Search results for "Number"
showing 10 items of 3939 documents
Strange tribaryons
2006
We use two-body potentials derived from a constituent quark cluster model to analyze the bound-state problem of the $\Sigma NN$ system. The observables of the two-body subsystems, $NN$ and $\Sigma N$, are well reproduced. We do not find $\Sigma NN$ bound states, but there are two attractive channels with a resonance close above the three-body threshold. These channels are the $(I,J)=(1,1/2)$ and $(0,1/2)$, their quantum numbers, widths and energy ordering consistent with the recently measured strange tribaryons from the $^{4}{\rm He}(K_{{\rm stopped}}^{-},N)$ reactions in the KEK PS E471 experiment.
Geotomography with solar and supernova neutrinos
2005
We show how by studying the Earth matter effect on oscillations of solar and supernova neutrinos inside the Earth one can in principle reconstruct the electron number density profile of the Earth. A direct inversion of the oscillation problem is possible due to the existence of a very simple analytic formula for the Earth matter effect on oscillations of solar and supernova neutrinos. From the point of view of the Earth tomography, these oscillations have a number of advantages over the oscillations of the accelerator or atmospheric neutrinos, which stem from the fact that solar and supernova neutrinos are coming to the Earth as mass eigenstates rather than flavour eigenstates. In particula…
Are solar neutrino oscillations robust?
2004
The robustness of the large mixing angle (LMA) oscillation (OSC) interpretation of the solar neutrino data is considered in a more general framework where non-standard neutrino interactions (NSI) are present. Such interactions may be regarded as a generic feature of models of neutrino mass. The 766.3 ton-yr data sample of the KamLAND collaboration are included in the analysis, paying attention to the background from the reaction ^13C(\alpha,n) ^16O. Similarly, the latest solar neutrino fluxes from the SNO collaboration are included. In addition to the solution which holds in the absence of NSI (LMA-I) there is a 'dark-side' solution (LMA-D) with sin^2 theta_Sol = 0.70, essentially degenerat…
Multiquark description of theDsJ(2860)andDsJ(2700)
2009
Within a theoretical framework that accounts for all open-charm mesons, including the ${D}_{0}^{*}(2308)$, the ${D}_{sJ}^{*}(2317)$, and the ${D}_{sJ}(2460)$, we analyze the structure and explore possible quantum number assignments for the ${D}_{sJ}(2860)$ and the ${D}_{sJ}(2700)$ mesons reported by BABAR and Belle Collaborations. The open-charm sector is properly described if considered as a combination of conventional quark-antiquark states and four-quark components. All negative parity and ${2}^{+}$ states can be understood in terms only of $q\overline{q}$ components, however the description of the ${0}^{+}$ and ${1}^{+}$ mesons is improved whenever the mixing between two- and four-quark…
Single-photon Z decays and small neutrino masses
1996
We discuss some rare Z decay signatures associated with extensions of the Standard Model with spontaneous lepton number violation at the electroweak scale. We show that single-photon Z decays such as $Z \to \gamma H$ and $Z \to \gamma J J$ where H is a CP-even Higgs boson and J denotes the associated CP-odd Majoron may occur with branching ratios accessible to LEP sensitivities, even though the corresponding neutrino masses can be very small, as required in order to explain the deficit of solar neutrinos.
Extended Black Box Theorem for Lepton Number and Flavor Violating processes
2006
We revisit the well known "Black Box" theorem establishing a fundamental relation between the amplitude of neutrinoless double beta decay and the effective Majorana neutrino mass. We extend this theorem to the general case of arbitrary lepton number and lepton flavor violating (LFNV) processes and to the three generation Majorana neutrino mass matrix. We demonstrate the existence of a general set of one-to-one correspondence relations between the effective operators generating these processes, and elements of the neutrino mass matrix, such that if one of these two quantities vanishes the other is guaranteed to vanish as well, and moreover, if one of these quantities is non-zero the other is…
Neutrino mass and invisible Higgs decays at the LHC
2015
The discovery of the Higgs boson suggests that also neutrinos get their mass from spontaneous symmetry breaking. In the simplest ungauged lepton number scheme, the Standard Model (SM) Higgs has now two other partners: a massive CP-even, as well as the massless Nambu-Goldstone boson, called majoron. For weak-scale breaking of lepton number the invisible decays of the CP- even Higgs bosons to the majoron lead to potentially copious sources of events with large missing energy. Using LHC results we study how the constraints on invisible decays of the Higgs boson restrict the relevant parameters, substantially extending those previously derived from LEP and shedding light on spontaneous lepton n…
17 keV neutrino in a singlet-triplet majoron model
1991
Abstract We investigate the possibility of a cosmologically safe 17 keV neutrino which may have been observed in the decays of tritium, S 35 , and C 14 within a singlet-triplet majoron model. Consideration of the leptonic decay of K + and X rays associated with the radiative decay of massive relic neutrinos severely constrains the scale of the spontaneous lepton number violation. It is argued that the mass density of relic 17 keV neutrinos is constrained as Ω v ⩽ 0.05 h −1 (0.01/ sin 2 θ ) in view of the observed diffuse X ray background.
On the nature of the fourth generation neutrino and its implications
2012
We consider the neutrino sector of a Standard Model with four generations. While the three light neutrinos can obtain their masses from a variety of mechanisms with or without new neutral fermions, fourth-generation neutrinos need at least one new relatively light right-handed neutrino. If lepton number is not conserved this neutrino must have a Majorana mass term whose size depends on the underlying mechanism for lepton number violation. Majorana masses for the fourth generation neutrinos induce relative large two-loop contributions to the light neutrino masses which could be even larger than the cosmological bounds. This sets strong limits on the mass parameters and mixings of the fourth …
Pentaquark from QCD sum rules: consequences of the diquark approach
2006
In this work we investigate the consequences of the Jaffe and Wilczek diquark model in the framework of QCD sum rules. An analysis of the Theta^+(1540) as (ud)^2\bar{s} state shows that the mass of the pentaquark is compatible with the experimentally measured value. The mass difference between the Theta^+ and the pentaquark with the quantum numbers of the nucleon amounts to 70 MeV and is consistent with the interpretation of the N(1440) as a pentaquark.