Search results for "weak coupling"
showing 6 items of 6 documents
Quantum Nanoplasmonic : from dressed atom picture to superradiance
2019
Controlling quantum emitters (atoms, molecules, quantum dots, etc.), light, and its interactions is a key issue for implementing devices for information optical processing at the quantum level. For example, controlling dynamics of emitters coupled to a high-Q cavity can be achieved through cavity quantum electrodynamics (cQED). Plasmonic structures hybrid system are of growing interest in the quantum control at the nanoscale because of their capability to confine light beyond the diffraction limit. However, its application appears notoriously limited in practical situations due to the intrinsic presence of numerous and lossy modes, which complicates the description and the interpretation of…
Spin-dipole nuclear matrix elements for double beta decays and astro-neutrinos
2014
Spin-dipole (SD) nuclear matrix elements (NMEs) M±(SD2) for unique first forbidden β±2−→0+ ground-state-to-ground-state transitions are studied by using effective microscopic two-nucleon interactions in realistic single-particle model spaces. The observed values of the NMEs Mexp±(SD2) are compared with the values of the single-quasiparticle NMEs Mqp±(SD2) without nucleon spin–isospin (στ) correlation and the QRPA NMEs MQRPA±(SD2) with the στ correlation. The observed SD matrix elements are found to be reduced by the factor k≈0.2 with respect to Mqp±(SD2) and by the factor kNM≈0.5 with respect to MQRPA±(SD2). We then infer that the SD NME is reduced considerably partly by the nucleon στ corr…
Quantum and classical dynamics of heavy quarks in a quark-gluon plasma
2018
We derive equations for the time evolution of the reduced density matrix of a collection of heavy quarks and antiquarks immersed in a quark gluon plasma. These equations, in their original form, rely on two approximations: the weak coupling between the heavy quarks and the plasma, the fast response of the plasma to the perturbation caused by the heavy quarks. An additional semi-classical approximation is performed. This allows us to recover results previously obtained for the abelian plasma using the influence functional formalism. In the case of QCD, specific features of the color dynamics make the implementation of the semi-classical approximation more involved. We explore two approximate…
Determination of the non-abelian Debye screening mass using classical chromodynamics
2014
Tässä työssä tutkitaan gluonin Debye-massaa, ja sen aika- ja miehityslukudis- tribuutioriippuvuutta käyttäen klassista väridynamiikkaa kahdessa paikkaulot- tuvuudessa. Työssä tutkitaan myös ominaista liikemääräskaalaa ja miehitys- lukudistribuutioita. Gluonin Debye-massa määritetään sovittamalla suora glu- onien dispersiorelaatioon pienellä liikemäärällä. Tuloksia verrataan termisestä kenttäteoriasta johdetun kaavan ennusteisiin. Aluksi tutustutaan raskasionifysiikkaan liittyvään viitekehykseen. Tämän jälkeen kerrataan nopeasti klassinen Yang-Mills teoria jatkumossa ja hilalla. Käydään läpi Fourier kiihdytetty Coulombin mitan kiinnitysmenetelmä yk- sityiskohtaisesti jatkumossa ja hilalla. T…
Forbidden nonunique β decays and effective values of weak coupling constants
2016
Forbidden nonunique β decays feature shape functions that are complicated combinations of different nuclear matrix elements and phase-space factors. Furthermore, they depend in a very nontrivial way on the values of the weak coupling constants, gV for the vector part and gA for the axial-vector part. In this work we include also the usually omitted second-order terms in the shape functions to see their effect on the computed decay half-lives and electron spectra (β spectra). As examples we study the fourth-forbidden nonunique ground-state-to-ground-state β− decay branches of 113Cd and 115In using the microscopic quasiparticle-phonon model and the nuclear shell model. A striking new feature …
Forbidden nonuniqueβdecays and effective values of weak coupling constants
2016
Forbidden nonunique $\ensuremath{\beta}$ decays feature shape functions that are complicated combinations of different nuclear matrix elements and phase-space factors. Furthermore, they depend in a very nontrivial way on the values of the weak coupling constants, ${g}_{\mathrm{V}}$ for the vector part and ${g}_{\mathrm{A}}$ for the axial-vector part. In this work we include also the usually omitted second-order terms in the shape functions to see their effect on the computed decay half-lives and electron spectra ($\ensuremath{\beta}$ spectra). As examples we study the fourth-forbidden nonunique ground-state-to-ground-state ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay branches of $^{113}\ma…