Nuclear Theory·nucl-th

Wed·Sep 6, 2023Wednesday·September 6, 2023

26 papers—14 primary·12 cross-listed

01
Entropies, level-density parameters, and fission probabilities along the triaxially- and axially-symmetric fission paths in $^{296}$ Lv
A. Rahmatinejad🇷🇺 · T. M. Shneidman🇷🇺 · G. G. Adamian🇷🇺 · N. V. Antonenko🇷🇺 · P. Jachimowicz🇵🇱 · M. Kowal🇵🇱
We employ a statistical approach to investigate the influence of axial asymmetry on the nuclear level density and entropy along the fission pathways of a superheavy nucleus, explicitly focusing on the $^{296}$ Lv isotope. These pathways are determined within multidimensional deformation spaces. Our analysis reveals a significant impact of triaxiality on entropy. Additionally, suppressing shell effects can alter the fission scenario depending on the available excitation energy. We derive the deformation-dependent level density parameter, which plays a crucial role in estimating the survival probability of a superheavy nucleus. Furthermore, we utilize a set of master equations to obtain the time-dependent fission probabilities and calculate the ratio of decay probabilities for both axial and triaxial paths.
nucl-thEPJA(2024)·7 citations
02
Predication of novel effects in rotational nuclei at high speed
Jian-You Guo🇨🇳
The study of high-speed rotating matter is a crucial research topic in physics due to the emergence of novel phenomena. In this paper, we combined cranking covariant density functional theory (CDFT) with a similar renormalization group approach to decompose the Hamiltonian from the cranking CDFT into different Hermit components, including the non-relativistic term, the dynamical term, the spin-orbit coupling, and the Darwin term. Especially, we obtained the rotational term, the term relating to Zeeman effect-like, and the spin-rotation coupling due to consideration of rotation and spatial component of vector potential. By exploring these operators, we aim to identify novel phenomena that may occur in rotating nuclei. Signature splitting, Zeeman effect-like, spin-rotation coupling, and spin current are among the potential novelties that may arise in rotating nuclei. Additionally, we investigated the observability of these phenomena and their dependence on various factors such as nuclear deformation, rotational angular velocity, and strength of magnetic field.
nucl-thnucl-exquant-phPLB(2024)·2 citations
03
Resolving the $R_{pA}$ and $v_{2}$ puzzle of $D^{0}$ mesons in $p -$ Pb collisions
Chao Zhang🇨🇳 · Zi-Wei Lin🇺🇸 · Liang Zheng🇨🇳 · Shusu Shi🇨🇳
It has been difficult to reconcile the experimental data on the $D^{0}$ meson nuclear modification factor and elliptic flow in $p -$ Pb collisions at LHC energies. Here we study these observables with the string melting version of a multi-phase transport model, which has been improved with the implementation of the Cronin effect (or transverse momentum broadening) and independent fragmentation for charm quarks. Using a strong Cronin effect allows us to provide the first simultaneous description of the $D^{0}$ meson $R_{pA}$ and $v_{2}$ data at $p_{T} \leq$ 8 GeV $/ c$ . The model also provides a reasonable description of the $D^{0}$ meson $p_{T}$ spectra and the low- $p_{T}$ (below $\sim$ 2 GeV $/ c$ ) charged hadron spectra in $p + p$ and $p -$ Pb collisions as well as $R_{pA}$ and $v_{2}$ in $p -$ Pb collisions. We find that both parton scatterings and the Cronin effect are important for the $D^{0}$ meson $R_{pA}$ , while parton scatterings are mostly responsible for the $D^{0}$ meson $v_{2}$ . Our results indicate that it is crucial to include the Cronin effect for the simultaneous description of the $D^{0}$ meson $R_{pA}$ and $v_{2}$ . Since the Cronin effect is expected to grow with the system size, this work implies that the Cronin effect could also be important for heavy hadrons in large systems.
