arXiv subjects

Sven-Olaf Moch

Publications and source records attributed to Sven-Olaf Moch.

At least 73 records · Page 4Linked to original sources

arXiv2013

Phenomenology of threshold corrections for inclusive jet production at hadron colliders

We study one-jet inclusive hadro-production and compute the QCD threshold corrections for large transverse momentum of the jet in the soft-gluon resummation formalism at next-to-leading logarithmic accuracy. We use the resummed result to generate approximate QCD corrections at next-to-next-to leading order, compare with results in the literature and present rapidity integrated distributions of the jet's transverse momentum for Tevatron and LHC. For the threshold approximation we investigate its kinematical range of validity as well as its dependence on the jet's cone size and kinematics.

hep-ph↗

arXiv2013

Top-quark production at the LHC: differential cross section and phenomenological applications

We discuss top-quark pair production at hadron colliders and review available calculations of differential top-pair production cross section in perturbative QCD at approximate next-to-next-to-leading order (NNLO) within the threshold resummation formalism. These calculations are implemented into an open source program under development. We present phenomenological studies at the LHC that include transverse momentum and rapidity distribution of the top quarks at a center-of-mass energy of 7 TeV. Preliminary results obtained with this program are in very good agreement with the recent LHC measurements.

hep-ph↗

arXiv2013

Differential distributions for top-quark hadro-production with a running mass

We take a look at how the differential distributions for top-quark production are affected by changing to the running mass scheme. Specifically we consider the transverse momentum, rapidity and pair-invariant mass distributions at NLO for the top-quark mass in the MSbar scheme. It is found that, similar to the total cross section, the perturbative expansion converges faster and the scale dependence improves using the mass in the MSbar scheme as opposed to the on-shell scheme. We also update the analysis for the total cross section using the now available full NNLO contribution.

hep-ph↗

arXiv2013

A new observable to measure the top-quark mass at hadron colliders

A new method to measure the top-quark mass in high energetic hadron collisions is presented. We use theoretical predictions calculated at next-to-leading order accuracy in quantum chromodynamics to study the (normalized) differential distribution of the \ttbaronejet cross section with respect to its invariant mass $\sqrt{\sttj}$. The sensitivity of the method to the top-quark mass together with the impact of various theoretical and experimental uncertainties has been investigated and quantified. The new method allows for a complementary measurement of the top-quark mass parameter and has a high potential to become competitive in precision with respect to established approaches. Furthermore we emphasize that in the proposed method the mass parameter is uniquely defined through one-loop renormalization.

hep-ph↗

arXiv2012

QCD threshold corrections for gluino pair production at hadron colliders

We present the complete threshold enhanced predictions in QCD for the total cross section of gluino pair production at hadron colliders at next-to-next-to-leading order. Thanks to the computation of the required one-loop hard matching coefficients our results are accurate to the next-to-next-to-leading logarithm. In a brief phenomenological study we provide predictions for the total hadronic cross sections at the LHC and we discuss the uncertainties arising from scale variations and the parton distribution functions.

hep-ph↗

arXiv2012

Top-quark pair-production with one jet and parton showering at hadron colliders

We present heavy-flavor production in association with one jet in hadronic collisions matched to parton shower Monte Carlo predictions at next-to-leading order QCD with account of top-quark decays and spin correlations. We use the POWHEGBOX for the interface to the parton shower programs PYTHIA or HERWIG. Phenomenological studies for the LHC and the Tevatron are presented with particular emphasis on the inclusion of spin-correlation effects in top decay and the impact of the parton shower on the top-quark charge asymmetries. As a novel application of the present calculation the measurement of the top-quark mass is discussed.

hep-ph↗

arXiv2012

Vector boson fusion at NNLO in QCD: SM Higgs and beyond

Weak vector boson fusion provides a unique channel to directly probe the mechanism of electroweak symmetry breaking at hadron colliders. We present a method that allows to calculate total cross sections to next-to-next-to-leading order (NNLO) in QCD for an arbitrary V* V* -> X process, the so-called structure function approach. By discussing the case of Higgs production in detail, we estimate several classes of previously neglected contributions and we argue that such method is accurate at a precision level well above the typical residual scale and PDF uncertainties at NNLO. Predictions for cross sections at the Tevatron and the LHC are presented for a variety of cases: the Standard Model Higgs (including anomalous couplings), neutral and charged scalars in extended Higgs sectors and (fermiophobic) vector resonance production. Further results can be easily obtained through the public use of the VBF@NNLO code.

hep-ph↗

arXiv2012

Hadronic top-quark pair-production with one jet and parton showering

We present a calculation of heavy-flavor production in hadronic collisions in association with one jet matched to parton shower Monte Carlo programs at next-to-leading order in perturbative QCD. Top-quark decays are included and spin correlations in the decay products are taken into account. The calculation builds on existing results for the radiative corrections to heavy-quark plus one jet production and uses the POWHEG BOX for the interface to the parton shower programs PYTHIA or HERWIG. A broad phenomenological study for the Large Hadron Collider and the Tevatron is presented. In particular we study---as one important sample application---the impact of the parton shower on the top-quark charge asymmetry.

