Nuclear Theory·nucl-th

Tuesday·April 18, 2023

11 papers—8 primary·3 cross-listed

01
Quantum fluctuations induce collective multiphonons in finite Fermi liquids
Petar Marević🇫🇷 · David Regnier🇫🇷 · Denis Lacroix🇫🇷
We show that collective multiphonon states in atomic nuclei emerge at high excitation energies when quantum fluctuations in the collective space are included beyond the independent-particle approximation. The quadrupole response of a nucleus is studied using an extension of the nuclear time-dependent density-functional theory that mixes several many-body trajectories. While a single trajectory can account for the excitation of the first collective quantum, the second and the third quanta emerge due to the interference between trajectories. The collective spectrum, found as nearly harmonic, is in excellent agreement with the experimentally observed three quanta of the isoscalar giant quadrupole resonance in $^{40}$ Ca. This study offers guidance for multiphonon searches in other self-bound systems and demonstrates the resistance to internal excitation of finite Fermi liquids.
nucl-thquant-phPRC(2023)·18 citations
02
Properties of First-Order Hadron-Quark Phase Transition from Inverting Neutron Star Observables
Nai-Bo Zhang🇨🇳 · Bao-An Li🇺🇸
By inverting the observational data of several neutron star observables in the three dimensional parameter space of the constant speed of sound (CSS) model while fixing all hadronic Equation of State parameters at their currently known most probable values, we constrain the three parameters of the CSS model and their correlations. Using two lower radius limits of $R_{2.01} = 11.41$ km and $R_{2.01} = 12.2$ km for PSR J0740+6620 obtained from two independent analyses using different approaches by the Neutron Star Interior Composition Explorer (NICER) Collaboration, the speed of sound squared $c_{QM}^{2}$ in quark matter is found to have a lower limit of $0.35$ and $0.43$ in unit of $c^{2}$ , respectively, above its conformal limit of $c_{QM}^{2} < 1/3$ . An approximately linear correlation between the first-order hadron-quark transition density $ρ_{t}$ and its strength $Δ ε$ is found. Moreover, the presence of twin star is deemed improbable by the present work.
nucl-thastro-ph.HEnucl-exPRC(2023)·18 citations
03
Structure of neutron-rich He $Λ$ hypernuclei using the cluster orbital shell model
Takayuki Myo🇯🇵 · Emiko Hiyama🇯🇵
We calculated the energy spectra of the neutron-rich He $Λ$ hypernuclei with $A = 6$ to 9 within the framework of an $α + Λ + X n$ ( $X = 1$ --4) cluster model using the cluster orbital shell model. The employed constituent particles reproduce their observed properties. For resonant states of core nuclei such as $^{5}$ He, $^{6}$ He, and $^{7}$ He, the complex scaling method is employed to obtain energies and decay widths. The calculated ground states of $_{Λ}^{6}$ He and $_{Λ}^{7}$ He are in good agreement with published data. The energy levels of $_{Λ}^{8}$ He and $_{Λ}^{9}$ He are predicted. In $_{Λ}^{9}$ He, we find one deeply bound state and two excited resonant states, which are proposed to be produced at the Japan proton accelerator research complex (J-PARC) by the double-charge-exchange reaction $(π^{-}, K^{+})$ using a $^{9}$ Be target.
nucl-thnucl-exPRC(2023)·11 citations
04
Double-strangeness exchange reactions in a hybrid Regge-plus-resonance approach
Sang-Ho Kim🇰🇷 · Jung Keun Ahn🇰🇷 · Shin Hyung Kim🇯🇵 · Seung-il Nam🇰🇷 · Myung-Ki Cheoun🇰🇷
We investigate double-strangeness exchange reactions, $K^{-} p \to K^{+} Ξ^{-}$ and $K^{-} p \to K^{0} Ξ^{0}$ , using an effective Lagrangian approach based on a hybrid Regge-plus-resonance model involving rescattering diagrams. We consider the background processes that include $Λ$ , $Σ$ , and $Σ (1385)$ Regge trajectories in the $u$ channel and the $s$ -channel Born-term diagrams. The $s$ -channel hyperon resonances account for the bump structures in the total cross sections. The $s$ -channel $Λ (2100, 7/ 2^{-})$ and $Σ (2030, 7/ 2^{+})$ resonances contribute significantly, and the $Σ (2250)$ resonance favors $J^{P} = 7/ 2^{-}$ . The interference pattern between the $Λ (2100, 7/ 2^{-})$ and $Σ (2030, 7/ 2^{+})$ amplitudes is essential for describing forward differential cross sections in the resonance region $2.07 < s < 2.15$ GeV. The absence of the $S = - 2$ meson leads to the inclusion of the meson-baryon rescattering diagrams to describe the $K^{-} p \to K Ξ$ reaction data, proving the significant contribution of the $(ϕ, ρ, ω)$ -- $(Λ, Σ)$ rescattering diagrams.
