Matteo Cacciari

Large-p⊥ hadroproduction of heavy quarks

Abstract The production of heavy quarks at large p ⊥ ( p ⊥ ⪢ m ) in hadronic collisions is considered. The analysis is carried out in the framework of perturbative fragmentation functions, thereby allowing a resummation at the NLO level of final-state large-mass logarithms of the kind log( p ⊥ / m ). The case of b-quark production is considered in detail. The resulting theoretical uncertainty from renormalization/factorization scales at large p ⊥ is found to be much smaller than that shown by the full O( α s 3 ) perturbative calculation.

Charmonium production at the Tevatron

Abstract We present in this work a study of large-pT charmonium production in hadronic collisions. We work in the framework of the factorization model of Bodwin, Braaten and Lepage, thereby including the colour octet production mechanism, and extract the values of the necessary non-perturbative parameters from a comparison with the most recent data from the Fermilab 1.8 TeV p p hadron collider. We extend the calculation to 630 GeV, and compare the results with data published by the UA1 Collaboration. The global agreement is satisfactory, indicating that the largest components of the mechanisms for charmonium production at high pT have been isolated.

SABSPV: A Monte Carlo integrator for small angle Bhabha scattering

SABSPV is a code designed to perform a theoretical evaluation of small-angle Bhabha scattering cross sections by suitably matching fixed-order perturbative calculations and structure-function techniques. The implementation of realistic experimental triggering conditions is achieved by using Monte Carlo integration.SABSPV is a code designed to perform a theoretical evaluation of small-angle Bhabha scattering cross sections by suitably matching fixed-order perturbative calculations and structure-function techniques. The implementation of realistic experimental triggering conditions is achieved by using Monte Carlo integration.

QED Structure Functions: A Systematic Approach

The problem of calculating higher-order contributions to QED structure functions is considered. A closed form for any given perturbative order is developed by means of a systematic approach. Analytical formulae for the structure function and its generating function are explicitly computed at the leading log level up to O(α3). An alternative approach to the calculation of the n-th order contribution to the structure function, particularly useful for numerical applications, is developed. A numerical study of the relevance of third- and fourth-order hard-photon contribution is performed.

Bhabha scattering at LEP. Large angle

Abstract QED radiative corrections to large angle Bhabha scattering at high energy are computed in the structure function approach. A realistic description of the process is developed and accurate numerical results are derived by means of the FORTRAN code 40THIEVES. Various Bhabha scattering observables (differential and total cross sections, forward-backward asymmetry and acollinearity distributions) are computed taking into account different cuts of experimental interest. The predictions are compared with those of other programs currently used at LEP and are found to be in good agreement. The relevance of QED corrections left-over in existing calculations and here included is critically discussed in view of an actually high precision theoretical knowledge of the Bhabha cross section.

A critical analysis of radiative corrections to Bhabha scattering

Abstract The full one loop weak corrections plus QED corrections including exponentiation and up to O( α 2 sub-leading logs have been computed for both small and large angle Bhabha scattering. A critical comparison is shown with the results obtained through an improved Born approximation to the full weak corrections. The overall agreement between the two approaches is found to be fully satisfactory for several measurable quantities, including the forward-backward asymmetry and the charge asymmetry. A comparison is also shown and commented with other existing calculations.

Bhabha scattering at LEP. Small angle

Abstract The structure function approach to small angle Bhabha scattering at high energy is presented. Electroweak radiative corrections and various experimental cuts on energies, scattering angles and acollinearity are accounted for in a general formula providing a realistic cross section. Accurate numerical results obtained by the FORTRAN code 40THIEVES are compared with those of existing generators and found in good agreement. The relevance of next-to-leading second order corrections and final hard collinear photons for high precision luminosity determination at LEP is investigated.

A critical analysis of radiative corrections to e+e−→μ+μ−

Abstract The full one loop weak corrections plus QED corrections including exponentiation and up to O(α 2 ) sub-leading logs have been computed for the process e + e − →μ + μ − at LEP energies. A critical comparison is shown with the results obtained through an improved Born approximation to the full weak corrections computed by using two independent methods. The overall agreement between the exact and approximated approaches is found to be fully satisfactory for several measurable quantities, including the line shape and forward-backward asymmetry. Comparisons are also shown and commented with other existing calculations.

Collinear photons from final state leptons

Abstract The emission of hard collinear photons by final state charged leptons is investigated within the collinear approximation. A closed analytic form for the emission rate is derived without any restriction on the value of the calorimetric threshold, thus generalizing the existing results. The numerical relevance of our conclusions is shown and discussed in the case of hard collinear bremsstrahlung by final state electrons in processes of current experimental interest.

Higher order QED corrections toW pair production at LEP II

AbstractThe problem of evaluating initial state QED corrections to theW pair production cross section, taking into account the effects of finiteW width, is investigated. The contributions of higher order corrections compared with then