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تسجيل مستخدم جديدThe Qweak Experiment: A Search for New Physics at the TeV Scale via a Measurement of the Protons Weak Charge
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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 protons weak charge, $Q_W =1 - 4sin^2theta_W$. 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 protons 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.
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From a distance, the protons weak charge is seen through the distorting effects of clouds of virtual particles. The effective weak charge can be calculated by starting with the measured weak coupling at the Z-pole and running the coupling to lower en
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