Nuclear Theory·nucl-th

Friday·April 30, 2021

11 papers—3 primary·8 cross-listed

04
A bound on the nucleon Druck-term from chiral EFT in curved space-time and mechanical stability conditions
Jambul Gegelia🇩🇪 · Maxim V. Polyakov🇩🇪
Using dispersive representations of the nucleon gravitational form factors, the results for their absorptive parts from chiral effective field theory in curved space-time, and the mechanical stability conditions, we obtain a model independent inequality for the value of the gravitational $D (t)$ form factor at zero momentum transfer (Druck-term). In particular, the obtained inequality leads to a conservative bound on the Druck-term in the chiral limit $D \leq - 0.95 (9)$ . This bound implies the restriction on the low-energy constant $c_{8}$ of the effective chiral action for nucleons and pions in the presence of an external gravitational field, $c_{8} \leq - 1.1 (1)$ GeV $^{- 1}$ . For the physical pion mass we obtain a model independent bound $D \leq - 0.20 (2)$ .
↳ hep-phhep-exnucl-thPLB(2021)·28 citations
05
The Lowest Broad Alpha Cluster Resonances in $^{19}$ F
A. Volya🇺🇸 · V. Z. Goldberg🇺🇸 · A. K. Nurmukhanbetova🇰🇿 · D. K. Nauruzbayev🇰🇿 · G. V. Rogachev🇺🇸
There is a deep astrophysical interest in the structure of $^{19}$ F states close to the alpha decay threshold. The nuclear structure of these states is important for understanding of the development of $α$ clustering in the $^{20}$ Ne region. Emergence of clustered states and generally states that favor coupling to reaction channels near the corresponding decay thresholds is currently of special interest in theoretical physics. Excitation function for $^{15}$ N( $α$ , $α$ ) elastic scattering was measured by the TTIK method. These new data together with old, high energy resolution data, were analyzed using the R matrix approach. $^{19}$ F nuclear structure was calculated using configuration interaction methods with the recently developed effective interaction Hamiltonian. The parameters of broad low spin $ℓ = 0$ and 1 relative partial wave resonances close to the $α$ decay threshold in $^{19}$ F were identified. Detailed theoretical analysis was carried out identifying all states coupled to the $ℓ = 0$ and 1 alpha cluster channels. Considering hierarchy of states with different harmonic oscillator shell excitations allows to evaluate coupling to the alpha channels with different number of nodes in the relative wave function and helps to explain the distribution of the clustering strength and emergence of broad clustering resonances. Comparison of clustering in $^{20}$ Ne into $^{16}$ O+ $α$ and consideration of spin-orbit splitting of the $^{15}$ N+ $α$ channel provides additional evidence. Detailed analysis of new and old experimental data allows to identify a series of $α$ clustering resonances in $^{19}$ F and to assess the distribution of the clustering strength which is of importance to questions of astrophysics and for theoretical understanding of many-body physics and emergence of clustering in loosely bound or unstable nuclei.
↳ nucl-exnucl-thPRC(2022)·9 citations
06
Survival probabilities of charmonia as a clue to measure transient magnetic fields
Sachio Iwasaki🇯🇵 · Daisuke Jido🇯🇵 · Makoto Oka🇯🇵 · Kei Suzuki🇯🇵
We investigate time evolution of $S$ -wave charmonium populations under a time-dependent homogeneous magnetic field and evaluate survival probabilities of the low-lying charmonia to the goal of estimating the magnetic field strength at heavy-ion collisions. Our approach implements mixing between different spin eigenstates and transitions to radially excited states. We show that the survival probabilities can change even by an extremely short magnetic field. Furthermore, we find that the survival probabilities depend on the initial spin states. We propose the sum of the survival probabilities over spin partners as an observable insensitive to the initial states. We also find that the sum can be approximately given as a function of $σ B_{0}^{2}$ with a duration time $σ$ and the maximum strength of the magnetic field $B_{0}$ .
↳ hep-phhep-exnucl-exnucl-thPLB(2021)·9 citations
07
A review of quarkonia under strong magnetic fields
Sachio Iwasaki🇯🇵 · Makoto Oka🇯🇵 · Kei Suzuki🇯🇵
We review the properties of quarkonia under strong magnetic fields. The main phenomena are (i) mixing between different spin eigenstates, (ii) quark Landau levels and deformation of wave function, (iii) modification of $Q ˉ Q$ potential, and (iv) the motional Stark effect. For theoretical approaches, we review (i) constituent quark models, (ii) effective Lagrangians, (iii) QCD sum rules, and (iv) holographic approaches.
