In experimental particle physics, missing energy refers to energy which is not detected in a particle detector, but is expected due to the laws of conservation of energy and conservation of momentum. For example, if an electron and a positron collide head-on at equal speeds in the lab frame, any net momentum of outgoing particles indicates a missing energy. Missing energy is generally attributed to particles which escape the detector without being detected. Although, apparent missing energy may also be caused by mismeasurement within a field that is also attributed to executive functions of physics on the energy/momentum of detected particles.
In hadron colliders, the initial momentum of the colliding partons along the beam axis is not known (because the energy of each hadron is split, and constantly exchanged, between its constituents), so the amount of total missing energy cannot be determined. However, the initial energy in particles travelling transverse to the beam axis is zero, so any net momentum in the transverse direction indicates missing transverse energy.
Missing energy is commonly used to infer the presence of non-detectable particles such as the standard model neutrino and is expected to be a signature of many new physics events.
Famous quotes containing the words missing and/or energy:
“Teenage girls are extremists who see the world in black-and- white terms, missing shades of gray. Life is either marvelous or not worth living. School is either pure torment or is going fantastically. Other people are either great or horrible, and they themselves are wonderful or pathetic failures. One day a girl will refer to herself as “the goddess of social life” and the next day she’ll regret that she’s the “ultimate in nerdosity.””
—Mary Pipher (20th century)
“In the west, Apollo and Dionysus strive for victory. Apollo makes the boundary lines that are civilization but that lead to convention, constraint, oppression. Dionysus is energy unbound, mad, callous, destructive, wasteful. Apollo is law, history, tradition, the dignity and safety of custom and form. Dionysus is the new, exhilarating but rude, sweeping all away to begin again. Apollo is a tyrant, Dionysus is a vandal.”
—Camille Paglia (b. 1947)