LoopFest XI

US/Eastern
157 Benedum Hall (U. Pittsburgh)

157 Benedum Hall

U. Pittsburgh

(<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
Ayres Freitas (University of Pittsburgh)
Description
LoopFest XI will be held at the University of Pittsburgh, sponsored jointly by the Pittsburgh Particle physics, Astrophysics and Cosmolgy Center (Pitt-PACC) and by the Physics Department of Carnegie-Mellon University.

Note: Workshop registration will close on April 29
    • 08:20 08:30
      Welcome 10m 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      Speaker: Sally Dawson (BNL)
    • 08:30 10:00
      Morning 1 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
      Convener: Tao Han
      • 08:30
        Atlas EW/Higgs 30m
        Speaker: Marc-Andre Pleier
        Slides
      • 09:00
        CTEQ parton distributions: NNLO, heavy quarks, and LHC data 30m
        Speaker: Pavel Nadolsky
        Slides
      • 09:30
        The Les Houches NNLO wishlist/extending NLO predictions 30m
        The Les Houches NLO wishlist is a compilation of NLO calculations that are both needed by the experimental community and practical from the theoretical perspective. The wish list was started in 2005, and added to in 2007 and 2009. In 2011, given the advances in automatic NLO calculations, we have closed the wish list, and instead have added a similar list for calculations needed at NNLO. I will discuss this NNLO list and why the calculations are crucial. I will also discuss multi-partonic NLO calculations such as those from Blackhat+Sherpa, show comparisons to data from ATLAS, and indicate kinematic regions/variables where the pure NLO prediction does not agree with the data, but the NLO prediction, augmented by additional NLO information from higher partonic multiplicities, does provide a better agreement. I will discuss the technical problems with such an approach and how they may be overcome.
        Speaker: Prof. Joey Huston (Michigan State University (US))
        Slides
    • 10:00 10:20
      Coffee break 20m 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)

      Eat Drink Be Merry

    • 10:20 12:20
      Morning 2 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
      Convener: Prof. Frank Petriello (University of Wisconsin-Madison)
      • 10:20
        The 4-dimensional helicity scheme beyond one-loop 30m
        Speaker: William Kilgore (Brookhaven National Lab)
        Slides
      • 10:50
        NNLO and N3LO DIS structure functions in ACOT scheme 30m
        We analyze the properties of the ACOT scheme for heavy quark production and make use of the higher-order massless results at NNLO and N3LO for the structure functions F2 and FL in neutral current deep-inelastic scattering to estimate the higher order corrections. For this purpose we decouple the heavy quark mass entering the phase space from the one entering the dynamics of the short distance cross section. We show numerically that the phase space mass is generally more important. Therefore, the dominant heavy quark mass effects at higher orders can be taken into account using the massless Wilson coefficients together with an appropriate slow-rescaling prescription implementing the phase space constraints. Combining the exact ACOT scheme at NLO with these expressions provides a very good approximation to the missing full calculation in the ACOT scheme at NNLO and N3LO.
        Speaker: Dr Aleksander Kusina (Southern Methodist University)
        Slides
      • 11:20
        The Charge of a Jet 30m
        I will discuss how the charge of a jet can be calculated and discuss some of its potentially interesting LHC applications, such as separating a W' from a Z'. I will give a field-theoretic description of the jet charge and establish its relationship with fragmentation functions. A comparison with Pythia will be presented.
        Speaker: Wouter Waalewijn (UCSD)
        Slides
      • 11:50
        QCD corrections in VBFNLO 30m
        Speaker: Dieter Zeppenfeld (Department of Physics)
        Slides
    • 12:20 14:00
      Lunch 1h 40m on your own

