Bulletin of the American Physical Society
2011 Fall Meeting of the APS Division of Nuclear Physics
Volume 56, Number 12
Wednesday–Saturday, October 26–29, 2011; East Lansing, Michigan
Session DE: New Results in Fundamental Symmetries |
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Chair: Martin Cooper, Los Alamos National Laboratory Room: 103AB |
Thursday, October 27, 2011 10:30AM - 11:06AM |
DE.00001: New Results from the emiT Experiment: A Search for Time Reversal Invariance Violation in Neuron Decay Invited Speaker: Pieter Mumm The existence of charge-parity (CP) symmetry violation is necessary to explain the preponderance of matter over antimatter in the universe. Thus far, the observed CP violation can be entirely accounted for by a phase in the Cabbibo-Kobayashi- Maskawa matrix, however this phase is insufficient to account for the known baryon asymmetry in the context of Big Bang cosmology and there is good reason to search for CP and the related time-reversal violation in other systems. The emiT experiment tests time reversal symmetry in the $\beta$-decay of polarized free neutrons by searching for the T-odd, P-even triple correlation $D\vec{\sigma}_{n}\cdot \bf{{p_e}}\times\bf{{p_\nu}}$, where $\vec{\sigma}$ and $\bf{{p}}$ are the neutron spin and decay product momenta, respectively. The detection of this correlation above the small calculable effect from final state interactions would be a direct indication of time reversal symmetry violation. The $D$ coefficient is the most sensitive probe of the phase, $\phi_{AV}$, between the axial-vector (A) and vector (V) currents and is sensitive to scalar and tensor interactions that could arise due to beyond-Standard-Model physics. A 14-month run in 2002-2003 produced a sample of over 300 million proton- electron coincidence events. A blind analysis and extensive study of systematic effects has recently been completed with the result $D = (-0.96\pm1.89 (stat)\pm1.01(sys))\times10^{-4}$, representing the most sensitive test of time- reversal invariance in beta decay. Within the Standard Model, the result can be interpreted as a measure of the phase $\phi_{AV} = (180.013\pm0.028)^\circ$. [Preview Abstract] |
Thursday, October 27, 2011 11:06AM - 11:42AM |
DE.00002: Search for the lepton-flavour violating decay Mu -$>$ e + gamma -- Latest results from the MEG Experiment Invited Speaker: Peter-Raymond Kettle The first search for the lepton-flavour violating (LFV) decay Mu-$>$e + gamma, using cosmic rays, dates back some sixty years now. This, together with the diversity of such experiments that have followed, shows that the search for ``New Physics'' is not restricted to the high-energy frontier of TeV-scale accelerators but that the high-intensity, precision frontier can complement it. The MEG experiment at PSI is a LFV search experiment aiming at a sensitivity of O(10$^{-13})$ for the decay Mu-$>$e + gamma. By using one of the world's most intense surface muon beams, together with a liquid xenon detector of 900 litres and a gradient-field superconducting positron spectrometer, the two-body decay can be distinguished from the normal Michel and radiative muon decay processes. To resolve the dominant background process of accidental overlapping events, a detector with excellent spatial, temporal and energy resolution is required. The current status of the experiment as well as the latest results will be presented. [Preview Abstract] |
Thursday, October 27, 2011 11:42AM - 12:18PM |
DE.00003: Prospects for measuring CP violation in the Neutrino Sector Invited Speaker: Stephen Parke Recent indications that electron neutrino flavor content of the third neutrino mass eigenstate is large ($\theta_{13}$ large) provides the possibility that measuring CP violation in the Neutrino Sector is much easier than expected even a few months ago. I will review our understanding of the Neutrino Sector and how CP violation is a natural consequence of three flavor mixing, and how the next generation of Long Baseline Neutrino experiments have the real possibility of observing CP violation as well as determination of the mass ordering of the neutrinos. I will also review why we are interested in such CP violation and it's consequences for Leptogenesis which maybe the answer to the matter antimatter asymmetry observed in the current Universe. [Preview Abstract] |
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