IMEF - Instituto de Matemática, Estatística e Física
URI permanente desta comunidadehttps://rihomolog.furg.br/handle/1/339
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15 resultados
Resultados da Pesquisa
- ItemComparison between classification using impact parameter and using number of participants in relativistic nuclear collisions(2004) Aguiar, Carlos Eduardo; Andrade, Rone Peterson Galvão de; Grassi, Frédérico; Hama, Yogiro; Socolowski Junior, OtavioUsing the hydrodynamical code NeXSPheRIO, we compare predictions as usually done in hydrodynamics, using centrality windows defined through the impact parameter, and as obtainable experimentally, using windows in participant number.
- ItemSearching for squeezed particle-antiparticle correlations in high-energy heavy-ion collisions(2010) Padula, Sandra dos Santos; Socolowski Junior, OtavioSqueezed correlations of particle antiparticle pairs were predicted to exist if the hadron masses were modified in the hot and dense medium formed in high energy heavy ion collisions. Although well-established theoretically,they have not yet been observed experimentally.We suggest here a clear method to search for such signal, by analyzing the squeezed correlation functions in terms of measurable quantities.We illustrate this suggestion for simulated pairs at RHIC energies.
- ItemParticle abundances and spectra in the hydrodynamical description of relativistic nuclear collisions with light projectile(2004) Grassi, Frédérico; Hama, Yogiro; Kodama, Takeshi; Socolowski Junior, OtavioWe show that a hydrodynamical model with continuous particle emission instead of sudden freeze out may explain both the observed strange particle and pion abundances and transverse mass spectra for light projectile at SPS energy. We found that the observed enhancement of pion production corresponds, within the context of continuous emission, to the maximal entropy production.
- ItemSqueezed particle-antiparticle correlations(2009) Padula, Sandra dos Santos; Dudek, Danuce Marcele; Socolowski Junior, OtavioA novel type of correlation involving particle-antiparticle pairs was found out in the 1990’s. Currently known as squeezed or Back-to-Back Correlations (BBC), they should be present if the hadronic masses are modified in the hot and dense medium formed in high energy heavy ion collisions. Although well-established theoretically, such hadronic correlations have not yet been observed experimentally. In this phenomenological study we suggest a promising way to search for the BBC signal, by looking into the squeezed correlation function of and K+K− pairs at RHIC energies, as function of the pair average momentum, K12=(k1 + k2)/2. The effects of in-medium mass-shift on the identical particle correlations (Hanbury-Brown & Twiss effect) are also discussed.
- Item3D relativistic hydrodynamic computations using lattice-QCD-inspired equations of state(2006) Hama, Yogiro; Andrade, Rone Peterson Galvão de; Grassi, Frédérico; Socolowski Junior, Otavio; Kodama, Takeshi; Tavares, Bernado; Padula, Sandra dos SantosIn This communication, we report results of three-dimensional hydrodynamic computations, by using equations of state with a critical end point as suggested by the lattice QCD. Some of the results are an increase of the multiplicity in the mid-rapidity region and a larger elliptic-flow parameter v2 . We discuss also the effcts of the initial condition fluctuations and the continuous emission.
- ItemSearch for squeezed-pair correlations at RHIC(2008) Padula, Sandra dos Santos; Socolowski Junior, Otavio; Csörgö, Tamás; Nagy, MartónSqueezed correlations of particle antiparticle pairs, also called Back-to- Back Correlations, 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 nonrelativistic 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 averagemomentum of the pair, K12=1 2(k1 + k2). This variable’s modulus, 2|K12|, is the non-relativistic limit of the variable Qbbc, introduced herewith. The squeezing effects on the HBT correlation function are also discussed.
- ItemSqueezed correlations of strange particles antiparticles(2010) Padula, Sandra dos Santos; Dudek, Danuce Marcele; Socolowski Junior, OtavioSqueezed correlations of hadron-antihadron pairs are predicted to appear if their masses are modified in the hot and dense medium formed in high energy heavy ion collisions. If discovered experimentally, they would be an unequivocal evidence of in-medium mass shift found by means of hadronic probes. We discuss a method proposed to search for this novel type of correlation, illustrating it by means of Ds- mesons with in-medium shifted masses. These particles are expected to be more easily detected and identified in future upgrades at RHIC.
- ItemUpdate on the status of hadronic squeezed correlations at RHIC energies(2011) Padula, Sandra dos Santos; Dudek, Danuce Marcele; Socolowski Junior, OtavioIn high-energy heavy-ion collisions, a hot and dense medium is formed, where the hadronic masses may be shifted from their asymptotic values. If this mass modiˇcation occurs, squeezed back-to-back correlations (BBC) of particleÄantiparticle pairs are predicted to appear, both in the fermionic (fBBC) and in the bosonic (bBBC) sectors. Although they have unlimited intensity even for ˇnite-size expanding systems, these hadronic squeezed correlations are very sensitive to their time emission distribution. Here we discuss results in case this time emission is parameterized by a L evy-type distribution, showing that it reduces the signal even more dramatically than a Lorentzian distribution, which already reduces the intensity of the effect by orders of magnitude, as compared to the sudden emission. However, we show that the signal could still survive if the duration of the process is short, and if the effect is searched for lighter mesons, such as kaons. We compare some of our results to recent PHENIX preliminary data on squeezed correlations of K+K − pairs.
- ItemEffect of chemical freeze-out on identified particle spectra at 200A GeV Au-Au collisions at RHIC using SPheRIO(2007) Qiam, Wei-Liang; Andrade, Rone Peterson Galvão de; Grassi, Frédérico; Socolowski Junior, Otavio; Kodama, Takeshi; Rama, YogiroWe investigate the effect of chemical freeze-out on identified particle spectra at 200AGeV Au-Au Collisions at RHIC, by utilizing a full three-dimensional hydrodynamical calculation. The hydrodynamical code SPheRIO we employed is based on the smoothed particle hydrodynamic algorithm. In order to describe the spectra of strange hadrons, the code has been further improved by explicitly incorporating the strangeness conservation and a chemical freeze-out mechanism. In our model, strange hadrons such as , , and undergo the chemical freeze-out immediately after the hadronization, and their multiplicitiesare fixed thereafter. At a lower temperature the thermal freeze-out takes place for all the particles. It is shown that the present model provides a reasonably good description for the spectra of identified particles, in particular, considerable improvement is observed for those of strange hadrons.
- ItemHBT Effect with fluctuating initial conditions and continuous emission(2005) Hama, Yogiro; Grassi, Frédérico; Socolowski Junior, OtavioWe study effects of the event-by-event fluctuation of the initial conditions and the continuous pion emission during the whole development of the hot and dense matter formed in high-energy collisions on the two-pion interferometry. Important deviations occur, from the standard version of hydrodynamics with smooth initial conditions and a sudden freeze-out on a T = Tfo hypersurface. Comparison with data at RHIC shows that this description can give account of the mT dependence of RL and Rs and significantly improves Ro with respect to the usual version.