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M. Kaur

Publications and source records attributed to M. Kaur.

33 records · Page 2Linked to original sources
arXiv2018

Multiplicity spectra in pp collisions at LHC energies in terms of Gamma and Tsallis distributions

In recent years the Tsallis statistics is gaining popularity in describing charged particle produc- tion and their properties, in particular pT spectra and the multiplicities in high energy particle collisions. Motivated by its success, an analysis of the LHC data of proton-proton collisions at ener- gies ranging from 0.9 TeV to 7 TeV in different rapidity windows for charged particle multiplicities has been done. A comparative analysis is performed in terms of the Tsallis distribution, the Gamma distribution and the shifted-Gamma distribution. An interesting observation on the inapplicability of these distributions at sqrt{s}=7 TeV in the lower rapidity windows is intriguing. The non-extensive nature of the Tsallis statistics is studied by determining the entropic index and its energy depen- dence. The analysis is extrapolated to predict the multiplicity distribution at sqrt{s}=14 TeV for one rapidity window, |y| < 1.5 with the Tsallis function.

hep-ph↗
arXiv2018

Magnetothermodynamics: Measurements of the thermodynamic properties in a relaxed magnetohydrodynamic plasma

We have explored the thermodynamics of compressed magnetized plasmas in laboratory experiments and we call these studies "magnetothermodynamics". The experiments are carried out in the Swarthmore Spheromak eXperiment device. In this device, a magnetized plasma source is located at one end and at the other end, a closed conducting can is installed. We generate parcels of magnetized plasma and observe their compression against the end wall of the conducting cylinder. The plasma parameters such as plasma density, temperature, and magnetic field are measured during compression using HeNe laser interferometry, ion Doppler spectroscopy and a linear $\dot{B}$ probe array, respectively. To identify the instances of ion heating during compression, a PV diagram is constructed using measured density, temperature, and a proxy for the volume of the magnetized plasma. Different equations of state are analyzed to evaluate the adiabatic nature of the compressed plasma. A 3D resistive magnetohydrodynamic code (NIMROD) is employed to simulate the twisted Taylor states and show stagnation against the end wall of the closed conducting can. The simulation results are consistent to what we observe in our experiments.

physics.plasm-ph↗
arXiv2018

Magnetothermodynamics: Measuring equations of state in a relaxed magnetohydrodynamic plasma

We report the first measurements of equations of state of a fully relaxed magnetohydrodynamic (MHD) laboratory plasma. Parcels of magnetized plasma, called Taylor states, are formed in a coaxial magnetized plasma gun, and are allowed to relax and drift into a closed flux conserving volume. Density, ion temperature, and magnetic field are measured as a function of time as the Taylor states compress and heat. The theoretically predicted MHD and double adiabatic equations of state are compared to experimental measurements. We find that the MHD equation of state is inconsistent with our data.

physics.plasm-ph↗
arXiv2017

Modified Weibull and Tsallis Distributions for multiplicities in $e^{+}e^{-}$ collisions at LEP2 energies

Multiplicity distributions of charged particles produced in the $e^{+}e^{-}$ collisions at LEP2 energies ranging from 91 to 206 GeV in full phase space, are compared with predictions from Tsallis $q$-statistics and the recently proposed Weibull distribution functions.~The analysis uses data from two LEP experiments, L3 and OPAL.~It is shown that Tsallis $q$-statistics explains the data in a statistically acceptable manner in full phase space at all energies, while the Weibull distribution fails to explain the underlying properties of the data.~Modifications to the distributions proposed earlier, are applied to uncover manifold improvements in explaining the data characteristics.

hep-ph↗
arXiv2017

Modified Tsallis and Weibull distributions for multiplicities in e+e- collisions

Multiplicity distributions of charged particles produced in the e^{+}e^{-} collisions at energies ranging from 14 to 91 GeV are studied using Tsallis q-statistics and the recently proposed Weibull distribution functions, in both restricted rapidity windows as well as in full phase space. It is shown that Tsallis $q$-statistics explains the data excellently in all rapidity ranges while the Weibull distribution fails to reproduce the data in full phase space. Modifications to the distributions are proposed to establish manifold improvements in the fitting of the data.

hep-ph↗
arXiv2016

Measurement of the cross-section ratio sigma_{psi(2S)}/sigma_{J/psi(1S)} in deep inelastic exclusive ep scattering at HERA

The exclusive deep inelastic electroproduction of $ψ(2S)$ and $J/ψ(1S)$ at an $ep$ centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range $2 < Q^2 < 80$ GeV$^2$, $30 < W < 210$ GeV and $|t| < 1$ GeV$^2$, where $Q^2$ is the photon virtuality, $W$ is the photon-proton centre-of-mass energy and $t$ is the squared four-momentum transfer at the proton vertex. The data for $2 < Q^2 < 5$ GeV$^2$ were taken in the HERA I running period and correspond to an integrated luminosity of 114 pb$^{-1}$. The data for $5 < Q^2 < 80$ GeV$^2$ are from both HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb$^{-1}$. The decay modes analysed were $μ^+μ^-$ and $J/ψ(1S) π^+π^-$ for the $ψ(2S)$ and $μ^+μ^-$ for the $J/ψ(1S)$. The cross-section ratio $σ_{ψ(2S)}/σ_{J/ψ(1S)}$ has been measured as a function of $Q^2, W$ and $t$. The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.

hep-ex↗
arXiv2016

Parton level study of high ET jets in hard QCD processes at LHC

Inclusive jet production will dominate the high $Q^{2}$ final states at the LHC.~In this work we try to estimate the up-to-date expectations, for high $E_{T}$ jets and their expected origin from the various parton-parton scattering processes. For these studies we have used a standard Parton Distribution Function (PDF) and simulated millions of events with the PYTHIA8 event genertor. The results are compared with simulations for center-of-mass energies of 0.9 TeV, 2.36 TeV, 7 TeV and 14 TeV corresponding to existing and future LHC runs. We present some expectations for the relative cross sections of different quark flavours which indicates that eventually we might be able to measure the cross section for b-flavoured jets with reasonable accuracy up to an $E_T$ of a few TeV.

hep-ph↗
arXiv2016

Measurement of the cross-section ratio sigma_{psi(2S)}/sigma_{J/psi(1S)} in deep inelastic exclusive ep scattering at HERA

The exclusive deep inelastic electroproduction of $ψ(2S)$ and $J/ψ(1S)$ at an $ep$ centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range $2 < Q^2 < 80$ GeV$^2$, $30 < W < 210$ GeV and $|t| < 1$ GeV$^2$, where $Q^2$ is the photon virtuality, $W$ is the photon-proton centre-of-mass energy and $t$ is the squared four-momentum transfer at the proton vertex. The data for $2 < Q^2 < 5$ GeV$^2$ were taken in the HERA I running period and correspond to an integrated luminosity of 114 pb$^{-1}$. The data for $5 < Q^2 < 80$ GeV$^2$ are from both HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb$^{-1}$. The decay modes analysed were $μ^+μ^-$ and $J/ψ(1S) \,π^+π^-$ for the $ψ(2S)$ and $μ^+μ^-$ for the $J/ψ(1S)$. The cross-section ratio $σ_{ψ(2S)}/σ_{J/ψ(1S)}$ has been measured as a function of $Q^2, W$ and $t$. The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.

hep-ex↗
arXiv2015

Production of exclusive dijets in diffractive deep inelastic scattering at HERA

Production of exclusive dijets in diffractive deep inelastic $e^\pm p$ scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb$^{-1}$. The measurement was performed for $γ^*-p$ centre-of-mass energies in the range $90 < W < 250$ GeV and for photon virtualities $Q^2 > 25$ GeV$^2$. Energy and transverse-energy flows around the jet axis are presented. The cross section is presented as a function of $β$ and $ϕ$, where $β=x/x_{\rm I\!P}$, $x$ is the Bjorken variable and $x_{\rm I\!P}$ is the proton fractional longitudinal momentum loss. The angle $ϕ$ is defined by the $γ^*-$dijet plane and the $γ^*-e^\pm$ plane in the rest frame of the diffractive final state. The $ϕ$ cross section is measured in bins of $β$. The results are compared to predictions from models based on different assumptions about the nature of the diffractive exchange.

hep-ex↗
arXiv2014

Measurement of beauty and charm production in deep inelastic scattering at HERA and measurement of the beauty-quark mass

