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Full-Text Articles in Physics
Counting Linearly Polarized Gluons With Lattice Qcd, Shuai Zhao
Counting Linearly Polarized Gluons With Lattice Qcd, Shuai Zhao
Physics Faculty Publications
We outline an approach to calculate the transverse-momentum-dependent distribution of linearly polarized gluons inside an unpolarized hadron on the lattice with the help of large momentum effective theory. To achieve this purpose, we propose calculating a Euclidean version of the degree of polarization for a fast-moving hadron on the lattice, which is ultraviolet finite, and no soft function subtraction is needed. It indicates a practical way to explore the distribution of the linearly polarized gluons in a proton and the linearly polarized gluon effects in hadron collisions on the lattice.
Prospects For 𝛾*𝛾* → 𝜋𝜋 Via Lattice Qcd, Raúl Briceño, Andrew W. Jackura, Arkaitz Rodas, Juan V. Guerrero
Prospects For 𝛾*𝛾* → 𝜋𝜋 Via Lattice Qcd, Raúl Briceño, Andrew W. Jackura, Arkaitz Rodas, Juan V. Guerrero
Physics Faculty Publications
The 𝛾*𝛾* → 𝜋𝜋 scattering amplitude plays a key role in a wide range of phenomena, including understanding the inner structure of scalar resonances as well as constraining the hadronic contributions to the anomalous magnetic moment of the muon. In this work, we explain how the infinite-volume Minkowski amplitude can be constrained from finite-volume Euclidean correlation functions. The relationship between the finite-volume Euclidean correlation functions and the desired amplitude holds up to energies where 3𝜋 states can go on shell, and is exact up to exponentially small corrections that scale like 𝒪(e−m𝜋L), where L is the spatial extent …
Gluon Transverse-Momentum-Dependent Distributions From Large-Momentum Effective Theory, Ruilin Zhu, Yao Ji, Jian-Hui Zhang, Shuai Zhao
Gluon Transverse-Momentum-Dependent Distributions From Large-Momentum Effective Theory, Ruilin Zhu, Yao Ji, Jian-Hui Zhang, Shuai Zhao
Physics Faculty Publications
We demonstrate that gluon transverse-momentum-dependent parton distribution functions (TMDPDFs) can be extracted from lattice calculations of appropriate Euclidean correlations in large-momentum effective theory (LaMET). Based on perturbative calculations of gluon unpolarized and helicity TMDPDFs, we present a matching formula connecting them and their LaMET counterparts, where the latter are renormalized in a scheme facilitating lattice calculations and converted to the MS ¯ scheme. The hard matching kernel is given up to one-loop level. We also show that the perturbative result is independent of the prescription used for the pinch-pole singularity in the relevant correlations. Our results offer a guidance for …
Analytic Continuation Of The Relativistic Three-Particle Scattering Amplitudes, Sebastian M. Dawid, Md Habib E. Islam, Raúl A. Briceño
Analytic Continuation Of The Relativistic Three-Particle Scattering Amplitudes, Sebastian M. Dawid, Md Habib E. Islam, Raúl A. Briceño
Physics Faculty Publications
We investigate the relativistic scattering of three identical scalar bosons interacting via pair-wise interactions. Extending techniques from the nonrelativistic three-body scattering theory, we provide a detailed and general prescription for solving and analytically continuing integral equations describing the three-body reactions. We use these techniques to study a system with zero angular momenta described by a single scattering length leading to a bound state in a two-body subchannel. We obtain bound-state-particle and three-particle amplitudes in the previously unexplored kinematical regime; in particular, for real energies below elastic thresholds and complex energies in the physical and unphysical Riemann sheets. We extract positions …
Connecting Matrix Elements To Multi-Hadron Form-Factors, Andrew W. Jackura
Connecting Matrix Elements To Multi-Hadron Form-Factors, Andrew W. Jackura
Physics Faculty Publications
We discuss developments in calculating multi-hadron form-factors and transition processes via lattice QCD. Our primary tools are finite-volume scaling relations, which map spectra and matrix elements to the corresponding multi-hadron infinite-volume amplitudes. We focus on two hadron processes probed by an external current, and provide various checks on the finite-volume formalism in the limiting cases of perturbative interactions and systems forming a bound state. By studying model-independent properties of the infinite-volume amplitudes, we are able to rigorously define form-factors of resonances.
Consistency Checks For Two-Body Finite-Volume Matrix Elements: Conserved Currents And Bound States, Raúl A. Briceño, Christopher J. Monahan
Consistency Checks For Two-Body Finite-Volume Matrix Elements: Conserved Currents And Bound States, Raúl A. Briceño, Christopher J. Monahan
Physics Faculty Publications
We present a model-independent framework to determine finite-volume corrections of matrix elements of spatially separated current-current operators. We define these matrix elements in terms of Compton-like amplitudes, i.e., amplitudes coupling single-particle states via two current insertions. We show that the infrared behavior of these matrix elements is dominated by the single-particle pole, which is approximated by the elastic form factors of the lowest-lying hadron. Therefore, given lattice data on the relevant elastic form factors, the finite-volume effects can be estimated nonperturbatively and without recourse to effective field theories. For illustration purposes, we investigate the implications of the proposed formalism for …
Role Of Boundary Conditions In Quantum Computations Of Scattering Observables, Raúl A. Briceño, Juan V. Guerrero, Maxwell T. Hansen, Alexandru M. Sturzu
Role Of Boundary Conditions In Quantum Computations Of Scattering Observables, Raúl A. Briceño, Juan V. Guerrero, Maxwell T. Hansen, Alexandru M. Sturzu
Physics Faculty Publications
Quantum computing may offer the opportunity to simulate strongly interacting field theories, such as quantum chromodynamics, with physical time evolution. This would give access to Minkowski-signature correlators, in contrast to the Euclidean calculations routinely performed at present. However, as with present-day calculations, quantum computation strategies still require the restriction to a finite system size, including a finite, usually periodic, spatial volume. In this work, we investigate the consequences of this in the extraction of hadronic and Compton-like scattering amplitudes. Using the framework presented in Briceno et al. [Phys. Rev. D 101, 014509 (2020)], we estimate the volume effects for various …
Constraining 1 + 𝒥 → 2 Coupled-Channel Amplitudes In A Finite Volume, Raúl A. Briceño, Jozef J. Dudek, Luka Leskovec
Constraining 1 + 𝒥 → 2 Coupled-Channel Amplitudes In A Finite Volume, Raúl A. Briceño, Jozef J. Dudek, Luka Leskovec
Physics Faculty Publications
Whether one is interested in accessing the excited spectrum of hadrons or testing the standard model of particle physics, electroweak transition processes involving multihadron channels in the final state play an important role in a variety of experiments. Presently the primary theoretical tool with which one can study such reactions is lattice QCD, which is defined in a finite spacetime volume. In this work, we investigate the feasibility of implementing existing finite-volume formalism in realistic lattice QCD calculation of reactions in which a stable hadron can transition to one of several two-hadron channels under the action of an external current. …
The Continuum And Leading Twist Limits Of Parton Distribution Functions In Lattice Qcd, Joseph Karpie, Kostas Orginos, Anatoly Radyushkin, Savvas Zafeiropoulos, For The Hadstruc Collaboration
The Continuum And Leading Twist Limits Of Parton Distribution Functions In Lattice Qcd, Joseph Karpie, Kostas Orginos, Anatoly Radyushkin, Savvas Zafeiropoulos, For The Hadstruc Collaboration
Physics Faculty Publications
In this study, we present continuum limit results for the unpolarized parton distribution function of the nucleon computed in lattice QCD. This study is the first continuum limit using the pseudo-PDF approach with Short Distance Factorization for factorizing lattice QCD calculable matrix elements. Our findings are also compared with the pertinent phenomenological determinations. Inter alia, we are employing the summation Generalized Eigenvalue Problem (sGEVP) technique in order to optimize our control over the excited state contamination which can be one of the most serious systematic errors in this type of calculations. A crucial novel ingredient of our analysis is the …
Unpolarized Gluon Distribution In The Nucleon From Lattice Quantum Chromodynamics, Tanjib Khan, Raza Sabbir Sufian, Joseph Karpie, Christopher J. Monahan, Colin Egerer, Bálint Joó, Wayne Morris, Kostas Orginos, Anatoly Radyushkin, David G. Richards, Eloy Romero, Savvas Zafeiropoulos, On Behalf Of The Hadstruc Collaboration
