The Asymmetry between Matter and Antimatter

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The Asymmetry between Matter and Antimatter

• Besma Mcharek
• FEW, Vrije Universiteit Amsterdam

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Outline

• The Standard Model of Physics and asymmetry
  between matter and antimatter
• Charge Parity (CP) violation.
• Measuring CP violation with the LHCb detector at
  CERN Geneva.
• Summary.

Matter /antimatter asymmetry
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Matter
Matter/antiMatter
quarks
electron
Nucleus
neutron proton
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The Standard Model

• The fundamental building block of matter consists
  of 6 quarks (u, d, c, s, t, b)
• 6 leptons (e,µ,t,?e,?µ,?t).
• These particles interact through four difference
  forces
• electromagnetic
• strong forces
• weak forces
• gravity

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Where is the antimatter?
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Where is the antimatter?
13.7 billion y
1 billion y
300,000 y
300 s
10?6 s
10?11 s
lt 10?11 sA
3000K
life
1st stars
H/He
matter antimatter
EM
EW
hadrons
nucleus
atom
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Charge Parity symmetry

• Parity symmetry
• Parity P reflects a system into its mirror-image
• What if your image behaves differently than you??

• Charge symmetry
• Charge conjugation C changes the electric charge
  of the particle.
• e ? e -
• K - ? K

gtIn weak interactions, charge symmetry is always
violated
gtIn weak interactions, parity symmetry is always
violated

• Charge Parity symmetry
• Changes a particle into its antiparticle.

gtIn weak interactions, CP is almost never
violated
almost
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Escher on CP violation
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Weak interactions

• A main difference between
• electromagnetic and weak
• interactions is in the coupling
• constants ge and gubei? , ..
• 1 for the electromagnetic
• 9 for the weak
• Weak interactions can change quark flavors (
  e.g. from up u to bottom b).
• Mixing of quarks

Electromagnetic interactions
W
Weak interactions
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B-mesons in the LHCb detector

• B-mesons mix to
• In the LHCb detector, we want to study weak
  interaction with the special B-decays

Two quarks, one is always a b-quark
B-mesons
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CERN
1989-2000 LEP ee? (88-209 GeV)
2007-2015 LHC pp (14000 GeV)
LHCb
? 4.4 km
CMS
Atlas
Alice
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The LHCb detector
The detector
Results
Simulation and Reconstruction
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Summary

• In the universe, there is an asymmetry between
  matter and antimatter.
• We need CP-symmetry breaking in order to explain
  this asymmetry.
• We will use the LHCb detector and study the decay
  of B-mesons (abundant in this detector).
• We will measure the parameter ?

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Additional slides!!!
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History of our universe

• First the universe was hot and compact a soup of
  energetic photons and massive particles.
• The laws of physics allow a sufficiently
  energetic photon to create a particle/antiparticle
  pair and a particle/antiparticle pair can
  annihilate into an energetic photon.
• Annihilation and Creation happened continuously
• gtThere was an equal amount of matter and
  anitmatter

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The CKM-matrix and the ?-parameter

• The mixing of quarks in weak interactions is
  described by the CKM-matrix.
• The complex Vxy entries of the matrix are the
  nine gw parameters.
• The matrix can be written in a way that only two
  entries are left complex arguments. The arguments
  of those two entries are measurable.
• We want to measure one of these entries. .

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Proposed project

• Improving the reconstruction program
• Developing the selection procedure of the Bs-gtDsK
  events
• Developing the fitting method in order to obtain
  the ?-parameter from the selected events