mirror matter

Modern physics deals with three basic types of spatial symmetry: reflection, rotation, and translation. The known elementary particles respect rotational symmetry and translational symmetry but some do not respect mirror reflection symmetry (also called P-symmetry or parity). Of the four fundamental interactions—electromagnetism, the strong interaction, the weak interaction, and gravity—only the weak interaction breaks parity.

Parity violation in weak interactions was first postulated by Tsung-Dao Lee and Chen-Ning Yang{{cite journal |last1=Lee |first1=T.D. |author1-link=Tsung Dao Lee |last2=Yang |first2=C.N. |author2-link=Chen Ning Yang |year=1956 |title=Question of parity conservation in weak interactions |journal=Physical Review |volume=104 |issue = 1 |pages=254–258 |bibcode = 1956PhRv..104..254L |doi=10.1103/PhysRev.104.254 |doi-access=free }} {{erratum |bibcode=1957PhRv..106.1371L |doi=10.1103/PhysRev.106.1371 |checked=yes}} in 1956 as a solution to the Kaon#Parity violation. In consultation with the experimental physicist Chien-Shiung Wu a number of possibilities were proposed to test whether the weak interaction was in fact invariant under parity. One of the group's suggestions involved monitoring the decay of Cobalt-60,

$\{\}^\{60\}\_\{27\}\backslash text\{Co\}\; \backslash rightarrow\; \{\}^\{60\}\_\{28\}\backslash text\{Ni\}\; +\; e^-\; +\; \backslash bar\{\backslash nu\}\_e\; +\; 2\{\backslash gamma\}$

However, parity symmetry can be restored as a fundamental symmetry of nature if the particle content is enlarged so that every particle has a mirror partner. The theory in its modern form was described in 1991,{{cite journal |last1 = Foot |first1 = R. |last2 = Lew |first2 = H. |last3 = Volkas |first3 = R.R. |year = 1991 |title = A model with fundamental improper spacetime symmetries |journal = Physics Letters B |volume = 272 |issue = 1–2 |pages = 67–70 |bibcode = 1991PhLB..272...67F |doi = 10.1016/0370-2693(91)91013-L }} although the basic idea dates back further.{{cite journal |first1=I. |last1=Kobzarev |first2=L. |last2=Okun |first3=I. |last3=Pomeranchuk |title=On the possibility of observing mirror particles |journal=Soviet Journal of Nuclear Physics |volume=3 |page=837 |year=1966}}{{cite journal |last = Pavšič |first = Matej |year = 1974 |title = External inversion, internal inversion, and reflection invariance |journal = International Journal of Theoretical Physics |volume = 9 |issue = 4 |pages = 229–244 |arxiv = hep-ph/0105344 |doi = 10.1007/BF01810695 |bibcode = 1974IJTP....9..229P |s2cid = 15736872 }} Mirror particles interact amongst themselves in the same way as ordinary particles, except where ordinary particles have left-handed interactions, mirror particles have right-handed interactions. In this way, it turns out that mirror reflection symmetry can exist as an exact symmetry of nature, provided that a "mirror" particle exists for every ordinary particle. Parity can also be spontaneously broken depending on the Higgs potential.{{cite journal |last1 = Berezhiani |first1 = Zurab G. |last2 = Mohapatra |first2 = Rabindra N. |year = 1995 |title = Reconciling present neutrino puzzles: Sterile neutrinos as mirror neutrinos |journal = Physical Review D |volume = 52 |issue = 11 |pages = 6607–6611 |arxiv = hep-ph/9505385 |doi = 10.1103/PhysRevD.52.6607 |bibcode = 1995PhRvD..52.6607B |pmid = 10019200 |s2cid = 11306189 }}{{cite journal |last1 = Foot |first1 = Robert |last2 = Lew |first2 = Henry |last3 = Volkas |first3 = Raymond Robert |year = 2000 |title = Unbroken versus broken mirror world: A tale of two vacua |journal = Journal of High Energy Physics |volume = 2000 |issue = 7 |page = 032 |bibcode = 2000JHEP...07..032F |arxiv = hep-ph/0006027 |doi = 10.1088/1126-6708/2000/07/032 |s2cid = 11013856 }} While in the case of unbroken parity symmetry the masses of particles are the same as their mirror partners, in case of broken parity symmetry the mirror partners are lighter or heavier.

Mirror matter, if it exists, would interact weakly in strength with ordinary matter. This is because the forces between mirror particles are mediated by mirror bosons. With the exception of the graviton, none of the known bosons can be identical to their mirror partners. The only way mirror matter can interact with ordinary matter via forces other than gravity is via kinetic mixing of mirror bosons with ordinary bosons. These interactions can only be very weak. Mirror particles have therefore been suggested as candidates for the inferred dark matter in the universe.{{cite journal | last1 = Blinnikov |first1=S.I. |last2=Khlopov |first2=M.Yu. | year = 1982 | title = On possible effects of 'mirror' particles | journal = Soviet Journal of Nuclear Physics | volume = 36 | page = 472 }}{{cite journal | last1 = Blinnikov |first1=S.I. |last2=Khlopov |first2=M. Yu. | year = 1983 | title = Possible astronomical effects of mirror particles | journal = Sov. Astron. | volume = 27 | pages = 371–375 | bibcode = 1983SvA....27..371B }}{{cite journal | last1 = Kolb | first1 = E.W. | last2 = Seckel | first2 = M. | last3 = Turner | first3 = M.S. | year = 1985 | title = The shadow world of superstring theories | journal = Nature | volume = 314 | issue = 6010 | pages = 415–419 | doi = 10.1038/314415a0 | bibcode = 1985Natur.314..415K | s2cid = 4353658 }}{{cite journal |first1=M.Yu. |last1=Khlopov |first2=G. M. |last2=Beskin |first3=N.E. |last3=Bochkarev |first4=L.A. |last4=Pushtilnik |first5=S. A. |last5=Pushtilnik |title=Observational physics of mirror world |journal=Astron. Zh. Akad. Nauk SSSR |volume=68 |pages=42–57 |year=1991 |url=http://lss.fnal.gov/archive/1989/pub/Pub-89-193-A.pdf |archive-url=https://web.archive.org/web/20110605225123/http://lss.fnal.gov/archive/1989/pub/Pub-89-193-A.pdf |archive-date=2011-06-05 |url-status=live}}{{cite journal | last = Hodges | first = H.M. | year = 1993 | title = Mirror baryons as the dark matter | journal = Physical Review D | volume = 47 | issue = 2 | pages = 456–459 | bibcode = 1993PhRvD..47..456H | doi = 10.1103/PhysRevD.47.456 | pmid = 10015599 }}

In another context, mirror matter has been proposed to give rise to an effective Higgs mechanism responsible for the electroweak symmetry breaking. In such a scenario, mirror fermions acquire masses on the order of 1 TeV since they interact with an additional gauge interaction not only becoming strong around the characteristic energy scale of the electroweak interactions but also being theoretically unified with Standard Model interactions under a larger gauge symmetry near the Planck energy scale. In order to emphasize the distinction of this model from the ones above, these mirror particles are usually called katoptrons{{cite journal | last = Triantaphyllou | first = G. | year = 2001 | title = Mass generation and the dynamical role of the Katoptron group | journal = Modern Physics Letters A | volume = 16 | issue = 2 | pages = 53–62 | doi = 10.1142/S0217732301002274 | bibcode = 2001MPLA...16...53T | arxiv = hep-ph/0010147 | s2cid = 15689479 }}{{cite journal | last1 = Triantaphyllou | first1 = G. | last2 = Zoupanos | first2 = G. | year = 2000 | title = Strongly interacting fermions from a higher dimensional unified gauge theory | journal = Physics Letters B | volume = 489 | issue = 3–4 | pages = 420–426 | doi = 10.1016/S0370-2693(00)00942-4 | citeseerx = 10.1.1.347.9373 | bibcode = 2000PhLB..489..420T | arxiv = hep-ph/0006262 | s2cid = 17505679 }}{{cite journal |last=Triantaphyllou |first=G. |year=2016 |title=Mirror mesons at the Large Hadron Collider (LHC) |journal=Electronic Journal of Theoretical Physics |volume=13 |issue=35 |pages=115–144 |url=http://arxiv.org/abs/1609.03404 |access-date=2024-02-07 |arxiv=1609.03404 }} within the context of the Katoptron model and they are expected to decay to Standard Model particles shortly after their creation.

