18335343
Search for squeezed-pair correlations at RHIC
Squeezed correlations of particle–antiparticle pairs, also called back-to-back correlations (BBC), are predicted to appear if the hadron masses are modified in the hot and dense hadronic medium formed in high energy nucleus–nucleus collisions. Although well established theoretically, the squeezed-particle correlations have not yet been searched for experimentally in high energy hadronic or heavy ion collisions, clearly requiring optimized forms to experimentally search for this effect. Within a non-relativistic treatment developed earlier we show that one promising way to search for the BBC signal is to look into the squeezed correlation function of pairs of 's at RHIC energies, plotted in terms of the average momentum of the pair, . This variable's modulus, 2|K12|, is the non-relativistic limit of the variable Qbbc, introduced herewith. Some squeezing effects on the HBT correlation function are also discussed.
125071872
Exact solutions of perfect fluid hydrodynamics: Theory and applications in high-energy experiments
Some exact and explicit solutions of the relativistic hydrodynamical equations are reviewed in context of high-energy heavy ion physics. Hydrodynamics is a powerful tool to describe the experimentally observed features (e.g. scaling laws) in the final state of high-energy collisions. Hydrodynamical solutions (both exact, analytic and numerical) can then be used to draw consequences on the initial state or the equation of state of the created matter. These findings can help to reach the ultimate goal of heavy-ion physics, the mapping of the phase structure of the strong interaction. In this paper we discuss exact and phenomenologically relevant solutions of hydrodynamics, and hint at some applications of them. We detail one important application: the estimation of the initial energy density from the observed final state.
30878089
Accelerating solutions of perfect fluid hydrodynamics for initial energy density and life-time measurements in heavy ion collisions
A new class of accelerating, exact, explicit and simple solutions of relativistic hydrodynamics is presented. Since these new solutions yield a finite rapidity distribution, they lead to an advanced estimate of the initial energy density and life-time of high energy heavy ion collisions. Accelerating solutions are also given for spherical expansions in arbitrary number of spatial dimensions.
119105321
New family of exact and rotating solutions of fireball hydrodynamics
A new class of analytic, exact, rotating, self-similar and surprisingly simple solutions of non-relativistic hydrodynamics are presented for a three-dimensionally expanding, spheroidally symmetric fireball. These results generalize earlier, non-rotating solutions for ellipsoidally symmetric fireballs with directional, three-dimensional Hubble flows. The solutions are presented for a general class of equations of state that includes the lattice QCD equations of state and may feature inhomogeneous temperature and corresponding density profiles.
16863322
Multi-boson correlations using wave-packets II
Abstract.
We investigate the analytically solvable pion-laser model, and generalize it to arbitrary multiplicity distributions.
We show that this kind of extension of the model is possible, but less interesting, than the already known one.
119143405
Detailed description of accelerating, simple solutions of relativistic perfect fluid hydrodynamics
In this paper we describe in full details a new family of recently found exact solutions of relativistic, perfect fluid dynamics. With an ansatz that generalizes the well-known Hwa-Bjorken solution we obtain a wide class of new exact, explicit, and simple solutions, which have a remarkable advantage as compared to presently known exact and explicit solutions: they do not lack acceleration. They can be utilized for the description of the evolution of the matter created in high energy heavy ion collisions. Because these solutions are accelerating, they provide a more realistic picture than the well-known Hwa-Bjorken solution, and give more insight into the dynamics of the matter. We exploit this by giving an advanced simple estimation of the initial energy density of the produced matter in high energy collisions, which takes acceleration effects, i.e., the work done by the pressure, and the modified change of the volume elements, into account. We also give an advanced estimation of the life-time of the reaction. Our new solutions can also be used to test numerical hydrodynamical codes reliably. In the end, we also give an exact, 1+1 dimensional, relativistic hydrodynamical solution, where the initial pressure and velocity profile is arbitrary, and we showmore » that this general solution is stable for perturbations.« less
120831306
Chiral perturbation theory at the quark level
The chiral perturbation theory is developed at the quark level within the extended Nambu-Jona-Lasinio model, which we used for the low-energy approximation of QCD in the leading order of the large N expansion. In terms of constituent-quark loop diagrams we analyze all of the main low-energy effects caused by the first order corrections in the current-quark-mass expansions. For the correct description of the η→3π decays we confirm the important role of the final-state interaction quoted by Gasser and Leutwyler.
16659233
Scalar mesons in the Nambu-Jona-Lasinio model with the ’t Hooft interaction
SummaryWe calculate the mass spectra of the pseudoscalar and scalar meson nonets in the Nambu-Jona-Lasinio model with the ’t Hooft interaction. We obtain satisfactory result for the pseudoscalar mesons. For the scalar mesons, the ’t Hooft interaction somewhat increases the values of the masses. However, it is not sufficient to explain the whole scalar mass spectrum. The situation could be improved for the φ and f0 mesons through mixing with the glueball state. For the description of the masses of a0 and K0* mesons, it is necessary to involve other models. The strong decay widths of scalar mesons are described.
122148735
The Existence of low lying mesons as a consequence of confinement
Abstract We use the Bethe-Salpeter equation for the investigation of the mass spectra of four nonets of low-lying mesons (pseudoscalar, scalar, vector and axial-vector) within QCD with a linearly rising potential. In leading order in the large- N expansion and in the chiral limit the mass spectra are found in agreement with those predicted by the extended Nambu-Jona-Lasinio model. We show that due to the confinement potential the nonets of vector and axial-vector mesons are stable under decays into quark-antiquark pairs.
120703177
IS THE CRONIN’S REPRESENTATION CORRECT FOR THE PENGUIN OPERATOR?
It is shown that the Cronin’s operator, being used for a phenomenological description of non-loptonic K-meson decays within the effective chiral Lagrangian approach with non-linear realization of chiral SU(3)×SU(3) symmetry (so-called, chiral perturbation theory at the hadronic level), cannot be applied to the determination of the Penguin-operator (O5-operator) at the hadronic level. The affirmation is based on the proof of the violation of the low-energy theorem $\lim _{P + \to 0} \left\langle {\pi ^ + \left( {p_ + } \right)\pi ^ - \left( {p_ - } \right)\left| {O_5 } \right|K^0 \left( p \right)} \right\rangle = \frac{i}{{F_\pi }}\left\langle {\pi ^0 \left( p \right)\left| {O_5 } \right|K^0 \left( p \right)} \right\rangle $ which is valid within the framework of the Cronin’s representation. The violation of this low-energy theorem is obtained at the quark level and connected with the account of the low-energy interactions of pions caused by the overlap of wave functions of pions in the |π+π−> state in the...
122534149
Chiral perturbation theory in the Extended Nambu-Jona-Lasinio model
The chiral perturbation theory is developed at the quark level within the Extended Nambu-Jona-Lasinio model which we used for the low-energy approximation of QCD in the leading order of the large N expansion. In terms of constituent-quark-loop diagrams we analyse all of the main low-energy effects caused by the first order corrections in the current quark mass expansions. For the correct description of theη →3π decays we confirm the important role of the final-state-interaction quoted by Gasser and Leutwyler.