Unpolarized Gluon Distribution In The Nucleon From Lattice Quantum Chromodynamics, Tanjib Khan, Raza Sabbir Sufian, Joseph Karpie, Christopher J. Monahan, Colin Egerer, Bálint Joó, Wayne Morris, Kostas Orginos, Anatoly Radyushkin, David G. Richards, Eloy Romero, Savvas Zafeiropoulos, On Behalf Of The Hadstruc Collaboration
Physics Faculty Publications
In this study, we present a determination of the unpolarized gluon Ioffe-time distribution in the nucleon from a first principles lattice quantum chromodynamics calculation. We carry out the lattice calculation on a 323 × 64 ensemble with a pion mass of 358 MeV and lattice spacing of 0.094 fm. We construct the nucleon interpolating fields using the distillation technique, flow the gauge fields using the gradient flow, and solve the summed generalized eigenvalue problem to determine the gluonic matrix elements. Combining these techniques allows us to provide a statistically well-controlled Ioffe-time distribution and unpolarized gluon parton distribution function. We …
Long-Range Electroweak Amplitudes Of Single Hadrons From Euclidean Finite-Volume Correlation Functions, Raúl A. Briceño, Zohreh Davoudi, Maxwell T. Hansen, Matthias R. Schindler, Alessandro Baroni
Long-Range Electroweak Amplitudes Of Single Hadrons From Euclidean Finite-Volume Correlation Functions, Raúl A. Briceño, Zohreh Davoudi, Maxwell T. Hansen, Matthias R. Schindler, Alessandro Baroni
Physics Faculty Publications
A relation is presented between single-hadron long-range matrix elements defined in a finite Euclidean spacetime and the corresponding infinite-volume Minkowski amplitudes. This relation is valid in the kinematic region where any number of two-hadron states can simultaneously go on shell, so that the effects of strongly coupled intermediate channels are included. These channels can consist of nonidentical particles with arbitrary intrinsic spins. The result accommodates general Lorentz structures as well as nonzero momentum transfer for the two external currents inserted between the single-hadron states. The formalism, therefore, generalizes the work by Christ et al. [Phys. Rev. D 91, 114510 …
Numerical Exploration Of Three Relativistic Particles In A Finite Volume Including Two-Particle Resonances And Bound States, Fernando Romero-López, Stephen R. Sharpe, Tyler D. Blanton, Raúl A. Briceño, Maxwell T. Hansen
Numerical Exploration Of Three Relativistic Particles In A Finite Volume Including Two-Particle Resonances And Bound States, Fernando Romero-López, Stephen R. Sharpe, Tyler D. Blanton, Raúl A. Briceño, Maxwell T. Hansen
Physics Faculty Publications
In this work, we use an extension of the quantization condition, given in ref. [1], to numerically explore the finite-volume spectrum of three relativistic particles, in the case that two-particle subsets are either resonant or bound. The original form of the relativistic three-particle quantization condition was derived under a technical assumption on the two-particle K matrix that required the absence of two-particle bound states or narrow two-particle resonances. Here we describe how this restriction can be lifted in a simple way using the freedom in the definition of the K-matrix-like quantity that enters the quantization condition. With this in hand, …
Finite Volume Matrix Elements Of Two-Body States, Alessandro Baroni, Raúl A. Briceño, Maxwell T. Hansen, Filipe G. Ortega-Gama
Finite Volume Matrix Elements Of Two-Body States, Alessandro Baroni, Raúl A. Briceño, Maxwell T. Hansen, Filipe G. Ortega-Gama
Physics Faculty Publications
In this talk, we present a framework for studying structural information of resonances and bound states coupling to two-hadron scattering states. This makes use of a recently proposed finite-volume formalism to determine a class of observables that are experimentally inaccessible but can be accessed via lattice QCD. In particular, we shown that finite-volume two-body matrix elements with one current insertion can be directly related to scattering amplitudes coupling to the external current. For two-hadron systems with resonances or bound states, one can extract the corresponding form factors of these from the energy-dependence of the amplitudes.
