Nuclear Theory·nucl-th

Tuesday·October 3, 2023

11 papers—5 primary·6 cross-listed

06
Zemach and Friar radii of the proton and neutron from lattice QCD
Dalibor Djukanovic🇩🇪 · Georg von Hippel🇩🇪 · Harvey B. Meyer🇩🇪 · Konstantin Ottnad🇩🇪 · Miguel Salg🇩🇪 · Hartmut Wittig🇩🇪
We present the first lattice-QCD result for the Zemach and Friar radii of the proton and neutron. Our calculation includes both quark-connected and -disconnected diagrams and assesses all sources of systematic uncertainties arising from excited-state contributions, finite-volume effects and the continuum extrapolation. At the physical point, we obtain for the proton $r_{Z}^{p} = (1.013 \pm 0.010 (stat) \pm 0.012 (syst)) fm$ and $r_{F}^{p} = (1.301 \pm 0.012 (stat) \pm 0.014 (syst)) fm$ . These numbers suggest small values of the Zemach and Friar radii of the proton, but are compatible with most of the experimental studies.
↳ hep-lathep-phnucl-thPRD(2024)·9 citations
07
Quantum Field Theory in Large N Wonderland: Three Lectures
Paul Romatschke🇺🇸
In these lecture notes, I review how to use large N techniques to solve quantum field theories in various dimensions. In particular, the case of N-dimensional quantum mechanics, non-relativistic cold and dense neutron matter, and scalar field theory in four dimensions are covered. A recurring theme is that large N solutions are fully non-perturbative, and can be used to reliably access quantum field theory for parameter regions where weak-coupling expansions simply fail.
↳ hep-thhep-phnucl-thActa Phys.Polon.B(2024)·18 citations
08
Scalar boson emission from a magnetized relativistic plasma
Jorge Jaber-Urquiza🇲🇽 · Igor A. Shovkovy🇺🇸
We investigate the differential emission rate of neutral scalar bosons from a highly magnetized relativistic plasma. We show that three processes contribute at the leading order: particle splitting ( $ψ \to ψ + ϕ$ ), antiparticle splitting ( $ψ ˉ \to ψ ˉ + ϕ$ ), and particle-antiparticle annihilation ( $ψ + ψ ˉ \to ϕ$ ). This is in contrast to the scenario with zero magnetic field, where only the annihilation processes contribute to boson production. We examine the impact of Landau-level quantization on the energy dependence of the rate and investigate the angular distribution of emitted scalar bosons. The differential rate resulting from both (anti)particle splitting and annihilation processes are typically suppressed in the direction of the magnetic field and enhanced in perpendicular directions. Overall, the background magnetic field significantly amplifies the total emission rate. We speculate that our model calculations provide valuable theoretical insights with potentially important applications.
↳ hep-phhep-thnucl-thPRD(2023)·5 citations
09
Multibaryon configurations in a simple chromomagnetic model
Aaron Park🇰🇷
In this work, we study the multibaryon configurations in a simple chromomagnetic model. We first construct the wave function of the multibaryon states using the multiquark configuration. We consider all possible quantum numbers assuming the spatial part of the wave function to be totally symmetric. Then, we calculate the color-spin factors for tetrabaryons, pentabaryons and hexabaryons in the flavor SU(3) breaking case.
↳ hep-phnucl-thPRD(2024)·0 citations
10
Gluon PDF of the proton using twisted mass fermions
Joseph Delmar🇺🇸 · Constantia Alexandrou🇨🇾 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Kyriakos Hadjiyiannakou🇨🇾
In this paper, we present lattice QCD results for the $x$ -dependence of the unpolarized gluon PDF for the proton. We use one ensemble of $N_{f} = 2 + 1 + 1$ maximally twisted mass fermions with a clover improvement, and the Iwasaki improved gluon action. The quark masses are tuned to produce a pion with a mass of 260 MeV. The ensemble has a lattice spacing of $a = 0.093$ fm and a spatial extent of 3 fm. We employ the pseudo-distribution approach, which relies on matrix elements of non-local operators that couple to momentum-boosted hadrons. In this work, we use five values of the momentum boost between 0 and 1.67 GeV. The gluon field strength tensors of the non-local operator are connected with straight Wilson lines of varying length $z$ . The light-cone Ioffe time distribution (ITD) is extracted utilizing data with $z$ up to 0.56 fm and a quadratic parametrization in terms of the Ioffe time at fixed values of $z$ . We explore systematic effects, such as the effect of the stout smearing for the gluon operator, excited states effects, and the dependence on the maximum value of $z$ entering the fits to obtain the gluon PDF. Also, for the first time, the mixing with the quark singlet PDFs is eliminated using matrix elements with non-local quark operators that were previously analyzed within the quasi-PDF framework on the same ensemble. Here, we expand the data set for the quark singlet and reanalyze within the pseudo-PDFs method eliminating the corresponding mixing in the gluon PDF.
↳ hep-lathep-exhep-phnucl-thPRD(2023)·33 citations
11
Broadening of particle distributions in electron- and (anti)neutrino-nucleus scattering from QED interactions
Oleksandr Tomalak🇺🇸 · Ivan Vitev🇺🇸
Proper interpretation of past, current, and future data on lepton-nucleus reactions requires a clear separation between quantum electrodynamics (QED) and strong interaction effects inside the nucleus. First studies of QED in-medium lepton dynamics have set a theoretical framework to derive electron-nucleus and (anti)neutrino-nucleus cross-section corrections. We employ this approach to quantitatively compute the effects of Glauber photon-mediated multiple re-scattering within the nuclear medium. We find that the relativistic charged lepton acquires momentum of order $10 MeV$ transverse to its direction of propagation inside the nucleus. This broadening sizably deflects expected electron tracks and suppresses scattering cross sections. Precise extraction of the nucleon and nuclear structure by electron and muon probes should, thus, take the QED nuclear medium angular redistribution of particles into account. Our results further show that the associated effects in (anti)neutrino-nucleus scattering with measured final-lepton energy are significant only at the kinematical endpoints.
↳ hep-phhep-exnucl-exnucl-thPRD(2023)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE

Zemach and Friar radii of the proton and neutron from lattice QCD

Quantum Field Theory in Large N Wonderland: Three Lectures

Scalar boson emission from a magnetized relativistic plasma

Multibaryon configurations in a simple chromomagnetic model

Gluon PDF of the proton using twisted mass fermions

Broadening of particle distributions in electron- and (anti)neutrino-nucleus scattering from QED interactions

Affiliations