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Charged Higgs and SUSY searches at CDF

Description: We present recent results of supersymmetric (SUSY) particle searches at the Collider Detector at Fermilab. These include searches for squarks, gluinos, charginos, and neutralinos using the {ital E}{sub T}-multijet, like-sign dilepton, and trilepton SUSY signatures. Results from a charged Higgs search using the hadronic decays of the tau lepton are also presented.
Date: July 1996
Creator: Loomis, C.
Partner: UNT Libraries Government Documents Department

Search for charged Higgs bosons in CDF

Description: We present results of a direct search for charged Higgs production from {ital p}{ital {anti p}} collisions at {radical}s = 1.8 TeV at Fermilab`s Tevatron collider using the CDF detector. An expanded Higgs sector containing charged Higgs bosons is a persistent feature of candidate theories to replace the Standard Model. The minimal supersymmetric extension of the Standard Model, for example predicts that the dominant decay mode of the top quark is {ital t} {r_arrow} H{sup +}{ital b} {r_arrow} {tau}{sup +} {ital vb} for large values of tan {Beta}. We use the hadronic decays of the tau lepton in this channel to exclude charged Higgs bosons with M{sub H{sup {+-}}} {lt} 140 GeV/c{sup 2} for large tan{Beta}.
Date: August 1, 1996
Creator: Loomis, C.
Partner: UNT Libraries Government Documents Department

Searching for doubly-charged Higgs bosons at future colliders

Description: Doubly-charged Higgs bosons ({Delta}{sup --}/{Delta}{sup ++}) appear in several extensions to the Standard Model and can be relatively light. We review the theoretical motivation for these states and present a study of the discovery reach in future runs of the Fermilab Tevatron for pair-produced doubly-charged Higgs bosons decaying to like-sign lepton pairs. We also comment on the discovery potential at other future colliders. 16 refs., 3 figs., 1 tab.
Date: October 1, 1996
Creator: Gunion, J.F.; Loomis, C. & Pitts, K.T.
Partner: UNT Libraries Government Documents Department

STRUCTURE FUNCTION ANALYSIS OF LONG-TERM QUASAR VARIABILITY

Description: In our second paper on long-term quasar variability, we employ a much larger database of quasars than in de Vries, Becker & White. This expanded sample, containing 35,165 quasars from the Sloan Digital Sky Survey Data Release 2, and 6,413 additional quasars in the same area of the sky taken from the 2dF QSO Redshift Survey, allows us to significantly improve on our earlier conclusions. As before, all the historic quasar photometry has been calibrated onto the SDSS scale by using large numbers of calibration stars around each quasar position. We find the following: (1) the outbursts have an asymmetric light-curve profile, with a fast-rise, slow-decline shape; this argues against a scenario in which micro-lensing events along the line-of-sight to the quasars are dominating the long-term variations in quasars; (2) there is no turnover in the Structure Function of the quasars up to time-scales of {approx}40 years, and the increase in variability with increasing time-lags is monotonic and constant; and consequently, (3) there is not a single preferred characteristic outburst time-scale for the quasars, but most likely a continuum of outburst time-scales, (4) the magnitude of the quasar variability is a function of wavelength: variability increases toward the blue part of the spectrum, (5) high-luminosity quasars vary less than low-luminosity quasars, consistent with a scenario in which variations have limited absolute magnitude. Based on this, we conclude that quasar variability is intrinsic to the Active Galactic Nucleus, is caused by chromatic outbursts/flares with a limited luminosity range and varying time-scales, and which have an overall asymmetric light-curve shape. Currently the model that has the most promise of fitting the observations is based on accretion disk instabilities.
Date: November 15, 2004
Creator: de Vries, W; Becker, R; White, R & Loomis, C
Partner: UNT Libraries Government Documents Department