HEPTopicCompiled by AI, not yet reviewed by an editor

Grand unification and baryon number violation

The strong, weak and electromagnetic forces may be parts of a single force at very high energy. If so, protons should decay, very slowly.

Why it matters

Proton decay is the most direct test of unification at energies near $10^{16}\,\mathrm{GeV}$, far beyond any collider.

Review

P. Nath, P. Fileviez Perez, Proton stability in grand unified theories, in strings and in branes, Physics Reports, 2007. https://arxiv.org/abs/hep-ph/0601023 reference checked

Editors' decisions

Accept of version 2, Grand unification and baryon number violation, on 2026-10-15. Decision record

Timestamp record

Signed record: 4ab26fd00d33…
Public log: Entry 243, in checkpoint 2,123
In the log by: Block 969,698, 2026-10-03

This text was in the PubPhys log by that date. The date says nothing about when the problem was first posed.

Download record (.json) What a record shows

4 problems

Do the SM gauge forces unify into a single group?

Open

The strengths of the three forces change with energy and nearly meet near $10^{16}\, \mathrm{GeV}$. Whether they truly become one force is unknown.

Do neutrons oscillate into antineutrons?

Open

Some theories allow a neutron to turn into its own antiparticle, changing baryon number by two. This would not show up in proton decay searches.

Does the proton decay to an antineutrino and a kaon?

Open

Supersymmetric unified theories favor a different decay of the proton, into an antineutrino and a charged kaon. Detecting the kaon needs detectors with good tracking.

Is the proton lifetime to $e+ \pi0$ below $10^{35}\,\mathrm{years}$?

Open

Grand unified theories predict a proton can decay into a positron and a neutral pion. Huge water detectors watch for this rare event.