3,688 research outputs found
Z-prime Gauge Bosons at the Tevatron
We study the discovery potential of the Tevatron for a Z-prime gauge boson.
We introduce a parametrization of the Z-prime signal which provides a
convenient bridge between collider searches and specific Z-prime models. The
cross section for p pbar -> Z-prime X -> l^+ l^- X depends primarily on the
Z-prime mass and the Z-prime decay branching fraction into leptons times the
average square coupling to up and down quarks. If the quark and lepton masses
are generated as in the standard model, then the Z-prime bosons accessible at
the Tevatron must couple to fermions proportionally to a linear combination of
baryon and lepton numbers in order to avoid the limits on Z--Z-prime mixing.
More generally, we present several families of U(1) extensions of the standard
model that include as special cases many of the Z-prime models discussed in the
literature. Typically, the CDF and D0 experiments are expected to probe
Z-prime-fermion couplings down to 0.1 for Z-prime masses in the 500--800 GeV
range, which in various models would substantially improve the limits set by
the LEP experiments.Comment: 34 pages, 13 figure
Single Queue Attended by Alternative Servers with Changeover Times
A single queue is serviced by two servers alternately, in alternate busy periods. A changeover time is required whenever the servers are replaced. In this model, the changeover time of a server is initiated as soon as one server completes the services of the units waiting before him namely at the end of his busy period. It may be noted that the empty state of the system is never reached. A comparison of this model with the model with empty state has been done
D-Terms, Unification, and the Higgs Mass
We study gauge extensions of the MSSM that contain non-decoupling D-terms,
which contribute to the Higgs boson mass. These models naturally maintain gauge
coupling unification and raise the Higgs mass without fine-tuning. Unification
constrains the structure of the gauge extensions, limiting the Higgs mass in
these models to roughly less than 150 GeV. The D-terms contribute to the Higgs
mass only if the extended gauge symmetry is broken at energies of a few TeV,
leading to new heavy gauge bosons in this mass range.Comment: 30+1 pages, 7 figure
Alternate Servers with Set up Times
The paper analyzes a queueing model consisting of a single queue serviced by two servers alternately. A change over time is required when one server is replaced by another. In a busy period, only one server is servicing and when it empties the queue, the second server takes over and thus the two servers work alternately. The actual service after the change over time of the particular server under operation
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