Odd Tracks at Hadron Colliders

New physics that exhibits irregular tracks such as kinks, intermittent hits or decay in flight may easily be missed at hadron colliders. We demonstrate this by studying viable models of light, O(10 GeV), colored particles that decay predominantly inside the tracker. Such particles can be produced at staggering rates, and yet may not be identified or even triggered on at the LHC, unless specifically searched for. In addition, the models we study provide an explanation for the original measurement of the anomalous charged track distribution by CDF. The presence of irregular tracks in these models reconcile that measurement with the subsequent reanalysis and the null results of ATLAS and CMS. Our study clearly illustrates the need for a comprehensive study of irregular tracks at the LHC.Comment: 6 pages, 1 figur

Transverse momentum resummation effects in W^+W^- measurements

The W^+W^- cross section has remained one of the most consistently discrepant channels compared to SM predictions at the LHC, measured by both ATLAS and CMS at 7 and 8 TeV. Developing a better modeling of this channel is crucial to understanding properties of the Higgs and potential new physics. In this paper we investigate the effects of NNLL transverse momentum resummation in measuring the W^+W^- cross section. In the formalism we employ, transverse momentum resummation does not change the total inclusive cross section, but gives a more accurate prediction for the p_T distribution of the diboson system. By re-weighting the p_T distribution of events produced by Monte Carlo generators, we find a systematic shift that decreases the experimental discrepancy with the SM prediction by approximately 3-7% depending on the MC generator and parton shower used. The primary effect comes from the jet veto cut used by both experiments. We comment on the connections to jet veto resummation, and other methods the experiments can use to test this effect. We also discuss the correlation of resummation effects in this channel with other diboson channels. Ultimately p_T resummation improves the agreement between the SM and experimental measurements for most generators, but does not account for the measured ~20% difference with the SM and further investigations into this channel are needed.Comment: 21 pages, 9 figures, v2: minor changes/refs update

Top Partners at the LHC: Spin and Mass Measurement

If one takes naturalness seriously and also assumes a weakly coupled extension of the Standard Model (SM) then there are predictions for phenomenology that can be inferred in a model independent framework. The first such prediction is that there must be some colored particle with mass O(TeV) that cancels the top loop contribution to the quadratic divergence of the Higgs mass. In this paper we begin a model independent analysis of the phenomenology of this "top partner," t'. We make one additional assumption that it is odd under a parity which is responsible for the stability of a WIMP dark matter candidate, N. We focus on three questions to be explored at the LHC: discovery opportunities, mass determination, and spin determination of this top partner. We find that within a certain region of masses for the t' and N, t'\bar{t'} is easily discovered in the t\bar{t}+2N decay with the tops decaying fully hadronically. We show that without having to rely on other channels for new physics that for a a given t' spin the masses of t' and N can be measured using kinematic information (e.g. average MET or H_T) and total cross section. A degeneracy due to the spin remains, but with several hundred inverse fb of luminosity we demonstrate potentially useful new methods for determining the t' spin over a wide range of masses. Our methods could be useful for distinguishing supersymmetric and non-supersymmetric models.Comment: 28 pages, 5 figure

Testing Electroweak Baryogenesis with Future Colliders

Electroweak Baryogenesis (EWBG) is a compelling scenario for explaining the matter-antimatter asymmetry in the universe. Its connection to the electroweak phase transition makes it inherently testable. However, completely excluding this scenario can seem difficult in practice, due to the sheer number of proposed models. We investigate the possibility of postulating a "no-lose" theorem for testing EWBG in future e+e- or hadron colliders. As a first step we focus on a factorized picture of EWBG which separates the sources of a stronger phase transition from those that provide new sources of CP violation. We then construct a "nightmare scenario" that generates a strong first-order phase transition as required by EWBG, but is very difficult to test experimentally. We show that a 100 TeV hadron collider is both necessary and possibly sufficient for testing the parameter space of the nightmare scenario that is consistent with EWBG.Comment: 26 pages + references, 10 figures. Fixed minor typos, updated TLEP and 100 TeV projections. Conclusions unchange