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Supergravity

In theoretical physics, supergravity (supergravity theory; SUGRA for short) is a modern field theory that combines the principles of supersymmetry and general relativity; this is in contrast to non-gravitational supersymmetric theories such as the Minimal Supersymmetric Standard Model. Supergravity is the gauge theory of local supersymmetry. Since the supersymmetry (SUSY) generators form together with the Poincaré algebra a superalgebra, called the super-Poincaré algebra, supersymmetry as a gauge theory makes gravity arise in a natural way.[1]

Gravitons edit

Like all covariant approaches to quantum gravity,[2] supergravity contains a spin-2 field whose quantum is the graviton. Supersymmetry requires the graviton field to have a superpartner. This field has spin 3/2 and its quantum is the gravitino. The number of gravitino fields is equal to the number of supersymmetries.

History edit

Gauge supersymmetry edit

The first theory of local supersymmetry was proposed by Dick Arnowitt and Pran Nath in 1975[3] and was called gauge supersymmetry.

Supergravity edit

The first model of 4-dimensional supergravity (without this denotation) was formulated by Dmitri Vasilievich Volkov and Vyacheslav A. Soroka in 1973,[4] emphasizing the importance of spontaneous supersymmetry breaking for the possibility of a realistic model. The minimal version of 4-dimensional supergravity (with unbroken local supersymmetry) was constructed in detail in 1976 by Dan Freedman, Sergio Ferrara and Peter van Nieuwenhuizen.[5] In 2019 the three were awarded a special Breakthrough Prize in Fundamental Physics for the discovery.[6] The key issue of whether or not the spin 3/2 field is consistently coupled was resolved in the nearly simultaneous paper, by Deser and Zumino,[7] which independently proposed the minimal 4-dimensional model. It was quickly generalized to many different theories in various numbers of dimensions and involving additional (N) supersymmetries. Supergravity theories with N>1 are usually referred to as extended supergravity (SUEGRA). Some supergravity theories were shown to be related to certain higher-dimensional supergravity theories via dimensional reduction (e.g. N=1, 11-dimensional supergravity is dimensionally reduced on T7 to 4-dimensional, ungauged, N = 8 supergravity). The resulting theories were sometimes referred to as Kaluza–Klein theories as Kaluza and Klein constructed in 1919 a 5-dimensional gravitational theory, that when dimensionally reduced on a circle, its 4-dimensional non-massive modes describe electromagnetism coupled to gravity.

mSUGRA edit

mSUGRA means minimal SUper GRAvity. The construction of a realistic model of particle interactions within the N = 1 supergravity framework where supersymmetry (SUSY) breaks by a super Higgs mechanism carried out by Ali Chamseddine, Richard Arnowitt and Pran Nath in 1982. Collectively now known as minimal supergravity Grand Unification Theories (mSUGRA GUT), gravity mediates the breaking of SUSY through the existence of a hidden sector. mSUGRA naturally generates the Soft SUSY breaking terms which are a consequence of the Super Higgs effect. Radiative breaking of electroweak symmetry through Renormalization Group Equations (RGEs) follows as an immediate consequence. Due to its predictive power, requiring only four input parameters and a sign to determine the low energy phenomenology from the scale of Grand Unification, its interest is a widely investigated model of particle physics

11D: the maximal SUGRA edit

One of these supergravities, the 11-dimensional theory, generated considerable excitement as the first potential candidate for the theory of everything. This excitement was built on four pillars, two of which have now been largely discredited:

  • In 1980 Peter Freund and M. A. Rubin showed that compactification from 11 dimensions preserving all the SUSY generators could occur in two ways, leaving only 4 or 7 macroscopic dimensions, the others compact.[11] The noncompact dimensions have to form an anti-de Sitter space. There are many possible compactifications, but the Freund-Rubin compactification's invariance under all of the supersymmetry transformations preserves the action.

Finally, the first two results each appeared to establish 11 dimensions, the third result appeared to specify the theory, and the last result explained why the observed universe appears to be four-dimensional.

Many of the details of the theory were fleshed out by Peter van Nieuwenhuizen, Sergio Ferrara and Daniel Z. Freedman.

