Nuclear Theory·nucl-th

Wednesday·June 22, 2022

24 papers—15 primary·9 cross-listed

01
Magnetic quadrupole transitions in the relativistic energy density functional theory
G. Kružić · T. Oishi · N. Paar
Background: Magnetic quadrupole (M2) excitation represents a fundamental feature in atomic nucleus associated to nuclear magnetism induced by spin and orbital transition operator. So far it has only been investigated within the non-relativistic theoretical approaches, and available experimental data are rather limited. Purpose: We aim to investigate the properties of M2 transitions in closed and open-shell nuclei using the framework of relativistic nuclear energy density functional. The calculated M2 transition strengths could be used to constrain the quenching of the spin gyromagnetic factors. Methods: The M2 excitations are described using the relativistic quasiparticle random phase approximation (RQRPA) with the residual interaction extended with the isovector-pseudovector term. Results: The M2 transition strength distributions are described and analyzed for closed and open shell nuclei. The results are compared with available experimental data and the strength missing from the experiment is discussed. The evolution of M2 transition properties has been investigated within the $^{36 - 64} Ca$ isotope chain. Conclusion: The main M2 transitions have rather rich underlying structure and their collectivity increases with the mass number due to larger number of contributing particle-hole configurations. Pairing correlations in open shell nuclei have strong effect, causing the M2 strength reduction and shifting of the centroid energies to higher values. The analysis of M2 transition strengths indicate that considerable amount of experimental strength may be missing, mainly due to limitations to rather restricted energy ranges. The calculated M2 strengths for Ca isotopes, together with the future experimental data will allow constraining the quenching of the $g$ factors in nuclear medium.
nucl-thnucl-exEPJA(2023)·6 citations
02
First extraction of the proton mass radius and scattering length $α_{ρ^{0} p}$ from $ρ^{0}$ photoproduction
Xiao-Yun Wang🇨🇳 · Fancong Zeng🇨🇳 · Quanjin Wang🇨🇳 · Li Zhang🇨🇳
As it involves the lightest physical states excited from the vacuum by the vector quark current, near-threshold $ρ^{0}$ photoproduction is considered a possible way to research the proton radius and the absolute value of the scattering lengths of the $ρ^{0}$ --proton interaction. In this work, under the assumption of a scalar form factor of dipole form, the value of the proton mass radius is calculated as $0.85 \pm 0.06 fm$ by fitting the differential cross section of the $γ p \to ρ^{0} p$ reaction at near-threshold energy. For light vector meson photoproduction, because the exchange of a scalar quark--antiquark pair is not suppressed and should dominate the scalar gluon exchange, the radius we extract from $ρ^{0}$ photoproduction is likely to represent the quark radius of the proton. This fact may explain why the value obtained in this work is very near the proton charge radius. Moreover, the absolute value of the $ρ^{0}$ --proton scattering length $∣ α_{ρ^{0} p} ∣ = 0.31 \pm 0.06 fm$ is obtained for the first time within the vector meson dominance model. This result disobeys the rule that the absolute value of the vector meson and proton scattering length $∣ α_{V p} ∣$ increases with the meson's mass, which can be attributed to treating the $ρ^{0}$ meson as a point in the analysis. These results provide useful theoretical information for an in-depth understanding of proton structure and the proton--vector meson interaction.