nucl-thhep-phPoS(2024)·4 citations
04
$ΛΛ$ Interaction in a Nuclear Density Functional Theory and Hyperon Puzzle of the Neutron Star
Soonchul Choi🇰🇷 · Emiko Hiyama🇯🇵 · Chang Ho Hyun🇰🇷 · Myung-Ki Cheoun🇰🇷
A Skyrme-type effective potential is determined to describe the interaction between $Λ$ hyperons in nuclear medium. Experimental data of the binding energies of the double- $Λ$ ( $ΛΛ$ ) nuclei with mass numbers $A = 10$ -- $13$ are used to fit the parameters of the $ΛΛ$ interaction. As a result of the fitting, we obtain eight different sets of the $ΛΛ$ interaction parameters, which reproduces the input data within 5\% deviation from the experimental data on average. The eight $ΛΛ$ interactions are plugged in the calculation of the heavier $ΛΛ$ nuclei and the neutron star equation of state to explore the issue of hyperon puzzle. We found that the $ΛΛ$ interaction, specifically, p-wave interaction makes the equation of state stiff enough that the maximum mass of the neutron star can be as large as, or above $2 M_{⊙}$ .
nucl-th3 citations
05
Light clusters in the liquid proto-neutron star inner crust
H. Dinh Thi🇫🇷 · A. F. Fantina🇫🇷 · F. Gulminelli🇫🇷
Being born hot from core-collapse supernova, the crust of the proto-neutron star is expected to be made of a Coulomb liquid and composed of an ensemble of different nuclear species. In this work, we study the beta-equilibrated proto-neutron-star crust in the liquid phase in a self-consistent multi-component approach, employing a compressible liquid-drop description of the ions including the ion centre-of-mass motion. Particular care is also devoted to the calculation of the rearrangement term, thus ensuring thermodynamic consistency. We compare the results of the multi-component plasma calculations with those obtained within a one-component (single-nucleus) approach, showing that important differences arise between the predictions of the two treatments. In particular, the abundances of helium clusters become important using a complete multi-component plasma approach, and eventually dominate the whole distribution at higher temperature in the crust.
nucl-thastro-ph.HEEPJA(2023)·8 citations
06
Ab initio calculation of the alpha-particle monopole transition form factor
Ulf-G. Meißner🇩🇪 · Shihang Shen🇩🇪 · Serdar Elhatisari🇹🇷 · Dean Lee🇺🇸
We present a parameter-free ab initio calculation of the $α$ -particle monopole transition form factor in the framework of nuclear lattice effective field theory. We use a minimal nuclear interaction that was previously used to reproduce the ground state properties of light nuclei, medium-mass nuclei, and neutron matter simultaneously with no more than a few percent error in the energies and charge radii. The results for the monopole transition form factor are in good agreement with recent precision data from Mainz.
nucl-thhep-lathep-phnucl-exPRL(2024)·36 citations
07
Chiral crossover vs chiral density wave in dense nuclear matter
Savvas Pitsinigkos🇬🇧 · Andreas Schmitt🇬🇧
We employ a model based on nucleonic and mesonic degrees of freedom to discuss the competition between isotropic and anisotropic phases in cold and dense matter. Assuming isotropy, the model exhibits a chiral phase transition which is of second order in the chiral limit and becomes a crossover in the case of a realistic pion mass. This observation crucially depends on the presence of the nucleonic vacuum contribution. Allowing for an anisotropic phase in the form of a chiral density wave can disrupt the smooth crossover. We identify the regions in the parameter space of the model where a chiral density wave is energetically preferred. A high-density re-appearance of the chiral density wave with unphysical behavior, as seen in previous studies, is avoided by a suitable renormalization scheme. A nonzero pion mass tends to disfavor the anisotropic phase compared to the chiral limit and we find that, within our model, the chiral density wave is only realized for baryon densities of at least about 6 times nuclear saturation density.