↳ hep-phhep-exhep-latnucl-ex+1EPJA(2021)·46 citations
08
Thermomagnetic modification of the anomalous magnetic moment of quarks using the NJL model
Snigdha Ghosh🇮🇳 · Nilanjan Chaudhuri🇮🇳 · Pradip Roy🇮🇳 · Sourav Sarkar🇮🇳
The effective photon-quark-antiquark ( $γ q q$ ) vertex function is evaluated at finite temperature in the presence of an arbitrary external magnetic field using the two-flavor gauged Nambu--Jona-Lasinio (NJL) model in the mean field approximation. The lowest order diagram contributing to the magnetic form factor and the anomalous magnetic moment (AMM) of the quarks is calculated at finite temperature and external magnetic field using the imaginary time formalism of finite temperature field theory and the Schwinger proper time formalism. The Schwinger propagator including all the Landau levels with non-zero AMM of the dressed quarks is considered while calculating the loop diagram. Using sharp as well as smooth three momentum cutoff, we regularize the UV divergences arising from the vertex function and the parameters of our model are chosen to reproduce the well known phenomenological quantities at zero temperature and zero magnetic field, such as pion-decay constant ( $f_{π}$ ), vacuum quark condensate, vacuum pion mass ( $m_{π}$ ) as well as the magnetic moments of proton and neutron. We then study the temperature and magnetic field dependence of the AMM and constituent mass of the quark. We found that, the AMM as well as the constituent quark mass are large at the chiral symmetry broken phase in the low temperature region. Around the pseudo-chiral phase transition they decrease rapidly and at high temperatures both of them approach vanishingly small values in the symmetry restored phase.
↳ hep-phnucl-thPRD(2021)·19 citations
09
Unveiling the pole structure of S-matrix using deep learning
Denny Lane B. Sombillo🇵🇭 · Yoichi Ikeda🇯🇵 · Toru Sato🇯🇵 · Atsushi Hosaka🇯🇵
Particle scattering is a powerful tool to unveil the nature of various subatomic phenomena. The key quantity is the scattering amplitude whose analytic structure carries the information of the quantum states. In this work, we demonstrate our first step attempt to extract the pole configuration of inelastic scatterings using the deep learning method. Among various problems, motivated by the recent new hadron phenomena, we develop a curriculum learning method of deep neural network to analyze coupled channel scattering problems. We show how effectively the method works to extract the pole configuration associated with resonances in the $π N$ scatterings.
↳ hep-phhep-exnucl-exnucl-th+1Rev.Mex.Fis.Suppl.(2022)·10 citations
10
Initial- and final-state temperatures of emission source from differential cross-section in squared momentum transfer in high energy collisions
Qi Wang🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿
The differential cross-section in squared momentum transfer of $ρ$ , $ρ^{0}$ , $ω$ , $ϕ$ , $f_{0} (980)$ , $f_{1} (1285)$ , $f_{0} (1370)$ , $f_{1} (1420)$ , $f_{0} (1500)$ , and $J / ψ$ produced in high energy virtual photon-proton ( $γ$ $^{*} p$ ), photon-proton ( $γ p$ ), and proton-proton ( $pp$ ) collisions measured by the H1, ZEUS, and WA102 Collaborations are analyzed by the Monte Carlo calculations. In the calculations, the Erlang distribution, Tsallis distribution, and Hagedorn function are separately used to describe the transverse momentum spectra of the emitted particles. Our results show that the initial- and final-state temperatures increase from lower squared photon virtuality to higher one, and decrease with increasing of center-of-mass energy.
↳ hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2021)·12 citations
11
Fourth- and fifth-order virial expansion of harmonically trapped fermions at unitarity
Y. Hou🇺🇸 · K. J. Morrell🇺🇸 · A. J. Czejdo🇺🇸 · J. E. Drut🇺🇸
By generalizing our automated algebra approach from homogeneous space to harmonically trapped systems, we have calculated the fourth- and fifth-order virial coefficients of universal spin-1/2 fermions in the unitary limit, confined in an isotropic harmonic potential. We present results for said coefficients as a function of trapping frequency (or, equivalently, temperature), which compare favorably with previous Monte Carlo calculations (available only at fourth order) as well as with our previous estimates in the untrapped limit (high temperature, low frequency). We use our estimates of the virial expansion, together with resummation techniques, to calculate the compressibility and spin susceptibility.
↳ cond-mat.quant-gasnucl-thPRResearch(2021)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE