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Search Results: 1 - 10 of 333448 matches for " Sandra S. Padula "
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HBT interferometry: historical perspective
Padula, Sandra S.;
Brazilian Journal of Physics , 2005, DOI: 10.1590/S0103-97332005000100005
Abstract: i review the history of hbt interferometry, since its discovery in the mid 1950's, up to the recent developments and results from bnl/rhic experiments. i focus the discussion on the contributions to the subject given by members of our brazilian group.
Possible Origin of RHIC R_{out}/R_{sid} HBT Results
Sandra S. Padula
Physics , 2002, DOI: 10.1016/S0375-9474(02)01550-6
Abstract: The effects of opacity of the nuclei together with a blackbody type of emission along the system history are considered as a means to explain the ratio $R_{out}/R_{sid}$ observed by STAR and PHENIX collaborations at RHIC. Within our model, no flow is required to explain the data trend of this ratio for large surface emissivities.
HBT Interferometry: Historical Perspective
Sandra S. Padula
Physics , 2004, DOI: 10.1590/S0103-97332005000100005
Abstract: I review the history of HBT interferometry, since its discovery in the mid 1950's, up to the recent developments and results from BNL/RHIC experiments. I focus the discussion on the contributions to the subject given by members of our Brazilian group.
Resolving Power of 2-D Pion Interferometry
Sandra S. Padula,Miklos Gyulassy
Physics , 1995, DOI: 10.1016/0370-2693(95)00166-I
Abstract: A $\chi^2$ analysis is performed to test the resolving power of two-dimensional pion interferometry using for illustration the preliminary E802 data on $Si+Au$ at 14.6 AGeV/c. We find that the resolving power to distinguish two decoupling geometries of different dynamical models is enhanced by studying the variation of the mean $\chi^2$ per degrees of freedom with respect to the range of the analysis in the $q_T,q_L$ plane. The preliminary data seem to rule out dynamical models with significant $\omega,\eta$ resonance formation yields.
Multidimensional analysis of Bose-Einstein correlations in pp collisions at 2.76 and 7 TeV in CMS
Sandra S. Padula,for the CMS Collaboration
Physics , 2015,
Abstract: Multidimensional two-particle Bose-Einstein correlation functions of charged hadrons are reported for pp collisions at 2.76 and 7 TeV in terms of different components of the pair relative momentum, extending the previous one-dimensional (1-D) analyses of CMS. This allows for investigating the extension of the source accessible to the femtoscopic correlation technique in different directions, revealing a more detailed picture of the emitting source in these collisions at increasing energies. The measurements are performed for different intervals of the pair average transverse momentum, kT, and for increasing charged particle multiplicitiy, Nch. Results in 1-D, 2-D and 3-D show a decrease of the fit radius parameters with kT, whereas a clear rise with Nch is observed in all cases. In addition, the fit radius parameters at both energies show close similarity in size and behavior within the same intervals of (Nch,kT).
Disappearance of Squeezed Back-to-Back Correlations - a new signal of hadron freeze-out from a supercooled Quark Gluon Plasma
T. Csorgo,Sandra S. Padula
Physics , 2007, DOI: 10.1590/S0103-97332007000600012
Abstract: We briefly discuss four different possible types of transitions from quark to hadronic matter and their characteristic signatures in terms of correlations. We also highlight the effects arising from mass modification of hadrons in hot and dense hadronic matter, as well as their quantum statistical consequences: the appearance of squeezed quantum states and the associated experimental signatures, i.e., the back-to-back correlations of particle - anti-particle pairs. We briefly review the theoretical results of these squeezed quanta, generated by in-medium modified masses, starting from the first indication of the existence of surprising particle - anti-particle correlations, and ending by considering the effects of chiral dynamics on these correlation patterns. A prerequisite for such a signature is the experimental verification that these theoretically predicted back-to-back correlation of particle anti-particle pairs are, in fact, observable in high energy heavy ion reactions. Therefore, the experimental observation of back-to-back correlations in high energy heavy ion reactions would be a unique signature, proving the existence of in-medium mass modification of hadronic states. On the other hand, their disappearance at some threshold centrality or collision energy would indicate that the hadron formation mechanism would have qualitatively changed: asymptotic hadrons above such a threshold are not formed from medium modified hadrons anymore, but rather by new degrees of freedom characterizing the medium. Furthermore, the disappearance of the squeezed BBC could also serve as a signature of a sudden, non-equilibrium hadronization scenario from a supercooled quark-gluon plasma phase.
R_{out}/R_{sid} and Opacity at RHIC
Larry McLerran,Sandra S. Padula
Physics , 2002,
Abstract: One of the most dramatic results from the first RHIC run are the STAR results for pi+- pi+- interferometry. They showed that the ratio of the so-called R_{out} and R_{sid} radii seem to decrease below unity for increasing transverse momentum of the pair (K_T). This was subsequently confirmed by PHENIX, which also extended the K_T range of the measurements. We consider here the effects of opacity of the nuclei on this ratio, and find that such a small value is consistent with surface emission from an opaque source.
Disappearance of squeezed back-to-back correlations: a new signal of hadron freeze-out from a supercooled quark gluon plasma
Cs?rgo, T.;Padula, Sandra S.;
Brazilian Journal of Physics , 2007, DOI: 10.1590/S0103-97332007000600012
Abstract: we briefly discuss four different possible types of transitions from quark to hadronic matter and their characteristic signatures in terms of correlations. we also highlight the effects arising from mass modification of hadrons in hot and dense hadronic matter, as well as their quantum statistical consequences: the appearance of squeezed quantum states and the associated experimental signatures, i.e., the back-to-back correlations of particle-antiparticle pairs. we briefly review the theoretical results of these squeezed quanta, generated by in-medium modified masses, starting from the first indication of the existence of surprising particle-antiparticle correlations, and ending by considering the effects of chiral dynamics on these correlation patterns. nevertheless, a prerequisite for such a signature is the experimental verification of its observability. therefore, the experimental observation of back-to-back correlations in high energy heavy ion reactions would be a unique signature, proving the existence of in-medium mass modification of hadronic states. on the other hand, their disappearance at some threshold centrality or collision energy would indicate that the hadron formation mechanism would have qualitatively changed: asymptotic hadrons above such a threshold are not formed from medium modified hadrons anymore, but rather by new degrees of freedom characterizing the medium. furthermore, the disappearance of the squeezed bbc could also serve as a signature of a sudden, non-equilibrium hadronization scenario from a supercooled quark-gluon plasma phase.
Searching for squeezed particle-antiparticle correlations in high energy heavy ion collisions
Sandra S. Padula,O. Socolowski Jr
Physics , 2009, DOI: 10.1103/PhysRevC.82.034908
Abstract: Squeezed 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 phi-phi pairs at RHIC energies.
HBT Interferometry for Sonoluminescence Bubble
Y. Hama,T. Kodama,Sandra S. Padula
Physics , 1996, DOI: 10.1103/PhysRevA.56.2233
Abstract: The two-photon correlation of the light pulse emitted from a sonoluminescence bubble is discussed. It is shown that several important information about the mechanism of light emission, such as the time-scale and the shape of the emission region could be obtained from the HBT interferometry. We also argue that such a measurement may serve to reject one of the two currently suggested emission mechanisms, i.e., thermal process versus dynamical Casimir effect.
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