nucl-thhep-phPRD(2024)·9 citations
08
Evolution of Efimov States
Sebastian M. Dawid🇺🇸 · Md Habib E Islam🇺🇸 · Raúl A. Briceño🇺🇸 · Andrew W. Jackura🇺🇸
The Efimov phenomenon manifests itself as an emergent discrete scaling symmetry in the quantum three-body problem. In the unitarity limit, it leads to an infinite tower of three-body bound states with energies forming a geometric sequence. In this work, we study the evolution of these so-called Efimov states using relativistic scattering theory. We identify them as poles of the three-particle $S$ matrix and trace their trajectories in the complex energy plane as they evolve from virtual states through bound states to resonances. We dial the scattering parameters toward the unitarity limit and observe the emergence of the universal scaling of energies and couplings -- a behavior known from the non-relativistic case. Interestingly, we find that Efimov resonances follow unusual, cyclic trajectories accumulating at the three-body threshold and then disappear at some values of the two-body scattering length. We propose a partial resolution to this "missing states" problem.
nucl-thhep-lathep-phphysics.atom-phPRA(2024)·32 citations
09
Thermodynamics of an updated hadronic resonance list and influence on hadronic transport
Jordi Salinas San Martín🇺🇸 · Renan Hirayama🇩🇪 · Jan Hammelmann🇩🇪 · Jamie M. Karthein🇺🇸 · Paolo Parotto🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸 · Claudia Ratti🇺🇸 · Hannah Elfner🇩🇪
Hadron lists based on experimental studies summarized by the Particle Data Group (PDG) are a crucial input for the equation of state and thermal models used in the study of strongly-interacting matter produced in heavy-ion collisions. Modeling of these strongly-interacting systems is carried out via hydrodynamical simulations, which are followed by hadronic transport codes that also require a hadronic list as input. To remain consistent throughout the different stages of modeling of a heavy-ion collision, the same hadron list with its corresponding decays must be used at each step. It has been shown that even the most uncertain states listed in the PDG from 2016 are required to reproduce partial pressures and susceptibilities from Lattice Quantum Chromodynamics with the hadronic list known as the PDG2016+. Here, we update the hadronic list for use in heavy-ion collision modeling by including the latest experimental information for all states listed in the Particle Data Booklet in 2021. We then compare our new list, called PDG2021+, to Lattice Quantum Chromodynamics results and find that it achieves even better agreement with the first principles calculations than the PDG2016+ list. Furthermore, we develop a novel scheme based on intermediate decay channels that allows for only binary decays, such that PDG2021+ will be compatible with the hadronic transport framework SMASH. Finally, we use these results to make comparisons to experimental data and discuss the impact on particle yields and spectra.
nucl-thhep-phnucl-ex27 citations
10
Far-from-equilibrium bulk-viscous transport coefficients in neutron star mergers
Yumu Yang🇺🇸 · Mauricio Hippert🇺🇸 · Enrico Speranza🇺🇸 · Jorge Noronha🇺🇸
We investigate the weak-interaction-driven bulk-viscous transport properties of $n p e$ matter in the neutrino transparent regime. Previous works assumed that the induced bulk viscosity correction to pressure, near beta equilibrium, is linear in deviations from the equilibrium charge fraction. We show that this is not always true for (some) realistic equations of state at densities between one and three times saturation density. This nonlinear nature of the perturbation around equilibrium motivates a far-from-beta-equilibrium description of bulk-viscous transport in neutron star mergers, which can be precisely achieved using a new Israel-Stewart formulation with resummed bulk and relaxation time transport coefficients. The computation of these transport coefficients depends on out-of-beta-equilibrium pressure corrections, which can be computed for a given equation of state. We calculate these coefficients for equations of state that satisfy the latest constraints from multi-messenger observations from LIGO/VIRGO and NICER. We show that varying the nuclear symmetry energy $J$ and its slope $L$ can significantly affect the transport coefficients and the nonlinear behavior of the out-of-equilibrium pressure corrections. Therefore, having better constraints on $J$ and $L$ will directly impact our understanding of bulk-viscous processes in neutron star mergers.