nucl-thhep-phPRC(2023)·10 citations
05
Inverse Potentials for all l-channels of Neutron-Proton Scattering using Reference Potential Approach
Anil Khachi · Lalit Kumar · Ayushi Awasthi · O. S. K. S. Sastri
Reference potential approach (RPA) is successful in obtaining inverse potentials for weakly bound diatomic molecules using Morse function. In this work, our goal is to construct inverse potentials for all available l-channels of np-scattering using RPA. The Riccati-type phase equations for various l-channels are solved using 5th order Runge-Kutta method to obtain scattering phase shifts (SPS) in tandem with an optimization procedure to minimize mean squared error (MSE). Interaction potentials for a total of 18 states have been constructed using only three parameter Morse interaction model. The obtained MSE is < 1% for 1S0 , 3P1 and 3D1 channels and < 2% for 1P1 channel and < 0.1% for rest of the 14 channels. The obtained total scattering cross-sections at various lab energies are found to be matching well with experimental ones. This phase wave analysis study of all channels of np-scattering using RPA has been undertaken using Morse function as zeroth reference, by us, is for the first time.
nucl-thPhys.Scripta(2023)·21 citations
06
Tabulated Equations of State From Models Informed by Chiral Effective Field Theory
Mark G. Alford🇺🇸 · Liam Brodie🇺🇸 · Alexander Haber🇺🇸 · Ingo Tews🇺🇸
We construct four equation of state (EoS) tables, tabulated over a range of temperatures, densities, and charge fractions, relevant for neutron star applications such as simulations of neutron star mergers. The EoS are computed from a relativistic mean-field theory constrained by the pure neutron matter EoS from chiral effective field theory, inferred properties of isospin-symmetric nuclear matter, and astrophysical observations of neutron star structure. To model nuclear matter at low densities, we attach an EoS that models inhomogeneous nuclear matter at arbitrary temperatures and charge fractions. The four EoS tables we develop are available from the CompOSE EoS repository compose.obspm.fr/eos/297 and gitlab.com/ahaber/qmc-rmf-tables.
nucl-thastro-ph.HEhep-phPhys.Scripta(2023)·17 citations
07
Revisiting the Lithium abundance problem in Big-Bang nucleosynthesis
Vinay Singh · Debasis Bhowmick · D. N. Basu
One of the three testaments in favor of the big bang theory is the prediction of the primordial elemental abundances in the big-bang nucleosynthesis (BBN). The Standard BBN is a parameter-free theory due to the precise knowledge of the baryon-to-photon ratio of the Universe obtained from studies of the anisotropies of cosmic microwave background radiation. Although the computed abundances of light elements during primordial nucleosynthesis and those determined from observations are in good agreement throughout a range of nine orders of magnitude, there is still a disparity of $^{7}$ Li abundance overestimated by a factor of $\sim 2.5$ when calculated theoretically. The number of light neutrino flavors, the neutron lifetime and the baryon-to-photon ratio in addition to the astrophysical nuclear reaction rates determine the primordial abundances. We previously looked into the impact of updating baryon-to-photon ratio and neutron lifetime and changing quite a few reaction rates on the yields of light element abundances in BBN. In this work, calculations are performed using new reaction rates for $^{3}$ H(p, $γ$ ) $^{4}$ He, $^{6}$ Li(p, $γ$ ) $^{7}$ Be, $^{7}$ Be(p, $γ$ ) $^{8}$ B, $^{13}$ N(p, $γ$ ) $^{14}$ O, $^{7}$ Li(n, $γ$ ) $^{8}$ Li and $^{11}$ B(n, $γ$ ) $^{12}$ B along with the latest measured value of neutron lifetime. We observe from theoretical calculations that these changes result in improvement by causing further reduction in the abundance of $^{7}$ Li than calculated earlier.
