School on QCD and LHC Physics

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Start time: July  22, 2015

Ends on: July 31, 2015

Location: São Paulo, Brazil

Venue: IFT-UNESP

Organizers / Lecturers:

  • Fernando Febres Cordero (Freiburg University, Germany)
  • Daniel de Florian (FCEyN – Universidad de Buenos Aires, Argentina)
  • David A. Kosower (Saclay, France)
  • Rogério Rosenfeld (IFT-UNESP / ICTP-SAIFR, Brazil)

Invited Lecturers:

  • Zvi Bern (UCLA, USA): On-shell methods
  • Claude Duhr (Université Catholique de Louvain, Belgium): Precision Higgs
  • Johannes Henn (IAS – Princeton, USA): Feynman Integrals
  • Stefan Prestel (SLAC, USA): Parton Showers
  • Gavin Salam (CERN, Switzerland): Basics of QCD
  • Andre Sznajder (UERJ, Brazil): LHC searches and Higgs results
  • Febres Cordero/de Florian/Kosower: Higher-Order Calculations

Description:

With the start of Run II of the LHC, 2015 will be an exciting year for high-energy physics, posing new experimental and also theoretical challenges. Recent years have witnessed important advances in our ability to provide predictions for the increasingly complex final states that are of key importance to the LHC physics program. These advances draw on our greatly improved understanding of the structure of scattering amplitudes in gauge theories.
This school is aimed at preparing graduate students for theoretical research in quantum chromodynamics as applied to the future research program at the LHC. Aspects of the school will also be valuable to younger postdoctoral fellows and graduate students in experimental high-energy physics. Attendees are invited to present their research activities in a poster session. There is no registration fee and limited funds are available for travel and local expenses. 

 Announcement

QCDandLHC

List of Participants: Updated on July 13

School Program:

Satisfaction Survey

Files:

*Files of Zvi Bern and Johannes Henn are not available, since both used the blackboard for their lectures.

 

 Videos:

Photos:

Lectures Summary:

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Zvi Bern (UCLA): On-Shell Methods
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On-shell methods will be covered.  This includes on-shell recursion and unitarity.  Explicit examples showing how amplitudes relevant for collider physics can be constructed with these methods will be worked out.

References:

  1. H. Ita, “Susy Theories and QCD: Numerical Approaches,” J.\ Phys.\ A{\bf 44}, 454005 (2011)  [arXiv:1109.6527 [hep-th]].
  2. H. Elvang and Y. t. Huang, “Scattering Amplitudes”, arXiv:1308.1697 [hep-th].
  3. Sections on on-shell method in new book from Matt Schwartz: “Quantum Field Theory and the Standard Model”

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Claude Duhr (Université Catholique de Louvain): Precision Higgs
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Determining the properties of the recently discovered Higgs boson is one of the main challenges for the Run II of the LHC. In these lectures we discuss the role played by higher-order corrections in this context. Indeed, Higgs observables are generically plagued by large quantum corrections, making the knowledge of corrections at NNLO and even beyond a necessity in order to obtain reliable theoretical predictions. We review the techniques required to compute inclusive Higgs observables to higher orders, and we also comment on first steps towards the exclusive computation of Higgs observables at NNLO.

References:

  1. L. Reina, “TASI 2011: lectures on Higgs-Boson Physics”, arXiv:1208.5504

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Johannes Henn (IAS – Princeton): Feynman Integrals
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At the Large Hadron Collider (LHC), our current best theoretical understanding of particle physics is being tested against experiment, by measuring e.g. properties of the recently discovered Higgs boson. With run 2 of the LHC, experimental accuracy will further increase, making better theoretical predictions necessary. Obtaining the latter involves difficult higher-order calculations of scattering amplitudes and cross sections in quantum field theory. One of the major challenges is the evaluation of Feynman multi-loop integrals, which typically depend on several scales. Recently, much progress has come from generalizing new ideas on loop integrands from supersymmetric field theories to QCD, and combining them with the differential equations method. In these lectures we will give an introduction to modern methods for computing Feynman integrals, focusing on recent advances based on differential equations.

