Nuclear Theory·nucl-th

Wednesday·January 22, 2025

23 papers—9 primary·14 cross-listed

01
Constituent Quark-model for BaryonsTh. Harmonic confinement and Two-body Meson-exchange Potentials
Th.A. Rijken🇳🇱
Soft Two-body potentials between the constituent quarks of the nucleon are derived using harmonic oscillator, i.e. gaussian, quark wave-functions. The gaussian wave-functions are very suited for applications with the ESC soft-core interactions, which employ gaussian form factors. In these notes using the Fourier transformation to momentum space the local and non-local contributions of the potentials based on the ESC meson-quark-quark vertices are evaluated. Using the ESC16 parameters translated to the quark-level leads to parameter free two-body and three-body diquark and triquark meson-exchange interactions. Applications to the SU(3) baryon-octet states and the $Δ_{33}$ resonance are performed., within the CQM using a harmonic confinement potential, leading to a satisfactory picture with relativistic constituent quarks. We present two versioins for the $N - Δ$ splitting: (i) model A with the instanton interaction, and (ii) model B with a large color-magnetic interaction from an almost point like OGE. The size of the baryons $\approx$ 1 fm.
nucl-thhep-ph0 citations
02
Unnuclear matter at large-charge
Silas R. Beane🇨🇭 · Domenico Orlando🇨🇭 · Susanne Reffert🇨🇭
The utility of the non-relativistic large-charge EFT for physical systems, and neutron matter in particular, relies on controlled Schrödinger-symmetry breaking deformations due to scattering length and effective-range effects in the two-body system. A recently-found exact solution of the large-charge system is used to compute these effects for two-point correlation functions of large-charge operators in perturbation theory around the large-charge ground state. Notably, the leading effective-range effects are found to enter at second order in the effective range, in agreement with analogous calculations in the three-body system. The Schrödinger-symmetry breaking deformations are used -- together with input from Quantum Monte Carlo simulations -- to address the range of validity of the EFT with deformations both in general and in the special case of neutron matter. In particular, it is found that nuclear reactions with up to six low-energy neutrons in the final state can be described by the large-charge EFT with Schrödinger-symmetry breaking.
nucl-thhep-phhep-thPRD(2025)·5 citations
03
The 3 $α$ correlations of ground and excited $0^{+}$ states of $^{12} C$ within the microscopic cluster model
De-Ye Tao · Bo Zhou · Yu-Gang Ma
The cluster structures of the $0^{+}$ states in $^{12} C$ , including the ground state, the Hoyle state, and the recently identified $0_{3}^{+}$ and $0_{4}^{+}$ states, are analyzed to explore the cluster configurations and $3 α$ correlations without assuming the existence of $^{8} Be$ . In particular, the key quantity -- two-cluster overlap amplitudes -- is calculated for the $3 α$ clustering channels to reveal the essential features of these $0^{+}$ states. The results clearly show the distinction between the compact structure of the ground state and the gas-like structures of the excited $0^{+}$ states. The Hoyle state exhibits the expected gas-like dominant ( $0 S$ ) configuration, while the $0_{3}^{+}$ state shows a more extended $3 α$ clustering structure, which can be viewed as a breathing-like excitation of the Hoyle state, with an additional nodal structure. The $0_{4}^{+}$ state is found to have a mixed configuration, featuring a bent-arm-like structure in the $S \otimes S$ channel and an enhanced $2 α$ correlation in the $D \otimes D$ channel.
nucl-thPRC(2025)·5 citations
04
Typical new spherical-like $γ$ -soft spectra in $^{104, 106, 108}$ Pd
Tao Wang
To solve the Cd puzzle (spherical nucleus puzzle), I have proposed a new spherical-like $γ$ -soft nucleus. Since shape coexistence often occurs in such nuclei, explicit spherical-like $γ$ -soft spectra are not easily identified. In this paper, I finally find the direct evidence for the existence of the new spherical-like $γ$ -soft nucleus. $^{106}$ Pd is in fact a typical spherical-like $γ$ -soft nucleus. The low-lying parts, up to the $1 0_{1}^{+}$ state, under 4000 keV, of the spherical-like $γ$ -soft spectra are verified. The B(E2) values and the quadrupole moments of the low-lying levels are also studied. By comparison, the new spherical-like $γ$ -soft mode is confirmed. Moreover $^{104, 108}$ Pd are also discussed. These results completely disprove the possibility of the phonon excitations of the spherical nucleus in the Cd-Pd nuclei region.
