2,060 research outputs found
Effects of Cluster Particle Correlations on Local Parity Violation Observables
We investigate effects of cluster particle correlations on two- and
three-particle azimuth correlator observables sensitive to local strong parity
violation. We use two-particle angular correlation measurements as input and
estimate the magnitudes of the effects with straightforward assumptions. We
found that the measurements of the azimuth correlator observables by the STAR
experiment can be entirely accounted for by cluster particle correlations
together with a reasonable range of cluster anisotropy in non-peripheral
collisions. Our result suggests that new physics, such as local strong parity
violation, may not be required to explain the correlator data.Comment: 11 pages, 3 figures, 1 table, published versio
Charge dependent correlations with identified hadrons relative to the reaction plane with the ALICE experiment at the LHC
Chiral Magnetic conductivity
Gluon field configurations with nonzero topological charge generate
chirality, inducing P- and CP-odd effects. When a magnetic field is applied to
a system with nonzero chirality, an electromagnetic current is generated along
the direction of the magnetic field. The induced current is equal to the Chiral
Magnetic conductivity times the magnetic field. In this article we will compute
the Chiral Magnetic conductivity of a high-temperature plasma for nonzero
frequencies. This allows us to discuss the effects of time-dependent magnetic
fields, such as produced in heavy ion collisions, on chirally asymmetric
systems.Comment: 10 pages, 4 figure
CBM Performance for Anisotropic Flow Measurements
Compressed Baryonic Matter experiment (CBM) at FAIR has a potential of discoveries in the area of QCD phase diagram with high net baryon densities and moderate temperatures. Anisotropic transverse flow is one of the key observables to study the properties of matter created in heavy-ion collisions. CBM performance for anisotropic flow measurements is studied with Monte-Carlo simulations of gold ions at SIS-100 energies using heavy-ion event generators. Different combinations of the CBM detector subsystems are used to investigate the possible systematic biases in flow measurement and to study effects of detector azimuthal non-uniformity. Resulting performance of the CBM for flow measurements is demonstrated for directed flow of identified charged hadrons as a function of rapidity and transverse momentum in different centrality classes
Event-by-event background in estimates of the chiral magnetic effect
In terms of the parton-hadron-string-dynamics (PHSD) approach - including the
retarded electromagnetic field - we investigate the role of fluctuations of the
correlation function in the azimuthal angle of charged hadrons that is
expected to be a sensitive signal of local strong parity violation. For the
early time we consider fluctuations in the position of charged spectators
resulting in electromagnetic field fluctuations as well as in the position of
participant baryons defining the event plane. For partonic and hadronic phases
in intermediate stages of the interaction we study the possible formation of
excited matter in electric charge dipole and quadrupole form as generated by
fluctuations. The role of the transverse momentum and local charge conservation
laws in the observed azimuthal asymmetry is investigated, too. All these
above-mentioned effects are incorporated in our analysis based on
event-by-event PHSD calculations. Furthermore, the azimuthal angular
correlations from Au+Au collisions observed in the recent STAR measurements
within the RHIC Beam-Energy-Scan (BES) program are studied. It is shown that
the STAR correlation data at the collision energies of = 7.7
and 11.5 GeV can be reasonably reproduced within the PHSD. At higher energies
the model fails to describe the correlation data resulting in an
overestimation of the partonic scalar field involved. We conclude that an
additional transverse anisotropy fluctuating source is needed which with a
comparable strength acts on both in- and out-of-plane components.Comment: 20 pages, 19 figures, to be published in Phys. Rev.
Global polarization of QGP in non-central heavy ion collisions at high energies
Due to the presence of a large orbital angular momentum of the parton system
produced at the early stage of non-central heavy-ion collisions, quarks and
anti-quarks are shown to be polarized in the direction opposite to the reaction
plane which is determined by the impact-parameter and the beam momentum. The
global quark polarization via elastic scattering was first calculated in an
effective static potential model, then using QCD at finite temperature with the
hard-thermal-loop re-summed gluon propagator. The measurable consequences are
discussed. Global hyperon polarization from the hadronization of polarized
quarks are predicted independent of the hadronization scenarios. It has also
been shown that the global polarization of quarks and anti-quarks leads also to
spin alignment of vector mesons. Dedicated measurements at RHIC are underway
and some of the preliminary results are obtained. In this presentation, the
basic idea and main results of global quark polarization are presented. The
direct consequences such as global hyperon polarization and spin alignment are
summarized.Comment: plenary talk at the 19th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions (QM2006), Shanghai, China,
November 14-20, 200
Quark electric dipole moment induced by magnetic field
We show numerically that quarks develop an electric dipole moment in the
direction of a sufficiently intense magnetic field due to local fluctuations of
topological charge. This anomalous CP-odd effect is a spin analogue of the
Chiral Magnetic Effect in QCD.Comment: 6 pages, 4 figures, RevTex 4.0; revision: comments added, published
versio
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