scholarly journals The ρ-meson light-cone distribution amplitudes from lattice QCD

2017 ◽  
Vol 2017 (4) ◽  
Author(s):  
Vladimir M. Braun ◽  
Peter C. Bruns ◽  
Sara Collins ◽  
John A. Gracey ◽  
Michael Gruber ◽  
...  
Keyword(s):  
Lattice Qcd ◽  
Light Cone

scholarly journals Light-cone sum rules for proton decay

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Ulrich Haisch ◽  
Amando Hala
Keyword(s):  
Lattice Qcd ◽  
Light Cone ◽  
Sum Rules ◽  
State Of The Art ◽  
Form Factors ◽  
Baryon Number ◽  
Proton Decay ◽  
Matrix Elements ◽  
Decay Channels ◽  
Systematic Uncertainties

Abstract We estimate the form factors that parametrise the hadronic matrix elements of proton-to-pion transitions with the help of light-cone sum rules. These form factors are relevant for semi-leptonic proton decay channels induced by baryon-number violating dimension-six operators, as typically studied in the context of grand unified theories. We calculate the form factors in a kinematical regime where the momentum transfer from the proton to the pion is space-like and extrapolate our final results to the regime that is relevant for proton decay. In this way, we obtain estimates for the form factors that show agreement with the state-of-the-art calculations in lattice QCD, if systematic uncertainties are taken into account. Our work is a first step towards calculating more involved proton decay channels where lattice QCD results are not available at present.

scholarly journals Light-Cone Parton Distribution Functions from Lattice QCD

2018 ◽  
Vol 121 (11) ◽  
Author(s):  
Constantia Alexandrou ◽  
Krzysztof Cichy ◽  
Martha Constantinou ◽  
Karl Jansen ◽  
Aurora Scapellato ◽  
...  
Keyword(s):  
Lattice Qcd ◽  
Parton Distribution ◽  
Light Cone ◽  
Distribution Functions ◽  
Parton Distribution Functions

scholarly journals Nucleon’s energy–momentum tensor form factors in light-cone QCD

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
K. Azizi ◽  
U. Özdem
Keyword(s):  
Perturbation Theory ◽  
Lattice Qcd ◽  
Chiral Perturbation Theory ◽  
Light Cone ◽  
Energy Momentum Tensor ◽  
Form Factors ◽  
Momentum Tensor ◽  
Tensor Form ◽  
Chiral Perturbation ◽  
Theoretical Predictions

Abstract We use the energy–momentum tensor (EMT) current to compute the EMT form factors of the nucleon in the framework of the light cone QCD sum rule formalism. In the calculations, we employ the most general form of the nucleon’s interpolating field and use the distribution amplitudes (DAs) of the nucleon with two sets of the numerical values of the main input parameters entering the expressions of the DAs. The directly obtained results from the sum rules for the form factors are reliable at $$ Q^2\ge 1$$Q2≥1 GeV$$^2 $$2: to extrapolate the results to include the zero momentum transfer squared with the aim of estimation of the related static physical quantities, we use some fit functions for the form factors. The numerical computations show that the energy–momentum tensor form factors of the nucleon can be well fitted to the multipole fit form. We compare the results obtained for the form factors at $$ Q^2=0 $$Q2=0 with the existing theoretical predictions as well as experimental data on the gravitational form factor d$$_1^q(0)$$1q(0). For the form factors M$$_2^q (0)$$2q(0) and J$$^q(0)$$q(0) a consistency among the theoretical predictions is seen within the errors: our results are nicely consistent with the Lattice QCD and chiral perturbation theory predictions. However, there are large discrepancies among the theoretical predictions on d$$_1^q(0)$$1q(0). Nevertheless, our prediction is in accord with the JLab data as well as with the results of the Lattice QCD, chiral perturbation theory and KM15-fit. Our fit functions well define most of the JLab data in the interval $$ Q^2\in [0,0.4]$$Q2∈[0,0.4] GeV$$^2 $$2, while the Lattice results suffer from large uncertainties in this region. As a by-product, some mechanical properties of the nucleon like the pressure and energy density at the center of nucleon as well as its mechanical radius are also calculated and their results are compared with other existing theoretical predictions.

scholarly journals A Guide to Light-Cone PDFs from Lattice QCD: An Overview of Approaches, Techniques, and Results

2019 ◽  
Vol 2019 ◽  
pp. 1-68 ◽  
Author(s):  
Krzysztof Cichy ◽  
Martha Constantinou
Keyword(s):  
Lattice Qcd ◽  
Cross Sections ◽  
Light Cone ◽  
Distribution Functions ◽  
Strong Interactions ◽  
Parton Distribution Functions ◽  
Hadronic Tensor ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
The Rich

