1,028 research outputs found
Di-hadron azimuthal correlation and Mach-like cone structure in parton/hadron transport model
In the framework of a multi-phase transport model (AMPT) with both partonic
and hadronic interactions, azimuthal correlations between trigger particles and
associated scattering particles have been studied by the mixing-event
technique. The momentum ranges of these particles are
GeV/ and GeV/ (soft), or 4
GeV/ and GeV/ (hard) in Au + Au collisions at
= 200 GeV. A Mach-like structure has been observed in
correlation functions for central collisions. By comparing scenarios with and
without parton cascade and hadronic rescattering, we show that both partonic
and hadronic dynamical mechanisms contribute to the Mach-like structure of the
associated particle azimuthal correlations. The contribution of hadronic
dynamical process can not be ignored in the emergence of Mach-like correlations
of the soft scattered associated hadrons. However, hadronic rescattering alone
cannot reproduce experimental amplitude of Mach-like cone on away-side, and the
parton cascade process is essential to describe experimental amplitude of
Mach-like cone on away-side. In addition, both the associated multiplicity and
the sum of decrease, whileas the increases, with the impact
parameter in the AMPT model including partonic dynamics from string melting
scenario.Comment: 9 pages, 5 figures; Physics Letters B 641, 362-367 (2006
Jet measurements in the ALICE experiment at the LHC
Jet tomography probes provide a means to explore the properties of highly
compressed and excited nuclear matter created in heavy ion collisions. The
capabilities of the ALICE experiment, with its electromagnetic calorimeter
(EMCal) upgrade, to trigger on and reconstruct jets in p+p and Pb+Pb collisions
at =5.5 TeV are presented.Comment: 8 pages, 6 figures. Presented at the IX International Conference on
Nucleus-Nucleus Collisions, Rio de Janeiro, Brazil, August 28 - September 1,
200
Continuum limit of the Volterra model, separation of variables and non standard realizations of the Virasoro Poisson bracket
The classical Volterra model, equipped with the Faddeev-Takhtadjan Poisson
bracket provides a lattice version of the Virasoro algebra. The Volterra model
being integrable, we can express the dynamical variables in terms of the so
called separated variables. Taking the continuum limit of these formulae, we
obtain the Virasoro generators written as determinants of infinite matrices,
the elements of which are constructed with a set of points lying on an infinite
genus Riemann surface. The coordinates of these points are separated variables
for an infinite set of Poisson commuting quantities including . The
scaling limit of the eigenvector can also be calculated explicitly, so that the
associated Schroedinger equation is in fact exactly solvable.Comment: Latex, 43 pages Synchronized with the to be published versio
Does the Charm Flow at RHIC?
Recent PHENIX Au+Au -> e- + X data from open charm decay are shown to be
consistent with two extreme opposite dynamical scenarios of ultra-relativistic
nuclear reactions. Perturbative QCD without final state interactions was
previously shown to be consistent with the data. However, we show that the data
are also consistent with zero mean free path hydrodynamics characterized by a
common transverse flow velocity field. The surprising coincidence of both D and
B hydrodynamic flow spectra with pQCD up to p_T ~ 3 and 5 GeV, respectively,
suggests that heavy quarks may be produced essentially at rest in the rapidly
expanding gluon plasma. Possible implications and further tests of collective
heavy quark dynamics are discussed.Comment: 10 pages, 3 figures, submitted to Phys. Lett.
On the pion electroproduction amplitude
We analyze amplitudes for the pion electroproduction on proton derived from
Lagrangians based on the local chiral SU(2) x SU(2) symmetries. We show that
such amplitudes do contain information on the nucleon axial form factor F_A in
both soft and hard pion regimes. This result invalidates recent Haberzettl's
claim that the pion electroproduction at threshold cannot be used to extract
any information regarding F_A.Comment: 14 pages, 6 figures, revised version, accepted for publication in
Phys. Rev.
Iso-singlet Down Quark Mixing And CP Violation Experiments
We confront the new physics models with extra iso-singlet down quarks in the
new CP violation experimental era with and
measurements, events, and
limits. The closeness of the new experimental results to the standard
model theory requires us to include full SM amplitudes in the analysis. In
models allowing mixing to a new isosinglet down quark, as in E, flavor
changing neutral currents are induced that allow a mediated contribution
to mixing and which bring in new phases. In ,
, and plots we still find much
larger regions in the four down quark model than in the SM, reaching down to
, , , and down to zero, all at 1. We elucidate
the nature of the cancellation in an order four down quark mixing
matrix element which satisfies the experiments and reduces the number of
independent angles and phases. We also evaluate tests of unitarity for the
CKM submatrix.Comment: 14 pages, 16 figures, REVTeX
Three-Particle Correlations from Parton Cascades in Au+Au Collisions
We present a study of three-particle correlations among a trigger particle
and two associated particles in Au + Au collisions at = 200 GeV
using a multi-phase transport model (AMPT) with both partonic and hadronic
interactions. We found that three-particle correlation densities in different
angular directions with respect to the triggered particle (`center', `cone',
`deflected', `near' and `near-away') increase with the number of participants.
The ratio of `deflected' to `cone' density approaches to 1.0 with the
increasing of number of participants, which indicates that partonic Mach-like
shock waves can be produced by strong parton cascades in central Au+Au
collisions.Comment: 9 pages, 6 figures; Final version to appear in Physics Letters
The Off-diagonal Goldberger-Treiman Relation and Its Discrepancy
We study the off-diagonal Goldberger-Treiman relation (ODGTR) and its
discrepancy (ODGTD) in the N, Delta, pi sector through O(p^2) using heavy
baryon chiral perturbation theory. To this order, the ODGTD and axial vector N
to Delta transition radius are determined solely by low energy constants. Loop
corrections appear at O(p^4). For low-energy constants of natural size, the
ODGTD would represent a ~ 2% correction to the ODGTR. We discuss the
implications of the ODGTR and ODGTD for lattice and quark model calculations of
the transition form factors and for parity-violating electroexcitation of the
Delta.Comment: 11 pages, 1 eps figur
Slowly synchronizing automata and digraphs
We present several infinite series of synchronizing automata for which the
minimum length of reset words is close to the square of the number of states.
These automata are closely related to primitive digraphs with large exponent.Comment: 13 pages, 5 figure
Universal behavior of baryons and mesons' transverse momentum distributions in the framework of percolation of strings
In the framework of percolation of strings, we present predictions for the
and for mesons and baryons and for ratios
at LHC energies.Comment: Presented at "Heavy Ion Collisions at the LHC: last call for
predictions", Geneva Switzerland, May 14th-June 8t
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