Graviphoton

In theoretical physics and quantum physics, a graviphoton or gravivector is a hypothetical particle which emerges as an excitation of the metric tensor (i.e. gravitational field) in spacetime dimensions higher than four, as described in Kaluza–Klein theory. However, its crucial physical properties are analogous to a (massive) photon: it induces a "vector force", sometimes dubbed a "fifth force". The electromagnetic potential <math>A_\mu</math> emerges from an extra component of the metric tensor <math>g_{\mu 5}</math>, where the figure 5 labels an additional, fifth dimension.<ref name="maa" />

In gravity theories with extended supersymmetry (extended supergravities), a graviphoton is normally a superpartner of the graviton that behaves like a photon, and is prone to couple with gravitational strength, as was appreciated in the late 1970s.<ref name="zac" /> Unlike the graviton, it may provide a repulsive (as well as an attractive) force, and thus, in some technical sense, a type of anti-gravity. Under special circumstances, in several natural models, often descending from five-dimensional theories mentioned, it may actually cancel the gravitational attraction in the static limit.<ref name="zac" /> Joël Scherk investigated semirealistic aspects of this phenomenon,<ref name="sch" /> stimulating searches<ref name="poll" /><ref>Fabbrichesi, M.; Roland, K. (1992). "Strong anti-gravity". Nuclear Physics B. 388 (2): 539–569. arXiv:hep-th/9205033. Bibcode:1992NuPhB.388..539F. doi:10.1016/0550-3213(92)90626-M. S2CID 1738568.</ref> for physical manifestations of this mechanism.

See also

• Graviscalar (a.k.a. radion)
• Supergravity