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P. Shukla

Publications and source records attributed to P. Shukla.

At least 19 recordsLinked to original sources
arXiv2025

GReX: An Instrument Overview and New Upper Limits on the Galactic FRB Population

We present the instrument design and initial results for the Galactic Radio Explorer (GReX), an all-sky monitor for exceptionally bright transients in the radio sky. This instrument builds on the success of STARE2 to search for fast radio bursts (FRBs) from the Milky Way and its satellites. This instrument has deployments across the globe, with wide sky coverage and searching down to $32\,\mu\text{s}$ time resolution, enabling the discovery of new super giant pulses. Presented here are the details of the hardware and software design of the instrument, performance in sensitivity and other key metrics, and experience in building a global-scale, low-cost experiment. We follow this discussion with experimental results on validation of the sensitivity via hydrogen-line measurements. We then update the rate of Galactic FRBs based on non-detection in the time since FRB 200428. Our results suggest FRB-like events are even rarer than initially implied by the detection of a MJy burst from SGR J1935+2154 in April 2020.

astro-ph.HE↗
arXiv2024

Charge ratio of cosmic ray muons in momentum range ~ 1 to 3 GeV/c

This work presents the measurements of the cosmic muon charge ratio as a function of full azimuthal angle and momentum within the range of 0.8 to 3.0 GeV/c, using the mini-ICAL detector. The detector, comprising 10 layers of RPCs, has collected cosmic muon data since August 2018 till recent time, at an altitude of 160 m above sea level at the Inter-Institutional Center for High Energy Physics in Madurai, India $(9^\circ56'\,N, 78^\circ00'\,E)$. The muon charge identification is achieved through the use of a magnetic field of strength 1.4 T. The analysis shows that the cosmic muon charge ratio, $R_\mu = N_{\mu^+}/N_{\mu^-}$, ranges from 1.1 to 1.2 and has small dependency on the zenith angle. The charge ratio's dependence on momentum and azimuthal angle is thoroughly examined for a wide range of zenith angle upto $50^\circ$. These measurements are compared with the predictions from various combinations of different hadronic models in CORSIKA extensive air shower simulations.

hep-ex↗
arXiv2017

The Contours of Crowd Capability

In this work we use the theory of Crowd Capital as a lens to compare and contrast a number of IS tools currently in use by organizations for crowd-engagement purposes. In doing so, we contribute to both the practitioner and research domains. For the practitioner community we provide decision-makers with a convenient and useful resource, in table-form, outlining in detail some of the differing potentialities of crowd-engaging IS. For the research community we begin to unpack some of the key properties of crowd-engaging IS, including some of the differing qualities of the crowds that these IS application engage.

cs.CY↗
arXiv2017

A Geography of Participation in IT-Mediated Crowds

In this work we seek to understand how differences in location affect participation outcomes in IT-mediated crowds. To do so, we operationalize Crowd Capital Theory with data from a popular international creative crowdsourcing site, to determine whether regional differences exist in crowdsourcing participation outcomes. We present the early results of our investigation from data encompassing 1,858,202 observations from 28,214 crowd members on 94 different projects in 2012. Using probit regressions to isolate geographic effects by continental region, we find significant variation across regions in crowdsourcing participation. In doing so, we contribute to the literature by illustrating that geography matters in respect to crowd participation. Further, our work illustrates an initial validation of Crowd Capital Theory as a useful theoretical model to guide empirical inquiry in the fast-growing domain of IT-mediated crowds.

cs.CY↗
arXiv2017

Crowd Capital in Governance Contexts

To begin to understand the implications of the implementation of IT-mediated Crowds for Politics and Policy purposes, this research builds the first-known dataset of IT-mediated Crowd applications currently in use in the governance context. Using Crowd Capital theory and governance theory as frameworks to organize our data collection, we undertake an exploratory data analysis of some fundamental factors defining this emerging field. Specific factors outlined and discussed include the type of actors implementing IT-mediated Crowds in the governance context, the global geographic distribution of the applications, and the nature of the Crowd-derived resources being generated for governance purposes. The findings from our dataset of 209 on-going endeavours indicates that a wide-diversity of actors are engaging IT-mediated Crowds in the governance context, both jointly and severally, that these endeavours can be found to exist on all continents, and that said actors are generating Crowd-derived resources in at least ten distinct governance sectors. We discuss the ramifications of these and our other findings in comparison to the research literature on the private-sector use of IT-mediated Crowds, while highlighting some unique future research opportunities stemming from our work.