nucl-thSCPMA(2023)·19 citations
03
Strange quark matter from a baryonic approach
Eduardo S. Fraga🇧🇷 · Rodrigo da Mata🇧🇷 · Savvas Pitsinigkos🇬🇧 · Andreas Schmitt🇬🇧
We construct a model for dense matter based on low-density nuclear matter properties that exhibits a chiral phase transition and that includes strangeness through hyperonic degrees of freedom. Empirical constraints from nuclear matter alone allow for various scenarios, from a strong first-order chiral transition at relatively low densities through a weaker transition at higher densities, even up to a smooth crossover not far beyond the edge of the allowed range. The model parameters can be chosen such that at asymptotically large densities the chirally restored phase contains strangeness and the speed of sound approaches the conformal limit, resulting in a high-density phase that resembles deconfined quark matter. Additionally, if the model is required to reproduce sufficiently massive compact stars, the allowed parameter range is significantly narrowed down, resulting for instance in a very narrow range for the poorly known slope parameter of the symmetry energy, $L ≃ (88 - 92) MeV$ . We also find that for the allowed parameter range strangeness does not appear in the form of hyperons in the chirally broken phase and the chiral transition is of first order. Due to its unified approach and relative simplicity - here we restrict ourselves to zero temperature and the mean-field approximation - the model can be used in the future to study dense matter under compact star conditions in the vicinity of the chiral phase transition, for instance to compute the surface tension or to investigate spatially inhomogeneous phases.
nucl-thastro-ph.HEhep-phPRD(2022)·15 citations
04
Longitudinal and Transverse form Factors from $^{65}$ Cu and $^{71}$ Ga Nuclei
Sarah M. Obaid · Fouad A. Majeed
In the present work, the inelastic electron scattering for longitudinal and transverse form factors of $^{65}$ Cu and $^{71}$ Ga nuclei lie in the fp-shell region are studied in the framework of the shell model. The calculation is performed in the ( $1 f_{5/2}$ , $2 p_{3/2}$ , $2 p_{1/2}$ , $1 g_{9/2}$ ) model space using jun45 effective interaction. The wavefunctions employed to conduct the shell model calculations are extracted from the jun45 effective interaction for these nuclei with the jj44 shell model space and $(S k 35 - S k z s^{*})$ residual interaction to evaluate the interactions matrix element between initial and final states. The effective charges used to account for the core-polarization (CP) effect are created using calculations of microscopic perturbations that include intermediate one-particle, one-hole excitation from the core and the model space (MS) orbits into all upper orbits with n $ℏ ω$ excitations following the same approach done in [Ref.20]. To account for the (CP) effects contribution, the inelastic form factor is obtained by employing the shape of Tassie and Bohr-Mottelson models with appropriate proton and neutron effective charges. The calculated form factors were compared with available experimental data.
nucl-thJ.Korean Phys.Soc.(2023)·0 citations
05
Robust ab initio prediction of nuclear electric quadrupole observables by scaling to the charge radius
Mark A. Caprio · Patrick J. Fasano · Pieter Maris
Meaningful predictions for electric quadrupole (E2) observables from ab initio nuclear theory are necessary, if the ab initio description of collective correlations is to be confronted with experiment, as well as to provide predictive power for unknown E2 observables. However, converged results for E2 observables are notoriously challenging to obtain in ab initio no-core configuration interaction (NCCI) approaches. Matrix elements of the E2 operator are sensitive to the large-distance tails of the nuclear wave function, which converge slowly in an oscillator basis expansion. Similar convergence challenges beset ab initio prediction of the nuclear charge radius. We demonstrate that the convergence patterns of the E2 and radius observables are strongly correlated, and that meaningful predictions for the absolute scale of E2 observables may be made by calibrating to the experimentally-known ground-state charge radius. We illustrate by providing robust ab initio predictions for several E2 transition strengths and quadrupole moments in p-shell nuclei, in cases where experimental results are available for comparison.
