Nuclear Theory·nucl-th

Tuesday·December 11, 2018

16 papers—11 primary·5 cross-listed

01
Nuclear binding energy predictions based on BP neural network
B. B. Jiao🇨🇳
Nuclear masses are of great importance in nuclear physics and astrophysics. Descriptive experimental data on nuclear masses and the prediction of unknown masses based on residual proton-neutron interactions are a focus in nuclear physics. The accuracy of the residual interaction determines the accuracy of the nuclear mass values, so the study of residual interactions is essential. Before we carry out this study, there are many papers using artificial neural networks in nuclear physics. But no one uses BP neural network to study residual interactions. In this paper, we obtained a description and prediction model for residual interactions based on BP neural network. By combining experimental values with residual interactions model, we successfully calculate the nuclear masses of $A \geq 100$ . Results demonstrate that the differences between our calculated values and experimental values (AME2003, AME2012 and AME2016) show that the root-mean-squared deviations (RMSDs) are small (comparing with AME2003, the odd-A nuclei RMSD and the even-A nuclei RMSD are 112 keV and 128 keV; comparing with AME2012, the odd-A nuclei RMSD and the even-A nuclei RMSD are 103 keV and 121 keV; comparing with AME2016, the RMSD of odd-A nuclei and even-A nuclei are 106 keV and 122 keV, respectively). In addition, we obtained some predicted masses based on AME2003 and AME2012, the predicted values have good accuracy and compared well with experimental values (AME2012 and AME2016). The results show that the study of residual interactions using the proposed BP neural network method is feasible and accurate. This method is helpful for analyzing and extracting useful information from a large number of experimental values and then providing a reference for discovering physical laws and support for physical experiments.
nucl-thIJMPE(2020)·4 citations
02
The contribution of chiral three-body forces to the monopole component of the effective shell-model Hamiltonian
Y. Z. Ma · L. Coraggio · L. De Angelis · T. Fukui · A. Gargano · N. Itaco · F. R. Xu
We present a study of the role played by realistic three-body forces in providing a reliable monopole component of the effective shell-model Hamiltonian. To this end, starting from a nuclear potential built up within the chiral perturbation theory, we derive effective shell-model Hamiltonians with and without the contribution of the three-body potential and compare the results of shell-model calculations with a set of observables that evidence shell-evolution properties. The testing ground of our investigation are nuclei belonging to fp shell, since the shell evolution towards shell closures in 48Ca and 56Ni provides a paradigm for shell-model Hamiltonians. Our analysis shows that only by including contributions of the three-body force the monopole component of the effective shell-model Hamiltonian is then able to reproduce the experimental shell evolution towards and beyond the closure at N=28.
nucl-thPRC(2019)·43 citations
03
Implications of nuclear interaction for nuclear structure and astrophysics within the relativistic mean-field model
Bharat Kumar🇮🇳
In this dissertation, we have studied the implications of nuclear interaction for nuclear structure and astrophysics within the relativistic mean-field (RMF) model.
nucl-thgr-qc2 citations
04
Dispersive Evaluation of the Inner Radiative Correction in Neutron and Nuclear $β$ -decay
Chien Yeah Seng🇨🇳 · Mikhail Gorchtein🇩🇪 · Michael J. Ramsey-Musolf🇺🇸
We propose a novel dispersive treatment of the so-called inner radiative correction to the neutron and nuclear $β$ -decay. We show that it requires knowledge of the parity-violating structure function $F_{3}^{(0)}$ that arises from the interference of the axial vector charged current and the isoscalar part of the electromagnetic current. By isospin symmetry, we relate this structure function to the charged current inelastic scattering of neutrinos and antineutrinos. Applying this new data-driven analysis we obtain a new, more precise evaluation for the universal radiative correction $Δ_{R}^{V, n e w} = 0.02467 (22)$ that supersedes the previous estimate by Marciano and Sirlin, $Δ_{R}^{V} = 0.02361 (38)$ . The substantial shift in the central value of $Δ_{R}^{V}$ reflects in a respective shift of $V_{u d}$ and a considerable tension in the unitarity constraint on the first row of the CKM matrix which is used as one of the most stringent constraints on New Physics contributions in the charged current sector. We also point out that dispersion relations offer a unifying tool for treating hadronic and nuclear corrections within the same framework. We explore the potential of the dispersion relations for addressing the nuclear structure corrections absorbed in the $F t$ values, a crucial ingredient alongside $Δ_{R}^{V}$ in extracting $V_{u d}$ from superallowed nuclear decays.
nucl-thhep-phnucl-exPRD(2019)·204 citations
05
Properties of Neutron Stars with hyperon cores in parameterized hydrostatic conditions
Debashree Sen🇮🇳 · Kinjal Banerjee🇮🇳 · T.K. Jha🇮🇳
Models of neutron stars (NSs) with hyperon cores are constructed with an effective chiral model in mean-field approximation. The hyperon couplings are fixed by reproducing their experimentally determined binding energies. The impact of these couplings on population of different particles and the equation of state (EoS) are studied in this work. The global properties of NSs like gravitational mass, radius, baryonic mass and central density are calculated using parameterized Tolman-Oppenheimer-Volkoff equations (PTOV) with special emphasis on two effects of pressure - one contributing to total mass density and the other to self gravity of the star. We find that with PTOV solutions in static conditions, a softer EoS (including hyperons) can also lead to massive stellar configurations of NSs, which are in well agreement with the observed maximum mass bound of $\approx 2 M_{⊙}$ (PSR J0348-0432). Estimates of $R_{1.4}$ and $R_{1.6}$ , obtained with the PTOV equations are consistent with the recent findings of the same from the data analysis of gravitational waves (GW170817) observation. Keywords: Neutron Star; Hyperons; Equation of State; parameterized Tolman-Oppenheimer-Volkoff equations
nucl-thastro-ph.HEgr-qchep-phIJMPE(2019)·15 citations
06
Non-flow effects in three-particle mixed-harmonic azimuthal correlations in small collision systems
Chunjian Zhang🇨🇳 · Jiangyong Jia🇺🇸 · Jun Xu🇨🇳
The Multi-particle technique has been used to unravel the nature of the long-range collectivity in small collision systems. A large three-particle mixed-harmonic correlation signal was recently observed by the ATLAS Collaboration, but the role of non-flow correlations is not yet studied. We estimate the influence of non-flow correlations to the three-particle correlators in $pp$ and $p$ +Pb collisions using PYTHIA and HIJING models, and compare with the ATLAS results. The large non-flow effects from the jet and dijet production is found to be largely suppressed in $p$ +Pb collisions using the subevent cumulant method by calculating the azimuthal correlation between two or more longitudinal pseudorapidity ranges. Depending on the experimental subevent method, however, the non-flow effects may still be significant in $pp$ collisions.
nucl-thnucl-exPLB(2019)·14 citations
07
Hyperonic Neutron Star Matter in Light of GW170817
William M. Spinella🇺🇸 · Fridolin Weber🇺🇸
Since 2013 the mass of pulsar PSR J0348+0432 ( $M = 2.01 M_{⊙}$ ) has provided a tight constraint on neutron star equation of state. However, a number of different analyses of the recently detected BNS merger (GW170817) point to a maximum neutron star mass around $2.16 M_{⊙}$ . In addition, a recent study determined the mass of the millisecond pulsar PSR J2215+5135 to be $2.2 7_{- 0.15}^{+ 0.17} M_{⊙}$ . In this work we investigate the presence of hyperons in neutron star matter in light of these new mass measurements using equations of state calculated in the relativistic mean-field approximation. Particular attention is paid to the use of the available empirical data from the study of hypernuclei and that of the SU(3) symmetry relations in fixing the meson-hyperon coupling constants. We find that hyperonic equations of state with reasonable choices for the meson-hyperon coupling constants can satisfy these new mass constraints, with hyperons potentially accounting for more than 10% of the baryons in the core of a neutron star.
nucl-thAstron.Nachr.(2019)·23 citations
08
Meson-baryon scattering up to the next-to-next-to-leading order in covariant baryon chiral perturbation theory
Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳 · Xiu-Lei Ren🇩🇪 · Meng-Lin Du🇩🇪
We study the scattering of a pseudoscalar meson off one ground state octet baryon in covariant baryon chiral perturbation theory (BChPT) up to the next-to-next-to-leading order. The inherent power counting breaking terms are removed within extended-on-mass-shell scheme. We perform the first combined study of the pion-nucleon and kaon-nucleon scattering data in covariant BChPT and show that it can provide a reasonable description of the experimental data. In addition, we find that it is possible to fit the experimental baryon masses and the pion-nucleon and kaon-nucleon scattering data simultaneously at this order, thus providing a consistent check on covariant BChPT. We compare the scattering lengths of all the pertinent channels with available experimental data and those of other approaches. In addition, we have studied the leading order contributions of the virtual decuplet and found that they can improve the description of the $π N$ phase shifts near the $Δ (1232)$ peak, while they have negligible effects on the description of the $K N$ phase shifts.
nucl-thhep-lathep-phPRD(2019)·23 citations
09
Two-photon exchange on neutron and the hyperfine splitting
Oleksandr Tomalak🇺🇸
We calculate the contribution from the two-photon exchange on the neutron to the hyperfine splitting of S energy levels. We update the value of the neutron Zemach radius, estimate total recoil and polarizability corrections. The resulting two-photon exchange in electronic atoms exceeds by an order of magnitude the leading Zemach term and has different sign both in electronic and muonic hydrogen.
nucl-thhep-phnucl-exphysics.atom-phPRD(2019)·12 citations
10
Theoretical predictions for the magnetic dipole moment of $^{229 m}$ Th
Nikolay Minkov🇧🇬 · Adriana Pálffy🇩🇪
A recent laser spectroscopy experiment [J. Thielking et al., Nature (London) 556, 321 (2018)] has determined for the first time the magnetic dipole moment of the 7.8 eV isomeric state $^{229 m}$ Th. The measured value differs by a factor of approximately 5 from previous nuclear theory predictions based on the Nilsson model, raising questions about our understanding of the underlying nuclear structure. Here, we present a new theoretical prediction based on a nuclear model with coupled collective quadrupole-octupole and single-particle motions. Our calculations yield an isomer magnetic dipole moment of $μ_{I S} = - 0.35 μ_{N}$ in surprisingly good agreement with the experimentally determined value of $- 0.37 (6) μ_{N}$ , while overestimating the ground state dipole moment by a factor 1.4. The model provides further information on the states' parity mixing, the role and strength of the Coriolis mixing and the most probable value of the gyromagnetic ratio $g_{R}$ and its consequences for the transition probability $B (M 1)$ .
nucl-thPRL(2019)·39 citations
11
Symmetry restoration in the mean-field description of proton-neutron pairing
A. M. Romero · J. Dobaczewski · A. Pastore
We show that the symmetry-restored paired mean-field states (quasiparticle vacua) properly account for isoscalar versus isovector nuclear pairing properties. Full particle-number, spin, and isospin symmetries are restored in a simple SO(8) proton-neutron pairing model, and prospects to implement a similar approach in a realistic setting are delineated. Our results show that, provided all symmetries are restored, the pictures based on pair-condensate and quartet-condensate wave functions represent equivalent ways of looking at the physics of nuclear proton-neutron pairing.
nucl-thPLB(2019)·30 citations
12
A holographic description of heavy-flavoured baryonic matter decay involving glueball
Si-wen Li🇨🇳
We holographically investigate the decay of heavy-flavoured baryonic hadron involving glueball by using the Witten-Sakai-Sugimoto model. Since baryon in this model is recognized as the D4-brane wrapped on $S^{4}$ and the glueball field is identified as the bulk gravitational fluctuations, the interaction of the bulk graviton and the baryon brane could be naturally interpreted as glueball-baryon interaction through the holography which is nothing but the close-open string interaction in string theory. In order to take account into the heavy flavour, an extra pair of heavy-flavoured branes separated from the other flavour branes with a heavy-light open string is embedded into the bulk. Due to the finite separation of the flavour branes, the heavy-light string creates massive multiplets which could be identified as the heavy-light meson fields in this model. As the baryon brane on the other hand could be equivalently described by the instanton configuration on the flavour brane, we solve the equations of motion for the heavy-light fields with the Belavin-Polyakov-Schwarz-Tyupkin (BPST) instanton solution for the $N_{f} = 2$ flavoured gauge fields. Then with the solutions, we evaluate the soliton mass by deriving the flavoured onshell action in strongly coupling limit and heavy quark limit. After the collectivization and quantization, the quantum mechanical system for glueball and heavy-flavoured baryon is obtained in which the effective Hamiltonian is time-dependent. Finally we use the standard technique for the time-dependent quantum mechanical system to analyze the decay of heavy-flavoured baryon involving glueball and we find one of the decay process might correspond to the decay of baryonic B-meson involving the glueball candidate $f_{0} (1710)$ . This work is a holographic approach to study the decay of heavy-flavoured hadron in nuclear physics.