Mirror matter could have been diluted to unobservably low densities during the inflation epoch. Sheldon Glashow has shown that if, at some high energy scale, particles exist which interact strongly with both ordinary and mirror particles, radiative corrections will lead to a mixing between photons and mirror photons.{{Cite journal |doi = 10.1016/0370-2693(86)90540-X|title = Positronium versus the mirror universe|journal = Physics Letters B|volume = 167|issue = 1|pages = 35–36|year = 1986|last1 = Glashow|first1 = S.L.|bibcode = 1986PhLB..167...35G}} This mixing has the effect of giving mirror electric charges a very small ordinary electric charge. Another effect of photon–mirror photon mixing is that it induces oscillations between positronium and mirror positronium. Positronium could then turn into mirror positronium and then decay into mirror photons.

The mixing between photons and mirror photons could be present in tree-level Feynman diagrams or arise as a consequence of quantum corrections due to the presence of particles that carry both ordinary and mirror charges. In the latter case, the quantum corrections have to vanish at the one and two loop-level Feynman diagrams, otherwise the predicted value of the kinetic mixing parameter would be larger than experimentally allowed.

An experiment to measure this effect was being planned in November 2003.{{Cite journal |arxiv = hep-ex/0311031|doi = 10.1142/S0217751X04020105|title = An Apparatus to Search for Mirror Dark Matter|journal = International Journal of Modern Physics A|volume = 19|issue = 23|pages = 3833–3847|year = 2004|last1 = Gninenko|first1 = S. N.|bibcode = 2004IJMPA..19.3833G|s2cid = 17721669}}

If mirror matter does exist in large abundances in the universe and if it interacts with ordinary matter via photon—mirror photon mixing, then this could be detected in dark matter direct detection experiments such as DAMA/NaI and its successor DAMA/LIBRA. In fact, it is one of the few dark matter candidates which can explain the positive DAMA/NaI dark matter signal whilst still being consistent with the null results of other dark matter experiments.{{Cite journal |arxiv = hep-ph/0308254|doi = 10.1103/PhysRevD.69.036001|title = Implications of the DAMA and CRESST experiments for mirror matter-type dark matter|journal = Physical Review D|volume = 69|issue = 3|pages = 036001|year = 2004|last1 = Foot|first1 = R.|bibcode = 2004PhRvD..69c6001F|s2cid = 14580403}}{{Cite journal |arxiv = astro-ph/0405362|doi = 10.1142/S0217732304015051|title = Reconciling the Positive Dama Annual Modulation Signal with the Negative Results of the CDSM II Experiment|journal = Modern Physics Letters A|volume = 19|issue = 24|pages = 1841–1846|year = 2004|last1 = Foot|first1 = R.|bibcode = 2004MPLA...19.1841F|s2cid = 18243354}}

Mirror matter may also be detected in electromagnetic field penetration experiments{{Cite journal |arxiv = astro-ph/0605369|doi = 10.1103/PhysRevD.74.043532|title = Detecting dark matter in electromagnetic field penetration experiments|journal = Physical Review D|volume = 74|issue = 4|pages = 043532|year = 2006|last1 = Mitra|first1 = Saibal|bibcode = 2006PhRvD..74d3532M|s2cid = 119497509}} and there would also be consequences for planetary science{{Cite journal |arxiv = astro-ph/0211067|doi = 10.1016/S0927-6505(03)00119-1|title = Mirror matter in the solar system: New evidence for mirror matter from Eros|journal = Astroparticle Physics|volume = 19|issue = 6|pages = 739–753|year = 2003|last1 = Foot|first1 = R.|last2 = Mitra|first2 = S.|bibcode = 2003APh....19..739F|s2cid = 17578958}}{{Cite journal |last1=Foot |first1=R. |last2=Silagadze |first2=Z. K. |year=2001 |title=Do mirror planets exist in our solar system? |journal=Acta Physica Polonica B |volume=32 |issue=7 |pages=2271 |arxiv=astro-ph/0104251 |bibcode=2001AcPPB..32.2271F}} and astrophysics.{{Cite journal |arxiv = astro-ph/0205059|doi = 10.1142/S021773230200926X|title = Improved Limits on Photon Velocity Oscillations|journal = Modern Physics Letters A|volume = 17|issue = 38|pages = 2491–2496|year = 2002|last1 = De Angelis|first1 = Alessandro|last2 = Pain|first2 = Reynald|bibcode = 2002MPLA...17.2491D|s2cid = 3042840}}

Mirror matter could also be responsible for the GZK puzzle. Topological defects in the mirror sector could produce mirror neutrinos which can oscillate to ordinary neutrinos.{{Cite journal |arxiv = hep-ph/9908257|doi = 10.1103/PhysRevD.62.083512|title = Ultrahigh energy neutrinos from hidden-sector topological defects|journal = Physical Review D|volume = 62|issue = 8|pages = 083512|year = 2000|last1 = Berezinsky|first1 = V.|last2 = Vilenkin|first2 = A.|bibcode = 2000PhRvD..62h3512B|s2cid = 204936092}} Another possible way to evade the GZK bound is via neutron–mirror neutron oscillations.{{Cite journal |arxiv = hep-ph/0507031|doi = 10.1103/PhysRevLett.96.081801|pmid = 16606167|title = Neutron–Mirror-Neutron Oscillations: How Fast Might They Be?|journal = Physical Review Letters|volume = 96|issue = 8|pages = 081801|year = 2006|last1 = Berezhiani|first1 = Zurab|last2 = Bento|first2 = Luís|bibcode = 2006PhRvL..96h1801B|s2cid = 2171296}}{{Cite journal |arxiv = hep-ph/0602227|doi = 10.1016/j.physletb.2006.03.008|title = Fast neutron–mirror neutron oscillation and ultra high energy cosmic rays|journal = Physics Letters B|volume = 635|issue = 5–6|pages = 253–259|year = 2006|last1 = Berezhiani|first1 = Zurab|last2 = Bento|first2 = Luís|bibcode = 2006PhLB..635..253B|s2cid = 119481860}}{{Cite journal |arxiv = hep-ph/0508109|doi = 10.1016/j.physletb.2005.08.101|title = Some implications of neutron mirror neutron oscillation|journal = Physics Letters B|volume = 627|issue = 1–4|pages = 124–130|year = 2005|last1 = Mohapatra|first1 = R.N.|last2 = Nasri|first2 = S.|last3 = Nussinov|first3 = S.|s2cid = 119028382}}{{Cite journal |arxiv = nucl-ex/0601017|doi = 10.1016/j.physletb.2006.06.005|title = On the experimental search for neutron → mirror neutron oscillations|journal = Physics Letters B|volume = 639|issue = 3–4|pages = 214–217|year = 2006|last1 = Pokotilovski|first1 = Yu.N.|bibcode = 2006PhLB..639..214P|s2cid = 16896749}}

If mirror matter is present in the universe with sufficient abundance then its gravitational effects can be detected. Because mirror matter is analogous to ordinary matter, it is then to be expected that a fraction of the mirror matter exists in the form of mirror galaxies, mirror stars, mirror planets etc. These objects can be detected using gravitational microlensing.{{Cite journal |bibcode = 1999PhLB..462..302M|title = Mirror matter MACHOs|journal = Physics Letters B|volume = 462|issue = 3–4|pages = 302–309|last1 = Mohapatra|first1 = R. N.|last2 = Teplitz|first2 = Vigdor L.|year = 1999|arxiv = astro-ph/9902085|doi = 10.1016/S0370-2693(99)00789-3|s2cid = 119427850}} One would also expect that some fraction of stars have mirror objects as their companion. In such cases one should be able to detect periodic Doppler shifts in the spectrum of the star. There are some hints that such effects may already have been observed.{{Cite journal |arxiv = astro-ph/9902065|doi = 10.1016/S0370-2693(99)00230-0|title = Have mirror stars been observed?|journal = Physics Letters B|volume = 452|issue = 1–2|pages = 83–86|year = 1999|last1 = Foot|first1 = R.|bibcode = 1999PhLB..452...83F|s2cid = 11374130}}

Neutrons which are electrically neutral particles of ordinary matter could oscillate into its mirror partner, the mirror neutron.{{cite journal |last1=Berezhiani |first1=Zurab |last2=Bento |first2=Luis |date=2006-02-27 |title=Neutron - mirror neutron oscillations: How fast might they be? |arxiv=hep-ph/0507031 |journal=Physical Review Letters |volume=96 |issue=8 |page=081801 |doi=10.1103/PhysRevLett.96.081801 |pmid=16606167 |bibcode=2006PhRvL..96h1801B |s2cid=2171296 |issn=0031-9007}} Recent experiments looked for neutrons vanishing into the mirror world. Most experiments found no signal and hence gave limits on transition rates to the mirror state,{{Cite journal |last1=Ban |first1=G. |last2=Bodek |first2=K. |last3=Daum |first3=M. |last4=Henneck |first4=R. |last5=Heule |first5=S. |last6=Kasprzak |first6=M. |last7=Khomutov |first7=N. |last8=Kirch |first8=K. |last9=Kistryn |first9=S. |last10=Knecht |first10=A. |last11=Knowles |first11=P. |display-authors=6 |date=2007-10-19 |title=A direct experimental limit on neutron – mirror neutron oscillations |arxiv=0705.2336 |journal=Physical Review Letters |volume=99 |issue=16 |pages=161603 |doi=10.1103/PhysRevLett.99.161603 |pmid=17995237 |bibcode=2007PhRvL..99p1603B |s2cid=20503448 |issn=0031-9007}}{{cite journal |last1=Abel |first1=C. |last2=Ayres |first2=N.J. |last3=Ban |first3=G. |last4=Bison |first4=G. |last5=Bodek |first5=K. |last6=Bondar |first6=V. |last7=Chanel |first7=E. |last8=Chiu |first8=P.-J. |last9=Crawford |first9=C. |last10=Daum |first10=M. |last11=Dinani |first11=R.T. |display-authors=6 |date=January 2021 |title=A search for neutron to mirror-neutron oscillations |arxiv=2009.11046 |journal=Physics Letters B |volume=812 |pages=135993 |doi=10.1016/j.physletb.2020.135993|s2cid=228076358 }}{{Cite journal |last1=Serebrov |first1=A.P. |last2=Aleksandrov |first2=E.B. |last3=Dovator |first3=N.A. |last4=Dmitriev |first4=S.P. |last5=Fomin |first5=A.K. |last6=Geltenbort |first6=P. |last7=Kharitonov |first7=A.G. |last8=Krasnoschekova |first8=I.A. |last9=Lasakov |first9=M.S. |last10=Murashkin |first10=A.N. |last11=Shmelev |first11=G.E. |display-authors=6 |date=May 2008 |title=Experimental search for neutron – mirror neutron oscillations using storage of ultracold neutrons |arxiv=0706.3600 |journal=Physics Letters B |volume=663 |issue=3 |pages=181–185 |doi=10.1016/j.physletb.2008.04.014|bibcode=2008PhLB..663..181S |s2cid=119132581 }}{{Cite journal |last1=Altarev |first1=I. |last2=Baker |first2=C.A. |last3=Ban |first3=G. |last4=Bodek |first4=K. |last5=Daum |first5=M. |last6=Fierlinger |first6=P. |last7=Geltenbort |first7=P. |last8=Green |first8=K. |last9=van der Grinten |first9=M.G.D. |last10=Gutsmiedl |first10=E. |last11=Harris |first11=P.G. |display-authors=6 |date=2009-08-17 |title=Neutron to mirror-neutron oscillations in the presence of mirror magnetic fields |arxiv=0905.4208 |journal=Physical Review D |volume=80 |issue=3 |pages=032003 |doi=10.1103/PhysRevD.80.032003 |bibcode=2009PhRvD..80c2003A |s2cid=7423799 |issn=1550-7998}} one paper claimed signals.{{Cite journal |last1=Berezhiani |first1=Z. |last2=Biondi |first2=R. |last3=Geltenbort |first3=P. |last4=Krasnoshchekova |first4=I.A. |last5=Varlamov |first5=V.E. |last6=Vassiljev |first6=A.V. |last7=Zherebtsov |first7=O.M. |date=2018-09-01 |title=New experimental limits on neutron – mirror neutron oscillations in the presence of mirror magnetic field |url=https://epjc.epj.org/articles/epjc/abs/2018/09/10052_2018_Article_6189/10052_2018_Article_6189.html |journal=The European Physical Journal C |lang=en |volume=78 |issue=9 |pages=717 |doi=10.1140/epjc/s10052-018-6189-y |arxiv=1712.05761 |bibcode=2018EPJC...78..717B |s2cid=119250376 |issn=1434-6044}} Current research looks for signals where an applied magnetic field adjust the energy level of the neutron to the mirror world.{{cite journal |last1=Ayres |first1=N.J. |last2=Berezhiani |first2=Z. |last3=Biondi |first3=R. |last4=Bison |first4=G. |last5=Bodek |first5=K. |last6=Bondar |first6=V. |last7=Chiu |first7=P.-J. |last8=Daum |first8=M. |last9=Dinani |first9=R.T. |last10=Doorenbos |first10=C.B. |last11=Emmenegger |first11=S. |display-authors=6 |date=2021-10-31 |title=Improved search for neutron to mirror-neutron oscillations in the presence of mirror magnetic fields with a dedicated apparatus at the PSI UCN source |journal=Symmetry |volume=14 |issue=3 |page=503 |doi=10.3390/sym14030503 |arxiv=2111.02794 |bibcode=2022Symm...14..503A |doi-access=free }}{{cite journal |last1=Broussard |first1=L.J. |last2=Bailey |first2=K.M. |last3=Bailey |first3=W.B. |last4=Barrow |first4=J. L. |last5=Berry |first5=K. |last6=Blose |first6=A. |last7=Crawford |first7=C. |last8=Debeer-Schmitt |first8=L. |last9=Frost |first9=M. |last10=Galindo-Uribarri |first10=A. |last11=Gallmeier |first11=F.X. |display-authors=6 |year=2019 |title=New search for mirror neutron regeneration |url=https://www.epj-conferences.org/articles/epjconf/abs/2019/24/epjconf-ppns2019_07002/epjconf-ppns2019_07002.html |journal=EPJ Web of Conferences |lang=en |volume=219 |pages=07002 |doi=10.1051/epjconf/201921907002 |arxiv=1912.08264 |bibcode=2019EPJWC.21907002B |s2cid=209405136 |issn=2100-014X }} This energy difference can be interpreted due to a mirror magnetic field present in the mirror world or a mass difference of the neutron and its mirror partner.{{cite web |title=Dark matter search |website=PSI Center for Neutron and Muon Sciences (psi.ch) |series=Laboratory for Particle Physics |publisher=Paul Scherrer Institute |place=Villigen & Würenlingen, CH |url=https://www.psi.ch/en/ltp-ucn-physics/dark-matter-search }} Such a transition to the mirror world could also solve the neutron lifetime puzzle.{{cite journal |last=Berezhiani |first=Zurab |date=2019-06-10 |title=Neutron lifetime puzzle and neutron – mirror neutron oscillation |url=https://doi.org/10.1140/epjc/s10052-019-6995-x |journal=The European Physical Journal C |lang=en |volume=79 |issue=6 |pages=484 |doi=10.1140/epjc/s10052-019-6995-x |arxiv=1807.07906 |bibcode=2019EPJC...79..484B |s2cid=119232602 |issn=1434-6052}}

