The Chiral Magnetic Wave (CMW) [1] predicts a dependence of the positive and negative particle elliptic flow on the event charge asymmetry. Such a dependence has been observed by the STAR Collaboration [2]. However, it is rather difficult to interpre
t the results of this measurement, as well as to perform cross-experiment comparisons, due to the dependence of the observable on experimental inefficiencies and the kinematic acceptance used to determine the net asymmetry. We propose another observable that is free from these deficiencies. It also provides possibilities for differential measurements clarifying the interpretation of the results. We use this new observable to study the effect of the local charge conservation that can mimic the effect of the CMW in charge dependent flow measurements.
This short overview includes recent results from the ALICE Collaboration on anisotropic flow of charged and identified particles in sqrt(sNN) = 2.76 TeV Pb-Pb collisions. We also discuss charge dependent and event plane dependent azimuthal correlatio
ns that are important in tests of the chiral magnetic effect, as well as understanding the dynamics of the system evolution and hadronization process. Lastly, we present ALICE results obtained with a new technique, the event shape engineering, which allows to perform a physical analysis on events with very large or small flow.
The evolution of the system created in a high energy nuclear collision is very sensitive to the fluctuations in the initial geometry of the system. In this letter we show how one can utilize these large fluctuations to select events corresponding to
a specific initial shape. Such an event shape engineering opens many new possibilities in quantitative test of the theory of high energy nuclear collisions and understanding the properties of high density hot QCD matter.
Many features of multiparticle production in ultra-relativistic nuclear collisions reflect the collision geometry and other collision characteristics determining the initial conditions. As the initial conditions affect to a different degree all the p
articles, it leads to truly multiparticle effects often referred to as anisotropic collective flow. Studying anisotropic flow in nuclear collisions provides unique and invaluable information about the system evolution and the physics of multiparticle production in general. Being not able to cover all aspects of anisotropic flow in one lecture, I decided in the first part of the lecture to discuss briefly a few important and established results, and in the second part, to focus, in a little more detail, on one recent development -- a recent progress in our understanding of the role of fluctuations in the initial conditions. I also discuss some future measurements that might reveal further details of the multiparticle production processes.
Dipole, triangular, and higher harmonic flow that have an origin in the initial density fluctuations has gained a lot of attention as they can provide additional important information about the dynamical properties (e.g. viscosity) of the system. The
fluctuations in the initial geometry should be also reflected in the detail shape and velocity field of the system at freeze-out. In this talk I discuss the possibility to measure such fluctuations by means of identical and non-identical particle interferometry.
A quark interaction with topologically nontrivial gluonic fields, instantons and sphalerons, violates P~ and CP~ symmetry. In the strong magnetic field of a noncentral nuclear collision such interactions lead to the charge separation along the magnet
ic field, the so-called chiral magnetic effect (CME). Recent results from the STAR collaboration on charge dependent correlations are consistent with theoretical expectations for CME but may have contributions from other effects, which prevents definitive interpretation of the data. Here I propose to use central body-body $U+U$ collisions to disentangle correlations due to CME from possible background correlations due to elliptic flow. Further more quantitative studies can be performed with collision of isobaric beams.
Quark interaction with topologically non-trivial gluonic fields, instantons and sphalerons, violates P and CP symmetry. In the strong magnetic field of a non-central nuclear collision such interactions lead to the charge separation along the magnetic
field, the so called chiral magnetic effect, which manifests local parity violations. An experimental observation of the chiral magnetic effect would be a direct proof for the existence of such physics. Recent STAR results on charge and the reaction plane dependent correlations are consistent with theoretical expectations for the chiral magnetic effect. IIn this paper I discuss different approaches to experimental study of the local parity violation, and propose future measurements which can clarify the picture. In particular I propose to use central body-body U+U collisions to disentangle correlations due to chiral magnetic effect from possible background correlations due to elliptic flow. Further more quantitative studies can be performed with collision of isobaric beams.
Parity-odd domains, corresponding to non-trivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the orbital momentum of the
system created in non-central collisions. To study this effect, we investigate a three particle mixed harmonics azimuthal correlator which is a P-even observable, but directly sensitive to the charge separation effect. We report measurements of this observable using the STAR detector in Au+Au and Cu+Cu collisions at $sqrt{s_{NN}}$=200 and 62~GeV. The results are presented as a function of collision centrality, particle separation in rapidity, and particle transverse momentum. A signal consistent with several of the theoretical expectations is detected in all four data sets. We compare our results to the predictions of existing event generators, and discuss in detail possible contributions from other effects that are not related to parity violation.