The end of the SUGRA era edit

The initial excitement over 11-dimensional supergravity soon waned, as various failings were discovered, and attempts to repair the model failed as well. Problems included:[citation needed]

  • The compact manifolds which were known at the time and which contained the standard model were not compatible with supersymmetry, and could not hold quarks or leptons. One suggestion was to replace the compact dimensions with the 7-sphere, with the symmetry group SO(8), or the squashed 7-sphere, with symmetry group SO(5) times SU(2).
  • Until recently, the physical neutrinos seen in experiments were believed to be massless, and appeared to be left-handed, a phenomenon referred to as the chirality of the Standard Model. It was very difficult to construct a chiral fermion from a compactification — the compactified manifold needed to have singularities, but physics near singularities did not begin to be understood until the advent of orbifold conformal field theories in the late 1980s.
  • Supergravity models generically result in an unrealistically large cosmological constant in four dimensions, and that constant is difficult to remove, and so require fine-tuning. This is still a problem today.
  • Quantization of the theory led to quantum field theory gauge anomalies rendering the theory inconsistent. In the intervening years physicists have learned how to cancel these anomalies.

Some of these difficulties could be avoided by moving to a 10-dimensional theory involving superstrings. However, by moving to 10 dimensions one loses the sense of uniqueness of the 11-dimensional theory.[12]

The core breakthrough for the 10-dimensional theory, known as the first superstring revolution, was a demonstration by Michael B. Green, John H. Schwarz and David Gross that there are only three supergravity models in 10 dimensions which have gauge symmetries and in which all of the gauge and gravitational anomalies cancel. These were theories built on the groups SO(32) and  , the direct product of two copies of E8. Today we know that, using D-branes for example, gauge symmetries can be introduced in other 10-dimensional theories as well.[13]

The second superstring revolution edit

Initial excitement about the 10-dimensional theories, and the string theories that provide their quantum completion, died by the end of the 1980s. There were too many Calabi–Yaus to compactify on, many more than Yau had estimated, as he admitted in December 2005 at the 23rd International Solvay Conference in Physics. None quite gave the standard model, but it seemed as though one could get close with enough effort in many distinct ways. Plus no one understood the theory beyond the regime of applicability of string perturbation theory.

There was a comparatively quiet period at the beginning of the 1990s; however, several important tools were developed. For example, it became apparent that the various superstring theories were related by "string dualities", some of which relate weak string-coupling - perturbative - physics in one model with strong string-coupling - non-perturbative - in another.

Then the second superstring revolution occurred. Joseph Polchinski realized that obscure string theory objects, called D-branes, which he discovered six years earlier, equate to stringy versions of the p-branes known in supergravity theories. String theory perturbation didn't restrict these p-branes. Thanks to supersymmetry, p-branes in supergravity gained understanding well beyond the limits of string theory.

Armed with this new nonperturbative tool, Edward Witten and many others could show all of the perturbative string theories as descriptions of different states in a single theory that Witten named M-theory. Furthermore, he argued that M-theory's long wavelength limit, i.e. when the quantum wavelength associated to objects in the theory appear much larger than the size of the 11th dimension, needs 11-dimensional supergravity descriptors that fell out of favor with the first superstring revolution 10 years earlier, accompanied by the 2- and 5-branes.

Therefore, supergravity comes full circle and uses a common framework in understanding features of string theories, M-theory, and their compactifications to lower spacetime dimensions.

Relation to superstrings edit

The term "low energy limits" labels some 10-dimensional supergravity theories. These arise as the massless, tree-level approximation of string theories. True effective field theories of string theories, rather than truncations, are rarely available. Due to string dualities, the conjectured 11-dimensional M-theory is required to have 11-dimensional supergravity as a "low energy limit". However, this doesn't necessarily mean that string theory/M-theory is the only possible UV completion of supergravity;[citation needed] supergravity research is useful independent of those relations.

4D N = 1 SUGRA edit

Before we move on to SUGRA proper, let's recapitulate some important details about general relativity. We have a 4D differentiable manifold M with a Spin(3,1) principal bundle over it. This principal bundle represents the local Lorentz symmetry. In addition, we have a vector bundle T over the manifold with the fiber having four real dimensions and transforming as a vector under Spin(3,1). We have an invertible linear map from the tangent bundle TM[which?] to T. This map is the vierbein. The local Lorentz symmetry has a gauge connection associated with it, the spin connection.

