T. Binoth

The University of Edinburgh, Edinburgh, Scotland, United Kingdom

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Publications (79)142.81 Total impact

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    ABSTRACT: After years of waiting, and after six Les Houches workshops, the era of LHC running is finally upon us, albeit at a lower initial center-of-mass energy than originally planned. Thus, there has been a great sense of anticipation from both the experimental and theoretical communities. The last two years, in particular, have seen great productivity in the area of multi-parton calculations at leading order (LO), next-to-leading order (NLO) and next-to-next-to-leading order (NNLO), and this productivity is reflected in the proceedings of the NLM group. Both religions, Feynmanians and Unitarians, as well as agnostic experimenters, were well-represented in both the discussions at Les Houches, and in the contributions to the write-up. Next-to-leading order (NLO) is the first order at which the normalization, and in some cases the shape, of perturbative cross sections can be considered reliable. This can be especially true when probing extreme kinematic regions, as for example with boosted Higgs searches considered in several of the contributions to this writeup. A full understanding for both standard model and beyond the standard model physics at the LHC requires the development of fast, reliable programs for the calculation of multi-parton final states at NLO. There have been many advances in the development of NLO techniques, standardization and automation for such processes and this is reflected in the contributions to the first section of this writeup. Many calculations have previously been performed with the aid of semi-numerical techniques. Such techniques, although retaining the desired accuracy, lead to codes which are slow to run. Advances in the calculation of compact analytic expressions for Higgs + 2 jets have resulted in the development of much faster codes, which extend the phenomenology that can be conducted, as well as making the code available to the public for the first time. A prioritized list of NLO cross sections was assembled at Les Houches in 2005 and added to in 2007. This list includes cross sections which are experimentally important, and which are theoretically feasible (if difficult) to calculate. Basically all 2-3 cross sections of interest have been calculated, with the frontier now extending to 2 {yields} 4 calculations. Often these calculations exist only as private codes. Since 2007, two additional calculations have been completed: t{bar t}b{bar b} and W+3 jets, reflecting the advance of the NLO technology to 2 {yields} 4 processes. In addition, the cross section for b{bar b}b{bar b} has been calculated for the q{bar q} initial state with the gg initial state calculation in progress. Final states of such complexity usually lead to multi-scale problems, and the correct choice of scales to use can be problematic not only at LO, but also at NLO. The size of the higher order corrections and of the residual scale dependence at NLOcan depend strongly on whether the considered cross section is inclusive, or whether a jet veto cut has been applied. Depending on the process, dramatically different behavior can be observed upon the application of a jet veto. There is a trade-off between suppressing the NLO cross section and increasing the perturbative uncertainty, with application of a jet veto sometimes destroying the cancellation between infra-red logs of real and virtual origin, and sometimes just suppressing large (and very scale-sensitive) tree-level contributions. So far, there is no general rule predicting the type of behavior to be expected, but this is an important matter for further investigation. From the experimental side, an addition to the above wish-list that will be crucial is the determination of the accuracy to which each of the calculations needs to be known. This is clearly related to the experimental accuracy at which the cross sections can be measured at the LHC, and can determine, for example, for what processes it may be necessary to calculate electo-weak corrections, in addition to the higher order QCD corrections. On the theoretical side, it would also be interesting to categorize the impact of a jet veto on the size and stability of each of the NLO cross sections. The technology does exist to carry out a calculation for W/Z production at NNLO (QCD) and at NLO (EW). This process was placed on the wish-list in 2007 and it is unfortunate that the combined calculation has not yet been carried out, as this precision benchmark will be very useful and important at the LHC.
    04/2012
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    ABSTRACT: The production of one hard jet in association with missing transverse energy is a major LHC search channel motivated by many scenarios for physics beyond the Standard Model. In scenarios with a weakly interacting dark matter candidate, like supersymmetry, it arises from the associated production of a quark partner with the dark matter agent. We present the next-to-leading order cross section calculation as the first application of the fully automized MadGolem package. We find moderate corrections to the production rate with a strongly reduced theory uncertainty.
    Physical Review D 08/2011; · 4.69 Impact Factor
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    ABSTRACT: This report summarizes the activities of the SM and NLO Multileg Working Group of the Workshop "Physics at TeV Colliders", Les Houches, France 8-26 June, 2009.
    03/2010;
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    ABSTRACT: In this talk we review the GOLEM approach to one-loop calculations and present an automated implementation of this technique. This method is based on Feynman diagrams and an advanced reduction of one-loop tensor integrals which avoids numerical instabilities. We have extended our one-loop integral library golem95 with an automated one-loop matrix element generator to compute the virtual corrections of the process $q\bar{q}\to b\bar{b}b\bar{b}$. The implementation of the virtual matrix element has been interfaced with tree-level Monte Carlo programs to provide the full result for the above process. Comment: 8 pages, 1 figure, contribution to the proceedings of the 9th International Symposium on Radiative Corrections (RADCOR 2009), October 25-30 2009, Ascona, Switzerland
