Higgs Physics

Abstract

Understanding the nature of electroweak symmetry breaking—or slightly more specifically deciphering the Higgs mechanism—is the main goal of the ATLAS and CMS experiments at the LHC. Observing some kind of Higgs boson and studying its properties involves many experimental and theoretical issues focused around understanding hadron collider data and QCD predictions to unprecedented precision. The latter will be the main topic of the second half of this lecture.

Further Reading

At this point we are done with our brief review of the Higgs sector in the Standard Model and of contemporary Higgs phenomenology. From the discussions it should be clear that we have to move on to QCD, to understand the strengths and weaknesses of these searches and what distinguishes a good from a bad search channel.

Before moving on we mention a few papers where you can learn more about Higgs phenomenology at the LHC. Luckily, for Higgs searches there are several very complete and useful reviews available:

• You can look at the original articles by Higgs [23, 24] or Brout and Englert [17], but they are rather short and not really on top of the phenomenological aspects of the topic. Other papers for example by Guralnik, Hagen, Kibble [20] tend to be harder to read for phenomenologically interested students.

• Wolfgang Kilian’s book [26] on the effective field theory approach to the Higgs mechanism is what the corresponding sections in these lecture notes are largely based on it. The underlying symmetry structure, including the custodial symmetry is nicely described in Scott Willenbrock’s TASI lectures [38].

• If you are interested in a comprehensive overview of Higgs physics as an effective field theory with a special focus on higher–dimensional operators in linear and non–linear sigma models there is a really useful paper from Spain [8].

• Abdelhak Djouadi’s compilation on ‘absolutely everything we know about Higgs phenomenology’ is indeed exhaustive. It has two volumes, one on the Standard Model [15] and another one on its minimal supersymmetric extension [16]

• For more experimental details you might want to have a look at Karl Jakobs’ and Volker Büscher’s review of LHC Higgs physics [9].

• As a theory view on LHC Higgs physics, mostly focused on gluon fusion production and its QCD aspects, there is Michael Spira’s classic [35]. This is where you can find more information on the low energy theorem. Michael and his collaborators also published a set of lecture notes on Higgs physics [19].

• As always, there is a TASI lecture on the topic. TASI lecture notes are generally what you should look for when you are interested in an area of high energy physics. Dave Rainwater did not only write his thesis on Higgs searches in weak boson fusion [31], he also left us all he knows about Higgs phenomenology at the LHC in his TASI notes [32].

• Tao Han wrote a very comprehensible set of TASI lecture notes on basic LHC phenomenology, in case you need to catch up on this [22].

• For some information on electroweak precision data and the ρ parameter, there are James Wells’ TASI lectures [36].

• If you are interested in Higgs production in association with a W or Z boson and the way to observe boosted $H \rightarrow b\bar{b}$ decays you need to read the original paper [11]. The same is true for the $t\bar{t}H$ analysis.

• For cut rules and scalar integrals the best writeup I know is Wim Beenakker’s PhD thesis. Unfortunately, I am not sure where to get it from except from the author by request.

• If you are getting interested in fixed points in RGE analyses you can look at Christoph Wetterich’s original paper [37] or a nice introductory review by Barbara Schrempp and Michael Wimmer [34].

• My discussion on technicolor largely follows the extensive review by Chris Hill and Elisabeth Simmons [25].

• A really nice writeup which my little Higgs discussion is based on is Martin Schmaltz’ and David Tucker–Smith’s review article [33].

• For more information on Higgs inflation you can start with a nice set of TASI lectures on inflation [4] and then dive into a specific review of Higgs inflation by one of its inventors [7].