The following discussion will be in superspace notation, as opposed to the component notation, which isn't manifestly covariant under SUSY. There are actually many different versions of SUGRA out there which are inequivalent in the sense that their actions and constraints upon the torsion tensor are different, but ultimately equivalent in that we can always perform a field redefinition of the supervierbeins and spin connection to get from one version to another.

In 4D N=1 SUGRA, we have a 4|4 real differentiable supermanifold M, i.e. we have 4 real bosonic dimensions and 4 real fermionic dimensions. As in the nonsupersymmetric case, we have a Spin(3,1) principal bundle over M. We have an R4|4 vector bundle T over M. The fiber of T transforms under the local Lorentz group as follows; the four real bosonic dimensions transform as a vector and the four real fermionic dimensions transform as a Majorana spinor. This Majorana spinor can be reexpressed as a complex left-handed Weyl spinor and its complex conjugate right-handed Weyl spinor (they're not independent of each other). We also have a spin connection as before.

We will use the following conventions; the spatial (both bosonic and fermionic) indices will be indicated by M, N, ... . The bosonic spatial indices will be indicated by μ, ν, ..., the left-handed Weyl spatial indices by α, β,..., and the right-handed Weyl spatial indices by  ,  , ... . The indices for the fiber of T will follow a similar notation, except that they will be hatted like this:  . See van der Waerden notation for more details.  . The supervierbein is denoted by  , and the spin connection by  . The inverse supervierbein is denoted by  .

The supervierbein and spin connection are real in the sense that they satisfy the reality conditions

  where  ,  , and   and  .

The covariant derivative is defined as

 .

The covariant exterior derivative as defined over supermanifolds needs to be super graded. This means that every time we interchange two fermionic indices, we pick up a +1 sign factor, instead of -1.

The presence or absence of R symmetries is optional, but if R-symmetry exists, the integrand over the full superspace has to have an R-charge of 0 and the integrand over chiral superspace has to have an R-charge of 2.

A chiral superfield X is a superfield which satisfies  . In order for this constraint to be consistent, we require the integrability conditions that   for some coefficients c.

Unlike nonSUSY GR, the torsion has to be nonzero, at least with respect to the fermionic directions. Already, even in flat superspace,  . In one version of SUGRA (but certainly not the only one), we have the following constraints upon the torsion tensor:

 
 
 
 
 
 

Here,   is a shorthand notation to mean the index runs over either the left or right Weyl spinors.

The superdeterminant of the supervierbein,  , gives us the volume factor for M. Equivalently, we have the volume 4|4-superform .

If we complexify the superdiffeomorphisms, there is a gauge where  ,   and  . The resulting chiral superspace has the coordinates x and Θ.

R is a scalar valued chiral superfield derivable from the supervielbeins and spin connection. If f is any superfield,   is always a chiral superfield.

The action for a SUGRA theory with chiral superfields X, is given by

 

where K is the Kähler potential and W is the superpotential, and   is the chiral volume factor.

Unlike the case for flat superspace, adding a constant to either the Kähler or superpotential is now physical. A constant shift to the Kähler potential changes the effective Planck constant, while a constant shift to the superpotential changes the effective cosmological constant. As the effective Planck constant now depends upon the value of the chiral superfield X, we need to rescale the supervierbeins (a field redefinition) to get a constant Planck constant. This is called the Einstein frame.

N = 8 supergravity in 4 dimensions edit

N = 8 supergravity is the most symmetric quantum field theory which involves gravity and a finite number of fields. It can be found from a dimensional reduction of 11D supergravity by making the size of 7 of the dimensions go to zero. It has 8 supersymmetries which is the most any gravitational theory can have since there are 8 half-steps between spin 2 and spin −2. (A graviton has the highest spin in this theory which is a spin 2 particle.) More supersymmetries would mean the particles would have superpartners with spins higher than 2. The only theories with spins higher than 2 which are consistent involve an infinite number of particles (such as string theory and higher-spin theories). Stephen Hawking in his A Brief History of Time speculated that this theory could be the Theory of Everything. However, in later years this was abandoned in favour of string theory. There has been renewed interest in the 21st century with the possibility that this theory may be finite.

Higher-dimensional SUGRA edit

Higher-dimensional SUGRA is the higher-dimensional, supersymmetric generalization of general relativity. Supergravity can be formulated in any number of dimensions up to eleven. Higher-dimensional SUGRA focuses upon supergravity in greater than four dimensions.

The number of supercharges in a spinor depends on the dimension and the signature of spacetime. The supercharges occur in spinors. Thus the limit on the number of supercharges cannot be satisfied in a spacetime of arbitrary dimension. Some theoretical examples in which this is satisfied are:

  • 12-dimensional two-time theory
  • 11-dimensional maximal SUGRA
  • 10-dimensional SUGRA theories
    • Type IIA SUGRA: N = (1, 1)
    • IIA SUGRA from 11d SUGRA
    • Type IIB SUGRA: N = (2, 0)
    • Type I gauged SUGRA: N = (1, 0)
  • 9d SUGRA theories
    • Maximal 9d SUGRA from 10d
    • T-duality
    • N = 1 Gauged SUGRA

The supergravity theories that have attracted the most interest contain no spins higher than two. This means, in particular, that they do not contain any fields that transform as symmetric tensors of rank higher than two under Lorentz transformations. The consistency of interacting higher spin field theories is, however, presently a field of very active interest.

See also edit

Notes edit

  1. ^ Van Nieuwenhuizen, P. (1981). "Supergravity". Physics Reports. 68 (4): 189–398. Bibcode:1981PhR....68..189V. doi:10.1016/0370-1573(81)90157-5.
  2. ^ Rovelli, Carlo (2000). "Notes for a brief history of quantum gravity". arXiv:gr-qc/0006061.
  3. ^ Nath, P.; Arnowitt, R. (1975). "Generalized Super-Gauge Symmetry as a New Framework for Unified Gauge Theories". Physics Letters B. 56 (2): 177. Bibcode:1975PhLB...56..177N. doi:10.1016/0370-2693(75)90297-x.
  4. ^ Volkov, D.V.; Soroka, V.A. (1973). "Higgs effect for Goldstone particles with spin 1/2". JETP Letters. 16 (11): 438–440. Bibcode:1973JETPL..18..312V. doi:10.1007/BFb0105271.
  5. ^ Freedman, D.Z.; van Nieuwenhuizen, P.; Ferrara, S. (1976). "Progress Toward A Theory Of Supergravity". Physical Review D. 13 (12): 3214–3218. Bibcode:1976PhRvD..13.3214F. doi:10.1103/physrevd.13.3214.
  6. ^ "Supergravity scientists share $3M US Breakthrough Prize". CBC News.
  7. ^ Deser, S.; Zumino, B. (1976). "Consistent Supergravity". Physics Letters B. 62 (3): 335–337. Bibcode:1976PhLB...62..335D. doi:10.1016/0370-2693(76)90089-7.
  8. ^ Nahm, Werner (1978). "Supersymmetries and their representations". Nuclear Physics B. 135 (1): 149–166. Bibcode:1978NuPhB.135..149N. doi:10.1016/0550-3213(78)90218-3.
  9. ^ Witten, Ed (1981). "Search for a realistic Kaluza-Klein theory". Nuclear Physics B. 186 (3): 412–428. Bibcode:1981NuPhB.186..412W. doi:10.1016/0550-3213(81)90021-3.
  10. ^ E. Cremmer, B. Julia and J. Scherk, "Supergravity theory in eleven dimensions", Physics Letters B76 (1978) pp 409-412,
  11. ^ Peter G.O. Freund; Mark A. Rubin (1980). "Dynamics of dimensional reduction". Physics Letters B. 97 (2): 233–235. Bibcode:1980PhLB...97..233F. doi:10.1016/0370-2693(80)90590-0.
  12. ^ Duff, M. J. (1998). "A Layman's Guide to M-theory". arXiv:hep-th/9805177.
  13. ^ Blumenhagen, R.; Cvetic, M.; Langacker, P.; Shiu, G. (2005). "Toward Realistic Intersecting D-Brane Models". Annual Review of Nuclear and Particle Science. 55 (1): 71–139. arXiv:hep-th/0502005. Bibcode:2005ARNPS..55...71B. doi:10.1146/annurev.nucl.55.090704.151541. S2CID 15148429.

References edit

Historical edit

  • Volkov, D.V.; Soroka, V.A (1973). "Higgs effect for goldstone particles with spin 1/2". Supersymmetry and Quantum Field Theory. Lecture Notes in Physics. Vol. 18. pp. 529–533. Bibcode:1973JETPL..18..312V. doi:10.1007/BFb0105271. ISBN 978-3-540-64623-5. {{cite book}}: |journal= ignored (help)
  • Nath, P.; Arnowitt, R. (1975). "Generalized super-gauge symmetry as a new framework for unified gauge theories". Physics Letters B. 56 (2): 177. Bibcode:1975PhLB...56..177N. doi:10.1016/0370-2693(75)90297-x.
  • Freedman, D.Z.; van Nieuwenhuizen, P.; Ferrara, S. (1976). "Progress toward a theory of supergravity". Physical Review D. 13 (12): 3214–3218. Bibcode:1976PhRvD..13.3214F. doi:10.1103/physrevd.13.3214.
  • Cremmer, E.; Julia, B.; Scherk, J. (1978). "Supergravity in theory in 11 dimensions". Physics Letters B. 76 (4): 409–412. Bibcode:1978PhLB...76..409C. doi:10.1016/0370-2693(78)90894-8.
  • Freund, P.; Rubin, M. (1980). "Dynamics of dimensional reduction". Physics Letters B. 97 (2): 233–235. Bibcode:1980PhLB...97..233F. doi:10.1016/0370-2693(80)90590-0.
  • Chamseddine, A. H.; Arnowitt, R.; Nath, Pran (1982). "Locally supersymmetric grand unification". Physical Review Letters. 49 (14): 970–974. Bibcode:1982PhRvL..49..970C. doi:10.1103/PhysRevLett.49.970.
  • Green, Michael B.; Schwarz, John H. (1984). "Anomaly cancellation in supersymmetric D = 10 gauge theory and superstring theory". Physics Letters B. 149 (1–3): 117–122. Bibcode:1984PhLB..149..117G. doi:10.1016/0370-2693(84)91565-x.
  • Deser, S. (2018). "A brief history (and geography) of supergravity: The first 3 weeks... and after" (PDF). The European Physical Journal H. 43 (3): 281–291. arXiv:1704.05886. Bibcode:2018EPJH...43..281D. doi:10.1140/epjh/e2018-90005-3. S2CID 119428513.
  • Duplij, S. (2019). "Supergravity was discovered by D.V. Volkov and V.A. Soroka in 1973, wasn't it?". East European Journal of Physics (3): 81–82. arXiv:1910.03259. doi:10.26565/2312-4334-2019-3-10.

General edit

  • de Wit, Bernard (2002). "Supergravity". arXiv:hep-th/0212245.
  • Pran, Nath (2017). Supersymmetry, Supergravity, and Unification. Cambridge University Press. ISBN 978-0-521-19702-1.
  • Martin, Stephen P. (1998). "A Supersymmetry Primer". In Kane, Gordon L. (ed.). Perspectives on Supersymmetry. Advanced Series on Directions in High Energy Physics. Vol. 18. World Scientific. pp. 1–98. arXiv:hep-ph/9709356. doi:10.1142/9789812839657_0001. ISBN 978-981-02-3553-6. S2CID 118973381.
  • Drees, Manuel; Godbole, Rohini M.; Roy, Probir (2004). Theory and Phenomenology of Sparticles. World Scientific. ISBN 9-810-23739-1.
  • Bilal, Adel (2001). "Introduction to Supersymmetry". arXiv:hep-th/0101055.
  • Brandt, Friedemann (2002). "Lectures on Supergravity". Fortschritte der Physik. 50 (10–11): 1126–1172. arXiv:hep-th/0204035. Bibcode:2002ForPh..50.1126B. doi:10.1002/1521-3978(200210)50:10/11<1126::AID-PROP1126>3.0.CO;2-B. S2CID 15471713.
  • Sezgin, Ergin (2023). "Survey of supergravities". arXiv:2312.06754 [hep-th].

