56 research outputs found
A general analysis with trilinear and bilinear R-parity violating couplings in the light of recent SNO data
We analyse an extension of the minimal supersymmetric standard model
including the dominant trilinear and bilinear R-parity violating contributions.
We take the trilinear terms from the superpotential and the bilinear terms from
the superpotential as well as the scalar potential. We compute the neutrino
masses induced by those couplings and determine the allowed ranges of the
R-parity violating parameters that are consistent with the latest SNO results,
atmospheric data and the Chooz constraint. We also estimate the effective mass
for neutrinoless double beta decay in such scenarios.Comment: 7 pages, Revtex, 1 PS figur
A Detailed Analysis of One-loop Neutrino Masses from the Generic Supersymmetric Standard Model
In the generic supersymmetric standard model which had no global symmetry
enforced by hand, lepton number violation is a natural consequence.
Supersymmetry, hence, can be considered the source of experimentally demanded
beyond standard model properties for the neutrinos. With an efficient
formulation of the model, we perform a comprehensive detailed analysis of all
one-loop contributions to neutrino masses.Comment: 27 pages Revtex, no figur
Constraints on R-parity violating supersymmetry from leptonic and semileptonic tau, B_d and B_s decays
We put constraints on several products of R-parity violating lambda lambda'
and lambda' lambda' type couplings from leptonic and semileptonic tau, B_d and
B_s decays. Most of them are one to two orders of magnitude better than the
existing bounds, and almost free from theoretical uncertainties. A significant
improvement of these bounds can be made in high luminosity tau-charm or B
factories.Comment: 14 pages, latex. A few references added, two typos corrected. Version
to be published in Physical Review
Focus Point SUSY at the LHC Revisited
The estimation of the backgrounds for gluino signals in focus point
supersymmetry is extended by including the backgrounds from the production of
four third generation quarks in the analysis. We find that these backgrounds
are negligible if one uses the strong selection criteria proposed in the
literature (including this analysis) for heavy gluino searches. Softer
selection criteria often recommended for lighter gluino searches yield
backgrounds which are small but numerically significant. We have also repeated
the more conventional background calculations and compared our results with the
other groups. We find that the size of the total residual background estimated
by different groups using different event generators and hard kinematical cuts
agree approximately. In view of the theoretical uncertainties in the leading
order signal and background cross sections mainly due to the choice of the QCD
scale, the gluino mass reach at the LHC cannot be pinpointed. However,
requiring a signal with tagged b-jets (instead of the standard
choice of ) it is shown that gluino masses close to 2 TeV can be
probed at the LHC for a range of reasonable choices of the QCD scale for an
integrated luminosity of 300 fb.Comment: 17 pages, 4 figures, minor typos correctio
Probing neutrino properties with charged scalar lepton decays
Supersymmetry with bilinear R-parity violation provides a predictive
framework for neutrino masses and mixings in agreement with current neutrino
oscillation data. The model leads to striking signals at future colliders
through the R-parity violating decays of the lightest supersymmetric particle.
Here we study charged scalar lepton decays and demonstrate that if the scalar
tau is the LSP (i) it will decay within the detector, despite the smallness of
the neutrino masses, (ii) the relative ratio of branching ratios Br({tilde
tau}_1 --> e sum nu_i)/ Br({tilde tau}_1 --> mu sum nu_i) is predicted from the
measured solar neutrino angle, and (iii) scalar muon and scalar electron decays
will allow to test the consistency of the model. Thus, bilinear R-parity
breaking SUSY will be testable at future colliders also in the case where the
LSP is not the neutralino.Comment: 24 pages, 8 ps figs Report-no.: IFIC/02-33 and ZU-TH 11/0
Status of a Supersymmetric Flavour Violating Solution to the Solar Neutrino Puzzle with Three Generations
We present a general study of a three neutrino flavour transition model based
on the supersymmetric interactions which violate R-parity. These interactions
induce flavour violating scattering reactions between solar matter and
neutrinos. The model does not contain any vacuum mass or mixing angle for the
first generation neutrino. Instead, the effective mixing in the first
generation is induced via the new interactions. The model provides a natural
interpretation of the atmospheric neutrino anomaly, and is consistent with
reactor experiments. We determine all R-parity violating couplings which can
contribute to the effective neutrino oscillations, and summarize the present
laboratory bounds. Independent of the specific nature of the (supersymmetric)
flavour violating model, the experimental data on the solar neutrino rates and
the recoil electron energy spectrum are inconsistent with the theoretical
predictions. The confidence level of the -analysis ranges between and . The incompatibility, is due to the new SNO
results, and excludes the present model. We conclude that a non-vanishing
vacuum mixing angle for the first generation neutrino is necessary in our
model. We expect this also to apply to the solutions based on other flavour
