Search results for "lepton number"
showing 10 items of 106 documents
Majoron emission in muon and tau decays revisited
2009
9 pages, 4 figures.-- ISI article identifier:000264762400078.-- ArXiv pre-print avaible at: http://arxiv.org/abs/0902.0525
Neutrino Masses and Lepton Flavour Violation in Thick Brane Scenarios
2001
We address the issue of lepton flavour violation and neutrino masses in the ``fat-brane'' paradigm, where flavour changing processes are suppressed by localising different fermion field wave-functions at different positions (in the extra dimensions) in a thick brane. We study the consequences of suppressing lepton number violating charged lepton decays within this scenario for lepton masses and mixing angles. In particular, we find that charged lepton mass matrices are constrained to be quasi-diagonal. We further consider whether the same paradigm can be used to naturally explain small Dirac neutrino masses by considering the existence of three right-handed neutrinos in the brane, and discu…
Search for lepton-number violatingB+→X−ℓ+ℓ′+decays
2014
We report on a search for eleven lepton-number violating processes B^+→X^−l^+l'^+ with X^−=K^−, π^−, ρ^−, K^(*−), or D^− and l^+/l'^+=e^+ or μ^+, using a sample of 471±3 million BB events collected with the BABAR detector at the PEP-II e^+e^− collider at the SLAC National Accelerator Laboratory. We find no evidence for any of these modes and place 90% confidence level upper limits on their branching fractions in the range (1.5–26)×10_(−7).
Searches for the baryon- and lepton-number violating decaysB0→Λc+l−,B−→Λl−, andB−→Λ¯l−
2011
Searches for $B$ mesons decaying to final states containing a baryon and a lepton are performed, where the baryon is either $\Lambda_c$ or $\Lambda$ and the lepton is a muon or an electron. These decays violate both baryon and lepton number and would be a signature of physics beyond the standard model. No significant signal is observed in any of the decay modes, and upper limits in the range $(3.2-520) \times 10^{-8}$ are set on the branching fractions at the 90% confidence level.
Neutrinoless double beta decay and lepton number violation at the lhc
2013
10.1103/PhysRevD.88.011901
A general parametrization for the long-range part of neutrinoless double beta decay
1997
Double beta decay has been proven to be a powerful tool to constrain $B-L$ violating physics beyond the standard model. We present a representation for the long-range part of the general $0\nu\beta\beta$ decay rate allowed by Lorentz-invariance. Combined with the short range part this general parametrization in terms of effective $B-L$ violating couplings will provide the $0\nu\beta\beta$ limits on arbitrary lepton number violating theories.
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.