T. Binoth - Edinburgh University

T. Binoth
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T. Binoth
Edinburgh University

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High Energy Physics - Phenomenology (50)
High Energy Physics - Experiment (3)
High Energy Physics - Theory (2)

Publications Authored By T. Binoth

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. Read More

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. Read More

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 $q\bar{q}\to b\bar{b}b\bar{b}$. Read More

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. Read More

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. Read More

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. Read More

The production of two b-quark 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 four b-quark observables in hadronic collisions. Read More

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. Read More

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. Read More

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 u ubar -> s sbar c cbar. We demonstrate that our method leads to representations of such amplitudes which allow for efficient phase space integration. Read More

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. Read More

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. Read More

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. Read More

We give an overview of state-of-the-art multi-loop Feynman diagram computations, and explain how we use symbolic manipulation to generate renormalized integrals that are then evaluated numerically. We explain how we automate BPHZ renormalization using "henges" and "sectors", and give a brief description of the symbolic tensor and Dirac gamma-matrix manipulation that is required. We shall compare the use of general computer algebra systems such as Maple with domain-specific languages such as FORM, highlighting in particular memory management issues. Read More

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. Read More

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. Read More

Pair production of W bosons constitutes an important background to Higgs boson and new physics searches at the Large Hadron Collider LHC. We have calculated the loop-induced gluon-fusion process gg -> W*W* -> leptons, including intermediate light and heavy quarks and allowing for arbitrary invariant masses of the W bosons. While formally of next-to-next-to-leading order, the gg -> W*W* -> leptons process is enhanced by the large gluon flux at the LHC and by experimental Higgs search cuts, and increases the next-to-leading order WW background estimate for Higgs searches by about 30%. Read More

One-loop amplitudes are to a large extent determined by their unitarity cuts in four dimensions. We show that the remaining rational terms can be obtained from the ultraviolet behaviour of the amplitude, and determine universal form factors for these rational parts by applying reduction techniques to the Feynman diagrammatic representation of the amplitude. The method is valid for massless and massive internal particles. Read More

Affiliations: 1Edinburgh U., 2Wurzburg U., 3Wurzburg U., 4Wurzburg U.

We present a calculation of the loop-induced processes gg -> HH and gg -> HHH, and investigate the observability of multi-Higgs boson production at the CERN Large Hadron Collider (LHC) in the Standard Model (SM) and beyond. While the SM cross sections are too small to allow observation at the LHC, we demonstrate that physics beyond the SM can lead to amplified, observable cross sections. Furthermore, the applicability of the heavy top quark approximation in two- and three-Higgs boson production is investigated. Read More

In this talk we describe our approach for the computation of multi-leg one-loop amplitudes and present some first results relevant for LHC phenomenology. Read More

Authors: C. Buttar, S. Dittmaier, V. Drollinger, S. Frixione, A. Nikitenko, S. Willenbrock S. Abdullin, E. Accomando, D. Acosta, A. Arbuzov, R. D. Ball, A. Ballestrero, P. Bartalini, U. Baur, A. Belhouari, S. Belov, A. Belyaev, D. Benedetti, T. Binoth, S. Bolognesi, S. Bondarenko, E. E. Boos, F. Boudjema, A. Bredenstein, V. E. Bunichev, C. Buttar, J. M. Campbell, C. Carloni Calame, S. Catani, R. Cavanaugh, M. Ciccolini, J. Collins, A. M. Cooper-Sarkar, G. Corcella, S. Cucciarelli, G. Davatz, V. DelDuca, A. Denner, J. D'Hondt, S. Dittmaier, V. Drollinger, A. Drozdetskiy, L. V. Dudko, M. Duehrssen, R. Frazier, S. Frixione, J. Fujimoto, S. Gascon-Shotkin, T. Gehrmann, A. Gehrmann-De Ridder, A. Giammanco, A. -S. Giolo-Nicollerat, E. W. N. Glover, R. M. Godbole, A. Grau, M. Grazzini, J. -Ph. Guillet, A. Gusev, R. Harlander, R. Hegde, G. Heinrich, J. Heyninck, J. Huston, T. Ishikawa, A. Kalinowski, T. Kaneko, K. Kato, N. Kauer, W. Kilgore, M. Kirsanov, A. Korytov, M. Kraemer, A. Kulesza, Y. Kurihara, S. Lehti, L. Magnea, F. Mahmoudi, E. Maina, F. Maltoni, C. Mariotti, B. Mellado, D. Mercier, G. Mitselmakher, G. Montagna, A. Moraes, M. Moretti, S. Moretti, I. Nakano, P. Nason, O. Nicrosini, A. Nikitenko, M. R. Nolten, F. Olness, Yu. Pakhotin, G. Pancheri, F. Piccinini, E. Pilon, R. Pittau, S. Pozzorini, J. Pumplin, W. Quayle, D. A. Ross, R. Sadykov, M. Sandhoff, V. I. Savrin, A. Schmidt, M. Schulze, S. Schumann, B. Scurlock, A. Sherstnev, P. Skands, G. Somogyi, J. Smith, M. Spira, Y. Srivastava, H. Stenzel, Y. Sumino, R. Tanaka, Z. Trocsanyi, S. Tsuno, A. Vicini, D. Wackeroth, M. M. Weber, C. Weiser, S. Willenbrock, S. L. Wu, M. Zanetti

