Spin correlations in $e^+e^-\to 4$ jets

Abstract

Existence of discrepancies between experimental data and Monte Carlo predictions for angular distributions in four-jet production via e + e − annihilation has been known for some time at LEP1. As such QCD processes constitute significant backgrounds to e + e − → W + W − → 4-jet production at LEP2, we consider the possibility that an erroneous modelling of the helicity structure of the finalstate partons could affect the accuracy of experimental measurements of the W ± boson parameters.

Charged Higgs boson detection in theτνdecay mode at future linear colliders

“…An example of such a combination, although performed for the SM Higgs boson searches at LHC, can be found in [37]. Concluding the above summary of previous results, the most competitive search channel to the study presented in this work is the one studied in [27,28] whose results are compared in detail with those of this study in a separated section.…”

“…Therefore the analysis is based on the on-shell production of charged Higgs bosons and the possible off-shell production is not considered here as it may not change the results very much. This is an expectation inspired from [27,28].…”

“…However it was shown that the cross section of this process is a fraction of femtobarn leading to no hope for observation of this channel. In [27,28], the single heavy charged Higgs production through e + e − → τ νH + was analyzed. It was shown that the charged Higgs pair production is increased when including off-shell effects and leads to more promising results.…”

“…Since then more attention has been paid on single charged Higgs production when a heavy charged Higgs is the target. However results from [27,28] show that including off-shell effects, the 5σ contour would be extended by only about 10 GeV compared to the case of on-shell charged Higgs pair production. The eν e H ± process was also studied in [29], but it was concluded that the signal cross section is below 0.01 f b even for the very low tan β values.…”

“…It is reasonable to use the charged Higgs decay to top quarks when a heavy charged Higgs is being analyzed and that is in fact was has been done in [27,28]. The charged Higgs branching ratio of decay to top quarks starts to be dominant when the charged Higgs mass goes beyond that of the top quark, allowing the charged Higgs boson to decay to a real on-shell top quark.…”