Nuclear Theory·nucl-th

Tuesday·August 13, 2019

12 papers—5 primary·7 cross-listed

06
Indirect Detection of Composite (Asymmetric) Dark Matter
Rakhi Mahbubani🇨🇭 · Michele Redi🇮🇹 · Andrea Tesi🇮🇹
Dark Matter can form bound states upon the emission of quanta of energy equal to the binding energy. The rate of this process is large for strongly-interacting Dark Matter, and further enhanced by long distance effects. The resulting monochromatic and diffuse $γ$ -rays can be tested in indirect detection experiments. If Dark Matter has electroweak charge, indirect signals include multiple observable photon lines for masses in the TeV range. Else if it couples only via a dark photon portal, diffuse spectra from dwarf galaxies and CMB reionization set powerful limits for masses below a TeV. This mechanism provides a powerful means of probing Asymmetric Dark Matter today.
↳ hep-phastro-ph.COhep-latnucl-thPRD(2020)·26 citations
07
Development and testing of an unstructured mesh method for whole plasma gyrokinetic simulations in realistic tokamak geometry
Z.X. Lu · Ph. Lauber · T. Hayward-Schneider · A. Bottino · M. Hoelzl
In this work, we have formulated and implemented a mixed unstructured mesh-based finite element (FE)-Fourier decomposition scheme for gyrokinetic simulations in realistic tokamak geometry. An efficient particle positioning (particle-triangle mapping) scheme for the charge deposition and field scattering using an intermediate grid as the search index for triangles has been implemented and a significant speed-up by a factor of $\sim 30$ is observed as compared with the brute force scheme for a medium-size simulation. The TRIMEG (TRIangular MEsh based Gyrokinetic) code has been developed. As an application, the ion temperature gradient (ITG) mode is simulated using the simplified gyrokinetic Vlasov-Poisson model. Our simulation and that using the ORB5 code for the DIII-D Cyclone case show reasonable agreement. As an additional application, ITG simulations using an ASDEX Upgrade equilibrium have been performed with density and temperature gradient profiles similar to the Cyclone case. Capabilities of the TRIMEG code for simulations with realistic experimental equilibria in the plasma core and in the whole plasma volume with open field lines are demonstrated.
↳ physics.plasm-phnucl-thphysics.comp-phPhys.Plasmas(2019)·0 citations
08
Constraints for stellar electron-capture rates on $^{86}$ Kr via the $^{86}$ Kr( $t$ , $^{3}$ He $+ γ$ ) $^{86}$ Br reaction and the implications for core-collapse supernovae
R. Titus · E.M. Ney · R.G.T. Zegers · D. Bazin · J. Belarge · P.C. Bender · B.A. Brown · C.M. Campbell · B. Elman · J. Engel · A. Gade · B. Gao and 11 other authors
In the late stages of stellar core-collapse, prior to core bounce, electron captures on medium-heavy nuclei drive deleptonization and simulations require the use of accurate reaction rates. Nuclei with neutron number near $N = 50$ , just above atomic number $Z = 28$ , play an important role, but rates used in astrophysical simulations rely primarily on a relatively simple single-state approximation. In order to improve the accuracy of astrophysical simulations, experimental data are needed to test the electron-capture rates and to guide the development of better theoretical models. This work presents the results of the $^{86}$ Kr( $t$ , $^{3}$ He+ $γ$ ) experiment at the NSCL, from which an upper limit for the Gamow-Teller strength up to an excitation energy in $^{86}$ Br of 5 MeV is extracted. The derived upper limit for the electron-capture rate on $^{86}$ Kr indicates that the rate estimated through the single-state approximation is too high and that rates based on Gamow-Teller strengths estimated in shell-model and QRPA calculations are more accurate. The QRPA calculations tested in this manner were used for estimating the electron capture rates for 78 isotopes near $N = 50$ and above $Z = 28$ . The impact of using these new electron-capture rates in simulations of supernovae instead of the rates based on the single-state approximation is investigated, indicating a significant reduction in the deleptonization that affects multi-messenger signals, such as the emission of neutrinos and gravitational waves.
↳ nucl-exastro-ph.HEastro-ph.SRnucl-thPRC(2019)·18 citations
09
Relativistic many body theory of the electric dipole moment of $^{129}$ Xe and its implications for probing new physics beyond the Standard Model
Akitada Sakurai🇯🇵 · B. K. Sahoo🇮🇳 · K. Asahi🇯🇵 · B. P. Das🇯🇵
We report the results of our theoretical studies of the time-reversal and parity violating electric dipole moment (EDM) of $^{129}$ Xe arising from the nuclear Schiff moment (NSM) and the electron-nucleus tensor-pseudotensor (T-PT) interaction based on the self-consistent and the normal relativistic coupled-cluster methods. The important many-body effects are highlighted and their contributions are explicitly presented. The uncertainties in the calculations of the correlation and relativistic effects are determined by estimating the contributions of the triples excitations, and the Breit interaction respectively, which together amount to about 0.7% for the NSM and 0.2% for the T-PT interactions. The results of our present work in combination with improved experimental limits for $^{129}$ Xe EDM in the future would tighten the constraints on the hadronic CP violating quantities, and this could provide important insights into new physics beyond the Standard Model of elementary particles.
