Nuclear Theory·nucl-th

Tuesday·September 24, 2024

14 papers—6 primary·8 cross-listed

07
Neutron Tagging Can Greatly Reduce Spallation Backgrounds in Super-Kamiokande
Obada Nairat🇺🇸 · John F. Beacom🇺🇸 · Shirley Weishi Li🇺🇸
Super-Kamiokande's spallation backgrounds - the delayed beta decays of nuclides following cosmic-ray muons - are nearly all produced by the small fraction of muons with hadronic showers. We show that these hadronic showers also produce neutrons; their captures can be detected with high efficiency due to the recent addition of dissolved gadolinium to Super-Kamiokande. We show that new cuts based on the neutron tagging of showers could reduce spallation backgrounds by a factor of at least four beyond present cuts. With further work, this could lead to a near-elimination of detector backgrounds above about 6 MeV, which would significantly improve the sensitivity of Super-Kamiokande. These findings heighten the importance of adding gadolinium to Hyper-Kamiokande, which is at a shallower depth. Further, a similar approach could be used in other detectors, for example, the JUNO liquid-scintillator detector, which is also at a shallower depth.
↳ hep-phastro-ph.HEhep-exnucl-ex+1PRD(2025)·13 citations
08
A new approach to handling factorial moment correlations through principal component analysis
Nikolaos Davis🇵🇱
Intermittency analysis of factorial moments is a promising method used for the detection of power-law scaling in high-energy collision data. In particular, it has been employed in the search of fluctuations characteristic of the critical point (CP) of strongly interacting matter. However, intermittency analysis has been hindered by the fact that factorial moments measurements corresponding to different scales are correlated, since the same data are conventionally used to calculate them. This invalidates many assumptions involved in fitting data sets and determining the best fit values of power-law exponents. We present a novel approach to intermittency analysis, employing the well-established statistical and data science tool of Principal Component Analysis (PCA). This technique allows for the proper handling of correlations between scales without the need for subdividing the data sets available.
↳ physics.data-anhep-exhep-phnucl-thPLB(2025)·1 citation
09
Finding Interaction Mechanism between Exotic Molecule and Conventional Hadron
Ri-Qing Qian🇨🇳 · Fu-Lai Wang🇨🇳 · Xiang Liu🇨🇳
An intriguing and important question arises: how do hadronic molecules interact with conventional hadrons? In this work, we propose a novel mechanism to address this issue, focusing on the interactions between hidden-charm molecular pentaquarks ( $P_{c}$ ) and nucleons ( $N$ ). By applying this mechanism, we derive the corresponding interaction potentials, enabling the prediction of the bound state properties. Our results indicate the possible existence of $P_{c} N$ bound states-an entirely new form of matter, ripe for exploration in the era of high-precision hadron spectroscopy. Notably, this mechanism extends beyond the $P_{c} N$ systems and can be applied to any hadronic molecules interacting with conventional hadrons, offering the potential for discovering a variety of novel bound states.
↳ hep-phhep-exhep-latnucl-thPLB(2025)·3 citations
10
Finite-Element Simulations of Rotating Neutron Stars with Anisotropic Crusts and Continuous Gravitational Waves
J. A. Morales · C. J. Horowitz
``Mountains'', or non-axisymmetrical deformations in the elastic crust of rotating neutron stars are efficient radiators of continuous gravitational waves. Recently, small anisotropies were observed in the solid innermost inner core of the Earth. We implement three-dimensional finite-element simulations to study mountains sourced by modest anisotropies in the solid crust of rotating neutron stars. We find that anisotropic mountains may be detectable by current ground-based gravitational-wave detectors and might explain several observed phenomena, confirming the results of a previous work on less realistic neutron star models. In particular, we find that a slightly anisotropic neutron star crust that changes its rotation rate modestly can support an ellipticity of a few $\times$ 10 $^{- 9}$ , which is equivalent to the upper bounds on the ellipticity of some nearby and rapidlly spinning pulsars.
↳ gr-qcnucl-th4 citations
11
Effect of isoscalar and isovector scalar fields on baryon semileptonic decays in nuclear matter
Koichi Saito🇯🇵 · Tsuyoshi Miyatsu🇰🇷 · Myung-Ki Cheoun🇰🇷
The precise determination of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements is very important, because it could be a clue to new physics beyond Standard Theory. This is particular true of $V_{u d}$ , because it is the main contribution to the unitary condition of the CKM matrix elements. The level of accuracy for the test of the unitarity involving the element $V_{u d}$ is now of the order of $1 0^{- 4}$ . Because the precise data for $V_{u d}$ is usually extracted from super-allowed nuclear $β$ decay, it is quite significant to investigate the breaking of SU(3) flavor symmetry on the weak vector coupling constant in nuclear matter. The purpose of this paper is to investigate how the isoscalar scalar ( $σ$ ) and the isovector scalar ( $δ$ or $a_{0}$ ) mean-fields affect the weak vector and axial-vector coupling constants for semileptonic baryon (neutron, $Λ$ or $Ξ^{-}$ ) decay