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

Associated WH production at hadron colliders: a fully exclusive QCD calculation at NNLO

We consider QCD radiative corrections to Standard Model Higgs boson production in association with a W boson 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. Our calculation includes finite-width effects, the leptonic decay of the W boson with its spin correlations, and the decay of the Higgs boson into a bbbar pair. We present selected numerical results at the Tevatron and the LHC.Comment: 7 pages, 2 figure

Associated production of a light Higgs boson and a chargino pair in the MSSM at linear colliders

In the Minimal Supersymmetric Standard Model (MSSM), we study the light Higgs-boson radiation off a light-chargino pair in the process e+e- -> h chi^+ chi^- at linear colliders with \sqs=500 GeV. We analyze cross sections in the regions of the MSSM parameter space where the process can not proceed via on-shell production and subsequent decay of either heavier charginos or the pseudoscalar Higgs boson A. Cross sections up to a few fb's are allowed, according to present experimental limits on the Higgs-boson, chargino and sneutrino masses. We also show how a measurement of the process production rate could provide a determination of the Higgs-boson couplings to charginos.Comment: 26 pages, 9 figures; figure misplacement fixed; to appear in Eur.Phys.J.

Towards a Global Perspective of the Marine Microbiome

Marine microbes play fundamental roles in nutrient cycling and climate regulation at a planetary scale. The field of marine microbial ecology has experienced major breakthroughs following the application of high-throughput sequencing and cultureindependent methodologies that have pushed the exploration of the marine microbiome to an unprecedented scale. This chapter overviews how the advances in gene- and genome-centric approaches as well as in culturing and single cell physiological methodologies in conjunction with global oceanographic circumnavigation expeditions and long-term time series are fueling our understanding of the biogeography, temporal dynamics, functional diversity, and evolutionary processes of microbial populations. We discuss how the joint effort of all those integrative approaches will help to boost our knowledge of the marine microbiome to reach a predictive understanding of how it is going to evolve in future scenarios.Versión del edito

Standard model physics at the LHC

In this brief overview, we summarize theoretical advances and discuss selected topics of Standard Model physics at the Large Hadron Collider (LHC). In particular we show some illustrative recent results in the determination of parton densities and in the calculation of QCD radiative corrections

Precise gimballing mechanism

Prototype support mechanisms allow precise and repeatable gimballing of engines with a minimum of lost motion and backlash. It also minimizes the use of gears and reduces lubrication requirements for long time space operations of several years duration

Resummed Mass Distribution for Jets Initiated by Massive Quarks

We resum to all orders of perturbation theory the invariant mass distribution of jets initiated by massive quarks. We find that the inclusion of mass terms, in the N-moment space, results in the universal factor delta_N(Q^2;m^2), taking into account dead-cone effects in gluon emission, which multiplies the massless jet distribution function J_N(Q^2). The variable N is rescaled by the mass correction parameter r = m^2/Q^2 c l nu decay spectra or the inclusion of beauty mass effects in t --> b W decays, are briefly sketched

Threshold resummation in semi-inclusive B decays

We discuss threshold resummation in radiative and charmless semileptonic B decays. To deal with the large non perturbative effects, we introduce a model for NNLL resummed form factors based on the analytic QCD coupling. By means of this model we can reproduce with good accuracy the experimental data. Finally we briefly present an improved threshold resummed formula to deal with jets initiated by massive quarks as in the case of semileptonic charmed decays