1,081 research outputs found
Probing Hadronization with Strangeness
The Omega-bar/Omega ratio originating from string decays is predicted to be
larger than unity in proton-proton interaction at SPS energies. The anti-omega
dominance increases with decreasing beam energy. This surprising behavior is
caused by the combinatorics of quark-antiquark production in small and low-mass
strings. Since this behavior is not found in a statistical description of
hadron production in proton-proton collisions, it may serve as a key observable
to probe the hadronization mechanism in such collisions.Comment: 10 pages, proceedings of the 18th International Winter Workshop on
Nuclear Dynamics, Nassau, Bahamas, January 200
Dark solitons in holographic superfluids
5 pages, Revtex, 5 figures, some typos corrected. Reference addedWe construct dark soliton solutions in a holographic model of a relativistic superfluid. We study the length scales associated with the condensate and the charge density depletion, and find that the two scales differ by a non-trivial function of the chemical potential. By adjusting the chemical potential, we study the variation of the depletion of charge density at the interface.Peer reviewe
Modified Boltzmann Transport Equation and Freeze Out
We study Freeze Out process in high energy heavy ion reaction. The
description of the process is based on the Boltzmann Transport Equation (BTE).
We point out the basic limitations of the BTE approach and introduce Modified
BTE. The Freeze Out dynamics is presented in the 4-dimensional space-time in a
layer of finite thickness, and we employ Modified BTE for the realistic Freeze
Out description.Comment: 9 pages, 2 figure
The Many Phases of Holographic Superfluids
We investigate holographic superfluids in AdS_{d+1} with d=3,4 in the
non-backreacted approximation for various masses of the scalar field. In d=3
the phase structure is universal for all the masses that we consider: the
critical temperature decreases as the superfluid velocity increases, and as it
is cranked high enough, the order of the phase transition changes from second
to first. Surprisingly, in d=4 we find that the phase structure is more
intricate. For sufficiently high mass, there is always a second order phase
transition to the normal phase, no matter how high the superfluid velocity. For
some parameters, as we lower the temperature, this transition happens before a
first order transition to a new superconducting phase. Across this first order
transition, the gap in the transverse conductivity jumps from almost zero to
about half its maximum value. We also introduce a double scaling limit where we
can study the phase transitions (semi-)analytically in the large velocity
limit. The results corroborate and complement our numerical results. In d=4,
this approach has the virtue of being fully analytically tractable.Comment: 31 pages, 19 figure
The Quark-Gluon Plasma in a Finite Volume
The statistical mechanics of quarks and gluons are investigated within the
context of the canonical ensemble. Recursive techniques are developed which
enforce the exact conservation of baryon number, total isospin, electric
charge, strangeness, and color. Bose and Fermi-Dirac statistics are also
accounted for to all orders. The energy, entropy and particle number densities
are shown to be significantly reduced for volumes less than 5 cubic fm.Comment: 8 pages, 3 figure
Emergent Gauge Fields in Holographic Superconductors
Holographic superconductors have been studied so far in the absence of
dynamical electromagnetic fields, namely in the limit in which they coincide
with holographic superfluids. It is possible, however, to introduce dynamical
gauge fields if a Neumann-type boundary condition is imposed on the
AdS-boundary. In 3+1 dimensions, the dual theory is a 2+1 dimensional CFT whose
spectrum contains a massless gauge field, signaling the emergence of a gauge
symmetry. We study the impact of a dynamical gauge field in vortex
configurations where it is known to significantly affect the energetics and
phase transitions. We calculate the critical magnetic fields H_c1 and H_c2,
obtaining that holographic superconductors are of Type II (H_c1 < H_c2). We
extend the study to 4+1 dimensions where the gauge field does not appear as an
emergent phenomena, but can be introduced, by a proper renormalization, as an
external dynamical field. We also compare our predictions with those arising
from a Ginzburg-Landau theory and identify the generic properties of Abrikosov
vortices in holographic models.Comment: 19 pages, 14 figures, few comments added, version published in JHE
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