violating interactions having constraints of the same order of magnitude.Comment: 17 pages, Latex fil
Solar Neutrino Masses and Mixing from Bilinear R-Parity Broken Supersymmetry: Analytical versus Numerical Results
We give an analytical calculation of solar neutrino masses and mixing at
one-loop order within bilinear R-parity breaking supersymmetry, and compare our
results to the exact numerical calculation. Our method is based on a systematic
perturbative expansion of R-parity violating vertices to leading order. We find
in general quite good agreement between approximate and full numerical
calculation, but the approximate expressions are much simpler to implement. Our
formalism works especially well for the case of the large mixing angle MSW
solution (LMA-MSW), now strongly favoured by the recent KamLAND reactor
neutrino data.Comment: 34 pages, 14 ps figs, some clarifying comments adde
Virtual LSPs at e+ e- Colliders
Currently popular search strategies for supersymmetric particles may be
significantly affected due to relatively light sneutrinos which decay
dominantly into invisible channels. In certain cases the second lightest
neutralino may also decay invisibly leading to two extra carriers of missing
energy (in addition to the lightest supersymmetric particle (LSP)) -- the
virtual LSPs (VLSPs). It is shown that if the sneutrino masses happen to be in
the small but experimentally allowed range ~ 45 - 55 GeV, these particles
together with neutralino pairs may contribute significantly to the missing
energy in the process e+ e- ---> \gamma + missing energy at LEP-2 energies as
an enhancement over the Standard Model or the conventional MSSM predictions. It
is further shown that a much larger region of the parameter space can be
scanned at a high luminosity e+ e- collider at 500 GeV like the proposed NLC
machine. Moreover this process can play a complementary role to direct chargino
searches at LEP-2 and NLC which may fail due to a near mass degeneracy of the
chargino and the sneutrino. Formulae for the cross sections taking into account
full mixings of the charginos and the neutralinos are derived. The signal
remains observable even in the context of more restricted models based on N=1
SUGRA with common scalar and gaugino masses. The effect of soft photon
brehmsstrahlung on the signal is also discussed briefly.Comment: 51 pages, LaTeX plus 13 postscript figures included using epsfig in
uuencoded and compressed form, minor comments adde
A multi-targeted approach to suppress tumor-promoting inflammation
Cancers harbor significant genetic heterogeneity and patterns of relapse following many therapies are due to evolved resistance to treatment. While efforts have been made to combine targeted therapies, significant levels of toxicity have stymied efforts to effectively treat cancer with multi-drug combinations using currently approved therapeutics. We discuss the relationship between tumor-promoting inflammation and cancer as part of a larger effort to develop a broad-spectrum therapeutic approach aimed at a wide range of targets to address this heterogeneity. Specifically, macrophage migration inhibitory factor, cyclooxygenase-2, transcription factor nuclear factor-κB, tumor necrosis factor alpha, inducible nitric oxide synthase, protein kinase B, and CXC chemokines are reviewed as important antiinflammatory targets while curcumin, resveratrol, epigallocatechin gallate, genistein, lycopene, and anthocyanins are reviewed as low-cost, low toxicity means by which these targets might all be reached simultaneously. Future translational work will need to assess the resulting synergies of rationally designed antiinflammatory mixtures (employing low-toxicity constituents), and then combine this with similar approaches targeting the most important pathways across the range of cancer hallmark phenotypes
Supersymmetry Breaking and the Supersymmetric Flavour Problem: An Analysis of Decoupling the First Two Generation Scalars
The supersymmetric contributions to the Flavor Changing Neutral Current
processes may be suppressed by decoupling the scalars of the first and second
generations. It is known, however, that the heavy scalars drive the stop mass
squareds negative through the two-loop Renormalization Group evolution. This
tension is studied in detail. Two new items are included in this analysis: the
effect of the top quark Yukawa coupling and the QCD corrections to the
supersymmetric contributions to . Even with Cabibbo-like degeneracy
between the squarks of the first two generations, these squarks must be heavier
than TeV to suppress . This implies, in the case of a
high scale of supersymmetry breaking, that the boundary value of the stop mass
has to be greater than TeV to keep the stop mass squared positive at
the weak scale. Low-energy supersymmetry breaking at a scale that is of the
same order as the mass of the heavy scalars is also considered. In this case
the finite parts of the two-loop diagrams are computed to estimate the
contribution of the heavy scalar masses to the stop mass squared. It is found
that for Cabibbo-like mixing between the squarks, the stop mass at the boundary
needs to be larger than TeV. Thus, for both cases, the large boundary
value of the stop masses leads to an unnatural amount of fine tuning to obtain
the correct mass.Comment: Latex, 40 pages, 14 figures. Replacing an earlier version of the
manuscript. Extra section added discussing limits on from
finetuning, positivity and . Earlier version did not include the
one-loop hypercharge term; this has been corrected, and our conclusions
remain unchange
- …