Search results for "Model theory"
showing 10 items of 681 documents
(g−2)e,μ in an extended inverse type-III seesaw model
2021
There has been a longstanding discrepancy between the experimental measurements of the electron and muon anomalous magnetic moments and their predicted values in the Standard Model. This is particularly relevant in the case of the muon $g\ensuremath{-}2$, which has attracted a remarkable interest in the community after the long-awaited announcement of the first results by the Muon $g\ensuremath{-}2$ collaboration at Fermilab, which confirms a previous measurement by the E821 experiment at Brookhaven and enlarges the statistical significance of the discrepancy, now at $4.2\ensuremath{\sigma}$. In this paper we consider an extension of the inverse type-III seesaw with a pair of vectorlike lep…
A CMB search for the neutrino mass mechanism and its relation to the Hubble tension
2020
AbstractThe majoron, a pseudo-Goldstone boson arising from the spontaneous breaking of global lepton number, is a generic feature of many models intended to explain the origin of the small neutrino masses. In this work, we investigate potential imprints in the cosmic microwave background (CMB) arising from massive majorons, should they thermalize with neutrinos after Big Bang Nucleosynthesis via inverse neutrino decays. We show that measurements of the CMB are currently sensitive to neutrino-majoron couplings as small as $$\lambda \sim 10^{-13}$$λ∼10-13, which if interpreted in the context of the type-I seesaw mechanism correspond to a lepton number symmetry breaking scale $$v_L \sim {\math…
Charged Higgs signals in tt¯H searches
2017
New scalars from an extended Higgs sector could have weak scale masses and still have escaped detection. In a type I two Higgs doublet model, for instance, even the charged Higgs can be lighter than the top quark. Because electroweak production of these scalars is modest, the greatest opportunity for their detection might come from rare top decays. For mass hierarchies of the type ${m}_{t}g{m}_{{H}^{+}}g{m}_{{A}^{0},{H}^{0}}$, the natural signal can arise from top quark pair production, followed by the decay chain $t\ensuremath{\rightarrow}b{H}^{+}$, ${H}^{+}\ensuremath{\rightarrow}{W}^{+(*)}{\ensuremath{\phi}}^{0}$, ${\ensuremath{\phi}}^{0}\ensuremath{\rightarrow}b\overline{b},{\ensuremath…
On Weyl-electric and Weyl-magnetic spacetimes
2002
The concepts of purely electric and purely magnetic Weyl tensors are extended and the intrinsic characterization of the new wider classes is given. The solutions v to the equations W(v; v) = 0 or *W(v; v) = 0 are determined for every Petrov type, and the new electric or magnetic type I cases are studied in more detail.
Rainich theory for type D aligned Einstein–Maxwell solutions
2007
The original Rainich theory for the non-null Einstein-Maxwell solutions consists of a set of algebraic conditions and the Rainich (differential) equation. We show here that the subclass of type D aligned solutions can be characterized just by algebraic restrictions.
On the Weyl transverse frames in type I spacetimes
2004
We apply a covariant and generic procedure to obtain explicit expressions of the transverse frames that a type I spacetime admits in terms of an arbitrary initial frame. We also present a simple and general algorithm to obtain the Weyl scalars $\Psi_2^T$, $\Psi_0^T$ and $\Psi_4^T$ associated with these transverse frames. In both cases it is only necessary to choose a particular root of a cubic expression.
Hydrodynamic synchronization of pairs of puller type magnetotactic bacteria in a high frequency rotating magnetic field.
2019
Ensembles of magnetotactic bacteria are known to interact hydrodynamically and form swarms under the influence of external magnetic fields. We describe the synchronization of puller type magnetotactic bacteria in a rotating magnetic field by representing the bacteria as hydrodynamic force dipoles. Numerical simulations show that at moderate values of the hydrodynamic interaction parameter large ensembles of asynchronously rotating bacteria randomly eject propagating doublets of synchronized bacteria. We quantitatively analyze the dynamics of the doublets and show that an important role in the formation of these propagating structures is played by the parameters characterizing the possible t…
Semitoroidal detector configuration for large (well-type) Ge(Li) detectors
1972
Abstract A “semitoroidal” detector configuration intended for making large Ge(Li) detectors with approximately homogeneous electric fields is described in detail. Test measurements have been carried out with a relatively small semitoroidal detector. The performance of the semitoroidal detector having a volume of more than 150 cm 3 is discussed.
Mass of astrophysically relevantCl31and the breakdown of the isobaric multiplet mass equation
2016
The mass of $^{31}\mathrm{Cl}$ has been measured with the JYFLTRAP double-Penning-trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility. The determined mass-excess value, $\ensuremath{-}7034.7(34)$ keV, is 15 times more precise than in the Atomic Mass Evaluation 2012. The quadratic form of the isobaric multiplet mass equation for the $T=3/2$ quartet at $A=31$ fails $({\ensuremath{\chi}}_{n}^{2}=11.6)$ and a nonzero cubic term, $d=\ensuremath{-}3.5(11)$ keV, is obtained when the new mass value is adopted. $^{31}\mathrm{Cl}$ has been found to be less proton-bound, with a proton separation energy of ${S}_{p}=264.6(34)$ keV. Energies for the excited states in $^{31…
Oscillatory Solutions of Boundary Value Problems
2016
We consider boundary value problems of the form $$\displaystyle\begin{array}{rcl} & x'' = f(t,x,x'), & {}\\ & x(a) = A,\quad x(b) = B,& {}\\ \end{array}$$ assuming that f is continuous together with f x and fx′. We study also equations in a quasi-linear form $$\displaystyle{x'' + p(t)x' + q(t)x = F(t,x,x').}$$ Introducing types of solutions of boundary value problems as an oscillatory type of the respective equation of variations, we show that for a solution of definite type, the problem can be reformulated in a quasi-linear form. Resonant problems are considered separately. Any resonant problem that has no solutions of indefinite type is in fact nonresonant. The ways of how to detect solut…