Shadows of the Planck Scale: The Changing Face of Compactification Geometry

By studying the effects of the shape moduli associated with toroidal compactifications, we demonstrate that Planck-sized extra dimensions can cast significant ``shadows'' over low-energy physics. These shadows can greatly distort our perceptions of the compactification geometry associated with large extra dimensions, and place a fundamental limit on our ability to probe the geometry of compactification simply by measuring Kaluza-Klein states. We also discuss the interpretation of compactification radii and hierarchies in the context of geometries with non-trivial shape moduli. One of the main results of this paper is that compactification geometry is effectively renormalized as a function of energy scale, with ``renormalization group equations'' describing the ``flow'' of geometric parameters such as compactification radii and shape angles as functions of energy.Comment: 7 pages, LaTeX, 2 figure

An Updated Description of Heavy-Hadron Interactions in Geant-4

Exotic stable massive particles (SMP) are proposed in a number of scenarios of physics beyond the Standard Model. It is important that LHC experiments are able both to detect and extract the quantum numbers of any SMP with masses around the TeV scale. To do this, an understanding of the interactions of SMPs in matter is required. In this paper a Regge-based model of R-hadron scattering is extended and implemented in Geant-4. In addition, the implications of $R$-hadron scattering for collider searches are discussed

A solution to the mu problem in the presence of a heavy gluino LSP

In this paper we present a solution to the $\mu$ problem in an SO(10) supersymmetric grand unified model with gauge mediated and D-term supersymmetry breaking. A Peccei-Quinn symmetry is broken at the messenger scale $M\sim 10^{12}$ GeV and enables the generation of the $\mu$ term. The boundary conditions defined at $M$ lead to a phenomenologically acceptable version of the minimal supersymmetric standard model with novel particle phenomenology. Either the gluino or the gravitino is the lightest supersymmetric particle (LSP). If the gravitino is the LSP, then the gluino is the next-to-LSP (NLSP) with a lifetime on the order of one month or longer. In either case this heavy gluino, with mass in the range 25 - 35 GeV, can be treated as a stable particle with respect to experiments at high energy accelerators. Given the extensive phenomenological constraints we show that the model can only survive in a narrow region of parameter space resulting in a light neutral Higgs with mass $\sim 86 - 91$ GeV and $\tan\beta \sim 9 - 14$. In addition the lightest stop and neutralino have mass $\sim 100 - 122$ GeV and $\sim 50 - 72$ GeV, respectively. Thus the model will soon be tested. Finally, the invisible axion resulting from PQ symmetry breaking is a cold dark matter candidate.Comment: 30 pages, 9 figure

Interactions of Heavy Hadrons using Regge Phenomenology and the Quark Gluon String Model

The search for stable heavy exotic hadrons is a promising way to observe new physics processes at collider experiments. The discovery potential for such particles can be enhanced or suppressed by their interactions with detector material. This paper describes a model for the interactions in matter of stable hadrons containing an exotic quark of charges $\pm {1/3}e$ or $\pm {2/3}e$ using Regge phenomenology and the Quark Gluon String Model. The influence of such interactions on searches at the LHC is also discussed

On the support of general local cohomology modules and filter regular sequences

Let R be a commutative Noetherian ring with non-zero identity and a an ideal of R. In the present paper, we examine the question whether the support of Hn a (N;M) must be closed in Zariski topology, where Hn a (N;M) is the nth general local cohomology module of nitely generated R-modules M and N with respect to the ideal a

SUSY GUTs under Siege : Proton Decay

SO(10) supersymmetric grand unified theories [SUSY GUTs] provide a beautiful framework for physics beyond the standard model. Experimental measurements of the three gauge couplings are consistent with unification at a scale $M_G \sim 3 \times 10^{16}$ GeV. In addition predictive models for fermion masses and mixing angles have been found which fit the low energy data, including the recent data for neutrino oscillations. SO(10) boundary conditions can be tested via the spectrum of superparticles. The simplest models also predict neutron and proton decay rates. In this paper we discuss nucleon decay rates and obtain reasonable upper bounds. A clear picture of the allowed SUSY spectra as constrained by nucleon decay is presented.Comment: 13 page

An analysis of a Heavy Gluino LSP at CDF : The Heavy Gluino Window

In this paper we consider a heavy gluino to be the lightest supersymmetric particle [LSP]. We investigate the limits on the mass of a heavy gluino LSP, using the searches for excess events in the jets plus missing momentum channel in Run I. The neutral and charged R-hadrons, containing a heavy gluino LSP, have distinct signatures at the Fermilab Tevatron. The range of excluded gluino masses depends on whether the R-hadron is charged or neutral and the amount of energy deposited in the hadronic calorimeter. The latter depends on the energy loss per collision in the calorimeter and the number of collisions; where both quantities require a model for R-hadron- Nucleon scattering. We show how the excluded range of gluino mass depends on these parameters. We find that gluinos with mass in the range between $\sim 35$ GeV and $\sim 115$ GeV are excluded by CDF Run I data. Combined with previous results of Baer et al., which use LEP data to exclude the range 3 - 22$\sim$25 GeV, our result demonstrates that an allowed window for a heavy gluino with mass between 25 and 35 GeV is quite robust. Finally we discuss the relevant differences of our analysis of Tevatron data to that of Baer et al.Comment: 36 pages, 11 figures, added an acknowledgemen

Top-squark searches at the Tevatron in models of low-energy supersymmetry breaking

We study the production and decays of top squarks (stops) at the Tevatron collider in models of low-energy supersymmetry breaking. We consider the case where the lightest Standard Model (SM) superpartner is a light neutralino that predominantly decays into a photon and a light gravitino. Considering the lighter stop to be the next-to-lightest Standard Model superpartner, we analyze stop signatures associated with jets, photons and missing energy, which lead to signals naturally larger than the associated SM backgrounds. We consider both 2-body and 3-body decays of the top squarks and show that the reach of the Tevatron can be significantly larger than that expected within either the standard supergravity models or models of low-energy supersymmetry breaking in which the stop is the lightest SM superpartner. For a modest projection of the final Tevatron luminosity, L = 4 fb-1, stop masses of order 300 GeV are accessible at the Tevatron collider in both 2-body and 3-body decay modes. We also consider the production and decay of ten degenerate squarks that are the supersymmetric partners of the five light quarks. In this case we find that common squark masses up to 360 GeV are easily accessible at the Tevatron collider, and that the reach increases further if the gluino is light.Comment: 32 pages, 9 figures; references adde

Yukawa Deflected Gauge Mediation

We consider models which are natural extensions of those where supersymmetry is broken at low energy scales and transmitted to visible matter by gauge interactions. We investigate the situation where the quark and lepton superfields of the MSSM are localized to a brane in a higher dimensional space while the messenger fields and the sector which breaks supersymmetry dynamically are localized to another brane in the same space. The MSSM gauge and Higgs fields are assumed to propagate in the bulk. If some of the messenger fields and the Higgs fields have the same quantum numbers, this allows the possibility of mixing between these fields so that the physical Higgs and messenger fields are admixtures of the brane and bulk fields. This manifests itself in direct couplings of the quark and lepton fields to the physical messengers that are proportional to the MSSM Yukawa couplings and hence preserve the flavor structure of the CKM matrix. The result is new contributions to the soft supersymmetry breaking parameters that are related to the Yukawa couplings and which therefore naturally satisfy the constraints from FCNC's. For messenger scales greater then 1000 TeV these new contributions are parametrically of the same order of magnitude as gauge mediation. This scenario naturally avoids the cosmological problems associated with stable messengers and admits a simple and natural solution to the $\mu$ problem based on the NMSSM.Comment: 19 pages, expressions for down-type Higgs trilinear terms corrected, conclusions unchange

Where the Sidewalk Ends: Jets and Missing Energy Search Strategies for the 7 TeV LHC

This work explores the potential reach of the 7 TeV LHC to new colored states in the context of simplified models and addresses the issue of which search regions are necessary to cover an extensive set of event topologies and kinematic regimes. This article demonstrates that if searches are designed to focus on specific regions of phase space, then new physics may be missed if it lies in unexpected corners. Simple multiregion search strategies can be designed to cover all of kinematic possibilities. A set of benchmark models are created that cover the qualitatively different signatures and a benchmark multiregion search strategy is presented that covers these models.Comment: 30 pages, 8 Figures, 3 Tables. Version accepted at JHEP. Minor changes. Added figur