Inferring type and scale of noncommutativity from the PTOLEMY experiment

If neutrinos are Dirac particles and their right-handed component can be copiously produced in the early universe, then they could influence a direct observation of the cosmic neutrino background, which, most likely, will come about with the recently proposed PTOLEMY experiment. For the production mechanism of right-handed neutrinos we use a state-of-the-art version of gauge field theory deformed by the spacetime noncommutativity, to disclose by it not only the decoupling temperature for the said neutrino component, but also the otherwise hidden coupling temperature. Considering two relevant processes, the plasmon decay and the neutrino elastic scattering, we study the interplay between the structure of the noncommutativity parameter $\theta^{\mu \nu}$ (type of noncommutativity) and the reheating temperature after inflation to obtain otherwise elusive upper bound on the scale of noncommutativity $\Lambda_{\rm NC}$. If PTOLEMY enhanced capture rate is due to spacetime noncommutativity, we verify that a nontrivial maximum upper bound on $\Lambda_{\rm NC}$ (a way below the Planck scale) emerges for a space-like $\theta^{\mu \nu}$ and sufficiently high reheating temperature.Comment: 6 pagees, 1 figure, version of article to be published in EPJ

Momentum-independent renormalization of the Schwinger-Dyson equation with an instantaneous-interaction kernel

We consider the problem of renormalization of the Schwinger-Dyson equation, encountered when the interquark interaction kernel is modeled by an instantaneous potential. More precisely, the Coulomb potential, needed for describing the short-distance part of the gluon exchange, leads to ultraviolet divergences in the Schwinger-Dyson equation. The standard prescription which has been used up till now to subtract these divergences, suffers from a serious conceptual problem: it is not momentum independent. In this work we propose a new and momentum-independent renormalization prescription, and take special care to preserve the correct chiral limit for light pseudoscalar mesons

Impulsno neovisna renormalizacija Schwinger–Dysonove jednadžbe s trenutnom interakcijom

We consider the problem of renormalization of the Schwinger-Dyson equation, encountered when the interquark interaction kernel is modeled by an instantaneous potential. More precisely, the Coulomb potential, needed for describing the short-distance part of the gluon exchange, leads to ultraviolet divergences in the Schwinger-Dyson equation. The standard prescription which has been used up till now to subtract these divergences, suffers from a serious conceptual problem: it is not momentum independent. In this work we propose a new and momentum-independent renormalization prescription, and take special care to preserve the correct chiral limit for light pseudoscalar mesons.Razmatramo problem koji se prilikom renormalizacije Schwinger–Dysonove jednadžbe susreće kada je jezgra medukvarkovske interakcije modelirana trenutnim potencijalom. Preciznije, Coulombov potencijal, potreban za opis gluonske izmjene na malim udaljenostima izmedu kvarkova, dovodi do ultraljubičastih divergencija u Schwinger–Dysonovoj jednadžbi. Standardna postavka koja se dosad upotrebljavala za uklanjanje tih divergencija ima ozbiljan konceptualan problem: ona nije impulsno neovisna. U ovom radu predlažemo jednu novu impulsno neovisnu postavku, pri čemu posebno pazimo da bude očuvan ispravan kiralni limes za lagane pseudoskalarne mezone

Impulsno neovisna renormalizacija Schwinger–Dysonove jednadžbe s trenutnom interakcijom

We consider the problem of renormalization of the Schwinger-Dyson equation, encountered when the interquark interaction kernel is modeled by an instantaneous potential. More precisely, the Coulomb potential, needed for describing the short-distance part of the gluon exchange, leads to ultraviolet divergences in the Schwinger-Dyson equation. The standard prescription which has been used up till now to subtract these divergences, suffers from a serious conceptual problem: it is not momentum independent. In this work we propose a new and momentum-independent renormalization prescription, and take special care to preserve the correct chiral limit for light pseudoscalar mesons.Razmatramo problem koji se prilikom renormalizacije Schwinger–Dysonove jednadžbe susreće kada je jezgra medukvarkovske interakcije modelirana trenutnim potencijalom. Preciznije, Coulombov potencijal, potreban za opis gluonske izmjene na malim udaljenostima izmedu kvarkova, dovodi do ultraljubičastih divergencija u Schwinger–Dysonovoj jednadžbi. Standardna postavka koja se dosad upotrebljavala za uklanjanje tih divergencija ima ozbiljan konceptualan problem: ona nije impulsno neovisna. U ovom radu predlažemo jednu novu impulsno neovisnu postavku, pri čemu posebno pazimo da bude očuvan ispravan kiralni limes za lagane pseudoskalarne mezone

Constraining interacting dark energy models with flux destabilization

A destabilization in the transfer energy flux from the vacuum to radiation, for two vacuum decay laws relevant to the dark energy problem, is analyzed using the Landau-Lifshitz fluctuation hydrodynamic theory. Assuming thermal (or near thermal) equilibrium between the vacuum and radiation, at the earliest epoch of the Universe expansion, we show that the law due to renormalization-group running of the cosmological constant term, with parameters chosen not to spoil the primordial nucleosynthesis scenario, does soon drive the flux to fluctuate beyond its statistical average value thereby distorting the cosmic background radiation spectrum beyond observational limits. While the law coming from the saturated holographic dark energy does not lead the flux to wildly fluctuate, a more realistic non--saturated form shows again such anomalous behavior.Comment: 12 pages, minor correction, to appear in Physics Letters