Impact of bosonic decays on the search for stau_2 and tau-sneutrino

We perform a detailed study of the decays of the heavier tau slepton (stau_2) and tau-sneutrino (snu_tau) in the Minimal Supersymmetric Standard Model (MSSM). We show that the decays into Higgs or gauge bosons, i.e. stau_2 -> stau_1 + (h^0, H^0, A^0 or Z^0), stau_2 -> snu_tau + (H^- or W^-), and snu_tau -> stau_1 + (H^+ or W^+), can be very important due to the sizable tau Yukawa coupling and large mixing parameters of stau. Compared to the decays into fermions, such as stau_2 -> tau + neutralino_i and stau_2 -> nu_tau + chargino_j^-, these bosonic decay modes can have significantly different decay distributions. This could have an important influence on the search for stau_2 and snu_tau and the determination of the MSSM parameters at future colliders.Comment: 12 pages, 3 figures, LaTeX2

Higgs Particle Decays in Supersymmetry

We present a detailed study of the decays of the Higgs bosons $H^+$, $H^0$, and $A^0$ within the Minimal Supersymmetric Standard Model including SUSY--QCD corrections. We find that the supersymmetric modes $\tilde t \bar{\tilde b}$ ($\tilde t \bar{\tilde t}$, and for large $\tan\beta$ $\tilde b \bar{\tilde b}$) can dominate the $H^+$ ($H^0$, $A^0$) decays in a wide range of the model parameters due to the large Yukawa couplings and mixings of $\tilde t$ and $\tilde b$. Compared to the conventional modes $H^+ \to \tau^+ \nu_{\tau}, t \bar b$, and $H^0, A^0 \to t \bar t, b \bar b$, the supersymmetric modes can have an important impact on the Higgs boson searches at future colliders.Comment: 6 pages, LaTeX, 2 figures, uses epsfig, format changed to plain article, contents unchange

High-intensity two-frequency photoassociation spectroscopy of a weakly bound molecular state: theory and experiment

We investigate two-frequency photoassociation of a weakly bound molecular state, focusing on a regime where the ac Stark shift is comparable to the halo-state energy. In this "high-intensity" regime, we observe features absent in low-intensity two-frequency photoassociation. We experimentally measure the spectra of $^{86}$Sr atoms coupled to the least bound state of the $^{86}$Sr$_2$ ground electronic channel through an intermediate electronically excited molecular state. We compare the spectra to a simple three-level model that includes a two-frequency drive on each leg of the transition. With numerical solution of the time-dependent Schrodinger equation, we show that this model accurately captures (1) the existence of experimentally observed satellite peaks that arise from nonlinear processes, (2) the locations of the two-photon peak in the spectrum, including ac Stark shifts, and (3) in some cases, spectral lineshapes. To better understand these numerical results, we develop an approximate treatment of this model, based on Floquet and perturbation theory, that gives simple formulas that accurately capture the halo-state energies. We expect these expressions to be valuable tools to analyze and guide future two-frequency photoassociation experiments.Comment: 12 pages, 7 figure