College Park, Maryland      June 6 - 10 , 2004

M4-B4 (4:45 PM): Search for New Physics from Neutron Beta-Decay

V. Gudkov (Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208)

New Spallation Neutron Source at the Oak Ridge National Laboratory will provide unique opportunity to increase significantly the accuracy in measurements of parameters of neutron beta-decay. It will improve the precision of the value of axial-vector coupling constant, which is in high demand for neutrino physics, astrophysics, and other applications of the theory of weak interactions. Precise measurements of neutron decay will lead to the possibility to obtain the Cabibbo-Kobayashi-Maskawa matrix element in nuclear model independent way. The value of this matrix element dominates the unitarity condition of the Standard Model which is very sensitive to the possible manifestations of new physics. Measurements of angular correlations can clarify problems related to the possibility of existence of exotic interactions and violations of fundamental symmetries.

For precise determination of the fundamental constants and for an unambiguous search for new physics in neutron decay experiments, the careful analysis of all possible corrections to neutron decay process should be done. This talk presents analysis of these corrections: including radiative corrections calculated using both the standard approach [1] and the effective field theory [2]. The possibility to obtain parameters of neutron beta decay in model independent way is discussed (see, for example [3]). The given analysis can be used for the estimation of the sensitivity of neutron decay process to new physics.

1. A. Sirlin, ”General Properties of the Electromagnetic Corrections to the Beta Decay of a Physical Nucleon”, Phys. Rev. 164 (1967) 1767.
2. S. Ando, H. W. Fearing, V. Gudkov, K. Kubodera, F. Myhrer, S. Nakamura and T. Sato, “Neutron beta decay in effective field theory”, arXiv:nucl-th/0402100 (2004).
3. V. Gudkov, “New generation of neutron decay experiments”, J. of Neutron Research (2004) in press.

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