Prerit Jaiswal

Excluding electroweak baryogenesis in the MSSM

A bstractIn the context of the MSSM the Light Stop Scenario (LSS) is the only region of parameter space that allows for successful Electroweak Baryogenesis (EWBG). This possibility is very phenomenologically attractive, since it allows for the direct production of light stops and could be tested at the LHC. The ATLAS and CMS experiments have recently supplied tantalizing hints for a Higgs boson with a mass of ≈ 125 GeV. This Higgs mass severely restricts the parameter space of the LSS, and we discuss the specific predictions made for EWBG in the MSSM. Combining data from all the available ATLAS and CMS Higgs searches reveals a tension with the predictions of EWBG even at this early stage. This allows us to exclude EWBG in the MSSM at greater than (90) 98% confidence level in the (non-)decoupling limit, by examining correlations between different Higgs decay channels. We also examine the exclusion without the assumption of a ≈ 125 GeV Higgs. The Higgs searches are still highly constraining, excluding the entire EWBG parameter space at greater than 90% CL except for a small window of mh ≈ 117-119 GeV.

Explanation of the

The WW production cross section measured at the LHC has been consistently exhibiting a mild excess beyond the SM prediction, in both ATLAS and CMS at both 7-TeV and 8-TeV runs. We provide an explanation of the excess in terms of resummation of large logarithms that arise from a jet-veto condition, i.e., the rejection of high-pT jets with pT > pT(veto) that is imposed in the experimental analyses to reduce backgrounds. Jet veto introduces a second mass scale pT(veto) to the problem in addition to the invariant mass of the WW pair. This gives rise to large logarithms of the ratio of the two scales that need to be resummed. Such resummation may not be properly accounted for by the Monte Carlo simulations used in the ATLAS and CMS studies. Those logarithms are also accompanied by large pi^2 terms when the standard, positive sign is chosen for the squared renormalization scale. We analytically resum the large logarithms including the pi^2 terms in the framework of soft collinear effective theory (SCET), and demonstrate that the SCET calculation not only reduces the scale uncertainties of the SM prediction significantly but also renders the theory prediction well compatible with the experiment. We find that resummation of the large logarithms and that of the pi^2 terms are both comparably important.

WW

We investigate the spectacular collider signatures of macroscopically displaced, neutral particles that decay to Higgs bosons and missing energy. We show that such long-lived particles arise naturally in a very minimal extension of the Standard Model with only two new fermions with electroweak interactions. The lifetime of the long-lived neutral particles can range from 10^{-2} mm to 10^6 mm. In some regions of the parameter space, the exotic signals would have already been selected by the ATLAS and CMS triggers in their 7 and 8 TeV runs, hence hiding in the existing data. We also discuss the possibility of explaining the mild anomalies observed in the diphoton Higgs channel and the WW production at the LHC.

excess at the LHC by jet-veto resummation

The associated production of a Higgs boson with a b quark is a discovery channel for the lightest MSSM neutral Higgs boson. We consider the SUSY QCD contributions from squarks and gluinos and discuss the decoupling properties of these effects. A detailed comparison of our exact order(alpha_s) results with those of a widely used effective Lagrangian approach, the \Delta_b approximation, is presented. The \Delta_b approximation is shown to accurately reproduce the exact one-loop SQCD result to within a few percent over a wide range of parameter space.

Higgs Production Amidst the LHC Detector

The search for a new source of CP violation is one of the most important endeavors in particle physics. A particularly interesting way to perform this search is to probe the CP phase in the

Prospect for measuring the CP phase in the

h\tau\tau

coupling at the LHC

coupling, as the phase is currently completely unconstrained by all existing data. Recently, a novel variable