Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session Q9: Mini-Symposium on Local Parity Violation and the Chiral Magnetic Effect in the QGP: Status and Prospects |
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Sponsoring Units: DNP Chair: Agnes Mocsy, Pratt Institute Room: Governor's Square 11 |
Monday, April 15, 2013 10:45AM - 11:21AM |
Q9.00001: LPV and Chiral Magnetic Effect: status and open questions Invited Speaker: Adam Bzdak I provide an analysis of theoretical and phenomenological searches for local parity violation manifested through the Chiral Magnetic Effect. I discuss the relevant correlation functions used for the measurements, and argue that the present experimental evidence for the Chiral Magnetic Effect is rather ambiguous. I further discuss various background contributions due to conventional physics, which need to be understood quantitatively in order to draw a definitive conclusion about the existence of local parity violation in heavy ion collisions. Finally, I propose a simple observable which can distinguish between the Chiral Magnetic Effect and various elliptic-flow-induced effects. [Preview Abstract] |
Monday, April 15, 2013 11:21AM - 11:33AM |
Q9.00002: Azimuthally fluctuating magnetic field and its impact on observables in heavy-ion collisions John Bloczynski, Xu-Guang Huang, Xilin Zhang, Jinfeng Liao The heavy-ion collisions can produce extremely strong transient magnetic and electric fields that may generate interesting effects such as the Chiral Magnetic Effect. An important missing link is the orientation of the fluctuating E and B fields with respect to the fluctuating matter geometry in the same event. In this presentation, we report for the first time the azimuthal fluctuation of these fields and their correlations with the also fluctuating matter geometry (characterized by the participant plane harmonics) using event-by-event simulations. A sizable suppression of the angular correlations between the magnetic field and the $2nd$ and $4th$ harmonic participant planes is found in very central and very peripheral collisions, while the magnitudes of these correlations peak around impact parameter $b\sim8-10\rm fm$ for RHIC collisions. This can lead to notable impacts on a number of observables related to various magnetic field induced effects, and our finding suggests that the optimal event class for measuring them should be that corresponding to $b\sim8-10$. we also propose new new measurements that can help fully mapping out the azimuthal correlation patterns of charged particles. [J. Bloczynski, X. Huang, X. Zhang, J.Liao, sarXiv:1209.6594, Phys. Lett. B in press.] [Preview Abstract] |
Monday, April 15, 2013 11:33AM - 11:45AM |
Q9.00003: Berry curvature and 4-dimensional monopole in relativistic chiral kinetic equation Jiunn-Wei Chen We derive a relativistic chiral kinetic equation with manifest Lorentz covariance and a 4-dimensional Euclidean Berry monopole. The theory is based on Wigner functions of spin-1/2 massless fermions in a constant electromagnetic background. By integrating out the $p_0$-component of the 4-momentum p, the previous 3-dimensional results derived (without vorticity) from the Hamiltonian approach is reproduced. The phase space continuity equation has a source term proportional to the product of the vorticity and electric field while the axial anomaly arises from the flux of the monopole. This makes the chiral magnetic effect, vorticity, chiral anomaly, Berry phase, and the monopole can all be described in a unified way by Wigner functions. [Preview Abstract] |
Monday, April 15, 2013 11:45AM - 11:57AM |
Q9.00004: Estimation of the background effects in the chiral magnetic effect measurements using charge-dependent correlations relative to the fourth harmonic event plane Jocelyn Mlynarz The measurements of the charge-dependent correlations in a heavy-ion collisions allow to experimentally probe the Chiral Magnetic Effect (CME). While being sensitive to the CME effects, charge dependent correlations are also susceptible to potentially large background contributions which may e.g. originate from effects of the local charge conservation or in general due to any particle production from clusters modulated by the anisotropic flow. In this talk, we present results from charge-dependent correlations with respect to the second and fourth harmonic event planes measured in Pb+Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV at the LHC using data from the ALICE detector. Correlation with respect to the 2nd harmonic event plane, $ |
Monday, April 15, 2013 11:57AM - 12:09PM |
Q9.00005: Magnetic field in heavy-ion collisions Vladimir Skokov The key ingredient for predictions of the Chiral Magnetic Effect is a high magnetic field. I will discuss the properties of a magnetic field in heavy-ion collisions, especially, its lifetime and influence of finite electric and chiral conductivities. I will present numerical results for realistic values of the parameters. I will shortly discuss how the magnetic field manifests itself in photon production. [Preview Abstract] |
Monday, April 15, 2013 12:09PM - 12:21PM |
Q9.00006: Azimuthal anisotropy in central U+U collisions at STAR Hui Wang The azimuthal anisotropy of particle production is commonly used in high-energy nuclear collisions to study the early evolution of the expanding system. The prolate shape of uranium nuclei provides the possibility to study how the initial geometry of the nuclei affects the azimuthal distributions. This allows one to study a variety of topics such as local parity violation, path length dependence of jet quenching, and particle production in heavy ion collisions. In this talk,the two-particle cumulant, $v_2$, from central U+U collisions at $\sqrt{s_{NN}}=$ 193 GeV and central Au+Au collisions at $\sqrt{s_{NN}}=$ 200 GeV for inclusive charged hadrons will be presented. The STAR Zero Degree Calorimeters were used to select the most central collisions. Differences were observed between the multiplicity dependence of $v_2$ for central Au+Au and U+U collisions. The observed $v_2$ slope results were compared to Glauber model predictions and it was seen that this model cannot explain the present results on the multiplicity dependence of $v_2$ in central collisions. [Preview Abstract] |
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