1,620 research outputs found
Invisible Decays of the Supersymmetric Higgs and Dark Matter
We discuss effects of the light sparticles on decays of the lightest Higgs in
a supersymmetric model with nonuniversal gaugino masses at the high scale,
focusing on the `invisible' decays into neutralinos. These can impact
significanlty the discovery possibilities of the lightest Higgs at the LHC. We
show that due to these decays, there exist regions of the space where
the B.R. becomes dangerously low even after imposing
the LEP constraints on the sparticle masses, implying a possible preclusion of
its discovery in the channel. We find that there exist regions
in the parameter space with acceptable relic density and where the ratio falls
below 0.6, implying loss of signal in the channel. These
regions correspond to masses which should be
accessible already at the Tevatron. Further we find that considerations of
relic density put lower limit on the U(1) gaugino mass parameter
independently of and .Comment: 17 pages, 11 figures, Talk presented at Appi2002, Accelerator and
Particle Physics Institute, Appi, Iwate, Japan, February 13--16 200
{\Large{\bf Higgs or Neutral Vector Boson Production with a Pair in {\LARGE } Collisions}}
Exploiting the fact that pair production in high-energy
collisions is very large, we use this process to trigger Higgs, or photon
radiation. We find that there are sizeable rising cross-sections for triple
bosons production. At energies about the new mechanism for Higgs
production becomes very competitive with the dominant Higgs production
processes in and reactions. The effect of different
polarized photon spectra obtained through back-scattered laser light on the
electron beam of a linear collider is investigated . We give a special
attention to the search of the intermediate mass Higgs in production and
discuss how to effectively suppress the backgrounds.Comment: ENSLAPP-A-430/93, 14 pages, plus 6 figures available through mail or
fax upon reques
Uncertainties in the Prediction of the Relic Density of Supersymmetric Dark Matter
We investigate how well the relic density of dark matter can be predicted in
mSUGRA. We determine the parameters to which the relic density is most
sensitive and quantify the collider accuracy needed to match the accuracy of
WMAP and PLANCK.Comment: 4 pages, 1 figure, presented at LCWS, Paris, April 200
Extracting constraints from direct detection searches of supersymmetric dark matter in the light of null results from the LHC in the squark sector
The comparison of the results of direct detection of Dark Matter, obtained
with various target nuclei, requires model-dependent, or even arbitrary,
assumptions. Indeed, to draw conclusions either the spin-dependent (SD) or the
spin-independent (SI) interaction has to be neglected. In the light of the null
results from supersymmetry searches at the LHC, the squark sector is pushed to
high masses. We show that for a squark sector at the TeV scale, the framework
used to extract contraints from direct detection searches can be redefined as
the number of free parameters is reduced. Moreover, the correlation observed
between SI and SD proton cross sections constitutes a key issue for the
development of the next generation of Dark Matter detectors.Comment: Figure 3 has been updated. Conclusions unchange
Electroweak corrections to Higgs production through ZZ fusion at the linear collider
We present the full order alpha electroweak radiative corrections to e+e- ->
e+e-H. The computation is performed with the help of GRACE-loop. The extraction
of the full QED corrections is performed, these are quite large at threshold.
The genuine weak corrections, for the linear collider energies, when expressed
in the G_mu scheme are of order -2 to -4 for Higgs masses preferred by the
latest precision data. We also extract the m_t^2 type corrections and make a
comparison with the weak corrections for the process e+e- ->nu nu H.Comment: 16 pages and 6 figure
SUSY Higgs at the LHC: large stop mixing effects and associated production
We revisit the effect of the large stop mixing on the decay and production of the lightest SUSY Higgs at the LHC. We stress that whenever the inclusive 2-photon signature is substantially reduced, associated production, and , with the subsequent decay of the Higgs into photons is enhanced and becomes an even more important discovery channel. We also point out that these reductions in the inclusive channel do not occur for the smallest Higgs mass where the significance is known to be lowest. We show that in such scenarios the Higgs can be produced in the decay of the heaviest stop. For not too heavy masses of the pseudo-scalar Higgs where the inclusive channel is even further reduced, we show that large stop mixing also allows the production of the pseudo-scalar Higgs through stop decays. These large mixing scenarios therefore offer much better prospects than previously thought. As a by-product we have recalculated stop1-stop1-h production at the LHC and give a first evaluation of stop1-stop1-Z
Semi-leptonic four-fermion final states in polarised \gamma\gamma reactions: Exact results vs an improved narrow width approximation
We calculate the process with the full set of Feynman diagrams. We consider different
implementations of the width and different combinations of the photon
polarisations. The results of an improved narrow width approximation based on
with full spin-correlations that takes into
account different angular cuts as well as cuts on the invariant masses are
compared to those of the complete calculation.Comment: paper in LATEX, 19 pages, 3 figures. Complete psfile available via
anonymous ftp at ftp://lapphp0.in2p3.fr/pub/preprints-theorie/enslapp635.uu
or at http://lapphp0.in2p3.fr/preplapp/psth/enslapp635.ps.g
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