Nuclear Theory·nucl-th

Monday·August 21, 2023

17 papers—8 primary·9 cross-listed

01
Novel approach to the removal of the Pauli-forbidden states in the orthogonality condition model: A case of multi- $α$ systems
H. Moriya · W. Horiuchi · B. Zhou
We propose to use a basis function constructed based on the microscopic cluster model for an efficient description of multi-cluster systems with the orthogonality condition originating from the Pauli principle. The basis function is expressed analytically by a superposition of correlated Gaussian functions. We demonstrate the power of this approach by taking an example of a $3 α$ system, $^{12}$ C. A comparison with the conventional pseudopotential method using the projection operator is made. The present method offers efficient and numerically stable computations as the number of basis functions is significantly reduced compared to the conventional method. We show that the present basis function includes reasonably small components of the Pauli-forbidden states, allowing us to discuss simply the structure of the first excited $0^{+}$ state, Hoyle state.
nucl-thEPJA(2023)·2 citations
02
Nuclear matrix elements calculation for $0 ν β β$ decay of $^{124}$ Sn using nonclosure approach in nuclear shell model
Shahariar Sarkar🇮🇳 · P. K. Rath🇮🇳 · V. Nanal🇮🇳 · R. G. Pillay🇮🇳 · Pushpendra P. Singh🇮🇳 · Y. Iwata🇯🇵 · K. Jha🇮🇳 · P. K. Raina🇮🇳
In this study, we calculate the nuclear matrix elements (NMEs) for the light neutrino-exchange mechanism of neutrinoless double beta $0 ν β β$ ) decay of $^{124}$ Sn within the framework of the interacting nuclear shell model using the effective shell model Hamiltonian GCN5082. A novel method based on a nonclosure approach is employed, wherein for the intermediate nucleus $^{124}$ Sb, effects of energy of 100 states for each $J_{k}^{π}$ = $0^{+}$ to $1 1^{+}$ and $2^{-}$ to $9^{-}$ ( $Δ J_{k}$ =1) are explicitly included in the NMEs calculation. Other common effects such as the finite size of nucleons, higher-order effects of nucleon currents, and short-range correlations (SRC) of nucleons are also taken into account. The extracted optimal closure energy is 2.9 MeV for a total NME of $^{124}$ Sn $0 ν β β$ decay, which is independent of different forms of SRC parametrizations. A comparison of NMEs and half-lives with some of the recent calculations is presented. Further, to gain a comprehensive understanding of the role of nuclear structure on the $0 ν β β$ decay, the dependence of NMEs on spin-parity of the intermediate states, coupled spin-parity of neutrons and protons, and the number of intermediate states, is explored. It is observed that the inclusion of the effects of excitation energies of the intermediate nucleus yields more reliable NMEs. The present findings provide valuable insights for experimental investigations of $0 ν β β$ decay of $^{124}$ Sn in India and elsewhere.
nucl-thPRC(2024)·4 citations
03
Tetrahedral shape of $^{110}$ Zr from covariant density functional theory in 3D lattice space
Fangfang Xu · Bo Li · Zhengxue Ren · Pengwei Zhao
Covariant density functional theory is solved in 3D lattice space by implementing the preconditioned conjugate gradient method with a filtering function (PCG-F). It considerably improves the computational efficiency compared to the previous inverse Hamiltonian method (IHM). This new method is then applied to explore the tetrahedral shape of $^{110}$ Zr in the full deformation space. The ground state of $^{110}$ Zr is found to have a tetrahedral shape, but the deformations $β_{31}$ and $β_{33}$ greatly soften the potential energy surface. This effect is analysed with the microscopic evolution of the single-particle levels near the Fermi surface driven by the deformation.
nucl-thPRC(2024)·23 citations
04
Excluded Volume Effects on Cold Neutron Star Phenomenology
Jesper Leong🇦🇺 · Anthony W. Thomas🇦🇺 · Pierre A. M. Guichon🇫🇷
Observable properties of neutron stars are studied within a hadronic equation of state derived from the quark level. The effect of short-range repulsion is incorporated within the excluded volume framework. It is found that one can sustain neutron stars with masses as large as 2.2 $M_{⊙}$ even including hyperons in $β$ equilibrium, while producing radii and tidal deformabilities consistent with current constraints.
