BSM

Beyond the Standard Model (BSM) is a collective term for theories that extend, modify, or replace the Standard Model of particle physics to address phenomena that the Standard Model cannot explain. While the Standard Model describes fundamental particles and their interactions with remarkable success, it leaves unanswered questions such as the nature of dark matter, the origin of neutrino masses and mixings, the matter–antimatter asymmetry of the universe, and the hierarchy of energy scales.

BSM research encompasses a wide range of ideas, from new particles to new forces and principles. It often aims to be compatible with known experimental constraints while predicting testable signatures. The field includes both concrete model-building and more general phenomenological frameworks used to interpret data and guide experiments.

Common approaches include supersymmetry, extra spatial dimensions, extended Higgs sectors such as two-Higgs-doublet models, composite Higgs theories and technicolor, grand unified theories, and mechanisms invoking sterile neutrinos or dark sectors connected to the Standard Model through portal interactions (Higgs portal, vector portal, neutrino portal). These ideas seek to address unresolved issues and provide candidates for observable phenomena such as dark matter, new resonances, and deviations from Standard Model predictions.

Experimental efforts to probe BSM physics span high-energy collider experiments, precision measurements, neutrino experiments, and astrophysical and cosmological observations. Although no conclusive discovery has yet been made, searches at the Large Hadron Collider and in dark-matter detectors have constrained many models. The Standard Model Effective Field Theory (SMEFT) offers a model-independent framework to describe potential deviations from Standard Model predictions.

BSM physics sits at the interface of particle physics and cosmology, guiding theoretical development and experimental strategy as researchers seek a more complete understanding of fundamental interactions.