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When a particle decays, it often can decay in several ways. The likelihood of it decaying to a particular mode is known as its branching ratio for that decay mode.
Industry:Physics
In particle collisions, this is the energy that can go into making new particles. For a collider experiment where two beams of equal energy collide head-on, this is simply the sum of the energy of the two beams. In fixed target experiments, in which a beam of particles strikes a stationary target, the center-of-mass energy is significantly less than the sum of the energies of the two colliding particles.
Industry:Physics
Any particle that contains the exotic charmed (c) quark is known as a charmed particle.
Industry:Physics
A property of quarks and gluons. Gluons can exchange color between quarks and other gluons. This process is the origin of the strong force. It has nothing to do with the color perceived by the human eye.
Industry:Physics
Any of the particles from outer space that are continuously colliding with the Earth's atmosphere. They are mostly protons, with some nuclei, electrons, and photons. Their interactions with the atmosphere produce a variety of particles, including pions, muons, and neutrinos.
Industry:Physics
a measure of the likelihood of a given process occurring at an accelerator. The idea is that two objects with a larger cross-sectional area are more likely to hit one another. So, larger cross-sections mean that a process is more likely to occur. Cross-sections are measured in barns, 10<sup>-28</sup> m<sup>2</sup>. A barn is an extremely large cross-section in particle physics. Many interesting cross-sections are measured in pb (picobarns), which are equal to 10-12 barns.
Industry:Physics
A poorly understood (and non-luminous) substance that exerts a pressure that tends to accelerate the expansion of the universe. This dark energy counteracts gravity's natural tendency to slow the expansion of the universe. It is particularly important to understand this substance, as it appears to make up the majority of our universe. Dark energy is also often referred to as the "cosmological constant". It is distinct from dark matter, which gravitates in the same way as ordinary matter, but is not luminous.
Industry:Physics
Astronomical measurements indicate that luminous matter, such as our sun, makes up only a small percentage of the total matter in the universe. The missing mass that makes up the remainder is known as dark matter.
Industry:Physics
Exotic particles produced at accelerators are often very short-lived, and can transform into lighter, less exotic products, such as electrons and photons. This process of transformation is known as decay.
Industry:Physics
