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BEGIN:VEVENT
SUMMARY:Extraction of PDF with the Hybrid Renormalization Scheme
DTSTART;VALUE=DATE-TIME:20200908T133000Z
DTEND;VALUE=DATE-TIME:20200908T140000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40926@indico.bnl.gov
DESCRIPTION:Speakers: Yong Zhao (Massachusetts Institute of Technology)\nR
ecently\, a hybrid scheme was proposed by the author and company to renorm
alize the quasi light-front correlations in the LaMET calculation of the P
DFs. The hybrid scheme reduces the systematic uncertainty in the renormali
zation at distances where the leading-twist expansion or perturbation theo
ry is expected to fail\, so that one can have a better-controlled Fourier
transform to the momentum space\, and reliably extract the PDF through a l
arge-momentum expansion in LaMET. In this talk\, I will show the results f
rom the analysis of existing lattice data with this hybrid scheme\, and co
mpare it to other schemes. We found that without making model assumptions
of the PDF\, the result is consistent with previous analyses in the modera
te-x region\, but have different qualitative behaviors in the small- and l
arge-x regions\, which is where the models are most sensitive to.\n\nhttps
://indico.bnl.gov/event/7252/contributions/40926/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40926/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pion and Kaon Distribution Amplitudes in Large-Momentum Effective
Theory
DTSTART;VALUE=DATE-TIME:20200908T154400Z
DTEND;VALUE=DATE-TIME:20200908T155600Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40934@indico.bnl.gov
DESCRIPTION:Speakers: Jun Hua (SJTU)\nWe present a lattice-QCD calculatio
n of $\\pi \, K$ distribution amplitudes using large-momentum effective th
eory (LaMET). Our results are calculted at 130-MeV pion mass with three di
fferent lattice spacing: 0.06\, 0.09 and 0.12 fm\, using 2+1+1 flavors of
highly improved staggered quarks (HISQ) ensembles generated by MILC collab
oration. We use the hybrid renormalization scheme for quasi light-front c
orrelations to properly renormalize both linear and logarithmic divergenc
es in correlation functions at lattice spacing a. The light-cone distribut
ion amplitude (LCDA) of $\\pi\, K$ are finally derived by inverse one-loop
mathching from quasi distribution amplitude .\n\nhttps://indico.bnl.gov/e
vent/7252/contributions/40934/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40934/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Proton GPDs from lattice QCD
DTSTART;VALUE=DATE-TIME:20200907T133000Z
DTEND;VALUE=DATE-TIME:20200907T140000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40927@indico.bnl.gov
DESCRIPTION:Speakers: Martha Constantinou (Temple University)\nWe will pre
sent new results of the proton unpolarized and helicity GPDs\, within latt
ice QCD. Their x-dependence is extracted using the quasi-distribution meth
od\, which requires matrix elements of moving hadrons coupled with non-loc
al operators. We use momentum boost up to 1.67 GeV\, and momentum transfer
squared up to 1 GeV^2. The calculation is performed on an Nf=2+1+1 ensemb
le of twisted mass fermions with a clover improvement\, reproducing a pion
mass of 260 MeV. The quasi-GPDs are matched to their light-cone counterpa
rts using one-loop perturbation theory within Large Momentum Effective The
ory (LaMET).\n\nhttps://indico.bnl.gov/event/7252/contributions/40927/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40927/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Valance parton distribution of pion from fine lattices
DTSTART;VALUE=DATE-TIME:20200907T152000Z
DTEND;VALUE=DATE-TIME:20200907T155000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40933@indico.bnl.gov
DESCRIPTION:Speakers: Xiang Gao (BNL&THU)\nWe present a high-statistics la
ttice QCD determination of the valence parton distribution function (PDF)
of pion\, with a mass of 300 MeV\, using HISQ gauge ensambles with two ver
y fine lattice spacings of a = 0.06 fm and 0.04 fm. Our analysis use both
RI-MOM and ratio-based schemes to renormalize the equal-time bi-local quar
k-bilinear matrix elements of pions boosted up to 2.4 GeV momenta. We reco
nstruct the x-dependent PDF\, as well as infer the first few even moments
of the PDF using the 1-loop perturbative LaMET framework. We also present
preliminary results for pion PDF with physical mass from DWF calculations.
