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Nuclear Theory·nucl-th

Thursday·June 10, 2021

6 papers—1 primary·5 cross-listed

All6Primary1Cross-lists5
  1. 01

    Wigner SU(4) symmetry, clustering, and the spectrum of C

    Shihang Shen🇩🇪 · Timo A. Lähde🇩🇪 · Dean Lee🇺🇸 · Ulf-G. Meißner🇩🇪

    We present lattice calculations of the low-lying spectrum of C using a simple nucleon-nucleon interaction that is independent of spin and isospin and therefore invariant under Wigner's SU(4) symmetry. We find strong signals for all excited states up to ~MeV above the ground state, and explore the structure of each state using a large variety of cluster and harmonic oscillator trial states, projected onto given irreducible representations of the cubic group. We are able to verify earlier findings for the clustering in the Hoyle state and the second state of C. The success of these calculations to describe the full low-lying energy spectrum using spin-independent interactions suggest that either the spin-orbit interactions are somewhat weak in the C system, or the effects of clustering are diminishing their influence. This is in agreement with previous findings from {\it ab initio} shell model calculations.

    nucl-thhep-lathep-phnucl-exEPJA(2021)·23 citations
  2. 02

    Extreme Matter meets Extreme Gravity: Ultra-heavy neutron stars with crossovers and first-order phase transitions

    Hung Tan🇺🇸 · Travis Dore🇺🇸 · Veronica Dexheimer🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸 · Nicolás Yunes🇺🇸

    The speed of sound of the matter within neutron stars may contain non-smooth structure related to first-order phase transitions or or crossovers. Here we investigate what are the observable consequences of structure, such as bumps, spikes, step functions, plateaus, and kinks. One of the main consequences is the possibility of ultra-heavy neutron stars, i.e.~stars with masses significantly heavier than two solar masses. These stars pass all observational and theoretical constraints, including those imposed by recent LIGO/Virgo gravitational-wave observations and NICER X-ray observations. We thoroughly investigate other consequences of this structure in the speed of sound to develop an understanding of how non-smooth features affect astrophysical observables, such as stellar radii, tidal deformability, moment of inertia, and Love number. Our results have important implications to future gravitational wave and X-ray observations of neutron stars and their impact in nuclear astrophysics.

    ↳ astro-ph.HEgr-qcnucl-thPRD(2022)·102 citations
  3. 03

    The soft drop momentum sharing fraction beyond leading-logarithmic accuracy

    Pedro Cal🇳🇱 · Kyle Lee🇺🇸 · Felix Ringer🇺🇸 · Wouter J. Waalewijn🇳🇱

    Grooming techniques, such as soft drop, play a central role in reducing sensitivity of jets to e.g. underlying event and hadronization at current collider experiments. The momentum sharing fraction , of the two branches in a jet that pass the soft drop condition, is one of the most important observables characterizing a collinear splitting inside the jet, and directly probes the QCD splitting functions. In this work, we present a factorization framework that enables a systematic calculation of the corresponding cross section beyond leading-logarithmic (LL) accuracy, showing that this measurement is not only sensitive to the QCD charge but also the spin of the parton that initiates the jet. Our results at next-to-leading logarithmic (NLL) accuracy include non-global logarithms, and provide a first meaningful assessment of the perturbative uncertainty. We present a comparison to the available experimental data from ALICE, ATLAS, and STAR and find excellent agreement.

    ↳ hep-phhep-exnucl-exnucl-thPLB(2022)·29 citations
  4. 04

    Proca equation and vector field quantization in rotating system

    Tian Xu🇨🇳 · Yin Jiang🇨🇳

    A strong background field will change the vacuum structure and the proper basis of a system drastically in both classical and quantum mechanics, e.g. the Landau levels in a background magnetic field. The situation is the same for the rotating case. In such a system the usual set of plane-wave states would no longer be suitable as a starting point of perturbation. Alternatively and straightforwardly in a rapidly and globally rotating system, it is better to reformulate the perturbation computation in principle. In this work we will complete the first step for the spin-1 field, which includes solving the Proca equation in present of a background rotation and complete its canonical quantization. It will be shown that because of the symmetry the eigen states are actually the same as the ones of Maxwell equations in cylindrical coordinate. The propagator as well as the near-central approximation will be obtained by considering the vorticity areas are so small in the relativistic QGP.

    ↳ hep-thhep-phnucl-thCPC(2021)·6 citations
  5. 05

    Light mesons with one dynamical gluon on the light front

    Jiangshan Lan🇨🇳 · Kaiyu Fu🇨🇳 · Chandan Mondal🇨🇳 · Xingbo Zhao🇨🇳 · james P. Vary🇺🇸

    We obtain the light meson mass spectroscopy from the light-front quantum chromodynamics (QCD) Hamiltonian, determined for their constituent quark-antiquark and quark-antiquark-gluon Fock components, together with a three-dimensional confinement. The eigenvectors of the light-front effective Hamiltonian provide a good quality description of the pion electromagnetic form factor, decay constant, and the valence quark distribution functions following QCD scale evolution. We also show that the pion's gluon densities can be probed through the pion-nucleus induced production data. Our pion parton distribution functions provide excellent agreement with production data from widely different experimental conditions.

    ↳ hep-phnucl-thPLB(2022)·77 citations
  6. 06

    Heating in Magnetar Crusts from Electron Captures

    Nicolas Chamel · Anthea Francesca Fantina · Lami Suleiman · Julian-Leszek Zdunik · Pawel Haensel

    The persistent thermal luminosity of magnetars and their outbursts suggest the existence of some internal heat sources located in their outer crust. The compression of matter accompanying the decay of the magnetic field may trigger exothermic electron captures and, possibly, pycnonuclear fusions of light elements that may have been accreted onto the surface from the fallback of supernova debris, from a disk or from the interstellar medium. This scenario bears some resemblance to deep crustal heating in accreting neutron stars, although the matter composition and the thermodynamic conditions are very different. The maximum possible amount of heat that can be released by each reaction and their locations are determined analytically taking into account the Landau--Rabi quantization of electron motion. Numerical results are also presented using experimental, as well as theoretical nuclear data. Whereas the heat deposited is mainly determined by atomic masses, the locations of the sources are found to be very sensitive to the magnetic field strength, thus providing a new way of probing the internal magnetic field of magnetars. Most sources are found to be concentrated at densities g cm with heat power erg/s, as found empirically by comparing cooling simulations with observed thermal luminosity. The change of magnetic field required to trigger the reactions is shown to be consistent with the age of known magnetars. This suggests that electron captures and pycnonuclear fusion reactions may be a viable heating mechanism in magnetars. The present results provide consistent microscopic inputs for neutron star cooling simulations, based on the same model as that underlying the Brussels-Montreal unified equations of state.

    ↳ astro-ph.HEnucl-thUniverse(2021)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE