Nuclear Theory·nucl-th

Tuesday·May 16, 2017

8 papers—4 primary·4 cross-listed

01
Interference Effect Between Neutron Direct and Resonance Capture Reactions For Neutron-Rich Nuclei
Futoshi Minato · Tokuro Fukui
Interference effect of neutron capture cross section between the compound and direct processes is investigated. The compound process is calculated by resonance parameters and the direct process by the potential mode. The interference effect is tested for neutron-rich $^{82}$ Ge and $^{134}$ Sn nuclei relevant to $r$ -process and light nucleus $^{13}$ C which is neutron poison in the $s$ -process and produces long-lived radioactive nucleus $^{14}$ C ( $T_{1/2} = 5700$ y). The interference effects in those nuclei are significant around resonances, and low energy region if $s$ -wave neutron direct capture is possible. Maxwellian averaged cross sections at $k T = 30$ and $300$ keV are also calculated, and the interference effect changes the Maxwellian averaged capture cross section largely depending on resonance position.
nucl-thnucl-exEPJ Web Conf.(2017)·1 citation
02
Solitonic excitations in collisions of superfluid nuclei: a qualitatively new phenomenon distinct from the Josephson effect
Kazuyuki Sekizawa · Gabriel Wlazłowski · Piotr Magierski
Recently, we have reported a novel role of pairing in low-energy heavy ion reactions at energies above the Coulomb barrier, which may have a detectable impact on reaction outcomes, such as the kinetic energy of fragments and the fusion cross section [arXiv:1611.10261, arXiv:1702.00069]. The phenomenon mimics the one studied experimentally with ultracold atomic gases, where two clouds of fermionic superfluids with different phases of the pairing fields are forced to merge, inducing various excitation modes of the pairing field. Although it originates from the phase difference of the pairing fields, the physics behind it is markedly different from the so-called Josephson effect. In this short contribution, we will briefly outline the results discussed in our recent papers and explain relations with the field of ultracold atomic gases.
nucl-thcond-mat.quant-gascond-mat.supr-connucl-exEPJ Web Conf.(2017)·11 citations
03
Configuration mixing in low-lying spectra of carbon hypernuclei
H. Xia🇨🇳 · H. Mei🇺🇸 · J. M. Yao🇺🇸
We perform a coupled-channels study of the low-lying states in $_{Λ}^{13, 15, 17, 19}$ C with a covariant energy density functional based microscopic particle-core coupling model. The energy differences of $1/ 2^{-}$ and $3/ 2^{-}$ states in $_{Λ}^{13}$ C and $_{Λ}^{15}$ C are predicted to be 0.25 MeV and 0.34 MeV, respectively. We find that configuration mixings in the $1/ 2^{-}$ and $3/ 2^{-}$ states of $_{Λ}^{15}$ C are the weakest among those of $_{Λ}^{13, 15, 17, 19}$ C. It indicates that $_{Λ}^{15}$ C provides the best candidate among the carbon hypernuclei to study the spin-orbit splitting of $p_{Λ}$ hyperon state.
nucl-thnucl-exSCPMA(2017)·10 citations
04
Empirical information on nuclear matter fourth-order symmetry energy from an extended nuclear mass formula
Rui Wang · Lie-Wen Chen
We establish a relation between the equation of state (EOS) of nuclear matter and the fourth-order symmetry energy $a_{sym, 4} (A)$ of finite nuclei in a semi-empirical nuclear mass formula by self-consistently considering the bulk, surface and Coulomb contributions to the nuclear mass. Such a relation allows us to extract information on nuclear matter fourth-order symmetry energy $E_{sym, 4} (ρ_{0})$ at normal nuclear density $ρ_{0}$ from analyzing nuclear mass data. Based on the recent precise extraction of $a_{sym, 4} (A)$ via the double difference of the "experimental" symmetry energy extracted from nuclear masses, for the first time, we estimate a value of $E_{sym, 4} (ρ_{0}) = 20.0 \pm 4.6$ MeV. Such a value of $E_{sym, 4} (ρ_{0})$ is significantly larger than the predictions from mean-field models and thus suggests the importance of considering the effects of beyond the mean-field approximation in nuclear matter calculations.
nucl-thastro-ph.SRnucl-exPLB(2017)·20 citations
05
Hadronic Correlation Functions in the Random Instanton-dyon Ensemble
Rasmus Larsen🇺🇸 · Edward Shuryak🇺🇸
