Who cares about particle physics? : making sense of the Higgs boson, the Large Hadron Collider and CERN

267 Pages·2016·25.8 MB·English

by  Gagnon

WHO CARES ABOUT PARTICLE PHYSICS?

WHO CARES
ABOUT
PARTICLE
PHYSICS?
Making Sense of the Higgs Boson, the Large
Hadron Collider and CERN
Pauline Gagnon
Indiana University,
USA
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3
Great Clarendon Street, Oxford, OX2 6DP,
United Kingdom
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© Pauline Gagnon 2016
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First Edition published in 2016
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To my parents, Colette Perron and Paul Gagnon, who gave me so much, and to my
friends Kate Hieke and Cath Noyes, both gone way too early.

Acknowledgments
If you are like me, you may like reading the acknowledgments at the
beginning of a book just to glimpse at what the author might have gone
through. This being my first book, I was especially afraid of feeling iso-
lated after relocating 500 km away from CERN, where I had spent the
previous 19 years. However, thanks to the incredible support I received
from colleagues and friends, it was quite the opposite. Even when I was
sitting alone at my desk, they were by my side, albeit virtually and elec-
tronically, revising one or several chapters, or offering me advice and
encouragement. This was so much so that, in the end, I had the im-
pression of having achieved some teamwork. It was really reassuring
for a person like me, used to working with 3000 other people on the
ATLAS experiment. I was not completely surprised, though, knowing
that the vast majority of my colleagues are just as eager as me to share
the chance we have to participate in the unique adventure taking place
at CERN right now.
I want to thank profusely (and in alphabetical order) Sylvie Brunet,
Natalie Garde, Penny Kasper, Narei Lorenzo and Pascal Pralavorio for
reviewing the whole book or most of it, offering me invaluable advice
and suggestions about both the content and its presentation. Being able
to count on their assistance made a whole amount of difference. Several
other colleagues and friends also checked one or several chapters for
scientific accuracy or clarity. I am therefore very grateful to Alexandre
Arbey, Sudeshna Banerjee, Thomas Cocolios, Michael Doser, Monica
Dunford, Louis Fayard, Jules Gascon, James Gillies, Geneviève Guinot,
Vincenzo Iacoliello, Marumi Kado, Clara Kulich, Nazila Mahmoudi,
Sophie Malavoy, Judita Mamuzic, Giampiero Mancinelli, Django Man-
glunki, Markus Nordberg, Marie-Claude Pugin, Yves Lagacé, Pierre
Savard and Andrée Robichaud-Véronneau for their time and for their
excellent suggestions for improvement. Their generous help and sup-
port were thoroughly heartwarming. Thanks to them, there should be
many fewer mistakes, and the text is much more fluid. They took time
off from their evenings, their weekends and even their holidays to assist
me. I am immensely grateful to all of them.
Huge thanks also go to Kate Kahle for believing in this project from
the start and for her sustained support up to the end. I am also very
viii Acknowledgments
grateful to all my friends who joined me for e-lunches on Skype. I also
wish to thank Jean-Marc Gagnon from MultiMondes, my editor for the
French edition, for his extremely enthusiastic response when I first con-
tacted him as well as Ania Wronski from Oxford University Press for
her professionalism, her sound advice and her patience throughout the
editorial process.
Special thanks go to my mother for her Larousse dictionary and her
Bescherelle grammar book, and for passing on to me her taste for well-
done work. Finally, I wish to thank my partner, Marion Hamm, for her
patience, her love and her multiple encouragements, especially for in-
sisting I stray away from my computer to get some fresh air. Otherwise,
I would certainly look like a Higgs boson in the middle of winter.
Chapter Summaries
Chapter 1: What Is Matter Made Of?
What are the smallest grains of matter, and how do they interact to
form all the matter that we observe around us? The Standard Model is
the current theoretical model that describes all these particles and their
interactions, giving us a clear representation of the material world. It
can even predict the behavior of these particles to a very high level of ac-
curacy. Each one of these particles also comes with its own antiparticle.
However, nearly all the antimatter has mysteriously disappeared from
our Universe.
Chapter 2: What about the Higgs Boson?
The media have relayed the message that the Higgs boson gives
mass to fundamental particles. In fact, three elements are needed to
generate the masses of fundamental particles: a mechanism, a field
and a boson. The Brout–Englert–Higgs mechanism is a mathemati-
cal formalism that describes by means of equations a real physical
entity, the Brout–Englert–Higgs field. This field is simply one of the
properties of our Universe, like space and time are. The Higgs boson
is an excitation of this field, just as a wave is an excitation of the
surface of the ocean. Finding the Higgs boson proved the existence
of this field.
Chapter 3: Accelerators and Detectors:
The Essential Tools
Producing Higgs bosons was one goal of the Large Hadron Collider, or
LHC, at CERN. It first accelerates protons to almost the speed of light,
and then brings them into collision. This accelerator can concentrate
a huge quantity of energy into an extremely small point in space. The
energy generated materializes in the form of particles. Most of these
particles are unstable and break apart moments after appearing. Detec-
tors located at the collision points act as huge cameras to catch the frag-
ments of these ephemeral particles.