in asymmetric nuclear matter. To do so, we use the quark-meson coupling (QMC) model, where nuclear matter consists of nucleons including quark degrees of freedom bound by the self-consistent exchange of scalar and vector mesons. We pay careful attention to the center of mass correction to the quark currents in matter. We then find that, for neutron $β$ decay in asymmetric nuclear matter, the defect of the vector coupling constant due to the $δ$ field can be of the order of $1 0^{- 4}$ at the nuclear saturation density, which is the same amount as the level of the current uncertainty in the measurements. It is also interesting that, in neutron-rich matter, there exists a certain low density at which isospin symmetry is restored, that is, the $u$ - $d$ quark mass difference vanishes. We conclude that the effect of the isoscalar scalar and the isovector scalar fields should be considered in baryon semileptonic decays in nuclei.
↳ hep-phnucl-exnucl-thPRD(2024)·4 citations
12
A NICER View of PSR J1231 $-$ 1411: A Complex Case
Tuomo Salmi🇳🇱 · Julia S. Deneva🇺🇸 · Paul S. Ray🇺🇸 · Anna L. Watts🇳🇱 · Devarshi Choudhury🇳🇱 · Yves Kini🇳🇱 · Serena Vinciguerra🇳🇱 · H. Thankful Cromartie🇺🇸 · Michael T. Wolff🇺🇸 · Zaven Arzoumanian🇺🇸 · Slavko Bogdanov🇺🇸 · Keith Gendreau🇺🇸 and 7 other authors
Recent constraints on neutron star mass and radius have advanced our understanding of the equation of state (EOS) of cold dense matter. Some of them have been obtained by modeling the pulses of three millisecond X-ray pulsars observed by the Neutron Star Interior Composition Explorer (NICER). Here, we present a Bayesian parameter inference for a fourth pulsar, PSR J1231 $-$ 1411, using the same technique with NICER and XMM-Newton data. When applying a broad mass-inclination prior from radio timing measurements and the emission region geometry model that can best explain the data, we find likely converged results only when using a limited radius prior. If limiting the radius to be consistent with the previous observational constraints and EOS analyses, we infer the radius to be $12.6 \pm 0.3$ km and the mass to be $1.0 4_{- 0.03}^{+ 0.05}$ $M_{⊙}$ , each reported as the posterior credible interval bounded by the $16 %$ and $84 %$ quantiles. If using an uninformative prior but limited between $10$ and $14$ km, we find otherwise similar results, but $R_{eq} = 13. 5_{- 0.5}^{+ 0.3}$ km for the radius. In both cases, we find a nonantipodal hot region geometry where one emitting spot is at the equator or slightly above, surrounded by a large colder region, and where a noncircular hot region lies close to southern rotational pole. If using a wider radius prior, we only find solutions that fit the data significantly worse. We discuss the challenges in finding the better fitting solutions, possibly related to the weak interpulse feature in the pulse profile.
↳ astro-ph.HEnucl-thApJ(2024)·121 citations
13
Discovery of a new long-lived isomer in $^{114}$ Rh via Penning-trap mass spectrometry
M. Stryjczyk🇫🇮 · A. Jaries🇫🇮 · W. Ryssens🇧🇪 · M. Bender🇫🇷 · A. Kankainen🇫🇮 · T. Eronen🇫🇮 · Z. Ge🇫🇮 · I.D. Moore🇫🇮 · M. Mougeot🇫🇮 · A. Raggio🇫🇮 · J. Ruotsalainen🇫🇮
We report on mass measurements of three long-lived states in $^{114}$ Rh performed with the JYFLTRAP Penning-trap mass spectrometer: the ground state and two isomers with estimated half-lives of about one second. The used Phase-Imaging Ion-Cyclotron-Resonance technique allowed for the discovery of a so far unknown second long-lived isomer. All three states were produced directly in proton-induced fission on a uranium target, whereas only the isomeric states were populated in the $β$ decay of the $^{114}$ Ru ground state with spin-parity $0^{+}$ . We propose spin-parity assignments of $(6^{-})$ for the ground state, and $(3^{+})$ and $(0^{-})$ for the isomers. They resolve the puzzle of anomalous fission yields of this isotope despite the existing literature assigning a low angular momentum to the ground state. The experimental evidence is further supported by a detailed analysis based on mean-field calculations with the BSkG3 model. As for many other nuclei in this mass region, considering triaxial shapes is decisive for the interpretation of low-lying states of this nucleus. The discovery of a new isomer in $^{114}$ Rh and our theoretical work challenge the currently adopted spin-parity assignments in this and several other odd-odd neutron-rich Rh isotopes.
↳ nucl-exnucl-thPLB(2025)·5 citations
14
Simulating Charm Quarks in IP-Glasma Initial Stage and Quark-Gluon Plasma: A Hybrid Approach for charm quark phenomenology
Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Manu Kurian🇺🇸 · Björn Schenke🇺🇸 · Mayank Singh🇺🇸
We present phenomenological findings on charm quark transport while including its energy loss in both pre-equilibrium and hydrodynamic stages of the evolution. We employed the MARTINI event generator for the production and evolution of heavy quarks in the relativistic heavy-ion collisions. The sensitivity of the heavy meson nuclear modification factor and flow coefficient to the early stage of heavy-ion collisions and bulk medium evolution is analyzed for Pb+Pb collisions at 5.02 TeV. Our study provides insights into the interaction strength of charm quarks during the early phase and within the quark-gluon plasma.
↳ hep-phnucl-thEPJ Web Conf.(2025)·0 citations

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