It is known since 1980's that the instanton-induced 't Hooft effective Lagrangian not only can solve the so called $U (1) a$ problem, by making the $η^{'}$ meson heavy etc, but it can also lead to chiral symmetry breaking. In 1990's it was demonstrated that, taken to higher orders, this Lagrangian correctly reproduces effective forces in a large set of hadronic channels, mesonic and baryonic ones. Recent progress in understanding gauge topology at finite temperatures is related with the so called {\em instanton-dyons}, the constituents of the instantons. Some of them, called $L$ -dyons, possess the anti-periodic fermionic zero modes, and thus form a new version of the 't Hooft effective Lagrangian. This paper is our first study of a wide set of hadronic correlation function. We found that, at the lowest temperatures at which this approach is expected to be applicable, those may be well compatible with what is known about them based on phenomenological and lattice studies, provided $L$ and $M$ type dyons are strongly correlated.
↳ hep-phhep-latnucl-thPRD(2017)·6 citations
06
New Prospects for Detecting High-Energy Neutrinos from Nearby Supernovae
Kohta Murase (PSU)🇺🇸
Neutrinos from supernovae (SNe) are crucial probes of explosive phenomena at the deaths of massive stars and neutrino physics. High-energy neutrinos are produced through hadronic processes by cosmic rays, which are accelerated during interaction between the supernova (SN) ejecta and circumstellar material (CSM). Recent observations of extragalactic SNe have revealed that a dense CSM is commonly expelled by the progenitor star. We provide new quantitative predictions of time-dependent high-energy neutrino emission from diverse types of SNe. We show that IceCube and KM3Net can detect about 1000 events from a SN II-P (and about 300000 events from a SN IIn) at a distance of 10 kpc. The new model also enables us to critically optimize the time window for dedicated searches for nearby SNe. A successful detection will give us a multienergy neutrino view of SN physics and new opportunities to study neutrino properties, as well as clues to the cosmic-ray origin. GeV-TeV neutrinos may also be seen by KM3Net, Hyper-Kamiokande, and PINGU.
↳ astro-ph.HEastro-ph.SRhep-phnucl-thPRD(2018)·109 citations
07
Realizing Fulde-Ferrell Superfluids via a Dark-State Control of Feshbach Resonances
Lianyi He · Hui Hu · Xia-Ji Liu
We propose that the long-sought Fulde-Ferrell superfluidity with nonzero momentum pairing can be realized in ultracold two-component Fermi gases of $^{40}$ K or $^{6}$ Li atoms by optically tuning their magnetic Feshbach resonances via the creation of a closed-channel dark state with a Doppler-shifted Stark effect. In this scheme, two counterpropagating optical fields are applied to couple two molecular states in the closed channel to an excited molecular state, leading to a significant violation of Galilean invariance in the dark-state regime and hence to the possibility of Fulde-Ferrell superfluidity. We develop a field theoretical formulation for both two-body and many-body problems and predict that the Fulde-Ferrell state has remarkable properties, such as anisotropic single-particle dispersion relation, suppressed superfluid density at zero temperature, anisotropic sound velocity and rotonic collective mode. The latter two features can be experimentally probed using Bragg spectroscopy, providing a smoking-gun proof of Fulde-Ferrell superfluidity.
↳ cond-mat.quant-gascond-mat.supr-connucl-thPRL(2018)·7 citations
08
Ultrahigh-energy Cosmic-ray Nuclei from Black Hole Jets: Recycling Galactic Cosmic Rays through Shear Acceleration
Shigeo S. Kimura🇺🇸 · Kohta Murase🇺🇸 · B. Theodore Zhang🇨🇳
We perform Monte Carlo simulations of transrelativistic shear acceleration dedicated to a jet-cocoon system of active galactic nuclei. A certain fraction of galactic cosmic rays in a halo is entrained, and sufficiently high-energy particles can be injected to the reacceleration process and further accelerated up to 100 EeV. We show that the shear reacceleration mechanism leads to a hard spectrum of escaping cosmic rays, $d L_{E} / d E \propto E^{- 1} - E^{0}$ , distinct from a conventional $E^{- 2}$ spectrum. The supersolar abundance of ultrahigh-energy nuclei is achieved due to injections at TeV-PeV energies. As a result, we find that the highest-energy spectrum and mass composition can be reasonably explained by our model without contradictions with the anisotropy data.
↳ astro-ph.HEastro-ph.COhep-phnucl-thPRD(2018)·81 citations

Affiliations

first authorsco-authorsvia INSPIRE