Experiments searching for mirror neutron oscillation are ongoing at the Paul Scherrer Institute's UCN source in Switzerland, Institut Laue-Langevin in France, and via the Spallation Neutron Source at the Oak Ridge National Laboratory in the U.S.{{cite press release |first=Dawn |last=Levy |date=26 July 2019 |title=Leah Broussard: Breaking the Standard Model to fix understanding of the Universe |via=neutrons.ornl.gov |publisher=Oak Ridge National Laboratory |place=Oak Ridge, TN |url=https://neutrons.ornl.gov/content/leah-broussard-breaking-standard-model-fix-understanding-universe }}

{{col div|colwidth=30em}}

• {{annotated link|Antimatter}}
• {{annotated link|Dark energy}}
• {{annotated link|Dark matter}}
• {{annotated link|Gravitational interaction of antimatter}}
• {{annotated link|Negative energy}}
• {{annotated link|Negative mass}}
• {{annotated link|Strange matter}}
• {{annotated link|QCD matter}}

{{colend}}

{{reflist|25em}}

{{refbegin|25em|small=yes}}

• {{cite web |editor=smitra |title=Mirror |type=bibliography |url=http://people.zeelandnet.nl/smitra/mirror.htm |via=zeelandnet.nl/smitra }} — A collection of scientific articles' abstracts and media links for various aspects of mirror matter theory.
• {{cite news |title=Mirror matter |series=h2g2 |publisher=British Broadcasting Corporation |url=https://www.bbc.co.uk/dna/h2g2/A1300429 |via=bbc.co.uk }}
• {{cite journal |first=R. |last=Foot | year=2004 | title = Mirror matter type dark matter | journal=International Journal of Modern Physics D | volume=13 | issue=10 | pages=2161–2192 | bibcode=2004IJMPD..13.2161F | s2cid=16148721 | arxiv=astro-ph/0407623 | doi=10.1142/S0218271804006449 }}
• {{cite journal |first=L.B. |last=Okun | year=2007 |title=Mirror particles and mirror matter: 50 years of speculation and search |journal=Physics-Uspekhi |volume=50 | issue=4 |pages=380–389 |bibcode=2007PhyU...50..380O | arxiv=hep-ph/0606202 | s2cid=12137927 | doi=10.1070/PU2007v050n04ABEH006227 }}
• {{cite journal |first=Z.K. |last=Silagadze | year=2001 |title=TeV scale gravity, mirror universe, and ... dinosaurs | journal=Acta Physica Polonica B | volume=32 | issue=1 | pages=99–128 | bibcode=2001AcPPB..32...99S | arxiv=hep-ph/0002255 }}

{{refend}}

{{Dark matter}}

{{DEFAULTSORT:Mirror Matter}}

Category:Physics beyond the Standard Model

Category:Astroparticle physics

Category:Dark matter

Category:Hypothetical particles