Nuclear Theory·nucl-th

Wednesday·March 8, 2023

11 papers—4 primary·7 cross-listed

01
Empirical neutron star mass formula based on experimental observables
Hajime Sotani · Tomoya Naito
We derive the empirical formulae expressing the mass and gravitational redshift of a neutron star, whose central density is less than threefold the nuclear saturation density, as a function of the neutron-skin thickness or the dipole polarizability of $^{208} Pb$ or $^{132} Sn$ , especially focusing on the 8 Skyrme-type effective interactions. The neutron star mass and its gravitational redshift can be estimated within $\approx 10 %$ errors with our formulae, while the neutron star radius is also expected within a few $%$ errors by combining the derived formulae. Owing to the resultant empirical formulae, we find that the neutron star mass and radius are more sensitive to the neutron-skin thickness of $^{208} Pb$ than the dipole polarizability of $^{208} Pb$ or $^{132} Sn$ .
nucl-thastro-ph.HEPRC(2023)·14 citations
02
Search for jet quenching effects on the plain jet mass in Pb+Pb collisions at the LHC with a multiphase transport model
Xiang-Pan Duan🇨🇳 · Guo-Liang Ma🇨🇳
The plain jet mass distributions of reconstructed jets are investigated in p+p and 0-10 $%$ most central Pb+Pb collisions at $s_{NN} = 2.76 TeV$ using a dynamical multiphase transport model with a string melting mechanism. It is observed that the mean charged jet mass increases with increasing jet transverse momentum and jet radius in central Pb+Pb collisions. It is demonstrated that the plain jet mass of reconstructed partonic jet is shifted to a higher value after the evolution of partonic stage due to jet quenching in central Pb+Pb collisions. However, the jet mass shift effect is strongly weakened by non-perturbative effects from hadronization and hadron rescatterings. This makes it difficult to observe significant hot medium modification effects on the plain jet mass distribution in the final state of relativistic heavy-ion collisions.
nucl-thhep-phnucl-exEPJA(2023)·3 citations
03
Improved Superscaling in Quasielastic Electron Scattering with Relativistic Effective Mass
P.R. Casale🇪🇸 · J.E. Amaro🇪🇸 · V.L. Martinez-Consentino🇪🇸 · I. Ruiz Simo🇪🇸
Superscaling in electron scattering from nuclei is re-examined paying special attention to the definition of the averaged single-nucleon responses. The validity of the extrapolation of nucleon responses in the Fermi gas has been examined, which previously lacked a theoretical foundation. To address this issue, we introduce new averaged responses with a momentum distribution smeared around the Fermi surface, allowing for momenta above the Fermi momentum. This approach solves the problem of negativity in the extrapolation away from the scaling region and, at the same time, validates its use in the scaling analysis. This work has important implications for the interpretation of scaling data and contributes to the development of a more complete understanding of the scaling approach.
nucl-thhep-phUniverse(2023)·8 citations
04
Solving Schrodinger equations using physically constrained neural network
Kai-Fang Pu · Hanlin Li · Hong-Liang Lu · Long-Gang Pang
Deep neural network (DNN) and auto differentiation have been widely used in computational physics to solve variational problems. When DNN is used to represent the wave function to solve quantum many-body problems using variational optimization, various physical constraints have to be injected into the neural network by construction, to increase the data and learning efficiency. We build the unitary constraint to the variational wave function using a monotonic neural network to represent the Cumulative Distribution Function (CDF) $F (x) = \int_{- \infty}^{x} ψ^{*} ψ d x^{'}$ . Using this constrained neural network to represent the variational wave function, we solve Schrodinger equations using auto-differentiation and stochastic gradient descent (SGD), by minimizing the violation of the trial wave function $ψ (x)$ to the Schrodinger equation. For several classical problems in quantum mechanics, we obtain their ground state wave function and energy with very low errors. The method developed in the present paper may pave a new way in solving nuclear many body problems in the future.
nucl-thCPC(2023)·10 citations
05
A Coherent View of the Quark-Gluon Plasma from Energy Correlators
Carlota Andres🇫🇷 · Fabio Dominguez🇪🇸 · Jack Holguin🇫🇷 · Cyrille Marquet🇫🇷 · Ian Moult🇺🇸
The ability to measure detailed aspects of the substructure of high-energy jets traversing the quark-gluon plasma (QGP) has provided a new window into its internal dynamics. However, drawing robust conclusions from traditional jet substructure observables has been difficult. In this manuscript we expand on a new approach to jet substructure in heavy-ion collisions based on the study of correlation functions of energy flow operators (energy correlators). We compute the two-point energy correlator of an in-medium massless quark jet and perform a detailed numerical analysis of the produced spectra. Our calculation incorporates vacuum radiation resummed at next-to-leading log accuracy together with the leading order contribution in medium-induced splittings evaluated through the BDMPS-Z multiple scattering and GLV single scattering formalisms for a static brick of QGP. Our analysis demonstrates how particular features of the modifications of in-medium splittings are imprinted in the correlator spectra, particularly showing how energy correlators may be used to extract the onset of colour coherence. We further present a comprehensive discussion on the accuracy and limitations of our study emphasizing how it can be systematically improved. This work sets the foundations for a rich program studying energy correlators in heavy-ion collisions.
