64,110 research outputs found
Probing the QCD Critical Point with Higher Moments of Net-proton Multiplicity Distributions
Higher moments of event-by-event net-proton multiplicity distributions are
applied to search for the QCD critical point in the heavy ion collisions. It
has been demonstrated that higher moments as well as moment products are
sensitive to the correlation length and directly connected to the thermodynamic
susceptibilities computed in the Lattice QCD and Hadron Resonance Gas (HRG)
model. In this paper, we will present measurements for kurtosis (),
skewness () and variance () of net-proton multiplicity
distributions at the mid-rapidity () and GeV/ for
Au+Au collisions at =19.6, 39, 62.4, 130 and 200 GeV, Cu+Cu
collisions at =22.4, 62.4 and 200 GeV, d+Au collisions at
=200 GeV and p+p collisions at =62.4 and 200 GeV.
The moment products and of net-proton
distributions, which are related to volume independent baryon number
susceptibility ratio, are compared to the Lattice QCD and HRG model
calculations. The and of net-proton
distributions are consistent with Lattice QCD and HRG model calculations at
high energy, which support the thermalization of the colliding system.
Deviations of and for the Au+Au collisions at
low energies from HRG model calculations are also observed.Comment: 10 pages, 8 figures, Proceedings of 27th Winter Workshon on Nuclear
Dynamics. Feb. 6-13 (2011
Simple model of bouncing ball dynamics: displacement of the table assumed as quadratic function of time
Nonlinear dynamics of a bouncing ball moving in gravitational field and
colliding with a moving limiter is considered. Displacement of the limiter is a
quadratic function of time. Several dynamical modes, such as fixed points, 2 -
cycles and chaotic bands are studied analytically and numerically. It is shown
that chaotic bands appear due to homoclinic structures created from unstable 2
- cycles in a corner-type bifurcation.Comment: 11 pages, 6 figure
Entanglement and quantum discord dynamics of two atoms under practical feedback control
We study the dynamics of two identical atoms resonantly coupled to a
single-mode cavity under practical feedback control, and focus on the detection
inefficiency. The entanglement is induced to vanish in finite time by the
inefficiency of detection. Counterintuitively, the asymptotic entanglement and
quantum discord can be increased by the inefficiency of detection. The noise of
detection triggers control field to create entanglement and discord when no
photon are emitted from the atoms. Furthermore, sudden change happens to the
dynamics of entanglement.Comment: 5 pages, 4 figure
Black Holes in the Presence of Cosmological Constant and Large N Brane World
Analytic form has been obtained for four-dimensional black holes with a
minimal Hawking temperature in a theory with cosmological constant, dilaton and
gauge fields. In general dimensions, black hole solutions are shown to exist
and their asymptotic behaviors are obtained. In theories of ten dimension, N
coincident D3-branes as the boundary of an space are constructed by
embedding black D3-branes, with a five-dimensional compactified space of
negligible size if N is large, which provide natural realizations of the
Randall-Sundrum scenario. For this background, the cosmological
constant is a higher order perturbation and its effect on the spectra of
standard model fields on the branes can be calculated.Comment: 12 pages, no figure
and the tree amplitude in
The recently-observed decay is expected to proceed
mainly by means of a tree amplitude in the factorization limit: , . Under this assumption, we predict the
corresponding contribution of the tree amplitude to . We
indicate the needed improvements in data that will allow a useful estimate of
this amplitude with errors comparable to those accompanying other methods.
Since the factorization hypothesis for this process goes beyond that proved in
most approaches, we also discuss independent tests of this hypothesis.Comment: 7 pages, LaTeX, 1 figure, to be submitted to Phys. Rev. D (Brief
Reports
Spherical geometry and integrable systems
We prove that the cosine law for spherical triangles and spherical tetrahedra
defines integrable systems, both in the sense of multidimensional consistency
and in the sense of dynamical systems.Comment: 15 pages, 5 figure
Unparticle effects in rare (t -> c g g) decay
Rare (t -> c g g) decay can only appear at loop level in the Standard Model
(SM), and naturally they are strongly suppressed. These flavor changing decays
induced by the mediation of spin-0 and spin-2 unparticles, can appear at tree
level in unparticle physics. In this work the virtual effects of unparticle
physics in the flavor-changing (t -> c g g) decay is studied. Using the SM
result for the branching ratio of the (t -> c g g) decay, the parameter space
of d_U and Lambda_U, where the branching ratio of this decay exceeds the one
predicted by the SM, is obtained. Measurement of the branching ratio larger
than 10^(-9) can give valuable information for establishing unparticle physics.Comment: 15 pages, 7 figures, LaTeX formatte
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