↳ hep-thnucl-thPRD(2019)·6 citations
13
Exotic $Ω_{c}^{0}$ baryons from meson-baryon scattering
Gloria Montana🇪🇸 · Angels Ramos🇪🇸 · Albert Feijoo🇨🇿
A meson-baryon interaction in the charm $+ 1$ , strangeness $- 2$ and isospin $0$ sector is built from a t-channel vector meson exchange model employing effective Lagrangians. The implementation of coupled-channel unitarization in the s-wave scattering amplitudes gives rise to two structures that have similar masses and widths to those of the $Ω_{c} (3050)^{0}$ and $Ω_{c} (3090)^{0}$ states recently observed by the LHCb collaboration. A meson-baryon molecular interpretation of these resonances would assign their spin-parity to be $J^{P} = 1/ 2^{-}$ .
↳ hep-phnucl-thJ.Phys.Conf.Ser.(2019)·1 citation
14
The molecular nature of some $Ω_{c}^{0}$ states
Gloria Montana🇪🇸 · Angels Ramos🇪🇸 · Albert Feijoo🇨🇿
A vector meson exchange model based on effective Lagrangians is used to build the meson--baryon interaction in the charm $+ 1$ , strangeness $- 2$ and isospin $0$ sector. The s-wave scattering amplitudes resulting from the unitarization in coupled-channels show two resonances with masses and widths that are in very good agreement with those of the experimental $Ω_{c} (3050)^{0}$ and $Ω_{c} (3090)^{0}$ states observed by the LHCb collaboration. The interpretation of these resonances as pseudoscalar meson--baryon molecules would mean the assignment $J^{P} = 1/ 2^{-}$ to their spin--parity.
↳ hep-phnucl-thSpringer Proc.Phys.(2020)·1 citation
15
Quasi equilibrium state of expanding quantum fields and two-pion Bose-Einstein correlations in $pp$ collisions at the LHC
S.V. Akkelin🇺🇦
We argue that the two-particle momentum correlation functions of high-multiplicity $p + p$ collisions at the LHC provide a signal for a ground state structure of a quasi equilibrium state of the longitudinally boost-invariant expanding quantum field which lies in the future light cone of a collision. The physical picture is that pions are produced by the expanding quantum emitter with two different scales approximately attributed to the expanding ideal gas in local equilibrium state and ground-state condensate. Specifically, we show that the effect of suppressing the two-particle Bose-Einstein momentum correlation functions increases with increasing transverse momentum of a like-sign pion pair due to different momentum-dependence of the corresponding particle emission regions.
↳ hep-phhep-exnucl-exnucl-thEPJA(2019)·7 citations
16
Computing the gluon Sivers function at small- $x$
Xiaojun Yao🇺🇸 · Yoshikazu Hagiwara🇯🇵 · Yoshitaka Hatta🇺🇸
We compute the gluon Sivers function $f_{1 T}^{⊥ g} (x, k_{⊥})$ of the transversely polarized nucleon at small- $x$ by exploiting the known connection between the dipole gluon Sivers function and the Odderon. We numerically solve the evolution equation for the Odderon both in the linear and nonlinear regimes. While we find that the $x$ and $k_{⊥}$ dependences of the Sivers function do not factorize as a result of the quantum evolution, factorization breaking is not numerically significant, and is much milder than what one expects in the case of unpolarized TMDs. We also point out the possibility that, due to the presence of a node in the Sivers function, single spin asymmetry for open charm production in semi-inclusive deep inelastic scattering flips signs as the transverse momentum of D-mesons is varied. This can be tested at the future Electron-Ion Collider.
↳ hep-phhep-exnucl-thPLB(2019)·34 citations

Affiliations

first authorsco-authorsvia INSPIRE