The production of beauty and charm quarks in ep interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared 5 < Q^2 < 1000 GeV^2 using an integrated luminosity of 354 pb^{-1}. The beauty and charm content in events with at least one jet have been extracted using the invariant mass of charged tracks associated with secondary vertices and the decay-length significance of these vertices. Differential cross sections as a function of Q^2, Bjorken x, jet transverse energy and pseudorapidity were measured and compared with next-to-leading-order QCD calculations. The beauty and charm contributions to the proton structure functions were extracted from the double-differential cross section as a function of x and Q^2. The running beauty-quark mass, m_b at the scale m_b, was determined from a QCD fit at next-to-leading order to HERA data for the first time and found to be 4.07 \pm 0.14 (fit} ^{+0.01}_{-0.07} (mod.) ^{+0.05}_{-0.00} (param.) ^{+0.08}_{-0.05} (theo) GeV.

hep-ex↗
arXiv2014

Further studies of the photoproduction of isolated photons with a jet at HERA

In this extended analysis using the ZEUS detector at HERA, the photoproduction of isolated photons together with a jet is measured for different ranges of the fractional photon energy, $x_γ^{\mathrm{meas}}$, contributing to the photon-jet final state. Cross sections are evaluated in the photon transverse-energy and pseudorapidity ranges $6 < E_T^γ < 15$ GeV and $-0.7 < η^γ < 0.9$, and for jet transverse-energy and pseudorapidity ranges $4 < E_T^{\rm jet} < 35$ GeV and $-1.5 < η^{\rm jet} < 1.8$, for an integrated luminosity of 374 $\mathrm{pb}^{-1}$. The kinematic observables studied comprise the transverse energy and pseudorapidity of the photon and the jet, the azimuthal difference between them, the fraction of proton energy taking part in the interaction, and the difference between the pseudorapidities of the photon and the jet. Higher-order theoretical calculations are compared to the results.

hep-ex↗
arXiv2014

Measurement of D* photoproduction at three different centre-of-mass energies at HERA

The photoproduction of $D^{*\pm}$ mesons has been measured with the ZEUS detector at HERA at three different ep centre-of-mass energies, $\sqrt{s}$, of 318, 251 and 225 GeV. For each data set, $D^*$ mesons were required to have transverse momentum, $p_T^{D^*}$, and pseudorapidity, $η^{D^*}$, in the ranges $1.9 < p_T^{D^*} < 20$ GeV and $|η^{D^*}|<1.6$. The events were required to have a virtuality of the incoming photon, $Q^2$, of less than 1 GeV$^2$. The dependence on $\sqrt{s}$ was studied by normalising to the high-statistics measurement at $\sqrt{s} =318$ GeV. This led to the cancellation of a number of systematic effects both in data and theory. Predictions from next-to-leading-order QCD describe the $\sqrt{s}$ dependence of the data well.

hep-ex↗
arXiv2014

Deep inelastic cross-section measurements at large y with the ZEUS detector at HERA

The reduced cross sections for $e^{+}p$ deep inelastic scattering have been measured with the ZEUS detector at HERA at three different centre-of-mass energies, $318$, $251$ and $225$ GeV. The cross sections, measured double differentially in Bjorken $x$ and the virtuality, $Q^2$, were obtained in the region $0.13\ \leq\ y\ \leq\ 0.75$, where $y$ denotes the inelasticity and $5\ \leq\ Q^2\ \leq\ 110$ GeV$^2$. The proton structure functions $F_2$ and $F_L$ were extracted from the measured cross sections.

hep-ex↗
arXiv2014

Measurement of neutral current e+/-p cross sections at high Bjorken x with the ZEUS detector

The neutral current e+/-p cross section has been measured up to values of Bjorken x of approximately 1 with the ZEUS detector at HERA using an integrated luminosity of 187 inv. pb of e-p and 142 inv. pb of e+p collisions at sqrt(s) = 318GeV. Differential cross sections in x and Q2, the exchanged boson virtuality, are presented for Q2 geq 725GeV2. An improved reconstruction method and greatly increased amount of data allows a finer binning in the high-x region of the neutral current cross section and leads to a measurement with much improved precision compared to a similar earlier analysis. The measurements are compared to Standard Model expectations based on a variety of recent parton distribution functions.

hep-ex↗