Dark photon

The dark photon , also known as hidden, heavy or para-photon or phaeton , is a hypothetical particle that is supposed to interact with dark matter as an exchange particle similar to the photon of electromagnetism . In a minimal scenario, this new force can be introduced by adding a new Abelian U (1) symmetry to the calibration group of the Standard Model of particle physics . The corresponding new spin- 1 gauge boson (i.e. the dark photon) can then couple very weakly to electrically charged particles through kinetic mixing with the ordinary photon and could thus be detected. However, other types of coupling than kinetic mixing are also possible.

background

Observations of gravitational effects, which cannot be explained by visible matter alone, imply the existence of matter that is not or only weakly coupled to the known natural forces. This dark matter dominates the matter density of the universe, but its constituents, if any, could not be detected either directly or indirectly. In view of the versatile interaction structure of the known particles of the Standard Model, which only form the subdominant component of the universe, it is obvious to think about a similar interactive behavior of particles in the dark sector. Dark photons could be part of these interactions between particles of dark matter and, through kinetic mixing with the photon of the Standard Model , bring a non-gravitational insight, expressed as a vector portal , into their existence.

Another motivation for the search for dark photons are some anomalies observed in astrophysics (e.g. in cosmic rays ) which could be related to the interaction of dark matter with a dark photon. Probably the most interesting effect of dark photons arises from the explanation of the discrepancy between the measured and the calculated anomalous magnetic moment of the muon. This discrepancy is usually viewed as a persistent indication of physics beyond the Standard Model and should generally be accounted for by new physics models. In addition to the effect on electromagnetism through kinetic mixing and possible interactions with dark matter, dark photons (if massive) can themselves play the role of a candidate for dark matter. This is theoretically possible through the so-called misalignment mechanism .

theory

The addition of a sector containing dark photons to the Lagrangian of the Standard Model can be done in a simple and minimal way by introducing a new field of a gauge group. The properties of the interaction between this new field, the potential new particle content (e.g. a Dirac fermion for dark matter) and the particles of the Standard Model are practically only possible through the exclusion criteria ( no-go theorems ) that already apply within the Standard Model. limited. Probably the most popular basic model contains a new broken symmetry and a kinetic mixture between the corresponding dark photon field and the field of the unbroken gauge group of the standard model, i.e. the gauge bosons of the weak hypercharge . The operator occurring in the Lagrangian is , where is the field strength tensor of the dark photon field and the field strength tensor of the boson of the weak hypercharge. This term is the only coupling term allowed by gauge symmetry. After the electroweak symmetry breaking and the diagonalization of the electroweak gauge bosons in the eigenbase of the mass, the Lagrangian can be written as ${\displaystyle U(1)}$ ${\displaystyle U(1)}$ ${\displaystyle A^{\prime }}$ ${\displaystyle U(1)_{Y}}$ ${\displaystyle F_{\mu \nu }^{\prime }B^{\mu \nu }}$ ${\displaystyle F_{\mu \nu }^{\prime }}$ ${\displaystyle B^{\mu \nu }}$

${\displaystyle {\mathcal {L}}\supset -{\frac {1}{4}}F^{\prime \mu \nu }F_{\mu \nu }^{\prime }+{\frac {1}{2}}m_{A^{\prime }}^{2}A^{\prime \mu }A_{\mu }^{\prime }+\epsilon eA^{\prime \mu }J_{\mu }^{EM}}$

are written, where the mass of the dark photon, which is generated by a refraction of the , the parameter that describes the strength of the kinetic mixture and denotes the electromagnetic current with the elementary charge. The basic parameters of this model are thus the mass of the dark photon and the strength of the kinetic mixing. Other models maintain the new symmetry, resulting in a massless dark photon that has a long-range interaction. However, a massless dark photon is experimentally difficult to distinguish from the photon of the Standard Model. The incorporation of new Dirac fermions as dark matter particles into this theory is straightforward and can be achieved by simply adding the Dirac terms to the Lagrangian. ${\displaystyle m_{A^{\prime }}}$ ${\displaystyle U(1)}$ ${\displaystyle \epsilon }$ ${\displaystyle J_{\mu }^{EM}}$ ${\displaystyle e}$ ${\displaystyle U(1)}$

See also

• Dark radiation
• Fifth force

Individual evidence

1. ↑ ^{a b} R. Essig, JA Jaros, W. Wester, P. Hansson Adrian, S. Andreas, T. Averett, O. Baker, B. Batell, M. Battaglieri: Dark Sectors and New, Light, Weakly-Coupled Particles . In: arXiv - hep-ph . October 31, 2013. arxiv : 1311.0029 .
2. ↑ ^{a b} Bob Holdom: Two U (1) 's and ϵ charge shifts . In: Physics Letters B . 166, No. 2, January 9, 1986, ISSN  0370-2693 , pp. 196-198. bibcode : 1986PhLB..166..196H . doi : 10.1016 / 0370-2693 (86) 91377-8 .
3. ↑ Peter Galison, Aneesh Manohar: Two Z's or not two Z's? . In: Physics Letters B . 136, No. 4, March 8, 1984, ISSN  0370-2693 , pp. 279-283. bibcode : 1984PhLB..136..279G . doi : 10.1016 / 0370-2693 (84) 91161-4 .
4. ↑ Maxim Pospelov, Adam Ritz: Astrophysical Signatures of Secluded Dark Matter . In: Physics Letters B . 671, No. 3, January 2009, pp. 391-397. arxiv : 0810.1502 . bibcode : 2009PhLB..671..391P . doi : 10.1016 / j.physletb.2008.12.012 .
5. ↑ Nima Arkani-Hamed, Douglas P. Finkbeiner, Tracy R. Slatyer, Neal Weiner: A Theory of Dark Matter . In: Physical Review D . 79, No. 1, January 27, 2009, ISSN  1550-7998 , p. 015014. arxiv : 0810.0713 . bibcode : 2009PhRvD..79a5014A . doi : 10.1103 / PhysRevD.79.015014 .
6. ↑ Maxim Pospelov: Secluded U (1) below the weak scale . In: Physical Review D . 80, No. 9, November 2, 2009, ISSN  1550-7998 , p. 095002. arxiv : 0811.1030 . bibcode : 2009PhRvD..80i5002P . doi : 10.1103 / PhysRevD.80.095002 .
7. ↑ Motoi Endo, Koichi Hamaguchi, Go Mishima: Constraints on Hidden Photon Models from Electron g-2 and Hydrogen Spectroscopy . In: Physical Review D . 86, No. 9, November 27, 2012, ISSN  1550-7998 , p. 095029. arxiv : 1209.2558 . bibcode : 2012PhRvD..86i5029E . doi : 10.1103 / PhysRevD.86.095029 .
8. ^ D. Giusti, V. Lubicz, G. Martinelli, F. Sanfilippo, S. Simula: Strange and charm HVP contributions to the muon ($ g - 2) $ including QED corrections with twisted-mass fermions . In: Journal of High Energy Physics . 2017, No. 10, October 2017, ISSN  1029-8479 , p. 157. arxiv : 1707.03019 . bibcode : 2017JHEP ... 10..157G . doi : 10.1007 / JHEP10 (2017) 157 .
9. ↑ Paola Arias, Davide Cadamuro, Mark Goodsell, Joerg Jaeckel, Javier Redondo, Andreas Ringwald: WISPy Cold Dark Matter . In: Journal of Cosmology and Astroparticle Physics . 2012, No. 6, June 8, 2012, ISSN  1475-7516 , p. 013. arxiv : 1201.5902 . bibcode : 2012JCAP ... 06..013A . doi : 10.1088 / 1475-7516 / 2012/06/013 .
10. ^ Lotty Ackerman, Matthew R. Buckley, Sean M. Carroll, Marc Kamionkowski: Dark Matter and Dark Radiation . In: Physical Review D . 79, No. 2, January 23, 2009, ISSN  1550-7998 , p. 023519. arxiv : 0810.5126 . bibcode : 2009PhRvD..79b3519A . doi : 10.1103 / PhysRevD.79.023519 .
11. ^ Robert Foot, Sunny Vagnozzi: Dissipative hidden sector dark matter . In: Physical Review D . 91, No. 2, 2014, p. 023512. arxiv : 1409.7174 . bibcode : 2015PhRvD..91b3512F . doi : 10.1103 / PhysRevD.91.023512 .
12. ↑ Philip Ilten, Yotam Soreq, Mike Williams, Wei Xue: Serendipity in dark photon searches . In: Journal of High Energy Physics . 2018, No. 6, January 15, 2018. arxiv : 1801.04847 . doi : 10.1007 / JHEP06 (2018) 004 .