Carlo Michel Carloni Calame

Precision electroweak calculation of the charged current Drell-Yan process

We present a detailed study of the charged current Drell-Yan process, which includes the exact (α) electroweak corrections properly matched with leading-log effects due to multiple-photon emission, as required by the experiments at the Tevatron and the LHC. Numerical results for the relevant observables of single W boson production at hadron colliders are presented. The impact of the radiative corrections and of some sources of theoretical uncertainty is discussed in detail. The calculation has been implemented in the new version of the event generator HORACE, which is available for precision simulations of the charged current Drell-Yan process.

Matching perturbative and parton shower corrections to Bhabha process at flavour factories

We report on a high-precision calculation of the Bhabha process in Quantum Electrodynamics, of interest for precise luminosity determination of electron-positron colliders involved in R measurements in the region of hadronic resonances. The calculation is based on the matching of exact next-to-leading order corrections with a Parton Shower algorithm. The accuracy of the approach is demonstrated in comparison with existing independent calculations and through a detailed analysis of the main components of theoretical uncertainty, including two-loop corrections, hadronic vacuum polarization and light pair contributions. The calculation is implemented in an improved version of the event generator BABAYAGA with a theoretical accuracy of the order of 0.1%. The generator is now available for high-precision simulations of the Bhabha process at flavour factories.

Multiple photon corrections to the neutral-current Drell-Yan process

Precision studies of single W and Z production processes at hadron colliders require progress in the calculation of electroweak radiative corrections. To this end, higher-order QED corrections to the neutral-current Drell-Yan process, due to multiple photon radiation in Z leptonic decays, are calculated. Particular attention is paid to the effects induced by such corrections on the experimental observables which are relevant for high-precision measurements of the W-boson mass at the Tevatron Run II and the LHC. The calculation is implemented in the Monte Carlo event generator HORACE, which is available for data analysis.

An improved parton shower algorithm in QED

Abstract An improved QED Parton Shower algorithm to calculate photonic radiative corrections to QED processes at flavour factories is described. We consider the possibility of performing photon generation in order to take into account also the effects due to interference between initial and final state radiation. Comparisons with exact order α results are shown and commented.

Higgs boson decay into four leptons at NLOPS electroweak accuracy

A bstractIn view of precision studies of the Higgs sector at the Run II of the LHC, the improvement of the accuracy of the theoretical prediction is becoming a pressing issue. In this framework, we detail a calculation of the full Next-to-Leading Order (NLO) electroweak corrections to Higgs boson decay into four charged leptons, by considering the gold-plated channel H → Z(∗)Z(∗) → 2ℓ2ℓ′, ℓ, ℓ′= e, μ. We match the NLO corrections with a QED Parton Shower (PS), in order to simulate exclusive multiple photon emission and provide novel results at NLOPS electroweak accuracy. We compare our NLO predictions to those of the program Prophecy4f and present NLOPS phenomenological results relevant for Higgs physics studies, with particular attention to precision measurements of the Higgs boson mass, spin-parity assignment and tests of the Standard Model. Our calculation is implemented in a new code, Hto4l, which can be easily interfaced to any generator describing Higgs boson production. As an example, we provide illustrative results for Higgs production and decay in the process gg → H → 4ℓ using POWHEG with NLOPS accuracy in the production mode.

Precision Measurement of the W-Boson Mass: Theoretical Contributions and Uncertainties

We perform a comprehensive analysis of electroweak, QED and mixed QCD-electroweak corrections underlying the precise measurement of the W-boson mass M_W at hadron colliders. By applying a template fitting technique, we detail the impact on M_W of next-to-leading order electroweak and QCD corrections, multiple photon emission, lepton pair radiation and factorizable QCD-electroweak contributions. As a by-product, we provide an up-to-date estimate of the main theoretical uncertainties of perturbative nature. Our results can serve as a guideline for the assessment of the theoretical systematics at the Tevatron and LHC and allow a more robust precision measurement of the W-boson mass at hadron colliders.

Higgs decay into four charged leptons in the presence of dimension-six operators

A bstractWe study the indirect effects of New Physics in the Higgs decay into four charged leptons, using an Effective Field Theory (EFT) approach to Higgs interactions. We evaluate the deviations induced by the EFT dimension-six operators in observables like partial decay width and various kinematic distributions, including angular observables, and compare them with the contribution of the full SM electroweak corrections. The calculation is implemented in an improved version of the event generator Hto4l, which can provide predictions in terms of different EFT-bases and is available for data analysis at the LHC. We also perform a phenomenological study in order to assess the benefits coming from the inclusion of differential information in the future analyses of very precise data which will be collected during the high luminosity phase of the LHC.

One-loop electroweak corrections to e+e- into three-jets

We describe the impact of the full one-loop Electro-Weak terms of O(aSa3EM) entering the electron-positron into three-jet cross-section. We include both factorisable and non-factorisable virtual corrections, photon bremsstrahlung but not the real emission of W± and Z bosons. We show preliminary results and we discuss the impact of the Electro-Weak corrections on three-jet observables.

Recent advances in the combination of QCD and EW corrections to the Drell-Yan processes

Departamento de Fisica Teorica y del Cosmos, CAPFE, Universidad de Granada, E-18071Granada, SpainEmail: treccani@ugr.esThe issue of matching fixed order calculations with all order results and the recipes to combineEW and QCD corrections in the simulation of the Drell-Yan processes are reviewed.RADCOR 2009 - 9th International Symposium on Radiative Corrections (Applications of Quantum FieldTheory to Phenomenology) ,October 25 - 30 2009Ascona, Switzerland