cs.CY↗
arXiv2014

Pion $p_T$ spectra in $p+p$ collisions as a function of $\sqrt{s}$ and event multiplicity

We study the charged pion transverse momentum ($p_T$) spectra in $p$+$p$ collisions as a function of collision energy $\sqrt{s}$ and event multiplicity using Tsallis distribution. This study gives an insight of the pion production process in $p+p$ collisions. The study covers pion spectra measured in $p+p$ collisions at SPS energies (6.27-17.27 GeV), RHIC energies (62.4 GeV and 200 GeV) and LHC energies (900 GeV, 2.76 TeV and 7 TeV). The Tsallis parameters have been obtained and parameterized as a function of $\sqrt{s}$. The study suggests that as we move to higher energy more and more hard processes contribute to the spectra. We also study the charged pion spectra for different event multiplicities in $p$+$p$ collisions for LHC energies using Tsallis distribution. The variation of the Tsallis parameters as a function of event multiplicity has been obtained and their behavior is found to be independent of collision energy.

hep-ph↗
arXiv2014

Overview of quarkonia and heavy flavour measurements by CMS

This writeup summarizes recent CMS results on quarkonia measurements in pp, pPb and PbPb collisions at LHC. The excellent muon detection capability of CMS allows measurement of charmonia states at high transverse momentum ($p_T$) while the $Υ$ states can be reconstructed starting at zero $p_T$. The absolute and relative yields of different charmonia and bottomonia states modified in PbPb collisions (over pp collisions) are described. The vertexing capability of CMS enables measurement of B meson energy loss via its decay to J/$ψ$. An overview of these measurements is given. How these measurements compare with other experiments at RHIC and LHC and have improved the understanding of heavy ion collisions has been discussed.

nucl-ex↗
arXiv2013

System size dependence of hadron $p_T$ spectra in p+p and Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV

We make a systematic study of transverse momentum ($p_T$) spectra of hadrons produced in $p+p$ and in different centralities of Au+Au collisions at $\sqrt{s}=200$\,GeV using phenomenological fit functions. The Tsallis distribution gives a very good description of hadron spectra in $p+p$ collisions with just two parameters but does not produce the same in Au+Au collisions at intermediate $p_{T}$. To explain the hadron spectra in heavy ion collisions in a wider $p_{T}$ range we propose a modified Tsallis function by introducing an additional parameter which accounts for collective flow. The new analytical function gives a very good description of both mesons and baryons spectra at all centralities of Au+Au collisions in terms of parameters having a potential physics interpretation. With this modified Tsallis function we study the spectra of pions, kaons, protons, $Λ(1115)$ and $Ξ^{-}$ as a function of system size at $\sqrt{s_{NN}}$ = 200 GeV. The parameter representing transverse flow increases with system size and is found to be more far baryons than that for mesons in central Au+Au collisions. The freeze-out temperature for baryons increases with centrality in Au+Au collisions more rapidly than for mesons.

nucl-th↗
arXiv2013

Hadron spectra in p+p collisions at RHIC and LHC energies

We present the systematic analysis of transverse momentum ($p_T$) spectra of identified hadrons in p+p collisions at RHIC ($\sqrt{s}$ = 62.4 and 200 GeV) and at LHC energies ($\sqrt{s}$ = 0.9, 2.76 and 7.0 TeV) using phenomenological fit functions. We review various forms of Hagedorn and Tsallis distributions and show their equivalence. We use Tsallis distribution which successfully describes the spectra in p+p collisions using two parameters, Tsallis temperature $T$ which governs the soft bulk spectra and power $n$ which determines the initial production in partonic collisions. We obtain these parameters for pions, kaons and protons as a function of center of mass energy ($\sqrt{s}$). It is found that the parameter $T$ has a weak but decreasing trend with increasing $\sqrt{s}$. The parameter $n$ decreases with increasing $\sqrt{s}$ which shows that production of hadrons at higher energies are increasingly dominated by point like qq scatterings. Another important observation is with increasing $\sqrt{s}$, the separation between the powers for protons and pions narrows down hinting that the baryons and mesons are governed by same production process as one moves to the highest LHC energy.

