Prakash Mathews

A framework for Higgs characterisation

A bstractWe introduce a framework, based on an effective field theory approach, that allows one to perform characterisation studies of the boson recently discovered at the LHC, for all the relevant channels and in a consistent, systematic and accurate way. The production and decay of such a boson with various spin and parity assignments can be simulated by means of multi-parton, tree-level matrix elements and of next-to-leading order QCD calculations, both matched with parton showers. Several sample applications are presented which show, in particular, that beyond-leading-order effects in QCD have nontrivial phenomenological implications.

Diphoton signals in theories with large extra dimensions to NLO QCD at hadron colliders

We present a full next-to-leading order (NLO) QCD corrections to diphoton production at the hadron colliders in both standard model and ADD model. The invariant mass and rapidity distributions of the diphotons are obtained using a semi-analytical two cut-off phase space slicing method which allows for a successful numerical implementation of various kinematical cuts used in the experiments. The fragmentation photons are systematically removed using smooth-cone-isolation cuts on the photons. The NLO QCD corrections not only stabilise the perturbative predictions but also enhance the production cross section significantly.

Unparticle physics at hadron collider via dilepton production

The scale invariant unparticle physics recently proposed by Georgi could manifest at low energies as non-integral number dU of invisible particles. Unparticles if existing, could couple to the Standard Model fields and consequently affect the collider phenomenology. We consider the DY process to explore effects of the peculiar propagator of the scalar and tensor unparticle operators. To probe these effects at hadron collider one needs to go beyond LO in QCD and hence the quantitative impact of QCD corrections for unparticle physics at LHC is investigated. We present the K-factors at LHC. Inclusion of QCD corrections to NLO stabilises the cross section with respect to scale variations.

Angular distribution of Drell–Yan process at hadron colliders to NLO-QCD in models of TeV scale gravity

In TeV scale gravity models, for dilepton production at hadron colliders, we present the NLO-QCD corrections for the double differential cross section in the invariant mass and scattering angle. For both ADD and RS models, the quantitative impact of QCD corrections for extra dimension searches at LHC and Tevatron are investigated. We present the K-factors for both ADD and RS models at LHC and Tevatron. Inclusion of QCD corrections to NLO stabilises the cross section with respect to scale variations.

NLO-QCD corrections to dilepton production in the Randall-Sundrum model

The dilepton production process at hadron colliders in the Randall-Sundrum (RS) model is studied at next-to-leading order in QCD. The NLO-QCD corrections have been computed for the virtual graviton exchange process in the RS model, in addition to the usual γ, Z-mediated processes of standard Drell-Yan. K-factors for the cross-sections at the LHC and Tevatron for differential in the invariant mass, Q, and the rapidity, Y, of the lepton pair are presented. We find the K-factors are large over substantial regions of the phase space.

PDF and scale uncertainties of various DY distributions in ADD and RS models at hadron colliders

In the extra dimension models of ADD and RS we study the dependence of the various parton distribution functions on observables of Drell–Yan processes to NLO in QCD at LHC and Tevatron energies. Uncertainties at LHC due to factorisation scales in going from leading to next-to-leading order in QCD for the various distributions get reduced by about 2.75 times for a μF range 0.5Q<μF<1.5Q. Further uncertainties arising from the error on the experimental data are estimated using the MRST parton distribution functions.

NLO-QCD corrections to e + e - → hadrons in models of TeV-scale gravity

We present results on NLO-QCD corrections to the process e+e−→ hadrons via photon-, Z- and graviton-exchange in the context of TeV-scale gravity models. The quantitative impact of these QCD corrections for searches of extra dimensions at a Linear Collider is briefly discussed.

Compton scattering in noncommutative space-time at the Next Linear Collider

We study the Compton scattering in the noncommutative counter part of QED (NC QED). Interactions in NC QED have momentum dependent phase factors and the gauge fields have Yang-Mills type couplings, this modifies the cross sections and are different from the commuting Standard Model. Collider signals of noncommutative space-time are studied at the Next Linear Collider (NLC) operating in the e mode. Results for different polarised cases are presented and it is shown that the Compton process can probe the noncommutative scale in the range of 1 - 2.5 TeV for typical proposed NLC energies.

Diphoton production in the ADD model to NLO + parton shower accuracy at the LHC

A bstractIn this paper, we present the next-to-leading order predictions for diphoton production in the ADD model, matched to the HERWIG parton shower using the MC@NLO formalism. A selection of the results is presented for d = 2–6 extra dimensions, using generic cuts as well as analysis cuts mimicking the search strategies as pursued by the ATLAS and CMS experiments.

Drell–Yan, \(ZZ\), \(W^+W^-\) production in SM & ADD model to NLO\(+\)PS accuracy at the LHC

In this paper, we present the next-to-leading order QCD corrections for di-lepton, di-electroweak boson (