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 system's orbital momentum axis. We investigate a three particle azimuthal correlator which is a P even observable, but directly sensitive to the charge separation effect. We report measurements of charged hadrons near center-of-mass rapidity with this observable in Au+Au and Cu+Cu collisions at √ sNN =200 GeV using the STAR detector. A signal consistent with several expectations from the theory is detected. We discuss possible contributions from other effects that are not related to parity violation.

Recently, there has been significant interest in understanding the macroscopic quantum transport in a many-body system of chiral fermions. A natural framework for describing such a system that is generally out of equilibrium is the transport equation for its phase space distribution function. In this paper, we obtain a complete solution of the covariant chiral transport for massless fermions, by starting from the general Wigner function formalism and carrying out a complete and consistent semiclassical expansion up toÔðℏÞ order. In particular, we clarify certain subtle and confusing issues surrounding the Lorentz noninvariance and frame dependence associated with the three-dimensional chiral kinetic theory. We prove that such frame dependence is uniquely and completely fixed by an unambiguous definition of theÔðℏÞ correction to the distribution function in each reference frame.

Chiral anomaly is a fundamental aspect of quantum theories with chiral fermions. How such microscopic anomaly manifests itself in a macroscopic many-body system with chiral fermions, is a highly nontrivial question that has recently attracted significant interest. As it turns out, unusual transport currents can be induced by chiral anomaly under suitable conditions in such systems, with the notable example of the Chiral Magnetic Effect (CME) where a vector current (e.g. electric current) is generated along an external magnetic field.A lot of efforts have been made to search for CME in heavy ion collisions, by measuring the charge separation effect induced by the CME transport. A crucial challenge in such effort, is the quantitative prediction for the CME signal. In this paper, we develop the Anomalous-Viscous Fluid Dynamics (AVFD) framework, which implements the anomalous fluid dynamics to describe the evolution of fermion currents in QGP, on top of the neutral bulk background described by the VISH2+1 hydrodynamic simulations for heavy ion colli-arXiv:1711.02496v2 [nucl-th]

The results of midrapidity (0 < y < 0.8) neutral pion spectra over an extended transverse momentum range (1 < p T < 12 GeV/c) in √ s NN = 200 GeV Au + Au collisions, measured by the STAR experiment, are presented. The neutral pions are reconstructed from photons measured either by the STAR Barrel Electro-Magnetic Calorimeter or by the Time Projection Chamber via tracking of conversion electron-positron pairs. Our measurements are compared to previously published π ± and π 0 results. The nuclear modification factors R CP and R AA of π 0 are also presented as a function of p T . In the most central Au + Au collisions, the binary collision scaled π 0 yield at high p T is suppressed by a factor of about 5 compared to the expectation from the yield of p + p collisions. Such a large suppression is in agreement with previous observations for light quark mesons and is consistent with the scenario that partons suffer considerable energy loss in the dense medium formed in central nucleus-nucleus collisions at the Relativistic Heavy Ion Collider.

The Chiral Magnetic Effect (CME) is a macroscopic manifestation of fundamental chiral anomaly in a many-body system of chiral fermions, and emerges as anomalous transport current in the fluid dynamics framework. Experimental observation of CME is of great interest and has been reported in Dirac and Weyl semimetals. Significant efforts have also been made to look for CME in heavy ion collisions. Critically needed for such search, is the theoretical prediction for CME signal. In this paper we report a first quantitative modeling framework, the Anomalous Viscous Fluid Dynamics (AVFD), which computes the evolution of fermion currents on top of realistic bulk evolution in heavy ion collisions and simultaneously accounts for both anomalous and normal viscous transport effects. The AVFD allows a quantitative understanding of the generation and evolution of CME-induced charge separation during hydrodynamic stage as well as its dependence on theoretical ingredients. With reasonable estimates of key parameters, the AVFD simulations provide the first phenomenologically successful explanation of the measured signal in 200AGeV AuAu collisions.Introduction.-The importance of electricity for modern society cannot be overemphasized. From the physics point of view, lies at the heart of electricity is the conducting transport (of electric charge carriers). In normal materials, conducting transport generates an electric current J Q along the electric field E (or voltage) applied to the system. This can be described by the usual Ohm's law J Q = σ e E where the conductivity σ e arises from competition between "ordered" electric force and "disordered" thermal scatterings, henceforth involving dissipation and typically dependent upon specific dynamics of the system. More recently there have been significant interests, from both high energy and condensed matter physics communities, in a new category of anomalous chiral transport in quantum materials containing chiral fermions. A notable example is the Chiral Magnetic Effect (CME) [1-5] -the generation of an electric current J Q along the magnetic field B applied to the system, i.e. J Q = σ 5 B(1)