College Physics for AP® Courses

# Glossary

baryon number
a conserved physical quantity that is zero for mesons and leptons and $±1±1 size 12{ +- 1} {}$ for baryons and antibaryons, respectively
baryons
hadrons that always decay to another baryon
boson
particle with zero or an integer value of intrinsic spin
bottom
a quark flavor
charm
a quark flavor, which is the counterpart of the strange quark
colliding beams
head-on collisions between particles moving in opposite directions
color
a quark flavor
conservation of total baryon number
a general rule based on the observation that the total number of nucleons was always conserved in nuclear reactions and decays
conservation of total electron family number
a general rule stating that the total electron family number stays the same through an interaction
conservation of total muon family number
a general rule stating that the total muon family number stays the same through an interaction
cyclotron
accelerator that uses fixed-frequency alternating electric fields and fixed magnets to accelerate particles in a circular spiral path
down
the second-lightest of all quarks
electron family number
the number $±1±1 size 12{ +- 1} {}$ that is assigned to all members of the electron family, or the number 0 that is assigned to all particles not in the electron family
electroweak theory
theory showing connections between EM and weak forces
fermion
particle with a half-integer value of intrinsic spin
Feynman diagram
a graph of time versus position that describes the exchange of virtual particles between subatomic particles
flavors
quark type
fundamental particle
particle with no substructure
gauge boson
particle that carries one of the four forces
gluons
exchange particles, analogous to the exchange of photons that gives rise to the electromagnetic force between two charged particles
gluons
eight proposed particles which carry the strong force
grand unified theory
theory that shows unification of the strong and electroweak forces
particles that feel the strong nuclear force
Higgs boson
a massive particle that, if observed, would give validity to the theory that carrier particles are identical under certain circumstances
leptons
particles that do not feel the strong nuclear force
linear accelerator
accelerator that accelerates particles in a straight line
meson
particle whose mass is intermediate between the electron and nucleon masses
meson
hadrons that can decay to leptons and leave no hadrons
muon family number
the number $±1±1 size 12{ +- 1} {}$ that is assigned to all members of the muon family, or the number 0 that is assigned to all particles not in the muon family
particle physics
the study of and the quest for those truly fundamental particles having no substructure
pion
particle exchanged between nucleons, transmitting the force between them
quantum chromodynamics
quark theory including color
quantum chromodynamics
the governing theory of connecting quantum number color to gluons
quantum electrodynamics
the theory of electromagnetism on the particle scale
quark
an elementary particle and a fundamental constituent of matter
standard model
combination of quantum chromodynamics and electroweak theory
strange
the third lightest of all quarks
strangeness
a physical quantity assigned to various particles based on decay systematics
superstring theory
a theory of everything based on vibrating strings some $10−35m10−35m$ in length
synchrotron
a version of a cyclotron in which the frequency of the alternating voltage and the magnetic field strength are increased as the beam particles are accelerated
radiation caused by a magnetic field accelerating a charged particle perpendicular to its velocity
tau family number
the number $±1±1 size 12{ +- 1} {}$ that is assigned to all members of the tau family, or the number 0 that is assigned to all particles not in the tau family
theory of quark confinement
explains how quarks can exist and yet never be isolated or directly observed
top
a quark flavor
up
the lightest of all quarks
Van de Graaff
early accelerator: simple, large-scale version of the electron gun
virtual particles
particles which cannot be directly observed but their effects can be directly observed