相关论文: A supersymmetric solution to the KARMEN time anoma…
The KARMEN experiment observes a time anomaly in events induced by pion decay at rest. This anomaly can be ascribed to the production of a new weakly interacting particle X with mass m_X\sim 34 MeV. We show that a recently proposed…
We consider the hypothesis that the recently reported anomaly in the time structure of signals in the KARMEN experiment is due to the production of a light photino (or Zino) which decays radiatively due to violation of $R$-parity. Such a…
A recently reported anomaly in the time structure of signals in the KARMEN neutrino detector suggests the decay of a new particle $x$, produced in $\pi^+ \to \mu^+ x$ with mass $m_x=33.9$ MeV. We discuss the constraints and difficulties in…
If a light gaugino sector exists in the supersymmetric standard model then the mass of lightest neutralino may be of the order of 1 GeV or less. As a consequence of neutral flavor violation in supersymmetric theories $B_s$-meson may decay…
The Karmen anomaly can be interpreted as being due to a heavy neutrino of mass around 137 MeV produced in $\pi_{e 2}$ decays. This interpretation is consistent with the present limits on the couplings of such an object.
In supersymmetric extensions of the Standard Model, the lightest neutralino, the gravitino, and the axino can appear as the lightest supersymmetric particle and as such provide a compelling explanation of the non-baryonic dark matter in our…
I address the question of whether supersymmetry provides a viable candidate for the dark matter in the Universe. I review the properties of the lightest neutralino as a candidate for solving the dark matter problem. I discuss the…
In constrained minimal supersymmetry the lightest neutralino of bino-type is the only neutral candidate for dark matter. As a result, one is typically able to restrict all the supersymmetric mass spectra below roughly 1-2\tev\ {\em without}…
We have searched for the pion decay pi^+ --> mu^+ X, where X is a neutral particle of mass 33.905 MeV. This process was suggested by the KARMEN Collaboration to explain an anomaly in their observed time distribution of neutrino induced…
An anomaly in time distribution of neutrinos from the ISIS pulsed beam stop source observed by the KARMEN collaboration is discussed. We show that the anomaly can be interpreted as a superposition of two exponentials, both having time…
Motivated by the anomaly in the KARMEN experiment, we study new possibilities for brane-world models of neutrino masses. We show that the KARMEN anomaly can be understood in the context of a six-dimensional brane-world model. The…
We show that for gaugino mediated supersymmetry breaking the gravitino mass is bounded from below. For a size of the compact dimensions of order the unification scale and a cutoff given by the higher-dimensional Planck mass, we find…
We examine the allowed mass range of the lightest neutralino within the Minimal Non--minimal Supersymmetric Standard Model. Being absolutely stable if R-parity is conserved this lightest neutralino is a candidate for the dark matter of the…
Bilinear R-parity violating supersymmetric model is a viable model which can explain the smallness of neutrino masses and the mixing pattern in the lepton sector. In this model, there is a common set of parameters which determine the…
Fermion superpartners - neutralinos and charginos in the supersymmetric economical 3-3-1 model are studied. By imposition R parity, their masses and eigenstates are derived. Assuming that Bino-like is dark matter, its mass density is…
Given the conservation of baryon number as well as electron and muon numbers, all present data can be explained without the need of a conserved quantum number for the tau lepton and its neutrino. A supersymmetric extension of the standard…
In this talk we summarize previous work on mass bounds of a light neutralino in the Minimal Supersymmetric Standard Model. We show that without the GUT relation between the gaugino mass parameters M_1 and M_2, the mass of the lightest…
We study the neutralino sector of the left-right supersymmetric model. In addition to the possibilities available in the minimal supersymmetric model, the neutralino states can be superpartners of the U(1)_{B-L} gauge boson, the neutral…
We show that in the Minimal Supersymmetric Standard Model, the mass of the lightest neutralino is experimentally unconstrained if the GUT relation between the gaugino mass parameters M_1 and M_2 is dropped. We discuss what the impact of…
The identity of dark matter is one of the greatest puzzles of our Universe. Its solution may be associated with supersymmetry which is a fundamental space-time symmetry that has not been verified experimentally so far. In many…