nucl-th4 citations
05
Some insights on the partonic collectivity in heavy-ion collisions
Rajeev Singh🇷🇴
Elliptic flow and Number of Constituent Quarks scaling provide crucial insights into the underlying dynamics and degrees of freedom in heavy-ion collisions. This article provides some insights on the transition from hadronic to partonic collectivity, revealing possible key signatures of medium evolution. At low energies around ( $s_{NN} \leq 4.0$ GeV), $v_{2}$ may be negative and NCQ scaling might break down. We expect that as the collision energy rises beyond 4.0 GeV, $v_{2}$ may become positive and NCQ scaling gradually restores. The transition in $v_{2}$ behavior, coupled with the breakdown and restoration of NCQ scaling, highlights the increasing significance of partonic interactions at higher energies, marking the onset of partonic collectivity and the emergence of quark-gluon plasma (QGP)-like properties.
nucl-thhep-phSpringer Proc.Phys.(2026)·1 citation
06
Complex-scaled no-core shell model calculations of bound and unbound nuclear states in light nuclei
A.T. Kruppa · N. Michel · Xin-le Shang · Wei Zuo
The complex scaling method is commonly used to describe decaying states, but its applications are limited because the Hamiltonian operator must contain only relative coordinates. This has hindered the use of complex scaling in models defined with laboratory single-particle coordinates, and in particular one of the most important model in low-energy nuclear physics, the no-core shell model. We will then present a straightforward procedure for introducing complex scaling in the no-core shell model in order to calculate nuclear resonance states. For that matter, the complex-scaled two-body matrix elements must firstly be determined, and the resulting many-body Hamiltonian complex symmetric matrix must be diagonalized afterwards. Applications pertain to the bound ground states of the lightest nuclei $^{2} H$ , $^{3} H$ , $^{3} He$ , and $^{4} He$ , as well as the resonance ground states of $^{5}$ He and $^{5}$ Li, whereby the realistic interaction Daejeon16 is utilized.
nucl-thPRC(2026)·3 citations
07
Dynamical Electromagnetic fields and Dynamical Electromagnetic Anomaly in heavy ion collisions at intermediate energies
Irfan Siddique🇨🇳 · Anping Huang🇨🇳 · Mei Huang🇨🇳 · Muhammad Abdul Wasaye🇨🇳
Electromagnetic field produced in non-central heavy ion collisions play a crucial role in phenomena such as chiral anomalous effects, directed flow of mesons and splitting of spin polarization of $Λ/ Λ ˉ$ . A precise description of these fields is essential for quantitatively studying these effects. We investigate the space-time evolution of the electromagnetic fields by numerically solving Maxwell's equations using the results from the UrQMD model, rather than relying on an ansatz. We present the space-averaged dynamic electromagnetic fields, weighted by energy density, in the central region of heavy-ion collisions. These measurements can serve as a barometer for assessing the effects induced by magnetic fields. Comparing the fields at geometric center of the collisions, the space-averaged dynamical fields weighted by the energy density are smaller at the early stage but damp much slower at the later stage. We discuss the impact of these space averaged dynamical magnetic fields on the spin polarization and spin alignment in heavy ion collisions. Additionally, we explore the opportunity to study non-perturbative regime of Quantum Electrodynamics (QED) by presenting the simulation results for space averaged dynamical electric field at intermediate collision energies. Finally, the space-averaged dynamical electromagnetic anomaly $E$ $\cdot B$ weighted by energy density is also calculated and compared with experimentally measured slope parameter $r$ .
