A Fresh Look at Gauge Coupling Unification

The apparent unification of gauge couplings around 10^16 GeV is one of the strong arguments in favor of Supersymmetric extensions of the Standard Model (SM). In this contribution a new analysis, using the latest experimental data, is performed. The strong coupling alpha_s emerges as the key factor for evaluating the results of the fits, as the experimental and theoretical uncertainties in its measurements are substantially higher than for the electromagnetic and weak couplings. The present analysis pays special attention to numerical and statistical details. The results, combined with the current limits on the supersymmetric particle masses, favor a value for the SUSY scale <~ 150 GeV and for alpha_s = 0.118-0.119.Comment: 4 pages, 1 table, 1 figure; presented at the Meeting of the Division of Particles and Fields of the APS, Riverside, USA, August 200

Other BSM Searches at the LHC

A review of the discovery potential of LHC for new phenomena beyond the Standard Model (BSM) other than Supersymmetry in the early phase of running is presented. Topics covered include searches for extra dimensions in different scenarios (ADD, Randall-Sundrum, black holes ...), resonance hunting in di-lepton, di-photon and di-jet final states, searches for contact interactions, heavy stable charged particles, technicolor, etc. The strategies of the ATLAS and CMS experiments to understand the detectors and prepare them for "search" mode and the prospects for discoveries using early data are described.Comment: 9 pages, 11 figures, Invited LHC review talk at HCP2008, 19th Hadron Collider Physics Symposium 2008, Galena, IL, USA, May 27-31 200

Strong Coupling Running, Gauge Coupling Unification and the Scale of New Physics

The apparent unification of gauge couplings in Grand Unified Theories around 10$^{16}$ GeV is one of the strong arguments in favor of Supersymmetric extensions of the Standard Model. In this paper, an analysis of the measurements of the strong coupling running from the CMS experiment at the LHC is combined with a "traditional" gauge coupling unification analysis using data at the Z peak. This approach places powerful constraints on the possible scales of new physics and on the parameters around the unification scale. A supersymmetric analysis without GUT threshold corrections describes the CMS data well and provides perfect unification. The favored scales are $M_{SUSY}\ =\ 2820\ +670\ -540$GeV and$M_{GUT}\ =\ 1.05 \pm 0.06 \cdot 10^{16}$ GeV. For zero or small threshold corrections the scale of new physics may be well within LHC reach.Comment: 11 pages, 4 figures, 2 table

Sensitivity to Contact Interactions and Extra Dimensions in Di-lepton and Di-photon Channels at Future Colliders

Virtual effects from a generic description of physics beyond the Standard Model in terms of contact interactions, or from large extra dimensions will modify the observed cross sections for easy to detect final states like lepton or photon pairs, and can be used to probe scales much higher than the center-of-mass energy of the partons initiating the interactions. In this note the sensitivity reach of the Large Hadron Collider to contact interactions in the Drell-Yan channels and of a Future Linear Collider to contact interactions and extra dimensions in $e^+e^-$, $\mu^+\mu^-$ and $\gamma\gamma$ final states are studied. Experimental aspects of the measurements, systematic error effects and the evolution of the search reach with accumulated luminosity are considered.Comment: 13 pages, 2 figures, 8 tables; Contribution to LHC / LC Study Group Working Documen

Fermion-pair Production above the Z and Search for New Phenomena

A review of the measurements of hadron, flavour-tagged and lepton-pair production cross-sections and lepton-pair forward-backward asymmetries performed by the four LEP experiments ALEPH, DELPHI, L3 and OPAL at energies between 130 and 183 GeV is given. All 183 GeV results are preliminary. The searches by the four collaborations for new physics phenomena like contact interactions and compositeness, exchange of R-parity violating sneutrinos or squarks, leptoquarks or additional heavy gauge bosons Z' are summarized. No evidence for deviations from the Standard Model expectations is found and new or improved limits are derived.Comment: 6 pages, 3 figures, 2 tables, presented at the XXXIInd Rencontres de Moriond, Electroweak Interactions and Unified Theories, Les Arcs, France, March 14-21, 199

Global Analysis of Bhabha Scattering at LEP2 and Limits on Low Scale Gravity Models

A global analysis of the data on Bhabha scattering from the four LEP experiments ALEPH, DELPHI, L3 and OPAL is performed to search for effects of virtual graviton exchange in models with low scale gravity. No statistically significant deviations from the Standard Model expectations are observed and lower limits on the scale of models with large extra dimensions of $\Lambda_T = 1.077 TeV$ for $\lambda = -1$ and $\Lambda_T = 1.412 TeV$ for $\lambda = +1$ at 95% confidence level are derived.Comment: 7 pages, 1 table, 2 figures; submitted to JHE

Alternatives: Beyond SUSY Searches in CMS

The CMS discovery potential for extra dimensions in the ADD and Randall-Sundrum scenarios, for new heavy gauge bosons Z' and for contact interactions in dilepton and diphoton and dijet final states is reviewed. Special attention is paid to systematic effects both on the experimental and theory sides. The evolution of the discovery strategies and reach from LHC start-up to high accumulated luminosities are presented