Nuclear Theory·nucl-th

Monday·July 22, 2019

8 papers—2 primary·6 cross-listed

03
[Submitted on 18 Jul 2019] (cross-list from nucl-ex)
Pion and Kaon Structure at the Electron-Ion Collider
Arlene C. Aguilar🇧🇷 · Zafir Ahmed🇨🇦 · Christine Aidala🇺🇸 · Salina Ali🇺🇸 · Vincent Andrieux🇺🇸 · John Arrington🇺🇸 · Adnan Bashir🇲🇽 · Vladimir Berdnikov🇺🇸 · Daniele Binosi🇮🇹 · Lei Chang🇨🇳 · Chen Chen🇩🇪 · Muyang Chen🇨🇳 and 39 other authors
Understanding the origin and dynamics of hadron structure and in turn that of atomic nuclei is a central goal of nuclear physics. This challenge entails the questions of how does the roughly 1 GeV mass-scale that characterizes atomic nuclei appear; why does it have the observed value; and, enigmatically, why are the composite Nambu-Goldstone (NG) bosons in quantum chromodynamics (QCD) abnormally light in comparison? In this perspective, we provide an analysis of the mass budget of the pion and proton in QCD; discuss the special role of the kaon, which lies near the boundary between dominance of strong and Higgs mass-generation mechanisms; and explain the need for a coherent effort in QCD phenomenology and continuum calculations, in exa-scale computing as provided by lattice QCD, and in experiments to make progress in understanding the origins of hadron masses and the distribution of that mass within them. We compare the unique capabilities foreseen at the electron-ion collider (EIC) with those at the hadron-electron ring accelerator (HERA), the only previous electron-proton collider; and describe five key experimental measurements, enabled by the EIC and aimed at delivering fundamental insights that will generate concrete answers to the questions of how mass and structure arise in the pion and kaon, the Standard Model's NG modes, whose surprisingly low mass is critical to the evolution of our Universe.
Comments:
16 pages, 12 figures, to appear in the European Physical Journal A - "Hadrons and Nuclei"
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1907.08218 [pdf]
EPJA(2019)·210 citations
04
[Submitted on 19 Jul 2019] (cross-list from hep-ph)
Exclusive production of a large mass photon pair
A. Pedrak🇵🇱 · B. Pire🇫🇷 · L. Szymanowski🇵🇱 · J. Wagner🇵🇱
The scattering amplitude for photoproduction of a large invariant mass diphoton in the generalized Bjorken regime has a very peculiar and interesting analytical structure. The leading twist leading order amplitude is proportional to valence quark generalized parton distributions taken at the border value $x = \pm ξ$ . Cross section estimates show that this process is measurable at JLab energies. The angular asymmetry triggered by a linearly polarized photon beam is large.
Comments:
5 pages, contribution to the proceedings of the XXVII. International Workshop on Deep-Inelastic Scattering and Related Subjects, April 8-12, 2019,Torino, Italy
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1907.08431 [pdf]
PoS(2019)·0 citations
05
[Submitted on 19 Jul 2019] (cross-list from astro-ph.HE)
Gravitational waves from neutron star mergers and their relation to the nuclear equation of state
Luca Baiotti🇯🇵
In this article, I introduce ideas and techniques to extract information about the equation of state of matter at very high densities from gravitational waves emitted before, during and after the merger of binary neutron stars. I also review current work and results on the actual use of the first gravitational-wave observation of a neutron-star merger to set constraints on properties of such equation of state. In passing, I also touch on the possibility that what we observe in gravitational waves are not neutron stars, but something more exotic. In order to make this article more accessible, I also review the dynamics and gravitational-wave emission of neutron-star mergers in general, with focus on numerical simulations and on which representations of the equation of state are used for studies on binary systems.
Comments:
48 pages of text; invited review article; matches the final published version available (with better layout) at https://authors.elsevier.com/a/1ZoHUXLw5tMgD
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1907.08534 [pdf]
PPNP(2019)·275 citations
06
[Submitted on 19 Jul 2019] (cross-list from hep-ph)
Parton distributions from nonlocal chiral SU(3) effective theory: Flavor asymmetries
Y. Salamu🇨🇳 · Chueng-Ryong Ji🇺🇸 · W. Melnitchouk🇺🇸 · A. W. Thomas🇦🇺 · P. Wang🇨🇳 · X. G. Wang🇦🇺
