lecture High Precision for Hard Processes at the LHC
Date/Time: from Wednesday, 6 September 2006 (09:00) to Friday, 8 September 2006 (18:10) (Europe/Zurich)
Location: ETH Zurich
Chairperson:
Description: HP2 workshop home page
Wednesday, 6 September 2006 09:00 ->18:25 Day 1    
Thursday, 7 September 2006 09:00 ->18:00 Day 2    
Friday, 8 September 2006 09:00 ->18:10 Day 3    

 
 Wednesday, 6 September 2006
Day 1 (09:00 ->18:25 )
Chairperson:
 09:00
Road to the LHC: passing by the Tevatron (40')   Slides pdf file   Joey Huston (Michigan)  
 09:40
Latest results from MC@NLO (25')   Slides pdf file   Bryan Webber (Cambridge)  
 10:05
The Unitarity Bootstrap for QCD Loop Amplitudes (25')   Slides powerpoint file   David Kosower (Saclay)  
10:30  Coffee (30')
 11:00
Higgs+dijets production at NLO with semi-numerical methods (25')   Slides pdf file   Giulia Zanderighi (CERN)  
 11:25
Can we find a computationally efficient loop algorithm? (25')   Slides pdf file   Giampiero Passarino (Torino)  
Even disregarding the intrinsic necessity of some new
algorithm for numerical evaluation of one-loop diagrams, and
even in case it has no intrinsic necessity at all, a
probable decision about its goodness is possible inductively
by studying its success. Success here means fruitfulness in
consequences, in particular in verifiable consequences,
i.e., consequences demonstrable without the new algorithm,
whose proofs with the help of the new algorithm, however,
are considerably simpler and easier to discover, and make it
possible to contract into one proof many different proofs.
 11:50
Precise predictions for the Higgs-boson decay H -> WW/ZZ -> 4 fermions (25')   Slides pdf file   Ansgar Denner (PSI Zurich)  
The decay of the Standard Model Higgs boson into four
fermions via a virtual W-boson or Z-boson pair is one of the
most important
decay modes in the Higgs-boson search at the LHC. We present
a calculation of the first order radiative corrections to
these processes, including higher order improvements. The
intermediate W- and Z-boson resonances are consistently
described using the complex mass scheme, which is explained
in the talk.  Numerical results for partial decay widths and
angular and invariant-mass distributions are shown.
12:15  Lunch (1h45')
 14:00
Numerical evaluation of one-loop amplitudes (25')   Slides pdf file   David Soper (Oregon)  
 14:25
Automated QCD calculations at NLO (25')   Slides pdf file   Stefan Weinzierl (Mainz)  
I will discuss various technical aspects related to automated
QCD calculations at NLO:
- the recursive calculation of amplitudes,
- the organization of the colour structures,
- the automated generation of subtraction terms,
- the numerical tensor reduction of loop integrals.
 14:50
Unitarity Cuts and QCD Loop Amplitudes (25')   Slides pdf file   Ruth Britto (Amsterdam)  
15:15  Coffee (20')
 15:35
Loop amplitudes from MHV diagrams (I) (25')   Slides pdf file   Gabriele Travaglini (Queen Mary)  
 16:00
Exclusive Drell-Yan production at NN LO (25')   Slides pdf file   William Kilgore (Brookhaven)  
I describe a parton-level Monte Carlo calculation of Drell-Yan
  production at next-to-next-to-leading order.  The calculation is
  performed with a subtraction scheme in which the subtraction term is
  the squared matrix element itself.
 16:25
Status of NNLO corrections to e+e- -> 3j (25')   Slides pdf file   Thomas Gehrmann (Uni Zurich)  
16:50  Coffee (20')
 17:10
Computing one-loop amplitudes at the integrand level (25')   Slides pdf file   Roberto Pittau (Torino)  
We show how to extract the coefficients of the 4-, 3-, 2-
and 1-point one-loop scalar integrals from the full one-loop
amplitude of arbitrary scattering processes. In a similar
fashion, also the rational terms can be derived. Basically no
information on the analytical structure of the amplitude is
required,
making our method appealing for an efficient numerical
implementation.