↳ physics.atom-phhep-phnucl-thPRA(2019)·13 citations
10
Accelerating lattice quantum field theory calculations via interpolator optimization using NISQ-era quantum computing
A. Avkhadiev🇺🇸 · P. E. Shanahan🇺🇸 · R. D. Young🇦🇺
The only known way to study quantum field theories in non-perturbative regimes is using numerical calculations regulated on discrete space-time lattices. Such computations, however, are often faced with exponential signal-to-noise challenges that render key physics studies untenable even with next generation classical computing. Here, a method is presented by which the output of small-scale quantum computations on Noisy Intermediate-Scale Quantum era hardware can be used to accelerate larger-scale classical field theory calculations through the construction of optimized interpolating operators. The method is implemented and studied in the context of the 1+1-dimensional Schwinger model, a simple field theory which shares key features with the standard model of nuclear and particle physics.
↳ hep-lathep-phnucl-thPRL(2020)·41 citations
11
Event multiplicity, transverse momentum and energy dependence of charged particle production, and system thermodynamics in $pp$ collisions at the Large Hadron Collider
Rutuparna Rath🇮🇳 · Arvind Khuntia🇵🇱 · Raghunath Sahoo🇮🇳 · Jean Cleymans🇿🇦
In the present work, we study the recent collision energy and multiplicity dependence of the charged particle transverse momentum spectra as measured by the ALICE collaboration in $pp$ collisions at $s$ = 5.02 and 13 TeV using the non-extensive Tsallis distribution and the Boltzmann-Gibbs Blast Wave (BGBW) model. A thermodynamically consistent form of the Tsallis distribution is used to extract the kinetic freeze-out parameters from the transverse momentum spectra of charged particles at mid-rapidity. In addition, a comprehensive study of fitting range dependence of transverse momentum spectra on the freeze-out parameters is done using Tsallis statistics. The applicability of BGBW model is verified by fitting the transverse momentum spectra of the bulk part ( $\sim 2.5 GeV / c$ )for both 5.02 and 13 TeV energies and also in different multiplicity classes. The radial flow, $< β >$ is almost independent of collision energy and multiplicity whereas the behavior of kinetic freeze-out temperature significantly depends on multiplicity classes. It is found that the Tsallis distribution generally leads to a better description for the complete transverse momentum spectra whereas the BGBW model explains the bulk part of the system.
↳ hep-phhep-exnucl-exnucl-thJ.Phys.G(2020)·32 citations
12
Clustering of Four-Component Unitary Fermions
William G. Dawkins🇨🇦 · J. Carlson🇺🇸 · U. van Kolck🇫🇷 · Alexandros Gezerlis🇨🇦
Ab initio nuclear physics tackles the problem of strongly interacting four-component fermions. The same setting could foreseeably be probed experimentally in ultracold atomic systems, where two- and three-component experiments have led to major breakthroughs in recent years. Both due to the problem's inherent interest and as a pathway to nuclear physics, in this Letter we study four-component fermions at unitarity via the use of quantum Monte Carlo methods. We explore novel forms of the trial wave function and find one which leads to a ground state of the eight-particle system whose energy is almost equal to that of two four-particle systems. We investigate the clustering properties involved and also extrapolate to the zero-range limit. In addition to being experimentally testable, our results impact the prospects of developing nuclear physics as a perturbation around the unitary limit.
↳ cond-mat.quant-gasnucl-thphysics.atm-clusPRL(2020)·22 citations

Affiliations

first authorsco-authorsvia INSPIRE

Indirect Detection of Composite (Asymmetric) Dark Matter

Development and testing of an unstructured mesh method for whole plasma gyrokinetic simulations in realistic tokamak geometry

Constraints for stellar electron-capture rates on 86Kr via the 86Kr(t,3He+γ)86Br reaction and the implications for core-collapse supernovae

Relativistic many body theory of the electric dipole moment of 129Xe and its implications for probing new physics beyond the Standard Model

Accelerating lattice quantum field theory calculations via interpolator optimization using NISQ-era quantum computing

Event multiplicity, transverse momentum and energy dependence of charged particle production, and system thermodynamics in pp collisions at the Large Hadron Collider

Clustering of Four-Component Unitary Fermions

Affiliations

Constraints for stellar electron-capture rates on $^{86}$ Kr via the $^{86}$ Kr( $t$ , $^{3}$ He $+ γ$ ) $^{86}$ Br reaction and the implications for core-collapse supernovae

Relativistic many body theory of the electric dipole moment of $^{129}$ Xe and its implications for probing new physics beyond the Standard Model

Event multiplicity, transverse momentum and energy dependence of charged particle production, and system thermodynamics in $pp$ collisions at the Large Hadron Collider