161 research outputs found
Do Proton-Proton collisions at the LHC energies produce Droplets of Quark-Gluon Plasma?
The proton-proton () collisions at the Large Hadron Collider (LHC), CERN,
Switzerland has brought up new challenges and opportunities in understanding
the experimental findings in contrast to the conventional lower energy
collisions. Usually collisions are used as the baseline measurement at the
GeV and TeV energies in order to understand a possible high density QCD medium
formation in heavy-ion collisions. However, the TeV collisions have
created a new domain of research, where scientists have started observing
heavy-ion-like features (signatures) in high-multiplicity collisions. This
warrants a relook into TeV collisions, if at all QGP-droplets are produced
in such collisions. In this presentation, I discuss some of the new findings
and concepts emerging out in collisions at the LHC energies along with
some of the new emergent phenomena in particle production.Comment: 5 pages, 4-captioned figures, Presented in the plenary session of
Workshop on Frontiers in High Energy Physics (FHEP-2019), Hyderabad, India
(To appear in Springer Proc.
QCD thermodynamics with dynamical overlap fermions
We study QCD thermodynamics using two flavors of dynamical overlap fermions
with quark masses corresponding to a pion mass of 350 MeV. We determine several
observables on N_t=6 and 8 lattices. All our runs are performed with fixed
global topology. Our results are compared with staggered ones and a nice
agreement is found.Comment: 14 pages, 6 figures, 1 tabl
Numerical study of hot strongly interacting matter
I review recent progress in study of strongly interacting matter at high
temperatures using Monte-Carlo simulations in lattice QCD.Comment: Talk presented at Conference on Computational Physics, Oct. 30 - Nov.
3, 2011, Gatlinburg TN, LaTeX uses jpconf11.clo, jpconf.cl
Hadronic vacuum polarization contribution to the anomalous magnetic moments of leptons from first principles
We compute the leading, strong-interaction contribution to the anomalous
magnetic moment of the electron, muon and tau using lattice quantum
chromodynamics (QCD) simulations. Calculations include the effects of , ,
and quarks and are performed directly at the physical values of the
quark masses and in volumes of linear extent larger than . All
connected and disconnected Wick contractions are calculated. Continuum limits
are carried out using six lattice spacings. We obtain
,
and
, where the first error
is statistical and the second is systematic.Comment: 17 pages, 8 figures (in 13 PDF files), RevTeX 4.1. Minor changes to
results and to text. References updated. Matches version published in
Physical Review Letter
QCD thermodynamics with continuum extrapolated dynamical overlap fermions
We study the finite temperature transition in QCD with two flavors of dynamical fermions at a pseudoscalar pion mass of about 350 MeV. We use lattices with temporal extent of =8, 10 and 12. For the first time in the literature a continuum limit is carried out for several observables with dynamical overlap fermions. These findings are compared with results obtained within the staggered fermion formalism at the same pion masses and extrapolated to the continuum limit. The presented results correspond to fixed topology and its effect is studied in the staggered case. Nice agreement is found between the overlap and staggered results
Compact Stars - How Exotic Can They Be?
Strong interaction physics under extreme conditions of high temperature
and/or density is of central interest in modern nuclear physics for
experimentalists and theorists alike. In order to investigate such systems,
model approaches that include hadrons and quarks in a unified approach, will be
discussed. Special attention will be given to high-density matter as it occurs
in neutron stars. Given the current observational limits for neutron star
masses, the properties of hyperonic and hybrid stars will be determined. In
this context especially the question of the extent, to which exotic particles
like hyperons and quarks affect star masses, will be discussed.Comment: Contributon to conference "Nuclear Physics: Present and Future", held
in Boppard (Germany), May 201
Scalar density fluctuation at critical end point in NJL model
Soft mode near the critical end point in the phase diagram of two-flavor
Nambu--Jona-Lasinio (NJL) model is investigated within the leading 1/N_c
approximation with N_c being the number of the colors. It is explicitly shown
by studying the spectral function of the scalar channel that the relevant soft
mode is the scalar density fluctuation, which is coupled with the quark number
density, while the sigma meson mode stays massive.Comment: 9 pages, 4 figure
The QCD equation of state from the lattice
The equation of state of QCD at finite temperatures and baryon densities has
a wide range of applications in many fields of modern particle and nuclear
physics. It is the main ingredient to describe the dynamics of experimental
heavy ion collisions, the expansion of the early universe in the standard model
era and the interior of compact stars. On most scales of interest, QCD is
strongly coupled and not amenable to perturbative investigations. Over the last
decade, first principles calculations using lattice QCD have reached maturity,
in the sense that for particular discretisation schemes simulations at the
physical point have become possible, finite temperature results near the
continuum limit are available and systematic errors begin to be controlled.
This review summarises the current theoretical and numerical state of the art
based on staggered and Wilson fermions.Comment: 72 pages, 36 figures, typos corrected, summary table added; version
published by Prog.Part.Nucl.Phy
Entropy Creation in Relativistic Heavy Ion Collisions
We review current ideas on entropy production during the different stages of
a relativistic nuclear collision. This includes recent results on decoherence
entropy and the entropy produced during the hydrodynamic phase by viscous
effects. We start by a discussion of decoherence caused by gluon bremsstrahlung
in the very first interactions of gluons from the colliding nuclei. We then
present a general framework, based on the Husimi distribution function, for the
calculation of entropy growth in quantum field theories, which is applicable to
the early ("glasma") phase of the collision during which most of the entropy is
generated. The entropy calculated from the Husimi distribution exhibits linear
growth when the quantum field contains unstable modes and the growth rateis
asymptotically equal to the Kolmogorov-Sina\"i (KS) entropy. We outline how the
approach can be used to investigate the problem of entropy production in a
relativistic heavy-ion reaction from first principles. Finally we discuss some
recent results on entropy production in the strong coupling limit, as obtained
from AdS/CFT duality.Comment: 34 pages, 14 figure
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