nucl-thastro-ph.HEhep-phPRC(2024)·40 citations
11
Clustering effects in the $^{6}$ Li(p, $^{3}$ He) $^{4}$ He reaction at astrophysical energies
Salvatore Simone Perrotta · Maria Colonna🇮🇹 · José Antonio Lay🇪🇸
Background: The understanding of nuclear reactions between light nuclei at energies below the Coulomb barrier is important for several astrophysical processes, but their study poses experimental and theoretical challenges. At sufficiently low energies, the electrons surrounding the interacting ions affect the scattering process. Moreover, the clustered structure of some of these nuclei may play a relevant role on the reaction observables. Purpose: In this article, we focus on a theoretical investigation of the role of clustered configurations of $^{6}$ Li in reactions of astrophysical interest. Methods: The $^{6}$ Li(p, $^{3}$ He) $^{4}$ He reaction cross section is described considering both the direct transfer of a deuteron as a single point-like particle in Distorted Wave Born Approximation (DWBA), and the transfer of a neutron and a proton in second-order DWBA. A number of two- and three-cluster structure models for $^{6}$ Li are compared. Results: Within the two-cluster structure model, we explore the impact of the deformed components in the $^{6}$ Li wave-function on the reaction of interest. Within the three-cluster structure model, we gauge the degree of $α$ -d clustering and explicitly probe its role on specific features of the reaction cross section. We compare the energy trend of the astrophysical $S$ factor deduced in each case. Conclusions: Clustered $^{6}$ Li configurations lead in general to a significant enhancement of the astrophysical factor in the energy region under study. This effect only originates from clustering, whereas static deformations of the ground-state configuration play a negligible role at very low energies.
nucl-th0 citations
12
Microscopic investigation of one- and two-proton decay from the excited states of 10C
Qing Zhao🇨🇳 · Masaaki Kimura🇯🇵 · Bo Zhou🇨🇳 · Seung-heon Shin🇲🇦
We present microscopic cluster model calculations for the 1p and 2p decays of the 0+2 and 2+2 states of 10C. With the R-matrix method, we have estimated the decay widths. The obtained 1p and 2p decay widths are in good agreement with the recent experimental data and support the validity of the di-proton approximation for the 2p decay of 10C(0+2). We also show the suppression of the 1p decay of the 10C(0+2) state due to the structure mismatch with the decay channel.
nucl-thPLB(2024)·6 citations
13
The role of three-nucleon potentials within the shell model: past and present
L. Coraggio🇮🇹 · G. De Gregorio🇮🇹 · T. Fukui🇯🇵 · A. Gargano🇮🇹 · Y. Z. Ma🇺🇸 · Z. H. Cheng🇨🇳 · F. R. Xu🇨🇳
We survey the impact of nuclear three-body forces on structure properties of nuclei within the shell model. It has long been acknowledged, since the seminal works of Zuker and coworkers, that three-body forces play a fundamental role in making the monopole component of shell-model Hamiltonians, derived from realistic nucleon-nucleon potentials, able to reproduce the observed evolution of the shell structure. In the vast majority of calculations, however, their effects have been taken into account by shell-model practitioners by introducing ad hoc modifications of the monopole matrix elements. During last twenty years, a new theoretical approach, framed within the chiral perturbation theory, has progressed in developing nuclear potentials, where two- and many-body components are naturally and consistently built in. This new class of nuclear forces allows to carry out nuclear structure studies that are improving our ability to understand nuclear phenomena in a microscopic approach. We provide in this work an update on the status of the nuclear shell model based on realistic Hamiltonians that are derived from two- and three-nucleon chiral potentials, focusing on the role of the three-body component to provide the observed shell evolution and closure properties, as well as the location of driplines. To this end, we present the results of shell-model calculations and their comparison with recent experimental measurements, which enlighten the relevance of the inclusion of three-nucleon forces to master our knowledge of the physics of atomic nuclei.
