Probing colour flow with jet vetoes

We discuss jet vetoes as a means of probing colour flow in hard-scattering processes in hadronic collisions. As an example, we describe a calculation of the dijet cross-section with a jet veto, which resums the leading logarithms of the veto scale and is matched to a fixed-order computation. We compare this prediction to the measurement performed by the ATLAS collaboration. Finally, we outline future developments in this research area.Comment: Talk given at XX International Workshop on Deep-Inelastic Scattering and Related Subjects, 26th-30th March 2012, University of Bon

Vector boson production in joint resummation

We study the transverse momentum ($Q_T$) distribution of an electro-weak vector boson produced via the Drell-Yan mechanism, in the context of joint resummation. This formalism allows for the simultaneous resummation of logarithmic contributions that are enhanced at small $Q_T$ and at partonic threshold. We extend joint resummation to next-to-next-to leading logarithmic accuracy and we present resummed and matched results for three different phenomenological setups. In particular, we study the production of a $Z$ boson at the Tevatron and at the Large Hadron Collider (LHC), as well as the production of a heavier $Z^\prime$ at the LHC. We compare our findings to standard $Q_T$ resummation, as well as to fixed-order perturbation theory. We find that joint resummation provides a moderate (but not flat) correction with respect to $Q_T$ resummation and it leads to a reduction of the scale dependence of the results. However, our study also shows some limitations of this formalism. While the use of joint resummation for $Z$ production at the Tevatron and $Z^\prime$ production at the LHC appears to be justified, our implementation suffers from a stronger dependence on power corrections for processes which are further away from threshold, such as $Z$ production at the LHC, for which we cannot claim an improvement over standard $Q_T$ resummation.Comment: 28 pages, 10 figures, published versio

ANALISIS PRODUKTIVITAS MAHASISWA INSTITUT AGAMA ISLAM (IAI) NUSANTARA BATANGHARI MELALUI PEMBELAJARAN ONLINE

This paper is motivated by the conditions of learning during the Covid-19 pandemic. The learning process must be done from home. In accordance with government policy, work from home and learn from home. The purpose of this research is to study the creativity of students in implementing online learning during the Covid-19 pandemic. The research method used is using a qualitative method with descriptive analysis. And as respondents and sources of data for this study were students of IAI Nusantara Batanghari. The results showed as many as 79.4% thought online learning was very effective, while 20.6% thought it was not yet effective. That means effectiveness can increase student productivity. This result is supported by data as much as 23% they strongly agree, 44% agree, and there are 15% of students who disagree. It shows the quality of online learning, increases student productivity, both increases productivity in soft skill development and self-development increases business efficiency in meeting daily needs

High Energy Resummation of Drell-Yan Processes

We present a computation of the inclusive Drell-Yan production cross-section in perturbative QCD to all orders in the limit of high partonic centre-of-mass energy. We compare our results to the fixed order NLO and NNLO results in MSbar scheme, and provide predictions at NNNLO and beyond. Our expressions may be used to obtain fully resummed results for the inclusive cross-section.Comment: 18 pages, 5 figures: version to be published in NP

Small x resummation of rapidity distributions: the case of Higgs production

We provide a method for the all order computation of small x contributions at the leading logarithmic level to cross-sections which are differential in rapidity. The method is based on a generalization to rapidity distributions of the high energy (or k_T) factorization theorem hitherto proven for inclusive cross-sections. We apply the method to Higgs production in gluon-gluon fusion, both with finite top mass and in the infinite mass limit: in both cases, we determine all-order resummed expressions, as well as explicit expressions for the leading small x terms up to NNLO. We use our result to construct an explicit approximate analytic expression of the finite-mass NLO rapidity distribution and an estimate of finite-mass corrections at NNLO.Comment: 53 pages, 6 figures. Several typos corrected. Final version, to be published in NP

High-energy resummation at the LHC: the case of Drell-Yan processes

We first review the general framework which enables one to resum high-energy logarithms in hadronic processes, both in the evolution of parton densities and in the coefficient functions. We then present an all-order calculation in perturbative QCD of the inclusive Drell Yan and vector boson production in hadron-hadron collisions, in the limit where centre of mass energy is much bigger than the invariant mass of the final state. Our calculation resums leading non-trivial logarithms in the ratio of these two scales. We also study the phenomenological relevance of the high-energy corrections for Drell-Yan processes at the LHC. We find that the resummation corrects the NNLO result by a few percent, for values of the invariant mass of the lepton pair below 100 GeV. Corrections to W, Z production are expected to be of the same order.Comment: 5 pages, Talk given at 10th DESY Workshop on Elementary Particle Theory: Loops and Legs 2010, Worlitz, Germany 25-30 April 201

Small-xx resummation from HELL

Small-$x$ logarithmic enhancements arising from high-energy gluon emissions affect both the evolution of collinearly-factorized parton densities and partonic coefficient functions. With the higher collider energy reached by the LHC, the prospect of a future high-energy collider, and the recent deep-inelastic scattering (DIS) results at small-$x$ from HERA, providing phenomenological tools for performing small-$x$ resummation has become of great relevance. In this paper we discuss a framework to perform small-$x$ resummation for both parton evolution and partonic coefficient functions and we describe its implementation in a computer code named High-Energy Large Logarithms (HELL). We present resummed and matched results for the DGLAP splitting functions and, as a proof of principle, for the massless structure functions in DIS.Comment: Version accepted by EPJ C. 26 pages, 7 figures. Section 2.4 largely re-written. Added estimate of theoretical uncertainty and comparison to CCS