      on your own

    • 14:00 16:00
      Afternoon 1 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
      Convener: Prof. Adam Leibovich (University of Pittsburgh)
      • 14:00
        Alternative subtraction scheme using Nagy Soper Dipoles 30m
        We present a new subtraction scheme, where the subtraction terms have been derived from an improved shower algorithm including quantum interferences. We discuss recent progress in the development of the scheme and show several examples, where the scheme has been applied to processes at lepton and hadron colliders.
        Speaker: Dr Tania Robens (IKTP, TU Dresden)
        Slides
      • 14:30
        Forward Branching Phase Space Generators for NLO Monte Carlos 30m
        Speaker: Walter Giele
        Slides
      • 15:00
        The Matrix Element Method at NLO 30m
        The Matrix element method (MEM) is a widely used tool in experimental analyses since it optimizes the maximal theoretical information (from the Matrix element) and combines this in a meaningful way with detector effects to obtain a likelihood that a particular experimental data set is described by an underlying theoretical model. Most famously the MEM was used in the discovery of the top quark and measure its mass at the Tevatron. However the major drawback of the method is its limitation to leading order matrix elements. This work will illustrate how NLO corrections can be calculated on an event by event basis, providing the ability to define the MEM at NLO.
        Speaker: Ciaran Williams (Fermilab)
        Slides
      • 15:30
        Towards a more accurate prediction of W+b jet production with an automatized approach to one-loop calculations 30m
        We present results for the O(alpha_s) virtual corrections to qg ->W b bbar q' obtained with a new automatized approach to the evaluation of one-loop amplitudes in terms of Feynman diagrams. Together with the O(alpha_s) corrections to q qbar' -> W b bbar g, which can be obtained from our results by crossing symmetry, this represents the bulk of the next-to-leading order virtual QCD corrections to W b bbar + j and W b + j hadronic production, calculated in a fixed-flavor scheme with four light flavors. Furthermore, these corrections represent a well defined and independent subset of the 1-loop amplitudes needed for the NNLO calculation of W b bbar. Our approach was tested against several existing results for NLO amplitudes including selected O(alpha_s) one-loop corrections to W + 3j hadronic production. We discuss the efficiency of our method both with respect to evaluation time and numerical stability.
        Speaker: Dr Laura Reina (CERN)
        Slides
    • 16:00 16:20
      Coffee Break 20m 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
    • 16:20 18:20
      Afternoon 2 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
      Convener: Dr Laura Reina (CERN)
      • 16:20
        One-loop scattering amplitudes from Integrand Reduction 30m
        Speaker: Edoardo Mirabella
        Slides
      • 16:50
        Scattering Amplitudes with Open Loops 30m
        I will present a numerical one-loop algorithm, introduced in arXiv:1111.5206 [hep-ph], which is based on the recursive construction of loop-momentum polynomials called open loops. This novel approach permits to generate one-loop scattering amplitudes for multi-particle processes in a fully automatic and highly efficient way.
        Speaker: Stefano Pozzorini (Universitaet Zuerich (CH))
        Slides
      • 17:20
        Renormalization Group Equations of the Gauge Couplings in the Standard Model at Three-Loop Order 30m
        We present the renormalization group equations of the gauge couplings in the Standard Model at three-loop order in the minimal substraction scheme. We take into account all contributions involving the Standard Model gauge couplings, the top-, bottom- and tau-Yukawa couplings and the Higgs self-coupling. We discuss our prescription of the gamma_5-matrix along with other details of the calculation.
        Speaker: Dr Jens Salomon (Karlsruher Institut für Technologie)
        Slides
      • 17:50
        Assisting LHC Searches Using BlackHat & Sherpa 30m
        Speaker: David Kosower
        Slides
    • 19:00 22:00
      Banquet 3h University Club

      University Club

      U. Pittsburgh

    • 08:30 10:00
      Morning 1 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
      Convener: Ambar Jain (Carnegie Mellon University)
      • 08:30
        ATLAS Top 30m
        Speaker: James Alfred Mueller (University of Pittsburgh (US))
        Slides
      • 09:00
        ttbar+jet: QCD corrections in production and decay 30m
        Speaker: Markus Schulze (Argonne National Laboratory)
        Slides
      • 09:30
        NLO QCD corrections to pp/ppbar->WWbb 30m
        Speaker: Prof. Stefan Dittmaier (Albert-Ludwigs-Universitaet Freiburg (DE))
        Slides
    • 10:00 10:20
      Coffee 20m 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
    • 10:20 12:20
      Morning 2 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
      Convener: Johann Kuehn
      • 10:20
        Top-pair production at NNLO QCD 30m
        I'll present new results for the NNLO corrections to the top-pair production cross-section at the Tevatron.
        Speaker: Alexander Dimitrov Mitov (CERN)
        Slides
      • 10:50
        Towards jet cross sections at NNLO for LHC 30m
        Speaker: Aude Gehrmann-De Ridder (ETH Zurich)
        Slides
      • 11:20
        A subtraction scheme for NNLO hadronic cross sections 30m
        Speaker: Radja Boughezal (Argonne National Laboratory)
        Slides
      • 11:50
        BR( B -> Xs gamma) in 2HDMs to NNLO in QCD 30m
        The rare decay rate B -> Xs gamma provides the strongest bound on the mass of the charged Higgs boson in Two-Higgs Doublet Models (2HDM). In this talk results for the three-loop corrections to the matching coefficients C7 and C8 are presented. They constitute building blocks for the NNLO prediction of BR( B -> Xs gamma) within 2HDM. We describe the calculation in detail and provide numerical results for the branching ratio.
        Speaker: Thomas Hermann (TTP Karlsruhe)
        Slides
    • 12:20 14:00
      Lunch 1h 40m on your own

