B Flavour Tagging with Artificial Neural Networks for the CDF II Experiment
- Karlsruhe Inst. of Technology (Germany)
One of the central questions arising from human curiosity has always been what matter is ultimately made of, with the idea of some kind of elementary building-block dating back to the ancient greek philosophers. Scientific activities of multiple generations have contributed to the current best knowledge about this question, the Standard Model of particle physics. According to it, the world around us is composed of a small number of stable elementary particles: Electrons and two different kinds of quarks, called up and down quarks. Quarks are never observed as free particles, but only as bound states of a quark-antiquark pair (mesons) or of three quarks (baryons), summarized as hadrons. Protons and Neutrons, the constituents forming the nuclei of all chemical elements, are baryons made of up and down quarks. The electron and the electron neutrino - a nearly massless particle without electric charge - belong to a group called leptons. These two quarks and two leptons represent the first generation of elementary particles. There are two other generations of particles, which seem to have similar properties as the first generation except for higher masses, so there are six quarks and six leptons altogether. They were around in large amounts shortly after the beginning of the universe, but today they are only produced in high energetic particle collisions. Properties of particles are described by quantum numbers, for example charge or spin. For every type of particle, a corresponding antiparticle exists with the sign of all charges swapped, but similar properties otherwise. The Standard Model is a very successful theory, describing the properties of all known particles and the interactions between them. Many of its aspects have been tested in various experiments at very high precision. Although none of these experimental tests has shown a significant deviation from the corresponding Standard Model prediction, the theory can not be complete yet: Cosmological aspects like gravity, dark matter and dark energy are not described, and open questions remain in the sector of neutrino masses and neutrino oscillations. Also no answer has been given to the question of matter-antimatter asymmetry observed in the contemporary universe. Assuming that the Big Bang created equal amounts of matter and antimatter, there must be effects where nature treats matter and antimatter somehow different. This can happen through a mechanism called CP violation, which has been observed within the Standard Model, but not in the necessary order of magnitude. For all these reasons, the search for New Physics - theories beyond the Standard Model - is one of the main objectives of modern particle physics. In this global effort, flavour physics is the field of transitions between the different types of quarks, called quark flavours, wherein the examination of B meson oscillations and the search for CP violation in B{sub s}{sup 0} meson decays set the stage for the work presented in this thesis.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 973214
- Report Number(s):
- FERMILAB-THESIS-2010-03; TRN: US1001711
- Country of Publication:
- United States
- Language:
- English
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Topics in Theoretical Physics
Related Subjects
AGE ESTIMATION
ANTIMATTER
B MESONS
BOUND STATE
ELECTRIC CHARGES
ELECTRON NEUTRINOS
ELEMENTARY PARTICLES
FERMILAB COLLIDER DETECTOR
LEPTONS
MASSLESS PARTICLES
NEURAL NETWORKS
NEUTRINO OSCILLATION
NONLUMINOUS MATTER
PHYSICS
QUANTUM NUMBERS
QUARKS
STANDARD MODEL
Experiment-HEP