This Report summarises the activities of the "SM and Higgs" working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 2-20 May, 2005. On the one hand, we performed a variety of experimental and theoretical studies on standard candles (such as W, Z, and ttbar production), treating them either as proper signals of known physics, or as backgrounds to unknown physics; we also addressed issues relevant to those non-perturbative or semi-perturbative ingredients, such as Parton Density Functions and Underlying Events, whose understanding will be crucial for a proper simulation of the actual events taking place in the detectors. On the other hand, several channels for the production of the Higgs, or involving the Higgs, have been considered in some detail. Read More

A precise understanding of LHC phenomenology requires the inclusion of one-loop corrections for multi-particle final states. In this talk we describe a semi-numerical method to compute one-loop amplitudes with many external particles and present first applications. Read More

We present a formalism for the calculation of multi-particle one-loop amplitudes, valid for an arbitrary number N of external legs, and for massive as well as massless particles. A new method for the tensor reduction is suggested which naturally isolates infrared divergences by construction. We prove that for N>4, higher dimensional integrals can be avoided. Read More

Vector-boson pair production is an important background for Higgs boson and new physics searches at the Large Hadron Collider LHC. We have calculated the loop-induced gluon-fusion process gg -> WW -> leptons, allowing for arbitrary invariant masses of the intermediate W bosons. This process contributes at O(alpha_s^2) relative to quark-antiquark annihilation, but its importance is enhanced by the large gluon flux at the LHC and by experimental cuts employed in Higgs boson searches. Read More

Authors: LHC/LC Study Group, :, G. Weiglein, T. Barklow, E. Boos, A. De Roeck, K. Desch, F. Gianotti, R. Godbole, J. F. Gunion, H. E. Haber, S. Heinemeyer, J. L. Hewett, K. Kawagoe, K. Monig, M. M. Nojiri, G. Polesello, F. Richard, S. Riemann, W. J. Stirling, A. G. Akeroyd, B. C. Allanach, D. Asner, S. Asztalos, H. Baer, M. Battaglia, U. Baur, P. Bechtle, G. Belanger, A. Belyaev, E. L. Berger, T. Binoth, G. A. Blair, S. Boogert, F. Boudjema, D. Bourilkov, W. Buchmuller, V. Bunichev, G. Cerminara, M. Chiorboli, H. Davoudiasl, S. Dawson, S. De Curtis, F. Deppisch, M. A. Diaz, M. Dittmar, A. Djouadi, D. Dominici, U. Ellwanger, J. L. Feng, I. F. Ginzburg, A. Giolo-Nicollerat, B. K. Gjelsten, S. Godfrey, D. Grellscheid, J. Gronberg, E. Gross, J. Guasch, K. Hamaguchi, T. Han, J. Hisano, W. Hollik, C. Hugonie, T. Hurth, J. Jiang, A. Juste, J. Kalinowski, W. Kilian, R. Kinnunen, S. Kraml, M. Krawczyk, A. Krokhotine, T. Krupovnickas, R. Lafaye, S. Lehti, H. E. Logan, E. Lytken, V. Martin, H. -U. Martyn, D. J. Miller, S. Moretti, F. Moortgat, G. Moortgat-Pick, M. Muhlleitner, P. Niezurawski, A. Nikitenko, L. H. Orr, P. Osland, A. F. Osorio, H. Pas, T. Plehn, W. Porod, A. Pukhov, F. Quevedo, D. Rainwater, M. Ratz, A. Redelbach, L. Reina, T. Rizzo, R. Ruckl, H. J. Schreiber, M. Schumacher, A. Sherstnev, S. Slabospitsky, J. Sola, A. Sopczak, M. Spira, M. Spiropulu, Z. Sullivan, M. Szleper, T. M. P. Tait, X. Tata, D. R. Tovey, A. Tricomi, M. Velasco, D. Wackeroth, C. E. M. Wagner, S. Weinzierl, P. Wienemann, T. Yanagida, A. F. Zarnecki, D. Zerwas, P. M. Zerwas, L. Zivkovic

