Nuclear Theory·nucl-th

Thursday·April 2, 2015

10 papers—4 primary·6 cross-listed

05
Quantum field theory in a magnetic field: From quantum chromodynamics to graphene and Dirac semimetals
Vladimir A. Miransky🇨🇦 · Igor A. Shovkovy🇺🇸
A range of quantum field theoretical phenomena driven by external magnetic fields and their applications in relativistic systems and quasirelativistic condensed matter ones, such as graphene and Dirac/Weyl semimetals, are reviewed. We start by introducing the underlying physics of the magnetic catalysis. The dimensional reduction of the low-energy dynamics of relativistic fermions in an external magnetic field is explained and its role in catalyzing spontaneous symmetry breaking is emphasized. The general theoretical consideration is supplemented by the analysis of the magnetic catalysis in quantum electrodynamics, chromodynamics and quasirelativistic models relevant for condensed matter physics. By generalizing the ideas of the magnetic catalysis to the case of nonzero density and temperature, we argue that other interesting phenomena take place. The chiral magnetic and chiral separation effects are perhaps the most interesting among them. In addition to the general discussion of the physics underlying chiral magnetic and separation effects, we also review their possible phenomenological implications in heavy-ion collisions and compact stars. We also discuss the application of the magnetic catalysis ideas for the description of the quantum Hall effect in monolayer and bilayer graphene, and conclude that the generalized magnetic catalysis, including both the magnetic catalysis condensates and the quantum Hall ferromagnetic ones, lies at the basis of this phenomenon. We also consider how an external magnetic field affects the underlying physics in a class of three-dimensional quasirelativistic condensed matter systems, Dirac semimetals. While at sufficiently low temperatures and zero density of charge carriers, such semimetals are expected to reveal the regime of the magnetic catalysis, the regime of Weyl semimetals with chiral asymmetry is realized at nonzero density...
↳ hep-phcond-mat.str-elhep-thnucl-thPhys.Rept.(2015)·708 citations
06
Precise determination of $_{Λ}^{12}$ C level structure by $γ$ -ray spectroscopy
K. Hosomi🇯🇵 · T. Ma🇯🇵 · S. Ajimura🇯🇵 · K. Aoki🇯🇵 · S. Dairaku🇯🇵 · Y. Y. Fu🇨🇳 · H. Fujioka🇯🇵 · K. Futatsukawa🇯🇵 · W. Imoto🇯🇵 · Y. Kakiguchi🇯🇵 · M. Kawai🇯🇵 · S. Kinoshita🇯🇵 and 21 other authors
Level structure of the $_{Λ}^{12}$ C hypernucleus was precisely determined by means of $γ$ -ray spectroscopy. We identified four $γ$ -ray transitions via the $^{12}$ C $(π^{+}, K^{+} γ)$ reaction using a germanium detector array, Hyperball2. The spacing of the ground-state doublet $(2_{1}^{-}, 1_{1}^{-})$ was measured to be $161.5 \pm 0.3 (stat) \pm 0.3 (syst)$ \,keV from the direct $M 1$ transition. Excitation energies of the $1_{2}^{-}$ and $1_{3}^{-}$ states were measured to be $2832 \pm 3 \pm 4$ \,keV and $6050 \pm 8 \pm 7$ \,keV, respectively. The obtained level energies provide definitive references for the reaction spectroscopy of $Λ$ hypernuclei.
↳ nucl-exnucl-thPTEP(2015)·14 citations
07
Gluon Propagation in Curved Space
Su Kyeong Lee🇰🇷 · Eun-Joo Kim🇰🇷 · Jong Bum Choi🇰🇷
In quantum chromodynamics (QCD), the vacuum structures are taken to be formed by nonperturbative interactions between gluons. The contributions of gluonic interactions can be parametrized by gluon condensates and especially the dimension-2 condensate $⟨ A_{μ}^{2} ⟩$ can be used to generalize the $θ$ vacuum. In the generalized picture, each gauge fixed slice forms a curved surface around a hadron and other strongly interacting objects, and the propagation of a gluon has to be considered on this curved surface. The gluon propagator turns out to be massive due to the curvature of the gauge fixed surface implementing the possibility that the massless gauge bosons might provide the majority of the hadronic mass and even behave as dark matter in cosmological scales.
