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Mr Gregoris Spanoudes (University of Cyprus)24/07/2023, 13:30talk
We present one-loop perturbative results of the renormalization functions for a complete set of nonlocal quark bilinear operators containing an asymmetric staple-shaped Wilson line, using a family of improved lattice actions. This study is relevant for the nonperturbative investigations regarding the renormalization of the unpolarized, helicity and transversity transverse-momentum dependent...
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Ms Fei Yao (BNU)24/07/2023, 14:00talk
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...
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Asli Tandogan (University of Connecticut)24/07/2023, 14:30talk
The Covariant Parton Model is an appealing quark model framework that has been applied successfully to the description of structure functions, PDFs, and TMDs at the leading and subleading twist levels. In this contribution, the first application of the covariant parton model to quasi-PDFs is presented. Numerical results are presented and compared to lattice QCD results.
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Dr Rui Zhang (University of Maryland)24/07/2023, 15:00talk
In lattice-QCD calculations of parton distribution functions (PDFs) via large-momentum effective theory, the leading power (twist-three) correction appears as ${\cal O}(\Lambda_{\rm QCD}/P^z)$ due to the linear-divergent self-energy of Wilson line in quasi-PDF operators. For lattice data with hadron momentum $P^z$ of a few GeV, this correction is dominant in matching, as large as 30\% or more....
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Christian Zimmermann24/07/2023, 16:00talk
We use the operator product expansion (OPE) to relate hadronic Euclidean two current matrix elements to parton distribution functions (PDFs) resolving the dependence on the parton momentum fraction $x$. We are following the ansatz proposed by [arXiv:1709.03018]. In our calculation, we consider the valence quark PDFs for the proton. This requires the evaluation of a connected proton four-point...
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Yong Zhao24/07/2023, 16:30
In this talk, we will discuss a new method to calculate parton distribution functions (PDFs) from correlations of boosted quarks and gluons in the Coulomb gauge.
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Compared to the widely used quasi-PDFs defined from gauge-invariant Wilson-line operators, such correlations offer advantages including absence of linear power divergence, enhanced long-range precision, and accessibility to larger... -
Raza Sufian (Brookhaven National Lab)24/07/2023, 17:00talk
The excitation of nucleons to resonance structures via electromagnetic interactions is crucial for enhancing our comprehension of strong interactions within the realm of quark confinement. Moreover, accurate characterization of various resonance structures is also essential for maximizing the discovery potential of neutrino oscillation experiments. In this presentation, we present preliminary...
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Dr Robert Perry (Univerisity of Barcelona)24/07/2023, 17:30talk
The light-cone distribution amplitude (LCDA) of the pion carries information about the parton momentum distribution and is an important theoretical input into various predictions of exclusive measurements at high energy, including the pion electromagnetic form factor. We provide constraints on the fourth Mellin moment of the LCDA using the heavy quark operator product expansion (HOPE) method.
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Lisa Walter25/07/2023, 13:00talk
We focus on the Boer-Mulders function of the pion and for now use the CLS ensemble X650 (a = 0.098 fm, $m_{\pi}$ = 338 MeV) to study this quantity. Here, preliminary results of the ongoing work are shown, including extractions of the bare matrix elements and the rectangular Wilson loop. A main goal of the current work is to determine the largest momentum $P^z$ at which we still see a sufficient signal.
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Qi-An Zhang25/07/2023, 13:30talk
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) to compute the quark...
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Jun Hua (South China Normal University)25/07/2023, 14:00talk
We present a first lattice QCD calculation of the transverse-momentum-dependent wave functions (TMDWFs) of the pion using large-momentum effective theory. Numerical simulations are based on one ensemble with 2+1+1 flavors of highly improved staggered quarks action with lattice spacing $a=0.121$~fm from the MILC Collaboration, and one with 2 +1 flavor clover fermions and tree-level Symanzik...
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Aniket Sen25/07/2023, 14:30talk
Advancements in LaMET have made it possible to extract the transverse momentum dependent parton distribution functions (TMDPDFs) from first principles calculations. In this work, we calculate the two main ingredients necessary, the quasi-beam function and the soft function. We investigate the non-perturbative renormalization of these objects. Finally, we present results for the TMDPDF in...
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Artur Avkhadiev25/07/2023, 15:00talk
This work presents a determination of the quark Collins-Soper kernel from quasi-TMDs using lattice QCD and LaMET. The kernel is extracted in the range of transverse momentum scales $240\,\mathrm{MeV} <q_T< 1.6\,\mathrm{GeV}$ for hadron momenta $P < 2.2\,\mathrm{GeV}$, using quark masses corresponding to a close-to-physical value of the pion mass. An analysis of LaMET matching, including for...
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Óscar del Río García (Complutense University of Madrid)25/07/2023, 16:00talk
The determination of parton distributions with lattice simulations is a promising and rapidly growing direction in the physics of strong interactions. In particular, TMD factorization can be applied to a certain class of operators that can be computed within the lattice QCD approach. These are equal-time correlators usually called quasi-transverse-momentum dependent (qTMD) distributions. In...