Physics at the Large Hadron Collider (LHC) and the International e+e- Linear Collider (ILC) will be complementary in many respects, as has been demonstrated at previous generations of hadron and lepton colliders. This report addresses the possible interplay between the LHC and ILC in testing the Standard Model and in discovering and determining the origin of new physics. Mutual benefits for the physics programme at both machines can occur both at the level of a combined interpretation of Hadron Collider and Linear Collider data and at the level of combined analyses of the data, where results obtained at one machine can directly influence the way analyses are carried out at the other machine. Read More

We discuss algebraic/numeric methods to compute one-loop corrections for multiparticle/jet production cross sections. By using efficient reduction algorithms a compact expression for the ggg\gamma\gamma -> 0 amplitude is obtained. Further a numerical approach for 6-point 1-loop diagrams is presented. Read More

This report documents the results obtained by the Working Group on Quantum Chromodynamics and the Standard Model for the Workshop `Physics at TeV Colliders'', Les Houches, France, 26 May - 6 June 2003. After a Monte Guide description, the first contributions report on progress in describing multiple interactions, important for the LHC, and underlying events. An announcement of a Monte Carlo database, under construction, is then followed by a number of contributions improving parton shower descriptions. Read More

In a series of papers we have developed the method of iterated sector decomposition for the calculation of infrared divergent multi-loop integrals. Here we apply it to phase space integrals to calculate a contribution to the double real emission part of the e+e- -> 2 jets cross section at NNLO. The explicit cancellation of infrared poles upon summation over all possible cuts of a given topology is worked out in detail for a specific example. Read More

A compact representation of the loop amplitude gamma gamma ggg -> 0 is presented. The result has been obtained by using helicity methods and sorting with respect to an irreducible function basis. We show how to convert spinor representations into a field strength representation of the amplitude. Read More

In a recent paper we have presented an automated subtraction method for divergent multi-loop/leg integrals in dimensional regularisation which allows for their numerical evaluation, and applied it to diagrams with massless internal lines. Here we show how to extend this algorithm to Feynman diagrams with massive propagators and arbitrary propagator powers. As applications, we present numerical results for the master 2-loop 4-point topologies with massive internal lines occurring in Bhabha scattering at two loops, and for the master integrals of planar and non-planar massless double box graphs with two off-shell legs. Read More

In this article I review recent progress towards the analytical calculation of massless 6--point amplitudes. A way to organize such calculations is sketched and results for scattering amplitudes in the Yukawa model are presented. Read More

We derive an analytic expression for the scalar one-loop pentagon and hexagon functions which is convenient for subsequent numerical integration. These functions are of relevance in the computation of next-to-leading order radiative corrections to multi-particle cross sections. The hexagon integral is represented in terms of n-dimensional triangle functions and (n+2)-dimensional box functions. Read More

This Report documents the results obtained by the Working Group on Quantum ChromoDynamics and the Standard Model for the Workshop ``Physics at TeV Colliders'', Les Houches, France, 21 May - 1 June 2001. The account of uncertainties in Parton Distribution Functions is reviewed. Progresses in the description of multiparton final states at Next-to-Leading Order and the extension of calculations for precision QCD observables beyond this order are summarized. Read More

We discuss the production of photon-pion and pion pairs with a large invariant mass at collider energies. We present a study based on a perturbative QCD calculation at full next-to-leading order accuracy, implemented in the computer programme DIPHOX. We give estimations for various observables, which concern the reducible background to the Higgs boson search in the channel H --> gamma gamma, in the mass range 80-140 GeV at the LHC. Read More

We use an n-dimensional projection method to calculate helicity amplitudes for photon-photon scattering up to the two-loop level, for massless particles inside the loop. We confirm the recent standard model results found by Bern et al using another calculational method. We further apply the method to N=1 and N=2 supersymmetric QED. Read More

