Nuclear Theory·nucl-th

Wednesday·September 5, 2018

23 papers—13 primary·10 cross-listed

14
Theoretical perspective for the future experiments on parton densities
S. Kumano (KEK/J-PARC)🇯🇵
I explain the current status of parton-distribution-function (PDF) studies and future experimental prospects on their determinations. First, unpolarized PDFs of the nucleon are introduced as a field of precision QCD physics including higher-order $α_{s}$ corrections. Second, nuclear PDFs and polarized nucleonic PDFs are discussed. Third, the determination of fragmentation functions is explained. Forth, the three-dimensional (3D) structure functions are discussed in connection with the origin of the nucleon spin and gravitational form factors of hadrons. By the 3D structure functions, gravitational sources and the origin of nucleon mass could be clarified in the microscopic level of quarks and gluons. Furthermore, 3D structure studies of hadrons could be used for clarifying internal structure of exotic hadron candidates, nuclear composition of ultra-high-energy cosmic rays, and color-entanglement phenomena. The PDF field will be developed further along with progress in other fields of science.
↳ hep-phhep-exhep-latnucl-ex+1PoS(2018)·3 citations
15
Meson correlation functions at high temperature QCD: $S U (2)_{C S}$ symmetry vs. free quarks
C. Rohrhofer🇦🇹 · Y. Aoki🇯🇵 · G. Cossu🇬🇧 · L. Ya. Glozman🇦🇹 · S. Hashimoto🇯🇵 · S. Prelovsek🇸🇮
We report on the progress of understanding spatial correlation functions in high temperature QCD. We study isovector meson operators in $N_{f} = 2$ QCD using domain-wall fermions on lattices of $N_{s} = 32$ and different quark masses. It has previously been found that at $\sim 2 T_{c}$ these observables are not only chirally symmetric but in addition approximately $S U (2)_{C S}$ and $S U (4)$ symmetric. In this study we increase the temperature up to $5 T_{c}$ and can identify convergence towards an asymptotically free scenario at very high temperatures.
↳ hep-lathep-phhep-thnucl-thPoS(2018)·5 citations
16
Neutron-antineutron oscillations from lattice QCD
Enrico Rinaldi🇺🇸 · Sergey Syritsyn🇺🇸 · Michael L. Wagman🇺🇸 · Michael I. Buchoff🇺🇸 · Chris Schroeder🇺🇸 · Joseph Wasem🇺🇸
Fundamental symmetry tests of baryon number violation in low-energy experiments can probe beyond the Standard Model (BSM) explanations of the matter-antimatter asymmetry of the universe. Neutron-antineutron oscillations are predicted to be a signature of many baryogenesis mechanisms involving low-scale baryon number violation. This work presents first-principles calculations of neutron-antineutron matrix elements needed to accurately connect measurements of the neutron-antineutron oscillation rate to constraints on $∣Δ B ∣ = 2$ baryon number violation in BSM theories. Several important systematic uncertainties are controlled by using a state-of-the-art lattice gauge field ensemble with physical quark masses and approximate chiral symmetry, performing nonperturbative renormalization with perturbative matching to the $MS$ scheme, and studying excited state effects in two-state fits. Phenomenological implications are highlighted by comparing expected bounds from proposed neutron-antineutron oscillation experiments to predictions of a specific model of post-sphaleron baryogenesis. Quantum chromodynamics is found to predict at least an order of magnitude more events in neutron-antineutron oscillation experiments than previous estimates based on the "MIT bag model" for fixed BSM parameters. Lattice artifacts and other systematic uncertainties that are not controlled in this pioneering calculation are not expected to significantly change this conclusion.
↳ hep-lathep-phnucl-thPRL(2019)·45 citations
17
Relating hadronic CP-violation to higher-twist distributions
Chien-Yeah Seng🇨🇳
The nucleon sigma term of the isoscalar and isovector quark chromo-magnetic dipole moments are essential inputs for the determination of the CP-odd pion-nucleon couplings induced by quark chromo-electric dipole moments. We demonstrate that the former can be mapped to the third moment of the nucleon twist-three chiral-odd distribution functions $e^{q} (x)$ which are in principle measurable in semi-inclusive deep inelastic scattering processes. We perform a survey on existing model calculations as well as experimental data on $e^{u} (x) + e^{d} (x)$ and derive a predicted range for the isoscalar chromo-magnetic dipole moment sigma term.
↳ hep-phhep-exnucl-thPRL(2019)·19 citations
18
$η^{'}$ and $η$ mesons at high T when the U_A(1) and chiral symmetry breaking are tied
Davor Horvatić🇭🇷 · Dalibor Kekez🇭🇷 · Dubravko Klabučar🇭🇷
The approach to the eta'-eta complex employing chirally well-behaved quark-antiquark bound states and incorporating the non-Abelian axial anomaly of QCD through the generalization of the Witten-Veneziano relation, is extended to finite temperatures. Employing the chiral condensate has led to a sharp chiral and U_A(1) symmetry restoration, but with the condensates of quarks with realistic explicit chiral symmetry breaking, which exhibit a smooth, crossover chiral symmetry restoration in qualitative agreement with lattice QCD results, we get a crossover U_A(1) transition, with smooth and gradual melting of anomalous mass contributions. This way we obtain a substantial drop of the eta' mass around the chiral transition temperature, but no eta mass drop. This is consistent with the present empirical evidence.