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Andreas Schaefer25/07/2023, 16:30talk
The HL-LHC program will be sensitive to significantly smaller effects
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of BSM physics than probed so far. This implies that the quantitative understanding of non-perturbative Standard Model "backgrounds" has to be improved correspondingly. In this context Multiple Parton Interactions (MPIs) are a major concern. Theory efforts to improve their understanding focus on the simplest case, Double... -
Jianhui Zhang25/07/2023, 17:00talk
Multiparton distributions, among which the double parton distributions (DPDs) are the simplest and most important ones, play an important role in describing multiparton scattering processes in hadron collisions. In this talk, I'll discuss how they can be directly computed from correlations of equal-time nonlocal Euclidean operators on the lattice in the large hadron momentum limit.
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Yizhuang Liu (Jagiellonian University)25/07/2023, 17:30talk
In this talk we will provide a survey of three fundamental objects: quasi-TMDPDF, quasi-LFWF amplitudes and perturbative quark quasi-PDF that appears naturally in the application of LaMET to lattice calculation of various parton distribution functions. We demonstrate how factorization works for the three objects in the corresponding scaling limits, in a way that shares the common...
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Qi Shi26/07/2023, 13:00talk
We present a lattice QCD calculation of the transversity isovector- and isoscalar-quark parton distribution functions (PDFs) of the proton utilizing a perturbative matching at next-to-leading-order (NLO). Additionally, we determine the isovector and isoscalar tensor charge for the proton. The calculations are performed using a single ensemble of $N_f = 2 +1$ highly-improved staggered quarks...
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Peter Schweitzer26/07/2023, 13:30talk
The parton model is a well-known intuitive framework for first, exploratory studies of hadronic high energy reactions. The parton model can also be used to study nonperturbative properties of hadrons like structure functions and PDFs. The Wandzura-Wilczek relation is an example for that. The parton model approach has been (under the name "covariant parton model") extended to describe TMDs and...
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Jiunn-Wei Chen26/07/2023, 14:00talk
I will present the one-loop result of the matching kernels between the quasi-GPDs in hybrid renormalization and GPDs in the MS-bar scheme. We will also show the effect of the matching to modeled functions of GPDs.
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Xiangdong Ji26/07/2023, 14:30
I will discuss the relation between lattice computation of PDF moments from local and non-local operators. Consistency between the two approaches provide important constraints on LaMET calculations of partons on lattice.
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Xiang Gao (Argonne National Lab)26/07/2023, 15:00
We present a lattice QCD determination of Mellin moments of unpolarized generalized parton distributions (GPDs) of the proton from an analysis of the quasi-GPD matrix elements within the short-distance factorization framework. We perform our calculation on an $N_f$=2+1+1 twisted mass fermions ensemble with a clover improvement at lattice spacing $a=0.093$ fm and a pion mass of $m_\pi=260$ MeV....
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Jack Edward Holligan26/07/2023, 16:00talk
Generalized parton distribution functions (GPDs) describe the longitudinal momentum distribution within a hadron among its constituent partons as well as information about the momentum in the transverse direction. We calculate unpolarized and helicity GPDs using 2+1+1 flavors of highly improved staggered quarks in ensembles generated by the MILC collaboration at a=0.09 fm with a physical pion...
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Krzysztof Cichy26/07/2023, 16:30talk
We present the first lattice-QCD calculation of the proton's twist-3 axial quark GPDs using the LaMET approach. The lattice computation is performed using one ensemble of $N_f=2+1+1$ maximally twisted mass fermions with a clover term at a single lattice spacing of 0.093 fm and a pion mass of 260 MeV, employing three proton boosts up to 1.67 GeV. The light-cone GPDs are defined in the symmetric...
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Shohini Bhattacharya26/07/2023, 17:00talk
Recently, significant progress has been made in improving the efficiency and computational speed of lattice QCD calculations associated with Generalized Parton Distributions (GPDs). These advancements are a result of employing asymmetric frames, which differ from the commonly used symmetric frames, and introducing flexibility in the distribution of transferred momentum. A key element of our...
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Joshua Miller26/07/2023, 17:30talk
The few calculations of x-dependent GPDs performed in lattice QCD use the symmetric frame, where the momentum transfer is evenly divided between the momentum of the initial and final hadron states. To obtain the GPDs for several values of the momentum transfer in a computationally efficient method, we employ an asymmetric frame developed in PRD 106 (2022) 11, 114512. The kinematic setup we use...
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Fatma Pinar Aslantalk
Parton distribution functions (PDFs), $f(x)$, encode important nonperturbative information on the hadron structure as a function of light-cone momentum fraction $x$ which can be extracted from experimental measurements of cross sections. The quasi parton distribution functions (qPDFs) of hadron momentum $P_z$, $\tilde{f}(\tilde{x},P_z)$, introduced in the large-momentum effective field...
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