Isoscalar Ππ; Kk; Ηη Scattering And The Σ; F0; F2 Mesons From Qcd, Raul A. Briceño, Jozef J. Dudek, Robert G. Edwards, David J. Wilson
Isoscalar Ππ; Kk; Ηη Scattering And The Σ; F0; F2 Mesons From Qcd, Raul A. Briceño, Jozef J. Dudek, Robert G. Edwards, David J. Wilson
Physics Faculty Publications
We present the first lattice QCD study of coupled isoscalar ππ;K ¯K; ηη S- and D-wave scattering extracted from discrete finite-volume spectra computed on lattices which have a value of the light quark mass corresponding to mπ ∼ 391 MeV. In the JP = 0+ sector we find analogues of the experimental σ and f0 (980) states, where the σ appears as a stable bound-state below ππ threshold, and, similar to what is seen in experiment, the f0 (980) manifests itself as a dip in the ππ cross section in the vicinity of the …
Pion Distribution Amplitude And Quasidistributions, A. V. Radyushkin
Pion Distribution Amplitude And Quasidistributions, A. V. Radyushkin
Physics Faculty Publications
We extend our analysis of quasidistributions onto the pion distribution amplitude. Using the formalism of parton virtuality distribution amplitudes, we establish a connection between the pion transverse momentum dependent distribution amplitude Ψ(x, k2⊥) and the pion quasidistribution amplitude (QDA) Qπ(y, p3). We build models for the QDAs from the virtuality-distribution-amplitude-based models for soft transverse momentum dependent distribution amplitudes, and analyze the p3 dependence of the resulting QDAs. As there are many models claimed to describe the primordial shape of the pion distribution amplitude, we present the p3-evolution …
Nonperturbative Evolution Of Parton Quasi-Distributions, A. V. Radyushkin
Nonperturbative Evolution Of Parton Quasi-Distributions, A. V. Radyushkin
Physics Faculty Publications
Using the formalism of parton virtuality distribution functions (VDFs) we establish a connection between the transverse momentum dependent distributions (TMDs) F(x,k2⊥) and quasi-distributions (PQDs) Q(y,p3) introduced recently by X. Ji for lattice QCD extraction of parton distributions f(x). We build models for PQDs from the VDF-based models for soft TMDs, and analyze the p3 dependence of the resulting PQDs. We observe a strong nonperturbative evolution of PQDs for small and moderately large values of p3 reflecting the transverse momentum dependence of TMDs. Thus, the study of PQDs on the lattice …
Isoscalar 𝜋𝜋 Scattering And The Σ Meson Resonance From Qcd, Raúl A. Briceño, Jozef J. Dudek, Robert G. Edwards, David J. Wilson
Isoscalar 𝜋𝜋 Scattering And The Σ Meson Resonance From Qcd, Raúl A. Briceño, Jozef J. Dudek, Robert G. Edwards, David J. Wilson
Physics Faculty Publications
We present for the first time a determination of the energy dependence of the isoscalar ππ elastic scattering phase shift within a first-principles numerical lattice approach to QCD. Hadronic correlation functions are computed including all required quark propagation diagrams, and from these the discrete spectrum of states in the finite volume defined by the lattice boundary is extracted. From the volume dependence of the spectrum, we obtain the S-wave phase shift up to the KK¯ threshold. Calculations are performed at two values of the u, d quark mass corresponding to mπ=236,391 MeV, and the resulting amplitudes …
Role Of The Euclidean Signature In Lattice Calculations Of Quasidistributions And Other Nonlocal Matrix Elements, Raúl A. Briceño, Maxwell T. Hansen, Christopher J. Monahan
Role Of The Euclidean Signature In Lattice Calculations Of Quasidistributions And Other Nonlocal Matrix Elements, Raúl A. Briceño, Maxwell T. Hansen, Christopher J. Monahan
Physics Faculty Publications
Lattice quantum chromodynamics (QCD) provides the only known systematic, nonperturbative method for first-principles calculations of nucleon structure. However, for quantities such as light-front parton distribution functions (PDFs) and generalized parton distributions (GPDs), the restriction to Euclidean time prevents direct calculation of the desired observable. Recently, progress has been made in relating these quantities to matrix elements of spatially nonlocal, zero-time operators, referred to as quasidistributions. Still, even for these time-independent matrix elements, potential subtleties have been identified in the role of the Euclidean signature. In this work, we investigate the analytic behavior of spatially nonlocal correlation functions and demonstrate that …
