Howard Baer

Squark decays into gauginos at the pp collider

Conventional analyses of missing pT events due to squark production at the CERN pp collider assume q → qγ decays dominate. In principle, the monojet and dijet cross sections could be reduced by competition from q → qW± and q → qZ0 decays. We compute this reduction factor for two mass scenarios: mq > mW > mol and ml ≈ mq > mW. The monojet and dijet cross sections for squarks light enough to be observed in present collider experiments are reduced by no more than 55%, while there may exist an observable cross section for jet(s) + charged lepton(s) + missing pT events. Thus the lower bounds on mq usually derived from q → qγ decays remain valid.

Component formulae for hadroproduction of left-and right-handed squarks

We present differential cross section formulae for left-left, right-right, and left-right squark pair production in hadronic collisions, for unequal left- and right-handed squark masses. These formulae are useful in calculations involving weak decays of squarks to winos and zinos.

Multilepton signals from W± and Z0 decays to gauginos at pp colliders

Abstract One of the interpretations of the CERN monojet events requires the squark mass to be about 40–50 GeV implying a slepton mass around 20–30 GeV in a wide variety of models. If, in this scenario, the wino (W) and zino (Z) masses are light enough so that the decays W → WZ and Z → WW are allowed, a variety of spectacular dilepton and trilepton signals are expected to occur at a substantial rate and with negligible backgrounds. We present rates and distributions for these multilepton events which may be used to pin down the gaugino masses.

SUPERSYMMETRY AT BAY

Abstract If the squark mass m q is O(40) GeV, as suggested by one interpretation of the CERN pp collider data, then one expects slepton masses m l ∼ O(20−30) GeV in a wide class of models. Sleptons with such masses would be produced copiously in W → l ν and Z 0 → l + l − decays. We present rates and distributions for these processes, in corporating detector resolutions and experimental cuts. We show how the supersymmetric signals (especially for Z 0 → l + l − ) can easily be distinguished from the standard model backgrounds.

Implications of the T Quark Signal for Stop Squarks and Charged Higgs Bosons

Abstract If there exists a stop squark of a charged Higgs boson lighter than the t-quark, so that the top quark decays dominantly via the two-body mode t → t γ or t → bh, the standard model t-quark signal may be expected to be modified. This difference is discussed for various Higgs boson, stop squark and photino masses. The UA1 data seem to rule out a Higgs boson with a mass less than (mt − mb). A stop squark with mass m t less than m t − m γ also appears unlikely. The po ssibility of detecting heavy charged Higgs at SLC or LEP is also discussed.

Consequences of Models for Monojet Events From

Abstract Three models for monojet events with large missing transverse momentum observed at the CERN p p collider are studied: (i) Z decay into a neutral lepton pair where one of the pair decays within the detector while the other escapes, (ii) Z decay into two distinct neutral scalars where the lighter one is long lived, and (iii) Z decay into two distinct higgsinos where the lighter one is long lived. The first model necessarily gives observable decay in flight signals. Consequences of the latter two models are investigated in both p p collisions at CERN and e+e− annihilation at PETRA/PEP energies.