Engineering topics

Lin, C.-J. David

Publications and source records attributed to Lin, C.-J. David.

5 records

DOE OSTI2023

Lattice QCD Constraints on the Fourth Mellin Moment of the Pion Light Cone Distribution Amplitude using the HOPE method

The light-cone distribution amplitude (LCDA) of the pion contains information about the parton momentum carried by the quarks and is an important theoretical input for various predictions of exclusive processes at high energy, including the pion electromagnetic form factor. Progress towards constraining the fourth Mellin moment of the LCDA using the heavy-quark operator product expansion (HOPE) method is presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

The lattice extraction of the TMD soft function using the auxiliary field representation of the Wilson line

The transverse momentum dependent (TMD) soft function can be obtained by formulating the Wilson line in terms of auxiliary 1-dimensional fermion fields on the lattice. In this formulation, the directional vector of the auxiliary field in Euclidean space has the form ˜ 𝑛 = ¹𝑖𝑛0 ®0? 𝑛3º, where the time component is purely imaginary. The components of these complex directional vectors in the Euclidean space can be mapped directly to the rapidities of the Minkowski space soft function. We present the results of the one-loop calculation of the Euclidean space analog to the soft function using these complex directional vectors. As a result, we show that the calculation is valid only when the directional vectors obey the relation: j𝑟 j = j𝑛3𝑛0j ¡ 1, and that this result corresponds to a computation in Minkowski space with space-like directed Wilson lines. Finally, we show that a lattice calculable object can be constructed that has the desired properties of the soft function.

Francis, Anthony↗

DOE OSTI2022

Progress in calculation of the fourth Mellin moment of the pion light-cone distribution amplitude using the HOPE method

The pion light-cone distribution amplitude (LCDA) is a central non-perturbative object of interest for the calculation of high-energy exclusive processes in quantum chromodynamics. This article describes the progress in the lattice QCD calculation of the fourth Mellin moment of the pion LCDA using a heavy-quark operator product expansion (HOPE).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2013

Λ b →pl⁻ν¯ l form factors from lattice QCD with static b quarks

We present a lattice QCD calculation of form factors for the decay Λ b →pμ⁻ν¯ μ , which is a promising channel for determining the Cabibbo-Kobayashi-Maskawa matrix element |V ub | at the Large Hadron Collider. In this initial study we work in the limit of static b quarks, where the number of independent form factors reduces to two. We use dynamical domain-wall fermions for the light quarks, and perform the calculation at two different lattice spacings and at multiple values of the light-quark masses in a single large volume. Using our form factor results, we calculate the Λ b →pμ⁻ν¯ μ differential decay rate in the range 14 GeV²≤q²≤q² max , and obtain the integral ∫ q² max 14 GeV² [dΓ/dq²]dq²/|V ub |²=15.3±4.2 ps⁻¹. Combined with future experimental data, this will give a novel determination of |V ub | with about 15% theoretical uncertainty. The uncertainty is dominated by the use of the static approximation for the b quark, and can be reduced further by performing the lattice calculation with a more sophisticated heavy-quark action.

Detmold, William↗

DOE OSTI2012

Form factors for Lambda_b to Lambda transitions from lattice QCD

The rare baryonic decays Lb !Lm+m? and Lb !Lg can complement rare B meson decays in constraining models of new physics. In this work, we calculate the relevant Lb ! L transition form factors at leading order in heavy-quark effective theory using lattice QCD. Our analysis is based on RBC/UKQCD gauge field ensembles with 2+1 flavors of domain-wall fermions, and with lattice spacings of a?0:11 fm and a?0:08 fm. We compute appropriate ratios of three-point and two-point correlation functions for a wide range of source-sink separations, and extrapolate to infinite separation in order to eliminate excited-state contamination. We then extrapolate the form factors to the continuum limit and to the physical values of the light-quark masses.

Meinel, Stefan↗