558 research outputs found
Thermal Model Description of p--Pb Collisions at = 5.02 TeV
The ALICE data on light flavor hadron production obtained in
collisions at = 5.02 TeV are studied in the thermal model
using the canonical approach with exact strangeness conservation. The chemical
freeze-out temperature is independent of centrality except for the lowest
multiplicity bin, with values close to 160 MeV but consistent with those
obtained in collisions at = 2.76 TeV. The value of the
strangeness non-equilibrium factor is slowly increasing with
multiplicity from 0.9 to 0.96, i.e. it is always very close to full chemical
equilibrium.Comment: 10 pages, 12 figure
Equation of State of Hadronic matter and Electromagnetic Radiation from Relativisitic Heavy Ion Collisions
We study the radiation of thermal photons and dileptons likely to be produced
in relativistic heavy ion collisions. We find that the thermal photon
multiplicity scales with the charged pion multiplicity as
with for a transversely expanding system, contrary to the
general belief of a quadratic dependence. The scaling is shown to be valid,
both for real and virtual photons. The coefficient of proportionality at a
given energy may help us identify the appropriate equation of state of hot
hadronic matter produced in such collisions.Comment: 3 pages, RevTeX, three figures in postscrip
Multiplicity Dependence of Non-extensive Parameters for Strange and Multi-Strange Particles in Proton-Proton Collisions at TeV at the LHC
The transverse momentum () spectra in proton-proton collisions at
= 7 TeV, measured by the ALICE experiment at the LHC are analyzed
with a thermodynamically consistent Tsallis distribution. The information about
the freeze-out surface in terms of freeze-out volume, temperature and the
non-extenisivity parameter, , for , ,
and are extracted by
fitting the spectra with Tsallis distribution function. The
freeze-out parameters of these particles are studied as a function of charged
particle multiplicity density (). In addition, we also study
these parameters as a function of particle mass to see any possible mass
ordering. The strange and multi-strange particles show mass ordering in volume,
temperature, non-extensive parameter and also a strong dependence on
multiplicity classes. It is observed that with increase in particle
multiplicity, the non-extensivity parameter, decreases, which indicates the
tendency of the produced system towards thermodynamic equilibration. The
increase in strange particle multiplicity is observed to be due to the increase
of temperature and not to the size of the freeze-out volume.Comment: Version similar to the published version in EPJ
Hadronic Ratios and the Number of Projectile Participants. Thermal hadron production in Si-Au collisions
We investigate the dependence of hadronic ratios on the number of projectile
participants using a thermal model incorporating exact baryon number and
strangeness conservation. A comparison is made with results from
collisions obtained at the BNL-AGS.Comment: 5 pages LaTeX2e, 4 figures in Postscript forma
Radial Flow in Non-Extensive Thermodynamics and Study of Particle Spectra at LHC in the Limit of Small
We expand the Tsallis distribution in a Taylor series of powers of (q-1),
where q is the Tsallis parameter, assuming q is very close to 1. This helps in
studying the degree of deviation of transverse momentum spectra and other
thermodynamic quantities from a thermalized Boltzmann distribution. After
checking thermodynamic consistency, we provide analytical results for the
Tsallis distribution in the presence of collective flow up to the first order
of (q-1). The formulae are compared with the experimental data.Comment: Replaced with Accepted version in Eur. Phys. J.
Radial Flow and Differential Freeze-out in Proton-Proton Collisions at TeV at the LHC
We analyse the transverse momentum ()-spectra as a function of
charged-particle multiplicity at midrapidity () for various
identified particles such as , , , ,
, , and + in
proton-proton collisions at = 7 TeV using Boltzmann-Gibbs Blast Wave
(BGBW) model and thermodynamically consistent Tsallis distribution function. We
obtain the multiplicity dependent kinetic freeze-out temperature () and radial flow () of various particles after fitting the -distribution with BGBW model. Here, exhibits mild dependence
on multiplicity class while shows almost independent behaviour. The
information regarding Tsallis temperature and the non-extensivity parameter
() are drawn by fitting the -spectra with Tsallis distribution
function. The extracted parameters of these particles are studied as a function
of charged particle multiplicity density (). In addition to
this, we also study these parameters as a function of particle mass to observe
any possible mass ordering. All the identified hadrons show a mass ordering in
temperature, non-extensive parameter and also a strong dependence on
multiplicity classes, except the lighter particles. It is observed that as the
particle multiplicity increases, the -parameter approaches to
Boltzmann-Gibbs value, hence a conclusion can be drawn that system tends to
thermal equilibrium. The observations are consistent with a differential
freeze-out scenario of the produced particles.Comment: Published versio
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