Nucleon structure functions with domain wall fermions

We present a quenched lattice QCD calculation of the first few moments of the polarized and unpolarized structure functions of the nucleon. Our calculations are done using domain wall fermions and the DBW2 gauge action with inverse lattice spacing a(-1)approximate to 1.3 GeV, physical volume V approximate to(2.4 fm)(3), and light quark masses down to about 1/4 the strange quark mass (m(pi)approximate to 400 MeV). Values of the individual moments are found to be significantly larger than experiment, as in past lattice calculations, but interestingly the chiral symmetry of domain wall fermions allows for a precise determination of the ratio of the flavor nonsinglet momentum fraction to the helicity distribution, < x >(u-d)/< x >(Delta u-Delta d), which is in very good agreement with experiment. We discuss the implications of this result. Next, we show that the chiral symmetry of domain wall fermions is useful in eliminating mixing of power divergent lower dimensional operators with twist-3 operators. Finally, we compute the isovector tensor charge at renormalization scale mu=2 GeV in the (MS) over bar scheme, < 1 >(delta u-delta d)=1.192(30), where the error is the statistical error only.