The Asymmetry between Matter and Antimatter

The Asymmetry between Matter and

Antimatter

Besma M’charekFEW, Vrije Universiteit Amsterdam

The asymmetry between matter and antimatter

2

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”


3

Matterq

uark

sele

ctronNucleusneutron

proton

atom

Matter/antiMatter


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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,τ,νe,νμ,ντ).

• 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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EM

EW

Where is the antimatter?

life

13.7 billion y

1st stars

1 billion y

3000K

300,000 y

H/He

300 s106 s1011 s

matter +antimatter

< 1011 sA

atom

nucleushadrons


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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 +

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

=>In weak interactions, parity symmetry is always violated

=>In weak interactions, charge symmetry is always violated

=>In weak interactions, CP is almost never violatedalmost


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P

P

C C

Escher on CP violation…

CP


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Weak interactions

A main difference between electromagnetic and weak interactions is in the coupling

constants ge and gubeiγ , ..• 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

photon

ge

gubeiγ

u

b

Weak interactions

Electromagnetic interactions

W+

ie


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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-quarkB-

mesons

B

s s

s s

s s

s s

B D K

B D K

B D K

B D K

B B


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CERN

4.4 km

1989-2000 LEP e+e (88-209 GeV)2007-2015 LHC pp (14000 GeV)

LHCb

Atlas

Alice

CMS


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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 γ


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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

=>There was an equal amount of matter and anitmatter


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The CKM-matrix and the γ-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. .

ud us ub

cd cs cb

td ts tb

V V V

V V V

V V V

iub

it

ud us

cd cs cb

ts tbd

V e

V e

V V

V V V

V V


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Proposed project

• Improving the reconstruction program

• Developing the selection procedure of the Bs->DsK events

• Developing the fitting method in order to obtain the γ-parameter from the selected events

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The Asymmetry between Matter and Antimatter