nucl-thhep-phPRC(2025)·4 citations
08
Beta-delayed particle emission and collective rotations
K. Riisager · E.A.M. Jensen · A.S. Jensen
Beta-delayed proton emission in the lower half of the sd-shell will involve deformed nuclei. We derive the normalized matrix element connecting emission of one particle from an initial rotational nuclear state to another final rotating state, and we extract selection rules involving the $K$ quantum number. The initial state is approximated as having a core identical to the final nuclear state. The formalism is then directly applicable to $β^{+}$ -delayed proton decays of even- $Z$ , odd- $N$ nuclei or $β^{-}$ -delayed neutron decays of odd- $Z$ , even $N$ nuclei. These beta-decay results are compared to the outcomes of possible transfer reactions. As an example the beta-delayed proton emission of $^{21}$ Mg is considered, where new quantum numbers can be assigned to several states in $^{21}$ Na.
nucl-thnucl-exEPJA(2025)·0 citations
09
Light clusters as a possible source of crustal impurities: a quasi-particle approach
Helena Pais🇵🇹 · Hoa Dinh-Thi🇺🇸 · Anthea F. Fantina🇫🇷 · Francesca Gulminelli🇫🇷 · Constança Providência🇵🇹
The presence of impurities in the neutron star crust is known to affect in an important way the thermal and electrical conductivity of the star. In this work, we explore the possibility that such impurities might arise from the simultaneous presence of heavy ions together with Hydrogen and Helium isotopes formed during the cooling process of the star. We consider an equilibrium population of such light particles at temperatures close to the crystallization of the crust within an effective quasi-particle approach including in-medium binding energy shifts, and using different versions of the relativistic mean field approach for the crustal modeling. Thermal effects are consistently included also in the dominant ion species present in each crustal layer described in the compressible liquid drop approximation. We find that the impurity factor associated to light clusters is comparatively very small and can be neglected in transport calculations, even if a strong model dependence is observed.
nucl-thastro-ph.HEAstron.Astrophys.(2025)·1 citation
10
Excited s-wave $1^{--}$ vector mesons, their leptonic decays and (in-)complete absence of abnormal states as seen from the constituent quark BSE
V. Sauli🇨🇿
Within a lattice inspired interaction between quark and antiquark, we obtain a hierarchy of solutions to the Bethe-Salpeter equation (BSE) for vector quarkonia excited states in the constituent quark mass approximation. As a toy model, we apply the similar to calculate ground and excited states of $ϕ$ and $ω / ρ$ meson. Through detailed numerical searches, our study provides evidence that the single-valued constant mass quark propagator does not yield known meson spectra without the simultaneous presence of abnormal (unphysical) solutions. We classify normal and abnormal solutions and discuss necessary changes in the calculation scheme to avoid the spectrum of inconsistent solutions. While all experimental narrow vector mesons are identified with a normal state of the BSE, the occurrence of mutually cancelled normal-abnormal states are reported. The results are slightly different for the heavy and light mesons, but in both cases they seem to result from the inconsistent use of the hmogeneous BSE to describe broad resonances.
↳ hep-phhep-exnucl-thNPA(2025)·1 citation
11
The role of the chiral anomaly in polarized deeply inelastic scattering III: Wess-Zumino-Witten contributions and chiral Ward identities for finite quark mass
Andrey Tarasov🇺🇸 · Raju Venugopalan🇺🇸
We extend our prior results on the worldline computation of the axial vector-vector-vector (AVV) triangle anomaly in polarized deeply inelastic scattering (DIS) to the finite mass case by computing in addition the pseudoscalar-vector-vector (PVV) triangle graph. For the well-studied QED case, we show explicitly how the off-forward AVV pole exactly cancels an identical PVV pole. We then demonstrate the dramatic difference in QCD due to the chiral condensate, which qualitatively modifies anomalous Ward identities. As in the massless case, the anomaly pole in QCD is canceled by the dynamics of a primordial isosinglet pseudoscalar $η ˉ$ -meson, whose Wess-Zumino-Witten coupling to the topological charge density shifts the pole to the physical $η^{'}$ mass, with the finite quark mass contribution differing by $O (10%)$ from the Witten-Veneziano formula. We obtain a compact analytic expression for the finite mass corrections to Shore and Veneziano's result that the proton's net quark helicity $ΔΣ \propto χ_{QCD}^{'} ∣_{m = 0} (0)$ , the forward slope of the topological susceptibility in the chiral limit, and show they are of the order of a few percent. Our prior prediction that the polarized DIS structure function $g_{1}$ is quenched by sphaleron-like topological transitions at small $x$ is unaffected by quark mass effects. Our results illustrate how worldline computations of anomalous processes, in synergy with lattice computations and nonet chiral perturbation theory, can uncover novel nonperturbative features of QCD at the Electron-Ion collider.
↳ hep-phhep-lathep-thnucl-thPRD(2025)·15 citations
12
Bayesian Inferring Nucleon's Gravitation Form Factors via Near-threshold $J / ψ$ Photoproduction
Yuxun Guo🇺🇸 · Feng Yuan🇺🇸 · Wenbin Zhao🇺🇸
With Bayesian inference, we investigate the impact of recent near-threshold $J / ψ$ production measurements by the $J / ψ$ 007 experiment and GlueX collaboration on the extraction of proton's gravitational form factors. We apply the generalized parton distribution framework at the next-to-leading order and demonstrate a stable expansion for the near-threshold kinematics. We find that the experimental constraints are in good agreement with the state-of-the-art lattice simulations, where negative $C_{q} (t)$ and $C_{g} (t)$ are strongly preferred. This highlights a great potential to extract them from future high-precision experiments.
↳ hep-phhep-latnucl-thPRL(2025)·32 citations
13
Direct Evidence for the $D ˉ D^{*} / D D ˉ^{*}$ Molecular Nature of $G (3900)$ Through Triangular Singularity Mechanisms
Yin Huang🇨🇳 · Xurong Chen🇨🇳
The exotic hadron $G (3900)$ , initially observed in the process $e^{+} e^{-} \to D D ˉ$ , has been further supported by analyses from the BESIII Collaboration, which classify it as a $P$ -wave molecular state of $D^{+} D^{*-} / D^{-} D^{*+}$ . However, theoretical discussions raise concerns about its status as a true particle, emphasizing the need for additional studies. In this Letter, we employ the triangular singularity mechanism to investigate $G (3900)$ across various reaction channels, allowing us to produce significant peaks without relying on the existence of a real particle. We identify $X (4020)$ , $Y (4320)$ , and the tentative $X (4014)$ as potential sources of these peaks via decay processes to $γ G (3900)$ or $π G (3900)$ . We stress the importance of experimental explorations of $e^{+} e^{-} \to X / Y \to γ (π) G (3900)$ , which are essential for confirming the molecular composition of $D^{+} D^{*-} / D^{-} D^{*+}$ and refining the mass measurement of $G (3900)$ .
↳ hep-phhep-exnucl-th7 citations
14
The Proton Radius Puzzle and Discrepancies in Proton Structure Measurements
Roland B. Lumpay🇺🇸 · Jade C. Jusoy🇺🇸 · Ruel Apas🇺🇸 · Eulogio Auxtero Jr🇺🇸
The proton radius puzzle remains a key challenge in modern physics, highlighting both the precision and limitations of current experimental and theoretical approaches. Recent studies, such as those by Xiong et al. and Bezginov et al., have consistently found a smaller proton radius of about 0.84 femtometers, in line with muonic hydrogen measurements, but discrepancies with earlier electron-proton scattering and atomic hydrogen spectroscopy persist. These unresolved differences reveal systematic errors or limitations in existing theoretical frameworks, as pointed out by Arrington and Sick. The divergence between results from muonic and electronic hydrogen measurements remains unexplained, with contributions from both experimental uncertainties and theoretical gaps. To address these challenges, a coordinated approach is needed-focused on reducing systematic uncertainties through advanced experimental setups, like improved scattering experiments at Jefferson Lab, and developing new theoretical models, such as those proposed by Alarćon et al. and Lin et al. Integrating experimental precision with theoretical rigor offers the best path toward resolving this enduring puzzle and providing deeper insights into the fundamental forces of nature.
