Nuclear Theory·nucl-th

Wednesday·July 10, 2019

10 papers—6 primary·4 cross-listed

07
Charged-lepton-flavor violation in $∣Δ S ∣ = 1$ hyperon decays
Xiao-Gang He🇨🇳 · Jusak Tandean🇹🇼 · German Valencia🇦🇺
Studies of lepton-flavor violation in strangeness-changing ( $∣Δ S ∣ = 1$ ) transitions have a~long tradition in the kaon sector where they provide some of the strongest limits on physics beyond the standard model. Recent hints of violation of lepton-flavor universality in $B$ -meson decays have revived interest in lepton-flavor violation as the two phenomena appear simultaneously in many extensions of the standard model. At the same time, the LHCb experiment has produced new results for the hyperon process $Σ^{+} \to p μ^{+} μ^{-}$ and may be in a position to study other rare hyperon decay modes. With this in mind, we investigate $∣Δ S ∣ = 1$ hyperon decays into different-flavor lepton pairs $e^{\pm} μ^{\mp}$ in a model-independent manner and contrast the coverage of parameter space that can be achieved with what is known from kaon modes. We include a comparison with selected two-body leptonic decays of charged mesons, with $K \to π ν ν ˉ$ modes, with $μ \to e$ conversion, and with lepton-flavor violating decays of other neutral mesons, all of which constrain the same parameter space in a complementary~way.
↳ hep-phhep-exnucl-thJHEP(2019)·10 citations
08
Linearly polarized gluons at next-to-next-to leading order and the Higgs transverse momentum distribution
Daniel Gutierrez-Reyes🇪🇸 · Sergio Leal-Gomez🇪🇸 · Ignazio Scimemi🇪🇸 · Alexey Vladimirov🇩🇪
We calculate the small-b (or large-qT) matching of transverse momentum dependent (TMD) distribution for linearly polarized gluons to the integrated gluon distributions at the next-to-next-to-leading order (NNLO). This is the last missing part for the complete NNLO prediction of the Higgs spectrum within TMD factorization. We discuss the numerical impact of the correction so derived to the qT-differential cross-section for Higgs boson production and to the positivity bound for linearly polarized gluon transverse momentum distribution.
↳ hep-phhep-exhep-latnucl-ex+1JHEP(2019)·79 citations
09
Charged pion condensation and duality in dense and hot chirally and isospin asymmetric quark matter in the framework of NJL $_{2}$ model
T. G. Khunjua🇷🇺 · K. G. Klimenko🇷🇺 · R. N. Zhokhov🇷🇺
In this paper we investigate in the large- $N_{c}$ limit ( $N_{c}$ is the number of colored quarks) the phase structure of a massless (1+1)-dimensional quark model with four-quark interaction and in the presence of baryon ( $μ_{B}$ ), isospin ( $μ_{I}$ ) and chiral isospin ( $μ_{I 5}$ ) chemical potentials as well as at nonzero temperature. It is established that chiral isospin chemical potential leads to the generation of charged pion condensation (PC) in dense (nonzero baryon density) and chiral asymmetric quark matter for a wide range of isospin densities. It is shown that there exists a duality correspondence between the chiral symmetry breaking and the charged PC phenomena at any values of temperature even for very hot quark gluon plasma. Moreover, it is shown that charged PC phase with nonzero baryon density can be induced in the model at comparatively high temperatures. This opens up new possible physical systems, where it can be of importance, such as heavy ion collisions, just born neutron stars (proto-neutron stars), supernovas as well as neutron star mergers.
↳ hep-phhep-thnucl-thPRD(2019)·36 citations
10
Bulk viscosity of baryonic matter with trapped neutrinos
Mark Alford🇺🇸 · Arus Harutyunyan🇦🇲 · Armen Sedrakian🇩🇪
We study bulk viscosity arising from weak current Urca processes in dense baryonic matter at and beyond nuclear saturation density. We consider the temperature regime where neutrinos are trapped and therefore have nonzero chemical potential. We model the nuclear matter in a relativistic density functional approach, taking into account the trapped neutrino component. We find that the resonant maximum of the bulk viscosity would occur at or below the neutrino trapping temperature, so in the neutrino trapped regime the bulk viscosity decreases with temperature as $T^{- 2}$ , this decrease being interrupted by a drop to zero at a special temperature where the proton fraction becomes density-independent and the material scale-invariant. The bulk viscosity is larger for matter with lower lepton fraction, i.e., larger isospin asymmetry. We find that bulk viscosity in the neutrino-trapped regime is smaller by several orders of magnitude than in the neutrino-transparent regime, which implies that bulk viscosity in neutrino-trapped matter is probably not strong enough to affect significantly the evolution of neutron star mergers. This also implies weak damping of gravitational waves emitted by the oscillations of the postmerger remnant in the high-temperature, neutrino-trapped phase of evolution.
↳ astro-ph.HEastro-ph.SRnucl-thPRD(2019)·79 citations

Affiliations

first authorsco-authorsvia INSPIRE

Charged-lepton-flavor violation in ∣ΔS∣=1 hyperon decays

Linearly polarized gluons at next-to-next-to leading order and the Higgs transverse momentum distribution

Charged pion condensation and duality in dense and hot chirally and isospin asymmetric quark matter in the framework of NJL2​ model

Bulk viscosity of baryonic matter with trapped neutrinos

Affiliations

Charged-lepton-flavor violation in $∣Δ S ∣ = 1$ hyperon decays

Charged pion condensation and duality in dense and hot chirally and isospin asymmetric quark matter in the framework of NJL $_{2}$ model