Improved Semileptonic Form Factor Calculations in Lattice QCD

Abstract

We investigate the computational efficiency of two stochastic based alternatives to the Sequential Propagator Method used in Lattice QCD calculations of heavy-light semileptonic form factors. In the first method, we replace the sequential propagator, which couples the calculation of two of the three propagators required for the calculation, with a stochastic propagator so that the calculations of all three propagators are independent. This method is more flexible than the Sequential Propagator Method but introduces stochastic noise. We study the noise to determine when this method becomes competitive with the Sequential Propagator Method, and find that for any practical calculation it is competitive with or superior to the Sequential Propagator Method. We also examine a second stochastic method, the so-called ``one-end trick", concluding it is relatively inefficient in this context. The investigation is carried out on two gauge field ensembles, using the non-perturbatively improved Wilson-Sheikholeslami-Wohlert action with N_f=2 mass-degenerate sea quarks. The two ensembles have similar lattice spacings but different sea quark masses. We use the first stochastic method to extract $\mathcal{O}(a)$-improved, matched lattice results for the semileptonic form factors on the ensemble with lighter sea quarks, extracting f_+(0).

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Cited by in corpus (10)

• Nucleon isovector couplings from $N_f=2$ lattice QCD
• $D_s\to \eta ,{\eta }^{\prime }$ semileptonic decay form factors with disconnected quark loop contributions
• Stochastic method with low mode substitution for nucleon isovector matrix elements
• Octet baryon isovector charges from $N_f=2+1$ lattice QCD
• Calculation of fermion loops for ${\eta }^{\prime }$ and nucleon scalar and electromagnetic form factors
• A Stochastic Method for Computing Hadronic Matrix Elements
• Mellin moments of spin dependent and independent PDFs of the pion and rho meson
• Disconnected contributions to D-meson semi-leptonic decay form factors
• Hyperon couplings from $N_f=2+1$ lattice QCD
• Lattice calculations of Ds to eta and eta' decay form factors