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Xiangdong Ji12/08/2024, 08:30
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Yushan Su (University of Maryland)12/08/2024, 09:00
Parton distribution functions (PDFs) at large $x$ are difficult to be extracted from experimental data, but are extremely important in understanding hadron structures as well as searching for new physics beyond the Standard Model. We study the large $x$ PDFs under the framework of large momentum $P^z$ expansion of lattice quasi-PDFs. In the threshold limit, the matching kernel of quasi-PDF can...
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Rui Zhang12/08/2024, 09:25
We present a direct lattice QCD calculation of the $x$-dependence of the pion distribution amplitude (DA), which is performed using the quasi-DA in large momentum effective theory on a domain-wall fermion ensemble at physical quark masses and spacing $a\approx 0.084$ fm. The bare quais-DA matrix elements are renormalized in the hybrid scheme and matched to $\overline{\rm MS}$ with a...
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Fei Yao12/08/2024, 09:50
In this talk, I present the result of the next-to-next-to-leading order (NNLO) matching kernel for extracting light meson distribution amplitudes from lattice calculations of nonlocal Euclidean correlation functions. The renormalization is done in a state-of-the-art scheme. I also show some preliminary numerical test to demonstrate the impact of the NNLO matching.
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Ji-Hao Wang (Institute of Theoretical Physics, Chinese Academy of Sciences)12/08/2024, 10:45
We calculate the leading-twist light-cone distribution amplitude (LCDA) moments of mesons on MILC ensembles using the hyp-smeared clover action. For pseudoscalar mesons, we compute the first moments of the $K$ meson and the second moments of the $\pi$ and $K$ mesons. For vector mesons, we compute the first moments of the $K^{*}$ meson and the second moments of the $\rho$, $K^{*}$, and $\phi$ mesons.
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Anthony Grebe12/08/2024, 11:05
The pseudoscalar meson light-cone distribution amplitudes (LCDAs) are essential non-perturbative inputs for a range of high-energy exclusive processes in quantum chromodynamics. I will discuss progress towards determination of the low Mellin moments of pion and kaon LCDAs -- including the fourth moment of the pion LCDA -- by the HOPE Collaboration.
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Joseph Karpie12/08/2024, 11:35
Critical to the understanding of parton structure is the scale dependence of the distributions. By compared data at different scales one can test the validity of the factorization approximation. Typically the universal short distance scale dependence of the object is calculated in perturbation theory. We propose a method for calculating the scale dependence non-perturbatively from lattice QCD...
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Peter Petreczky12/08/2024, 13:15
We report the first lattice QCD computation of pion and kaon electromagnetic form factors, $F_M(Q^2)$,
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at large momentum transfer up to 10 and 28 GeV2, respectively. The calculations are performed using HISQ
action on fine lattices with physical quark massesi and Breit frame [1].
We test the QCD collinear factorization framework utilizing our high- $Q^2$ form factors at... -
Qi Shi12/08/2024, 13:45
We report a lattice calculation of $x$-dependent valence pion generalized parton distributions (GPDs) at zero skewness with multiple values of the momentum transfer $-t$. The calculations are based on an $N_f=2+1$ gauge ensemble of highly improved staggered quarks with Wilson-Clover valence fermion. The lattice spacing is 0.04 fm, and the pion valence mass is tuned to be 300 MeV. We determine...
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Herve Dutrieux (William and Mary)12/08/2024, 14:10
I will present the recent lattice calculation of the unpolarized generalized form factors by the Hadtruc collaboration. We use the pseudo-distribution formalism with an extended kinematic domain in $(\xi, t)$. I will discuss the limitations and improvement perspectives of this study.
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Joshua Miller12/08/2024, 14:35
The $x$-dependence of GPDs is still relatively unknown, but recent developments from lattice QCD with a new approach (PRD 106 (2022) 11, 114512) produce promising results from matrix elements calculated from any kinematic frame. Traditionally, GPDs are calculated in the symmetric frame, where the momentum transfer is evenly split between the initial and final states. In this talk, we present...
