Calculation of $ K→πlν$ form factor in $N_f = 2+1$ QCD at physical point on $(10 \text{fm})^3$

Abstract

We present our preliminary result of the form factor of K → πlν semileptonic decays on the large volume configuration, L ≈ 10 fm, with the physical m π and m K using the stout-smearing clover quark and Iwasaki gauge actions at a −1 = 2.333 GeV. From an interpolation using the data in small momentum transfers, we determine the semileptonic decay form factors at zero momentum transfer. The result is compared with the previous lattice calculations. We also estimate the value of |V us | by combining our result with the experimental value of the kaon semileptonic decay.

Kaon semileptonic form factors at the physical quark masses on large volumes in Nf = 2 + 1 lattice QCD

“…Our result of f + (0) is plotted in the left panel of Fig. 3 together with previous calculations [10,11,12,13,14,15,16,17,18,1,19]. Our result is roughly consistent with those results within 2 σ in the total error.…”

“…3. Some recent results determined using the K ℓ3 form factor [14,15,16,18,1,19] are also plotted together with the ones from the K ℓ2 decay process [4,7] and from |V ud | [2,3] through the unitarity of the CKM matrix. Our result agrees with the ones of the K ℓ2 determination.…”

“…For the BSM physics search, it is important to reduce our large systematic error. To do this, we plan to calculate the K ℓ3 form factor at a smaller [14,15,16,18,1,19] together with the ones determined from the K ℓ2 decay process [4,7]. The light blue and gray bands represent |V us | determined from the unitarity of the CKM matrix using |V ud | in Refs.…”

Kl3 form factors at the physical point on a (10.9 fm)Kakazu1, Ishikawa2, Ishizuka3 et al. 2020Phys. Rev. DSelf Cite206390View full textAdd to dashboardCite

“…In Eq. (14) it is assumed that t i ≤ t ≤ t f and two excited state contributions for the radial excited mesons and wrapping around effect, expressed by ΔA μ ð ⃗p; tÞ and ΔB μ ð ⃗p; tÞ, respectively, are leading contributions of excited states in the ratio. Other excited state contributions are denoted by the dots ðÁ Á ÁÞ term.…”

“…14, because in this case the effect has a desirable boundary condition dependence as in Eq. (14). A similar technique using combination of quark propagators with the periodic and antiperiodic boundary conditions in the temporal direction was employed in the B K calculation to effectively double the periodicity of the 3point function [21,22].…”