nucl-thastro-ph.COAstropart.Phys.(2024)·8 citations
08
Quarkyonic Model for Neutron Star Matter: A Relativistic Mean-Field Approach
Ankit Kumar🇮🇳 · Debabrata Dey🇮🇳 · Shamim Haque🇮🇳 · Ritam Mallick🇮🇳 · S. K. Patra🇮🇳
The concept of quarkyonic matter presents a promising alternative to the conventional models used to describe high-density matter and provides a more nuanced and detailed understanding of the properties of matter under extreme conditions that exist in astrophysical bodies. The aim of this study is to showcase the effectiveness of utilizing the quarkyonic model, in combination with the relativistic mean-field formalism, to parameterize the equation of state at high densities. Through this approach, we intend to investigate and gain insights into various fundamental properties of a static neutron star, such as its compositional ingredients, speed of sound, mass-radius profile, and tidal deformability. The obtained results revealed that the quarkyonic matter equation of state (EOS) is capable of producing a heavy neutron star with the mass range of $\sim$ $2.8 M_{⊙}$ . The results of our inquiry have demonstrated that the EOS for quarkyonic matter not only yields a neutron star with a significantly high mass but also showcases a remarkable degree of coherence with the conformal limit of the speed of sound originating from deconfined QCD matter. Furthermore, we have observed that the tidal deformability of the neutron star, corresponding to the EOSs of quarkyonic matter, is in excellent agreement with the observational constraints derived from the GW170817 and GW190425 events. This finding implies that the quarkyonic model is capable of forecasting the behavior of neutron stars associated with binary merger systems. This aspect has been meticulously scrutinized in terms of merger time, gravitational wave signatures, and collapse times using numerical relativity simulations.
nucl-thastro-ph.HE11 citations
09
Heavy baryon spectroscopy in a quark-diquark approach
A. Torcato🇵🇹 · A. Arriaga🇵🇹 · G. Eichmann🇦🇹 · M. T. Peña🇵🇹
We report progress on calculations of the heavy-light baryons $Σ_{c}$ and $Λ_{c}$ and their excitations with $J^{P} = 1/ 2^{+}$ using functional methods. We employ a covariant quark-diquark approach, where the interaction amounts to a quark exchange between quarks and diquarks and the ingredients are determined from the quark level. A partial-wave analysis reveals the presence of orbital angular momentum components in terms of p waves, which are non-relativistically suppressed.
↳ hep-phhep-latnucl-thFew Body Syst.(2023)·9 citations
10
Evidence of the Schwinger mechanism from lattice QCD
Mauricio Narciso Ferreira🇪🇸
In quantum chromodynamics (QCD), gluons acquire a mass scale through the action of the Schwinger mechanism. This mass emerges as a result of the dynamical formation of massless bound-states of gluons which manifest as longitudinally coupled poles in the vertices. In this contribution, we show how the presence of these poles can be determined from lattice QCD results for the propagators and vertices. The crucial observation that allows this determination is that the Schwinger mechanism poles induce modifications, called ``displacements'', to the Ward identities (WIs) relating two- and three-point functions. Importantly, the displacement functions correspond precisely to the Bethe-Salpeter amplitudes of the massless bound-states. We apply this idea to the case of the three-gluon vertex in pure Yang-Mills SU(3). Using lattice results in the corresponding WI, we find an unequivocal displacement and show that it is consistent with the prediction based on the Bethe-Salpeter equation.
↳ hep-lathep-phhep-thnucl-thFew Body Syst.(2023)·1 citation
11
First characterization of the scattering length distribution of vector meson interaction with deuteron
Xiao-Yun Wang🇨🇳 · Chen Dong🇨🇳 · Quanjin Wang🇨🇳
Under the framework of the vector meson dominance model (VMD), the absolute scattering lengths of light vector mesons ( $ϕ$ , $ω$ , and $ρ$ ) with the deuteron are calculated from the cross sections of vector meson photoproduction off a deuteron. Additionally, a fitting function is used to predict the scattering lengths of the heavy vector mesons $J / ψ$ - $d$ and - $d$ . Based on these results, the distribution of the scattering lengths $∣ α_{V d} ∣$ between vector mesons and the deuteron is presented for the first time and compared with the scattering lengths $∣ α_{V p} ∣$ between vector mesons and the proton. It is found that as the mass of the vector meson increases, the scattering lengths $∣ α_{V d} ∣$ become closer to $∣ α_{V p} ∣$ . In addition, the correlation analysis indicates a strong positive relationship between the scattering length and the vector meson radius, with a high correlation coefficient. The implications of results are essential for improving our understanding of the interaction between hadron and nucleus.
↳ hep-phnucl-thPRC(2023)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE