2,102 research outputs found
Secondary phi meson peak as an indicator of QCD phase transition in ultrarelativistic heavy ion collisions
In a previous paper, we have shown that a double phi peak structure appears
in the dilepton invariant mass spectrum if a first order QCD phase transition
occurs in ultrarelativistic heavy ion collisions. Furthermore, the transition
temperature can be determined from the transverse momentum distribution of the
low mass phi peak. In this work, we extend the study to the case that a smooth
crossover occurs in the quark-gluon plasma to the hadronic matter transition.
We find that the double phi peak structure still exists in the dilepton
spectrum and thus remains a viable signal for the formation of the quark-gluon
plasma in ultrarelativistic heavy ion collisions.Comment: 8 pages, 9 uuencoded postscript figures included, Latex, LBL-3572
Non-Gaussian fluctuations near the QCD critical point
We study the effect of the QCD critical point on non-Gaussian moments
(cumulants) of fluctuations of experimental observables in heavy-ion
collisions. We find that these moments are very sensitive to the proximity of
the critical point, as measured by the magnitude of the correlation length xi.
For example, the cubic central moment of multiplicity ~ xi^4.5 and the quartic
cumulant ~ xi^7. We estimate the magnitude of critical point contributions to
non-Gaussian fluctuations of pion and proton multiplicities.Comment: 4 pages, 3 figure
On the q-deformation of the NJL model
Using a q-deformed fermionic algebra we perform explicitly a deformation of
the Nambu-Jona-Lasinio (NJL) Hamiltonian. In the Bogoliubov-Valatin approach we
obtain the deformed version of the functional for the total energy, which is
minimized to obtain the corresponding gap equation. The breaking of chiral
symmetry and its restoration in the limit are then discussed.Comment: 5 eps figure
Transverse Velocity Dependence of the Proton-Antiproton Ratio as a Signature of the QCD Critical Endpoint
The presence of a critical point in the QCD phase diagram can deform the
trajectories describing the evolution of the expanding fireball in the
phase diagram. If the average emission time of hadrons is a function
of transverse velocity, as microscopic simulations of the hadronic freeze-out
dynamics suggest, the deformation of the hydrodynamic trajectories will change
the transverse velocity () dependence of the proton-antiproton
ratio when the fireball passes in the vicinity of the critical point. An
unusual -dependence of the ratio in a narrow beam
energy window would thus signal the presence of the critical point.Comment: Final version accepted for publicatio
Center Domains and their Phenomenological Consequences
We argue that the domain structure of deconfined QCD matter, which can be
inferred from the properties of the Polyakov loop, can simultaneously explain
the two most prominent experimentally verified features of the quark-gluon
plasma, namely its large opacity as well as its near ideal fluid properties
The Present and Future of Museum Accessibility for People with Visual Impairments
People with visual impairments (PVI) have shown interest in visiting museums and enjoying visual art. Based on this knowledge, some museums provide tactile reproductions of artworks, specialized tours for PVI, or enable them to schedule accessible visits. However, the ability of PVI to visit museums is still dependent on the assistance they get from their family and friends or from the museum personnel. In this paper, we surveyed 19 PVI to understand their opinions and expectations about visiting museums independently, as well as the requirements of user interfaces to support it. Moreover, we increase the knowledge about the previous experiences, motivations and accessibility issues of PVI in museums
Wilson-like real-space renormalization group and low-energy effective spectrum of the XXZ chain in the critical regime
We present a novel real-space renormalization group(RG) for the
one-dimensional XXZ model in the critical regime, reconsidering the role of the
cut-off parameter in Wilson's RG for the Kondo impurity problem. We then
demonstrate the RG calculation for the XXZ chain with the free boundary.
Comparing the hierarchical structure of the obtained low-energy spectrum with
the Bethe ansatz result, we find that the proper scaling dimension is
reproduced as a fixed point of the RG transformation.Comment: 4 pages, 6 figures, typos corrected, final versio
Possible Resolutions of the D-Paradox
We propose possible ways of explaining the net charge event-by-event
fluctuations in Au+Au collisions at the Relativistic Heavy Ion Collider within
a quark recombination model. We discuss various methods of estimating the
number of quarks at recombination and their implications for the predicted net
charge fluctuations. We also discuss the possibility of diquark and
quark-antiquark clustering above the deconfinement temperature.Comment: 5 pages, 2 figure
Spectral density analysis of time correlation functions in lattice QCD using the maximum entropy method
We study various aspects of extracting spectral information from time
correlation functions of lattice QCD by means of Bayesian inference with an
entropic prior, the maximum entropy method (MEM). Correlator functions of a
heavy-light meson-meson system serve as a repository for lattice data with
diverse statistical quality. Attention is given to spectral mass density
functions, inferred from the data, and their dependence on the parameters of
the MEM. We propose to employ simulated annealing, or cooling, to solve the
Bayesian inference problem, and discuss practical issues of the approach.Comment: 11 pages, 30 figure files (eps), some references added and updated,
requires REVTeX 4.0 and prerequisites (AMS-LaTeX 2.0, graphicx, dcolumn, bm)
see http://publish.aps.org/revtex4
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