↳ nucl-exnucl-th5 citations
15
In-medium bottomonium properties from lattice NRQCD calculations with extended meson operators
H.-T. Ding🇨🇳 · W.-P. Huang🇨🇳 · R. Larsen🇩🇪 · S. Meinel🇺🇸 · Swagato Mukherjee🇺🇸 · P. Petreczky🇺🇸 · Zhanduo Tang🇺🇸
We calculate the temperature dependence of bottomonium correlators in (2+1)-flavor lattice QCD with the aim to constrain in-medium properties of bottomonia at high temperature. The lattice calculations are performed using HISQ action with physical strange quark mass and light quark masses twenty times smaller than the strange quark mass at two lattice spacings $a = 0.0493$ fm and $0.0602$ fm, and temporal extents $N_{τ} = 16 - 30$ , corresponding to the temperatures $T = 133 - 250$ MeV. We use a tadpole-improved NRQCD action including spin-dependent $v^{6}$ corrections for the heavy quarks and extended meson operators in order to be sensitive to in-medium properties of the bottomonium states of interest. We find that within estimated errors the bottomonium masses do not change compared to their vacuum values for all temperatures under our consideration; however, we find different nonzero widths for the various bottomonium states.
↳ hep-lathep-phnucl-thJHEP(2025)·16 citations
16
Chiral condensates and screening masses of neutral pseudoscalar mesons from lattice QCD at physical quark masses
Heng-Tong Ding🇨🇳 · Jin-Biao Gu🇨🇳 · Sheng-Tai Li🇨🇳 · Rishabh Thakkar🇨🇳
We investigate the effects of temperature $T$ and external magnetic fields $e B$ on the chiral condensates and screening masses of neutral pseudoscalar mesons, including $π^{0}$ , $K^{0}$ , and $η_{s s ˉ}^{0}$ , in (2+1)-flavor lattice QCD with physical quark masses. The chiral condensates are intrinsically connected to the screening masses via Ward-Takahashi identities, with the latter characterizing the inverse of the spatial correlation length in the pseudoscalar channel. Using highly improved staggered quarks, we perform simulations on lattices with temporal extents $N_{τ} = 8, 12, 16$ and an aspect ratio of 4, covering five temperatures from 145 MeV to 166 MeV. For each temperature, eight magnetic field strengths are simulated, reaching up to $e B \sim 0.8$ GeV $^{2}$ . These simulations allow us to provide continuum estimates for the chiral condensates and screening masses. We observe intricate behavior in the light ( $u d$ ), strange-light ( $d s$ ) and strange ( $s$ ) quark condensates as functions of the magnetic field and temperature, reflecting the competition between magnetic catalysis and inverse magnetic catalysis effects. This complex behavior is also mirrored in the screening masses of the neutral pseudoscalar mesons. Notably, the screening masses of $π^{0}$ and $K^{0}$ exhibit a non-monotonic dependence on $e B$ , closely following the variations in their corresponding chiral condensates. Meanwhile, the screening mass of $η_{s s ˉ}^{0}$ decreases monotonically with increasing $e B$ . These findings provide valuable insights for understanding the behavior of QCD in a thermomagnetic medium and can serve as benchmarks for low-energy QCD models and effective theories.
↳ hep-lathep-phnucl-thPRD(2025)·18 citations
17
Center vortices and the $SU (3)$ conformal window
J. A. Mickley🇦🇺 · D. B. Leinweber🇦🇺 · D. Nogradi🇭🇺
A novel approach for estimating the lower end of the $SU (3)$ conformal window is presented through the study of center vortex geometry and its dependence on the number of fermion flavors $N_{f}$ . Values ranging from $N_{f} = 2$ -- $8$ are utilized to infer an upper limit for vortex behavior in the low $N_{f}$ phase, which may inform the transition to the conformal window. The simulations are performed at a single lattice spacing and pion mass, both fixed for all $N_{f}$ . Visualizations of the center vortex structure in three-dimensional slices of the lattice reveal a growing roughness in the vortex matter as a function of $N_{f}$ , embodied by an increase in the density of vortex matter in the percolating cluster and a simultaneous reduction in secondary clusters disconnected from the percolating cluster in 3D slices. This is quantified by various bulk properties, including the vortex and branching point densities. A correlation of the vortex structure reveals a turning point near $N_{f} ≃ 5$ past which a randomness in the vortex field becomes the dominant aspect of its evolution with $N_{f}$ . As a byproduct, extrapolations to the vortex content of a uniform-random gauge field provide a critical point at which there must be a drastic shift in vacuum field structure. A precise estimate for the critical value is extracted as $N_{f}^{*} = 11.43 (16) (17)$ , close to various other estimates.