hep-ph↗
arXiv2012

Components of the dilepton continuum in Pb+Pb collisions at $\sqrt{s_{_{NN}}} = 2.76 $ TeV

The dilepton invariant mass spectrum measured in heavy-ion collisions includes contributions from important QGP probes such as thermal radiation and the quarkonium ($J/ψ$, $ψ'$ and $Υ$) states. Dileptons coming from hard $q \bar q$ scattering, the Drell-Yan process, contribute in all mass regions. In heavy-ion colliders, such as the LHC, semileptonic decays of heavy flavor hadrons provide a substantial contribution to the dilepton continuum. The dilepton continuum can give quantitative information about heavy quark yields and their modification in the medium and thus it is important to know all different sources which populate the continuum. In the present study, we calculate $c \bar c$ and $b \bar b$ production and determine their contributions to the dilepton continuum in Pb+Pb collisions at $\sqrt{s_{_{NN}}} = 2.76$ TeV with and without including heavy quark energy loss. We also calculate the rates for Drell-Yan and thermal dilepton production. The contributions to the continuum from these dilepton sources are studied in the kinematic ranges relevant for the LHC detectors. The relatively high $p_T$ cutoff for single leptons excludes most dileptons produced by the thermal medium. Heavy flavors are the dominant source of dilepton production in all the kinematic regimes except at forward rapidities where Drell-Yan start dominating in high mass range beyond 10 GeV/$c^2$.

hep-ph↗
arXiv2012

Transverse mass spectra and scaling of hadrons at RHIC and LHC energies

We present a systematic study of transverse mass spectra ($m_T$) of mesons and baryons at RHIC and LHC energies. In an earlier study, it was shown that all the mesons produced in p+p and d+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV follow $m_T$ scaling while in Au+Au collisions at same energy the mesons with strange and charm quark contents do not follow $m_T$ scaling which can be attributed to medium modifications. We extend this study for baryons produced in all above colliding systems at $\sqrt{s_{NN}}$ = 200 GeV. Although all available baryon spectra behave differently from mesons but are found to scale with protons for both p+p and d+Au collisions. In case of Au+Au collisions, the strange baryons behave differently from protons. This study has also been performed on the meson spectra in p+p collisions at 62.4 GeV which lies in between the highest RHIC energy and SPS energy where the $m_T$ scaling was first observed and we arrive at same conclusions as those at 200 GeV. We test the $m_T$ scaling at LHC with the first meson spectra measured in p+p collisions at 900 GeV and find that the $m_T$ spectra of kaons and $ϕ$ do not scale with pions. Thus $m_T$ scaling which was working well up to p+p collisions at 200 GeV seems to be broken. Here we use all data measured in the mid rapidity region. Baryon to meson ratio is studied as a function of $m_T$, at different energies and for different systems and is found that this ratio for p+p at 900 GeV is quite different from that in p+p collisions at RHIC energies.

hep-ph↗
arXiv2011

Meson spectra and m_T scaling in p+p, d+Au and Au+Au collisions at \sqrtS_NN=200 GeV

The meson spectra provide insight into the particle production mechanism and interaction in the hadronic and quark gluon plasma (QGP) phases. The detailed study of systematics of meson spectra is important also because it acts as ingredient for estimating the hadronic decay backgrounds in the photon, single lepton and dilepton spectra which are the penetrating probes of quark gluon plasma. In this work, we parameterize experimentally measured pion spectra and then obtain the spectra of other light mesons using a property known as $m_T$ scaling. The $m_{T}$ scaled spectra for each meson is compared with experimental data for p+p, d+Au and Au+Au systems at $\surd s_{NN} $ = 200 GeV. The agreement of the $m_{T}$ scaled and experimental data shapes are excellent in most cases and their fitted relative normalization gives ratio of meson to pion $m_T$ spectra. These ratios are useful to obtain the hadronic decay contribution in photonic and leptonic channels but also point to the quantitative changes in the dynamics of the heavy ion collision over p+p collisions. It is shown that, the particles with charm contents behave differently as compared to pions in d+Au systems and particles either with strange or charm contents behave differently from pions in Au+Au systems. For Au+Au system, three centrality classes have been studied which reveal that for the particles like kaon and $ϕ$, peripheral collision data is better reproduced as compared to central and their relative ratios with pions also increase as the collisions become more central.