We discuss the production of pion pairs with a large invariant mass in hadronic collisions. We present a study based on a perturbative QCD calculation at full next-to-leading order accuracy, implemented in the computer programme DIPHOX. We provide a comparison of various predictions with the corresponding observables measured by the E706 fixed target experiment. Read More

Authors: R. -D. Heuer, D. J. Miller, F. Richard, P. M. Zerwas, J. A. Aguilar-Saavedra, J. Alcaraz, A. Ali, S. Ambrosanio, A. Andreazza, J. Andruszkow, B. Badelek, A. Ballestrero, T. Barklow, A. Bartl, M. Battaglia, T. Behnke, G. Belanger, D. Benson, M. Berggren, W. Bernreuther, M. Besancon, J. Biebel, O. Biebel, I. Bigi, J. J. van der Bij, T. Binoth, G. A. Blair, C. Blochinger, J. Blumlein, M. Boonekamp, E. Boos, G. Borissov, A. Brandenburg, J. -C. Brient, G. Bruni, K. Busser, P. Burrows, R. Casalbuoni, C. Castanier, P. Chankowski, A. Chekanov, R. Chierici, S. Y. Choi, P. Christova, P. Ciafaloni, D. Comelli, G. Conteras, M. Danilov, W. Da Silva, A. Deandrea, W. de Boer, S. De Curtis, S. J. De Jong, A. Denner, A. De Roeck, K. Desch, E. De Wolf, S. Dittmaier, V. Djordjadze, A. Djouadi, D. Dominici, M. Doncheski, M. T. Dova, V. Drollinger, H. Eberl, J. Erler, A. Eskreys, J. R. Espinosa, N. Evanson, E. Fernandez, J. Forshaw, H. Fraas, F. Franke, A. Freitas, F. Gangemi, P. Garcia-Abia, R. Gatto, P. Gay, T. Gehrmann, A. Gehrmann-De Ridder, U. Gensch, N. Ghodbane, I. F. Ginzburg, R. Godbole, S. Godfrey, G. Gounaris, M. Grazzini, E. Gross, B. Grzadkowski, J. Guasch, J. F. Gunion, K. Hagiwara, T. Han, K. Harder, R. Harlander, R. Hawkings, S. Heinemeyer, S. Hesselbach, C. A. Heusch, J. Hewett, G. Hiller, A. Hoang, W. Hollik, J. I. Illana, V. A. Ilyin, D. Indumathi, S. Ishihara, M. Jack, S. Jadach, F. Jegerlehner, M. Jezabek, G. Jikia, L. Jonsson, P. Jankowski, P. Jurkiewicz, A. Juste, A. Kagan, J. Kalinowski, M. Kalmykov, P. Kalyniak, B. Kamal, J. Kamoshita, S. Kanemura, F. Kapusta, S. Katsanevas, R. Keranen, V. Khoze, A. Kiiskinen, W. Kilian, M. Klasen, J. L. Kneur, B. A. Kniehl, M. Kobel, K. Kolodziej, M. Kramer, S. Kraml, M. Krawczyk, J. H. Kuhn, J. Kwiecinski, P. Laurelli, A. Leike, J. Letts, W. Lohmann, S. Lola, P. Lutz, P. Mattig, W. Majerotto, T. Mannel, M. Martinez, H. -U. Martyn, T. Mayer, B. Mele, M. Melles, W. Menges, G. Merino, N. Meyer, D. J. Miller, P. Minkowski, R. Miquel, K. Monig, G. Montagna, G. Moortgat-Pick, P. Mora de Freitas, G. Moreau, M. Moretti, S. Moretti, L. Motyka, G. Moultaka, M. Muhlleitner, U. Nauenberg, R. Nisius, H. Nowak, T. Ohl, R. Orava, J. Orloff, P. Osland, G. Pancheri, A. A. Pankov, C. Papadopoulos, N. Paver, D. Peralta, H. T. Phillips, F. Picinini, W. Placzek, M. Pohl, W. Porod, A. Pukhov, A. Raspereza, D. Reid, S. Riemann, T. Riemann, S. Rosati, M. Roth, S. Roth, C. Royon, R. Ruckl, E. Ruiz-Morales, M. Sachwitz, J. Schieck, H. -J. Schreiber, D. Schulte, M. Schumacher, R. D. Settles, M. Seymour, R. Shanidze, T. Sjostrand, M. Skrzypek, S. Soldner-Rembold, A. Sopczak, H. Spiesberger, M. Spira, H. Steiner, M. Stratmann, Y. Sumino, S. Tapprogge, V. Telnov, T. Teubner, A. Tonazzo, C. Troncon, O. Veretin, C. Verzegnassi, A. Vest, A. Vicini, H. Videau, W. Vogelsang, A. Vogt, H. Vogt, D. Wackeroth, A. Wagner, S. Wallon, G. Weiglein, S. Weinzierl, T. Wengler, N. Wermes, A. Werthenbach, G. Wilson, M. Winter, A. F. Zarnecki, B. Ziaja, J. Zochowski