↳ hep-lathep-phhep-thnucl-thPRD(2025)·5 citations
18
Description of femtoscopic correlations with realistic pion-kaon interactions: the $κ / K_{0}^{*} (700)$ case
A. Canoa🇪🇸 · M. Albaladejo🇪🇸 · J. Nieves🇪🇸 · J. R. Peláez🇪🇸 · E. Ruiz Arriola🇪🇸 · J. Ruiz de Elvira🇪🇸
In this work, we show how $π^{+} K_{S}$ femtoscopic correlations, recently reported by ALICE collaboration in $pp$ collisions, can be well described taking into account relativistic corrections and using realistic $π K$ interactions. These are obtained from a dispersive analysis of scattering data, which provides an accurate and model-independent description of the $κ / K_{0}^{*} (700)$ resonance pole. The chiral symmetry suppression of the $π K$ interactions at low energies and the non-ordinary features of the $κ / K_{0}^{*} (700)$ seem to suggest that the $π^{+} K_{S}$ source radius might be surprisingly smaller than for other hadronic processes when using the standard and simple Lednicky-Lyuboshits factorization approximation.
↳ hep-phhep-exnucl-thPoS(2025)·0 citations
19
Dark Matter Effects on the Curvature of Neutron Stars within the new Quarkyonic Model Coupled with Relativistic Mean Field Theory
Jeet Amrit Pattnaik🇮🇳 · D. Dey🇮🇳 · R. N. Panda🇮🇳 · M. Bhuyan🇮🇳 · S. K. Patra🇮🇳
For the first time, we analyze the impact of dark matter (DM) on the curvature properties of quarkyonic neutron stars (NS) using a hybrid model based on quarkyonic-effective field theory within the relativistic mean-field (E-RMF) framework. This study examines the radial variation of curvature components, including the Ricci scalar ( $R$ ), Ricci tensor ( $J$ ), Kretschmann scalar ( $K$ ), and Weyl tensor ( $W$ ), under different DM admixtures. These components offer critical insights into the spacetime geometry and gravitational field strength within the star. The analysis spans canonical mass (1.4 $M_{⊙}$ ) and maximum mass configurations, varying key parameters such as the transition density ( $n_{t}$ ) and QCD confinement scale ( $Λ_{cs}$ ), which influence matter transitions and quark confinement. Our results reveal that DM and quarkyonic matter (QM) significantly affect the star's curvature. Central curvature values, particularly $R$ , $J$ , and $K$ , increase with DM due to higher central densities but decrease with stronger QM effects. Stiffer EOSs yield smoother curvature profiles, while softer EOSs influenced by DM redistribute curvature more dynamically. DM softens the EOS, reducing central pressure and compactness, whereas higher $n_{t}$ values enhance compactness and central pressures. These findings show that dark matter plays a key role in shaping the curvature of quarkyonic neutron stars, offering new insights into compact objects with exotic matter.
↳ astro-ph.HEnucl-th4 citations
20
Evolution of two-neutrons configuration from 11Li to 13Li
P. Andrè · A. Corsi · A. Revel · Y. Kubota · J. Casal · K. Fossez · J. Gomez-Camacho · M. Gomez-Ramos · A. M. Moro · G. Authelet · H. Baba · C. Caesar and 60 other authors
In this work we investigate the two-neutron decay of 13Li and of the excited states of 11Li populated via one-proton removal from 14Be and 12Be, respectively. A phenomenological model is used to describe the decay of 11Li and 13Li. While the first one displays important sequential components, the second one appears dominated by the direct two-neutron decay. A microscopic three-body model is used to extract information on the spatial configuration of the emitted neutrons before the decay and shows that the average distance between the neutrons increases going from 11Li to 13Li.
↳ nucl-exnucl-thPLB(2024)·3 citations
21
Nucleon electric dipole form factor in QCD vacuum
Wei-Yang Liu🇺🇸 · Ismail Zahed🇺🇸
In the QCD vacuum, the nucleon form factors receive contributions from the underlying ensemble of topological pseudoparticles, which are sensitive to a finite vacuum angle $θ$ . We use this observation to derive a novel relationship between the Pauli and electric dipole form factors, for light quark flavors. This relationship allows for an explicit derivation of the proton and neutron electric dipole moments induced by a small CP violating $θ$ angle, in terms of the vacuum topological susceptibity times pertinent magnetic moments. The results compare well with some recent lattice estimates.
