Universality of non-leading logarithmic contributions in transverse-momentum distributions

We consider the resummation of the logarithmic contributions to the region of small transverse momenta in the distributions of high-mass systems (lepton pairs, vector bosons, Higgs particles, ....) produced in hadron collisions. We point out that the resummation formulae that are usually used to compute the distributions in perturbative QCD involve process-dependent form factors and coefficient functions. We present a new universal form of the resummed distribution, in which the dependence on the process is embodied in a single perturbative factor. The new form simplifies the calculation of non-leading logarithms at higher perturbative orders. It can also be useful to systematically implement process-independent non-perturbative effects in transverse-momentum distributions. We also comment on the dependence of these distributions on the factorization and renormalization scales.Comment: misprints corrected in Eqs. (6), (7) and (12), results unchange

Higgs production in hadron collisions: soft and virtual QCD corrections at NNLO

We consider QCD corrections to Higgs boson production through gluon-gluon fusion in hadron collisions. Using the recently evaluated two-loop amplitude for this process and the corresponding factorization formulae for soft-gluon bremsstrahlung at O(alpha_s^2), we compute the soft and virtual contributions to the NNLO cross section. We also discuss soft-gluon resummation at next-to-next-to-leading logarithmic accuracy. Numerical results for Higgs boson production at the LHC are presented.Comment: 17 pages, 4 figures included. One note and one reference adde

Direct Higgs production and jet veto at hadron colliders

We consider Higgs boson production through gluon--gluon fusion in hadron collisions, when a veto is applied on the transverse momenta of the accompanying hard jets. We compute the QCD corrections to this process at NLO and NNLO, and present numerical results at the Tevatron and the LHC.Comment: 5 pages, 4 ps figures, presented at the XXXVIIth Rencontres de Moriond, QCD and Hadronic interactions, Les Arc1800, Franc

Higgs production at hadron colliders in (almost) NNLO QCD

We compute the soft and virtual NNLO QCD corrections to Higgs production through gluon-gluon fusion at hadron colliders. We present numerical results obtained at the LHC and at the Tevatron Run II.Comment: latex, 5 pages, presented at the XXXVIth Rencontres de Moriond, QCD and Hadronic interactions, Les Arc1800, France and at the 9th International Workshop on Deep Inelastic Scattering DIS2001, Bologna, Ital

Transverse-momentum resummation and the spectrum of the Higgs boson at the LHC

We consider the transverse-momentum (q_T) distribution of generic high-mass systems (lepton pairs, vector bosons, Higgs particles, ....) produced in hadron collisions. At small q_T, we concentrate on the all-order resummation of the logarithmically-enhanced contributions in QCD perturbation theory. We elaborate on the $b$-space resummation formalism and introduce some novel features: the large logarithmic contributions are systematically exponentiated in a process-independent form and, after integration over q_T, they are constrained by perturbative unitarity to give a vanishing contribution to the total cross section. At intermediate and large q_T, resummation is consistently combined with fixed-order perturbative results, to obtain predictions with uniform theoretical accuracy over the entire range of transverse momenta. The formalism is applied to Standard Model Higgs boson production at LHC energies. We combine the most advanced perturbative information available at present for this process: resummation up to next-to-next-to-leading logarithmic accuracy and fixed-order perturbation theory up to next-to-leading order. The results show a high stability with respect to perturbative QCD uncertainties.Comment: 48 pages, 13 postscript figure

Use of pharmacological treatments by a sample of Italian patients affected by alcohol use disorders

Title: USE OF PHARMACOLOGICAL TREATMENTS BY A SAMPLE OF ITALIAN PATIENTS AFFECTED BY ALCOHOL USE DISORDERS Author name(s): R. Agabio; E.M. Diana; D. Grazzini; R. Pirastu; G.L. Gessa Institution: Department of Biochemical Sciences, Section of Neuroscience, Preclinical and Clinical Pharmacology, University of Cagliari, Italy Text Background: It has often been reported that the majority of patients affected by Alcohol Use Disorders (AUDs) do not receive any pharmacological treatment. This study was aimed at investigating the use of the medications available in Italy (disulfiram, naltrexone, acamprosate, and γ-hydroxybutyric acid) by a sample of outpatients affected by AUDs. Methods: Four trained psychologists interviewed outpatients affected by AUDs in an area of Sardinia, Italy, of approximately 550.000 adult inhabitants. Results: A total sample of 208 outpatients affected by AUDs was interviewed (~1/3 of total outpatients affected by AUDs of that area). Their main features were: 166 males (79.5%); mean age=48.6±0.6 year; duration of AUDs=15.8±0.7 years; number of drinks per drinking days=19.4±1.3; number of criteria of DSM-IV-Tr=5.8±0.1. Before the admission into specific services, 13 patients (6.2%) had already received medication for AUDs; 7 patients (3.4%) had received disulfiram and 6 patients (2.9%) γ-hydroxybutyric acid. Over the same period, 22 patients (10.6%) had already attended self-help groups and 4 patients (1.9%) had received thiamine (Vitamine B1). After the admission into specific medical settings for the treatment of AUDs, 113 patients (54.3%) received medication for AUDs: 58 patients (27.9%) received disulfiram, 65 patients (31.2%) γ-hydroxybutyric acid, 2 patients (1.0%) naltrexone, and 6 patients (2.9%) acamprosate. In the same period, 54 patients (26.0%) frequented self-help associations, and 21 patients (10.1%) received thiamine. Conclusions: The results of this study confirm that the number of patients who receive a treatment for AUDs continues to be surprisingly low. Despite the long duration and the high level of severity of the AUDs, the majority of patients affected by AUDs did not receive any treatment before their admission in specific medical settings for the treatment of AUDs (10% of patients frequented self-help groups, 6% received a medication for AUDs, and 2% thiamine). After the admission into specific medical settings, the number of patients who received a treatment increased: 26% frequented self-help associations, 54% received a specific medication, and 10% received thiamine. However, approximately half of the patients did not receive any pharmacological treatment even if they frequented medical settings for the treatment of AUDs. Additional work is needed to understand the reasons of such a scarce use of treatments. Acknowledgements: This study was supported by a grant from Regione Autonoma della Sardegna

Vector boson production at hadron colliders: a fully exclusive QCD calculation at NNLO

We consider QCD radiative corrections to the production of W and Z bosons in hadron collisions. We present a fully exclusive calculation up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. To perform this NNLO computation, we use a recently proposed version of the subtraction formalism. The calculation includes the gamma-Z interference, finite-width effects, the leptonic decay of the vector bosons and the corresponding spin correlations. Our calculation is implemented in a parton level Monte Carlo program. The program allows the user to apply arbitrary kinematical cuts on the final-state leptons and the associated jet activity, and to compute the corresponding distributions in the form of bin histograms. We show selected numerical results at the Tevatron and the LHC.Comment: 7 pages, 3 ps figure

Universality of transverse-momentum resummation and hard factors at the NNLO

We consider QCD radiative corrections to the production of colourless high-mass systems in hadron collisions. The logarithmically-enhanced contributions at small transverse momentum are treated to all perturbative orders by a universal resummation formula that depends on a single process-dependent hard factor. We show that the hard factor is directly related to the all-order virtual amplitude of the corresponding partonic process. The direct relation is universal (process independent), and it is expressed by an all-order factorization formula that we explicitly evaluate up to the next-to-next-to-leading order (NNLO) in QCD perturbation theory. Once the NNLO scattering amplitude is available, the corresponding hard factor is directly determined: it controls NNLO contributions in resummed calculations at full next-to-next-to-leading logarithmic accuracy, and it can be used in applications of the q_T subtraction formalism to perform fully-exclusive perturbative calculations up to NNLO. The universality structure of the hard factor and its explicit NNLO form are also extended to the related formalism of threshold resummation.Comment: References added. Version accepted for publication on NP

Threshold resummation at N3^3LL accuracy and soft-virtual cross sections at N3^3LO

We consider QCD radiative corrections to the production of colourless high-mass systems in hadron collisions. We show that the recent computation of the soft-virtual corrections to Higgs boson production at N$^3$LO [1] together with the universality structure of soft-gluon emission can be exploited to extract the general expression of the hard-virtual coefficient that contributes to threshold resummation at N$^3$LL accuracy. The hard-virtual coefficient is directly related to the process-dependent virtual amplitude through a universal (process-independent) factorization formula that we explicitly evaluate up to three-loop order. As an application, we present the explicit expression of the soft-virtual N$^3$LO corrections for the production of an arbitrary colourless system. In the case of the Drell-Yan process, we confirm the recent result of Ref.[2].Comment: Slightly expanded text, one reference added, version published on NP

Comparing electroweak data with a decoupling model

Present data, both from direct Higgs search and from analysis of electroweak data, are starting to become rather restrictive on the possible values for the mass of the standard model Higgs. We discuss a new physics scenario based on a model with decoupling (both in a linear and in a non linear version) showing how it allows for an excellent fit to the present values of the $\epsilon$ parameters and how it widens the allowed ranges for the Higgs mass (thought as elementary in the linear version, or as composite in the non linear one).Comment: 10 pages, 3 Figures Late