32nd International Symposium on Lattice Field Theory (Lattice 2014)

Session

Weak Decays and Matrix Elements

6

23 Jun 2014, 16:30

Columbia University

Conveners

Weak Decays and Matrix Elements: Parallel 2G

• Andreas Juettner (University of Southampton)

Weak Decays and Matrix Elements: Parallel 5G

• Heechang Na (University of Utah)

Weak Decays and Matrix Elements: Parallel 6G

• Aida El-Khadra (University of Illinois)

Weak Decays and Matrix Elements: Parallel 9B

• Oliver Witzel (Boston University)

243. Calculation of $K\to \pi \pi$ decay amplitudes with improved Wilson fermion in 2+1 flavor lattice QCD

Dr Naruhito Ishizuka (University of Tsukuba)

23/06/2014, 16:30

Weak Decays and Matrix Elements

Talk

We presnet our results of the $K\to \pi \pi$ decay amplitudes for both the $\mathrm{\Delta }I=1/2$ and $3/2$ channels. Calculations are carried out with $N_f=2+1$ gauge configurations previously generated by the PACS-CS Collaboration with the Iwasaki gauge action and nonperturbatively $O(a)$-improved Wilson fermion at $a=0.091\mathrm{f}\mathrm{m}$ and $m_{\pi }=280\mathrm{M}\mathrm{e}\mathrm{V}$ on a ${32}^3\times 64$ ($La=2.9...

380. Lattice Measurement of the Delta I=1/2 Contribution to Standard Model Direct CP-Violation in K->pi pi Decays at Physical Kinematics: Part I

Dr Christopher Kelly (Brookhaven National Laboratory)

23/06/2014, 16:50

Weak Decays and Matrix Elements

Talk

The RBC & UKQCD collaborations have recently published lattice results for the K->pi pi decay amplitude in the I=2 channel, A_2, and improved results will be presented at this conference. In this presentation we discuss the determination of the I=0 channel amplitude, A_0. Combining this with A_2 provides epsilon', the measure of direct CP-violation in the Standard Model. In part I we provide...

388. Lattice Measurement of the Delta I=1/2 Contribution to Standard Model Direct CP-Violation in K->pi pi Decays at Physical Kinematics: Part II

Mr Daiqian Zhang (Columbia University)

23/06/2014, 17:10

Weak Decays and Matrix Elements

Talk

In continuation of part I, I will discuss our use of all-to-all propagators in order to construct pi-pi operators with reduced coupling to the vacuum, which helps to reduce the noise in the K->pipi(I=0) decay amplitude. I will also present preliminary results for the pipi(I=0) phase shift, decay amplitude A_0, both with physical kinematics. The precise value of A_0, once computed, will provide...

334. Rare kaon decays from lattice QCD

Dr Xu Feng (Columbia University)

23/06/2014, 17:30

Weak Decays and Matrix Elements

Talk

The rare kaon decays, $K\to pinun{u}_{b}ar$ and $K\to pi{l}^{+}{l}^{-}$, serve as ideal probes for the observation of New Physics (NP) effects. To isolate the NP contributions successfully, one needs to control the errors for Standard Model prediction from both short- and long-distance contributions. RBC-UKQCD collaborations have performed a successful exploratory study on the calculation of the...

359. Kl - Ks mass difference computed with a 171 MeV pion mass

Mr Ziyuan Bai (Columbia University in the city of New York)

23/06/2014, 17:50

Weak Decays and Matrix Elements

Talk

In this work, I used a ${32}^3\times 64\times 32$, 2+1 flavor domain wall lattice with Iwasaki+DSDR gauge action. The pion mass is 171 MeV and the kaon mass is 492 MeV. We implement the Glashow-Iliopoulos-Maiani (GIM) cancellation using charm quark masses of 750 MeV and 592 MeV. This is an intermediate calculation, in that we are using both a coarse lattice spacing (1/a = 1.37GeV) so we...

409. The Kaon Semileptonic Form Factor from Domain Wall QCD at the Physical Point

Mr David Murphy (Columbia University)

23/06/2014, 18:10

Weak Decays and Matrix Elements

Talk

We present an update on the RBC/UKQCD collaboration’s calculation of the kaon semileptonic form factor at zero momentum transfer, $f_{+}^{K\pi }(0)$. This calculation utilizes two new $N_f=2+1$ M\"{o}bius Domain Wall Fermion ensembles which allow us to simulate QCD directly at physical pion mass for the first time. Together with our previous results we now have a complete set of...