nucl-thPPNP(2024)·18 citations
14
Neural Network Solutions of Bosonic Quantum Systems in One Dimension
Paulo F. Bedaque🇺🇸 · Hersh Kumar🇺🇸 · Andy Sheng🇺🇸
Neural networks have been proposed as efficient numerical wavefunction ansatze which can be used to variationally search a wide range of functional forms for ground state solutions. These neural network methods are also advantageous in that more variational parameters and system degrees of freedom can be easily added. We benchmark the methodology by using neural networks to study several different integrable bosonic quantum systems in one dimension and compare our results to the exact solutions. While testing the scalability of the procedure to systems with many particles, we also introduce using symmetric function inputs to the neural network to enforce exchange symmetries of indistinguishable particles.
nucl-thcond-mat.dis-nncond-mat.quant-gasquant-phPRC(2024)·7 citations
15
Upper Limit on the Chiral Magnetic Effect in Isobar Collisions at the Relativistic Heavy-Ion Collider
STAR Collaboration: M. I. Abdulhamid · B. E. Aboona · J. Adam · J. R. Adams · G. Agakishiev · I. Aggarwal · M. M. Aggarwal · Z. Ahammed · A. Aitbaev · I. Alekseev · E. Alpatov · A. Aparin and 345 other authors
The chiral magnetic effect (CME) is a phenomenon that arises from the QCD anomaly in the presence of an external magnetic field. The experimental search for its evidence has been one of the key goals of the physics program of the Relativistic Heavy-Ion Collider. The STAR collaboration has previously presented the results of a blind analysis of isobar collisions ( $_{44}^{96} Ru +_{44}^{96} Ru$ , $_{40}^{96} Zr +_{40}^{96} Zr$ ) in the search for the CME. The isobar ratio ( $Y$ ) of CME-sensitive observable, charge separation scaled by elliptic anisotropy, is close to but systematically larger than the inverse multiplicity ratio, the naive background baseline. This indicates the potential existence of a CME signal and the presence of remaining nonflow background due to two- and three-particle correlations, which are different between the isobars. In this post-blind analysis, we estimate the contributions from those nonflow correlations as a background baseline to $Y$ , utilizing the isobar data as well as Heavy Ion Jet Interaction Generator simulations. This baseline is found consistent with the isobar ratio measurement, and an upper limit of 10% at 95% confidence level is extracted for the CME fraction in the charge separation measurement in isobar collisions at $s_{NN} = 200$ GeV.
↳ nucl-exnucl-thPRResearch(2024)·28 citations
16
Jet quenching in anisotropic flowing matter
Matvey V. Kuzmin🇷🇺 · Xoán Mayo López🇪🇸 · Jared Reiten🇺🇸 · Andrey V. Sadofyev🇪🇸
We study the interplay between the flow and hydrodynamic gradients in jet quenching at first order in opacity. We find that the mixed flow-gradient contributions in jet quenching are enhanced by the medium length, and survive in the eikonal limit, dominating over other medium evolution effects. The resulting modification to the jet quenching parameter and energy loss rate can be substantial, leading to ample phenomenological implications. We also compute the leading corrections to the jet broadening due to the flow velocity gradients, and consider the leading gradient effects in the medium-induced branching for general kinematics, extending the recent considerations of jets in inhomogeneous media. These results can be straightforwardly coupled to matter simulations, providing new opportunities for jet tomography in heavy-ion collisions.
