Article

Searching for Invisible and Almost Invisible Particles at e^+e^- Colliders

Physical Review Letters (Impact Factor: 7.73). 12/1995; 76(12). DOI: 10.1103/PhysRevLett.76.2002
Source: arXiv

ABSTRACT We explore the techniques, cross sections and expected signal significance
for detecting invisible and almost invisible particles at LEP2 and the NLC by
means of a hard photon tag. Examples from supersymmetry include the lightest
chargino and second lightest neutralino when their masses are nearly the same
as that of the lightest neutralino (the LSP), and invisibly decaying
sneutrinos. The importance of particular features of the detectors is
discussed, instrumentation for vetoing a fast e^+ or e^- in the beam hole being
especially crucial.

0 Bookmarks
 · 
79 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The possibility of detecting the signature of a nearly invisible charged wino (χ~+/-) decaying into a soft pion and the LSP (χ~10), predicted by the Anomaly Mediated Symmetry Breaking model, via the process e+e--->γχ~+χ~- at the Next Linear Collider has been explored. Using the recently proposed bounds on slepton and wino masses derived from the condition of stability of the electroweak symmetry breaking vacuum and employing some standard kinematical cuts to suppress the background, we find that almost the whole of the allowed parameter space with the slepton mass less than 1 TeV, can be probed at /sqrt(s)=500 GeV. Determination of the slepton and the chargino masses from this signal is a distinct possibility. Any violation of the above mass bound will suggest that the standard vacuum is unstable and we are living in a false vacuum.
    Physics Letters B 07/2001; 513(1-2):130-136. · 4.57 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We show how the spectrum of the minimal anomaly mediated supersymmetry breaking model can be constrained from the condition that the electroweak symmetry breaking minimum of the scalar potential is the deepest point in the field space. Applying the current experimental bounds and scanning over the whole parameter space, we rule out selectrons below 378 GeV and staus below 269 GeV, the numbers having a modest uncertainty. We also find a new upper bound on the W-ino-like chargino mass for a given slepton mass. This rules out the possibility of slepton pair production at ongoing or upcoming colliders such as the Fermilab Tevatron or the Next Linear Collider at s=500 GeV, where pair production of charginos may be the only available signal.
    Physical Review D 11/2001; 64(9):95016-. · 4.69 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: It is shown that if the charginos decay into very soft leptons or hadrons + E/ due to degeneracy or near degeneracy with the lightest supersymmetric particle or the sneutrino, the observability of the recently proposed signal via the single photon (+ soft particles) + E/ channel crucially depends on the magnitude of the ν~ mass due to destructive interferences in the matrix element squared. If the ν~'s and, consequently, left sleptons are relatively light, the size of the signal, previously computed in the limit mν~-->∞ only, is drastically reduced. We present the formula for the signal cross section in a model independent way and discuss the observability of the signal at CERN LEP 192 and NLC energies.
    Physical Review D 03/1999; 59(5):55019-. · 4.69 Impact Factor

Full-text (2 Sources)

Download
0 Downloads
Available from