Nuclear Theory·nucl-th

Tuesday·May 24, 2022

11 papers—5 primary·6 cross-listed

06
Distinguishing (Dirac or Majorana) neutrinos in purely leptonic decays of leptons
Yao Yu🇨🇳 · Bai-Cian Ke🇨🇳
We investigate purely leptonic decays of leptons $\l^{' -} \to l^{-} ν ˉ_{l} ν_{l^{'}}$ to distinguish Dirac or Majorana neutrinos. We derive the differences of the decay width (and associated quantities) between the two neutrino hypotheses by the effect of identical particles. Evidence from experimental data makes the hypothesis of Majorana neutrinos very unlikely and our results strongly favor the hypothesis of Dirac neutrinos (in the standard three-neutrino theory). Moreover, our exploration for decay widths can be extended to the polarization angles of leptons, which will inspire new information for experimental and theoretical studies.
↳ hep-phhep-exhep-thnucl-th0 citations
07
Attractive $N$ - $ϕ$ Interaction and Two-Pion Tail from Lattice QCD near Physical Point
Yan Lyu🇨🇳 · Takumi Doi🇯🇵 · Tetsuo Hatsuda🇯🇵 · Yoichi Ikeda🇯🇵 · Jie Meng🇨🇳 · Kenji Sasaki🇯🇵 · Takuya Sugiura🇯🇵
First results on the interaction between the $ϕ$ -meson and the nucleon ( $N$ ) are presented based on the ( $2 + 1$ )-flavor lattice QCD simulations with nearly physical quark masses. Using the HAL QCD method, the spacetime correlation of the $N$ - $ϕ$ system in the spin 3/2 channel is converted into the $N$ - $ϕ$ scattering phase shift through the interaction potential. The $N$ - $ϕ$ potential appears to be a combination of a short-range attractive core and a long-range attractive tail. The latter is found to be consistent with the two-pion exchange (TPE) obtained from the interaction between a color-dipole and the nucleon. The resultant scattering length and effective range for $m_{π} =$ 146.4 MeV are $a_{0}^{(3/2)} = - 1.43 (23)_{stat.} (_{- 06}^{+ 36})_{syst.} fm$ and $r_{eff}^{(3/2)} = 2.36 (10)_{stat.} (_{- 48}^{+ 02})_{syst.} fm$ , respectively. The magnitude of the scattering length is shown to have nontrivial dependence of $m_{π}$ and is sensitive to the existence of the long-range tail from TPE.
↳ hep-lathep-exhep-phnucl-ex+1PRD(2022)·73 citations
08
Astrophysical implications on hyperon couplings and hyperon star properties with relativistic equations of states
Xiangdong Sun🇨🇳 · Zhiqiang Miao🇨🇳 · Baoyuan Sun🇨🇳 · Ang Li🇨🇳
Hyperons are essential constituents in the neutron star interior. The poorly-known hyperonic interaction is a source of uncertainty for studying laboratory hypernuclei and neutron star observations. In this work, we perform Bayesian inference of phenomenological hyperon-nucleon interactions using the tidal-deformability measurement of the GW170817 binary neutron star merger as detected by LIGO/Virgo and the mass-radius measurements of PSR J0030+0541 and PSR J0740+6620 as detected by NICER. The analysis is based on a set of stiff relativistic neutron-star-matter equation of states with hyperons from the relativistic mean-field theory, naturally fulfilling the causality requirement and empirical nuclear matter properties. We specifically utilize the strong correlation recently deduced between the scalar and vector meson hyperon couplings, imposed by the measured $Λ$ separation energy in single- $Λ$ hypernuclei, and perform four different tests with or without the strong correlation. We find that the laboratory hypernuclear constraint ensures a large enough $Λ$ -scalar-meson coupling to match the large vector coupling in hyperon star matter. When adopting the current most probable intervals of hyperon couplings from the joint analysis of laboratory and astrophysical data, we find the maximum mass of hyperon stars is at most $2.17 6_{- 0.202}^{+ 0.085} M_{⊙}$ ( $68%$ credible interval) from the chosen set of stiff equation of states. The reduction of the stellar radius due to hyperons is quantified based on our analysis and various hyperon star properties are provided.
↳ astro-ph.HEastro-ph.SRnucl-thApJ(2023)·52 citations
09
Strangeness enhancement across collision systems without a plasma
Christian Bierlich🇸🇪 · Smita Chakraborty🇸🇪 · Gösta Gustafson🇸🇪 · Leif Lönnblad🇸🇪
We present novel rope hadronization results for strange hadron enhancement in pp, pPb, and PbPb collisions using PYTHIA/Angantyr at LHC energies. With the rope model for string fragmentation, we find that the strangeness and baryon enhancement has a coherent increase across all collision systems as a function of average charged central multiplicity, in qualitative agreement with LHC data. In AA collisions, we find that the baryonic yields overshoot data at high multiplicities, and we discuss how a combination of rope hadronization with other string interactions may tame this rise.
↳ hep-phnucl-thPLB(2022)·25 citations
10
Resonance form factors from finite-volume correlation functions with the external field method
Jonathan Lozano🇩🇪 · Ulf-G. Meißner🇩🇪 · Fernando Romero-López🇺🇸 · Akaki Rusetsky🇩🇪 · Gerrit Schierholz🇩🇪
A novel method for the extraction of form factors of unstable particles on the lattice is proposed. The approach is based on the study of two-particle scattering in a static, spatially periodic external field by using a generalization of the Lüscher method in the presence of such a field. It is shown that the resonance form factor is given by the derivative of the resonance pole position in the complex plane with respect to the coupling constant to the external field. Unlike the standard approach, this proposal does not suffer from problems caused by the presence of the triangle diagram.
↳ hep-lathep-phnucl-thJHEP(2022)·11 citations
11
Pion damping width and pion spectral function in hot pion gas
D. Goderidze🇷🇺 · A. Friesen🇷🇺 · Yu. Kalinovsky🇷🇺
The temperature behaviour of the pion width in the hadronic phase is investigated in the framework of the NJL model. The contribution to the width from the pion-pion collision is considered with a scalar sigma-meson as an intermediate state. It is shown that the pion width significantly broadens at $T > 0.1$ GeV. Using the two-step iteration method, suggested by Kadanoff and Baym, the pion spectral function in a hot pion gas is calculated at different temperatures.
↳ hep-phnucl-thInt.J.Mod.Phys.A(2022)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE

Distinguishing (Dirac or Majorana) neutrinos in purely leptonic decays of leptons

Attractive N-ϕ Interaction and Two-Pion Tail from Lattice QCD near Physical Point

Astrophysical implications on hyperon couplings and hyperon star properties with relativistic equations of states

Strangeness enhancement across collision systems without a plasma

Resonance form factors from finite-volume correlation functions with the external field method

Pion damping width and pion spectral function in hot pion gas

Affiliations

Attractive $N$ - $ϕ$ Interaction and Two-Pion Tail from Lattice QCD near Physical Point