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Register a new userFinite size effects on cumulants of the critical mode
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In this work we study the temperature dependence of the equilibrium variance of critical fluctuations near the QCD critical point. In particular, we take the finite size of the fireball created in heavy-ion collisions into account and systematically obtain corrections to the leading-order result. We find that not only is the variance globally reduced in a finite size system, but for certain combinations of parameters a two-peak structure can develop for temperatures near the critical point.
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We study the dependence of the normalized moments of the net-proton multiplicity distributions on the definition of centrality in relativistic nuclear collisions at a beam energy of $sqrt{s_{mathrm{NN}}}= 7.7$ GeV. Using the UrQMD model as event generator we find that the centrality definition has a large effect on the extracted cumulant ratios. Furthermore we find that the finite efficiency for the determination of the centrality introduces an additional systematic uncertainty. Finally, we quantitatively investigate the effects of event-pile up and other possible spurious effects which may change the measured proton number. We find that pile-up alone is not sufficient to describe the data and show that a random double counting of events, adding significantly to the measured proton number, affects mainly the higher order cumulants in most central collisions.
The high-order cumulants and factorial cumulants of conserved charges are suggested to study the critical dynamics in heavy ion collisions. In this paper, using parametric representation of the 3-dimensional Ising model, the sign distribution on the phase diagram and temperature dependence of the cumulants and factorial cumulants is studied and compared. In the vicinity of the critical point, the cumulants and factorial cumulants can not be distinguished. Far away from the critical point, sign changes occur in the factorial cumulants comparing with the same order cumulants. The cause of these sign changes is analysed. They may be used to measure the distance to the critical point.
The 1S0 pairing gap associated with the inner crust of a neutron star is calculated, taking into account the coexistence of the nuclear lattice with the sea of free neutrons (finite size effects), as well as medium polarization effects associated with the exchange of density and spin fluctuations. Both effects are found to be important and to lead to an overall quenching of the pairing gap. This result, whose quantitative value is dependent on the effective interaction used to generate the single-particle levels, is a consequence of the balance between the attractive (repulsive) induced interaction arising from the exchange of density (spin) modes, balance which in turn is influenced by the presence of the protons and depends on the single-particle structure of the system.
The quantum chromodynamics (QCD) sum rules for the Delta baryons are analyzed by taking into account the finite-width effects, through explicit utilization of the Breit-Wigner shape. We apply a Monte-Carlo based analysis to the traditional and the parity-projected sum rules. The first Delta excitation state is also considered as a sub-continuum resonance and the widths are calculated using the mass values as input.
Along with masses of pion and sigma meson modes, their dissociation into quark medium provide a detail spectral structures of the chiral partners. Present article has studied a finite size effect on that detail structure of chiral partners by using the framework of Nambu-Jona-Lasinio model. Through this dissociation mechanism, their diffusions and conductions are also studied. The masses, widths, diffusion coefficients, conductivities of chiral partners are merged at different temperatures in restore phase of chiral symmetry, but merging points of all are shifted in lower temperature, when one introduce finite size effect into the picture. The strengths of diffusions and conductions are also reduced due to finite size consideration.
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