This talk is based on arXiv: 2007.06590.\n\nhttps://indico.bnl.gov/event/
7252/contributions/40933/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40933/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Collins-Soper Kernel for TMD Evolution from Lattice QCD
DTSTART;VALUE=DATE-TIME:20200911T133000Z
DTEND;VALUE=DATE-TIME:20200911T140000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40935@indico.bnl.gov
DESCRIPTION:Speakers: Phiala Shanahan (MIT)\nThe Collins-Soper kernel rela
tes transverse momentum-dependent parton distribution functions at differe
nt energy scales. For small parton transverse momentum qT ∼ ΛQCD\, this
kernel is non-perturbative and can only be determined with controlled unc
ertainties through experiment or first-principles calculations. I will des
cribe an exploratory study using quenched lattice QCD to determine the Nf
= 0 Collins-Soper kernel at scales in the range 250 MeV \n\nhttps://indico
.bnl.gov/event/7252/contributions/40935/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40935/
END:VEVENT
BEGIN:VEVENT
SUMMARY:NNLO Correction to Quark Quasi Distribution Functions
DTSTART;VALUE=DATE-TIME:20200908T140000Z
DTEND;VALUE=DATE-TIME:20200908T143000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40931@indico.bnl.gov
DESCRIPTION:Speakers: Ruilin Zhu (Nanjing Normal University)\nWe present t
he first next-to-next-to-leading order (NNLO) calculation of quark quasi
parton distribution functions (PDFs) in the large momentum effective the
ory. The nontrivial factorization at this order is established explicitly
and the full analytic matching coefficients between the quasi distribut
ion and the lightcone distribution are derived for the first time. We
demonstrate that the NNLO numerical contributions can improve the behav
ior of the extracted PDFs sizably.\nWith the unprecedented precision stud
y of nucleon tomography at the planned electron-ion collider\, high precis
ion Lattice QCD simulations with our NNLO results implemented will enable
to test the QCD theory and revolutionize our understanding of the funda
mental structure of nucleon/nucleus.\n\nhttps://indico.bnl.gov/event/7252/
contributions/40931/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40931/
END:VEVENT
BEGIN:VEVENT
SUMMARY:One-Loop Matching for Spin-Dependent Quasi-TMDs
DTSTART;VALUE=DATE-TIME:20200907T155000Z
DTEND;VALUE=DATE-TIME:20200907T160200Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40930@indico.bnl.gov
DESCRIPTION:Speakers: Stella Schindler (MIT)\nTransverse-momentum-dependen
t parton distribution functions (TMDPDFs) provide a unique probe of the th
ree-dimensional spin structure of hadrons. We construct spin-dependent qua
si-TMDPDFs that are amenable to lattice QCD calculations and that can be u
sed to determine spin-dependent TMDPDFs. We calculate the short-distance c
oefficients connecting spin-dependent TMDPDFs and quasi-TMDPDFs at one-loo
p order. We find that the helicity and transversity distributions have the
same coefficient as the unpolarized TMDPDF. We also argue that the same i
s true for pretzelosity and that this spin universality of the matching wi
ll hold to all orders in $\\alpha_s$. Thus\, it is possible to calculate r
atios of these distributions as a function of longitudinal momentum and tr
ansverse position utilizing simpler Wilson line paths than have previously
been considered.\n\nhttps://indico.bnl.gov/event/7252/contributions/40930
/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40930/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ioffe time pseudo-distributions from Lattice QCD
DTSTART;VALUE=DATE-TIME:20200910T140000Z
DTEND;VALUE=DATE-TIME:20200910T143000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40932@indico.bnl.gov
DESCRIPTION:Speakers: Joe Karpie (Columbia U)\nIn this presentation\, we f
ocus on the pseudo-PDF method of calculating parton distributions. We use
a Euclidean space matrix element\, called the Ioffe-time pseudo distributi
on\, and Short Distance Factorization\, which allows data from all momenta
to contribute in the analysis\, to obtain parton distributions. We presen
t the latest lattice results from the HadStruc collaboration\, discuss sev
eral lattice systematics\, discuss the inverse problem universal to PDF de
terminations\, and perform a comparison with the pertinent phenomenologica
l determinations.\n\nhttps://indico.bnl.gov/event/7252/contributions/40932
/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40932/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Direct computation of light quarks and strange helicity PDFs with
lattice QCD
DTSTART;VALUE=DATE-TIME:20200910T143000Z
DTEND;VALUE=DATE-TIME:20200910T150000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40929@indico.bnl.gov
DESCRIPTION:Speakers: Floriano Manigrasso (University of Cyprus)\nWe prese
nt the first lattice QCD computation of the light quarks and strange helic
ity PDFs. We used a $N_f=2+1+1$ lattice ensemble generated by the Exten
ded Twisted Mass collaboration (ETMC)\, with pion mass $M_\\pi\\approx 25
0\\\;{\\rm GeV}$\, $M_\\pi L \\approx 3.8$ and lattice spacing $a= 0.0938(
2)(3)\\\;\\\;{\\rm fm}$. Momentum smearing is employed in order to improve
the signal-to-noise ratio\, allowing for the computation of the matrix el
ements up to nucleon boost momentum $P_3=1.24\\\,{\\rm GeV}$.\n\nhttps://i
ndico.bnl.gov/event/7252/contributions/40929/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40929/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hybrid Renormalization for Quasi Light-Front Correlations in Large
-Momentum Effective Theory
DTSTART;VALUE=DATE-TIME:20200908T152000Z
DTEND;VALUE=DATE-TIME:20200908T153200Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40936@indico.bnl.gov
DESCRIPTION:Speakers: Jianhui Zhang (Beijing Normal University)\nIn large-
momentum effective theory (LaMET)\, the quasi light-front correlations cal
culated on lattice contain both linear and logarithmic divergences in the
lattice spacing\, and thus need to be properly renormalized. The commonly
used renormalization strategy in the literature has the problem of introdu
cing extra non-perturbative effects at large distance. In this talk\, I pr
esent a hybrid renormalization procedure that avoids this problem and is w
ell-suited for matching the lattice correlations to those in the continuum
MSbar scheme. Also addressed are several other issues that are important
in extracting parton physics using LaMET.\n\nhttps://indico.bnl.gov/event/
7252/contributions/40936/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40936/
END:VEVENT
BEGIN:VEVENT
SUMMARY:UV divergence of the quasi-PDF operator under the lattice regulari
zation
DTSTART;VALUE=DATE-TIME:20200908T155600Z
DTEND;VALUE=DATE-TIME:20200908T160800Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40937@indico.bnl.gov
DESCRIPTION:Speakers: Yikai Huo (Columbia University)\nEven since the quas
i parton distribution function (PDF) was proposed within the large-momentu
m effective theory (LaMET) framework\, its renormalization under lattice r
egularization has been a central challenge due to the existence of linear
divergences. Previous theoretical studies have shown that the quasi-PDF op
erator is multiplicatively renormalizable and the linear divergence comes
from the gauge link in the Wilson line only. Thus\, we can extract the lin
ear divergence from various quantities\, e.g.\, the Wilson loop or the off
-shell quark matrix element using the regularization independent momentum
subtracted (RI/MOM) schemes. In this talk\, we discuss and compare the lin
ear divergence extracted from different methods\, with the calculation bei
ng carried out using the MILC configurations with the lattice spacing from
$0.03$ fm to $0.12$ fm.\n\nhttps://indico.bnl.gov/event/7252/contribution
s/40937/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40937/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matching for the twist-3 PDFs $g_T(x)$\, $e(x)$ and $h_L(x)$: succ
ess or failure?
