Search results for "Superpartner"
showing 10 items of 28 documents
B-L-violating masses in softly broken supersymmetry
1997
We prove a general low-energy theorem establishing a generic relation between the neutrino Majorana mass and the superpartner sneutrino B-L-violating "Majorana"-like mass term. The theorem states that, if one of these two quantities is non-zero the other one is also non-zero and, vice versa, if one of them vanishes the other vanishes, too. The theorem is a consequence of the underlying supersymmetry (SUSY) and valid for any realistic gauge model with weak scale softly broken SUSY.
Two-loop gluino contributions to the neutron electric dipole moment in theCP-violating minimal supersymmetric standard model
2005
We analyze two-loop gluino corrections to the neutron electric dipole moment (EDM) in the minimal supersymmetry extension of the standard model (MSSM). The dependence of two-loop corrections on the relevant CP violating phases differs from that of the one-loop contributions, and there is a region in the parameter space where the two-loop contributions are comparable with the one-loop contributions. Our numerical results show that the two-loop corrections can be as large as 30% of the one-loop results.
Phenomenology of supersymmetry with broken R-parity
1985
Abstract In some phenomenological supersymmetric models R -parity (+1 for particles, −1 for sparticles) is spontaneously broken along with tau-lepton number L τ by a vacuum expectation value υ τ of the tau sneutrino ν τ . To avoid excess stellar energy loss through majorons, there should also be explicit L τ violation through right-handed neutrinos. To have a sufficiently light ν τ , either υ τ is very small which is unnatural and boring, and/or the Higgs mixing parameter ϵ is very small. We find that in the limit ϵ → 0: -both the forward-backward asymmetry in e + e − → τ + τ − and the τ lifetime are unchanged, -Z 0 → ggν⊥ decays are possible where ν τ is an extra neutrino, -squarks and glu…
Search for long-lived, heavy particles in final states with a muon and multi-track displaced vertex in proton–proton collisions at s=7 TeV with the A…
2013
Many extensions of the Standard Model posit the existence of heavy particles with long lifetimes. In this Letter, results are presented of a search for events containing one or more such particles, which decay at a significant distance from their production point, using a final state containing charged hadrons and an associated muon. This analysis uses a data sample of proton-proton collisions at root s = 7 TeV corresponding to an integrated luminosity of 4.4 fb(-1) collected in 2011 by the ATLAS detector operating at the Large Hadron Collider. Results are interpreted in the context of R-parity violating supersymmetric scenarios. No events in the signal region are observed and limits are se…
The Minimal Supersymmetric Model without a mu term
2002
We propose a supersymmetric extension of the standard model which is a realistic alternative to the MSSM, and which has several advantages. No ``mu'' supersymmetric Higgs/Higgsino mass parameter is needed for sufficiently heavy charginos. An approximate U(1) R symmetry naturally guarantees that tan beta is large, explaining the top/bottom quark mass hierarchy. This symmetry also suppresses supersymmetric contributions to anomalous magnetic moments, b to s gamma, and proton decay, and these processes place no lower bounds on superpartner masses, even at large tan beta. The soft supersymmetry breaking mass parameters can easily be obtained from either gauge or Planck scale mediation, without …
Flavor physics at large tanβwith a binolike lightest supersymmetric particle
2007
12 pages, 7 figures.-- PACS nrs.: 12.60.Jv; 13.25.Hw; 13.35.-r; 95.35.+d.-- ISI Article Identifier: 000247625300053.-- ArXiv pre-print available at: http://arxiv.org/abs/hep-ph/0703035
Selectron Pair Production in e+e- Colliders and the Supergravity Spectrum
1995
Selectrons may be produced in pairs at LEPII if their mass is less than about 100 GeV. Preferably, they decay into the lightest neutralino plus an electron. In a scenario where selectrons are observed at LEPII, we show that: (i) in a first stage where experimental errors are large, the measurement of the total cross section of selectron pair production, the selectron mass, and the lightest neutralino mass, allow us to validate or rule out the Minimal Supergravity Model in its simplest form, and that (ii) in a second stage where precision measurements are available, the value of $\tan\beta$ can be determined together with the rest of the parameters that specify the Minimal Supergravity Model…
Supersymmetric Unification with Radiative Breaking of R-parity
1996
We show how R-parity can break spontaneously as a result of radiative corrections in unified N=1 supergravity models. We illustrate this with a concrete rank-four unified model, where the spontaneous breaking of R-parity is accompanied by the existence of a physical majoron. We determine the resulting supersymmetric particle mass spectrum and show that R-parity-breaking signals may be detectable at LEP200.
Collider signatures of sneutrino cold dark matter
1999
Decays of sneutrinos are considered in the case that in the presence of lepton-number violation in the sneutrino sector the lighter tau-sneutrino is the Lightest Supersymmetric Particle and the Cold Dark Matter in the Universe. In such circumstances the signals from sparticle decays differ considerably from the ``standard'' case where the lightest neutralino is the Lightest Supersymmetric Particle and it is found that in a wide range of parameters compatible with the sneutrino Cold Dark Matter hypothesis signatures characteristic for such a scenario should be easily observable at for example a Next Linear Collider.
Event rates for CDM detectors from large-scale shell-model calculations
2006
Abstract We investigate the scattering of the CDM candidate LSP (Lightest Supersymmetric Particle) off nuclei. We have computed the associated event rates and annual modulation signals for the 23 Na, 71 Ga, 73 Ge and 127 I CDM detectors by using the nuclear shell model in realistic model spaces and exploiting microscopic effective two-body interactions. Large-scale computations had to be performed in order to achieve convergence of the results. We have tabulated the associated nuclear-structure coefficients for several LSP masses enabling easy interpolation of our results for any other mass. The relevance of the spin-dependent and coherent channels for the event rates is discussed, from bot…