QCD for the LHC
Gregory Soyez
Here is a brief list of the topics that will be addressed in the lectures.
- Foreword
From a generic picture of collisions at the LHC, I will identify
the different parts that one needs to understand in order to
control the QCD processes in hadronic collisions.
- QCD in e^{+} e^{-} collisions
Because of their simplicity, e^{+} e^{-}
collisions provide a perfect playground to study the QCD final
state. It thus allows to address many of the problems that we will
face (in a more complicated way) for LHC collisions. Among them, I
will discuss
- the e^{+} e^{-} -> qq process and
its first O(α_{s})
corrections e^{+} e^{-} -> qqg,
- the QCD soft and collinear divergences that arise from
gluon emissions, and various interesting consequences,
- event shapes variables which are a fundamental test of
QCD,
- the definition of jets in e^{+}
e^{-} collisions that will be discussed at
length.
Notes are available here
- QCD in DIS
DIS i.e. lepton-hadron collisions are the most important
constraints on the Parton Distribution Functions (PDF) that are
fundamental objects in the description of pp
collisions. This covers the following points:
- a brief introduction to DIS, PDF and Bjorken scaling,
- a derivation of the DGLAP evolution equations, e.g.
the QCD scaling violations, and the solutions to these
equations,
- a discussion of the factorisation theorem and the
resummations of collinear singularities to all orders achieved
by the DGLAP equation,
- how PDF are extracted from experimental data.
Notes are available here
- QCD in pp collisions
QCD appears at various levels in pp collisions. I will try to
review most of the information that will be relevant at the LHC by
relating it to the information one can get from e^{+}
e^{-} collisions, DIS or previous studies at the
Tevatron, but also to what extend LHC will be different from those
previous experiments. This includes the following topics:
- the basic kinematics for pp collisions (somewhat
different from e^{+} e^{-} and
DIS),
- the role that the PDF and, in particular, their
uncertainties will play at the LHC,
- Drell-Yan and jet production at lowest order (and a bit of
Drell-Yan at NLO),
- a brief overview of computations of multi-leg and NLO
matrix elements,
- an extensive description of how to define jets in a
hadronic environment.
Notes are available here
For each of the subjects approached in the lectures, I will try to
illustrate them by some of their experimental implications or
observations.
Practical information
- Location: Universite Catholique de Louvain (UCL), Centre for Particle Physics Phenomenology (CP3)
- Schedule: Monday Decembre 15 - Friday December 19, 10-12am (except Dec 18: 8:30-10:30am)
Additional notes
A similar series of lectures was given in other contexts where the material provided here can also be used as a decent reference:
- another iteration at the Universite Catholique de Louvain (UCL) in December 2015. Modulo a slightly more modern coverage of pp collisions, this followed relatively closely the above material
- Other lectures focalised on jets have used the "jet" material of the e^{+} e^{-} and pp collisions described above. (see here for a list))
- a series of lectures on QCD and colliders given at the GGI (see the school website for details and videos). Apart from the fact that I did not go into the details of the calculations, the e^{+} e^{-} and DIS parts followed the above material. The pp part of the lecctures (last 2 lectures) deviated more substantially from what is linked above. I can add a scanned copy of my notes upon request.
Contact: Gregory Soyez