DTSTART;VALUE=DATE-TIME:20200911T143000Z
DTEND;VALUE=DATE-TIME:20200911T150000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40939@indico.bnl.gov
DESCRIPTION:Speakers: Shohini Bhattacharya (Graduate Student)\nThe perturb
ative procedure of matching within Large Momentum Effective Theory connect
s the quasi-parton distributions to the light-cone distributions that ente
r physical processes. This procedure has demonstrated success in the extr
action of the twist-2 PDFs from lattice QCD. We explore the formalism of m
atching\, for the first time\, for the twist-3 PDFs $g_T(x)$\, $e(x)$ and
$h_L(x)$. We make several non-trivial observations\, all of which arise fr
om the presence of singular zero-mode contributions in the perturbative r
esults of the light-cone and quasi-PDFs. While matching seems possible for
$g_T(x)$\, zero-mode contributions could pose a challenge for the matchin
g in the case of $e(x)$ and $h_L(x)$.\n\nhttps://indico.bnl.gov/event/7252
/contributions/40939/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40939/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hadron structure from current-current correlation functions in lat
tice QCD
DTSTART;VALUE=DATE-TIME:20200910T133000Z
DTEND;VALUE=DATE-TIME:20200910T140000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40938@indico.bnl.gov
DESCRIPTION:Speakers: Raza Sufian (Jefferson Lab)\nWe present how partonic
structure of hadrons can be extracted from matrix elements of two spatial
ly-separated currents\, which are computable directly in lattice QCD and c
an be factorized into parton distribution functions with calculable hard c
oefficients. We demonstrate the recently derived one-loop matching coeffic
ient has a well-controlled behavior in Ioffe-time\, for example\, in a spe
cific calculation of pion valence quark distribution. We discuss issues in
obtaining PDFs from the factorized matrix elements which involve an inver
se problem - common to the extraction of PDFs from lattice QCD calculation
s or experimental data and what would require in a lattice calculation to
discriminate between different large $x$ behaviors of pion valence PDF.\n\
nhttps://indico.bnl.gov/event/7252/contributions/40938/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40938/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Extraction of Next-to-Next-to-Leading-Order PDFs from Lattice QCD
Calculations
DTSTART;VALUE=DATE-TIME:20200908T153200Z
DTEND;VALUE=DATE-TIME:20200908T154400Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40943@indico.bnl.gov
DESCRIPTION:Speakers: Zheng-Yang Li (Peking University)\nQuark correlation
functions in position space are calculable in lattice QCD and factorizabl
e into parton distribution functions with matching coefficients perturbati
vely calculable to all orders in QCD\, which provides a way to extract PDF
s from lattice QCD calculation. We present for the first time complete nex
t-to-next-to-leading-order calculation of valence-quark matching coefficie
nts. We find that theoretical uncertainties are improving with higher orde
r contributions. Our method of calculations can be readily generalized to
evaluate sea-quark matching coefficients and gluon correlation functions\,
putting the program to extract partonic structure of hadrons from lattice
QCD calculations to be comparable with that from experimental measurement
s.\n\nhttps://indico.bnl.gov/event/7252/contributions/40943/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40943/
END:VEVENT
BEGIN:VEVENT
SUMMARY:B-meson distribution amplitude
DTSTART;VALUE=DATE-TIME:20200910T154400Z
DTEND;VALUE=DATE-TIME:20200910T155600Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40941@indico.bnl.gov
DESCRIPTION:Speakers: Shuai Zhao (ODU/JLab)\nWe propose the approach for l
attice investigation of light-cone distribution amplitudes of heavy-light
mesons\, such as B-meson\, using both the formalism of quasi- and pseudo-d
istributions. We discuss the multiplicative renormalizability of the off-l
ight-cone HQET operator with the aid of auxiliary field approach\, and det
ermine the perturbative matching coefficient entering the hard-collinear f
actorization formula at the one-loop accuracy within the large momentum ef
fective theory. We further explore the short distance behavior of B-meson
Ioffe-time distribution amplitude (ITDA) and construct an ultraviolet fini
te reduced ITDA of B-meson\, which guarantees that the continuum limit exi
sts on the lattice.\n\nhttps://indico.bnl.gov/event/7252/contributions/409
41/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40941/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Transverse momentum dependent factorization for lattice observable
s
DTSTART;VALUE=DATE-TIME:20200907T143000Z
DTEND;VALUE=DATE-TIME:20200907T150000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40946@indico.bnl.gov
DESCRIPTION:Speakers: Vladimirov Alexey (Regensburg University)\nI present
