125 research outputs found
Negative Elliptic Flow from Anomaly Induced DCC Formation
We discuss characteristic experimental signatures related to the mechanism of
DCC formation triggered by the chiral U(1) anomaly in relativistic heavy ion
collisions. We predict an enhancement of the fraction of neutral pions compared
with all pions in the direction perpendicular to the scattering plane. To
quantify the effect on the angular distribution of neutral pions, we compute
the elliptic flow parameter as a function of the transverse momentum. We
find values of order -0.05 at small momenta for neutral pions. We also compute
the parameter for inclusive photons, which is easier to measure, and
confirmed that the negative a few percent effect prevails in this observable.Comment: Contribution to PANIC 200
Fluctuation Probes of Quark Deconfinement
The size of the average fluctuations of net baryon number and electric charge
in a finite volume of hadronic matter differs widely between the confined and
deconfined phases. These differences may be exploited as indicators of the
formation of a quark-gluon plasma in relativistic heavy-ion collisions, because
fluctuations created in the initial state survive until freeze-out due to the
rapid expansion of the hot fireball.Comment: 4 pages RevTeX, 1 figure; submitted simultaneously with
hep-ph/0003168. Relative to v2 a typo was corrected, and the "Note added" was
expanded by a clarifying sentence. This version accepted by Physical Review
Letter
Third moments of conserved charges in QCD phase diagram
We point out that the third moments of conserved charges, the baryon and
electric charge numbers, and energy, as well as their mixed moments, change
their signs around the QCD phase boundary in the temperature and baryon
chemical potential plane. These signs can be measured in relativistic heavy ion
collisions, and will give clear information on the phase structure of QCD and
the state of the system in the early stage of relativistic heavy ion
collisions. The behaviors of these moments on the temperature axis and at small
quark chemical potential can be analyzed in lattice QCD simulations. We
emphasize that the third moments obtained on the lattice, together with the
experimental results, will provide a deep understanding about the QCD phase
diagram and the location of the state created in heavy ion collisions.Comment: 7 pages, 2 figures, Contribution to the "XXVII International
Symposium on Lattice Field Theory", July 26-31, 2009, Peking University,
Beijing, Chin
Nonequilibrium time evolution of higher order cumulants of conserved charges and event-by-event analysis
We investigate the time evolution of higher order cumulants of conserved
charges in a volume with the diffusion master equation. Applying the result to
the diffusion of non-Gaussian fluctuations in the hadronic stage of
relativistic heavy ion collisions, we show that the fourth-order cumulant of
net-electric charge at LHC energy is suppressed compared with the recently
observed second-order cumulant at ALICE, if the higher order cumulants at
hadronization are suppressed compared with their values in the hadron phase in
equilibrium. The significance of the experimental information on the rapidity
window dependence of various cumulants in investigating the history of the
dynamical evolution of the hot medium created in relativistic heavy ion
collisions is emphasized.Comment: 8 pages, 3 figure
Third moments of conserved charges as probes of QCD phase structure
The third moments of conserved charges, the baryon and electric charge
numbers, and energy, as well as their mixed moments, carry more information on
the state around the QCD phase boundary than previously proposed fluctuation
observables and higher order moments. In particular, their signs give plenty of
information on the location of the state created in relativistic heavy ion
collisions in the temperature and baryon chemical potential plane. We
demonstrate this with an effective model.Comment: 4 pages, 2 figures. Minor changes. To be published in Physical Review
Letter
Electric Charge Separation in Strong Transient Magnetic Fields
We discuss various mechanisms for the creation of an asymmetric charge
fluctuation with respect to the reaction plane among hadrons emitted in
relativistic heavy-ion collisions. We show that such mechanisms exist in both,
the hadronic gas and the partonic phases of QCD. The mechanisms considered here
all require the presence of a strong magnetic field (the ``chiral magnetic
effect''), but they do not involve parity or charge-parity violations. We
analyze how a transient local electric current fluctuation generated by the
chiral magnetic effect can dynamically evolve into an asymmetric charge
distribution among the final-state hadrons in momentum space. We estimate the
magnitude of the event-by-event fluctuations of the final-state charge
asymmetry due to the partonic and hadronic mechanisms
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