122. The scalar B meson in the static limit of HQET

Mr Antoine Gérardin (LPT)

25/06/2014, 09:00

Weak Decays and Matrix Elements

Talk

I will present results on the scalar B meson ($B_0^{\ast }$) sector using $N_f=2$ $\mathcal{O}(a)$-improved Wilson-Clover fermions and the Heavy Quark Effective Field theory at the static limit to describe the b-quark. Since the scalar B meson lies near the B $\pi$ threshold for our simulations set-up, we have implemented meson-meson as well as quark-antiquarks interpolating fields to disentangle...

416. B meson decay constants and Delta B=2 matrix elements with static heavy and doma in-wall light quarks

Dr Tomomi Ishikawa (RIKEN BNL Research Center)

25/06/2014, 09:20

Weak Decays and Matrix Elements

Talk

Neutral B meson mixing matrix elements and B meson decay constants are calculated. Static approximation is used for b quark and domain-wall fermion is employed for light quarks. The calculations are carried out on Nf=2+1 dynamical ensembles with lattice spacings of 0.086fm and 0.11fm, and a fixed physical spatial volume of about (2.7fm)^3, generated by RBC/UKQCD Collaborations. We employ two...

364. B-physics with domain-wall light quarks and nonperturbatively tuned relativistic b-quarks

Oliver Witzel (Boston University)

25/06/2014, 09:40

Weak Decays and Matrix Elements

Talk

We compute B-meson decay-constants and neutral B-meson mixing using relativistic b-quarks and domain-wall light quarks. We present results for fB, fBs, and their ratio including a complete systematic error budget from an analysis of five sea-quark ensembles with pion masses as light as ~290 MeV and two lattice spacings of a~0.11 and 0.08 fm. We are currently adding data at the physical pion...

212. Neutral B-meson mixing parameters in and beyond the SM with 2+1 flavor lattice QCD

Aida El-Khadra (University of Illinois)

25/06/2014, 10:00

Weak Decays and Matrix Elements

Talk

We present the status of our calculation of the hadronic matrix elements for neutral B-meson mixing with asqtad sea and valence light quarks and using the Wilson clover action with the Fermilab interpretation for the b quark. We calculate the matrix elements of all five local operators that contribute to neutral B-meson mixing both in and beyond the SM. Our analysis includes MILC asqtad...

188. Charm physics with Moebius Domain Wall Fermions

Mr Justus Tobias Tsang (University of Southampton)

25/06/2014, 11:10

Weak Decays and Matrix Elements

Talk

We study the feasibility of using a novel discretisation (Moebius) to directly simulate charm physics within the Domain Wall formalism. We then present results for a range of physical quantities including meson masses as well as decay constants and the dispersion relation of heavy-heavy (eta_c) and heavy-strange (D_s) pseudoscalar mesons. Four extensive sets of tree-level Symanzik pure gauge...

337. Charm physics with physical light and strange quarks using domain wall fermions

Dr Andreas Juettner (University of Southampton)

25/06/2014, 11:30

Weak Decays and Matrix Elements

Talk

This talk will provide an overview of RBC/UKQCD's charm project on their 2+1 flavour physical point ensembles using Moebius Domain Wall Fermions for the light as well as for the charm quark. After a brief motivation of DWF as a suitable heavy quark discretisation we will show first results for masses and matrix elements.

226. Scaling study of an improved fermion action on quenched lattices

Mr Yong-Gwi Cho (University of tsukuba)

25/06/2014, 11:50

Weak Decays and Matrix Elements

Talk

We present scaling studies for heavy-quark observables calculated with an O(a^2)-improved fermion action on tree-level Symanzik improved gauge configurations. Lattices of 1/a = 2.0-3.7 GeV with an equal physical volume ~1.6 fm are used. The results are compared with the standard domain-wall and naive Wilson fermions.

195. Charmed and strange pseudoscalar meson decay constants from HISQ simulations

Mr Javad Komijani (Washington University in St. Louis)

25/06/2014, 12:10

Weak Decays and Matrix Elements

Talk

We present final results for decay constants of charmed and strange pseudoscalar mesons, calculated on MILC ensembles with four dynamical quarks. The HISQ action is used for both the valence and sea quarks. A straightforward analysis on the ensembles with physical quark masses, which avoids the need for chiral perturbation theory, is performed first. We report the resulting values for...

362. Leptonic B and D decay constants with 2+1 flavor asqtad fermions

Prof. Ethan Neil (University of Colorado, Boulder)

25/06/2014, 12:30

Weak Decays and Matrix Elements

Talk

We present the status of our updated D and B meson decay-constant analysis, based on the MILC Nf=2+1 asqtad gauge ensembles. Heavy quarks are incorporated using the Wilson clover action with the Fermilab interpretation. This analysis includes ensembles at five lattice spacings from a=0.045 to 0.15 fm, and light-quark sea masses down to 1/20 of the strange-quark mass. A complete...

376. Matrix elements for D-meson mixing from 2+1 lattice QCD

Chia Cheng Chang (University of Illinois)

25/06/2014, 12:50

Weak Decays and Matrix Elements

Talk

We present the status of our calculation of the D-meson mixing hadronic matrix elements for all five short-distance operators. We use the $N_f=2+1$ asqtad gauge field ensembles generated by the MILC collaboration involving four lattice spacings ranging from 0.12 to 0.045 fm and up/down to strange quark mass ratios as low as 0.05. For the charm quark we use the Sheikholeslami-Wohlert action...

375. $B\to \pi$ semileptonic form factors from unquenched lattice QCD

Daping Du (Syracuse University)

27/06/2014, 16:30

Weak Decays and Matrix Elements

Talk

We update the lattice calculation of the $B\to \pi$ semileptonic form factors with a focus on the applications to the CKM matrix element $|V_{ub}|$. We use the MILC AsqTad 2+1-flavor lattice configurations at four lattice spacings and compute the matrix elements using the full-QCD valence quarks. We extrapolate the lattice data to continuum physics using the staggered chiral perturbation theory...

373. The B -> pi l nu and B_s -> K l nu form factors from 2+1 flavors of domain-wall fermions and relativistic b-quarks

Dr Taichi Kawanai (Brookhaven National Laboratory)

27/06/2014, 16:50

Weak Decays and Matrix Elements

Talk

We report results for the B→π and B_s→K semileptonic form factors using lattice QCD with domain-wall light quarks and relativistic b-quarks. We use the 2+1 flavor domain-wall Iwasaki gauge configurations generated by the RBC and UKQCD collaborations at two lattice spacings of a~0.08fm and a~0.11fm. Our lightest pion mass is about 290MeV. We perform the chiral and continuum extrapolations using...

318. Semileptonic form factors of pseudoscalar mesons from Nf=2+1+1 Twisted Mass lattice QCD

Mr Lorenzo Riggio (INFN)

27/06/2014, 17:10

Weak Decays and Matrix Elements

Talk

We present a lattice QCD determination of the vector and scalar form factors of the kaon semileptonic decay K->pi nu l , and of the D meson semileptonic decays D->(K/pi) nu l which are relevant for the extraction of the CKM matrix element |Vus|, |Vcd| and |Vcs| from experimental data. Our preliminary results are based on the gauge configurations produced by the European Twisted Mass...

184. Standrad Model contributions to B and Bs meson semileptonic decays

Heechang Na (University of Utah)

27/06/2014, 17:30

Weak Decays and Matrix Elements

Talk

We present our recent results on B to D, Bs to Ds, and Bs to K Standard Model tree level semileptonic decays. We have used MILC Nf=2+1 asqtad gauge configurations with two lattice spacings. For the valence quarks, we used NRQCD bottom quarks and HISQ light and charm quarks. The B to D and Bs to Ds semileptonic form factors can be used for better determination of the Bs to [mu^+ mu^-]...

283. Improved currents for B to D(*) ell nu form factors from Oktay-Kronfeld heavy quarks

Jon Bailey (Seoul National University)

27/06/2014, 17:50

Weak Decays and Matrix Elements

Talk

The CKM matrix element |V_{cb}| can be extracted by combining experimentally determined branching fractions for B to D(*) ell nu decays with form factors from the lattice. While successful, the precision of this approach has been limited by heavy-quark discretization effects. An improved version of the Fermilab action, the Oktay-Kronfeld action, can be used to reduce heavy-quark...

165. Non-perturbative study of the chromagnetic operator on the lattice

Vittorio Lubicz (Universita' Roma Tre)

27/06/2014, 18:10

Weak Decays and Matrix Elements

Talk

We describe our study of the chromomagnetic operator O_CM, which appears in the effective Hamiltonian describing DS=1 transitions in and beyond the Standard Model. Having dimension 5, the chromomagnetic operator is characterized by a rich pattern of mixing with other operators of equal and lower dimensionality. We have computed the coefficients of the mixing with the various dimension 5...