Calculation of B → D*lv form factor at zero recoil using the Oktay-Kronfeld action

Jon A Bailey,Yong-Chull Jang,Rajan Gupta,Tanmoy Bhattacharya,Sungwoo Park,Weonjong Lee,Jaehoon Leem,Boram Yoon

doi:10.1051/epjconf/201817513012

Jon A Bailey, Yong-Chull Jang + Show 6 more

Open Access

https://doi.org/10.1051/epjconf/201817513012

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Abstract

We present the first preliminary results for the semileptonic form factor hA1 (w = 1)/ρAj at zero recoil for the B → D*lv decay using lattice QCD with four flavors of sea quarks. We use the HISQ staggered action for the light valence and sea quarks (the MILC HISQ configurations), and the Oktay-Kronfeld (OK) action for the heavy valence quarks.

Highlights

The 4.1σ tension between recently updated values of the exclusive and inclusive |Vcb| [1, 2], and the 4.0σ tension between the standard model prediction of εK using the exclusive |Vcb| determined with lattice QCD inputs and the experimental value of εK [2] motivates highter precision lattice calculations of |Vcb|.At present, the largest error in exclusive |Vcb| comes from the about 1% heavy quark discretization error in the Fermilab action used in current calculations [3]
The largest error in exclusive |Vcb| comes from the about 1% heavy quark discretization error in the Fermilab action used in current calculations [3]
We present the first results on the semileptonic form factor hA1 (w = 1)/ρAj at zero recoil for the B → D∗ νdecay

Summary

Introduction

The 4.1σ tension between recently updated values of the exclusive and inclusive |Vcb| [1, 2], and the 4.0σ tension between the standard model prediction of εK using the exclusive |Vcb| determined with lattice QCD inputs and the experimental value of εK [2] motivates highter precision lattice calculations of |Vcb|. The largest error in exclusive |Vcb| comes from the about 1% heavy quark discretization error in the Fermilab action used in current calculations [3]. In case of the Fermilab action, the coefficients of the dimension 5 counter terms added for improvement are independent of m0. It is straight-forward to determine κcrit by fitting the pion spectra with respect to am0. 3. Determine the OK action coefficients using κcrit and measure 2-point pion correlators with point sources and sinks. X pseudoscalar vector spin-average κc (a fπ+ ) 0.048349(35)(9)(4) 0.048338(62)(11)(0) 0.048341(51)(10)(1)

Inconsistency

Analysis of R