1751350
Light hadron spectrum in three-flavor QCD with O(a)-improved Wilson quark action
We report on a calculation of the light hadron spectrum and quark masses in three-flavor dynamical QCD using the non-perturbatively O(a)-improved Wilson quark action and a renormalization-group improved gauge action. Simulations are carried out on a 163 × 32 lattice at β = 1.9, where a−1 ≅ 2 GeV, with 6 ud quark masses corresponding to mπmϱ ≅ 0.64–0.77 and 2 s quark masses close to the physical value. We observe that the inclusion of dynamical strange quark brings the lattice QCD meson spectrum to good agreement with experiment. Dynamical strange quarks also lead to a reduction of the uds quark masses by about 15%.
117535752
Improving chiral property of domain-wall fermions by reweighting method
The reweighting method is applied to improve the chiral property of domain-wall fermions. One way to achieve this is to enlarge L{sub s}, the size of fifth dimension, which controls the size of the induced chiral symmetry breaking. While this is a type of reweighting method for shifting the action parameter, it seems non-trivial since this reweighting means change of the five dimensional lattice volume. In this report, we address issues in this direction of reweighting and evaluate its effectiveness.
119237422
One-loop operator matching in the static heavy and domain-wall light quark system with O(a) improvement
We discuss perturbative O(g2a) matching with static heavy quarks and domain-wall light quarks for lattice operators relevant to B-meson decays and $ {B^0} - {\bar{B}^0} $ mixing. The chiral symmetry of the light domain-wall quarks does not prohibit operator mixing at O(a) for these operators. The O(a) corrections to physical quantities are non-negligible and must be included to obtain high-precision simulation results for CKM physics. We provide results using plaquette, Symanzik, Iwasaki and DBW2 gluon actions and applying APE, HYP1 and HYP2 link-smearing for the static quark action.
119107424
Neutral $B$ meson mixings and $B$ meson decay constants with static heavy and domain-wall light quarks
Neutral $B$ meson mixing matrix elements and $B$ meson decay constants are calculated. Static approximation is used for $b$ quark and domain-wall fermion formalism is employed for light quarks. The calculations are carried out on $2+1$ flavor dynamical ensembles generated by RBC/UKQCD Collaborations with lattice spacings $0.086$fm ($a^{-1}\sim 2.3$GeV) and $0.11$fm ($1.7$GeV), and a fixed physical spatial volume of about $(2.7{\rm fm})^3$. In the static quark action, link-smearings are used to improve the signal-to-noise ratio. We employ two kinds of link-smearings, HYP1 and HYP2, and their results are combined in taking the continuum limit. For the matching between the lattice and the continuum theory, one-loop perturbative $O(a)$ improvements are made to reduce discretization errors. As the most important quantity of this work, we obtain SU(3) breaking ratio $\xi=1.208(60)$, where the error includes statistical and systematic one. (Uncertainty from infinite $b$ quark mass is not included.) We also find other neutral $B$ meson mixing quantities $f_B\sqrt{\hat{B}_B}=240(22)$MeV, $f_{B_s}\sqrt{\hat{B}_{B_s}}=290(22)$MeV, $\hat{B}_B=1.17(22)$, $\hat{B}_{B_s}=1.22(13)$ and $B_{B_s}/B_B=1.028(74)$, $B$ meson decay constants $f_B=219(17)$MeV, $f_{B_s}=264(19)$MeV and $f_{B_s}/f_B=1.193(41)$, in the static limit of $b$ quark, which do not include infinite $b$ quark mass uncertainty.