nucl-thPRC(2022)·29 citations
06
Nuclear pasta structures at high temperatures
Cheng-Jun Xia · Toshiki Maruyama · Nobutoshi Yasutake · Toshitaka Tatsumi
We investigate nuclear pasta structures at high temperatures in the framework of relativistic mean field model with Thomas-Fermi approximation. Typical pasta structures (droplet, rod, slab, tube, and bubble) are obtained, which form various crystalline configurations. The properties of those nuclear pastas are examined in a three-dimensional geometry with reflection symmetry, where the optimum lattice constants are fixed by reproducing the droplet/bubble density that minimizes the free energy adopting spherical or cylindrical approximations for Wigner-Seitz cells. It is found that different crystalline structures can evolve into each other via volume conserving deformations. For fixed densities and temperatures, the differences of the free energies per baryon of nuclear pasta in various shapes and lattice structures are typically on the order of tens of keV, suggesting the possible coexistence of those structures. As temperature increases, the thermodynamic fluctuations are expected to disrupt the long-range ordering in nuclear pasta structures. We then estimate the critical conditions for nuclear pasta to become disordered and behave like liquid, which are found to be sensitive to the densities, temperatures, proton fractions, and nuclear shapes. If we further increase temperature, eventually the nonuniform structures of nuclear pasta become unstable and are converted into uniform nuclear matter. The phase diagrams of nuclear matter are then estimated, which should be useful for understanding the evolutions of neutron stars, supernova dynamics, and binary neutron star mergers.
nucl-thastro-ph.HEPRD(2022)·15 citations
07
Lattice Monte Carlo Simulations with Two Impurity Worldlines
Fabian Hildenbrand🇩🇪 · Serdar Elhatisari🇹🇷 · Timo A. Lähde🇩🇪 · Dean Lee🇺🇸 · Ulf-G. Meißner🇩🇪
We develop the impurity lattice Monte Carlo formalism, for the case of two distinguishable impurities in a bath of polarized fermions. The majority particles are treated as explicit degrees of freedom, while the impurities are described by worldlines. The latter serve as localized auxiliary fields, which affect the majority particles. We apply the method to non-relativistic three-dimensional systems of two impurities and a number of majority particles where both the impurity-impurity interaction and the impurity-majority interaction have zero range. We consider the case of an attractive impurity-majority interaction, and we study the formation and disintegration of bound states as a function of the impurity-impurity interaction strength. We also discuss the potential applications of this formalism to other quantum many-body systems.
nucl-thhep-lathep-phphysics.comp-phEPJA(2022)·10 citations
08
On the separability of microscopic optical model potentials and emerging bell-shape Perey-Buck nonlocality
H. F. Arellano🇨🇱 · G. Blanchon🇫🇷
After nearly sixty years since its introduction, the phenomenological bell-shape Perey-Buck spatial nonlocality in the optical model potential for nucleon-nucleus scattering has remained unaccounted for from a microscopic standpoint. In this article we provide a quantitative account for such nonlocality considering fully nonlocal optical potentials in momentum space. The framework is based on a momentum-space in-medium folding model, where infinite nuclear matter $g$ matrices in Brueckner-Hartree-Fock approximation are folded to the target one-body mixed density. The study is based on chiral next-to-next-to-next-to-leading order (N3LO) as well as Argonne $v_{18}$ nucleon-nucleon bare interaction models. Applications focus on $^{40}$ Ca( $p, p$ ) scattering at beam energies in the range 11-200 MeV, resulting in the identification of a separable structure of the momentum-space optical potential of a form we coin as $J v H$ , with a nonlocality form factor as one of its terms. The resulting nonlocaliy form factor features a bell-shape with nonlocality range $β$ between 0.86 and 0.89 fm, for both proton and neutron beams at energies below 65 MeV. An analytic toy model is introduced to elucidate the underlying mechanism for the nonlocality in the optical model, providing an estimate of its range based on the Fermi motion of the target nucleons and the long-range part of the $N N$ interaction.
