LECTURE 9 Chasing Relativistic Particles Not timed Instructor: Shih-Chieh Hsu

Announcement Final Report This Thursday 9:20am Each person has 7.5mins Remember the structure of the talk What Why Who When Where Results Discussion

The CMS Masterclass Successful teamwork last week

The CMS Masterclass Discussions the W+/W- ratio. the e/μ ratio. the mass of the Z and other particles with similar decays from the statistical combination in a mass plot. How are our masterclass results compared to actual Higgs discovery? Detector/Physics/Analysis

Elementary Particles

Interactions

Quantum Mechanics "quantum," which means "broken into increments or parcels,” is used to describe the physics of very small particles A few of the important quantum numbers of particles are: Electric charge. Quarks may have 2/3 or 1/3 electron charges, but they only form composite particles with integer electric charge. Color charge. A quark carries one of three color charges and a gluon carries one of eight color-anticolor charges. All other particles are color neutral. Flavor. Flavor distinguishes quarks (and leptons) from one another.

Spin Spin is a bizarre but important physical quantity. Large objects like planets or marbles may have angular momentum and a magnetic field because they spin. Since particles also to appear to have their own angular momentum and tiny magnetic moments, physicists called this particle property spin. This is a misleading term since particles are not actually "spinning." Spin is quantized to units of 0, 1/2, 1, 3/2 (times Planck's Constant, ) and so on.

Pauli Exclusion Principle no two particles in the same quantum state could exist in the same place at the same time. But it has been since discovered that a certain group of particles do not obey this principle. Particles that do obey the Pauli Exclusion Principle are called fermions, and those that do not are called bosons.

Fermions & Bosons Behavior

Fermions and Bosons: Explained The predicted graviton has a spin of 2.

A Lot To Remember We have answered the questions, "What is the world made of?" and "What holds it together?" The world is made of six quarks and six leptons. Everything we see is a conglomeration of quarks and leptons. There are four fundamental forces and there are force carrier particles associated with each force. We have also discussed how a particle's state (set of quantum numbers) may affect how it interacts with other particles. These are the essential aspects of the Standard Model. It is the most complete explanation of the fundamental particles and interactions to date.

Elementary Particles

Big Theory Chart

How to detect the Higgs Boson?

Detecting invisible

What are debris? http://pdg.lbl.gov Life time is longer enough to fly through the detector The tracker radius is about 1m The lifetime of particle is longer than 3×10-9s http://pdg.lbl.gov

Particles and Detectors

How to measure charged & momentum? What happen for a neutral particle passing through magnet?

Particles and Detectors

* location of magnet depends on specific detector design Generic Design Cylinders wrapped around the beam pipe From inner to outer . . . Tracking Electromagnetic calorimeter Hadronic calorimeter Magnet* Muon chamber * location of magnet depends on specific detector design

Particle Detection

Quiz1 e-, e+ muon+, muon-

Quiz2 quark-antiquark quark-antiquark+ gluon (?)