2,255 research outputs found

### Limits on SUSY particle Spectra from Proton Stability and Dark Matter Constraints

It is shown that the combined constraints on the amount of cold dark matter
and of proton stability produce a stringent upper limit on the gluino mass
$m_{\tilde g}$ (and hence on the lightest neutralino mass $m_{\chi_1^0}\simeq
m_{\tilde g}/7$) for a large class of gravity mediated supergravity unified
models. One finds that for the minimal SU(5) model current data (Kamiokande)
restricts $m_{\tilde g}\leq 400$ GeV for a scalar soft breaking mass $m_0\leq
1$ TeV. Expected future data from Super Kamionkande and ICARUS will be
sensitive to the entire range of gluino mass for $m_0\leq 1$ TeV, and be able
to exclude the region $m_{\tilde g}\geq 500$ GeV for $m_0\leq 5$ TeV. Effects
of quark mass textures are studied and one finds that the bound $m_{\tilde
g}\leq 500$ GeV holds when the experimental proton lifetime for the $p\to \bar
\nu K^+$ mode becomes $\geq 5\times 10^{32}$ yr.Implications of these results
for a test of these models at the Tevatron and at the LHC are discussed. The
effects of non-universal soft breaking in the Higgs and the third generation
squark sectors are also examined, and it is found that the proton lifetime is
sensitive to these non-universal effects. The current data already eliminates
some regions of non-universalities. The constraints of proton stability on the
direct detection of dark matter are seen to reduce the maximum event rates by
as much as a factor of $10^3$.Comment: 13 pages including 5 figure

### Neutralino Proton Cross Sections In Supergravity Models

The neutralino-proton cross section is examined for supergravity models with
R-parity invariance with universal and non-universal soft breaking. The region
of parameter space that dark matter detectors are currently (or will be
shortly) sensitive i.e. $(0.1-10)\times 10^{-6}$ pb, is examined. For universal
soft breaking (mSUGRA), detectors with sensitivity
$\sigma_{\tilde{\chi}_{1}^{0}-p} \geq 1 \times 10^{-6}$ pb will be able to
sample parts of the parameter space for $\tan \beta \stackrel{>}{\sim} 25$.
Current relic density bounds restrict $m_{\tilde{\chi}_{1}^{0}} \leq 120$ GeV
for the maximum cross sections, which is below where astronomical uncertainties
about the Milky Way are relevant. Nonuniversal soft breaking models can allow
much larger cross sections and can sample the parameter space for $\tan \beta
\stackrel{>}{\sim} 4$. In such models, $m_0$ can be quite large reducing the
tension between proton decay bounds and dark matter analysis. We note the
existance of two new domains where coannihilation effects can enter, i.e. for
mSUGRA at large $\tan \beta$, and for nonuniversal models with small $\tan
\beta$.Comment: 22 pages, latex, 18 figure

### Dark Matter in SUSY Models

Direct detection experiments for neutralino dark matter in the Milky Way are
examined within the framework of SUGRA models with R-parity invariance and
grand unification at the GUT scale, M_G. Models of this type apply to a large
number of phenomena, and all existing bounds on the SUSY parameter space due to
current experimental constraints are included. For models with universal soft
breaking at M_G (mSUGRA), the Higgs mass and b\to s\gamma constraints imply
that the gaugino mass, m_{1/2}, obeys m_{1/2} >(300-400)GeV putting most of the
parameter space in the co-annihilation domain where there is a relatively
narrow band in the m_0 - m_{1/2} plane. For $\mu > 0$ we find that the
neutralino -proton cross section >~ 10^{-10} pb for m_{1/2} < 1 TeV, making
almost all of this parameter space accessible to future planned detectors. For
\mu < 0, however, there will be large regions of parameter space with cross
sections < 10^{-12} pb, and hence unaccessible experimentally. If, however, the
muon magnetic moment anomaly is confirmed, then \mu >0 and m_{1/2}<~ 800 GeV.
Models with non-universal soft breaking in the third generation and Higgs
sector can allow for new effects arising from additional early universe
annihilation through the Z-channel pole. Here cross sections that will be
accessible in the near future to the next generation of detectors can arise,
and can even rise to the large values implied by the DAMA data. Thus dark
matter detectors have the possibility of studying the the post-GUT physics that
control the patterns of soft breaking.Comment: 13 pages, latex, 10 figures, invited talk at NANP-01, Dubna, Russia,
June 19--23, 200

### Gravitational Forces on the Branes

We examine the gravitational forces in a brane-world scenario felt by point
particles on two 3-branes bounding a 5-dimensional AdS space with $S^{1}/Z_2$
symmetry. The particles are treated as perturbations on the vacuum metric and
coordinate conditions are chosen so that no brane bending effects occur. We
make an ADM type decomposition of the metric tensor and solve Einstein's
equations to linear order in the static limit. While no stabilization mechanism
is assumed, all the 5D Einstein equations are solved and are seen to have a
consistent solution. We find that Newton's law is reproduced on the Planck
brane at the origin while particles on the TeV brane a distance $y_2$ from the
origin experience an attractive force that has a growing exponential dependence
on the brane position.Comment: Based on a talk given at PASCOS 2004/Pran Nath Fes

### Developments in Supergravity Unified Models

A review is given of developments in supergravity unified models proposed in
1982 and their implications for current and future experiment are discussed.Comment: 24 pages, 1 figure. To appear in "Perspectives on Supersymmetry II"",
edited by Gordon Kan

### Supergravity Unified Models

The development of supergravity unified models and their implications for
current and future experiments are discussed.Comment: Latex, 21 pages, to appear in book "Perspectives on Supergravity",
World Scientific, Editor G. Kane; reference numbers and minor typos correcte

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