nucl-thastro-ph.HEhep-phNPA(2024)·9 citations
05
Probing the impact of Delta-Baryons on Nuclear Matter and Non-Radial Oscillations in Neutron Stars
Probit Jyoti Kalita🇮🇳 · Pinku Routaray🇮🇳 · Sayantan Ghosh🇮🇳 · Bharat Kumar🇮🇳 · Bijay K. Agrawal🇮🇳
The presence of heavy baryons, such as $Δ$ -baryons and hyperons can significantly impact various properties of Neutron Stars (NSs), like oscillation frequencies, dimensionless tidal deformability, mass, and radii. We explored these effects within the Density-Dependent Relativistic Mean Field formalism. Our analysis considered $Δ$ -admixed NS matter in both hypernuclear and hyperon-free scenarios, providing insights into particle compositions and their effects on NS properties. Our study of non-radial $f$ -mode oscillations revealed a distinct increase in frequency due to the additional baryons. The degree of increase was significantly influenced by the meson-baryon coupling strengths. Notably, the coupling between $Δ$ -resonances and $σ$ -mesons played a highly influential role. In some cases, it led to an approximately 20\% increase in the $f$ -mode oscillation frequency of canonical NSs. These couplings also affect other bulk properties of NSs, including mass, radii, and dimensionless tidal deformability ( $Λ$ ). Comparing our results with available observational data from pulsars (NICER) and gravitational waves (LIGO-VIRGO collaboration), we found strong agreement, particularly concerning $Λ$ .
nucl-thgr-qcJCAP(2024)·7 citations
06
Unified description of superconductivity in neutron stars
Dmitry Kobyakov
In this paper, I study the location and symmetry of superconducting protons. Solving the Tolman-Oppenheimer-Volkoff (TOV) equations based on the unified Barcelona-Catania-Paris-Madrid equation of state (BCPM EoS) and on the pairing gap calculations by Lim and Holt [1], I find that roughly 500 meters of the liquid core (with isotropic and continuous symmetry) and roughly 100-150 meters of the core-crust interface (with anisotropic symmetry) are superconducting, while the rest of the star is normal. To specify whether the superconducting symmetry is discreet in the pasta phase, I study the coexistence of the saturated nuclear and the pure neutron matter using EoS based on the chiral effective field theory (ChEFT). I find that the maximum pressure at coexistence is $P_{*} ≃ 0.5 MeV f m^{- 3}$ . To verify the precision of the coexistence calculations I evaluate the surface and the Coulomb corrections using the compressible liquid drop model. I calculate the proton tunneling rate in the perfectly ordered slab region of the pasta phase and conclude that for the chosen EoS, the proton supercurrent tunneling between the adjacent slabs is negligible and the slab region should be described as a discreet symmetry system of quasi two-dimensional layers.
nucl-thastro-ph.HEcond-mat.supr-conarXiv preprint 2024·1 citation
07
An alternative scheme for pionless EFT: neutron-deuteron scattering in the doublet S-wave
M. Ebert🇩🇪 · H.-W. Hammer🇩🇪 · A. Rusetsky🇩🇪
Using the effective-range expansion for the two-body amplitudes may generate spurious sub-threshold poles outside of the convergence range of the expansion. In the infinite volume, the emergence of such poles leads to the breakdown of unitarity in the three-body amplitude. We discuss the extension of our alternative subtraction scheme for including effective range corrections in pionless effective field theory for spinless bosons to nucleons. In particular, we consider the neutron-deuteron system in the doublet S-wave channel explicitly.
nucl-thhep-latFew Body Syst.(2023)·4 citations
08
Sequential decays of the triple strange process $p ˉ p \to Ω ˉ^{+} Ω^{-} \to K^{+} Λ ˉ K^{-} Λ \to K^{+} p ˉ π^{+} K^{-} p π^{-}$ : a model-independent approach
Deepak Pachattu🇮🇳
A model-independent irreducible tensor formalism is developed to analyse $Ω ˉ Ω$ production in $p ˉ p$ collisions and its subsequent decay via the triple-strange decay process, $Ω ˉ^{+} Ω^{-} \to K^{+} Λ ˉ K^{-} Λ \to K^{+} p ˉ π^{+} K^{-} p π^{-}$ . These processes are relevant for the upcoming experiments at PANDA. We not only provide expressions for the density matrix of the $Ω Ω ˉ$ system but also for the products at each stage of the decay. The Fano statistical tensors so obtained not only completely characterize the relevant final systems but also provide expressions for joint angular distributions. Finally, we show which of the Fano statistical tensors characterizing the $Ω ˉ Ω$ system can be inferred from the Fano statistical tensors characterizing the final $p ˉ p$ system, wherein we also obtain the relation between the production cross sections for $Ω Ω ˉ$ and the final $p p ˉ$ system.
