Alan S. Cornell

Graviton emission from a higher-dimensional black hole

We discuss the graviton absorption probability (greybody factor) and the cross-section of a higher-dimensional Schwarzschild black hole (BH). We are motivated by the suggestion that a great many BHs may be produced at the LHC and bearing this fact in mind, for simplicity, we shall investigate the intermediate energy regime for a static Schwarzschild BH. That is, for (2M)1/(n?1)? ~ 1, where M is the mass of the black hole and ? is the energy of the emitted gravitons in (2+n)-dimensions. To find easily tractable solutions we work in the limit l >> 1, where l is the angular momentum quantum number of the graviton.

Supersymmetric effects on forward backward asymmetries of B ---> K l+ l-

Leptonic and semileptonic rare decays of B mesons provide significant (both theoretically and experimentally) signatures of any new physics beyond the standard model (SM). More specifically the decay B→Kl - l + has been theoretically observed to be very sensitive to new physics, as the forward-backward (FB) asymmetry in this decay mode vanishes in the SM. Supersymmetry, however, predicts a nonvanishing value of this asymmetry. In this work we will study the polarized lepton pair FB asymmetry, i.e. the FB asymmetry of the lepton when one (or both) final state lepton(s) are polarized. We will study these asymmetries both within the SM and for supersymmetric corrections to the SM.

SIGNATURES OF NEW PHYSICS IN DILEPTONIC B-DECAYS

Leptonic decays of B-mesons are theoretically very clean probes for testing the Standard Model (SM) and possible physics beyond it. Amongst the various leptonic decays of the B-meson, the pure dileptonic decay B → l+ l- is very important, as this mode is helicity suppressed in the SM but can be substantially enhanced in some of the models beyond the SM, such as supersymmetric (SUSY) theories and the two Higgs doublet model (2HDM). Although the purely dileptonic decay mode is helicity suppressed in the SM its associated mode B → l+ l-γ does not have the same suppression, due to the presence of γ in the final state. In this paper we will also analyze the effects of enhanced Z-penguins on these two decay modes.

Lepton polarization asymmetries for B→K*ℓ+ℓ−: a model independent approach

In this work we shall derive expressions for the single and double lepton polarization asymmetries for the exclusive decay B?K*?+??, using the most general model independent effective hamiltonian. We have conducted this study with this particular channel as it has the highest branching ratio among the various purely leptonic and semi-leptonic decay modes, making this mode particularly useful for studying physics beyond the SM. We have also analyzed the effects on these polarization asymmetries, and hence the physics underlying it, when complex phases are included in some of the Wilson coefficients.

Probing the Higgs boson via vector boson fusion with single jet tagging at the LHC

The signature produced by the Standard Model Higgs boson in the vector boson fusion (VBF) mechanism is usually pinpointed by requiring two well separated hadronic jets, one of which (at least) tends to be in the forward direction. With the increase of instantaneous luminosity at the LHC, the isolation of the Higgs boson produced with the VBF mechanism is rendered more challenging. In this paper the feasibility of single jet tagging is explored in a high-luminosity scenario. It is demonstrated that the separation in rapidity between the tagging jet and the Higgs boson can be effectively used to isolate the VBF signal. This variable is robust from the experimental and QCD standpoints. Single jet tagging allows us to probe the spin-CP quantum numbers of the Higgs boson.

Little Higgs model effects at gamma gamma collider

Though the predictions of the standard model (SM) are in excellent agreement with experiments there are still several theoretical problems, such as fine-tuning and the hierarchy problem. These problems are associated with the Higgs sector of the SM, where it is widely believed that some new physics will take over at the TeV scale. One beyond the SM theory which resolves these problems is the little Higgs model. In this work we shall investigate the effects of the little Higgs model on {gamma}{gamma}{yields}{gamma}{gamma} scattering, where the process {gamma}{gamma}{yields}{gamma}{gamma} at high energies occurs in the SM through diagrams involving W, charged quark, and lepton loops (and is, therefore, particularly sensitive to any new physics)

The impact of additional scalar bosons at the LHC

In this study we consider an effective model by introducing two hypothetical real scalars,

The Madala hypothesis with Run 1 and 2 data at the LHC

H

Exploring CP-even scalars of a Two Higgs-doublet model in future

and

e^-\,p

chi