particle physics
Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...
, a nonoblique correction, also called a direct correction, refers to a radiative correction of type
+ → +
in the
electroweak
In particle physics, the electroweak interaction or electroweak force is the unified description of two of the four known fundamental interactions of nature: electromagnetism and the weak interaction. Although these two forces appear very differe ...
sector of the Standard Model. These corrections are being studied at the CERNLEP collider. Together with the
oblique correction In particle physics, an oblique correction refers to a particular type of radiative correction to the electroweak sector of the Standard Model. Oblique corrections are defined in four- fermion scattering processes, ( + → &nbs ...
There are three classes of radiative corrections to these processes:
*
vacuum polarization
In quantum field theory, and specifically quantum electrodynamics, vacuum polarization describes a process in which a background electromagnetic field produces virtual electron–positron pairs that change the distribution of charges and curr ...
corrections,
* vertex corrections, and
* box corrections.
The vertex and box corrections, which depend on the identity of the initial and final state fermions, are referred to as the non-oblique corrections. The vacuum polarization corrections are referred to as
oblique correction In particle physics, an oblique correction refers to a particular type of radiative correction to the electroweak sector of the Standard Model. Oblique corrections are defined in four- fermion scattering processes, ( + → &nbs ...
s, since they only affect the mixing and propagation of the gauge bosons and they do not depend on which type of fermions appear in the initial or final states.
Examples
An example of a vertex correction is the nonuniversality (flavor dependence) of the couplings of the quarks and leptons to the charged and neutral weak currents. Another example is the
anomalous magnetic dipole moment
In quantum electrodynamics, the anomalous magnetic moment of a particle is a contribution of effects of quantum mechanics, expressed by Feynman diagrams with loops, to the magnetic moment of that particle. (The ''magnetic moment'', also called '' ...
.
In order to affect the nonoblique corrections, particles must couple directly to the external fermions. Such couplings are expected to be suppressed in most cases, with one exception being the vertex.