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Quark Number Susceptibility in Hard Thermal Loop Approximation
| Content Provider | Semantic Scholar |
|---|---|
| Author | Chakraborty, Purnendu Mustafa, Munshi Golam Thoma, Markus H. |
| Abstract | In recent years substantial experimental and theoretical efforts have been undertaken to investigate the versatile physics issues involved in ultra-relativistic heavy-ion collisions, i.e., collisions of atomic nuclei in which centre-of-mass energy per nucleon is much larger than the nucleon rest mass. The principal goal of this initiative is to explore the phase structure of the underlying theory of strong interactions – Quantum Chromodynamics (QCD) – by creating in the laboratory a new state of matter, the so-called Quark-Gluon Plasma (QGP). This new state of matter is predicted to exist under extreme conditions like at high temperatures and/or densities, when a phase transition takes place from a hadronic to a deconfined state of quarks and gluons [1]. Such information has essentially been confirmed by numerical lattice QCD calculations [2] at finite temperature, which show a rapid increase in energy density and entropy density as a function of temperature. Numerical solutions of QCD also suggest that the critical temperature is about 160 MeV [3] and provide information on the equation of state [4]. The various measurements taken at CERN SPS within the Lead Beam Programme do lead to strong ‘circumstantial evidence’ for the formation of the QGP [5,6]. Evidence is circumstantial as any direct formation of the QGP cannot be identified. Only by some noble indirect diagnostic probes like the suppression of the J/Ψ particle, the enhanced production of strange particles, specially strange antibaryons, excess production of photons and dileptons, the formation of disoriented chiral condensates, etc. the discovery can be achieved. An extensive amount of theoretical study has also been devoted over the last two decades in favour of these well accepted probes of a deconfinement (QGP) phase. Recently screening and fluctuation of conserved quantities have been considered as an important and relevant probes of the QGP formation in heavy-ion collisions [7–10]. In the confined/chirally broken phase charges are associated with the hadrons in integer units whereas in the deconfined/chirally restored phase they are associated with the quarks in fractional units which could lead to charge fluctuations which are different in the two phases [7,10]. The fluctuations can generally be related to the associated susceptibilities [7,11]. The quark number susceptibility is associated with the number fluctuation which measures the response of the number density with infinitesimal change of the quark chemical potential. Hence the quark number susceptibility can be related to charge fluctuations [10] and is therefore of direct experimental relevance. The quark number susceptibility has been investigated in lattice QCD simulation [12] which showed that it is zero at low temperature and rises suddenly to nonzero values across the deconfinement phase transition. At high temperature QCD it has been analysed [13] to show the non-perturbative temperature effects at next-to-leading order. Recently, it has been discussed [14] in connection with the role of the fluctuations during the dense stages of the collision to exploit the electromagnetic probes with the hadronic probes. A very recent lattice simulation [15] has verified a new relation between susceptibilities and screening masses and explain that the nonperturbative phenomena are closely connected with deviations from weak coupling limit or bare perturbation theory and indicate the need to resum the weak coupling series. The purpose of the present calculation is to investigate the quark number susceptibility within the HTL-resummed perturbation theory which incorporates the non-perturbative effects such as effective masses of the collective quark modes (quark and plasmino modes in the medium originating from the poles of the HTL-propagators) and Landau damping for spacelike quark momenta, reflecting the physical picture of the QGP as a gas of quasiparticles. As we will see below, the quark number susceptibility obtained in HTL approximation is in agreement with recent lattice [15] observations. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://cds.cern.ch/record/525348/files/0111022.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Approximation Arabic numeral 0 Cold Temperature Disease susceptibility Fever HYPOTRICHOSIS 6 High Threshold Logic IBM 1401 Symbolic Programming System Integer (number) Interaction Ions Large Lattice QCD Nucleons Numerical analysis Offset binary Perturbation theory (quantum mechanics) Phase Transition Photons Plasma-enhanced chemical vapor deposition Quantum Dots Quantum fluctuation Quasiparticle Relevance Simulation Solutions Zero suppression collision density |
| Content Type | Text |
| Resource Type | Article |