17179550
Quenched Scaling Study of Charm and Bottom Systems with a Relativistic Heavy Quark Action
CP-PACS Collaborations: Y. Kuramashi∗a,b †, S. Aokib,c, O. Bärb, K.-I. Ishikawag, T. Ishikawaa, N. Ishizukaa,b, Y. Iwasakib, K. Kanayab, T. Kanekoe, f , M. Okawag, Y. Taniguchia,b, N. Tsutsuie, A. Ukawaa,b, N. Yamadae and T. Yoshiéa,b a Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan b Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan c Riken BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973, USA d Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582, Japan e High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan f School of High Energy Accelerator Science, The Graduate University for Advanced Studies (Sokendai), Tsukuba 305-0801, Japan g Department of Physics, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
117986111
An estimate of the eta and eta-prime meson masses in Nf=2+1 lattice QCD
Masses of the eta and eta-prime mesons are estimated in Nf=2+1 lattice QCD with the non-perturbatively O(a) improved Wilson quark action and the Iwasaki RG-improved gluon action, using CP-PACS/JLQCD configurations on a 16^3 x 32 lattice at beta=1.83 (lattice spacing is 0.122 fm). We apply a stochastic noise estimator technique combined with smearing method to evaluate correlators among flavor SU(2) singlet pseudoscalar operators and strange pseudoscalar operators for 10 combinations of up/down and strange quark masses. The correlator matrix is then diagonalized to identify signals for mass eigenstates. Masses of the ground state and the first excited state extrapolated to the physical point are m_eta= 0.545(16) GeV and m_eta-prime= 0.871(46) GeV, being close to the experimental values of the eta and eta-prime masses.
14116211
Extrapolation Algorithms for Infrared Divergent Integrals
This paper describes applications of extrapolation for the computation of coefficients in an expansion of infrared divergent integrals. An extrapolation procedure is performed with respect to a parameter introduced by dimensional regularization. While this treats typical IR singularities at the boundaries of the integration domain, special care needs to be taken in cases where the integrand is singular in the interior of the domain as well as on the boundaries. A double extrapolation is devised for a class of massless vertex integrals. Quadruple precision results are presented, demonstrating high accuracy. The computations are supported by the use of general adaptive integration programs from the QUADPACK package, in iterated integrations with highly singular integrand functions.
124047947
Recursive box and vertex integrations for the one-loop hexagon reduction in the physical region
We provide a technique which makes an efficient numerical evaluation feasible for the ndimensional triangle functions and n+2-dimensional box functions, resulting from a reduction of the one-loop hexagon integral. At the level of the three- and four-point functions, a dimensional recursion of an adaptive numerical integration with extrapolation is effective for the corresponding low-dimensional integrals, even to integrate through threshold singularities present in cases of physical kinematics. An important reason for the reduction to these levels (in lieu of resorting to analytical formulas at a higher level), is that infrared divergences are made transparent so they can be separated. We give results for various sets of kinematic configurations, showing the feasibility and accuracy of the approach. Thus a bridge is provided between the computations of the reduction and direct numerical integration at a lower level.
120133529
Two-body and three-body decays of charginos in one-loop order in the MSSM
We present the renormalization scheme used in and the characteristic features of GRACE/SUSY-loop, the package of the program for the automatic calculation of the minimal supersymmetric standard model processes including one-loop order corrections. The two-body and three-body decay widths of charginos in one-loop order evaluated by GRACE/SUSY-loop are shown.
4932897
A development of an accelerator board dedicated for multi-precision arithmetic operations and its application to Feynman loop integrals II.
Evaluation of a wide variety of Feynman diagrams with multi-loop integrals and physical parameters and its comparison with high energy experiments are expected to investigate new physics beyond the Standard Model. We have been developing a direct computation method of multi-loop integrals of Feynman diagrams. One of features of our method is that we adopt the double exponential rule for numerical integrations which enables us to evaluate loop integrals with boundary singularities. Another feature is that in order to accelerate the numerical integrations with multi-precision calculations, we develop an accelerator system with Field Programmable Gate Array boards on which processing elements with dedicated logic for quadruple/hexuple/octuple precision arithmetic operations are implemented. In addition, we also develop a programming interface designed for easy use of the system. The development is continued for practical use of the system. We present the current development of our system, and the numerical results of higher-loop diagrams performed using our system.
118066030
Hybrid Parallel Computation of Integration in GRACE
With an integrated software package {\tt GRACE}, it is possible to generate Feynman diagrams, calculate the total cross section and generate physics events automatically. We outline the hybrid method of parallel computation of the multi-dimensional integration of {\tt GRACE}. We used {\tt MPI} (Message Passing Interface) as the parallel library and, to improve the performance we embedded the mechanism of the dynamic load balancing. The reduction rate of the practical execution time was studied.