References:

  1. J.M. Henn, ‘Lectures on differential equations for Feynman integrals’, arXiv:1412.2296 [hep-ph].
  2. N. Arkani-Hamed, J.L. Bourjaily, F. Cachazo, J. Trnka, ‘Local Integrals for Planar Scattering Amplitudes’, arXiv:1012.6032 [hep-th], JHEP 1206 (2012) 125.
  3. J.M. Henn, ‘Multiloop integrals in dimensional regularization made simple’, arXiv:1304.1806 [hep-th], Phys. Rev. Lett. 110 (2013) 25, 251601.

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Stefan Prestel (SLAC): Parton Showers
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This lecture aims at describing how realistic collider events can be produced with numerical methods, focusing on General Purpose Event Generators in particular. This includes 1) a brief sketch of numerical integration techniques, 2) a more detailed description of parton showers and their connection to all-order resummation, 3) a discussion of improvement strategies, and 4) a short outline of the modeling of non-perturbative and multi-particle effects in hadron collisions.

References:

  1. Peter Skands, TASI lectures http://inspirehep.net/record/1121892
  2. Stefan Hoeche, TASI  lectures https://sites.google.com/a/colorado.edu/tasi2014wiki/lecture-topics/parton-showers-and-monte-carlo-simulations

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Gavin Salam (CERN): Basics of QCD
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These lectures will cover some of the essential ideas of QCD for colliders. They will discuss infrared and collinear divergences in perturbative QCD, show how these, together with non-perturbative physics are responsible for the structure of events at colliders. They will also introduce the main ingredients and tools that are available for making precise predictions at colliders, including a discussion of parton distribution functions.

References:

1. QCD and Collider Physics, by Ellis, Stirling and Webber, CambridgeUniversity Press.
2. Introduction to QCD, by P. Skands,http://arxiv.org/abs/arXiv:1207.2389
3. Elements of QCD for hadron colliders, G. P. Salam,http://arxiv.org/abs/arXiv:1011.5131

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Andre Sznajder (UERJ): LHC searches and Higgs results
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In these lectures we present a review of the LHC experimental results on the SM Higgs boson searches and the observed properties of a Higgs boson with a mass near 125 GeV.  Comprehensive sets of production and decay measurements are combined, where the decay channels include gamma gamma, ZZ, WW, tau tau, bb, and mu mu pairs. The data samples were collected in 2011 and 2012 and correspond to a total of about 25 fb-1 from pp collisions at 7 and 8 TeV.  We also present a short summary of BSM searches.

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Febres Cordero / de Florian / Kosower: Higher-Order Calculations
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We present an introduction to jet calculations at colliders with focus on higher order corrections in QCD. We discuss the structure of differential cross sections at the first few orders in QCD; subtraction methods at NLO; the KLN theorem, and related topics. The lab session will give an introduction to practical calculations with modern automated tools.

References:

1. QCD and Collider Physics, by Ellis, Stirling and Webber, CambridgeUniversity Press.
2. G. Dissertori, I. Knowles and M. Schmelling, Quantum Chromodynamics, High Energy Experiments and Theory.
3. T. D. Lee and M. Nauenberg, http://dx.doi.org/10.1103/PhysRev.133.B1549
4. S. Catani and M. Seymour, http://arxiv.org/abs/hep-ph/9605323

Additional Information:
Registration: ALL participants should register. The registration will be on July 22 at the institute from 10:45 to 11:45 am.
You can find arrival instruction at http://www.ictp-saifr.org/?page_id=195
BOARDING PASS: All participants, whose travel has been provided or will be reimbursed by the institute, should bring the boarding pass upon registration, and collect an envelope to send the return boarding pass to the institute.

Accommodation: Participants whose accommodation has been provided by the institute will stay at  The Universe Flat. Each participant whose accommodation has been provided by the institute has received the details on the accommodation individually by email.
Emergency number: 9 8233 8671 (from São Paulo city); +55 11 9 8233 8671 (from abroad), 11 9 8233 8671 (from outside São Paulo).
Ground transportation instructions: