Atomic parity violation, leptoquarks, and contact interactions

The recent measurement of atomic parity violation in cesium atoms shows a 2.3 sigma deviation from the standard model prediction. We show that such an effect can be explained by four-fermion contact interactions with specific chiralities or by scalar leptoquarks which couple to the left-handed quarks. For a coupling of electromagnetic strength, the leptoquark mass is inferred to be 1.1 to 1.3 TeV. We also show that these solutions are consistent with all other low-energy and high-energy neutral-current data. (C) 2000 Elsevier Science B.V. All rights reserved.