↳ hep-phhep-exhep-thnucl-ex+1JHEP(2023)·98 citations
06
Molecular states in $D_{s}^{(*) +} Ξ_{c}^{(^{'}, *)}$ systems
Nijiati Yalikun🇨🇳 · Xiang-Kun Dong🇨🇳 · Bing-Song Zou🇨🇳
The possible hadronic molecules in $D_{s}^{(*) +} Ξ_{c}^{(^{'}, *)}$ systems with $J^{P} = 1/ 2^{-}, 3/ 2^{-}$ and $5/ 2^{-}$ are investigated with interactions described by light meson exchanges. By varying the cutoff in a phenomenologically reasonable range of $1 \sim 2.5$ GeV, we find ten near-threshold (bound or virtual) states in the single-channel case. After introducing the coupled-channel dynamics of $D_{s}^{+} Ξ_{c}$ - $D_{s}^{+} Ξ_{c}^{^{'}}$ - $D_{s}^{*+} Ξ_{c}$ - $D_{s}^{+} Ξ_{c}^{*}$ - $D_{s}^{*+} Ξ_{c}^{^{'}}$ - $D_{s}^{*+} Ξ_{c}^{*}$ systems, these states, except those below the lowest channels in each $J^{P}$ sector, move into the complex energy plane and become resonances in the mass range of $4.43 \sim 4.76$ GeV. Their spin-parities and nearby thresholds are $1/ 2^{-} (D_{s}^{+} Ξ_{c})$ , $1/ 2^{-} (D_{s}^{+} Ξ_{c}^{^{'}})$ , $1/ 2^{-} (D_{s}^{*+} Ξ_{c})$ , $1/ 2^{-} (D_{s}^{*+} Ξ_{c}^{^{'}})$ , $1/ 2^{-} (D_{s}^{*+} Ξ_{c}^{*})$ , $3/ 2^{-} (D_{s}^{*+} Ξ_{c})$ , $3/ 2^{-} (D_{s}^{+} Ξ_{c})$ , $3/ 2^{-} (D_{s}^{*+} Ξ_{c}^{^{'}})$ , $3/ 2^{-} (D_{s}^{*+} Ξ_{c}^{*})$ , and $5/ 2^{-} (D_{s}^{*+} Ξ_{c}^{*})$ . The impacts of the $δ (r)$ -term in the one-boson-exchange model on these states are presented. Setting $Λ = 1.5$ GeV as an illustrative value, it is found that $1/ 2^{-} (D_{s}^{+} Ξ_{c})$ is a stable bound state (becoming unstable if turning on the coupling to lower channels), $1/ 2^{-} (D_{s}^{*+} Ξ_{c})$ and $3/ 2^{-} (D_{s}^{*+} Ξ_{c})$ are physical resonances in both cases of including or excluding the $δ (r)$ -term, while the other seven states are physical resonances or ``virtual-state-like" poles near thresholds, depending on including the $δ (r)$ -term or not. In addition, the partial decay widths of the physical resonances are provided. These double-charm hidden-strangeness pentaquark states, as the partners of experimentally observed $P_{c}$ and $P_{cs}$ states, can be searched for in the $D^{(*)} Λ_{c}$ final states in future.
↳ hep-phnucl-thCPC(2023)·12 citations
07
The study on the structure of exotic states $χ_{c 1} (3872)$ via beauty-hadron decays in $pp$ collisions at $s = 8 TeV$
Chun-tai Wu🇨🇳 · Zhi-Lei She🇨🇳 · Xin-Ye Peng🇨🇳 · Xiao-Lin Kang🇨🇳 · Hong-Ge Xu Dai-Mei Zhou🇨🇳 · Gang Chen🇨🇳 · Ben-Hao Sa🇨🇳
A dynamically constrained phase-space coalescence (DCPC) model was introduced to study the exotic state $χ_{c 1} (3872)$ yield for three possible structures: tetraquark state, nuclear-like state, and molecular state respectively, where the hadronic final states generated by the parton and hadron cascade model (PACIAE). The $χ_{c 1} (3872)$ / $ψ (2 S)$ cross-section ratio from beauty-hadron decays (non-prompt) based on the $χ_{c 1} (3872)$ or $ψ (2 S) \to J / ψ π^{+} π^{-}$ bound state in the decay chains as a function of charged-particle multiplicity and transverse momentum in $pp$ collisions at $s = 8 TeV$ are calculated. A tetraquark state scenario from PACIAE+DCPC model shows better agreement with the LHCb and ATLAS measurements for the non-prompt $χ_{c 1} (3872)$ / $ψ (2 S)$ cross-section ratio distributions, indicating that the $χ_{c 1} (3872)$ is more likely to be a compact tetraquark state.
↳ hep-phnucl-thPRD(2023)·11 citations
08
Tuning of Efimov states in non-integer dimensions
E. Garrido · A.S. Jensen
The purpose of this paper is to show that, by combining Feshbach resonances with external confining potentials, the energy scale factor of neighboring Efimov states can be tremendously reduced. The Efimov conditions can be reached for systems made of three different particles. For the case of two identical light particles and a heavy particle the energy factor can be reduced by many orders of magnitude, and the Efimov states are in this way more easily reachable experimentally. The equivalence between external potentials and the formulation in terms of non-integer dimensions, $d$ , is exploited. The technically simpler $d$ -method is used to derive analytic expressions for two-component relative wave functions describing two short-range square-well interacting particles. The two components express one open and one closed channel. The scattering length is obtained after phase shift expansion, providing an analytic form for the Efimov condition. We illustrate the results by means of systems made of $^{7}$ Li, $^{39}$ K, and $^{87}$ Rb, with realistic parameters. The related pairs of dimension and magnetic field are shown and discussed. The results are universal as they only rely on large-distance properties.
↳ physics.atom-phnucl-thquant-phEur.Phys.J.D(2023)·2 citations
09
Jet polarisation in an anisotropic medium
Sigtryggur Hauksson🇫🇷 · Edmond Iancu🇫🇷
We study the evolution of an energetic jet which propagates in an anisotropic quark-gluon plasma, as created in the intermediate stages of ultrarelativistic heavy-ion collisions. We argue that the partons of the jet should acquire a non-zero average polarisation proportional to the medium anisotropy. We first observe that the medium anisotropy introduces a difference between the rates for transverse momentum broadening along the two directions perpendicular to the jet axis. In turn, this difference leads to a polarisation-dependent bias in the BDMPS-Z rates for medium-induced gluon branching. Accordingly, the daughter gluons in a branching process can carry net polarisation even if their parent gluon was unpolarised. Using these splitting rates, we construct kinetic equations which describe the production and transmission of polarisation via multiple branching in an anisotropic medium. The solutions to these equations show that polarisation is efficiently produced via quasi-democratic branchings, but then it is rapidly washed out by the subsequent branchings, due to the inability of soft gluons to keep trace of the polarisation of their parents. Based on that, we conclude that a net polarisation for the jet should survive in the final state if and only if the medium anisotropy is sizeable as the jet escapes the medium.
↳ hep-phnucl-thJHEP(2023)·39 citations
10
Towards a universal description of hadronic phase of QCD
Aman Abhishek🇮🇳 · Sayantan Sharma🇮🇳
Mean-field model quantum field theories of hadrons were traditionally developed to describe cold and dense nuclear matter and are by now very well constrained from the recent neutron star merger observations. We show that when augmented with additional known hadrons and resonances but not included earlier, these mean-field models can be extended beyond its regime of applicability. Calculating some specific ratios of baryon number susceptibilities for finite temperature and moderate values of baryon densities within mean-field approximation, we show that these match consistently with the lattice QCD data available at lower densities, unlike the results obtained from a non-interacting hadron resonance gas model. We also estimate the curvature of the line of constant energy density, fixed at its corresponding value at the chiral crossover transition in QCD, in the temperature-density plane. The number density at low temperatures and high density is found to be about twice the nuclear saturation density along the line of constant energy density of $ϵ = 348 \pm 41$ MeV/ $fm^{3}$ . Moreover from this line we can indirectly constrain the critical end-point of QCD to be beyond $μ_{B} = 596$ MeV for temperature $\sim 125$ MeV.
↳ hep-phhep-latnucl-thPRD(2024)·2 citations
11
The Neutron Mean Life and Big Bang Nucleosynthesis
Tsung-Han Yeh🇨🇦 · Keith A. Olive🇺🇸 · Brian D. Fields🇺🇸
We explore the effect of neutron lifetime and its uncertainty on standard big-bang nucleosynthesis (BBN). BBN describes the cosmic production of the light nuclides $^{1} H$ , $D$ , $^{3} H$ + $^{3} He$ , $^{4} He$ , and $^{7} Li$ + $^{7} Be$ in the first minutes of cosmic time. The neutron mean life $τ_{n}$ has two roles in modern BBN calculations: (1) it normalizes the matrix element for weak $n \leftrightarrow p$ interconversions, and (2) it sets the rate of free neutron decay after the weak interactions freeze out. We review the history of the interplay between $τ_{n}$ measurements and BBN, and present a study of the sensitivity of the light element abundances to the modern neutron lifetime measurements. We find that $τ_{n}$ uncertainties dominate the predicted $^{4} He$ error budget, but these theory errors remain smaller than the uncertainties in $^{4} He$ observations, even with the dispersion in recent neutron lifetime measurements. For the other light-element predictions, $τ_{n}$ contributes negligibly to their error budget. Turning the problem around, we combine present BBN and cosmic microwave background (CMB) determinations of the cosmic baryon density to $predict$ a "cosmologically preferred" mean life of $τ_{n} (BBN + CMB) = 870 \pm 16 sec$ , which is consistent with experimental mean life determinations. We go on to show that if future astronomical and cosmological helium observations can reach an uncertainty of $σ_{obs} (Y_{p}) = 0.001$ in the $^{4} He$ mass fraction $Y_{p}$ , this could begin to discriminate between the mean life determinations.
↳ astro-ph.COhep-phnucl-exnucl-thUniverse(2023)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE