Transverse Polarization Signatures of Extra Dimensions at Linear Colliders

If significant longitudinal polarization of both the electrons and positrons becomes feasible at a future linear collider(LC), it may be possible to use spin rotators to produce transversely polarized beams. Using the transverse polarization of both beams, new azimuthal spin asymmetries can be formed which will be sensitive probes for new physics beyond the Standard Model. Here we demonstrate that these asymmetries are particularly sensitive to the exchange of Kaluza-Klein towers of gravitons, or other spin-2 fields, that are predicted to exist in higher dimensional theories which address the hierarchy problem. These new asymmetries are shown to be able to extend the search reach for such new physics by more than a factor of two, provide an additional tool for isolating the signatures for spin-2 exchange up to mass scales in excess of $10\sqrt s$, and can be used to help differentiate among the proposed solutions to the hierarchy problem below the production threshold for new particles.Comment: 22 pages, 6 figs. LaTe

Lightest-neutralino decays in R_p-violating models with dominant lambda^{prime} and lambda couplings

Decays of the lightest neutralino are studied in R_p-violating models with operators lambda^{prime} L Q D^c and lambda L L E^c involving third-generation matter fields and with dominant lambda^{prime} and lambda couplings. Generalizations to decays of the lightest neutralino induced by subdominant lambda^{prime} and lambda couplings are straightforward. Decays with the top-quark among the particles produced are considered, in addition to those with an almost massless final state. Phenomenological analyses for examples of both classes of decays are presented. No specific assumption on the composition of the lightest neutralino is made, and the formulae listed here can be easily generalized to study decays of heavier neutralinos. It has been recently pointed out that, for a sizable coupling lambda^{prime}_{333}, tau-sleptons may be copiously produced at the LHC as single supersymmetric particles, in association with top- and bottom-quark pairs. This analysis of neutralino decays is, therefore, a first step towards the reconstruction of the complete final state produced in this case.Comment: 40 pages, 11 figures, version to appear in JHE

Flavour Violation in SUSY SU(5) GUT at Large tan beta

We study flavour violation in the minimal SUSY SU(5) GUT assuming all the third generation Yukawa couplings to be due to the renormalizable physics above GUT scale. At large $\tan\beta,$ as suggested by Yukawa unification in SU(5), sizable flavour violation in the left (right) slepton (down squark) sector is induced due to renormalization effects of down type Yukawa couplings between GUT and Planck scales in addition to the flavour violation in the right slepton sector. The new flavour physics contribution to $K-\bar K,$ $B-\bar B$ mixing is small but might be of phenomenological interest in the case of $b\to s\gamma.$ The sign of the latter contribution is the same as the sign of the dominant chargino contribution, thus making the constraints on SUSY scale coming from $b\to s\gamma$ somewhat more restrictive. The most important feature of the considered scenario is the large rate of lepton flavour violation. Given the present experimental constraints, the $\mu\to e\gamma$ and $\mu-e$ conversion branching ratios are above the sensitivity of the planned experiments unless the SUSY scale is pushed above one TeV.Comment: 22 pages, 7 figure

Z' Reservation at LEP2

We consider the possibility that one extra $Z\equiv Z'$ exists with arbitrary mass and fermion couplings that do not violate (charged) lepton universality. We show that, in such a situation, a functional relationship is generated between the \underline{deviations} from the SM values of three leptonic observables of two-fermion production at future $e^+e^-$ colliders that is completely independent of the values of the $Z'$ mass and couplings. This selects a certain region in the 3-d space of the deviations that is \underline{characteristic} of the model ($Z'$ "reservation"). As a specific and relevant example, we show the picture that would emerge at LEP2 under realistic experimental conditions.Comment: 10 pages, LaTeX, 3 uuencoded ps figure

Resolved Photon Contributions to Leptoquark Production in e+e−e^+ e^- and eγe\gamma Collision

We calculate the resolved photon contribution to leptoquark production at $e\gamma$ colliders for the center of mass energies $\sqrt s=500$~GeV and 1~TeV. We also calculate the resolved photon contribution to leptoquark production at $e^+ e^-$ colliders for the center of mass energies $\sqrt{s} = 1$~and~2~TeV. In both cases we find that these contributions are considerably larger than the standard contributions considered in the literature.Comment: 9 pages (5 postscript figures in separate uuencoded file), OCIP/C 93-1

Determination of Leptoquark Properties in Polarized eγe\gamma Collisions

We study leptoquark production using polarized $e\gamma$ colliders for the center of mass energies $\sqrt s=500$~GeV and 1~TeV. We show that using polarization asymmetries the ten different types of leptoquarks listed by Buchm\"uller, R\"uckl and Wyler can be distinquished from one another for leptoquark masses essentially up to the kinematic limit of the respective colliders. Thus, if a leptoquark were discovered an $e\gamma$ collider could play a crucial role in determining its origins.Comment: 10 pages (plus 10 postscript figures submitted separately), OCIP/C 94-

Search for the lepton flavor violating decay A^0/H^0 --> tau^{+/-} mu^{+/-} at hadron colliders

In the two Higgs doublet model type III and in several other extensions of the Standard Model, there are no discrete symmetries that suppress flavor changing couplings at tree level. The experimental observation of the nu_mu -- nu_tau flavor oscillation may suggest the non-conservation of lepton number. This would lead to the decay of the type A^0/H^0 --> tau^{+/-} mu^{+/-}. We determine the present low energy limit on lepton flavor violating (LFV) couplings from the muon g-2 measurement and discuss the prospects for detecting lepton flavor violating decays at the TeVatron and at the Large Hadron Collider. The achievable bounds on the LFV coupling parameter lambda_{tau mu} are presented.Comment: 19 pages, 21 figures. Updated version takes into account the recent results on the muon g-2 measurements. Submitted to Phys. Rev. D. Added minor corrections from a refere

The Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory is a second generation water Cherenkov detector designed to determine whether the currently observed solar neutrino deficit is a result of neutrino oscillations. The detector is unique in its use of D2O as a detection medium, permitting it to make a solar model-independent test of the neutrino oscillation hypothesis by comparison of the charged- and neutral-current interaction rates. In this paper the physical properties, construction, and preliminary operation of the Sudbury Neutrino Observatory are described. Data and predicted operating parameters are provided whenever possible.Comment: 58 pages, 12 figures, submitted to Nucl. Inst. Meth. Uses elsart and epsf style files. For additional information about SNO see http://www.sno.phy.queensu.ca . This version has some new reference

Search for leptophobic Z ' bosons decaying into four-lepton final states in proton-proton collisions at root s=8 TeV

Peer reviewe