Many present lattice QCD approaches to calculate the parton distribution functions (PDFs) rely on a factorization formula or effective theory expansion of certain Euclidean matrix elements in boosted hadron states. In the quasi- and pseudo-PDF methods, the matching coefficient in the factorization or expansion formula includes large logarithms near the threshold, which arise from the subtle...
Nucleon transversity distribution is an essential quantity that reveals the nucleon's transverse spin structure. It also provides crucial inputs for understanding high-energy collision experiments involving transversely polarized nucleons. As a chiral-odd quantity, it's difficult to measure experimentally. Thus, ab initio lattice QCD calculations play an important complementary role. We report...
I describe the structure of the nucleon obtained within the pseudo-PDF framework. In particular I present recent calculations of the unpolarized, helicity and transversity distributions. We employ the distillation framework which allows a more complete sampling of the lattice and, together with momentum smearing, enables us to extend the range of Ioffe time accessible to our computation. ...
We present recent work on the calculation of the unpolarized isovector quark parton distribution function (PDF) of the nucleon at the physical point from lattice QCD utilizing a next-to-next-to-leading order (NNLO) matching. The main observables for these calculations are equal-time spatially-separated matrix elements of a boosted nucleon. There are two main strategies one can employ to obtain...
In this work, we present the first ab-initio numerical results of unpolarized proton's isovector transverse-momentum-dependent parton distribution functions (TMDPDFs), which are essential for exploring the inner pictures of nucleon, as well as for predicting the observables in multi-scale, non-inclusive high energy processes such as semi-inclusive deep-inelastic scattering and Drell-Yan...
We present a first calculation of the unpolarized proton's
isovector transverse-momentum-dependent parton distribution functions (TMDPDFs) from lattice QCD, which are essential to predict observables of multi-scale, semi-inclusive processes in the standard model. We use a $N_f=2+1+1$ MILC ensemble with valence clover fermions on a highly improved staggered quark sea (HISQ), and compute the...
According to large momentum effective theory (LaMET), the parton observables can be extracted from lattice calculations of quasi-observables through a perturbative matching relation. In this talk, I present a unified framework for the perturbative factorization connecting Euclidean correlations to light-cone correlations. We derive the flavor singlet and non-singlet matching kernel for the...
In large-momentum effective theory (LaMET), the transverse-momentum-dependent (TMD) light-front wave functions and soft functions can be extracted from the simulation of a four-quark form factor and equal-time correlation functions. In this work, using expansion by regions we provide a one-loop proof of TMD factorization of the form factor. For the one-loop validation, we also present a...
To calculate the transverse-momentum-dependent parton distribution functions (TMDPDFs) from lattice QCD, an important goal yet to be realized, it is crucial to establish a viable nonperturbative renormalization approach for linear divergences in the corresponding Euclidean quasi-TMDPDF correlators in large-momentum effective theory. We perform a first systematic study of the renormalization...
Soft function plays an important role in TMD factorization. We present a lattice QCD calculation for the rapidity-independent (or intrinsic) part of soft function at one-loop accuracy with a coherent normalization in large-momentum effective theory. The calculation is performed on CLS dynamic ensemble with a=0.098 fm and MILC ensemble with a=0.12 fm. Our results based on two ensembles are...
We present a state-of-the-art lattice QCD calculation of transverse momentum dependent wave function (TMDWF) of pion in large-momentum effective theory. The calculation is performed at clover fermion action ensembles with lattice spacing a=0.12fm generated by MILC Collaboration with and CLS ensembles with lattice spacing a=0.098fm. On each of the two ensembles we calculated three momentum up to...
