Production of Kaluza-Klein States at Future Colliders

Perturbative breaking of supersymmetry in four-dimensional string theories predict in general the existence of new large dimensions at the TeV scale. Such large dimensions lie in a domain of energies accessible to particle accelerators. Their main signature is the production of Kaluza-Klein excitations which can be detected at future colliders. We study this possibility for hadron colliders (TEVATRON, LHC) and $e^+ e^-$ colliders (LEP-200, NLC-500).Comment: 13 pages, LATEX, 4 postscript figures appended at the end, CPTH-A293.0294 and IEM-FT-84/9

Heavy neutrino signals at large hadron colliders

We study the LHC discovery potential for heavy Majorana neutrino singlets in the process pp -> W+ -> l+ N -> l+ l+ jj (l=e,mu) plus its charge conjugate. With a fast detector simulation we show that backgrounds involving two like-sign charged leptons are not negligible and, moreover, they cannot be eliminated with simple sequential kinematical cuts. Using a likelihood analysis it is shown that, for heavy neutrinos coupling only to the muon, LHC has 5 sigma sensitivity for masses up to 200 GeV in the final state mu+- mu+- jj. This reduction in sensitivity, compared to previous parton-level estimates, is driven by the ~ 10^2-10^3 times larger background. Limits are also provided for e+- e+- jj and e+- mu+- jj final states, as well as for Tevatron. For heavy Dirac neutrinos the prospects are worse because backgrounds involving two opposite charge leptons are much larger. For this case, we study the observability of the lepton flavour violating signal e+- mu-+ jj. As a by-product of our analysis, heavy neutrino production has been implemented within the ALPGEN framework.Comment: Latex 36 pages, 49 PS figures. Major extension incorporating analysis for e+- e+-, e+- mu+- and e+- mu-+ final states. Final version to appear in JHE

With four Standard Model families, the LHC could discover the Higgs boson with a few fb^-1

The existence of a 4th SM family would produce a large enhancement of the gluon fusion channel of Higgs boson production at hadron colliders. In this case, the SM Higgs boson could be seen at the CERN Large Hadron Collider (LHC) via the golden mode (H->4l) with an integral luminosity of only a few fb^-1.Comment: 7 pages, 2 figures, 2 tables, references updated in v

Future Colliders

Future high-energy colliders are discussed, in particular linear e+ e- colliders, mu+ mu- colliders and hadron colliders. The energies of the e+ e- colliders are larger than that of the existing e+e- collider LEP. The energies of the very large hadron colliders are larger than that of the LHC which is being constructed at CERN. Two mu+mu- colliders at 100 and 3000 GeV are included. For all these colliders, parameter list, topics of R&D, and progress with component tests are discussed

Physics at Future Hadron Colliders

We discuss the physics opportunities and detector challenges at future hadron colliders. As guidelines for energies and luminosities we use the proposed luminosity and/or energy upgrade of the LHC (SLHC), and the Fermilab design of a Very Large Hadron Collider (VLHC). We illustrate the physics capabilities of future hadron colliders for a variety of new physics scenarios (supersymmetry, strong electroweak symmetry breaking, new gauge bosons, compositeness and extra dimensions). We also investigate the prospects of doing precision Higgs physics studies at such a machine, and list selected Standard Model physics rates.We discuss the physics opportunities and detector challenges at future hadron colliders. As guidelines for energies and luminosities we use the proposed luminosity and/or energy upgrade of the LHC (SLHC), and the Fermilab design of a Very Large Hadron Collider (VLHC). We illustrate the physics capabilities of future hadron colliders for a variety of new physics scenarios (supersymmetry, strong electroweak symmetry breaking, new gauge bosons, compositeness and extra dimensions). We also investigate the prospects of doing precision Higgs physics studies at such a machine, and list selected Standard Model physics rates

Triggering at High Luminosity Colliders

This article discusses the techniques used to select online promising events at high energy and high luminosity colliders. After a brief introduction, explaining some general aspects of triggering, the more specific implementation options for well established machines like the Tevatron and Large Hadron Collider are presented. An outlook on what difficulties need to be met is given when designing trigger systems at the Super Large Hadron Collider, or at the International Linear ColliderComment: Accepted for publication in New Journal of Physic