arXiv subjects

Christopher Aubin

Publications and source records attributed to Christopher Aubin.

22 records · Page 2Linked to original sources

arXiv2011

Chiral expansion for lattice computations of B^{+} to D^{0}K^{+} (π^{+}) and B^{+} to Dbar^{0} K^{+} (π^{+}) amplitudes

In this work, we suggest that hard-pion chiral perturbation theory may be applicable to the real parts of nonleptonic B^{+} to D^{0}P^{+} and B^{+} to Dbar^{0}P^{+} (P=K,pi) decay amplitudes. These amplitudes play an important role in the extraction of the angle gamma in the b-d unitarity triangle of the CKM matrix, and their real parts can be computed using lattice QCD. We construct the leading-order operator in the chiral expansion for these nonleptonic decays, and discuss the generic features of the next-to-leading-order terms.

hep-lat↗

arXiv2008

Light pseudoscalar meson masses and decay constants from mixed action lattice QCD

We calculate the light pseudoscalar decay constants, f_pi and f_K, and their ratio using domain wall valence quarks and 2+1 flavors of dynamical staggered quarks. Use of the MILC gauge configurations allows us to simulate at several sea quark masses and spatial volumes, and with two lattice spacings. We study how well our numerical lattice data for light decay constants and meson masses is described by next-to-leading order SU(3) mixed action chiral perturbation theory and explain our strategy for the chiral and continuum extrapolation. Combining our result for f_K/f_pi with experimental measurements of pion and kaon leptonic decays allows a model-independent determination of |V_us|/|V_ud|; we find a preliminary value of |V_us|/|V_ud| = 0.2315(45)(7).

hep-lat↗

arXiv2007

The kaon B-parameter from unquenched mixed action lattice QCD

We present a preliminary calculation of B_K using domain-wall valence quarks and 2+1 flavors of improved staggered sea quarks. Both the size of the residual quark mass, which measures the amount of chiral symmetry breaking, and of the mixed meson splitting Delta_mix, a measure of taste-symmetry breaking, show that discretization effects are under control in our mixed action lattice simulations. We show preliminary data for pseudoscalar meson masses, decay constants and B_K. We discuss general issues associated with the chiral extrapolation of lattice data, and, as an example, present a preliminary chiral and continuum extrapolation of f_pi. The quality of our data shows that the good chiral properties of domain-wall quarks, in combination with the light sea quark masses and multiple lattice spacings available with the MILC staggered configurations, will allow for a precise determination of B_K.

hep-lat↗

arXiv2005

Lowest Order Hadronic Contribution to the Muon g-2

We present the most recent lattice results for the lowest-order hadronic contribution to the muon anomalous magnetic moment using 2+1 flavor improved staggered fermions. A precise fit to the low-q^2 region of the vacuum polarization is necessary to accurately extract the muon g-2. To obtain this fit, we use staggered chiral perturbation theory with the inclusion of the vector particles as resonances, to evaluate the vacuum polarization. We discuss the preliminary fit results and attendant systematic uncertainties, paying particular attention to the relative contributions of the pions and vector mesons.

hep-lat↗