the derivation of the factorization theorem for the quasi-transverse-mome
ntum-dependent (quasi-TMD) operator\, within the soft collinear effective
field theory framework. The factorized expression is built from the physic
al TMD distribution\, and a nonperturbative lattice related factor. The la
ttice related functions cancel in appropriately constructed ratios. These
ratios could be used to explore various properties of TMD distributions\,
for instance\, the nonperturbative evolution kernel (Collins-Soper kernel)
. A discussion of such ratios and the related continuum properties of TMDs
is presented.\n\nhttps://indico.bnl.gov/event/7252/contributions/40946/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40946/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Connecting quasi and pseudo distributions in nongauge theories
DTSTART;VALUE=DATE-TIME:20200908T143000Z
DTEND;VALUE=DATE-TIME:20200908T150000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40947@indico.bnl.gov
DESCRIPTION:Speakers: Christopher Monahan (College of William and Mary)\nI
explore the explicit relationship between the LaMET and pseudo-PDF approa
ches to collinear hadron structure in the context of a scalar theory\, and
demonstrate explicitly their equivalence at one loop in perturbation theo
ry. Scalar field theory removes complications associated with gauge theori
es that enable complete calculations of all quantities\, such as the Ioffe
-time distribution at arbitrary field separation\, and demonstrate explici
tly their interrelationships. This provides the ideal playground for analy
sing and clarifying the main features of both quasi- and pseudo-PDFs.\n\nh
ttps://indico.bnl.gov/event/7252/contributions/40947/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40947/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lattice QCD calculations of TMD soft function through large-moment
um effective theory
DTSTART;VALUE=DATE-TIME:20200911T140000Z
DTEND;VALUE=DATE-TIME:20200911T143000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40944@indico.bnl.gov
DESCRIPTION:Speakers: Qi-An Zhang (T.D. Lee Institute)\nThe transverse-mom
entum-dependent (TMD) soft function is a key ingredient in QCD factorizati
on of Drell-Yan and other processes with relatively small transverse momen
tum. We present a lattice QCD study of this function at moderately large r
apidity on a 2+1 flavor CLS dynamic ensemble with $a=0.098$ fm. We extract
the rapidity-independent (or intrinsic) part of the soft function through
a large-momentum-transfer pseudo-scalar meson form factor and its quasi-T
MD wave function using leading-order factorization in large-momentum effe
ctive theory. We also investigate the rapidity-dependent part of the soft
function---the Collins-Soper evolution kernel---based on the large-momentu
m evolution of the quasi-TMD wave function.\n\nhttps://indico.bnl.gov/even
t/7252/contributions/40944/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40944/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nucleon Gluon Distribution Function from 2+1+1-Flavor Lattice QCD
DTSTART;VALUE=DATE-TIME:20200911T155600Z
DTEND;VALUE=DATE-TIME:20200911T160800Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40928@indico.bnl.gov
DESCRIPTION:Speakers: Zhouyou Fan (Michigan State University)\nThe parton
distribution functions (PDFs) provide process-independent information abou
t the quarks and gluons inside hadrons. Although the gluon PDF can be obta
ined from a global fit to experimental data\, it is not constrained well i
n the large-$x$ region. Theoretical gluon-PDF studies are much fewer than
those of the quark PDFs. In this work\, we present the first lattice-QCD r
esults that access the $x$-dependence of the gluon unpolarized PDF of the
nucleon. The lattice calculation is carried out with nucleon momenta up to
2.16~GeV\, lattice spacing $a\\approx0.12$~fm\, with valence pion masses
of 310 and 690~MeV. \nWe use reduced Ioffe-time distributions to cancel th
e renormalization and implement a one-loop perturbative pseudo-PDF matchin
g to the lightcone distribution. Our matrix element results in coordinate
space are consistent with those obtained from the global PDF fits of CT18
NNLO and NNPDF3.1 NNLO. Our fitted gluon PDF extrapolated to the physical
pion mass gives consistent results in the $x > 0.3$ region.\n\nhttps://ind
ico.bnl.gov/event/7252/contributions/40928/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40928/
END:VEVENT
BEGIN:VEVENT
SUMMARY:TMD parton densities from LaMET
DTSTART;VALUE=DATE-TIME:20200907T140000Z
DTEND;VALUE=DATE-TIME:20200907T143000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40948@indico.bnl.gov
DESCRIPTION:Speakers: Yizhuang Liu (TDLI)\nTMD parton densities are import
ant for its theoretical value and for better understanding of Hadron struc
ture. The first principle calculation of them from LaMET framework turns o
ut to be non-trivial due to problems caused by soft function subtraction.
