Using Tau Polarization to Discriminate between SUSY Models and Determine SUSY Parameters at ILC

In many SUSY models the first SUSY signal in the proposed International Linear Collider is expected to come from the pair production of $\tilde\tau_1$, followed by its decay into $\tau$+LSP. We study a simple and robust method of measuring the polarization of this $\tau$ in its 1-prong hadronic decay channel,and show how it can be used to discriminate between SUSY models and to determine SUSY parameters.Comment: 9 pages, 5 figures, minor corrections; version published in Phys. Lett.

Updated Reach of the CERN LHC and Constraints from Relic Density, b->s gamma and a(mu) in the mSUGRA Model

{We present an updated assessment of the reach of the CERN LHC pp collider for supersymmetric matter in the context of the minimal supergravity (mSUGRA) model. In addition to previously examined channels, we also include signals with an isolated photon or with a leptonically decaying Z boson. For an integrated luminosity of 100 fb^{-1}, values of m_{1/2}\sim 1400 GeV can be probed for small m_0, corresponding to a gluino mass of m_{\tg}\sim 3 TeV. For large m_0, in the hyperbolic branch/focus point region, m_{1/2}\sim 700 GeV can be probed, corresponding to m_{\tg}\sim 1800 GeV. We also map out parameter space regions preferred by the measured values of the dark matter relic density, the b\to s\gamma decay rate, and the muon anomalous magnetic moment a_\mu, and discuss how SUSY might reveal itself in these regions. We find the CERN LHC can probe the entire stau co-annihilation region and also most of the heavy Higgs annihilation funnel allowed by WMAP data, except for some range of large m_0 and m_{1/2} if \tan\beta \agt 50.Comment: 22 page latex file including 10 EPS figures; bug fix in relic density code modifies figures in co-annihilation regio

Physics Prospects at the Hadron Colliders

I start with a brief introduction to the elementary particles and their interactions, Higgs mechanism and supersymmetry. The major physics objectives of the Tevatron and LHC colliders are identified. The status and prospects of the top quark, charged Higgs boson and superparticle searches are discussed in detail, while those of the neutral Higgs boson(s) are covered in a parallel talk by R.J.N. Phillips at this workshop.Comment: 16 pages Latex + 15 figures (available on request

Single gluino production in the R-parity lepton number violating MSSM at the LHC

We examine the $R_{p}$-violating signal of single gluino production associated with a charged lepton or neutrino at the large hadron collider (LHC), in the model of R-parity relaxed supersymmetric model. If the parameters in the ${\rlap/R}_p$ supersymmetric interactions are not too small, and the mass of gluino is considered in the range from several GeV (as the Lightest Supersymmetric Particle) to 800 GeV, the cross section of the single gluino production via Drell-Yan processes can be in the order of $10^2 \sim 10^3$ femto barn, and that via gluon fusion in the order of $10^{-1} \sim 10^3$ femto barn. If the gluino decay can be well detected in the CERN LHC, this process provides a prospective way to probe supersymmetry and $R_p$ violation.Comment: LaTex, 22 pages, 5 EPS file

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

Probing mSUGRA via the Extreme Universe Space Observatory

An analysis is carried out within mSUGRA of the estimated number of events originating from upward moving ultra-high energy neutralinos that could be detected by the Extreme Universe Space Observatory (EUSO). The analysis exploits a recently proposed technique that differentiates ultra-high energy neutralinos from ultra-high energy neutrinos using their different absorption lengths in the Earth's crust. It is shown that for a significant part of the parameter space, where the neutralino is mostly a Bino and with squark mass $\sim 1$ TeV, EUSO could see ultra-high energy neutralino events with essentially no background. In the energy range 10^9 GeV < E < 10^11 GeV, the unprecedented aperture of EUSO makes the telescope sensitive to neutralino fluxes as low as 1.1 \times 10^{-6} (E/GeV)^{-1.3} GeV^{-1} cm^{-2} yr^{-1} sr^{-1}, at the 95% CL. Such a hard spectrum is characteristic of supermassive particles' $N$-body hadronic decay. The case in which the flux of ultra-high energy neutralinos is produced via decay of metastable heavy particles with uniform distribution throughout the universe is analyzed in detail. The normalization of the ratio of the relics' density to their lifetime has been fixed so that the baryon flux produced in the supermassive particle decays contributes to about 1/3 of the events reported by the AGASA Collaboration below 10^{11} GeV, and hence the associated GeV gamma-ray flux is in complete agreement with EGRET data. For this particular case, EUSO will collect between 4 and 5 neutralino events (with 0.3 of background) in ~ 3 yr of running. NASA's planned mission, the Orbiting Wide-angle Light-collectors (OWL), is also briefly discussed in this context.Comment: Some discussion added, final version to be published in Physical Review

The MSSM invisible Higgs in the light of dark matter and g-2

Giving up the assumption of the gaugino mass unification at the GUT scale, the latest LEP and Tevatron data still allow the lightest supersymmetric Higgs to have a large branching fraction into invisible neutralinos. Such a Higgs may be difficult to discover at the LHC and is practically unreachable at the Tevatron. We argue that, for some of these models to be compatible with the relic density, light sleptons with masses not far above the current limits are needed. There are however models that allow for larger sleptons masses without being in conflict with the relic density constraint. This is possible because these neutralinos can annihilate efficiently through a Z-pole. We also find that many of these models can nicely account, at the 2\sigma level, for the discrepancy in the latest g-2 measurement. However, requiring consistency with the g-2 at the 1\sigma level, excludes models that lead to the largest Higgs branching fraction into LSP's. In all cases one expects that even though the Higgs might escape detection, one would have a rich SUSY phenomenology even at the Tevatron, through the production of charginos and neutralinos.Comment: 16 pages and 5 figures. New references added, text and figures unchange

Acceptance of candidate baits by domestic dogs for delivery of oral rabies vaccines

Protocols for evaluating oral rabies vaccine baits for domestic dogs were field tested in central Mexico, after which dog-food manufacturers and suppliers to the pet-food industry were advised as to potential ingredients for use in prototype dog baits. Bait-preference trials in which confined dogs were used were then undertaken, followed by field tests of free-ranging farmer-owned dogs in three towns in the Nile River Delta region of Egypt. Both confined and free-ranging dogs showed strong preferences for certain baits or bait coatings (poultry, beef tallow, cheese, egg and a proprietary product). Fish-meal polymer baits, widely used for wildlife species, were less preferred. In Egypt, a commercial dog-food-meal bait coated with beef tallow and dry cheese was consumed at a rate approaching that of a chicken-head bait. The percentage baits that were actually eaten after they had been offered to dogs, ranged from 71-96% for household dogs tested in Mexico, 65-91% for confined dogs (beagles and mixed breeds) tested in the United States, and 32-88% for farmer-owned dogs tested in Egypt.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat X Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Implications of the HERA Events for the R-Parity Breaking SUSY Signals at Tevatron

The favoured R-parity violating SUSY scenarios for the anomalous HERA events correspond to top and charm squark production via the $\lambda'_{131}$ and $\lambda'_{121}$ couplings. In both cases the corresponding electronic branching fractions of the squarks are expected to be $\ll 1$. Consequently the canonical leptoquark signature is incapable of probing these scenarios at the Tevatron collider over most of the MSSM parameter space. We suggest alternative signatures for probing them at Tevatron, which seem to be viable over the entire range of MSSM parameters.Comment: 20 pages Latex file with 4 ps files containing 4 figure