Abstract:
The construction of the first baryon operators for staggered lattice QCD exploited the taste symmetry to emulate physical quark flavor; contemporary 2+1 flavor simulations explicitly include three physical quark flavors and necessitate interpreting a valence sector with twelve quarks. After discussing expected features of the resulting baryon spectrum, I consider the spectra of operators transforming irreducibly under SU(3)xGTS, the direct product of flavor SU(3) and the geometrical time-slice group of the 1-flavor staggered theory. I then describe the construction of a set of maximally local baryon operators transforming irreducibly under SU(3)xGTS and enumerate this set. In principle, the operators listed here could be used to extract the masses of all the lightest spin-1/2 and spin-3/2 baryon resonances of staggered QCD. Using appropriate operators from this set in partially quenched simulations should allow for particularly clean 2+1 flavor calculations of the masses of the nucleon and the lightest decuplet.

Abstract:
In staggered QCD, many staggered baryons correspond to each physical state. Taste violations lift the continuum degeneracies of the baryons and introduce nonzero off-diagonal elements in the mass matrix. While presenting no problem of principle, these splittings and mixings complicate analyses of simulation results. However, in special cases operators with good SU(3) quantum numbers can be used to circumvent the splittings and mixings. I review what has been learned from staggered chiral perturbation theory, outline a program of attack for the amenable cases, and summarize the present status of work on the staggered chiral forms and operators with good SU(3)xGTS quantum numbers.

Abstract:
Although taste violations significantly affect the results of staggered calculations of pseudoscalar and heavy-light mesonic quantities, those entering staggered calculations of baryonic quantities have not been quantified. Here I develop staggered chiral perturbation theory in the light-quark baryon sector by mapping the Symanzik action into heavy baryon chiral perturbation theory. For 2+1 dynamical quark flavors, the masses of flavor-symmetric nucleons are calculated to third order in partially quenched and fully dynamical staggered chiral perturbation theory. To this order the expansion includes the leading chiral logarithms, which come from loops with virtual decuplet-like states, as well as terms the order of the cubed pion mass, which come from loops with virtual octet-like states. Taste violations enter through the meson propagators in loops and tree-level terms the order of the squared lattice spacing. The pattern of taste symmetry breaking and the resulting degeneracies and mixings are discussed in detail. The resulting chiral forms are appropriate to lattice results obtained with operators already in use and could be used to study the restoration of taste symmetry in the continuum limit. I assume that the fourth root of the fermion determinant can be incorporated in staggered chiral perturbation theory using the replica method.

Abstract:
Motivated by simulation results for octet and decuplet baryon masses using 2+1 flavors of light staggered quarks, we are incorporating staggered lattice artifacts into heavy baryon chiral perturbation theory, calculating the masses of various staggered baryons, and studying the connection between the staggered baryons of the chiral theory and the staggered baryons of simulations. We present order (m_q)^(3/2) loop contributions to the masses of several staggered nucleons and discuss interpolating fields that create these states.

Abstract:
We calculate the axial current decay constants of taste non-Goldstone pions and kaons in staggered chiral perturbation theory through next-to-leading order. The results are a simple generalization of the results for the taste Goldstone case. New low-energy couplings are limited to analytic corrections that vanish in the continuum limit; certain coefficients of the chiral logarithms are modified, but they contain no new couplings. We report results for quenched, fully dynamical, and partially quenched cases of interest in the chiral SU(3) and SU(2) theories.

Abstract:
We calculate the next-to-leading order axial current decay constants of taste non-Goldstone pions and kaons in staggered chiral perturbation theory. This is an extension of the taste Goldstone decay constants calculation to that of the non-Goldstone tastes. We present results for the partially quenched case in the SU(3) and SU(2) staggered chiral perturbation theories and discuss the difference between the taste Goldstone and non-Goldstone cases.

Abstract:
We present a review on recent progress in staggered chiral perturbation theory (SChPT). In the last decade, the scope of the application of SChPT has been extended beyond the level of calibration into the region of prediction with high precision. SChPT becomes an essential tool to do the data analysis reliably for physical observables calculated using improved staggered fermions. Here, we focus on the following examples: pion spectrum, pion decay constants, $\varepsilon_K$, and $\pi-\pi$ scattering amplitudes. In each subject, we review the recent progress and future prospects.

Abstract:
We present results of the masses of taste non-Goldstone $(F \ne \xi_5)$ pions and kaons calculated up to the next-to-leading order in the SU(3) staggered chiral perturbation theory (SChPT). The results can be used to fit data and to understand taste symmetry breaking effect quantitatively. The final expressions for the non-Goldstone masses contain 20 low energy constants unique to the non-Goldstone sector. We have calculated the several cases such as the full QCD, partially quenched QCD, and quenched QCD in the $N_f=1+1+1$ flavor and $N_f=2+1$ flavor cases in the SU(3) and SU(2) SChPT. In this paper, we present only the SU(3) part.

Abstract:
We present a review on recent progress in staggered chiral perturbation theory (SChPT). In the last decade, the scope of the application of SChPT has been extended beyond the level of calibration into the region of prediction with high precision. SChPT becomes an essential tool to do the data analysis reliably for physical observables calculated using improved staggered fermions. Here, we focus on the following examples: pion spectrum, pion decay constants, $\varepsilon_K$, and $\pi-\pi$ scattering amplitudes. In each subject, we review the recent progress and future prospects.

Abstract:
We present results for $\varepsilon_K$, the indirect CP violation parameter, calculated in the Standard Model using inputs from lattice QCD: the kaon bag parameter $\hat{B}_K$, and the CKM matrix element $V_{cb}$ from the axial current form factor for the exclusive decay $\bar{B}\to D^*\ell\bar{\nu}$ at zero-recoil. In addition, we take the coordinates of the unitarity triangle apex $(\bar{\rho},\bar{\eta})$ from the angle-only fit of the UTfit Collaboration and use $V_{us}$ to fix $\lambda$. In order to estimate the systematic error, we also use Wolfenstein parameters from the CKMfitter and UTfit. We find a $3.3(2)\sigma$ difference between $\varepsilon_K$ and experiment with exclusive $V_{cb}$. We report details of this preliminary result.