In this talk I will talk about recent progress on lattice calculation of T
MD soft functions and parton densities from the LaMET framework. I will sh
ow that the TMD soft function in off-light-cone regularization scheme can
be extracted from heavy or light meson form factors\, and with the help of
the soft function\, the universal scheme independent TMD-PDFs cane be obt
ained once combining them with lattice calculable quasi-TMD PDFs.\n\nhttps
://indico.bnl.gov/event/7252/contributions/40948/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40948/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Decomposing the proton spin to quark and gluon contributions
DTSTART;VALUE=DATE-TIME:20200910T155600Z
DTEND;VALUE=DATE-TIME:20200910T160800Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40949@indico.bnl.gov
DESCRIPTION:Speakers: Kyriakos Hadjiyiannakou (University of Cyprus)\nWe w
ill present results on the spin decomposition and the momentum distributio
n among quarks and gluons in the proton. Techniques for lattice QCD simula
tions at the physical pion mass applied for the computation of sea-quark a
nd gluon contributions will be presented. We will discuss several challeng
es and perspectives for future developments.\n\nhttps://indico.bnl.gov/eve
nt/7252/contributions/40949/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40949/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hadronic tensor with lattice QCD and elastic form factors
DTSTART;VALUE=DATE-TIME:20200910T152000Z
DTEND;VALUE=DATE-TIME:20200910T153200Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40945@indico.bnl.gov
DESCRIPTION:Speakers: Jian Liang (University of Kentucky)\nWe propose to s
tudy the hadronic tensor with lattice QCD\, which works in all the energy
ranges (from elastic scattering to inelastic scattering and on to deep ine
lastic scattering) and is related to many important physical problems. A c
hallenge of this approach in the study of PDFs is to access high momentum
and energy transfers\, and numerical tests show that small lattice spacing
s are essential for this purpose. The need of fine lattices appear to be a
common problem faced by the lattice PDF community. On the other hand\, be
fore lattices with very fine spacing are available\, the hadronic tensor c
an be used to study the nucleon elastic form factors and low-energy scatte
rings such as the neutrino-nucleon scattering which is of significant phys
ical importance. Numerically\, the nucleon electric form factors (connecte
d insertions only) calculated by means of 3-point functions for both $u$ a
nd $d$ quarks are found to be consistent within errors with those deduced
from the hadronic tensor.\n\nhttps://indico.bnl.gov/event/7252/contributio
ns/40945/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40945/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nucleon Ioffe-time Pseudo-distributions from Distillation
DTSTART;VALUE=DATE-TIME:20200910T153200Z
DTEND;VALUE=DATE-TIME:20200910T154400Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40951@indico.bnl.gov
DESCRIPTION:Speakers: Colin Egerer ()\nThe pseudo-distribution formalism i
s one such lattice methodology capable of extracting light-cone distributi
ons from matrix elements of suitably constructed Euclidean non-local opera
tors of a spacelike extent. Leveraging the distillation spatial smearing p
rogram\, we extract the unpolarized isovector quark distribution of the nu
cleon via a direct 1-loop matching of the Ioffe-time pseudo-distribution a
nd model PDFs. We benchmark the efficacy and systematics inherent to this
choice by also extracting the PDF from the matched light-cone Ioffe-time d
istribution. The tempering of excited-states and improved spatial sampling
afforded by distillation is likewise seen to allow for a meaningful simul
taneous determination of the isovector quark and sea-quark distributions.
