1202.1570 (Jon A. Bailey et al.)

Kaon mixing matrix elements from beyond-the-Standard-Model operators in
staggered chiral perturbation theory    [PDF]

Jon A. Bailey, Hyung-Jin Kim, Weonjong Lee, Stephen R. Sharpe

Models of new physics induce K-Kbar mixing operators having Dirac structures
other than the "left-left" form of the Standard Model. We calculate the
functional form of the corresponding B-parameters at next-to-leading order in
both SU(3) and SU(2) staggered chiral perturbation theory (SChPT). Numerical
results for these matrix elements are being generated using improved staggered
fermions; our results can be used to extrapolate these matrix elements to the
physical light and strange quark masses. The SU(3) SChPT results turn out to be
much simpler than that for the Standard Model B_K operator, due to the absence
of chiral suppression in the new operators. The SU(2) SChPT result is of
similar simplicity to that for B_K. In fact, in the latter case, the chiral
logarithms for two of the new B-parameters are identical to those for B_K,
while those for the other two new B-parameters are of opposite sign. In
addition to providing results for the 2+1 flavor theory in SU(3) SChPT and the
1+1+1 flavor theory in SU(2) SChPT, we present the corresponding continuum
partially quenched results, as these are not available in the literature.

View original: http://arxiv.org/abs/1202.1570