nucl-thEPJA(2022)·12 citations
09
Importance of the deuteron breakup in the deuteron knockout reaction
Yoshiki Chazono · Kazuki Yoshida · Kazuyuki Ogata
An isoscalar $p n$ pair is expected to emerge in nuclei that have similar proton and neutron numbers and it may be a candidate for a deuteron ``cluster.'' There is, however, no experimental evidence for it. The purpose of this paper is to construct a new reaction model for the ( $p, p d$ ) reaction including the deuteron breakup in the elementary process and the deuteron reformation by the final-state interactions (FSIs). How these processes contribute to the observables of the reaction is investigated. The distorted wave impulse approximation is extended in twofold. The elementary processes of the ( $p, p d$ ), i.e., the $p$ - $d$ elastic scattering and $d (p, p) p n$ reaction, are described with an impulse picture employing a nucleon-nucleon effective interaction. The three-body scattering waves in the final state of the ( $p, p d$ ) reaction are calculated with the continuum-discretized coupled-channels method. The triple differential cross section (TDX) of the ( $p, p d$ ) reaction is calculated with the new model. The elementary processes are described reasonably well with the present model. As for the ( $p, p d$ ) reaction, the deuteron reformation can either increase or decrease the TDX height depending on the interference between the elastic and breakup channel of deuteron, while the \textit{back-coupling} effect always decreases it. It is shown that the deuteron reformation significantly changes the TDX of the ( $p, p d$ ) reaction through the interference. It is important to include this process to quantitatively discuss the ( $p, p d$ ) cross sections in view of the deuteron formation in nuclei. For more quantitative discussion regarding the experimental data, further improvement will be necessary.
nucl-thPRC(2022)·12 citations
10
Green's Function Knockout Formalism
Chloë Hebborn · Gregory Potel
Knockout nuclear reactions, in which a nucleon is removed from a nucleus as a result of the collision with another nucleus, have been widely used as an experimental tool, both to populate isotopes further removed from stability, and to obtain information about the single-particle nature of the nuclear spectrum. In order to fully exploit the experimental information, theory is needed for the description of both the structure of the nuclei involved, and the dynamics associated with the nucleon removal mechanisms. The standard approach, using theoretical shell-model spectroscopic factors for the structure description coupled with an eikonal model of reaction, has been successful when used in the context of the removal of valence nucleons in nuclei close to stability. However, it has been argued that the reaction theory might need to be revisited in the case of exotic nuclei, more specifically for highly asymmetric nuclei in which the deficient species (neutrons or protons) is being removed. We present here a new formalism for the nucleon-removal and -addition reaction through knockout and transfer reactions, that treats consistently structure and reaction properties using dispersive optical potentials. In particular, our formalism includes the dynamical effects associated with the removal of a neutron from the projectile, which might explain the long standing puzzle of the quenching of spectroscopic factors in nuclei with extreme neutrons-to-protons ratios.
nucl-thPRC(2023)·10 citations
11
Hidden-nucleons neural-network quantum states for the nuclear many-body problem
A. Lovato🇺🇸 · C. Adams🇺🇸 · G. Carleo🇨🇭 · N. Rocco🇺🇸
We generalize the hidden-fermion family of neural network quantum states to encompass both continuous and discrete degrees of freedom and solve the nuclear many-body Schrödinger equation in a systematically improvable fashion. We demonstrate that adding hidden nucleons to the original Hilbert space considerably augments the expressivity of the neural-network architecture compared to the Slater-Jastrow ansatz. The benefits of explicitly encoding in the wave function point symmetries such as parity and time-reversal are also discussed. Leveraging on improved optimization methods and sampling techniques, the hidden-nucleon ansatz achieves an accuracy comparable to the numerically-exact hyperspherical harmonic method in light nuclei and to the auxiliary field diffusion Monte Carlo in $^{16}$ O. Thanks to its polynomial scaling with the number of nucleons, this method opens the way to highly-accurate quantum Monte Carlo studies of medium-mass nuclei.