↳ hep-phhep-lathep-thnucl-thPRD(2025)·6 citations
22
The role of finite value of strange quark mass $(m_{s} \neq = 0)$ and baryon number density $(n)$ on the stability and maximum mass of strange stars
Pradip Kumar Chattopadhyay🇮🇳 · Debadri Bhattacharjee🇮🇳
This study describes the impact of non-zero value of strange quark mass $(m_{s})$ and number density of baryons $(n)$ on the structure, stability and maximum mass of strange stars. We derive an exact relativistic solution of the Einstein field equation using the Tolman-IV metric potential and modified MIT bag model EoS, $p_{r} = \frac{1}{3} (ρ - 4 B^{'})$ , where $B^{'}$ is a function of bag constant $B$ , $m_{s}$ and baryon number density $(n)$ . Following CERN's findings, transition of phase from hadronic matter to Quark-Gluon Plasma (QGP) may occur at high densities in presence of favourable conditions. The standard MIT bag model, with a constant $B$ , fails to explain such transition properly. Introducing a finite $m_{s}$ and Wood-Saxon parametrisation for $B$ , dependent on baryon number density $(n)$ , provides a more realistic EoS to address such phase transition. Both $m_{s}$ and $n$ constrain the EoS, making it softer as $m_{s}$ increases. Solutions to the TOV equations reveal that for massless strange quarks, maximum mass is 2.01 $M_{⊙}$ and corresponding radius is 10.96 Km when $n = 0.66 f m^{- 3}$ . These values decrease to 1.99 $M_{⊙}$ and 1.96 $M_{⊙}$ , with corresponding radii of 10.88 Km and 10.69 Km for $m_{s} = 50$ and $100 M e V$ respectively having same $n$ value. It is interesting to note that a corelation exists between $n$ and $m_{s}$ . The hadronic to quark matter transition occurs at higher values of $n$ , when $m_{s}$ increases such as $n \geq 0.484, 0.489$ and $0.51 f m^{- 3}$ for $m_{s} = 50$ and $100 M e V$ respectively. Beyond these values, the energy per baryon $(E_{B})$ drops below $930.4 M e V$ , indicating a complete transition to quark matter. For physical analysis, we have considered $n (= 0.578 f m^{- 3})$ which lies in the stable region with $B (n) = 70 M e V / f m^{3}$ . The model provides a viable description of strange stars, satisfying all necessary physical requirements.
↳ gr-qchep-phnucl-thPhys.Dark Univ.(2025)·3 citations
23
Neutron correlations and clustering in neutron-rich nuclear systems
Zaihong Yang · Yuki Kubota
In this paper, we will briefly review the recent progress on neutron correlations and clustering in neutron-rich nuclei from quasi-free scattering experiments. The quasi-free ( $p$ , $p n$ ) reaction was measured for Borromean nuclei $^{11}$ Li, $^{14}$ Be, and $^{17}$ B. A surprisingly small $s$ -wave component was found for $^{17}$ B, revealing a weak neutron halo in $^{17}$ B, and the comparative study of the three nuclei shows the surface localization of dineutron correlation and its universality in Borromean nuclei. The two-neutron emission of $^{16}$ Be was also studied, finding strong dineutron correlation in $^{16}$ Be(g.s.) but weak correlation in $^{16}$ Be( $2^{+}$ ). Two missing-mass measurements using $^{4}$ He( $^{8}$ He, $^{8}$ Be) and $^{8}$ He( $p$ , $p α$ ) reactions provided evidence for the $^{4} n$ resonance, but the $^{3} n$ resonance was not supported by the recent experiment employing the $t (t,^{3}$ He) $^{3} n$ charge-exchange reaction. The quasi-free $(p, p α)$ reaction has been extended to unstable nuclei, and the recent experiment unravels the $α$ - $2 n$ - $α$ molecule-like cluster structure of $^{10}$ Be(g.s.).
↳ nucl-exnucl-thPTEP(2026)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE