In
quantum field theory
In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines Field theory (physics), field theory and the principle of relativity with ideas behind quantum mechanics. QFT is used in particle physics to construct phy ...
, specifically the theory of
renormalization
Renormalization is a collection of techniques in quantum field theory, statistical field theory, and the theory of self-similar geometric structures, that is used to treat infinities arising in calculated quantities by altering values of the ...
, the bare mass of an elementary particle is the limit of its mass as the scale of distance approaches zero or, equivalently, as the energy of a particle collision approaches infinity. It differs from the
invariant mass
The invariant mass, rest mass, intrinsic mass, proper mass, or in the case of bound systems simply mass, is the portion of the total mass of an object or system of objects that is independent of the overall motion of the system. More precisely, ...
as usually understood because the latter includes the 'clothing' of the particle by pairs of
virtual particles
A virtual particle is a theoretical transient particle that exhibits some of the characteristics of an ordinary particle, while having its existence limited by the uncertainty principle, which allows the virtual particles to spontaneously emer ...
that are temporarily created by the fields around the particle. In some versions of QFT, the bare mass of some particles may be plus or minus infinity. In the theory of the
electroweak interaction
In particle physics, the electroweak interaction or electroweak force is the unified description of two of the fundamental interactions of nature: electromagnetism (electromagnetic interaction) and the weak interaction. Although these two force ...
using the
Higgs boson
The Higgs boson, sometimes called the Higgs particle, is an elementary particle in the Standard Model of particle physics produced by the excited state, quantum excitation of the Higgs field,
one of the field (physics), fields in particl ...
, all particles have a bare mass of zero.
This allows us to write
, where
denotes the experimentally observable mass of the particle,
its bare mass, and
the increase in mass owing to the interaction of the particle with the medium or field.
See also
*
Pole mass
*
Relativistic Breit–Wigner distribution
*
Infraparticle
References
*
Mass
Quantum field theory
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