↳ hep-phnucl-thPRD(2024)·44 citations
17
Side Ridge in Ar + KCl Collisions at 1.8 GeV/nucleon with Reaction-Plane Deblurring
Pawel Danielewicz🇺🇸 · Herbert Stroebele · Pierre Nzabahimana
Reaction-plane deblurring is applied to the triple-differential distributions of protons, deuterons and negatively charged pions from central Ar + KCl collisions at 1.8 GeV/nucleon, measured with the LBL-GSI Streamer Chamber, to yield distributions relative to the true reaction plane of the collisions. Within the reaction plane and in the forward cm rapidity region a side ridge away from the beam axis is observed: the distributions peak away from the beam direction for protons and deuterons but not for pions. These findings are consistent with a source of particles moving at an in-plane transverse velocity of ~0.1 c. Transport pBUU calculations yield results in semi-quantitative agreement with those from the data.
↳ nucl-exnucl-thPRC(2023)·3 citations
18
Electrical conductivity of warm neutron star crust in magnetic fields: Neutron-drip regime
Arus Harutyunyan🇦🇲 · Armen Sedrakian🇩🇪 · Narine T. Gevorgyan · Mekhak V. Hayrapetyan
We compute the anisotropic electrical conductivity tensor of the inner crust of a compact star at non-zero temperature by extending a previous work on the conductivity of the outer crust. The physical scenarios, where such crust is formed, involve proto-neutron stars born in supernova explosions, binary neutron star mergers and accreting neutron stars. The temperature-density range studied covers the transition from a non-degenerate to a highly degenerate electron gas and assumes that the nuclei form a liquid, i.e., the temperature is above the melting temperature of the lattice of nuclei. The electronic transition probabilities include (a) the dynamical screening of electron-ion interaction in the hard-thermal-loop approximation for the QED plasma, (b) the correlations of the ionic component in a one-component plasma, and (c) finite nuclear size effects. The conductivity tensor is obtained from the Boltzmann kinetic equation in relaxation time approximation accounting for the anisotropies introduced by a magnetic field. The sensitivity of the results towards the matter composition of the inner crust is explored by using several compositions of the inner crust which were obtained using different nuclear interactions and methods of solving the many-body problem. The standard deviation of relaxation time and components of the conductivity tensor from the average are below $\leq 10%$ except close to crust-core transition, where non-spherical nuclear structures are expected. Our results can be used in dissipative magneto-hydrodynamics (MHD) simulations of warm compact stars.
↳ astro-ph.HEastro-ph.SRnucl-thPRC(2024)·10 citations
19
The proto-neutron star inner crust in a multi-component plasma approach
H. Dinh Thi🇫🇷 · A. F. Fantina🇫🇷 · F. Gulminelli🇫🇷
Proto-neutron stars (PNS) are born hot, with temperatures exceeding a few times $1 0^{10}$ K. In these conditions, the PNS crust is expected to be made of a Coulomb liquid composed of an ensemble of different nuclear species. We perform a study of the beta-equilibrated PNS crust in the liquid phase in a self-consistent multi-component plasma (MCP) approach, thus allowing us to consistently calculate the impurity parameter, often taken as a free parameter in cooling simulations. We developed a self-consistent MCP approach at finite temperature using a compressible liquid-drop description of the ions, with surface parameters adjusted to reproduce experimental masses. The treatment of the ion centre-of-mass motion was included through a translational free-energy term accounting for in-medium effects. The results of self-consistent MCP calculations are systematically compared with those performed in a perturbative and in the one-component plasma treatment. We show that the inclusion of non-linear mixing terms arising from the ion centre-of-mass motion leads to a breakdown of the ensemble equivalence between the one-component and MCP approach. Our findings illustrate that the abundance of light nuclei becomes important, eventually dominating the distribution at higher density and temperature. This is reflected in the impurity parameter, which, in turn, may have a potential impact on NS cooling. For practical applications, we also provide a fitting formula for the impurity parameter in the PNS inner crust. Our results obtained within a self-consistent MCP approach show important differences in the prediction of the PNS composition with respect to those obtained with a one-component or a perturbative MCP approximation, particularly in the deeper region of the crust. This highlights the importance of a full, self-consistent MCP calculation for reliable predictions of the PNS crust composition.
