Tensor Charge of the Nucleon from QCD Sum Rules

The nucleon's tensor charges (isovector g^v_T = δu - δd and isoscalar g^s_T = δu + δd) are calculated using the QCD (quantum chromodynamics) sum rules in the presence of an external tensor field. By combining the mass sum rule of nucleon, we derive a simplified form for proton tensor charges, which gives g^v_T = 1.27 and g^s_T = 1.31, or δu = 1.29 and δd = 0.02 at the scale of nucleon mass, with an uncertainty about 20%.