143 research outputs found

### Light quark masses from quenched lattice QCD simulations with domain wall quarks

Values for the strange quark mass and average up/down mass have been obtained
from quenched lattice QCD simulations using the domain wall fermion action.
This discretization preserves the properties of flavor and chiral symmetry at
nonzero lattice spacing. Results are shown for two values of the lattice
spacing. The mass renormalization constant is computed nonperturbatively.Comment: To appear in the proceedings of DPF 2000, Columbus, OH, USA. Work
done as part of the RIKEN/BNL/Columbia Collaboration. (3 pages

### Light hadronic physics using domain wall fermions in quenched lattice QCD

In the past year domain wall fermion simulations have moved from exploratory
stages to the point where systematic effects can be studied with different
gauge couplings, volumes, and lengths in the fifth dimension. Results are
presented here for the chiral condensate, the light hadron spectrum, and the
strange quark mass. We focus especially on the pseudoscalar meson mass and show
that, in small volume, the correlators used to compute it can be contaminated
to different degrees by topological zero modes. In large volume a nonlinear
extrapolation to the chiral limit, e.g. as expected from quenched chiral
perturbation theory, is needed in order to have a consistent picture of low
energy chiral symmetry breaking effects.Comment: To appear in the proceedings of Lattice 2000 (spectrum), Bangalore,
India. Work done as part of the RIKEN/BNL/Columbia Collaboration. (4 pages) -
Reference adde

### Exploring Lattice Methods for Cold Fermionic Atoms

There has been a surge of experimental effort recently in cooling trapped
fermionic atoms to quantum degeneracy. By varying an external magnetic field,
interactions between atoms can be made arbitrarily strong. When the S wave
scattering length becomes comparable to and larger than the interparticle
spacing, standard mean field analysis breaks down. In this case the system
exhibits a type of universality, and J-W. Chen and D. B. Kaplan recently showed
how this system can be studied from first principles using lattice field
theory. This poster presents the first results of exploratory simulations. The
existence of a continuum limit is checked and the pairing condensate is studied
as a function of the external source strength over a range of temperatures.
Preliminary results show simulations can locate the critical temperature.Comment: Poster presented at Lattice2004(non-zero), Fermilab, 21-26 June 2004.
3 page

### Lattice QCD calculation of the ${{B}_{(s)}\to D_{(s)}^{*}\ell{\nu}}$ form factors at zero recoil and implications for ${|V_{cb}|}$

We present results of a lattice QCD calculation of $B\to D^*$ and $B_s\to
D_s^*$ axial vector matrix elements with both states at rest. These zero recoil
matrix elements provide the normalization necessary to infer a value for the
CKM matrix element $|V_{cb}|$ from experimental measurements of $\bar{B}^0\to
D^{*+}\ell^-\bar{\nu}$ and $\bar{B}^0_s\to D_s^{*+}\ell^-\bar{\nu}$ decay.
Results are derived from correlation functions computed with highly improved
staggered quarks (HISQ) for light, strange, and charm quark propagators, and
nonrelativistic QCD for the bottom quark propagator. The calculation of
correlation functions employs MILC Collaboration ensembles over a range of
three lattice spacings. These gauge field configurations include sea quark
effects of charm, strange, and equal-mass up and down quarks. We use ensembles
with physically light up and down quarks, as well as heavier values. Our main
results are $\mathcal{F}^{B\to D^*}(1)= 0.895\pm
0.010_{\mathrm{stat}}\pm{{0.024}_{\mathrm{sys}}}$ and $\mathcal{F}^{B_s\to
D_s^*}(1)= 0.883\pm 0.010_{\mathrm{stat}}\pm{0.028_{\mathrm{sys}}}$. We discuss
the consequences for $|V_{cb}|$ in light of recent investigations into the
extrapolation of experimental data to zero recoil.Comment: 23 pages. v3: Typos corrected. v2: Improved treatment of finite
volume effects. Small change to some results (but smaller than the quoted
uncertainties). Version accepted for publication in Phys. Rev.

### Lattice QCD Calculations with b Quarks: Status and Prospects

This talk gives an overview of how lattice QCD calculations are influencing
quark flavor physics. The first part of the talk focuses on the climb to higher
precision; the second part surveys views along less-trodden paths.Comment: 8 pages. Invited talk at the 13th International Conference on
B-Physics at Hadron Machines (BEAUTY 2011), 4-8 April 2011, Amsterdam, The
Netherlands, to appear as PoS(BEAUTY 2011)057. Version 2: updated discussion
of UTfit Collaboration's LQCD input

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