↳ hep-phnucl-thPRD(2019)·20 citations
19
FRIB and the GW170817 Kilonova
A. Aprahamian🇺🇸 · R. Surman🇺🇸 · A. Frebel🇺🇸 · G.C. McLaughlin🇺🇸 · A. Arcones🇩🇪 · A.B. Balantekin🇺🇸 · J. Barnes🇺🇸 · Timothy C. Beers🇺🇸 · Erika M. Holmbeck🇺🇸 · Jinmi Yoon🇺🇸 · Maxime Brodeur🇺🇸 · T.M. Sprouse🇺🇸 and 36 other authors
In July 2018 an FRIB Theory Alliance program was held on the implications of GW170817 and its associated kilonova for r-process nucleosynthesis. Topics of discussion included the astrophysical and nuclear physics uncertainties in the interpretation of the GW170817 kilonova, what we can learn about the astrophysical site or sites of the r process from this event, and the advances in nuclear experiment and theory most crucial to pursue in light of the new data. Here we compile a selection of scientific contributions to the workshop, broadly representative of progress in r-process studies since the GW170817 event.
↳ astro-ph.HEastro-ph.SRnucl-th13 citations
20
Women Scientists Who Made Nuclear Astrophysics
C. V. Hampton🇺🇸 · M. Lugaro🇭🇺 · P. Papakonstantinou🇰🇷 · P. G. Isar🇷🇴 · B. Nordström🇩🇰 · N. Özkan🇹🇷 · M. Aliotta🇬🇧 · A. Ćiprijanović🇷🇸 · S. Curtis🇺🇸 · M. Di Criscienzo🇮🇹 · J. den Hartogh🇭🇺 · A. S. Font🇬🇧 and 15 other authors
Female role models reduce the impact on women of stereotype threat, i.e., of being at risk of conforming to a negative stereotype about one's social, gender, or racial group. This can lead women scientists to underperform or to leave their scientific career because of negative stereotypes such as, not being as talented or as interested in science as men. Sadly, history rarely provides role models for women scientists; instead, it often renders these women invisible. In response to this situation, we present a selection of twelve outstanding women who helped to develop nuclear astrophysics.
↳ physics.hist-phastro-ph.EPastro-ph.GAastro-ph.HE+3Springer Proc.Phys.(2019)·0 citations
21
Bound state formation in the $D D K$ system
A. Martinez Torres🇧🇷 · K. P. Khemchandani🇨🇳 · Li-Sheng Geng🇨🇳
We study the $D D K$ system in a coupled channel approach, by including $D D_{s} η$ and $D D_{s} π$ , and find that the dynamics involved in the system forms a bound state with isospin $1/2$ and mass $4140$ MeV when one of the $D K$ pair is resonating in isospin 0, forming the $D_{s 0}^{*} (2317)$ . The state can be interpreted as a $D D_{s 0}^{*} (2317)$ molecule like state with exotic quantum numbers: doubly charged, doubly charmed, and with single strangeness.
↳ hep-phnucl-thPRD(2019)·42 citations
22
Effects of neutrino mixing upon electron fraction in core collapse supernovae
M.M. Saez🇦🇷 · M.E. Mosquera🇦🇷 · O. Civitarese🇦🇷
The inclusion of massive neutrinos affects the cross sections involved in the formation of heavy nuclei, modifying their abundances. Rapid neutron capture processes (r-process) are often associated with explosive events such as core-collapse supernovae. In this work we study the effects of active and sterile neutrino oscillations and interactions, upon the calculation of neutrino fluxes, the baryonic density and the electron fraction of the material. We have considered two different initial distribution functions of the neutrinos and different combinations of mixing parameters (including {\theta} 34 = 0). We use the formalism of density matrices for the calculations and included the effects of neutrino oscillations, interactions with matter and self-neutrino interactions. We found that the interactions of the neutrinos with matter and with themselves change the electron fraction, affecting the onset of the r-process.
↳ hep-phastro-ph.SRnucl-thphysics.space-phBol.A.A.Astron.(2018)·0 citations
23
Identifying a first-order phase transition in neutron star mergers through gravitational waves
Andreas Bauswein🇩🇪 · Niels-Uwe F. Bastian🇵🇱 · David B. Blaschke🇵🇱 · Katerina Chatziioannou🇨🇦 · James A. Clark · Tobias Fischer🇵🇱 · Micaela Oertel🇫🇷
We identify an observable imprint of a first-order hadron-quark phase transition at supranuclear densities on the gravitational-wave (GW) emission of neutron star mergers. Specifically, we show that the dominant postmerger GW frequency f_peak may exhibit a significant deviation from an empirical relation between f_peak and the tidal deformability if a strong first-order phase transition leads to the formation of a gravitationally stable extended quark matter core in the postmerger remnant. A comparison of the GW signatures from a large, representative sample of microphysical, purely hadronic equations of state indicates that this imprint is only observed in those systems which undergo a strong first-order phase transition. Such a shift of the dominant postmerger GW frequency can be revealed by future GW observations, which would provide evidence for the existence of a strong first-order phase transition in the interior of neutron stars.
↳ astro-ph.HEhep-phnucl-thPRL(2019)·471 citations

Affiliations

first authorsco-authorsvia INSPIRE