    01/2010;
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    ABSTRACT: In this talk we discuss recent progress concerning precise predictions for hadron colliders. We show results of two applications of tensor reduction using GOLEM methods: the next-to-leading order (NLO) corrections to $pp \to ZZ+$jet as an important background for Higgs particle and new physics searches at hadron colliders, and the NLO corrections to graviton plus jet hadro-production, which is an important channel for graviton searches at the Tevatron and the LHC.
    01/2010;
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    ABSTRACT: Many highly developed Monte Carlo tools for the evaluation of cross sections based on tree matrix elements exist and are used by experimental collaborations in high energy physics. As the evaluation of one-loop matrix elements has recently been undergoing enormous progress, the combination of one-loop matrix elements with existing Monte Carlo tools is on the horizon. This would lead to phenomenological predictions at the next-to-leading order level. This note summarises the discussion of the next-to-leading order multi-leg (NLM) working group on this issue which has been taking place during the workshop on Physics at TeV Colliders at Les Houches, France, in June 2009. The result is a proposal for a standard interface between Monte Carlo tools and one-loop matrix element programs.Dedicated to the memory of, and in tribute to, Thomas Binoth, who led the effort to develop this proposal for Les Houches 2009. Thomas led the discussions, set up the subgroups, collected the contributions, and wrote and edited this paper. He made a promise that the paper would be on the arXiv the first week of January, and we are faithfully fulfilling his promise. In his honour, we would like to call this the Binoth Les Houches Accord.
    Computer Physics Communications 01/2010; · 2.41 Impact Factor
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    ABSTRACT: The production of two pairs is a prominent background for Higgs and New Physics searches in various extensions of the Standard Model. We present here the next-to-leading order QCD corrections to the quark induced subprocess using the GOLEM approach for the virtual corrections. We show that our result considerably improves the prediction and conclude that the inclusion of next-to-leading order effects is indispensable for reliable studies of observables in hadronic collisions.
    Physics Letters B 01/2010; · 4.57 Impact Factor
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    ABSTRACT: A fully differential calculation of the next-to-leading order QCD corrections to the production of Z-boson pairs in association with a hard jet at the Tevatron and LHC is presented. This process is an important background for Higgs particle and new physics searches at hadron colliders. We find sizable corrections for cross sections and differential distributions, particularly at the LHC. Residual scale uncertainties are typically at the 10% level and can be further reduced by applying a veto against the emission of a second hard jet. Our results confirm that NLO corrections do not simply rescale LO predictions.
    Physics Letters B 01/2010; · 4.57 Impact Factor
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    Thomas Binoth
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    ABSTRACT: In this talk I report on recent developments and results relevant for LHC phenomenology at next-to-leading order QCD. Feynman diagrammatic and unitarity based methods have both seen considerable improvements and new ideas recently. Current approaches point towards automated evaluation of one-loop multi-particle amplitudes. Many results for notoriously difficult processes are under construction by several groups and, given the enormous recent progress, it can be concluded that LHC phenomenology at full next-to-leading order level will become the standard approximation soon. Comment: 25 pages latex, 20 eps figures included. To appear in the proceedings of the 12th International Workshop on Advanced Computing and Analysis Techniques in Physics Research, ACAT 2008, Erice, Sicily, November 3-7, 2008. Replaced with revised version, minor changes, references added
    03/2009;
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    ABSTRACT: We present a program for the numerical evaluation of form factors entering the calculation of one-loop amplitudes with up to six external legs. The program is written in Fortran95 and performs the reduction to a certain set of basis integrals numerically, using a formalism where inverse Gram determinants can be avoided. It can be used to calculate one-loop amplitudes with massless internal particles in a fast and numerically stable way.Program summaryProgram title: golem95_v1.0Catalogue identifier: AEEO_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEO_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 50 105No. of bytes in distributed program, including test data, etc.: 241 657Distribution format: tar.gzProgramming language: Fortran95Computer: Any computer with a Fortran95 compilerOperating system: Linux, UnixRAM: RAM used per form factor is insignificant, even for a rank six six-point form factorClassification: 4.4, 11.1External routines: Perl programming language (http://www.perl.com/)Nature of problem: Evaluation of one-loop multi-leg tensor integrals occurring in the calculation of next-to-leading order corrections to scattering amplitudes in elementary particle physics.Solution method: Tensor integrals are represented in terms of form factors and a set of basic building blocks (“basis integrals”). The reduction to the basis integrals is performed numerically, thus avoiding the generation of large algebraic expressions.Restrictions: The current version contains basis integrals for massless internal particles only. Basis integrals for massive internal particles will be included in a future version.Running time: Depends on the nature of the problem. A rank 6 six-point form factor at a randomly chosen kinematic point takes 0.13 seconds on an Intel Core 2 Q9450 2.66 GHz processor, without any optimisation. With compiler optimisation flag -O3 the same point takes 0.09 seconds. Timings for lower point form factors are: All form factors for five-point functions from rank 0 to rank 4: 0.04 s. All form factors for rank 5 five-point functions: 0.05 s. All form factors for four-point functions from rank 0 to rank 4: 0.01 s.
