Electroweak vector boson production in joint resummation

We study the application of the joint resummation to electroweak boson production at hadron colliders. The joint resummation formalism resums both threshold and transverse momentum corrections to the transverse momentum distribution at next-to-leading logarithmic accuracy. We obtain a good description of the transverse momentum distribution of Z bosons produced at the Tevatron collider.Comment: 5 pages, 2 figures. Talk presented by A. Kulesza at the XXXVIIth Rencontres de Moriond `QCD and high energy hadronic interactions', Les Arcs, Franc

The resummed Higgs boson transverse momentum distribution at the LHC

We apply QCD resummation techniques to study the transverse momentum distribution of Higgs bosons produced via gluon-gluon fusion at the LHC. In particular we focus on the joint resummation formalism which resums both threshold and transverse momentum corrections simultaneously. A comparison of results obtained in the joint and the standard recoil resummation frameworks is presented.Comment: 9 pages, 1 figure, uses appolb.cls. Contribution to the Proceedings of XXVII International Conference of Theoretical Physics, Ustron, Poland, September 15-21, 2003. To appear in Acta Physica Polonica

Polycomb Repressive Complex 2 Targets Murine Cytomegalovirus Chromatin for Modification and Associates with Viral Replication Centers

Regulation of viral transcription by chromatin structure has emerged as a fundamental determinant in the establishment of lytic and latent herpesvirus infections. The Polycomb group (PcG) of epigenetic repressors promotes heterochromatin formation by trimethylating histone H3 on lysine-27 (H3K27me3) and regulates development, stem cell renewal and differentiation and the cell cycle. These cellular processes are tightly coupled to the molecular switch between lytic and latent herpesvirus infections. Using chromatin immunoprecipitation analysis, we observed enrichment of H3K27me3 at the major immediate-early (MIE) locus of murine cytomegalovirus (MCMV) very early following infection of permissive fibroblasts. As lytic replication progressed, we observed a loss of H3K27me3 enrichment concomitant with the appearance of H3K4me3. However, late during infection, as viral replication centers are established, we observed a significant increase in PcG protein association with chromatin. Additionally, in co-immunofluorescence assays using confocal microscopy, we detected strong enrichments for PcG protein within the viral replication compartment, suggesting an association between viral DNA synthesis machinery and PcG proteins. Together, our results suggest a novel, dynamic interaction between PcG epigenetic repressors and MCMV genomes

Same-sign W pair production as a probe of double parton scattering at the LHC

We study the production of same-sign W boson pairs at the LHC in double parton interactions. Compared with simple factorised double parton distributions (dPDFs), we show that the recently developed dPDFs, GS09, lead to non-trivial kinematic correlations between the W bosons. A numerical study of the prospects for observing this process using same-sign dilepton signatures, including same-sign WWjj, di-boson and heavy flavour backgrounds, at 14 TeV centre-of-mass energy is then performed. It is shown that a small excess of same-sign dilepton events from double parton scattering over a background dominated by single scattering WZ(gamma*) production could be observed at the LHC.Comment: 14 pages, 8 figures. Added references, slight changes in the text

Non-perturbative effects and the resummed Higgs transverse momentum distribution at the LHC

We investigate the form of the non-perturbative parameterization in both the impact parameter (b) space and transverse momentum (p_T) space resummation formalisms for the transverse momentum distribution of single massive bosons produced at hadron colliders. We propose to analyse data on Upsilon hadroproduction as a means of studying the non-perturbative contribution in processes with two gluons in the initial state. We also discuss the theoretical errors on the resummed Higgs transverse momentum distribution at the LHC arising from the non-perturbative contribution.Comment: 22 pages, 10 figure

Phenomenological studies in QCD resummation

We study applications of QCD soft-gluon resummations to electroweak annihilation cross sections. We focus on a formalism that allows to resum logarithmic corrections arising near partonic threshold and at small transverse momentum simultaneously.Comment: 7 pages, LaTeX, 3 figures as eps files. Talk presented by W. Vogelsang at the "XVI International Conference on Particles and Nuclei (PaNic02)", Osaka, Japan, September 200

The q_T spectrum of the Higgs boson at the LHC in QCD perturbation theory

We consider the transverse-momentum (q_T) distribution of Higgs bosons produced at hadron colliders. We use a formalism that uniformly treats both the small-q_T and large-q_T regions in QCD perturbation theory. At small q_T (q_T << M_H, M_H being the mass of the Higgs boson), we implement an all-order resummation of logarithmically-enhanced contributions up to next-to-next-to-leading logarithmic accuracy. At large q_T (q_T \gtap M_H), we use fixed-order perturbation theory up to next-to-leading order. The resummed and fixed-order approaches are consistently matched by avoiding double-counting in the intermediate-q_T region. In this region, the introduction of unjustified higher-order terms is avoided by imposing unitarity constraints, so that the integral of the q_T spectrum exactly reproduces the perturbative result for the total cross section up to next-to-next-to-leading order. Numerical results at the LHC are presented. These show that the main features of the q_T distribution are quite stable with respect to perturbative QCD uncertainties.Comment: 9 pages, 2 postscript figure

Threshold resummation for high-transverse-momentum Higgs production at the LHC

We study the resummation of large logarithmic QCD corrections for the process pp ->H+ X when the Higgs boson H is produced at high transverse momentum. The corrections arise near the threshold for partonic reaction and originate from soft gluon emission. We perform the all-order resummation at next-to-leading logarithmic accuracy and match the resummed result with the next-to-leading order perturbative predictions. The effect of resummation on the Higgs transverse momentum distribution at the LHC is discussed.Comment: 19 pages, 3 figure

Supersymmetric top and bottom squark production at hadron colliders

The scalar partners of top and bottom quarks are expected to be the lightest squarks in supersymmetric theories, with potentially large cross sections at hadron colliders. We present predictions for the production of top and bottom squarks at the Tevatron and the LHC, including next-to-leading order corrections in supersymmetric QCD and the resummation of soft gluon emission at next-to-leading-logarithmic accuracy. We discuss the impact of the higher-order corrections on total cross sections and transverse-momentum distributions, and provide an estimate of the theoretical uncertainty due to scale variation and the parton distribution functions.Comment: 29 pages, 6 figure

Gaugino production in proton-proton collisions at a center-of-mass energy of 8 TeV

Motivated by hints for a light Standard Model-like Higgs boson and a shift in experimental attention towards electroweak supersymmetry particle production at the CERN LHC, we update in this paper our precision predictions at next-to-leading order of perturbative QCD matched to resummation at the next-to-leading logarithmic accuracy for direct gaugino pair production in proton-proton collisions with a center-of-mass energy of 8 TeV. Tables of total cross sections are presented together with the corresponding scale and parton density uncertainties for benchmark points adopted recently by the experimental collaborations, and figures are presented for up-to-date model lines attached to them. Since the experimental analyses are currently obtained with parton showers matched to multi-parton matrix elements, we also analyze the precision of this procedure by comparing invariant-mass and transverse-momentum distributions obtained in this way to those obtained with threshold and transverse-momentum resummation.Comment: 28 pages, 7 figures, 9 tables; version to appear in JHE