nucl-thcond-mat.dis-nnquant-phPRResearch(2022)·67 citations
12
Effect of chiral nuclear forces on the neutrino mean free path in hot neutron matter
Isaac Vidana🇮🇹 · Domenico Logoteta🇮🇹 · Ignazio Bombaci🇮🇹
We study the role of chiral nuclear forces on the propagation of neutrinos in hot neutron matter. In particular, we analyze the convergence of the dynamical structure factor and the neutrino mean free path with the order of the power counting of the chiral forces, as well as the role of the regulator cut-off of these forces in the determination of these quantities. Single-particle energies and chemical potentials needed to calculate the dynamical structure factor are obtained within the Brueckner--Hartree--Fock approximation extended to finite temperature. Our results show that the dynamical structure factor and the neutrino mean free path depend on the cut-off only when the chiral potential is considered at leading order (LO) and next-to leading order (NLO), becoming this dependence strongly reduced at higher orders in the chiral power counting due to the role of three-nucleon forces that start to contribute at next-to-next-to leading order (N $^{2}$ LO) being, in particular, almost negligible at next-to-next-to-next-to leading order (N $^{3}$ LO). The neutrino mean free path is found to converge up to densities slightly below $\sim 0.15$ fm $^{- 3}$ when increasing the order of the chiral power counting, although no signal of convergence is found for densities above this value. The uncertainty associated with our order-by-order nuclear many-body calculation of the neutrino mean free path is roughly estimated from the difference between the results obtained at N $^{2}$ LO and N $^{3}$ LO, finding that it varies from about a few centimeters at low densities up to a bit less than $2$ meters at the largest one considered in this work, $0.3$ fm $^{- 3}$ .
nucl-thPRC(2022)·10 citations
13
Deuteron yields from LHC: Continuum correlations and in-medium effects
Benjamin Dönigus🇩🇪 · Gerd Röpke🇩🇪 · David Blaschke🇵🇱
To explain the production of light nuclei in heavy-ion collisions at extreme energies, we focus on the deuteron case. A Gibbs ensemble at chemical freeze-out is a prerequisite to investigate the non-equilibrium evolution of the expanding fireball. Quantum statistical approaches allow to describe correlations including bound state formation in the strongly interacting and hot system. We consider the virial approach to evaluate proton-neutron correlations. In generalization of the treatment of protons in pionic matter (pion-proton puzzle), the influence of the pion environment on deuteron-like correlations is evaluated using data for the pion-deuteron scattering phase shifts. Calculated yields for deuteron production are compared with the ones observed at the LHC.
nucl-thPRC(2022)·17 citations
14
Separating the impact of nuclear skin and nuclear deformation in high-energy isobar collisions
Jiangyong Jia🇺🇸 · Giuliano Giacalone🇩🇪 · Chunjian Zhang🇺🇸
Bulk nuclear structure properties, such as radii and deformations, leave distinct signatures in the final state of relativistic heavy-ion collisions. Isobaric collisions offer an easy route to establish explicit connections between the colliding nuclei's structure and the observable outcomes. Here, we investigate the effects of nuclear skin thickness and nuclear deformations on the elliptic flow ( $v_{2}$ ) and its fluctuations in high-energy $^{96}$ Ru+ $^{96}$ Ru and $^{96}$ Zr+ $^{96}$ Zr collisions. Our findings reveal that the difference in skin thickness between these isobars only influences the inherent ellipticity of the collision systems, $v_{2}^{rp}$ . In contrast, differences in nuclear deformations solely impact the fluctuations of $v_{2}$ around $v_{2}^{rp}$ . Hence, we have identified a data-driven method to disentangle the effects of nuclear skin and nuclear deformations, marking a significant step toward assessing the consistency of nuclear phenomena across energy scales.
nucl-thhep-phnucl-exPRL(2023)·74 citations
15
Fundamental-mode eigenfrequencies of neutral and charged twin neutron stars
Victor P. Goncalves🇧🇷 · José C. Jiménez🇧🇷 · Lucas Lazzari🇧🇷
We investigate the effects of rapid and slow conversions on the fundamental-mode eigenfrequencies of hybrid neutron stars having highly discontinuous transitions between hadronic and quark matter, the so-called twin stars. We analyze some characteristic cases in the available parameter space of the equations of state for the hadronic and quark phases. Furthermore, we also consider the possibility that these stellar configurations are electrically charged. Our results indicate that for neutral configurations under rapid conversions the stability window coincides with the usual stability criterion, i.e. $\partial M / \partial p_{c} > 0$ and that the two branches are disconnected. This discontinuity remains when electric charge is considered, but the usual criterion is not sufficient to determine the star's stability. On the other hand, slow conversions connect initially disconnected branches and increase the stability window of the hybrid configurations. For both conversion speeds, the presence of electric charge diminishes the magnitude of the eigenfrequencies and its stability window.
