393 research outputs found
Decaying neutralino dark matter in anomalous models
In supersymmetric models extended with an anomalous different
R-parity violating couplings can yield an unstable neutralino. We show that in
this context astrophysical and cosmological constraints on neutralino decaying
dark matter forbid bilinear R-parity breaking neutralino decays and lead to a
class of purely trilinear R-parity violating scenarios in which the neutralino
is stable on cosmological scales. We have found that among the resulting models
some of them become suitable to explain the observed anomalies in cosmic-ray
electron/positron fluxes.Comment: 19 pages, 3 figures. References added, typos corrected, accepted
version in Phys Rev
Bounds on Broken R-Parity from Leptonic Meson Decays
Investigating leptonic decays of pi^-, K^-, B^-, pi^0, K_L^0, B_s^0 we
present new bounds on some products of two R-parity violating coupling
constants. For mesons of a similar structure but so far poor experimental data
we give the corresponding formulae, to be used in the future.Comment: Latex, 15 pages, 1 figure; final version which appeared in Phys.Rev.
Minimal supersymmetric standard model with gauge mediated supersymmetry breaking and neutrinoless double beta decay
The Minimal Supersymmetric Standard Model with gauge mediated supersymmetry
breaking and trilinear R-parity violation is applied to the description of
neutrinoless double beta decay. A detailed study of limits on the parameter
space coming from the B to (X,gamma) processes by using the recent CLEO results
is performed. The importance of two-nucleon and pion-exchange realizations of
neutrinoless double beta decay together with gluino and neutralino
contributions to this process are addressed. We have deduced new limits on the
trilinear R-parity breaking parameter lambda_{111}' from the non-observability
of 0 nu beta beta in several medium and heavy open-shell nuclei for different
gauge mediated breaking scenarios. In general, they are stronger than those
known from other analyses. Also some studies with respect to the future
neutrinoless double beta decay projects are presented.Comment: 10 pages, 7 figure
Neutrino masses in with adjoint flavons
We present a supersymmetric model for neutrino masses
and mixings that implements the seesaw mechanism by means of the heavy SU(2)
singlets and triplets states contained in three adjoints of SU(5). We discuss
how Abelian symmetries can naturally yield non-hierarchical light
neutrinos even when the heavy states are strongly hierarchical, and how it can
also ensure that --parity arises as an exact accidental symmetry. By
assigning two flavons that break to the adjoint representation of
SU(5) and assuming universality for all the fundamental couplings, the
coefficients of the effective Yukawa and Majorana mass operators become
calculable in terms of group theoretical quantities. There is a single free
parameter in the model, however, at leading order the structure of the light
neutrinos mass matrix is determined in a parameter independent way.Comment: 16 pages, 9 figures. Included contributions to neutrino masses from
the triplet states contained in the three adjoints of SU(5
Like Sign Dilepton Signature for R-Parity Violating SUSY Search at the Tevatron Collider
The like sign dileptons provide the most promising signature for
superparticle search in a large category of -parity violating SUSY models.
We estimate the like sign dilepton signals at the Tevatron collider, predicted
by these models, over a wide region of the MSSM parameter space. One expects an
unambiguous signal upto a gluino mass of GeV ( GeV) with
the present (proposed) accumulated luminosity of .Comment: 12 page LaTeX file; 5 figures available upon request from the autho
CP asymmetries in the supersymmetric trilepton signal at the LHC
In the CP-violating Minimal Supersymmetric Standard Model, we study the
production of a neutralino-chargino pair at the LHC. For their decays into
three leptons, we analyze CP asymmetries which are sensitive to the CP phases
of the neutralino and chargino sector. We present analytical formulas for the
entire production and decay process, and identify the CP-violating
contributions in the spin correlation terms. This allows us to define the
optimal CP asymmetries. We present a detailed numerical analysis of the cross
sections, branching ratios, and the CP observables. For light neutralinos,
charginos, and squarks, the asymmetries can reach several 10%. We estimate the
discovery potential for the LHC to observe CP violation in the trilepton
channel.Comment: 39 pages, 8 figures, version to appear in EPJC, discussion(s) added,
typo in (D.79), (D.118) corrected, new Fig. 7; The European Physical Journal
C, Volume 72, Issue 3, 201
Like Sign Dilepton Signature for Gluino Production at LHC with or without R Conservation
The isolated like sign dilepton signature for gluino production is
investigated at the LHC energy for the conserving as well as the and
violating SUSY models over a wide range of the parameter space. One gets
viable signals for gluino masses of 300 and 600 GeV for both conserving and
violating models, while it is less promising for the violating case.
For a 1000 GeV gluino, the violating signal should still be viable; but the
conserving signal becomes too small at least for the low luminosity option
of LHC.Comment: (e-mail: [email protected]) Latex: No. of pages 21, no. of figures
6 - available on reques
Impact of R-Parity Violation on Supersymmetry Searches at the Tevatron
We evaluate cross sections for \eslt, 1 and various dilepton and
multilepton event topologies that result from the simultaneous production of
all sparticles at the Tevatron collider, both within the minimal model
framework as well as in two different -parity violating scenarios. Our
analysis assumes that these -violating couplings are small, and that their
sole effect is to cause the lightest supersymmetric particle to decay inside
the detector. We reassess future strategies for sparticle searches at the
Tevatron, and quantify by how much the various signals for supersymmetry could
differ from their minimal model expectations, if -parity is not conserved
due to either baryon number or lepton number violating operators. We also
evaluate the Tevatron reach in for the various models, and find that
rate-limited multilepton signals ultimately provide the largest reach for both
-parity conserving and -parity violating cases.Comment: preprint nos. FSU-HEP-941001, UR-1387, ER-40685-836 and
UH-511-807-94, 13 pages (REVTEX) plus 3 uuencoded figures attache
A remark on sphaleron erasure of baryon asymmetry
We complete an existing result for how the baryon asymmetry left over after a
period of full thermal equilibrium depends on different lepton asymmetries.Comment: 5 pages; small clarifications and a reference added; to appear in PR
The Supersymmetric Standard Models with Decay and Stable Dark Matters
We propose two supersymmetric Standard Models (SMs) with decaying and stable
dark matter (DM) particles. To explain the SM fermion masses and mixings and
have a heavy decay DM particle S, we consider the Froggatt-Nielsen mechanism by
introducing an anomalous U(1)_X gauge symmetry. Around the string scale, the
U(1)_X gauge symmetry is broken down to a Z_2 symmetry under which S is odd
while all the SM particles are even. S obtains a vacuum expectation value
around the TeV scale, and then it can three-body decay dominantly to the
second/third family of the SM leptons in Model I and to the first family of the
SM leptons in Model II. Choosing a benchmark point in the constrained minimal
supersymmetric SM with exact R parity, we show that the lightest neutralino DM
is consistent with the CDMS II experiment. Considering S three-body decay and
choosing suitable parameters, we show that the PAMELA and Fermi-LAT experiments
and the PAMELA and ATIC experiments can be explained in Model I and Model II,
respectively.Comment: RevTex4, 26 pages, 6 figures, references added, version to appear in
EPJ
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