Momentum Distribution Critical Exponents for 1D Hubbard model in a Magnetic Field

Critical exponents at and for the momentum distribution function are studied for one-dimensional Hubbard model in the presence of magnetic field, using conformal field theory (CFT) approach. Exponents at and are reproduced. Results at is in contrast to earlier numerical prediction of 1, while at , the exponent is 49/8. The singularities at and appears to be weak and gradually degenerating into a smooth curve.