    Computer Physics Communications 01/2009; · 2.41 Impact Factor
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    T. Binoth, N. Kauer, P. Mertsch
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    ABSTRACT: A calculation of the loop-induced gluon-fusion process gg --> Z(photon)Z(photon) --> l anti-l l' anti-l' is presented, which provides an important background for Higgs boson searches in the H --> ZZ channel at the LHC. We find that the photon contribution is important for Higgs masses below the Z-pair threshold and that the gg-induced process yields a correction of about 15% relative to the NLO QCD prediction for the q anti-q-induced process when only a M(l anti-l), M(l' anti-l') > 5 GeV cut is applied.
    07/2008;
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    ABSTRACT: In this talk we present recent next-to-leading order results relevant for LHC phenomenology obtained with the GOLEM method. After reviewing the status of this Feynman diagrammatic approach for multi-leg one-loop calculations we discuss three applications: the loop-induced process gg→Z∗Z∗ and the virtual corrections to the five and six point processes qq→ZZg and . We demonstrate that our method leads to representations of such amplitudes which allow for efficient phase space integration. In this context we propose a reweighting technique of the leading order unweighted events by local K-factors.
    Nuclear Physics B - Proceedings Supplements 07/2008; · 0.88 Impact Factor
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    ABSTRACT: We present a calculation of the NLO QCD corrections for the production of three vector bosons at the LHC, namely Z Z Z, W+ W- Z, W+ Z Z, and W+ W- W+ production. The virtual corrections are computed using the recently proposed method of reduction at the integrand level (OPP reduction). Concerning the contributions coming from real emission we used the dipole subtraction to treat the soft and collinear divergences. We find that the QCD corrections for these electroweak processes are in the range between 70 and 100 percent. As such they have to be considered in experimental studies of triple vector boson production at the LHC.
    Journal of High Energy Physics 05/2008; · 5.62 Impact Factor
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    ABSTRACT: This report summarizes the activities of the NLM working group of the Workshop "Physics at TeV Colliders", Les Houches, France, 11-29 June, 2007.
    04/2008;
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    ABSTRACT: Report of the Working Group on Higgs Bosons for the Workshop, ``Physics at TeV Colliders'', Les Houches, France, 11-29 June, 2007.
    03/2008;
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    ABSTRACT: In this talk we discuss recent progress concerning precise predictions for the LHC. We give a status report of three applications of our method to deal with multi-leg one-loop amplitudes: The interference term of Higgs production by gluon- and weak boson fusion to order O(alpha^2 alpha_s^3) and the next-to-leading order corrections to the two processes pp -> ZZ jet and u ubar -> d dbar s sbar. The latter is a subprocess of the four jet cross section at the LHC.
    02/2008;
  • Nikolas Kauer, Thomas Binoth, Philipp Mertsch
    Proceedings of the XVI International Workshop on Deep-Inelastic Scattering and Related Topics; 01/2008
  • 01/2008;
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    ABSTRACT: We calculate the order O(alpha^2 alpha_s^3) interference effect between the gluon fusion and weak boson fusion processes allowed at the one-loop level in Higgs boson plus 2 jet production at the LHC. The corresponding one-loop amplitudes, which have not been considered in the literature so far, are evaluated analytically using dimensional regularisation and the necessary master integrals with massive propagators are reported. It is discussed in detail how various mechanisms conspire to make this contribution numerically negligible for experimental studies at the LHC.
    Journal of High Energy Physics 10/2007; · 5.62 Impact Factor
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    ABSTRACT: We present analytical results for all six-photon helicity amplitudes. For the computation of this loop induced process two recently developed methods, based on form factor decomposition and on multiple cuts, have been used. We obtain compact results, demonstrating the applicability of both methods to one-loop amplitudes relevant to precision collider phenomenology.
    Physics Letters B 01/2007; · 4.57 Impact Factor

Publication Stats

2k Citations
142.81 Total Impact Points

Institutions

  • 2001–2011
    • The University of Edinburgh
      • School of Physics and Astronomy
      Edinburgh, Scotland, United Kingdom
  • 2003–2009
    • Durham University
      • Department of Physics
      Durham, ENG, United Kingdom
  • 2007
    • University of Zurich
      • Institut für Theoretische Physik
      Zürich, ZH, Switzerland
  • 2006
    • Paul Scherrer Institut
      Aargau, Switzerland
  • 2004–2006
    • University of Wuerzburg
      Würzburg, Bavaria, Germany
  • 1999
    • University of Guelph
      Guelph, Ontario, Canada
    • CERN
      Genève, Geneva, Switzerland
  • 1998
    • University of Michigan
      Ann Arbor, Michigan, United States
  • 1996–1997
    • University of Freiburg
      Freiburg, Baden-Württemberg, Germany