↳ astro-ph.HEnucl-thAstron.Astrophys.(2023)·11 citations
20
Unified equations of state for cold non-accreting neutron stars with Brussels-Montreal functionals. IV. Role of the symmetry energy in pasta phases
N. N. Shchechilin🇧🇪 · N. Chamel🇧🇪 · J. M. Pearson
Our previous investigation of neutron-star crusts, based on the functional BSk24, led to a substantial reduction of the pasta mantle when Strutinsky integral and pairing corrections were added on top of the fourth-order extended Thomas-Fermi method (ETF). Here, our earlier calculations are widened to a larger set of functionals within the same family, and we find that the microscopic corrections weaken significantly the influence of the symmetry energy. In particular, the correlation observed at the pure ETF level between the density for the onset of pasta formation and the symmetry energy vanishes, not only for the $L$ coefficient but also for the symmetry-energy values at the relevant densities. Moreover, the inclusion of microscopic corrections results in a much lower abundance of pasta for all functionals.
↳ astro-ph.HEnucl-thPRC(2023)·21 citations
21
Nuclear charge radii of silicon isotopes
Kristian König🇩🇪 · Julian C. Berengut🇦🇺 · Anastasia Borschevsky🇳🇱 · Alex Brinson🇺🇸 · B. Alex Brown🇺🇸 · Adam Dockery🇺🇸 · Serdar Elhatisari🇹🇷 · Ephraim Eliav🇮🇱 · Ronald F. Garcia Ruiz🇺🇸 · Jason D. Holt🇨🇦 · Bai-Shan Hu🇨🇦 · Jonas Karthein🇺🇸 and 11 other authors
The nuclear charge radius of $^{32}$ Si was determined using collinear laser spectroscopy. The experimental result was confronted with ab initio nuclear lattice effective field theory, valence-space in-medium similarity renormalization group, and mean field calculations, highlighting important achievements and challenges of modern many-body methods. The charge radius of $^{32}$ Si completes the radii of the mirror pair $^{32}$ Ar - $^{32}$ Si, whose difference was correlated to the slope $L$ of the symmetry energy in the nuclear equation of state. Our result suggests $L \leq 60$ \,MeV, which agrees with complementary observables.
↳ nucl-exnucl-thPRL(2024)·52 citations
22
Hadronization dynamics from the spectral representation of the gauge invariant quark propagator
Caroline S. R. Costa🇺🇸 · Alberto Accardi🇺🇸 · Andrea Signori🇮🇹
Using the spectral representation of the quark propagator we study the Dirac decomposition of the gauge invariant quark propagator, whose imaginary part describes the hadronization of a quark as this interacts with the vacuum. We then demonstrate the formal gauge invariance of the so-called jet mass, that is of the coefficient of the chiral-odd part of the gauge invariant propagator, that can be expressed in any gauge as the first moment of the chiral-odd quark spectral function. This is therefore revealed to be a \textit{bona fide} QCD observable encoding aspects of the dynamical mass generation in the QCD vacuum, and is furthermore experimentally measurable in specific twist-3 longitudinal-transverse asymmetries in DIS and in semi-inclusive electron-positron collisions. In light-like axial gauges, we also obtain a new sum rule for the spectral function associated with the gauge fixing vector. We finally present a gauge-dependent formula that connects the second moment of the chiral-even coefficient of the quark spectral function to invariant mass generation and final state rescattering in the hadronization of a quark. Finding twist-4 experimental observables sensitive to this quantity is left for future work.
↳ hep-phnucl-th0 citations
23
Acceleration of a polarized neutron by internal weak nuclear forces
M. Donaire🇪🇸
It is proven that a polarized neutron gets accelerated by internal nuclear forces along the coherent rotation of its spin. The net force upon the neutron arises from the weak nuclear interactions between its quarks. It is the result of the simultaneous breaking of parity symmetry by the chiral interactions between the neutron's quarks, and of time-reversal symmetry along the inversion of their spins. The variation of the neutron's kinetic momentum is accompanied with the transfer of an equivalent momentum to the fields of the Z and W bosons that mediate the interactions, in the opposite direction. The effect is linear in Fermi's constant. Using the simplest hadron models, an upper bound of the order of meters per second is estimated for the velocity variation of the polarized neutron along the spin-flip process.
