  We present the calculation of matrix elements of iso-vector scalar, axial and
tensor charges between a neutron and a proton state on dynamical $N_f=2+1+1$
HISQ configurations generated by the MILC Collaboration using valence clover
fermions. These matrix elements are needed to probe novel scalar and tensor
interactions in neutron beta-decay that can arise in extensions to the Standard
Model at the TeV scale. Results are presented at one value of the lattice
spacing, $a=0.12$ fm, and two values of light quarks corresponding to
$M_\pi=310$ and $220$ MeV. We discuss two sources of systematic errors,
contribution of excited states to these matrix elements and the renormalization
constants, and the efficacy of methods used to control them.