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Lisa Walter13/08/2024, 08:30
We focus on the Boer-Mulders function of the pion and use the CLS ensembles X650 (a = 0.098 fm), H102 (a = 0.085 fm) and N203 (a = 0.064 fm) to study this quantity and later allow for a controlled continuum extrapolation. The pion masses of these ensembles are approximately equal, as they range between 338 and 354 MeV. Here, preliminary results of the ongoing work are shown, including...
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Artur Avkhadiev13/08/2024, 08:55
This work presents a determination of the quark Collins-Soper kernel from quasi-TMD wavefunctions using lattice QCD and LaMET. This is the first such determination with systematic control of quark mass, operator mixing, and discretization artifacts. Furthermore, this work also achieves systematic control over the imaginary part of the LaMET matching coefficients at small transverse momentum...
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Yong Zhao13/08/2024, 09:20
The transverse-momentum-dependent distributions (TMDs), which are defined by gauge-invariant 3D parton correlators with staple-shaped lightlike Wilson lines, can be calculated from quark and gluon correlators fixed in the Coulomb gauge on a Euclidean lattice. These quantities can be expressed gauge-invariantly as the correlators of Coulomb-gauge-dressed fields, which reduce to the standard TMD...
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Xiang Gao (Argonne National Lab)13/08/2024, 09:50
We present the first lattice QCD calculation of the rapidity anomalous dimension of transverse-momentum-dependent distributions (TMDs), i.e. the Collins-Soper (CS) kernel, employing the recently proposed Coulomb-gauge-fixed quasi-TMD formalism as well as a chiral-symmetry-preserving lattice discretization. This unitary lattice calculation is conducted using the domain wall fermion...
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Qi-An Zhang13/08/2024, 10:45
We present a method to compute lightcone distribution amplitudes (LCDAs) of heavy meson within heavy quark effective theory (HQET). Our method utilizes quasi distribution amplitudes (quasi-DAs) with a large momentum component $P^z$. We point out that by sequentially integrating out $P^z$ and $m_H$, one can disentangle different dynamical scales. Integrating out $P^z$ allows to connect...
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Wayne Morris (National Yang Ming Chiao Tung University)13/08/2024, 11:15
The TMD soft function may be obtained by formulating the Wilson line in terms of auxiliary 1-dimensional fermion fields on the lattice. We take inspiration from heavy quark effective theory (HQET) in order to define the auxiliary field. Our computation takes place in the region of the lattice that corresponds to the “spacelike” region in Minkowski space in order to obtain the Collins soft...
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Yizhuang Liu (Jagiellonian University)13/08/2024, 11:40
In this talk I revisit the time-ordering issue of TMD soft factors based on coordinate-space analyticity properties of Wightman functions in Wightman-Osterwalder-Schrader QFTs.
In particular, I show that the TMD soft factor for the DY process in three rapidity regularization schemes can be smoothly connected to each other in a way that maintain certain crucial (S=S_t type) equalities...
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Michael Wagman13/08/2024, 13:15
I will present a new method for determining the energy spectrum of lattice QCD using the Lanczos algorithm. The method provides faster ground-state convergence than standard energy estimators and rigorous two-sided error bounds, while avoiding the exponential signal-to-noise degradation present using standard methods.
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Daniel Hackett13/08/2024, 13:45
We present a new method for extracting hadronic matrix elements from simultaneous analysis of two- and three-point correlation functions, based on the Lanczos algorithm. In applications to both synthetic and lattice data, we demonstrate its advantages in both signal-to-noise and treatment of excited states over previous analysis approaches. We discuss the potential improvements for quasi-PDF...
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Xiangpeng Wang (Technische Universität München)13/08/2024, 14:10
Off-lightcone Wilson-line operators are constructed using local operators connected by time-like or space-like Wilson lines, which ensure gauge invariance. Off-lightcone Wilson-line operators have broad applications in various contexts. For instance, space-like Wilson-line operators play a crucial role in determining quasi-distribution functions (quasi-PDFs), while time-like Wilson-line...