nucl-thhep-phEPJC(2022)·10 citations
16
Analytical calculations of the Quantum Tsallis thermodynamic variables
Ayman Hussein🇪🇬 · Trambak Bhattacharyya🇷🇺
In this article, we provide an account of analytical results related to the Tsallis thermodynamics that have been the subject matter of a lot of studies in the field of high-energy collisions. After reviewing the results for the classical case in the massless limit and for arbitrarily massive classical particles, we compute the quantum thermodynamic variables. For the first time, the analytical formula for the pressure of a Tsallis-like gas of massive bosons has been obtained. Hence, this article serves both as a brief review of the knowledge gathered in this area, and as an original research that forwards the existing scholarship. The results of the present paper will be important in a plethora of studies in the field of high-energy collisions including the propagation of non-linear waves generated by the traversal of high-energy particles inside the quark-gluon plasma medium showing the features of non-extensivity.
↳ cond-mat.stat-mechhep-phhep-thnucl-thMDPI Physics(2022)·1 citation
17
Non-radial oscillations and global stellar properties of anisotropic compact stars using realistic equations of state
Elvis J. Aquino Curi · Luis B. Castro · Cesar V. Flores · César H. Lenzi
In this work, we have made a systematic study of how the gravitational wave frequency of the fundamental mode from compact stars is affected by anisotropic effects using realistic equations of state. Our study is an extension of the seminal research performed by Doneva [Phys. Rev. D 85 (2012) 124023], where a polytropic equation of state was used. To achieve our objective, we considered compact stars which were built by using equations of state in the framework of a relativistic mean field theory for the case of hadronic stars and in the framework of the MIT model for the case of quark stars. In order to obtain some pertinent information that could give us the possibility to detect the anisotropy in compact stars, we also studied and analized the behaviour of various global stellar quantities, e.g., gravitational redshift, stellar mass, radius, among others. We concluded that the anisotropic effects can have important consequences, which are strongly related to the anisotropic parameter and the equation of state of high density matter. Additionally, a comparison with observational data has been made and we have shown that the anisotropic parameter $λ$ can be used as a tuning parameter to reproduce mass and radius observational data of neutron stars.
↳ gr-qcastro-ph.HEastro-ph.SRhep-ph+1EPJC(2022)·37 citations
18
Nuclei near and at the proton dripline
Marek Pfützner · Chiara Mazzocchi
Nuclei in the vicinity of the proton dripline and beyond it are a fascinating realm within the chart of nuclei. In this chapter the main phenomena that characterize this domain and are not to be found elsewhere are explored. While moving away from the $β$ -stability valley towards the proton dripline, phenomena like very exotic decay modes such as $β$ -delayed (multi-) particle emission, and proton-, or two-proton radioactivity are encountered. Landmark nuclei are here two isotopes with magic proton and neutron numbers, $^{48}$ Ni and $^{100}$ Sn. Moreover, proton-rich nuclei ( $N < Z$ ) display other interesting features, like breaking of isospin symmetry with consequent asymmetry in the energy spectra between mirror nuclei, the so-called Thomas-Ehrmann shift, or the phenomenon of proton-halo. Last but not least, nuclei close to the proton dripline play a very important role in nucleosynthesis, since they take part in the rapid-proton capture process and their properties are crucial in defining the flow followed and its termination close to $^{100}$ Sn.