The TESLA Technical Design Report Part III: Physics at an e+e- Linear Collider Read More

We calculate a class of one-loop six-point amplitudes in the Yukawa model. The construction of multi-particle amplitudes is done in the string inspired formalism and compared to the Feynman diagrammatic approach. We show that there exists a surprisingly efficient way of calculating such amplitudes by using cyclic identities of kinematic coefficients and discuss in detail cancellation mechanisms of spurious terms. Read More

The precise knowledge of photon pair production rates at the LHC is crucial to estimate the sensitivity to a Higgs boson in the intermediate mass range. This background consists not only of prompt photons but also of fake photons stemming from pion decay. We present next to leading order predictions for the invariant mass distributions of pion photon and pion pairs. Read More

Affiliations: 1LAPTH, Annecy, 2LAPTH, Annecy, 3LAPTH, Annecy, 4LAPTH, Annecy

We discuss effects induced by beyond leading order contributions to photon pair production. We point out that next to leading order contributions to the fragmentation component of the signal lead to a change in the shape of distributions. This is already mildly visible in present Tevatron data though stringent isolation criteria tend to suppress the fragmentation component considerably. Read More

In order to calculate cross sections with a large number of particles/jets in the final state at next-to-leading order, one has to reduce the occurring scalar and tensor one-loop integrals to a small set of known integrals. In massless theories, this reduction procedure is complicated by the presence of infrared divergences. Working in n=4-2*epsilon dimensions, it will be outlined how to achieve such a reduction for diagrams with an arbitrary number of external legs. Read More

Within the non-perturbative 1/N expansion, we discuss numerical methods for calculating multi-loop Feynman graph needed to derive physical scattering amplitudes. We apply higher order 1/N methods to the scalar sector of the standard model, and show the existence of a mass saturation effect. The mass saturation has direct implications for future searches at the LHC and at possible muon colliders. Read More

The search for an intermediate mass Higgs boson at the LHC needs the quantitative understanding of the two-photon background. A calculation of two-photon production in hadronic collisions at full next-to-leading order is described. It includes photons originating from the hadronization of QCD partons which play an important role at the LHC. Read More

The Les Houches Workshop on Physics at TeV Colliders took place from June 8-18, 1999. One of the three working groups at Les Houches concentrated on QCD issues, both at the Tevatron Collider and at the LHC. Besides the interest in QCD in its own right, QCD dynamics plays an important role in the production mechanisms for any new physics process that might be observed at either collider, as well as any processes that may form backgrounds to the new physics. Read More

We describe a constructive procedure to separate overlapping infrared divergences in multi-loop integrals. Working with a parametric representation in D=4-2*epsilon dimensions, adequate subtractions lead to a Laurent series in epsilon, where the coefficients of the pole- and finite terms are sums of regular parameter integrals which can be evaluated numerically. We fully automatized this algorithm by implementing it into algebraic manipulation programs and applied it to calculate numerically some nontrivial 2-loop 4-point and 3-loop 3-point Feynman diagrams. Read More

A muon collider operating in the TeV energy range can be an ideal s-channel Higgs boson factory. This is especially true for a heavy Higgs boson. The non-perturbative dynamical aspects of such a Higgs boson were recently investigated with large N expansion methods at next to leading order, and reveal the existence of a mass saturation effect. Read More

We consider one-loop scalar and tensor integrals with an arbitrary number of external legs relevant for multi-parton processes in massless theories. We present a procedure to reduce N-point scalar functions with generic 4-dimensional external momenta to box integrals in (4-2\epsilon) dimensions. We derive a formula valid for arbitrary N and give an explicit expression for N=6. Read More