Proton decay

The proton decay describes the hypothetical decay of a free proton in other elementary particles.

The proton decay is of some variants of the Grand Unified Theory ( GUT) predicted particle physics. Where it is assumed that a free proton is not stable, but only has a very high half-life. In contrast, protons are stable in the standard model, since the baryon number is conserved. Currently there are no experimental observations that support the hypothesis of proton decay.

There are numerous types of disintegration of a proton conceivable one possible example is mediated by a hypothetical X - boson decay in a positron e and a neutral Pion π0, the ( γ photons) then in a known way to radiation decays:

(B - L ) Since the positron is a antilepton, in this case the difference between baryon and lepton number is preserved. This is a prediction of most variants of GUT.

Quark model

In a simplified view (without the virtual quarks in p and π0 ) can be thought of as the decay of a proton:

The proton consists UUD from the quark constituents, the neutral pion is a quantum mechanical mixed state of dd and uu. The decay of the proton to the two components of the pion is now under the GUT via an intermediate hypothetical X and Y boson as:

With the ' uninvolved ' down - quark results:

And for the other component of π0:

With the ' uninvolved ' Up quark results:

Research

Despite an intensive search, no decay of a proton has been observed to date. It is predicted a half-life from 1031 to 1036 years of the theories.

Experiments Super - Kamiokande detector in Japan suggest a lower bound of the half-life of at least 1035 years. The observation of neutrino oscillation is an indication that a proton decay would in principle observable.

How Rubakow 1981 discovered also magnetic monopoles by catalysis may be able to contribute to proton decay. Such magnetic monopoles have ( they predictive theories, according to ) have a large mass; they have not been established.

A decay according to the same mechanism is also predicted for neutrons that are bound in the nucleus ( Free neutrons have an average life of about 885 seconds ).