↳ hep-thhep-phnucl-thJ.Korean Phys.Soc.(2015)·1 citation
08
A perturbative description of the deconfinement transition in Yang-Mills theories
Julien Serreau🇫🇷
We investigate the deconfinement transition of static quarks in SU(N) Yang-Mills theories using a perturbative approach based on a massive extension of the Landau-DeWitt gauge-fixed action, where the gluon mass term is related to the issue of Gribov ambiguities. A leading-order, one-loop calculation of the effective potential for the Polyakov loop produces a deconfinement transition of second order for the SU(2) theory and of first order for SU(3) with transition temperatures in qualitative agreement with known values. We also report on the results of a two-loop calculation of the critical temperature and of thermodynamical quantities in the SU(2) case.
↳ hep-thhep-lathep-phnucl-thPoS(2015)·5 citations
09
Medium effects on the relaxation of dissipative flows in a hot pion gas
Sukanya Mitra🇮🇳 · Utsab Gangopadhyaya🇮🇳 · Sourav Sarkar🇮🇳
The relaxation times over which dissipative fluxes restore their steady state values have been evaluated for a pion gas using the 14-moment method. The effect of the medium has been implemented through a temperature dependent pi-pi cross-section in the collision integral which is obtained by including one-loop self-energies in the propagators of the exchanged rho and sigma mesons. To account for chemical freeze out in heavy ion collisions, a temperature dependent pion chemical potential has been introduced in the distribution function. The temperature dependence of the relaxation times for shear and bulk viscous flows as well as the heat flow is significantly affected.
↳ hep-phnucl-thPRD(2015)·22 citations
10
Electric dipole moment of $^{225}$ Ra due to P- and T-violating weak interactions
Yashpal Singh🇮🇳 · B. K. Sahoo🇮🇳
We report rigorous calculations of electric dipole moment (EDM) in $^{225}$ Ra due to parity and time-reversal violating tensor-pseudotensor (T-PT) and nuclear Schiff moment (NSM) interactions between the electrons and nucleus by employing the relativistic all order coupled-cluster (RCC) methods at various levels of approximation. The most accurate EDM ( $d_{A}$ ) results are obtained as $d_{A} = - 10.04 \times 1 0^{- 20} C_{T} < σ_{n} > ∣ e ∣ c m$ and $d_{A}^{N S M} = - 6.79 \times 1 0^{- 17} S (∣ e ∣ f m^{3})^{- 1} ∣ e ∣ c m$ with $C_{T}$ and $S$ are the T-PT coupling constant and NSM respectively. Due to exhaustive treatment of the electron correlation effects in these calculations, the EDM results for the corresponding T-PT and NSM interactions reduce by about 45\% and 23\%, respectively, from the previously known values. Nonetheless they are still found to be 2-3 times larger than the $^{199}$ Hg results. Validity of the RCC results are countenanced by comparing our calculations at the zeroth order Dirac-Fock method and all order random-phase approximation with the other groups. In view of the current experimental progress in the $^{225}$ Ra EDM measurement, our high accuracy calculations are very useful to yield limits on $C_{T}$ and $S$ in this atom. Thusly, it is possible to realize more accurate limits on the electron-quark T-PT interaction and $θ_{QC D}$ parameter of particle physics in future.
↳ physics.atom-phhep-phnucl-thPRA(2015)·22 citations

Affiliations

first authorsco-authorsvia INSPIRE

Quantum field theory in a magnetic field: From quantum chromodynamics to graphene and Dirac semimetals

Precise determination of Λ12​C level structure by γ-ray spectroscopy

Gluon Propagation in Curved Space

A perturbative description of the deconfinement transition in Yang-Mills theories

Medium effects on the relaxation of dissipative flows in a hot pion gas

Electric dipole moment of 225Ra due to P- and T-violating weak interactions

Affiliations

Precise determination of $_{Λ}^{12}$ C level structure by $γ$ -ray spectroscopy

Electric dipole moment of $^{225}$ Ra due to P- and T-violating weak interactions