hep-ph↗

arXiv2011

The PDF4LHC Working Group Interim Report

This document is intended as a study of benchmark cross sections at the LHC (at 7 TeV) at NLO using modern parton distribution functions currently available from the 6 PDF fitting groups that have participated in this exercise. It also contains a succinct user guide to the computation of PDFs, uncertainties and correlations using available PDF sets. A companion note, also submitted to the archive, provides an interim summary of the current recommendations of the PDF4LHC working group for the use of parton distribution functions and of PDF uncertainties at the LHC, for cross section and cross section uncertainty calculations.

hep-ph↗

arXiv2010

Charged Higgs production via vector-boson fusion at NNLO in QCD

We present the total cross sections at next-to-next-to-leading order (NNLO) in the strong coupling for single and double charged Higgs production via weak boson fusion. Results are obtained via the structure function approach, which builds upon the approximate, though very accurate, factorization of the QCD corrections between the two quark lines. The theoretical uncertainty on the total cross sections at the LHC from higher order corrections and the parton distribution uncertainties are estimated at the 2% level each for a wide range of Higgs boson masses.

hep-ph↗

arXiv2010

Higgs production via vector-boson fusion at NNLO in QCD

We present the total cross sections at next-to-next-to-leading order (NNLO) in the strong coupling for Higgs production via weak boson fusion. Our results are obtained via the structure function approach, which builds upon the approximate, though very accurate, factorization of the QCD corrections between the two quark lines. The theoretical uncertainty on the total cross sections at the LHC from higher order corrections and the parton distribution uncertainties are estimated at the 2% level each for a wide range of Higgs boson masses.

hep-ph↗

arXiv2010

Higgs production at NNLO in QCD: the VBF channel

We present a phenomenological study for the production of the Higgs boson at next-to-next-to-leading order (NNLO) in QCD via the vector boson fusion (VBF) process. After a general discussion about the different production channels of the Higgs, we show results for hadron colliders like LHC and Tevatron in VBF. The theoretical predictions are obtained using the structure function approach. This approximation turns out to be more accurate than the precision to which the VBF Higgs production channel can be considered a well defined process by itself and the theoretical uncertainty are of the order of 1-2%. The uncertainties due to parton distributions are also discussed and are estimated to be at the same level.

hep-ph↗

arXiv2010

Measuring the running Top quark mass

In this contribution we discuss conceptual issues of current mass measurements performed at the Tevatron. In addition we propose an alternative method which is theoretically much cleaner and to a large extend free from the problems encountered in current measurements. In detail we discuss the direct determination of the top-quark's running mass from the cross section measurements performed at the Tevatron.

hep-ph↗

arXiv2009

Higher-order soft corrections to squark hadro-production

We present new predictions for the total cross section of squark pair-production at Tevatron and LHC through next-to-next-to-leading order within the Minimal Supersymmetric Standard Model. The results are based on the numerically dominant soft corrections. They are exact in all logarithmically enhanced terms near threshold, include the Coulomb corrections at two loops and exact scale dependence. We translate the increased total cross section at next-to-next-to-leading order into improved exclusion limits for squark masses and we investigate the scale dependence as well as the sensitivity on the parton luminosity.

hep-ph↗

arXiv2005

Analytic Continuation of the Harmonic Sums for the 3--Loop Anomalous Dimensions

We present for numerical use the analytic continuations to complex arguments of those basic Mellin transforms, which build the harmonic sums contributing to the 3--loop anomalous dimensions. Eight new basic functions contribute in addition to the analytic continuations for the 2--loop massless Wilson coefficients calculated previously. The representations derived have a relative accuracy of better than $10^{-7}$ in the range $x ε[10^{-6},0.98]$.

hep-ph↗

arXiv2003

Conventional Physics Explanations for the NuTeV sin2ThetaW

The NuTeV experiment has measured sin^2Theta_W = 0.2277 +/- 0.0013(stat) +/- 0.0009(syst), approximately 3 standard deviations above the standard model prediction. This discrepancy has motivated speculation that the NuTeV result may be affected significantly by neglected experimental or theoretical effects. We examine the case for a number of proposed explanations.

hep-ph↗

arXiv1998

Soft Gluon Resummation for Heavy Quark Electroproduction

We present the threshold resummation for the cross section for electroproduction of heavy quarks. We work to next-to-leading logarithmic accuracy, and in single-particle inclusive kinematics. We provide next-to-leading and next-to-next-to-leading order expansions of our resummed formula, and examine numerically the quality of these finite order approximations. For the case of charm we study their impact on the structure function $F_2$ and its differential distribution with respect to the charm transverse momentum.

hep-ph↗

arXiv1996

(4,4) superfield supergravity

We present the N=4 superspace constraints for the two-dimensional (2d) off-shell (4,4) supergravity with the superfield strengths expressed in terms of a (4,4) twisted (scalar) multiplet TM-I, as well as the corresponding component results, in a form suitable for applications. The constraints are shown to be invariant under the N=4 super-Weyl transformations, whose N=4 superfield parameters form another twisted (scalar) multiplet TM-II. To solve the constraints, we propose the Ansatz which makes the N=4 superconformal flatness of the N=4 supergravity curved superspace manifest. The locally (4,4) supersymmetric TM-I matter couplings, with the potential terms resulting from spontaneous supersymmetry breaking, are constructed. We also find the full (4,4) superconformally invariant (improved) TM-II matter action. The latter can be extended to the (4,4) locally supersymmetric Liouville action which is suitable for describing (4,4) supersymmetric non-critical strings.

hep-th↗