Within the theory of Quantum Chromodynamics (QCD), the rich structure of hadrons can be quantitatively characterized, among others, using a basis of universal nonperturbative functions: parton distribution functions (PDFs), generalized parton distributions (GPDs), transverse momentum dependent parton distributions (TMDs), and distribution amplitudes (DAs). For more than half a century, there has been a joint experimental and theoretical effort to obtain these partonic functions. However, the complexity of the strong interactions has placed severe limitations, and first-principle information on these distributions was extracted mostly from their moments computed in Lattice QCD. Recently, breakthrough ideas changed the landscape and several approaches were proposed to access the distributions themselves on the lattice. In this paper, we review in considerable detail approaches directly related to partonic distributions. We highlight a recent idea proposed by X. Ji on extracting quasidistributions that spawned renewed interest in the whole field and sparked the largest amount of numerical studies within Lattice QCD. We discuss theoretical and practical developments, including challenges that had to be overcome, with some yet to be handled. We also review numerical results, including a discussion based on evolving understanding of the underlying concepts and the theoretical and practical progress. Particular attention is given to important aspects that validated the quasidistribution approach, such as renormalization, matching to light-cone distributions, and lattice techniques. In addition to a thorough discussion of quasidistributions, we consider other approaches: hadronic tensor, auxiliary quark methods, pseudodistributions, OPE without OPE, and good lattice cross-sections. In the last part of the paper, we provide a summary and prospects of the field, with emphasis on the necessary conditions to obtain results with controlled uncertainties.

scholarly journals Addendum to: Light-cone distribution amplitudes of pseudoscalar mesons from lattice QCD

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Gunnar S. Bali ◽  
◽  
Vladimir M. Braun ◽  
Simon Bürger ◽  
Meinulf Göckeler ◽  
...  
Keyword(s):  
Lattice Qcd ◽  
Light Cone ◽  
Pseudoscalar Mesons

Abstract We update our lattice determination of the two lowest Gegenbauer moments of the leading-twist pion and kaon light-cone distribution amplitudes [1]

scholarly journals Gluon structure function of a color dipole in the light-cone limit of lattice QCD

2009 ◽  
Vol 80 (7) ◽  
Author(s):  
D. Grünewald ◽  
E.-M. Ilgenfritz ◽  
H. J. Pirner
Keyword(s):  
Structure Function ◽  
Lattice Qcd ◽  
Light Cone ◽  
Color Dipole

scholarly journals Light-cone distribution amplitudes of octet baryons from lattice QCD

2019 ◽  
Vol 55 (7) ◽  
Author(s):  
Gunnar S. Bali ◽  
◽  
Vladimir M. Braun ◽  
Simon Bürger ◽  
Sara Collins ◽  
...  
Keyword(s):  
Lattice Qcd ◽  
Light Cone ◽  
Octet Baryons

scholarly journals Neural-network analysis of Parton Distribution Functions from Ioffe-time pseudodistributions

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Luigi Del Debbio ◽  
Tommaso Giani ◽  
Joseph Karpie ◽  
Kostas Orginos ◽  
Anatoly Radyushkin ◽  
...  
Keyword(s):  
Neural Network ◽  
Network Analysis ◽  
Lattice Qcd ◽  
Parton Distribution ◽  
Light Cone ◽  
Distribution Functions ◽  
Neural Network Analysis ◽  
Parton Distribution Functions ◽  
Taking Care

Abstract We extract two nonsinglet nucleon Parton Distribution Functions from lattice QCD data for reduced Ioffe-time pseudodistributions. We perform such analysis within the NNPDF framework, considering data coming from different lattice ensembles and dis- cussing in detail the treatment of the different source of systematics involved in the fit. We introduce a recipe for taking care of systematics and use it to perform our extraction of light-cone PDFs.

scholarly journals Impact of Scalar Leptoquarks on Heavy Baryonic Decays

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
K. Azizi ◽  
A. T. Olgun ◽  
Z. Tavukoğlu
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Lattice Qcd ◽  
Light Cone ◽  
Branching Ratio ◽  
Form Factors ◽  
Full Theory ◽  
The Standard Model ◽  
The Impact ◽  
Scalar Leptoquarks

We present a study on the impact of scalar leptoquarks on the semileptonic decays of Λb, Σb, and Ξb. To this end, we calculate the differential branching ratio and lepton forward-backward asymmetry defining the processes Λb→Λl+l-, Σb→Σl+l-, and Ξb→Ξl+l-, with l being μ or τ, using the form factors calculated via light cone QCD in full theory. In calculations, the errors of form factors are taken into account. We compare the results obtained in leptoquark model with those of the standard model as well as the existing lattice QCD predictions and experimental data.

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