Relativistic, Model-Independent, Multichannel 2 → 2 Transition Amplitudes In A Finite Volume, Raúl A. Briceño, Maxwell T. Hansen
Relativistic, Model-Independent, Multichannel 2 → 2 Transition Amplitudes In A Finite Volume, Raúl A. Briceño, Maxwell T. Hansen
Physics Faculty Publications
We derive formalism for determining 2+𝓙 → 2 infinite-volume transition amplitudes from finite-volume matrix elements. Specifically, we present a relativistic, model-independent relation between finite-volume matrix elements of external currents and the physically observable infinite-volume matrix elements involving two-particle asymptotic states. The result presented holds for states composed of two scalar bosons. These can be identical or nonidentical and, in the latter case, can be either degenerate or nondegenerate. We further accommodate any number of strongly coupled two-scalar channels. This formalism will, for example, allow future lattice QCD calculations of the ρ-meson form factor, in which the unstable nature of …
𝜋𝜋 → 𝜋𝛾* Amplitude And The Resonant 𝜌 → 𝜋𝛾* Transition From Lattice Qcd, Raúl A. Briceño, Jozef J. Dudek, Robert G. Edwards, Christian J. Shultz, Christopher E. Thomas, David J. Wilson
𝜋𝜋 → 𝜋𝛾* Amplitude And The Resonant 𝜌 → 𝜋𝛾* Transition From Lattice Qcd, Raúl A. Briceño, Jozef J. Dudek, Robert G. Edwards, Christian J. Shultz, Christopher E. Thomas, David J. Wilson
Physics Faculty Publications
We present a determination of the P-wave 𝜋𝜋 → 𝜋𝛾⋆ transition amplitude from lattice quantum chromodynamics. Matrix elements of the vector current in a finite volume are extracted from three-point correlation functions, and from these we determine the infinite-volume amplitude using a generalization of the Lellouch-Lüscher formalism. We determine the amplitude for a range of discrete values of the 𝜋𝜋 energy and virtuality of the photon and observe the expected dynamical enhancement due to the ρ resonance. Describing the energy dependence of the amplitude, we are able to analytically continue into the complex energy plane and from the residue …
Meson Photo-Couplings From Lattice Quantum Chromodynamics, Christian J. P. Shultz
Meson Photo-Couplings From Lattice Quantum Chromodynamics, Christian J. P. Shultz
Physics Theses & Dissertations
We explore the calculation of three-point functions featuring a vector current insertion in lattice Quantum Chromodynamics. These three-point functions, in general, contain information about many radiative transition matrix elements simultaneously. We develop and implement the technology necessary to isolate a single matrix element via the use of optimized operators, operators designed to interpolate a single meson eigenstate, which are constructed as variationally optimized linear combination of meson interpolating fields within a large basis. In order to frame the results we also explore some well known phenomenology arising within the context of the constituent quark model before transitioning to a lattice …
Negative-Parity Baryon Masses Using An O(A)-Improved Fermion Action, M. Göckeler, R. Horsley, D. Pleiter, P. E. L. Rakow, G. Schierholz, C. M. Maynard, D. G. Richards
Negative-Parity Baryon Masses Using An O(A)-Improved Fermion Action, M. Göckeler, R. Horsley, D. Pleiter, P. E. L. Rakow, G. Schierholz, C. M. Maynard, D. G. Richards
Physics Faculty Publications
We present a calculation of the mass of the lowest-lying negative-parity J=1/2− state in quenched QCD. Results are obtained using a non-perturbatively O(a)-improved clover fermion action, and a splitting is found between the mass of the nucleon, and its parity partner. The calculation is performed on two lattice volumes and at three lattice spacings, enabling a study of both finite-volume and finite lattice-spacing uncertainties. A comparison is made with results obtained using the unimproved Wilson fermion action.