Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSemileptonic $B to D^{(ast)} ell u$ Decay Form Factors using the Oktay-Kronfeld Action
260
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report recent progress in calculating semileptonic form factors for the $bar{B} to D^ast ell bar{ u}$ and $bar{B} to D ell bar{ u}$ decays using the Oktay-Kronfeld (OK) action for bottom and charm quarks. We use the second order in heavy quark effective power counting $mathcal{O}(lambda^2)$ improved currents in this work. The HISQ action is used for the light spectator quarks. We analyzed four $2+1+1$-flavor MILC HISQ ensembles with $aapprox 0.09,mathrm{fm}$, $0.12,mathrm{fm}$ and $M_pi approx 220,mathrm{MeV}$, $310,mathrm{MeV}$: $a09m220$, $a09m310$, $a12m220$, $a12m310$. Preliminary results for $Bto D^astell u$ decays form factor $h_{A_1}(w)$ at zero recoil ($w=1$) are reported. Preliminary results for $B to D,ell u$ decays form factors $h_pm(w)$ over a kinematic range $1<w<1.3$ are reported as well.
rate research
Read More
We present an update on the calculation of $bar{B}to D^ast ell bar{ u}$ semileptonic form factor at zero recoil using the Oktay-Kronfeld bottom and charm quarks on $N_f=2+1+1$ flavor HISQ ensembles generated by the MILC collaboration. Preliminary results are given for two ensembles with $aapprox 0.12$ and $0.09$ fm and $M_piapprox 310$ MeV. Calculations have been done with a number of valence quark masses, and the dependence of the form factor on them is investigated on the $aapprox 0.12$ fm ensemble. The excited state is controlled by using multistate fits to the three-point correlators measured at 4--6 source-sink separations.
We report on our calculation of the B to D^(*) ell u form factors in 2+1 flavor lattice QCD. The Mobius domain-wall action is employed for light, strange, charm and bottom quarks. At lattice cutoffs 1/a sim 2.4, 3.6 and 4.5 GeV, we simulate bottom quark masses up to 0.7/a to control discretization errors. The pion mass is as low as 230 MeV. We extrapolate the form factors to the continuum limit and physical quark masses, and make a comparison with recent phenomenological analyses.
We update the lattice calculation of the $Btopi$ semileptonic form factors, which have important applications to the CKM matrix element $|V_{ub}|$ and the $Btopiell^+ell^-$ rare decay. We use MILC asqtad ensembles with $N_f=2+1$ sea quarks and over a range of lattice spacings $a approx 0.045$--$0.12$ fm. We perform a combined chiral and continuum extrapolation of our lattice data using SU(2) staggered chiral perturbation theory in the hard pion limit. To extend the results for the form factors to the full kinematic range, we take a functional approach to parameterize the form factors using the Bourrely-Caprini-Lellouch formalism in a model-independent way. Our analysis is still blinded with an unknown off-set factor which will be disclosed when we present the final results.
We report on our study of the B to D^(*) ell u semileptonic decays at zero and nonzero recoils in 2+1 flavor QCD. The Mobius domain-wall action is employed for light, charm and bottom quarks at lattice cutoffs 1/a = 2.5 and 3.6 GeV. We take bottom quark masses up to approx 2.4 times the physical charm mass to control discretization effects. The pion mass is as low as M_pi sim 310 MeV. We present our preliminary results for the relevant form factors and discuss the violation of heavy quark symmetry, which is a recent important isuue on the long-standing tension in the Cabibbo-Kobayashi-Maskawa matrix element |V_{cb}| between the exclusive and inclusive decays.
We discuss preliminary results for the vector form factors $f_+^{{pi,K}}$ at zero-momentum transfer for the decays $Dtopiell u$ and $Dto K ell u$ using MILCs $N_f = 2+1+1$ HISQ ensembles at four lattice spacings, $a approx 0.042, 0.06, 0.09$, and 0.12 fm, and various HISQ quark masses down to the (degenerate) physical light quark mass. We use the kinematic constraint $f_+(q^2)= f_0(q^2)$ at $q^2 = 0$ to determine the vector form factor from our study of the scalar current, which yields $f_0(0)$. Results are extrapolated to the continuum physical point in the framework of hard pion/kaon SU(3) heavy-meson-staggered $chi$PT and Symanzik effective theory. Our calculation improves upon the precision achieved in existing lattice-QCD calculations of the vector form factors at $q^2=0$. We show the values of the CKM matrix elements $|V_{cs}|$ and $|V_{cd}|$ that we would obtain using our preliminary results for the form factors together with recent experimental results, and discuss the implications of these values for the second row CKM unitarity.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