↳ hep-phnucl-th1 citation
24
Nontrivial features in the speed of sound inside neutron stars
Debora Mroczek🇺🇸 · M. Coleman Miller🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸 · Nicolas Yunes🇺🇸
Measurements of neutron star masses, radii, and tidal deformability have direct connections to nuclear physics via the equation of state (EoS), which for the cold, catalyzed matter in neutron star cores is commonly represented as the pressure as a function of energy density. Microscopic models with exotic degrees of freedom display nontrivial structure in the speed of sound ( $c_{s}$ ) in the form of first-order phase transitions and bumps, oscillations, and plateaus in the case of crossovers and higher-order phase transitions. We present a procedure based on Gaussian processes to generate an ensemble of EoSs that include nontrivial features. Using a Bayesian analysis incorporating measurements from X-ray sources, gravitational wave observations, and perturbative QCD results, we show that these features are compatible with current constraints. We investigate the possibility of a global maximum in $c_{s}$ that occurs within the densities realized in neutron stars -- implying a softening of the EoS and possibly an exotic phase in the core of massive stars -- and find that such a global maximum is consistent with, but not required by, current constraints.
↳ astro-ph.HEgr-qcnucl-thPRD(2024)·77 citations
25
Implications of correlations and fluctuations in small systems
Debasish Das🇮🇳
The small collision systems like p+p and p+A collisions have shown new features like A+A collisions in the relativistic regime. These new aspects in small systems which have altered our research and understanding on the two-particle correlation measurements have been provided. Additionally, a critical observation of the fluctuation measurements provides new ways to infer such novel happening in the small collision systems. The ongoing and future endeavors towards the new measurements are also discussed.
↳ nucl-exhep-exhep-phnucl-thInt.J.Mod.Phys.A(2022)·1 citation
26
SU(3) parity doubling in cold neutron star matter
Eduardo S. Fraga🇧🇷 · Rodrigo da Mata🇧🇷 · Jürgen Schaffner-Bielich🇩🇪
We present a phenomenological model to investigate the chiral phase transition characterized by parity doubling in dense, beta equilibrated, cold matter. Our model incorporates effective interactions constrained by SU(3) relations and considers baryonic degrees of freedom. By constraining the model with astrophysical data and nuclear matter properties, we find a first-order phase transition within realistic values of the slope parameter L. The inclusion of the baryon octet and negative parity partners, along with a chiral-invariant mass $m_{0}$ , allows for a non-massless chiral symmetric phase. Through exploration of parameter space, we identify parameter sets satisfying mass and radius constraints without requiring a partonic phase. The appearance of the parity partner of the nucleon, the N(1535) resonance, suppresses strangeness, pushing hyperonization to higher densities. We observe a mild first-order phase transition to the chirally restored phase, governed by $m_{0}$ . Our calculations of surface tension highlight its strong dependence on $m_{0}$ . The existence of mixed phases is ruled out since they become energetically too costly. We compare stars with metastable and stable cores using both branches of the equation of state. Despite limited lifespans due to low surface tension values, phase conversion and star contraction could impact neutron stars with masses around 1.3 solar masses or more. We discuss some applications of this model in its non-zero temperatures generalization and scenarios beyond beta equilibrium that can provide insights into core-collapse supernovae, proto-neutron star evolution, and neutron star mergers. Core-collapse supernovae dynamics, influenced by chiral symmetry restoration and exotic hadronic states, affect explosion mechanisms and nucleosynthesis.
↳ hep-phastro-ph.HEnucl-thPRD(2023)·19 citations

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