The Asymmetry between Matter and Antimatter Besma M’charek FEW, 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”

The asymmetry between matter and antimatter 3 Matter quarks electron Nucleus neutron proton atom Matter/antiMatter

The asymmetry between matter and antimatter 4 “The Standard Model” The fundamental building block of matter consists of: 6 quarks (u, d, c, s, t, b) 6 leptons (e,μ,τ,ν e,ν μ,ν τ ). These particles interact through four difference forces: electromagnetic strong forces weak forces gravity

The asymmetry between matter and antimatter 5 Where is the antimatter?

The asymmetry between matter and antimatter 6 EM EW Where is the antimatter? life 13.7 billion y 1 st stars 1 billion y 3000K 300,000 y H/He 300 s10 6 s10 11 s matter + antimatter < 10 11 sA atom nucleus hadrons

The asymmetry between matter and antimatter 7 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 violated almost

The asymmetry between matter and antimatter 8 P P C C Escher on CP violation… CP

The asymmetry between matter and antimatter 9 Weak interactions A main difference between electromagnetic and weak interactions is in the coupling constants g e and g ub e iγ,.. 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 gege g ub e iγ u b Weak interactions Electromagnetic interactions W+W+

The asymmetry between matter and antimatter 10 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

The asymmetry between matter and antimatter 11 CERN  4.4 km LEP e + e  ( GeV) LHC pp (14000 GeV) LHCb Atlas Alice CMS

The asymmetry between matter and antimatter 12 The LHCb detector The detector Results Simulation and Reconstruction

The asymmetry between matter and antimatter 13 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

The asymmetry between matter and antimatter 14 Additional slides!!!

The asymmetry between matter and antimatter 15 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

The asymmetry between matter and antimatter 16 The CKM-matrix and the γ- parameter The mixing of quarks in weak interactions is described by the CKM-matrix. The complex V xy entries of the matrix are the nine g w 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..

The asymmetry between matter and antimatter 17 Proposed project Improving the reconstruction program Developing the selection procedure of the B s ->D s K events Developing the fitting method in order to obtain the γ-parameter from the selected events