 17:35
Higgs Production via Gluon Fusion: QCD corrections to Squark Loops (25')   Slides pdf file   Michael Spira (PSI)  
The loop-induced processes gg -> h,H,A provide the dominant Higgs boson
production mechanisms at the Tevatron and LHC in a large range of the
minimal supersymmetric extension of the Standard Model. For squark
masses below ~400 GeV squark loop contributions become important in
addition to the top and bottom quark loops. The two-loop QCD corrections
to the squark contributions of these processes are determined including
the full squark and Higgs mass dependences. They turn out to be of
O(10-100%) and thus important for the Tevatron and LHC experiments.
Squark mass effects of the K factors can be of O(20-30%).
 18:00
QCD corrections to vector-boson fusion processes (25')   Slides pdf file   Carlo Oleari (Bicocca, Milano)  


 
 Thursday, 7 September 2006
Day 2 (09:00 ->18:00 )
Chairperson:
 09:00
Prospects for measurements of hard scattering processes at the LHC (40')   Slides pdf file   Guenther Dissertori (ETH Zurich)  
After a very brief report on the status of the LHC preparations
(machine and detectors) I will try to summarize the current
understanding of how well specific hard scattering processes 
can be measured at the LHC, and what the relevance of these
measurements is. Examples are the Drell-Yan process, 
top production,  W/Z + jet as well as inclusive jet production.
 09:40
PDF issues at LHC (25')   Slides powerpoint file pdf file   W. James Stirling (Durham)  
 10:05
The two-loop anomalous dimension matrix for soft gluon exchange (25')   Slides powerpoint file pdf file   Lance Dixon (SLAC)  
Resummation of soft-gluon exchange for QCD hard scattering
requires an anomalous dimension matrix in color space.
We compute this matrix directly for arbitrary massless 
processes for the first time at two loops, and
show that it is proportional to the one-loop matrix.  
This result reproduces the 1/eps pole terms in previous explicit
two-loop computations, and predicts such terms for arbitrary processes.
The proportionality of the one- and two-loop matrices 
also makes it possible to resum in closed form the
next-to-next-to-leading logarithms for arbitrary processes.
10:30  Coffee (30')
 11:00
Recent progress in splitting functions (25')   Slides pdf file   Sven Moch (DESY Zeuthen)  
 11:25
Multi-loop parton distributions for large and small x (25')   Slides pdf file   Giuseppe Marchesini (Bicocca, Milano)  
 11:50
NLO + Shower: a new approach (25')   Slides pdf file   Paolo Nason (Bicocca, Milano)  
12:15  Lunch (1h45')
 14:00
Techniques for one-loop tensor integrals in many-particle processes (25')   Slides pdf file   Stefan Dittmaier (MPI, Munich)  
In the calculation of NLO corrections to multi-leg processes serious numerical
problems arise in the commonly used Passarino-Veltman reduction of tensor to
scalar integrals in exceptional phase-space configurations.
In this talk two alternative methods are discussed solving this problem.
One of the methods relies on a seminumerical approach, in which a specific
tensor coefficient is evaluated numerically, replacing the standard scalar
integral in the list of basis integrals. The other method makes use of
expansions in terms of small Gram and (if needed) other kinematical
determinants. Both procedures have been successfully applied to the NLO
electroweak corrections to e+e- --> 4fermions.
 14:25
Higgs + 2 jet signals from gluon fusion (25')   Slides pdf file   Dieter Zeppenfeld (Karlsruhe)  
 14:50
Recursive equations for arbitrary scattering processes (25')   Slides pdf file   Costas Papadopoulos (Demokritos Athens)  
15:15  Coffee (20')
 15:35
NLO corrections to $pp/pbar p to tbar t + jet + X$ (25')   Slides pdf file   Peter Uwer (CERN)  
 16:00
Threshold resummation for high-transverse-momentum Higgs production (25')   Slides pdf file   Daniel de Florian (Buenos Aires)  
We perform the all-order resummation of large logarithmic(NLL)
QCD corrections for the process pp ->H+ X when the Higgs boson H is
produced at high transverse momentum.
 16:25
The GOLEM project: status and applications (25')   Slides pdf file   Thomas Binoth (Edinburgh)  
In this talk I review the status of our GOLEM project. The acronym stands 
for "General One-Loop Evaluator of Matrix-elements". This tool is designed 
to allow for an efficient and numerically stable evaluation of multi-particle
one-loop amplitudes which are needed for the precise description of 
numerous processes relevant for the upcoming LHC. First applications are presented.
16:50  Coffee (20')
 17:10
Soft-gluon effects in WW production at hadron colliders (25')   Massimiliano Grazzini (INFN, Firenze)  
 17:35
Madgraph beyond the Standard Model (25')   Slides pdf file   Tilman Plehn (Edinburgh)  
Madgraph and Madevent are a well established tool to evaluate tree-level
amplitudes and create unweighted events for processes with a large number
of external particles at the LHC. For the Madgraph collaboration I review
the status, some physics complications and recent calculations of
Madgraph/Madevent for physics beyond the Standard Model.


 
 Friday, 8 September 2006
Day 3 (09:00 ->18:10 )
Chairperson:
 09:00
Beyond the Standard Model Physics at the LHC (40')   Slides pdf file   Alex Pomarol (Barcelona)  
 09:40
The dipole-antenna approach to shower monte carlo's (25')   Slides powerpoint file pdf file   Walter Giele (Fermilab)  
 10:05
A new method to compute multileg one-loop cross sections (25')   Slides pdf file   Stefano Catani (INFN, Firenze)  
10:30  Coffee (30')
 11:00
Twistor Inspired Higgs Phenomenology (25')   Slides pdf file   Nigel Glover (Durham)  
We discuss how the twistor inspired methods can be used to derive compact
expressions for multi-parton amplitudes involving Higgs bosons (in the
limit that the top quark mass is heavy producing an effective Higgs-gluon
interaction).
 11:25
Loop amplitudes from MHV diagrams (II) (25')   Slides pdf file   Andreas Brandhuber (Queen Mary)  
 11:50
Reduction with spinor formalism (25')   Slides pdf file   Bo Feng (Imperial College)  
12:15  Lunch (1h45')
 14:00
All-multiplicity amplitudes in QCD (25')   Slides powerpoint file pdf filedown arrow   Darren Forde (Saclay)  
I will discuss the construction of amplitudes at one-loop in QCD using
the unitarity bootstrap approach. I will detail the techniques needed to
build the rational contributions to these amplitudes as well as
highlighting not only their application to fixed-multiplicity amplitudes
but also to all-multiplicity amplitudes.
 14:25
The Rational Part of QCD Amplitudes (25')   Slides pdf file   Chuan-jie Zhu (Beijing)  
 14:50
On the IR singularities of massive QCD amplitudes beyond one loop (25')   Slides pdf file   Alexander Mitov (DESY Zeuthen)  
15:15  Coffee (20')
 15:35
A subtraction scheme for cross sections at NNLO (25')   Slides pdf file   Vittorio del Duca (INFN, Torino)  
 16:00
Towards event shapes by NNLO subtraction (25')   Slides pdf file   Gabor Somogyi (Debrecen)  
 16:25
Techniques and Results for Supergravity Calculations (25')   Slides powerpoint file pdf file   David Dunbar (Swansea)  
The recent progress for calculating gauge theory amplitudes may
also be applied to gravity calculations.  We find surprising
similarities between the perturbative  expansions of maximally
supersymmetric Yang-Mills and gravity theories.  We discuss possible
implications of these results for the UV behaviour of supergravity in D=4.
16:50  Coffee (20')
 17:10
Prospects for the Future (1h0')   Slides powerpoint file pdf file   Zvi Bern (UCLA)