the presence of a larger nucleon-nucleon cross section, the momentum cut and energy minimization methods yield a similar evolution. This is true at higher incident energies where the frequency of nucleon-nucleon collisions is very large.

New observables for multiple-parton interactions measurements usingZ+jetsprocesses at the LHC

Multiple-parton interactions play a vital role in hadron-hadron collisions. This paper presents a study of the multiple-parton interactions with simulated Z + jets events in proton-proton collisions at a centre-of-mass energy of 13 TeV. The events are simulated with POWHEG followed by hadronization and parton-showering using PYTHIA 8. The events with dimuon invariant mass in the range of 60--120 GeV are selected for the analysis. The charged particle jets, having minimum transverse momentum of 5 GeV and absolute pseudo-rapidity less than 2, are used to construct the observables for measurements of the multiple-parton interactions. The proposed observables and phase-space region presented in this paper found to have enhanced sensitivity to multiple-parton interactions. The increased sensitivity to MPI will be lead to precise constraints on the parameters of the MPI models.

Study of the Double Parton Scattering via W + 2-Jet Process Using the CMS Detector at LHC

Two hard parton-parton interactions in a single proton-proton (pp) collison lead to double parton scattering (DPS). We investigate DPS in pp collisions at \(\sqrt{s}\) = 7 TeV where the final state includes a W boson, which decays into a muon and a neutrino, and two jets. Various observables sensitive to double parton scattering are investigated after being corrected for detector effects and selection efficiencies. The fraction of W + 2-jet events due to double parton scattering as well as the effective transverse area (\(\sigma _\mathrm{eff}\)) of the hard partonic interaction in the pp collision has been measured with the CMS experiment, using data collected at 7 TeV of center-of-mas energy corresponding to an integrated luminosity of 5 \(\mathrm fb^{-1}\). Studies for the invariance of \(\sigma _\mathrm{eff}\) with centre-of-mass energy, scale and different processes will also be presented in this talk, which are performed using the simulated events from Monte Carlo Event generator PYTHIA8.

Double Parton Scattering Studies via Di-boson Processes Using the CMS Detector at LHC

In high energy proton-proton (pp) collisions at LHC, due to the composite nature of protons, it is possible to have two or more distinct hard parton-parton interactions occuring simultaneously in a single pp collision.

Assembly and characterization of gaseous particle detector: Resistive plate chambers

Charged particles are produced in huge amount in high energy and astro-particle physics experiments such as LHC experiments at CERN, Geneva and in proposed India Based Neutrino Observatory (INO). The identification and measurement of these charged particle set the physics achievable for these experiments. Resistive plate chambers (RPCs), the gaseous detectors which work on the principle of ionization produced in the gaseous medium by fast moving charged particles, are extensively used in detection of charged particles. A laboratory is set-up at Department of Physics, Panjab University for the fabrication and testing of RPC detectors. This paper present the assembly and characterization performance of the fabricated RPCs.

Multi-fragmentation in heavy-ion collisions: Role of system-size effects, cross-section and equation of state

Within the quantum molecular dynamics model, we study the role of different equations of state and their momentum dependence as well as different nucleon-nucleon cross-sections in multi-fragmentation. We find that the significance of momentum dependent interactions depends on the asymmetry of the reaction. The role of larger cross-section reduces to marginal if momentum dependence is included in the interaction. We also present the system-size effects in multi-fragmentation and shall show that the multiplicity of any kind of fragment exhibits a power law behaviour.