Tuesday, February 7, 2012

1202.1255 (D. S. Armstrong et al.)

The Qweak Experiment: A Search for New Physics at the TeV Scale via a
Measurement of the Proton's Weak Charge
   [PDF]

D. S. Armstrong, A. Asaturyan, T. Averett, J. Benesch, J. Birchall, P. Bosted, A. Bruell, C. L. Capuano, G. Cates, C. Carrigee, R. D. Carlini, S. Chattopadhyay, S. Covrig, C. A. Davis, K. Dow, J. Dunne, D. Dutta, R. Ent, J. Erler, W. Falk, H. Fenker, J. M. Finn, T. A. Forest, W. Franklin, D. Gaskell, M. Gericke, J. Grames, K. Grimm, F. W. Hersman, D. Higinbotham, M. Holtrop, J. R. Hoskins, K. Johnston, E. Ihloff, M. Jones, R. Jones, K. Joo, J. Kelsey, C. Keppel, M. Khol, P. King, E. Korkmaz, S. Kowalski, J. Leacock, J. P. Leckey, L. Lee, A. Lung, D. Mack, S. Majewski, J. Mammei, J. Martin, D. Meekins, A. Micherdzinska, A. Mkrtchyan, H. Mkrtchyan, N. Morgan, K. E. Myers, A. Narayan, A. K. Opper, J. Pan, S. A. Page, K. Paschke, M. Pitt, M. Poelker, Y. Prok, W. D. Ramsay, M. Ramsey-Musolf, J. Roche, N. Simicevic, G. Smith, T. Smith, P. Souder, D. Spayde, B. E. Stokes, R. Suleiman, V. Tadevosyan, E. Tsentalovich, W. T. H. van Oers, W. Vulcan, P. Wang, S. Wells, S. A. Wood, S. Yang, R. Young, H. Zhu, C. Zorn
We propose a new precision measurement of parity-violating electron
scattering on the proton at very low Q^2 and forward angles to challenge
predictions of the Standard Model and search for new physics. A unique
opportunity exists to carry out the first precision measurement of the proton's
weak charge, $Q_W =1 - 4\sin^2\theta_W$. A 2200 hour measurement of the parity
violating asymmetry in elastic ep scattering at Q^2=0.03 (GeV/c)^2 employing
180 $\mu$A of 85% polarized beam on a 35 cm liquid Hydrogen target will
determine the proton's weak charge with approximately 4% combined statistical
and systematic errors. The Standard Model makes a firm prediction of $Q_W$,
based on the running of the weak mixing angle from the Z0 pole down to low
energies, corresponding to a 10 sigma effect in this experiment.
View original: http://arxiv.org/abs/1202.1255

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