      on your own

    • 14:00 16:00
      Afternoon 1 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
      Convener: Stefan Dittmaier (MPI fuer Physik)
      • 14:00
        Beyond the SM at the intensity frontier 30m
        Speaker: Michael Ramsey-Musolf (U. Wisconsin-Madison)
        Slides
      • 14:30
        News from the Electroweak SM Fit and Constraints on SM Extensions within Gfitter 30m
        Speaker: Dorthe Kennedy (Deutsches Elektronen-Synchrotron (DE))
        Slides
      • 15:00
        W-boson pair production at the LHC 30m
        W-boson pair production has been studied extensively during the LEP era and has led to a precise determination of the W-mass, width and its couplings. At the LHC, vector-boson pair production will be of similar importance. Due to the high energies accessable at the LHC, combined with high luminosity, the process is a perfect candidate to probe the non-Abelian structure of the Standard Model at the highest energies. Obviously accurate theoretical predictions are need to profit from these experimental possibilities. Results for the full one-loop electroweak corrections to W-boson pair production at hadron colliders will be presented. These corrections bocome large at high transverse momenta. In addiction, photon-induced processes are discussed in detail which contribute with surprisingly large cross sections at high invariant masses of the W-W system. In total, modifications of rates and distributions by several tens of percent are predicted.
        Speaker: Johann Kuehn (Karlsruher Institut fuer Technologie)
        Slides
      • 15:30
        A Formalism for the Systematic Treatment of Rapidity Logarithms in Quantum Field Theory 30m
        We present a formalism for the systematic resummation of a class of logarithms relevant for jet observables in QCD. The logarithms are associated with the rapidities of factorized partons (which are either soft or collinear to specified directions) diverging under certain phase space constraints. The resummation is necessary for a consistent formulation of the perturbation series, and cannot be captured by standard renormalization group techniques. The formalism allows for a consistent merging of resummed corrections with the low energy matrix elements, with full control of the errors in the resummation scheme. Applications to the jet broadening observable and the Higgs transverse momentum cross-sections are outlined.
        Speaker: Mr Duff Neill (Carnegie Mellon University)
        Slides
    • 16:00 16:20
      Coffee 20m 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
    • 16:20 18:20
      Afternoon 2 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
      Convener: Radja Boughezal (Wuerzburg University)
      • 16:20
        Higgs + 1-jet at the LHC at NNLL order 30m
        Speaker: Iain Stewart (MIT)
        Slides
      • 16:50
        Multi-parton next-to-leading order calculations 30m
        Speaker: Sebastian Becker
        Slides
      • 17:20
        Numerical evaluation of multi-loop integrals 30m
        In this talk the new version of the public program SecDec 2.0 for the numerical evaluation of multi-loop integrals with several mass scales is presented. The program is based on sector decomposition to extract dimensionally regulated singularities. To deal with integrable singularities due to mass thresholds, the integration contour is deformed into the complex plane. As applications, numerical results for several two-loop integrals are given, including non-planar two-loop four-point functions entering heavy quark pair production at NNLO.
        Speaker: Sophia Carola Borowka (MPI for Physics Munich)
        Slides
      • 17:50
        Higher-order numerical integration using subtraction terms 30m
        Speaker: Ayres Freitas (University of Pittsburgh)
        Slides
    • 08:30 10:00
      Morning 1 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
      Convener: Sally Dawson (BNL)
      • 08:30
        HELAC-NLO: recent developments and phenomenological results 30m
        Speaker: Dr Giuseppe Bevilacqua (RWTH Aachen)
        Slides
      • 09:00
        Automated one-loop calculations with GoSam 30m
        Speaker: Giovanni Ossola (New York City College of Technology (CUNY))
        Slides
      • 09:30
        Recent progress in aMC@NLO 30m
        Speakers: Rikkert Frederix, Rikkert Frederix (Universitaet Zuerich (CH))
        Slides
    • 10:00 10:20
      Coffee 20m 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
    • 10:20 12:20
      Morning 2 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
      Convener: Prof. Doreen Wackeroth (SUNY Buffalo)
      • 10:20
        Multi-jet physics at the LHC with Blackhat 30m
        I report on recent progress in NLO predictions for multi-jet observables at the LHC, and describe their role in aiding new physics searches.
        Speaker: Kemal Ozeren (UCLA)
        Slides
      • 10:50
        W/Z+jets production at NLO matched with a parton shower 30m
        Speaker: Stefan Hoeche
        Slides
      • 11:20
        A promenade through MadGolem 30m
        With the outstanding performance of the first LHC running stage at 7 TeV, searches for New Physics have started to constrain the allowed parameter space of many of the proposed beyond-the-Standard-Model scenarios. Providing accurate predictions for the major New Physics discovery channels has therefore become a most pressing request to particle phenomenologists these days. MadGolem is a new computational tool that automates the calculation of next-to-leading order (NLO) QCD corrections for heavy particle production in the MadEvent/Golem framework. In this talk we will describe the structure of our code, with particular emphasis on the generation of the renormalized one-loop amplitudes and the automatized subtraction of infrared and on-shell divergences. We will survey the many dedicated tests of all these aspects. Finally, we will describe the user's interface and illustrate how the tool performs in practice.
        Speaker: Dr David Lopez-Val (Heidelberg University)
        Slides
      • 11:50
        MadGolem: applications to New Physics 30m
        In this presentation we will review two recent applications of the fully automized MadGolem package: 1) Squark-Neutralino at NLO QCD: This process has the interesting feature to be a source of monojet signatures, consisting in the production of one hard jet associated with missing transverse energy, been one of the major LHC search channels motivated by many scenarios of physics Beyond the Standard Model. The NLO transverse momentum distributions we have compared with a MLM merged computation and find good agreement for the heavy particles produced. 2) Sgluon pair at NLO QCD: Sgluons are an example of scalar color octet states which arise in a variety of extensions of the Standard Model. They can be fundamental or composite degrees of freedom. In this study we examine the features and quantitative impact of the QCD quantum effects on the production rates and sgluon distributions for the LHC. The NLO sgluon distributions we compare to the matched results for the combined process pp → sgluon pair + jets.
        Speaker: Dorival Goncalves Netto (Heidelberg University)
        Slides
    • 12:20 14:00
      Lunch 1h 40m on your own

