b -> s Transitions: A New Frontier for Indirect SUSY Searches

The present unitarity triangle fit, whose essential input is represented by the s to d and b to d transition processes, fully agrees with the SM. However, most of the phenomena involving b to s transitions are still largely unexplored and hence b to s phenomenology still constitutes a place for new physics manifestations, in spite of the tremendous experimental and theoretical progress on B to X_s gamma. We perform a systematic study of the CP conserving and violating SUSY contributions to b to s processes in a generic MSSM. We consider gluino exchange contributions including NLO QCD corrections and lattice hadronic matrix elements for Delta B = 2 and Delta B = 1 processes. We take into account all available experimental information on processes involving b to s transitions (B to X_s gamma, B to X_s l^+ l^- and the lower bound on the B_s - bar B_s mass difference Delta M_s). We study the correlations among the relevant observables under scrutiny at present or in a not too far future: Delta M_s and the amount of CP violation in B to phi K_s, B_s to J/psi phi, B to X_s gamma. In particular we discuss the recent data by BaBar and BELLE on the time-dependent CP asymmetry in the decay B to phi K_s which suggest a deviation from the SM expectation. Our results show that the processes involving b to s transitions represent a splendid opportunity to constrain different MSSM realizations, and, even more important, that they offer concrete prospects to exhibit SUSY signals at B factories and hadron colliders in spite of all the past frustration in FCNC searches of new physics hints.Comment: 20 pages, 8 figures. Bug in the code corrected, figures for RL and RL=RR cases and some conclusions change

Worries and Hopes for SUSY in CKM Physics: The b to s Example

We discuss the twofold role of flavor and CP violation as a constraint in model building and as a signal of SUSY. Considering as an example b to s transitions, we analyze present bounds on SUSY parameters, discuss possible deviations from SM predictions in Bd and Bs physics and present strategies to reveal SUSY signals in present and future experiments in the CKM domain.Comment: Invited talks given by A. Masiero and L. Silvestrini at the Workshop on the CKM Unitarity Triangle, IPPP Durham, April 2003 (eConf C0304052). 9 pages, 5 figure

Probing Supersymmetric Flavor Models with ϵ′/ϵ\epsilon'/\epsilon

We discuss the supersymmetric contribution to $\epsilon'/\epsilon$ in various supersymmetric flavor models. We find that in alignment models the supersymmetric contribution could be significant while in heavy squark models it is expected to be small. The situation is particularly interesting in models that solve the flavor problems by either of the above mechanisms and the remaining CP problems by means of approximate CP, that is, all CP violating phases are small. In such models, the standard model contributions cannot account for $\epsilon'/\epsilon$ and a failure of the supersymmetric contributions to do so would exclude the model. In models of alignment and approximate CP, the supersymmetric contributions can account for $\epsilon'/\epsilon$ only if both the supersymmetric model parameters and the hadronic parameters assume rather extreme values. Such models are then strongly disfavored by the $\epsilon'/\epsilon$ measurements. Models of heavy squarks and approximate CP are excluded.Comment: 16 pages, harvmac. v2: We added a discussion of the intriguing implications that would follow if a recent lattice result is confirme

SUSY in Rare and CP-Violating B Decays

In this talk we discuss rare B decays (b -> s gamma, b -> s g, b -> s l^+ l^-), B-\bar{B} oscillations and CP violation in B physics in the context of low-energy SUSY. We outline the variety of predictions that arise according to the choice of the SUSY extension ranging from what we call the "minimal" version of the MSSM to models without flavour universality or with broken R-parity. In particular, we provide a model-independent parameterization of the SUSY FCNC and CP-violating effects which is useful in tackling the problem in generic low-energy SUSY. We show how rare B decays and CP violation in B-decay amplitudes may be complementary to direct SUSY searches at colliders, in particular for what concerns extensions of the most restrictive version of the MSSM.Comment: LaTeX, 13 pages. Talk given by A. Masiero at the 2nd International Conference on B Physics and CP Violation (BCONF 97), Honolulu, HI, 24-28 Mar 199

Pre-LHC SUSY Searches: an Overview

We discuss the prospects for searches of low-energy supersymmetry in the time interval separating us from the advent of LHC. In this period of time "indirect" searches may play a very relevant role. We refer to manifestations of supersymmetry in flavour changing neutral current and CP violating phenomena and to signals of the lightest supersymmetric particle in searches of dark matter. In the first part of the talk we critically review the status of the minimal supersymmetric model to discuss the chances that direct and indirect supersymmetric searches may have before the LHC start. In the second part we point out what we consider to be the most promising grounds where departures from the standard model prediction may signal the presence of new physics, possibly of supersymmetric nature. We argue that the often invoked complementarity of direct and indirect searches of low-energy supersymmetry is becoming even more true in the pre-LHC era.Comment: LaTeX, 23 pages, invited talks given by A. Masiero at the Tropical Workshop on Particle Physics and Cosmology and at the Second Latin American Symposium on High Energy Physics, Puerto Rico, April 1-10, 199

Fermion Virtual Effects in e+e−−>W+W−e^+ e^- -> W^+ W^- Cross Section

We analyse the contribution of new heavy virtual fermions to the $e^+e^- \rightarrow W^+W^-$ cross section. We find that there exists a relevant interplay between trilinear and bilinear oblique corrections. The result strongly depends on the chiral or vector--like nature of the new fermions. As for the chiral case we consider sequential fermions: one obtains substantial deviation from the Standard model prediction, making the effect possibly detectable at $\sqrt{s}=500$ or $1000$ GeV linear colliders. As an example for the vector--like case we take a SUSY extension with heavy charginos and neutralinos: due to cancellation, the final effect turns out to be negligible.Comment: uuencoded, gz-compressed, tar-ed file. 8 pages, 4 EPS figures, uses EPSFIG.ST

Two-body nonleptonic B decays in the Standard Model and beyond

We briefly discuss the phenomenology of B to pi pi, B to K pi and B to phi K decays in the Standard Model and in Supersymmetry.Comment: 7 pages, 2 figures, uses moriond.sty. Talk given by L. Silvestrini at the XXXIXth Rencontres de Moriond on ElectroWeak Interactions and Unified Theories, La Thuile, Aosta Valley, Italy, March 21st-28th 200