Bjorken scaling

Bjorken scaling is the approximate independence of deep inelastic scattering structure functions from momentum transfer at fixed Bjorken x, when the transfer is large.

Deep inelastic scattering: A high-energy collision in which a lepton probes the internal structure of a hadron through an exchanged virtual particle. It is the process whose structure functions exhibit Bjorken scaling.
James Bjorken: An American theoretical physicist whose work predicted scaling behavior in deep inelastic scattering. He proposed the scaling prediction that bears his name.
Structure function: A function encoding the internal response of a target in a scattering process. Bjorken scaling is a claim about the momentum-transfer dependence of these functions.
Quark: A fundamental fermion that carries color charge and combines with other quarks or gluons in hadrons. The constituents inferred from scaling were identified with quarks.
Bjorken x: A dimensionless variable in deep inelastic scattering that, in the parton model, represents a struck parton's momentum fraction. Scaling means structure functions depend mainly on this variable rather than momentum transfer.
SLAC-MIT deep inelastic scattering experiments: A series of experiments at the Stanford Linear Accelerator Center that used electron scattering to probe nucleon structure. Their data revealed approximate scaling at large momentum transfer.
Four-momentum transfer: The difference between the incoming and outgoing four-momenta in a particle interaction. Its squared magnitude sets the probe's momentum-transfer scale.
Proton structure: The distribution of quarks, gluons, and their interactions within a proton. Scaling measurements exposed the proton's pointlike constituents and their momentum distributions.
Parton model: A model treating high-energy hadron scattering as incoherent collisions with pointlike constituents called partons. Its pointlike constituents explain why the structure functions approach energy-independent forms.
Stanford Linear Accelerator Center: A United States national laboratory for particle physics research, located in California. Its accelerator enabled the electron-proton measurements that established scaling.

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