Top off the unparticle

The existence of an exactly scale invariant sector possessing a non-trivial infrared fixed point at a higher energy scale and its possible communication with the Standard Model particles through a heavy messenger sector has been shown to lead to curious unparticle effects. We demonstrate that top physics at the Tevatron can already constrain such theories. We also consider possible improvements at the LHC and delineate some striking signatures.Comment: 5 page

Little Higgs after the little one

At the LHC, the Littlest Higgs Model with $T$-parity is characterised by various production channels. If the $T$-odd quarks are heavier than the exotic partners of the $W$ and the $Z$, then associated production can be as important as the pair-production of the former. Studying both, we look for final states comprising at least one lepton, jets and missing transverse energy. We consider all the SM processes that could conspire to contribute as background to our signals, and perform a full detector level simulation of the signal and background to estimate the discovery potential at the current run as well as at the scheduled upgrade of the LHC. We also show that, for one of the channels, the reconstruction of two tagged $b$-jets at the Higgs mass $(M_h = 125~{\rm GeV})$ provides us with an unambiguous hint for this model.Comment: 22 pages, 3 captioned figures, 8 Tables; minor modifications, version published in JHE

Tagging Sneutrino Resonances at a Linear Collider with Associated Photons

Sneutrino resonances at a high energy linear e+e- collider may be one of the clearest signals of supersymmetry without R-parity, especially when the R-parity-violating coupling is too small to produce observable excesses in four-fermion processes. However, there is no guarantee that the sneutrino pole will lie anywhere near the machine energy. We show that associated photon production induces the necessary energy spread, and that the resonance then leaves a clear imprint in the photon spectrum. It follows that tagging of a hard mono-energetic photon for a variety of possible final states provides a realistic method of separating sneutrino resonance signals from the Standard Model backgrounds.Comment: 25 pages, LaTeX, figures embedded, references adde