nucl-thhep-phnucl-exNPA(2024)·1 citation
09
Finite System Size Correction to the Effective Coupling in $ϕ^{4}$ Scattering
W. A. Horowitz🇿🇦 · J. F. Du Plessis🇿🇦
We compute and explore numerically the finite system size correction to NLO $2 \to 2$ scattering in massive scalar $ϕ^{4}$ theory. The derivation uses "denominator regularization" (instead of the usual dimensional regularization) on a spacetime with spatial directions compactified to a torus, with characteristic lengths not necessarily of equal size. We determine a useful analytic continuation of the generalized Epstein zeta function to isolate the usual UV divergence. Self-consistently, the renormalized finite system size correction reduces to zero as the system size goes to infinity and, further, satisfies the optical theorem. One of our checks of unitarity leads to a generalization of a number theoretic result from Hardy and Ramanujan. Precise numerical exploration of the finite system size correction to the amplitude and coupling when two spatial dimensions are finite requires the exploitation of the analytic structure of the finite system size result via a dispersion relation. We find that the finite system size scattering amplitude exhibits "geometric" bound states. Even away from these bound states, the finite system size correction to the effective coupling can be large.
↳ hep-thhep-phnucl-thPRD(2024)·1 citation
10
Compositeness of near-threshold exotic hadrons with decay and coupled-channel effects
Tomona Kinugawa🇯🇵 · Tetsuo Hyodo🇯🇵
The near-threshold exotic hadrons such as $T_{cc}$ and $X (3872)$ are naively considered as the hadronic molecular state from the viewpoint of the low-energy universality. However, it is also known that the elementary dominant state is not completely excluded as the internal structure of the near-threshold states. Furthermore, the dominance of molecules is expected to be modified by the decay or coupled channels. We discuss these features of the near-threshold bound states by calculating the compositeness with the effective field theory.
↳ hep-phnucl-thEPJ Web Conf.(2024)·0 citations
11
Associated vector meson and bound-free electron-positron pair photoproduction in ultraperipheral $P b P b$ collisions
Celsina N. Azevedo🇧🇷 · Victor P. Goncalves🇧🇷 · Bruno D. Moreira🇧🇷
In this letter we analyze the associated production of a vector meson with the bound - free $e^{+} e^{-}$ process in ultraperipheral $P b P b$ collisions through the double scattering mechanism for the energy of the Large Hadron Collider (LHC). Such process is characterized by the presence of a meson and a positron in the final state and by a forward hydrogen - like ion with a distinct electric charge. We present our predictions for the total cross sections and rapidity distributions considering the rapidity ranges covered by the ALICE and LHCb detectors, which indicate that a future experimental analysis of the $ϕ + e^{+}$ and $J /Ψ + e^{+}$ final states is feasible.
↳ hep-phnucl-thPRC(2023)·2 citations
12
Deep Exclusive Meson Production as a probe to the puzzle of $Λ$ hyperon polarization
Zhoudunming Tu🇺🇸
In the 1970s, an unexpected transverse $Λ$ polarization in unpolarized proton-Beryllium collisions was discovered, which initiated extensive studies on spin phenomena in high-energy physics. Over the past five decades, similar transverse $Λ$ polarization has been observed across various collision systems, including lepton-hadron deep inelastic scattering, hadron-hadron collisions, and electron-positron collisions. Despite numerous promising theoretical models, the fundamental mechanism underlying this polarization phenomenon remains inconclusive to this day. However, in both longitudinally and transversely polarized lepton-hadron and hadron-hadron collisions, it is found that the $Λ$ hyperon is not polarized with respect to the initial parton spin direction. How the $Λ$ hyperon acquires its spin has become one of the most crucial questions to address in order to resolve this puzzle. In this paper, I propose to use an exclusive process that can be measured at the Electron-Ion Collider, the Deep Exclusive Meson Production, to explicitly test the mechanism of $Λ$ polarization. The outcomes of this experimental measurement are anticipated to unveil the dominant mechanism by which $Λ$ obtains its spin, eliminating many of the ambiguities that have been encountered in previous studies. Finally, experimental challenges and requirements will be discussed.
↳ hep-phhep-exnucl-exnucl-thPRC(2024)·11 citations
13
Atmospheric Effects on Neutron Star Parameter Constraints with NICER
Tuomo Salmi🇳🇱 · Serena Vinciguerra🇳🇱 · Devarshi Choudhury🇳🇱 · Anna L. Watts🇳🇱 · Wynn C. G. Ho🇺🇸 · Sebastien Guillot🇫🇷 · Yves Kini🇳🇱 · Bas Dorsman🇳🇱 · Sharon M. Morsink🇨🇦 · Slavko Bogdanov🇺🇸
We present an analysis of the effects of uncertainties in the atmosphere models on the radius, mass, and other neutron star parameter constraints for the NICER observations of rotation-powered millisecond pulsars. To date, NICER has applied the X-ray pulse profile modeling technique to two millisecond-period pulsars: PSR J0030+0451 and the high-mass pulsar PSR J0740+6620. These studies have commonly assumed a deep-heated, fully ionized hydrogen atmosphere model, although they have explored the effects of partial-ionization and helium composition in some cases. Here, we extend that exploration and also include new models with partially ionized carbon composition, externally heated hydrogen, and an empirical atmospheric beaming parameterization to explore deviations in the expected anisotropy of the emitted radiation. None of the studied atmosphere cases have any significant influence on the inferred radius of PSR J0740+6620, possibly due to its X-ray faintness, tighter external constraints, and/or viewing geometry. In the case of PSR J0030+0451, both the composition and ionization state could significantly alter the inferred radius. However, based on the evidence (prior predictive probability of the data), partially ionized hydrogen and carbon atmospheres are disfavored. The difference in the evidence for ionized hydrogen and helium atmospheres is too small to be decisive for most cases, but the inferred radius for helium models trends to larger sizes around or above 14-15 km. External heating or deviations in the beaming that are less than $5 %$ at emission angles smaller than 60 degrees, on the other hand, have no significant effect on the inferred radius.
↳ astro-ph.HEastro-ph.SRnucl-thApJ(2023)·41 citations
14
Proton number cumulants in a modified van der Waals hadron resonance gas
Kshitish Kumar Pradhan🇮🇳 · Ronald Scaria🇮🇳 · Dushmanta Sahu🇮🇳 · Raghunath Sahoo🇮🇳
An estimate of the proton number cumulants in the hadronic matter is presented considering a van der Waals-type interaction between the constituent particles. We argue that the attractive and repulsive parameters in the VDW hadron resonance gas (VDWHRG) model change as functions of baryochemical potential ( $μ_{B}$ ) and temperature ( $T$ ). This, in turn, affects the estimation of thermodynamic properties and, consequently, the conserved charge fluctuations. We employ a simple parametrization to bring in the center-of-mass energy ( $s_{NN}$ ) dependence on temperature and baryochemical potential and then estimate the proton number cumulants with the modified approach. The modified van der Waals hadron resonance gas model (MVDWHRG) explains the existing experimental data very well.
↳ hep-phhep-exnucl-exnucl-th5 citations
15
$K^{+} N$ elastic scatterings for estimation of in-medium quark condensate with strange quarks
Yutaro Iizawa🇯🇵 · Daisuke Jido🇯🇵 · Stephan Hübsch🇯🇵
We revisit the low-energy $K^{+} N$ elastic scatterings in the context of the in-medium quark condensate with strange quarks. The chiral ward identity connects the in-medium quark condensate to the soft limit value of the pseudoscalar correlation function evaluated in nuclear matter. The in-medium correlation function of the psuedoscalar fields with strangeness describes in-medium kaon propagation and is obtained by kaon-nucleon scattering amplitudes in the low density approximation. We construct the kaon-nucleon scattering amplitudes in chiral perturbation theory up to the next-to-leading order and add some terms of the next-to-next-to-leading order with the strange quark mass to improve expansion of the strange quark sector. We also consider the effect of a possible broad resonance state around $P_{lab} = 600$ MeV/c for $I = 0$ reported in the previous study. The low energy constants are determined by existent $K^{+} N$ scattering data. We obtain good reproduction of the $K^{+} p$ scattering amplitude by chiral perturbation theory, while the description of the $K N$ amplitude with $I = 0$ is not so satisfactory due to the lack of low energy data. Performing analytic continuation of the scattering amplitudes obtained by chiral perturbation theory to the soft limit, we estimate the in-medium strange quark condensate.