Using recently derived results for one-loop hadronic splitting functions from a nonlocal implementation of chiral effective theory, we study the contributions from pseudoscalar meson loops to flavor asymmetries in the proton. Constraining the parameters of the regulating functions by inclusive production of $n$ , $Δ^{++}$ , $Λ$ and $Σ^{*+}$ baryons in $pp$ collisions, we compute the shape of the light antiquark asymmetry $d ˉ - u ˉ$ in the proton and the strange asymmetry $s - s ˉ$ in the nucleon sea. With these constraints, the magnitude of the $d ˉ - u ˉ$ asymmetry is found to be compatible with that extracted from the Fermilab E866 Drell-Yan measurement, with no indication of a sign change at large values of $x$ , and an integrated value in the range $⟨ d ˉ - u ˉ ⟩ \approx 0.09 - 0.17$ . The $s - s ˉ$ asymmetry is predicted to be positive at $x > 0$ , with compensating negative contributions at $x = 0$ , and an integrated $x$ -weighted moment in the range $⟨ x (s - s ˉ)⟩ \approx (0.9 - 2.5) \times 1 0^{- 3}$ .
Comments:
43 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1907.08551 [pdf]
PRD(2019)·27 citations
07
[Submitted on 19 Jul 2019] (cross-list from astro-ph.HE)
Interplay between $Δ$ Particles and Hyperons in Neutron Stars
Patricia Ribes🇪🇸 · Angels Ramos🇪🇸 · Laura Tolos🇩🇪 · Claudia Gonzalez-Boquera🇪🇸 · Mario Centelles🇪🇸
We analyze the effects of including $Δ (1232)$ isobars in an equation of state (EoS) for cold, $β$ -stable neutron star matter, employing relativistic nuclear mean field theory. The selected EoS reproduces the properties of nuclear matter and finite nuclei and, in the astrophysical context, allows for the presence of hyperons in neutron stars having masses larger than 2 $M_{⊙}$ . We find that the composition and structure of neutron stars is critically influenced by the addition of the $Δ$ isobars, which allows us to constrain their interaction with the meson fields taking into account astrophysical information. Imposing that the EoS is stable and ensures the existence of 2 $M_{⊙}$ neutron stars, as well as requiring agreement with data of $Δ$ excitation in nuclei, we find that, in the absence of other mechanisms stiffening the EoS at high densities, the interaction of the $Δ$ isobars with the sigma and omega meson fields must be at least 10\% stronger than that of the nucleons. Moreover, the neutron star moment of inertia turns out to be sensitive to the presence of $Δ$ isobars, whereas the inclusion of $Δ$ isobars in the EoS allows for smaller stellar radii and for a lower value of the tidal deformability consistent with the analysis of the GW170817 merger event.
Comments:
13 pages, 9 figures, 1 table
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
1907.08583 [pdf]
ApJ(2019)·73 citations
08
[Submitted on 19 Jul 2019] (cross-list from hep-th)
Effective Lagrangian for Nambu-Goldstone modes in nonequilibrium open systems
Masaru Hongo🇯🇵 · Suro Kim🇯🇵 · Toshifumi Noumi🇯🇵 · Atsuhisa Ota🇬🇧
We develop the effective field theory of diffusive Nambu-Goldstone (NG) modes associated with spontaneous internal symmetry breaking taking place in nonequilibrium open systems. The effective Lagrangian describing semi-classical dynamics of the NG modes is derived and matching conditions for low-energy coefficients are also investigated. Due to new terms peculiar to open systems, the associated NG modes show diffusive gapless behaviors in contrast to the propagating NG mode in closed systems. We demonstrate two typical situations relevant to the condensed matter physics and high-energy physics, where diffusive type-A or type-B NG modes appear.
Comments:
6 pages(+3 pages supplemental material), 1 figure
Subjects:
High Energy Physics — Theory (hep-th); Quantum Gases (cond-mat.quant-gas); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1907.08609 [pdf]
PRD(2021)·38 citations

Affiliations

first authorsco-authorsvia INSPIRE

Pion and Kaon Structure at the Electron-Ion Collider

Exclusive production of a large mass photon pair

Gravitational waves from neutron star mergers and their relation to the nuclear equation of state

Parton distributions from nonlocal chiral SU(3) effective theory: Flavor asymmetries

Interplay between Δ Particles and Hyperons in Neutron Stars

Effective Lagrangian for Nambu-Goldstone modes in nonequilibrium open systems

Affiliations

Interplay between $Δ$ Particles and Hyperons in Neutron Stars