5,712 research outputs found
Supersymmetric lepton flavour violation in a linear collider: the role of charginos
The occurrence of a significant amount of supersymmetric lepton flavour
violation at laboratory energies, through
mixing, has become a realistic possibility in the wake of the super-Kamiokande
atmospheric neutrino result. This effect can be observed in an e+e- linear
collider with the distinct final state tau+mu+ jets+E_T. We show that the pair
production of charginos can make an important contribution to this process and
has to be taken into account in addition to that of sneutrinos or charged
sleptons. Some case studies are presented with CM energies of 500 and 800 GeV
and integrated luminosities of 50, 500 and 1000 fb-1.Comment: 15 pages, latex, including 2 figure
The interplay between the charged Higgs and squark-gluino events at the LHC
In some extensions of the standard model with extended Higgs sectors, events
from new particle production may pass the selection criteria for Higgs search
in different channels at the LHC - 14 TeV and mimic Higgs signals. This
intriguing possibility is illustrated by PYTHIA based simulations using several
representative points in the parameter space of the minimal supersymmetric
standard model (MSSM) including a point in the minimal supergravity model
consistent with the Dark matter (DM) relic density data. Our simulations
explore the interplay between the charged Higgs signal and typical
squark-gluino events. We argue that the standard selections like the one based
on the polarization properties of the 's from charged Higgs decay, though
adequate for handling the SM background, may not be very efficient in the
presence of SUSY backgrounds. We then propose an alternative search strategy
based on pure kinematics which sufficiently controls both the SM and the MSSM
backgrounds. For charged Higgs masses () in the deep decoupling regime
(600 GeV \lsim m_{H^{\pm}} \lsim 800 GeV) this method works well and extends
the LHC reach close to 800 GeV for an integrated luminosity of 30
with or without the SUSY background. For a lighter charged Higgs a judicious
combination of the old selections and some of the cuts proposed by us may
disentangle the Higgs signal from the squark-gluino backgrounds quite
effectively
Chargino Pair Production at Colliders with Polarized Beams
The chargino system can be reconstructed completely
in collisions. By measuring the total cross sections and the
asymmetries with polarized beams in , the chargino masses and the gaugino-higgsino mixing angles of these
states can be determined very accurately. If only the lightest charginos
are kinematically accessible, transverse beam polarization
is needed to determine the mixing angles unambiguously. From these observables
the fundamental SUSY parameters can be derived: the SU(2) gaugino mass ,
the modulus and the cosine of the CP-violating phase of the higgsino mass
parameter , and , the ratio of the vacuum expectation
values of the two neutral Higgs doublet fields. [The remaining two-fold
ambiguity of the phase can be resolved by measuring the normal polarization of
the charginos.]Comment: 19 pages including 4 figure
CP Phases in Supersymmetric Tri-lepton Signals at the Tevatron
We have analyzed the supersymmetric tri-lepton signals for sparticle searches
at the Tevatron in the minimal supersymmetric standard model with general CP
phases without generational mixing. The CP phases may affect very strongly the
chargino and neutralino mass spectrums and
as well as and . Even under the stringent
constraints from the electron electric dipole moment the CP phases can lead to
a minimum of the tri-lepton event rate for their non-trivial values.Comment: 10 pages, 3 eps figures, largely revised by including the electron
EDM constraint
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
Using Tau Polarization for Charged Higgs Boson and SUSY Searches at LHC
The polarization can be easily measured at LHC in the 1-prong hadronic
decay channel by measuring what fraction of the -jet momentum is
carried by the charged track. A simple cut requiring this fraction to be >0.8
retains most of the polarization of +1 -jet signal while
suppressing the polarization of -1 -jet background and practically
eliminating the fake background. This can be utilized to extract the
charged Higgs signal. It can be also utilized to extract the SUSY signal in the
stau NLSP region, and in particular the stau co-annihilaton region.Comment: 8 pages, 9 figures; Fig.8 and Fig.9 are replaced, published in
"Physics at the Large Hadron Collider", A Platinum Jubilee Special Issue of
the Indian National Science Academy, Springer (2009) p 20
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