↳ hep-phnucl-exnucl-thPTEP(2024)·5 citations
16
An updated mass-radius analysis of the 2017-2018 NICER data set of PSR J0030+0451
Serena Vinciguerra · Tuomo Salmi · Anna L. Watts · Devarshi Choudhury · Thomas E. Riley · Paul S. Ray · Slavko Bogdanov · Yves Kini · Sebastien Guillot · Deepto Chakrabarty · Wynn C. G. Ho · Daniela Huppenkothen · Sharon M. Morsink · Zorawar Wadiasingh
In 2019 the NICER collaboration published the first mass and radius inferred for PSR J0030+0451, thanks to NICER observations, and consequent constraints on the equation of state characterising dense matter. Two independent analyses found a mass of $\sim 1.3 - 1.4 M_{⊙}$ and a radius of $\sim 13$ km. They also both found that the hot spots were all located on the same hemisphere, opposite to the observer, and that at least one of them had a significantly elongated shape. Here we reanalyse, in greater detail, the same NICER data set, incorporating the effects of an updated NICER response matrix and using an upgraded analysis framework. We expand the adopted models and jointly analyse also XMM-Newton data, which enables us to better constrain the fraction of observed counts coming from PSR J0030+0451. Adopting the same models used in previous publications, we find consistent results, although with more stringent inference requirements. We also find a multi-modal structure in the posterior surface. This becomes crucial when XMM-Newton data is accounted for. Including the corresponding constraints disfavors the main solutions found previously, in favor of the new and more complex models. These have inferred masses and radii of $\sim [1.4 M_{⊙}, 11.5$ km] and $\sim [1.7 M_{⊙}, 14.5$ km], depending on the assumed model. They display configurations that do not require the two hot spots generating the observed X-rays to be on the same hemisphere, nor to show very elongated features, and point instead to the presence of temperature gradients and the need to account for them.
↳ astro-ph.HEastro-ph.SRnucl-thApJ(2024)·276 citations
17
Emergent interaction-driven elliptic flow of few fermionic atoms
Sandra Brandstetter🇩🇪 · Philipp Lunt🇩🇪 · Carl Heintze🇩🇪 · Giuliano Giacalone🇩🇪 · Lars H. Heyen🇩🇪 · Maciej Gałka🇩🇪 · Keerthan Subramanian🇩🇪 · Marvin Holten🇩🇪 · Philipp M. Preiss🇩🇪 · Stefan Floerchinger🇩🇪 · Selim Jochim🇩🇪
Hydrodynamics provides a successful framework to effectively describe the dynamics of complex many-body systems ranging from subnuclear to cosmological scales by introducing macroscopic quantities such as particle densities and fluid velocities. According to textbook knowledge, it requires coarse graining over microscopic constituents to define a macroscopic fluid cell, which is large compared to the interparticle spacing and the mean free path. In addition, the entire system must consist of many such fluid cells. In high energy heavy ion collisions, hydrodynamic behaviour is inferred from the observation of elliptic flow. Here, we demonstrate the emergence of elliptic flow in a system of few strongly interacting atoms. In our system a hydrodynamic description is a priori not applicable, as all relevant length scales, i.e. the system size, the inter-particle spacing, and the mean free path are comparable. The single particle resolution, deterministic control over particle number and interaction strength in our experiment allow us to explore the boundaries between a microscopic description and a hydrodynamic framework in unprecedented detail.
↳ cond-mat.quant-gasnucl-exnucl-thquant-phNat.Phys.(2025)·36 citations

Affiliations

first authorsco-authorsvia INSPIRE