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Wei-yang Liu (Stony Brook University)13/08/2024, 14:40
We discuss a general framework for the evaluation of the parton distribution, distribution amplitudes as well as the form factors in light hadrons in the QCD vacuum. At medium resolution of the order of the inverse mean instanton size, the glue is mostly localized in single or pair of pseudoparticles, and globally constrained by the fluctuations of their topological charges. These...
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Prof. Yi-Bo Yang (ITP/CAS)14/08/2024, 08:30
We analyze the gauge fixing precision dependence of some non-local quark-blinear lattice operators interesting in computing parton physics for several measurements, using 5 lattice spacings ranging from 0.032 fm to 0.121 fm. Our results show that gauge dependent non-local measurements are significantly more sensitive to the precision of gauge fixing than anticipated. The impact of imprecise...
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Jinchen He (University of Maryland, College Park)14/08/2024, 09:00
Recently, it is proposed to compute Parton distribution in fixed Coulomb gauge without Wilson line, which could greatly improve the efficiency of lattice calculations. However, there are some concerns about the systematic uncertainties from Gribov copies, which correspond to the ambiguity in the nonperturbative gauge fixing, is not controlled. This work gives an assessment on the systematic...
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Dr Jun Zeng (Shanghai Jiao Tong University)14/08/2024, 09:20
Momentum distributions of quarks/gluons inside a light baryon in a hard exclusive process are encoded in the light-cone distribution amplitudes (LCDAs). In this work, we point out that the leading twist LCDAs of a light baryon can be obtained through a simulation of a quasi-distribution amplitude calculable on lattice QCD within the framework of the large-momentum effective theory. We...
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chao han14/08/2024, 09:40
We present a comprehensive investigation of leading-twist lightcone distribution amplitudes (LCDAs) and quasi distribution amplitudes (quasi-DAs) for light octet and decuplet baryons within large momentum effective theory. In LaMET, LCDAs can be factorized in terms of a hard kernel and quasi-DAs that are defined as spatial correlators and calculable on Lattice QCD.
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To renormalize... -
Jun Hua14/08/2024, 10:00
The baryon light-cone distribution amplitudes(LCDAs) are critical inputs for hard exclusive reactions involving large momentum transfer between the initial and final state hadron. We present a lattice calcuation for the entire x dependent baryon LCDA under large momentum effective theory. The numerically simulation is based on emsembles with 2+1 flavor stout smeared clover fermions and...
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Zhuoyi Pang (The Chinese University of Hong Kong, ShenZhen)14/08/2024, 11:00
In this talk, I'll report our earlier work on the factorization of quasi GPD based on collinear expansion. Using ward identity and BRST symmetry, we show how to get a gauge-invariant factorization form. We also discuss the inconsistency of the mixing channel results in literature: its origin and possible solutions.
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Jiunn-Wei Chen14/08/2024, 11:20
We compute the matching kernel of singlet quasi-parton distributions in the hybrid ratio scheme. Momentum conservation of the quasi-distributions is observed. However, the renormalization condition is complicated by the quark and gluon mixing.
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William Good (Michigan State University)14/08/2024, 11:50
We present the first attempt at using the hybrid-ratio renormalization scheme on gluon quasi-lightfront correlators from lattice quantum chromodynamics with $a \approx 0.12$ fm at pion masses $M_\pi \approx 310$ and $690$ MeV. We measured over 1.2 million two-point correlators and used momentum smearing and aggressive gauge link smearing for the gluon operator to obtain a reasonable level of...
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Mr Hao-Cheng Zhang14/08/2024, 12:15
We present some mathematical results for reconstructing the generalized parton distributions (GPDs) through the universal moment parameterization (GUMP) program. We elucidate several subtle issues observed in previous literature, particularly the relationship between formal summation and the Mellin-Barnes integral. Furthermore, we derive an asymptotic condition on the conformal moments of GPDs...
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