Dark photon

Beyond the Standard Model
Simulated Large Hadron Collider CMS particle detector data depicting a Higgs boson produced by colliding protons decaying into hadron jets and electrons
Standard Model
Evidence Hierarchy problem Dark matter Cosmological constant problem Strong CP problem Neutrino oscillation
Theories Technicolor Kaluza–Klein theory Grand Unified Theory Theory of everything String theory Causal fermion systems Superfluid vacuum theory
Supersymmetry MSSM Superstring theory Supergravity
Quantum gravity String theory Loop quantum gravity Causal dynamical triangulation Causal fermion systems Causal sets Canonical quantum gravity Superfluid vacuum theory
Experiments ANNIE Gran Sasso INO LHC SNO Super-K Tevatron NOνA

The dark photon is a hypothetical elementary particle, proposed as an electromagnetic force carrier for dark matter.^[1] Dark photons would theoretically be detectable via their mixing with ordinary photons, and subsequent effect on the interactions of known particles.^[1]

Dark photons were proposed in 2008 by Lotty Ackerman, Matthew R. Buckley, Sean M. Carroll, and Marc Kamionkowski as the force carrier of a new long-range U(1) gauge field, "dark electromagnetism", acting on dark matter.^[2] Like the ordinary photon, dark photons would be massless.^[2]

Dark photons were suggested to be a possible cause of the so-called 'g–2 anomaly' obtained by experiment E821 at Brookhaven National Laboratory,^[3] which appears to be three to four standard deviations above the Standard-Model values of Hagawara et al.^[4] and Davier et al.^[5] However, dark photons were largely ruled out as a cause of the anomaly by several experiments, including the PHENIX detector at the Relativistic Heavy Ion Collider at Brookhaven.^[1] A new experiment at Fermilab, the Muon g-2 experiment, expects to produce a precision four times better than the Brookhaven experiment.^[6]

More generally, a dark photon is any spin-1 boson associated with a new U(1) gauge field. That is, any new force of nature that arises in a theoretical extension of the Standard Model and generally behaves like electromagnetism. Unlike ordinary photons, these models often feature a dark photon that is unstable or possesses non-zero mass, rapidly decaying into other particles such as electron-positron pairs. They may also interact directly with the known particles, like electrons or muons, if said particles are charged under the new force.

See also

• Dark radiation
• Fifth force
• Photino

References

Dark matter
Forms of dark matter	Baryonic dark matter Cold dark matter Hot dark matter Light dark matter Mixed dark matter Warm dark matter Self-interacting dark matter Scalar field dark matter
Hypothetical particles	Axino Axion Dark photon Holeum LSP Minicharged particle Neutralino Sterile neutrino SIMP WIMP
Theories and objects	Cuspy halo problem Dark fluid Dark galaxy Dark matter halo Dark radiation Dark star Dwarf galaxy problem ELKO field Halo mass function Massive compact halo object Mirror matter Navarro–Frenk–White profile Scalar field dark matter
Search experiments	Direct detection ANAIS ArDM ADMX CDEX CDMS CoGeNT COUPP CRESST DAMA/LIBRA DAMA/NaI DarkSide DEAP DMTPC DRIFT EDELWEISS EURECA KIMS LUX LZ PandaX PICO SIMPLE UKDMC WARP XENON ZEPLIN-III Indirect detection AMS-02 ATIC CALET CAST DAMPE IceCube MOA OGLE PAMELA Other projects MultiDark PVLAS SNOLAB
Potential dark galaxies	HE0450-2958 HVC 127-41-330 Smith's Cloud VIRGOHI21
Related	Antimatter Dark energy Exotic matter Galaxy formation and evolution Illustris project