Comparisons with phenomenological determinations are made.\n\nhttps://indi
co.bnl.gov/event/7252/contributions/40951/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40951/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Twist-3 PDFs from lattice QCD: g_T(x)
DTSTART;VALUE=DATE-TIME:20200911T152000Z
DTEND;VALUE=DATE-TIME:20200911T153200Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40950@indico.bnl.gov
DESCRIPTION:Speakers: Krzysztof Cichy (Adam Mickiewicz University)\nWe pre
sent a lattice exploration of the isovector flavor combination of the nucl
eon's twist-3 helicity PDF g_T(x)\, using twisted mass clover fermions. We
employ the quasi-distribution approach at three values of the nucleon boo
st up to 1.7 GeV to connect the lattice-extracted matrix elements\, renorm
alized in the RI/MOM scheme\, to light-cone distributions\, applying the m
atching procedure that we developed in parallel. We also calculate the twi
st-2 helicity distribution g_1(x) to test the Wandzura-Wilczek approximati
on for g_T(x) and find that it works well for a broad range of Bjorken-x.\
n\nhttps://indico.bnl.gov/event/7252/contributions/40950/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40950/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gluon pseudo-distributions at short distances: Forward case
DTSTART;VALUE=DATE-TIME:20200911T154400Z
DTEND;VALUE=DATE-TIME:20200911T155600Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40952@indico.bnl.gov
DESCRIPTION:Speakers: Wayne Morris (Old Dominion University)\nWe present t
he results that are necessary in the ongoing lattice calculations of the g
luon parton distribution functions (PDFs) within the pseudo-PDF approach.
We give a classification of possible two-gluon correlator functions and id
entify those that contain the invariant amplitude determining the gluon PD
F in the light-cone $z^2 \\to 0$ limit. One-loop calculations have been pe
rformed in the coordinate representation and in an explicitly gauge-invari
ant form. We made an effort to separate ultraviolet (UV) and infrared (IR)
sources of the $\\ln (−z^2)$-dependence at short distances $z^2$. The U
V terms cancel in the reduced Ioffe-time distribution (ITD)\, and we obtai
n the matching relation between the reduced ITD and the light-cone ITD. Us
ing a kernel form\, we get a direct connection between lattice data for th
e reduced ITD and the normalized gluon PDF. We also show that our results
may be used for a rather straightforward calculation of the one-loop match
ing relations for quasi-PDFs.\n\nhttps://indico.bnl.gov/event/7252/contrib
utions/40952/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40952/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Welcome
DTSTART;VALUE=DATE-TIME:20200907T131500Z
DTEND;VALUE=DATE-TIME:20200907T133000Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40953@indico.bnl.gov
DESCRIPTION:Speakers: Ji Xiangdong ()\nhttps://indico.bnl.gov/event/7252/c
ontributions/40953/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40953/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Determining the Nonperturbative Collins-Soper Kernel From TMD Obse
rvables Using Lattice QCD
DTSTART;VALUE=DATE-TIME:20200911T153200Z
DTEND;VALUE=DATE-TIME:20200911T154400Z
DTSTAMP;VALUE=DATE-TIME:20211204T125706Z
UID:indico-contribution-7252-40942@indico.bnl.gov
DESCRIPTION:Speakers: Maximilian Schlemmer (University of Regensburg)\nI p
resent the lattice calculation and results for the nonpertrubative Collins
-Soper (CS) kernel\, which describes the energy-dependence of the transver
se momentum-dependent parton distribution functions (TMDPDFs). The CS kern
el is extracted from the ratios of the quasi-TMD taken at different moment
a. \nThe analysis is done with dynamical fermions for different polarizati
on cases of quasi-TMD observables with staple shaped Wilson lines\, for th
ree different CLS ensembles at different lattice spacing and fixed pion ma
ss. \nThe non-perturbative lattice CS kernel shows good agreement with an
experimental extraction of the CS kernel. Furthermore a comparison with tw
o previous explorative lattice studies is presented.\n\nhttps://indico.bnl
.gov/event/7252/contributions/40942/
LOCATION:Zoom
URL:https://indico.bnl.gov/event/7252/contributions/40942/
END:VEVENT
END:VCALENDAR