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Register a new userR-parity violation in $(t+bar t)tilde g$ production at LHC and Tevatron
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M. Chaichian
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We study the production of $(t+bar{t}) tilde{g}$ at the hadron colliders in an R-parity ($R_{p}$) violating supersymmetric model. This process provides us with information not only about $R_{p}$ violation, but may also help us in detecting the supersymmetry itself. It is possible to detect an $R_{p}$ violating signal (with single gluino production) at the future hadron colliders, such as Fermilab Tevatron Run II or CERN Large Hadron Collider (LHC), if the parameters in the supersymmetric $rlap/ R_{p}$ interactions are not too small, e.g. for $m_{tilde{g}}=1$ TeV, $lambda^{}=0.1$, still hundreds of events are produced at LHC with luminosity $30 fb^{-1}$. Even if we could not detect a signal of $ rlap/R_{p}$ in the experiment, we get stringent constraints on the heavy flavour $rlap/R_{p}$ couplings. In addition to the minimal supersymmetric standard model we have also considered some models with a heavy gluino as the lightest supersymmetric particle.
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We discuss lepton charge asymmetries in $t bar t$ and $t bar t gamma$ production at the LHC, which can be measured in the semileptonic decay channel $t bar t to W^+ b , W^- bar b to ell^+ u b , q bar q bar b$ (or the charge conjugate). Considering several variants of a new physics scenario with a light colour octet, it is seen that for $t bar t$ these asymmetries may have a sensitivity competitive with the dilepton asymmetry already measured. For $t bar t gamma$ the new leptonic asymmetries, as well as the $t bar t$ charge asymmetry, will reach their full potential with the high luminosity LHC upgrade. These asymmetries can pinpoint deviations at the $3sigma-4sigma$ level for new physics scenarios where the charge asymmetries already measured in $t bar t$ production agree within $1sigma$.
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Little Higgs models with T-parity can easily satisfy electroweak precision tests and at the same time give a stable particle which is a candidate for cold dark matter. In addition to little Higgs heavy gauge bosons, this type of models predicts a set of new T-odd fermions, which may show quite interesting signatures at colliders. We study purely leptonic signatures of T-odd leptons at the Large Hadron Collider (LHC).
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