↳ nucl-exnucl-th1 citation
19
Nucleon form factors and parton distributions in nonlocal chiral effective theory
P. Wang🇨🇳 · Fangcheng He🇨🇳 · Chueng-Ryong Ji🇺🇸 · W. Melnitchouk🇺🇸
We present a review of recent applications of nonlocal chiral effective theory to hadron structure studies. Starting from a nonlocal meson--baryon effective chiral Lagrangian, we show how the introduction of a correlation function representing the finite extent of hadrons regularizes the meson loop integrals and introduces momentum dependence in vertex form factors in a gauge invariant manner. We apply the framework to the calculation of nucleon electromagnetic form factors, unpolarized and polarized parton distributions, as well as transverse momentum dependent distributions and generalized parton distributions. Assuming that the nonlocal behavior is a general property of all interactions, we also discuss the application to the lepton anomalous magnetic moment in nonlocal QED.
↳ hep-phhep-exhep-latnucl-thPPNP(2023)·14 citations
20
Oscillation Modes and Gravitational Waves from Strangeon Stars
Hong-Bo Li🇨🇳 · Yong Gao🇨🇳 · Lijing Shao🇨🇳 · Ren-Xin Xu🇨🇳 · Rui Xu🇨🇳
The strong interaction at low energy scales determines the equation of state (EOS) of supranuclear matters in neutron stars (NSs). It is conjectured that the bulk dense matter may be composed of strangeons, which are quark clusters with nearly equal numbers of $u$ , $d$ , and $s$ quarks. To characterize the strong-repulsive interaction at short distance and the nonrelativistic nature of strangeons, a phenomenological Lennard-Jones model with two parameters is used to describe the EOS of strangeon stars (SSs). For the first time, we investigate the oscillation modes of non-rotating SSs and obtain their frequencies for various parameterizations of the EOS. We find that the properties of radial oscillations of SSs are different from those of NSs, especially for stars with relatively low central energy densities. Moreover, we calculate the $f$ -mode frequency of nonradial oscillations of SSs within the relativistic Cowling approximation. The frequencies of the $f$ -mode of SSs are found to be in the range from $6.7$ kHz to $8.7 kHz$ . Finally, we study the universal relations between the $f$ -mode frequency and global properties of SSs, such as the compactness and the tidal deformability. The results we obtained are relevant to pulsar timing and gravitational waves, and will help to probe NSs' EOSs and infer nonperturbative behaviours in quantum chromodynamics.
↳ gr-qcastro-ph.HEnucl-thMNRAS(2022)·28 citations
21
Search for possible alpha-condensate states in $^{20}$ Ne
A.S. Demyanova (1) · A.N. Danilov (1) · S.A. Goncharov (2) · V.I. Starastsin (1,3) · T.I Leonova (1,3) ((1) National Research Centre Kurchatov Institute, Moscow, Russia, (2) Lomonosov Moscow State University, Moscow, Russia, (3) National Research Nuclear University MEPhI, Moscow, Russia)
The root mean square radii of $^{20}$ Ne in the short-lived excited states were experimentally deduced for the first time from the analyses of $α$ + $^{20}$ Ne diffraction scattering. Differential cross sections of the elastic and inelastic $α$ + $^{20}$ Ne scattering in the incident energy range from a few MeV/nucleon up to 100 MeV/nucleon were analyzed by the modified diffraction model. No significant radius enhancement for the members of K $^{π}$ = 0 $_{1}^{+}$ and K $^{π}$ = 2 $^{-}$ bands in comparison with the ground state was observed. At the same time 20 % radius enhancement was obtained for the K $^{π}$ = 0 $_{1}^{-}$ band members. Moreover, for the 0 $_{2}^{+}$ state located above $α$ -emission threshold increased radius was observed. This result can speak in favor of possible $α$ -condensate structure of the 0 $_{2}^{+}$ state and can be considered as a possible analog of the famous 7.65-MeV 0 $_{2}^{+}$ Hoyle state of $^{12}$ C.
