Monte Carlo simulation of baryon and lepton number violating processes at high energies

Abstract

We report results obtained with the first complete event generator for electroweak baryon and lepton number violating interactions at supercolliders. Typical events contain of the order of 50 electroweak gauge bosons, some Higgs bosons and quarks and leptons of all generations. There is still great uncertainty about the expected rate, but an event generator is needed in any case to establish what experimental limits can be placed on the cross section, and to determine whether, even if such spectacular events are seen, baryon and/or lepton number violation can be conclusively demonstrated. We find that baryon number violation would be very difficult to establish, but lepton number violation can be seen provided at least a few hundred L violating events are available with good electron or muon identification in the energy range 10 GeV to 1 TeV. The event generator, which takes the form of a package (HERBVI) interfacing to the existing simulation program HERWIG, should be useful for the coming period of detailed experiment design for the Large Hadron Collider (LHC) at CERN.

Parton-shower simulations of R-parity violating supersymmetric models

“…This is exactly the same result obtained in [29], in the context of baryon number violation in the Standard Model, except that the massless radiation functions of their paper are now replaced by the massive functions here. This leads to the following approach for treating the soft gluon radiation from this process.…”

General-purpose event generators for LHC physics

“…This presents a problem both in the selection of the colour partners for the parton shower evolution and later in the hadronization stage. The simulation of these models, with the angular-ordered parton shower and cluster hadronization model [230,231] and in the string model [174] (see Section 8.2), has been studied in detail with the selection of the colour partners for the perturbative radiation being done at random from among the potential partners, and after the shower a special treatment of three partons colour connected to the junction. Secondly, in hidden valley models [232,233] there are particles that are charged under a new strongly interacting gauge group.…”

Search for sphalerons in proton-proton collisions

“…The normalized invariant-mass distributions for the observable final-state particles are shown in figure 3, for LHC collisions at 13 and 14 TeV (left panel, blue and red histograms, respectively) and for future colliders at 33 and 100 TeV (right panel, green and pink histograms, respectively), for our nominal choices E Sph = 9 TeV, c = 2 and p = 1. As seen in 5 There are suggestions that the baryon and lepton number violating processes are enhanced if fermions are produced associated with many O(1/αW ) electroweak bosons [5,6,[24][25][26]. We leave the investigation of this possibility for future work.…”