      on your own

    • 14:00 16:00
      Afternoon 1 157 Benedum Hall

      157 Benedum Hall

      U. Pittsburgh

      (<a href="https://indico.cern.ch/conferenceDisplay.py/getPic?picId=2&amp;confId=156078" target="_blank">map</a>)
      Convener: Ayres Freitas (University of Pittsburgh)
      • 14:00
        The VINCIA parton shower - present and future 30m
        Speaker: Mathias Ritzmann
        Slides
      • 14:30
        NLL soft and Coulomb resummation for squark and gluino production at the LHC. 30m
        We present predictions of the total production cross sections of pairs of squarks and gluinos at the LHC, which incorporate a combined resummation of soft logarithms and Coulomb singularities, including bound-state contributions. These terms dominate the threshold region of the partonic cross section and are resummed directly in momentum space using an effective-theory framework based on SCET and pNRQCD. This differs from the more conventional approach where soft logarithms are exponentiated in Mellin-moment space. The combined resummation of soft and Coulomb corrections can lead to much bigger effects than soft resummation alone, with corrections of up to 120% to the fixed-order NLO result for gluino-gluino production at 7 TeV, and smaller (but still sizeable) effects for the other production processes. The theoretical uncertainty of the cross sections is typically reduced to about \pm 10%.
        Speaker: Christopher Wever (University Utrecht)
        Slides
      • 15:00
        HERWIRI 1 and 2: Amplitude-Based Resummation in Precision Hadron Scattering 30m
        We present comparisons of HERWIRI1 to experimental data showing the effect of its IR-improved kernels in both HERWIG6.5 and MC@NLO environments. We also present the first complete implementation of HERWIRI2, which incorporates the order-alpha electroweak corrections and coherent exclusive exponentiation structure of the KK Monte Carlo in a HERWIG environment for Z production. We discuss its current status and results, and sketch future upgrades.
        Speaker: Scott Yost (The Citadel)
        Slides
      • 15:30
        Summary and Outlook 30m
        Speaker: Zvi Bern (Univ. of California Los Angeles (US))
        Slides
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