↳ nucl-exnucl-th0 citations
22
Near-BPS Skyrmions
Sven Bjarke Gudnason🇨🇳 · Marco Barsanti🇮🇹 · Stefano Bolognesi🇮🇹
We consider the Skyrme model in the near-BPS limit. The BPS part is made of the sextic term plus a potential and the deformation is made of the standard massive Skyrme model controlled by a small parameter $ϵ ≪ 1$ . In order to keep the perturbation under theoretical and computational control, we find a model for which BPS Skyrmions have compact support, henceforth denoted as compactons, and the spherically symmetric $B = 1$ Skyrmion represents the most stable solution. We use the $ϵ$ -expansion scheme to systematically calculate the corrections to the energy and compare with the exact numerical computations in the $B = 1$ sector. Finally, we use the $ϵ$ -expansion scheme to calculate the bound state of two $B = 1$ Skyrmions and its binding energy, which corresponds, prior to quantization, to the deuteron in our model.
↳ hep-thnucl-thJHEP(2022)·5 citations
23
Prospects of searching for unstable nucleus states in relativistic nuclear fragmentation
D.A. Aretemenkov · V. Bradnova · O.N Kashanskaya · N.V. Kondratieva · N.K. Kornegrutsa · E. Mitsova · N.G. Peresadko · V.V. Rusakova · R. Stanoeva · A.A. Zaitsev · P.I. Zarubin · I.G. Zarubina
The article is dedicated to the experimental study in the relativistic approach to the problems of nuclear cluster physics for the prospects of the \href{http://becquerel.jinr.ru/}{BECQUEREL} experiment. The nuclear emulsion method applied in this experiment makes it possible to study thoroughly the relativistic final states in the fragmentation of nuclei. The focus of the presented research is the dynamics of emergence of the $^{8}$ Be nucleus and the Hoyle state, as well as the search for the 4 $α$ -particle condensate decaying via the above nuclear states. In this context, the analysis of exposure to $^{84}$ Kr nuclei at 950 MeV/nucleon is shown. As a continuation of the study of light nuclei, we have demonstrated the search for the isobar-analogue state of the $^{13}$ N nucleus in the fragmentation of $^{14}$ N nuclei at 2 GeV/nucleon.
↳ nucl-exnucl-thPhys.Atom.Nucl.(2022)·4 citations
24
Renormalised spectral flows
Jens Braun🇩🇪 · Yong-rui Chen🇨🇳 · Wei-jie Fu🇨🇳 · Andreas Geißel🇩🇪 · Jan Horak🇩🇪 · Chuang Huang🇨🇳 · Friederike Ihssen🇩🇪 · Jan M. Pawlowski🇩🇪 · Manuel Reichert🇬🇧 · Fabian Rennecke🇩🇪 · Yang-yang Tan🇨🇳 · Sebastian Töpfel🇩🇪 · Jonas Wessely🇩🇪 · Nicolas Wink🇩🇪
We derive renormalised finite functional flow equations for quantum field theories in real and imaginary time that incorporate scale transformations of the renormalisation conditions, hence implementing a flowing renormalisation. The flows are manifestly finite in general non-perturbative truncation schemes also for regularisation schemes that do not implement an infrared suppression of the loops in the flow. Specifically, this formulation includes finite functional flows for the effective action with a spectral Callan-Symanzik cutoff, and therefore gives access to Lorentz invariant spectral flows. The functional setup is fully non-perturbative and allows for the spectral treatment of general theories. In particular, this includes theories that do not admit a perturbative renormalisation such as asymptotically safe theories. Finally, the application of the Lorentz invariant spectral functional renormalisation group is briefly discussed for theories ranging from real scalar and Yukawa theories to gauge theories and quantum gravity.
↳ hep-thhep-phnucl-thSciPost Phys.Core(2023)·65 citations

Affiliations

first authorsco-authorsvia INSPIRE