Nuclear Theory·nucl-th

Friday·January 19, 2018

11 papers—7 primary·4 cross-listed

08
Observation of Narrow $N^{+} (1685)$ and $N^{0} (1685)$ Resonances in $γ N \to η π N$ Reactions
V. Kuznetsov · F. Mammoliti · F. Tortorici · V. Bellini · V. Brio · A. Gridnev · N. Kozlenko · G. Russo · A.Spatafora · M.L.Sperduto · V.Sumachev · C.Sutera
Observation of a narrow structure at $W \sim 1.68$ GeV in the excitation functions of some photon- and pion-induced reactions may signal a new narrow isospin-1/2 $N (1685)$ resonance. New data on the $γ N \to π η N$ reactions from GRAAL seems to reveal the signals of both $N^{+} (1685)$ and $N^{0} (1685)$ resonances.
↳ nucl-exhep-exhep-phnucl-thJETP Lett.(2017)·14 citations
09
The radiative corrections to double-Dalitz decays revisited
Karol Kampf🇨🇿 · Jiri Novotny🇨🇿 · Pablo Sanchez-Puertas🇨🇿
In this study, we revisit and complete the full next-to-leading order corrections to pseudoscalar double-Dalitz decays within the soft-photon approximation. Comparing to the previous study, we find small differences, which are nevertheless relevant for extracting information about the pseudoscalar transition form factors. Concerning the latter, these processes could offer the opportunity to test them-for the first time-in their double-virtual regime
↳ hep-phhep-exnucl-thPRD(2018)·28 citations
10
Pairing correlations across the superfluid phase transition in the unitary Fermi gas
S. Jensen🇺🇸 · C. N. Gilbreth🇺🇸 · Y. Alhassid🇺🇸
In the two-component Fermi gas with a contact interaction, a pseudogap regime can exist at temperatures between the superfluid critical temperature $T_{c}$ and a temperature $T^{*} > T_{c}$ . This regime is characterized by pairing correlations without superfluidity. However, in the unitary limit of infinite scattering length, the existence of this regime is still debated. To help address this, we have applied finite-temperature auxiliary-field quantum Monte Carlo (AFMC) to study the thermodynamics of the superfluid phase transition and signatures of the pseudogap in the spin-balanced homogeneous unitary Fermi gas. We present results at finite filling factor $ν ≃ 0.06$ for the condensate fraction, an energy-staggering pairing gap, the spin susceptibility, and the heat capacity, and compare them to experimental data when available. In contrast to previous AFMC simulations, our model space consists of the complete first Brillouin zone of the lattice, and our calculations are performed in the canonical ensemble of fixed particle number. The canonical ensemble AFMC framework enables the calculation of a model-independent gap, providing direct information on pairing correlations without the need for numerical analytic continuation. We use finite-size scaling to estimate $T_{c}$ at the corresponding filling factor. We find that the energy-staggering pairing gap vanishes above $T_{c}$ , showing no pseudogap effects, and that the spin susceptibility shows a substantially reduced signature of a spin gap compared to previously reported AFMC simulations.
↳ cond-mat.quant-gascond-mat.supr-conhep-latnucl-thPRL(2020)·32 citations
11
On the vacuum-polarization Uehling potential for a Fermi charge distribution
Jean-Christophe Pain🇫🇷
We present analytical formulas for the vacuum-polarization Uehling potential in the case where the finite size of the nucleus is modeled by a Fermi charge distribution. Using a Sommerfeld-type development, the potential is expressed in terms of multiple derivatives of a particular integral. The latter and its derivatives can be evaluated exactly in terms of Bickley-Naylor functions, which connection to the Uehling potential was already pointed out in the pure Coulomb case, and of usual Bessel functions of the second kind. The cusp and asymptotic expressions for the Uehling potential with a Fermi charge distribution are also provided. Analytical results for the higher-order-contribution Källèn-Sabry potential are given.
↳ quant-phhep-phhep-thnucl-th+1Eur.Phys.J.D(2018)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Observation of Narrow N+(1685) and N0(1685) Resonances in γN→ηπN Reactions

The radiative corrections to double-Dalitz decays revisited

Pairing correlations across the superfluid phase transition in the unitary Fermi gas

On the vacuum-polarization Uehling potential for a Fermi charge distribution

Affiliations

Observation of Narrow $N^{+} (1685)$ and $N^{0} (1685)$ Resonances in $γ N \to η π N$ Reactions