Nuclear Theory·nucl-th

Tuesday·February 7, 2023

8 papers—4 primary·4 cross-listed

05
Rescattering effects in nucleon-to-meson form factors and application to tau-lepton-induced proton decay
Andreas Crivellin🇨🇭 · Martin Hoferichter🇨🇭
Nucleon decays put extremely stringent bounds on baryon-number-violating interactions. However, in case the corresponding operators involve only $τ$ leptons, the direct two-body decays, e.g., $p \to π^{0} τ^{+}$ , are kinematically not allowed and nucleon decay can only proceed via an off-shell $τ$ , leading to $p \to π^{0} ℓ^{+} ν_{ℓ} ν ˉ_{τ}$ . To calculate such processes, the momentum dependence of the form factors for nucleon-to-meson transitions, which describe the hadronization of the underlying process at the quark level, is needed. In this work, we point out new isospin and Fierz relations among such proton-kaon matrix elements and calculate the momentum dependence of the nucleon-to-meson form factors from the universal final-state interactions in terms of pion-nucleon or kaon-nucleon scattering phase shifts. We use these results to derive novel limits on the Wilson coefficients of the baryon-number-violating dimension- $6$ operators involving a $τ$ lepton, which were previously unconstrained.
↳ hep-phhep-exhep-latnucl-thPLB(2023)·14 citations
06
Opportunities for Fundamental Physics Research with Radioactive Molecules
Gordon Arrowsmith-Kron🇺🇸 · Michail Athanasakis-Kaklamanakis🇨🇭 · Mia Au🇨🇭 · Jochen Ballof🇨🇭 · Robert Berger🇩🇪 · Anastasia Borschevsky🇳🇱 · Alexander A. Breier🇩🇪 · Fritz Buchinger🇨🇦 · Dmitry Budker🇩🇪 · Luke Caldwell🇺🇸 · Christopher Charles🇨🇦 · Nike Dattani and 50 other authors
Molecules containing short-lived, radioactive nuclei are uniquely positioned to enable a wide range of scientific discoveries in the areas of fundamental symmetries, astrophysics, nuclear structure, and chemistry. Recent advances in the ability to create, cool, and control complex molecules down to the quantum level, along with recent and upcoming advances in radioactive species production at several facilities around the world, create a compelling opportunity to coordinate and combine these efforts to bring precision measurement and control to molecules containing extreme nuclei. In this manuscript, we review the scientific case for studying radioactive molecules, discuss recent atomic, molecular, nuclear, astrophysical, and chemical advances which provide the foundation for their study, describe the facilities where these species are and will be produced, and provide an outlook for the future of this nascent field.
↳ nucl-exnucl-thphysics.atom-phRept.Prog.Phys.(2024)·81 citations
07
Viscous QCD medium effects on the bottom quark transport coefficients
Adiba Shaikh🇮🇳 · Sadhana Dash🇮🇳 · Basanta K. Nandi🇮🇳
The bottom quark transport coefficients, i.e., drag and diffusion coefficients, have been studied for the collisional and soft gluon radiative processes within the viscous QCD medium. The thermal medium effects are incorporated using the effective fugacity quasiparticle model (EQPM). Both the shear and bulk viscous effects at leading order are embedded through the near-equilibrium distribution functions of the quark-gluon plasma (QGP) constituent quasiparticles. The transport coefficients' dependence on the bottom quark's initial momentum and QGP temperature has been investigated. The relative dominance of the radiative over the collisional process for the bottom quark seems to occur at a higher initial momentum compared to that of the charm quark. In contrast, the effect of the viscous corrections seems to be more for the charm quark.
↳ hep-phnucl-thEPJC(2023)·6 citations
08
Cross section measurement of the 144Sm(alpha,n)147Gd reaction for studying the alpha-nucleus optical potential at astrophysical energies
Gy. Gyürky · P. Mohr · A. Angyal · Z. Halász · G.G. Kiss · Zs. Mátyus · T.N. Szegedi · T. Szücs · Zs. Fülöp
Nuclear reactions involving alpha particles play an important role in various astrophysical processes such as the gamma-process of heavy element nucleosynthesis. The poorly known low-energy alpha-nucleus optical (AOMP) potential is a key parameter to estimate the rates of these reactions. The AOMP can be tested by measuring the cross section of alpha-scattering as well as alpha-induced reactions. Low energy elastic alpha-scattering on 144Sm has recently been measured with high precision. The aim of the present work was to complement that work by measuring the (a,n) cross sections on 144Sm at low energies. The experimental data shall be used to constrain the AOMP. From this potential the 144Sm(a,g)148Gd reaction rate can be derived with reduced uncertainties. The 144Sm(a,n)147Gd reaction was studied by bombarding Sm targets with alpha-beams provided by the cyclotron accelerator of Atomki. The cross section was determined using the activation method. The gamma-radiation following the decay of the 147Gd reaction product was measured with a HPGe detector. The experimental data are analyzed within the statistical model. The cross section was measured in the alpha-energy range between 13 and 20 MeV in 1 MeV steps, i.e., from close above the (a,n) threshold. The results were compared with statistical model calculations using various approaches and parametrizations for the AOMP, and excellent agreement was obtained for two recent potentials. However, these potentials cannot reproduce literature data for the 144Sm(a,g)148Gd reaction with the same accuracy. Constraints for the AOMP were derived from an analysis of the new 144Sm(a,n)147Gd data and literature data for 144Sm(a,g)148Gd. These constraints enable a determination of the reaction rate of the 144Sm(a,g)148Gd reaction with significantly reduced uncertainties of less than a factor of two.
↳ nucl-exastro-ph.SRnucl-thPRC(2023)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE

Rescattering effects in nucleon-to-meson form factors and application to tau-lepton-induced proton decay

Opportunities for Fundamental Physics Research with Radioactive Molecules

Viscous QCD medium effects on the bottom quark transport coefficients

Cross section measurement of the 144Sm(alpha,n)147Gd reaction for studying the alpha-nucleus optical potential at astrophysical energies

Affiliations