Large extra dimensions

In particle physics and string theory (M-theory), the ADD model, also known as the model with large extra dimensions (LED), is a model framework that attempts to solve the hierarchy problem (Why is the force of gravity so weak compared to the electromagnetic force and the other fundamental forces?). The model tries to explain this problem by postulating that our universe, with its four dimensions (three spatial ones plus time), exists on a membrane in a higher dimensional space. It is then suggested that the other forces of nature (the electromagnetic force, strong interaction, and weak interaction) operate within this membrane and its four dimensions, while the hypothetical gravity-bearing particle, the graviton, can propagate across the extra dimensions. This would explain why gravity is very weak compared to the other fundamental forces.[clarification needed][1] The size of the dimensions in ADD is around the order of the TeV scale, which results in it being experimentally probeable by current colliders, unlike many exotic extra dimensional hypotheses that have the relevant size around the Planck scale.[2]

The model was proposed by Nima Arkani-Hamed, Savas Dimopoulos, and Gia Dvali in 1998.[3][4]

One way to test the theory is performed by colliding together two protons in the Large Hadron Collider so that they interact and produce particles. If a graviton were to be formed in the collision, it could propagate into the extra dimensions, resulting in an imbalance of transverse momentum. No experiments from the Large Hadron Collider have been decisive thus far.[5][6][7][8][9][10] However, the operation range of the LHC (13 TeV collision energy) covers only a small part of the predicted range in which evidence for LED would be recorded (a few TeV to 1016 TeV).[11] This suggests that the theory might be more thoroughly tested with more advanced technology.

  1. ^ For a pedagogical introduction, see Shifman, M. (2010). "Large Extra Dimensions: Becoming Acquainted with an Alternative Paradigm". International Journal of Modern Physics A. 25 (2n03): 199–225. arXiv:0907.3074. Bibcode:2010IJMPA..25..199S. CiteSeerX 10.1.1.314.3579. doi:10.1142/S0217751X10048548. S2CID 15019013.
  2. ^ Hossenfelder, Sabine (2012-12-21). "Backreaction: Large Extra Dimensions – Not Dead Yet". Backreaction. Retrieved 2019-04-03.
  3. ^ N. Arkani-Hamed; S. Dimopoulos; G. Dvali (1998). "The Hierarchy problem and new dimensions at a millimeter". Physics Letters. B429 (3–4): 263–272. arXiv:hep-ph/9803315. Bibcode:1998PhLB..429..263A. doi:10.1016/S0370-2693(98)00466-3. S2CID 15903444.
  4. ^ N. Arkani-Hamed; S. Dimopoulos; G. Dvali (1999). "Phenomenology, astrophysics and cosmology of theories with submillimeter dimensions and TeV scale quantum gravity". Physical Review. D59 (8): 086004. arXiv:hep-ph/9807344. Bibcode:1999PhRvD..59h6004A. CiteSeerX 10.1.1.345.9889. doi:10.1103/PhysRevD.59.086004. S2CID 18385871.
  5. ^ CMS Collaboration (2011). "Search for Microscopic Black Hole Signatures at the Large Hadron Collider". Physics Letters B. 697 (5): 434–453. arXiv:1012.3375. Bibcode:2011PhLB..697..434C. doi:10.1016/j.physletb.2011.02.032. S2CID 118488193.
  6. ^ CMS Collaboration (2012). "Search for microscopic black holes in pp collisions at s = 7 TeV". Journal of High Energy Physics. 2012 (4): 61. arXiv:1202.6396. Bibcode:2012JHEP...04..061C. doi:10.1007/JHEP04(2012)061. S2CID 119117436.
  7. ^ ATLAS Collaboration (2013). "Search for microscopic black holes in a like-sign dimuon final state using large track multiplicity with the ATLAS detector". Physical Review D. 88 (7): 072001. arXiv:1308.4075. Bibcode:2013PhRvD..88g2001A. doi:10.1103/PhysRevD.88.072001. S2CID 119088864.
  8. ^ ATLAS Collaboration (2014). "Search for Quantum Black-Hole Production in High-Invariant-Mass Lepton+Jet Final States Using Proton–Proton Collisions at s = 8 TeV and the ATLAS Detector". Physical Review Letters. 112 (9): 091804. arXiv:1311.2006. Bibcode:2014PhRvL.112i1804A. doi:10.1103/PhysRevLett.112.091804. PMID 24655244. S2CID 204934578.
  9. ^ ATLAS Collaboration (2014). "Search for microscopic black holes and string balls in final states with leptons and jets with the ATLAS detector at s = 8 TeV". Journal of High Energy Physics. 2014 (8): 103. arXiv:1405.4254. Bibcode:2014JHEP...08..103A. doi:10.1007/JHEP08(2014)103. S2CID 119279313.
  10. ^ ATLAS Collaboration (2016). "Search for strong gravity in multijet final states produced in pp collisions at s = 13 TeV using the ATLAS detector at the LHC". Journal of High Energy Physics. 2016 (3): 26. arXiv:1512.02586. Bibcode:2016JHEP...03..026A. doi:10.1007/JHEP03(2016)026. S2CID 119200293.
  11. ^ "Reality check at the LHC". Physics World. 18 January 2011. Retrieved 2016-05-11.