Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session B2: Topics in Nuclear Physics |
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Sponsoring Units: DNP Chair: Susan Seestrom, Los Alamos National Laboratory Room: Hyatt Regency Jacksonville Riverfront Grand 1 |
Saturday, April 14, 2007 10:45AM - 11:21AM |
B2.00001: New Measurement of the Neutral Pion Life Time as a Precision Test of the Chiral Anomaly Invited Speaker: Symmetries and their spontaneous breaking effects play a fundamental role in our understanding of Nature. In particular, the three neutral light mesons, $\pi^0$, $\eta$ and $\eta^{\prime}$, contain fundamental information about chiral symmetry breaking, and their radiative decays are primarily defined by the chiral anomaly. Theoretical activities in this domain for the past several years resulted in a high precision (1\% level) prediction for the decay rate of the $\pi^0$ into two photons. The present experimental uncertainty of this decay rate, according to the Particle Data Group average, is an order of magnitude greater than the theoretical uncertainties. In the past several years, the PrimEx collaboration at Jefferson Lab has developed and performed a new experiment to measure the $\pi^0$ lifetime with high precision, using the small angle coherent photoproduction of $\pi^0$'s in the Coulomb field of a nucleus, {\it i.e.}, the Primakoff effect. The new level of experimental precision has been reached by implementing the new high intensity and resolution photon tagging facility in Hall B at Jefferson Lab and by developing a novel high resolution electromagnetic hybrid calorimeter (HYCAL). Two well known electromagnetic processes, the Compton scattering and the $e^+e^-$ pair production have been used to check the precision, as well as to control the long term stability of this experiment. The preliminary results of this new measurement at the few percent level will be presented and compared with the recent predictions of chiral perturbation theory. [Preview Abstract] |
Saturday, April 14, 2007 11:21AM - 11:57AM |
B2.00002: The Day-Night Effect in SNO: Beyond the Solar Neutrino Problem Invited Speaker: Results from the Sudbury Neutrino Observatory (SNO) experiment have demonstrated that electron neutrinos produced in the solar interior change flavor prior to reaching the earth, thus resolving the long-standing ``Solar Neutrino Problem.'' Far from being the end of the story, these and other recent neutrino physics results have opened up a rich field of fundamental questions to be probed by current and future experiments. The day-night asymmetry measurement performed during the second phase of the SNO experiment will be described, emphasizing the role that solar neutrino experiments play in exploring fundamental neutrino physics. [Preview Abstract] |
Saturday, April 14, 2007 11:57AM - 12:33PM |
B2.00003: Heavy Quark Energy Loss in a Strongly Interacting Quark Gluon Plasma Invited Speaker: One of the fundamental predictions of QCD is that, at extremely high energy densities, a new form of matter may be formed. This state of matter, consisting of interacting quarks, antiquarks and gluons, is called the Quark-Gluon Plasma (QGP). The QGP is predicted to exist at extreme values of temperature and/or baryon number density. Today, UltraRelativistic Heavy Ion Colliders (RHIC and LHC) are constructed with an aim to form, observe and understand the properties of this new state of matter. Heavy quark production and attenuation patterns provide unique probes of QCD matter. In this talk, I will review the current state of theory and experiment in the heavy quark tomography. I will present the radiative energy loss formalism that we developed, as well as the heavy flavor suppression results obtained from this energy loss. I will show that radiative energy loss alone cannot explain the currently available indirect heavy flavor measurements at RHIC. However, we have recently further improved the heavy quark energy loss formalism by including important collisional energy loss effects, which were previously considered to be negligible. I will show that the inclusion of collisional energy loss in the jet quenching significantly improves the agreement with the available heavy flavor data. We expect that the developed theoretical methods and the obtained predictions will significantly contribute toward understanding of the RHIC and LHC experimental results. This work is supported by the U.S. Department of Energy under Grants DE-FG02-93ER40764 and DE-FG02-01ER41190. [Preview Abstract] |
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