Finite Volume Cumulant Expansion in QCD-Colorless Plasma

Due to the finite size effects, the localisation of the phase transition in finite systems and the determination of its order, become an extremely difficult task, even in the simplest known cases. In order to identify and locate the finite volume transition point $T_{0}(V)$ of the QCD deconfinement phase transition to a Colorless QGP, we have developed a new approach using the finite size cumulant expansion of the order parameter and the $L_{mn}$-method. The first six cumulants $C_{1,2,3,4,5,6}$ with the corresponding under-normalized ratios(skewness $\Sigma$, kurtosis $\kappa$ ,pentosis $\Pi_{\pm}$ and hexosis $\mathcal{H}_{1,2,3}$) and three unnormalized combinations of them ($\mathcal{O}={\mathcal{\sigma }^{2} \mathcal{\kappa } }{\mathbf{\Sigma }^{-1} }$, $\mathcal{U} ={\mathcal{\sigma }^{-2} \mathbf{\Sigma }^{-1} }$, $\mathcal{N} = \mathcal{\sigma }^{2} \mathcal{\kappa }$) are calculated and studied as functions of $(T,V)$. A new approach, unifying in a clear and consistent way the definitions of cumulant ratios, is proposed. A numerical FSS analysis of the obtained results has allowed us to locate accurately the finite volume transition point. The extracted transition temperature value $T_{0}(V)$ agrees with that expected $T_{0}^{N}(V)$ from the order parameter and the thermal susceptibility $\chi _{T}\left( T,V\right)$, according to the standard procedure of localization to within about $2\%$. In addition to this, a very good correlation factor is obtained proving the validity of our cumulants method. The agreement of our results with those obtained by means of other models is remarkable.Comment: 19 pages,14 figues, figures 4,5,6 figures are oversized, therefore, can be obtained directly from [email protected],Accepted for publication in EPJ

Effect of colorlessness condition on phase transition from Hadronic Gas to partonic plasma

One of the most important phase transition in physics is the Deconfinement Phase Transition in thermal Quantum ChromoDynamics. Due to the confinement property, we study the effect of colorlessness condition during the Deconfinement Phase Transition from a Hadronic Gas to a Quark-Gluon Plasma. We investigate the behavior of some thermodynamical quantities of the system such as the energy density and the pressure, the colorlessness condition and without colorlessness

Finite-Size Effects and Scaling for the Thermal QCD Deconfinement Phase Transition within the Exact Color-Singlet Partition Function

We study the finite-size effects for the thermal QCD Deconfinement Phase Transition (DPT), and use a numerical finite size scaling analysis to extract the scaling exponents characterizing its scaling behavior when approaching the thermodynamic limit. For this, we use a simple model of coexistence of hadronic gas and color-singlet Quark Gluon Plasma (QGP) phases in a finite volume. The Color-Singlet Partition Function (CSPF) of the QGP cannot be exactly calculated and is usually derived within the saddle point approximation. When we try to do calculations with such an approximate CSPF, a problem arises in the limit of small temperatures and/or volumes (VT3<<1), requiring then additional approximations if we want to carry out calculations. We propose in this work a new method for an accurate calculation of any quantity of the finite system, without explicitly calculating the CSPF itself and without any approximation. By probing the behavior of some useful thermodynamic response functions on the hole range of temperature, it turns out that in a finite size system, all singularities in the thermodynamic limit are smeared out and the transition point is shifted away. A numerical finite size scaling analysis of the obtained data allows us to determine the scaling exponents of the QCD DPT. Our results expressing the equality between their values and the space dimensionality is a consequence of the singularity characterizing a first order phase transition and agree very well with the predictions of other FSS theoretical approaches and with the results of both lattice QCD and Monte Carlo models calculations.Comment: 09 pages, 11 Postscript figure

Measurement of negative particle multiplicity in S - Pb collisions at 200 GeV/c per nucleon with the NA36 TPC

A high statistics study of the negative multiplicity distribution from S-Pb collisions at 200 GeV/c per nucleon is presented. The NA36 TPC was used to detect charged particles; corrections are based upon the maximum entropy method.A high statistics study of the negative multiplicity distribution from S-Pb collisions at 200 GeV/c per nucleon is presented. The NA36 TPC was used to detect charged particles; corrections are based upon the maximum entropy method.A high statistics study of the negative particle multiplicity distribution from S–Pb collisions at 200 GeV/ c per nucleon is presented. The NA36 TPC was used to detect charged particles; corrections are based upon the maximum entropy method