hep-ph↗
arXiv2008

Dynamics of k-core percolation

In many network applications nodes are stable provided they have at least k neighbors, and a network of k-stable nodes is called a k-core. The vulnerability to random attack is characterized by the size of culling avalanches which occur after a randomly chosen k-core node is removed. Simulations of lattices in two, three and four dimensions, as well as small world networks, indicate that power-law avalanches occur in first order k-core systems, while truncated avalanches are characteristic of second order cases.

cond-mat.stat-mech↗
arXiv2007

A large acceptance scintillator detector with wavelength shifting fibre read-out for search of eta-nucleus bound states

A large acceptance scintillator detector with wavelength shifting optical fibre readout has been designed and built to detect the decay particles of $η$-nucleus bound system (the so-called $η$-mesic nuclei), namely, protons and pions. The detector, named as ENSTAR detector, consists of 122 pieces of plastic scintillator of various shapes and sizes, which are arranged in a cylindrical geometry to provide particle identification, energy loss and coarse position information for these particles. A solid angle coverage of $\sim$95% of total 4$π$ is obtained in the present design of the detector. Monte Carlo phase space calculations performed to simulate the formation and decay of $η$-mesic nuclei suggest that its decay particles, the protons and pions are emitted with an opening angle of 150$^\circ \pm 20^\circ$, and with energies in the range of 25 to 300 MeV and 225 to 450 MeV respectively. The detailed GEANT simulations show that $\sim$ 80 % of the decay particles (protons and pions) can be detected within ENSTAR. Several test measurements using alpha source, cosmic-ray muons etc. have been carried out to study the response of ENSTAR scintillator pieces. The in-beam tests of fully assembled detector with proton beam of momentum 870 MeV/c from the Cooler synchrotron COSY have been performed. The test results show that the scintillator fiber design chosen for the detector has performed satisfactorily well. The present article describes the detector design, simulation studies, construction details and test results.

physics.ins-det↗
arXiv2006

Standard monomial bases, moduli of vector bundles, and invariant theory

Consider the diagonal action of the special orthogonal group on the direct sum of a finite number of copies of the standard representation--the underlying field is assumed to be algebraically closed and of characteristic not equal to two. We construct a "standard monomial" basis for the ring of polynomial invariants for this action. We then deduce, by a deformation argument, our main result that this ring of polynomial invariants is Cohen-Macaulay. We give three applications of this result: (1) the first and second fundamental theorems of invariant theory for the above action; (2) Cohen-Macaulayness of the moduli space of equivalence classes of semi-stable vector bundles of rank two and degree zero on a smooth projective curve of genus at least three (for this application, characteristic three is also excluded); (3) a basis in terms of traces for the ring of polynomial invariants for the diagonal adjoint action of the special linear group SL(2) on a finite number of copies of its Lie algebra sl(2).

math.AG↗
arXiv2005

Standard monomial bases and geometric consequences for certain rings of invariants

Consider the diagonal action of $SL_n(K)$ on the affine space $X=V^{\oplus m}\oplus (V^*)^{\oplus q}$ where $V=K^n, K$ an algebraically closed field of arbitrary characteristic and $m,q>n$. We construct a "standard monomial" basis for the ring of invariants $K[X]^{SL_n(K)}$. As a consequence, we deduce that $K[X]^{SL_n(K)}$ is Cohen-Macaulay. We also present the first and second fundamental theorems for $SL_n(K)$-actions.

math.AG↗
arXiv2002

A quasiparticle description of the equation of state in SU(3) lattice QCD

The lattice data for $N_f=2$ and $N_f=3$ based on staggered fermion formulations have been parameterized using a phenomenological equation of state for noninteracting but massive quasiparticles. Such a model would be a preferable starting point for phenomenological hadronization models and for a description of the strongly interacting matter near the phase transition.

hep-ph↗