Further reading edit

  • Dall'Agata, G., Zagermann, M., Supergravity: From First Principles to Modern Applications, Springer, (2021). ISBN 978-3662639788
  • Freedman, D. Z., Van Proeyen, A., Supergravity, Cambridge University Press, Cambridge, (2012). ISBN 978-0521194013
  • Lauria, E., Van Proeyen, A., N = 2 Supergravity in D = 4, 5, 6 Dimensions, Springer, (2020). ISBN 978-3030337551
  • Nath, P., Supersymmetry, Supergravity, and Unification, Cambridge University Press, Cambridge, (2016) ISBN 978-0521197021
  • Tanii, Y., Introduction to Supergravity, Springer, (2014). ISBN 978-4431548270
  • Rausch de Traubenberg, M., Valenzuela, M., A Supergravity Primer, World Scientific Press, Singapore, (2019). ISBN 978-9811210518
  • Wess, P., Introduction To Supersymmetry And Supergravity, World Scientific Press, Singapore, (1990). ISBN 978-9810200985
  • Wess, P., Bagger, J., Supersymmetry and Supergravity, Princeton University Press, Princeton, (1992). ISBN 978-0691025308

External links edit

  •   Quotations related to Supergravity at Wikiquote

supergravity, this, article, multiple, issues, please, help, improve, discuss, these, issues, talk, page, learn, when, remove, these, template, messages, this, article, technical, most, readers, understand, please, help, improve, make, understandable, experts,. This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages This article may be too technical for most readers to understand Please help improve it to make it understandable to non experts without removing the technical details April 2018 Learn how and when to remove this template message This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations December 2009 Learn how and when to remove this template message Learn how and when to remove this template message In theoretical physics supergravity supergravity theory SUGRA for short is a modern field theory that combines the principles of supersymmetry and general relativity this is in contrast to non gravitational supersymmetric theories such as the Minimal Supersymmetric Standard Model Supergravity is the gauge theory of local supersymmetry Since the supersymmetry SUSY generators form together with the Poincare algebra a superalgebra called the super Poincare algebra supersymmetry as a gauge theory makes gravity arise in a natural way 1 Contents 1 Gravitons 2 History 2 1 Gauge supersymmetry 2 2 Supergravity 2 3 mSUGRA 2 4 11D the maximal SUGRA 2 5 The end of the SUGRA era 2 6 The second superstring revolution 3 Relation to superstrings 4 4D N 1 SUGRA 5 N 8 supergravity in 4 dimensions 6 Higher dimensional SUGRA 7 See also 8 Notes 9 References 9 1 Historical 9 2 General 10 Further reading 11 External linksGravitons editLike all covariant approaches to quantum gravity 2 supergravity contains a spin 2 field whose quantum is the graviton Supersymmetry requires the graviton field to have a superpartner This field has spin 3 2 and its quantum is the gravitino The number of gravitino fields is equal to the number of supersymmetries History editGauge supersymmetry edit The first theory of local supersymmetry was proposed by Dick Arnowitt and Pran Nath in 1975 3 and was called gauge supersymmetry Supergravity edit The first model of 4 dimensional supergravity without this denotation was formulated by Dmitri Vasilievich Volkov and Vyacheslav A Soroka in 1973 4 emphasizing the importance of spontaneous supersymmetry breaking for the possibility of a realistic model The minimal version of 4 dimensional supergravity with unbroken local supersymmetry was constructed in detail in 1976 by Dan Freedman Sergio Ferrara and Peter van Nieuwenhuizen 5 In 2019 the three were awarded a special Breakthrough Prize in Fundamental Physics for the discovery 6 The key issue of whether or not the spin 3 2 field is consistently coupled was resolved in the nearly simultaneous paper by Deser and Zumino 7 which independently proposed the minimal 4 dimensional model It was quickly generalized to many different theories in various numbers of dimensions and involving additional N supersymmetries Supergravity theories with N gt 1 are usually referred to as extended supergravity SUEGRA Some supergravity theories were shown to be related to certain higher dimensional supergravity theories via dimensional reduction e g N 1 11 dimensional supergravity is dimensionally reduced on T7 to 4 dimensional ungauged N 8 supergravity The resulting theories were sometimes referred to as Kaluza Klein theories as Kaluza and Klein constructed in 1919 a 5 dimensional gravitational theory that when dimensionally reduced on a circle its 4 dimensional non massive modes describe electromagnetism coupled to gravity mSUGRA edit mSUGRA means minimal SUper GRAvity The construction of a realistic model of particle interactions within the N 1 supergravity framework where supersymmetry SUSY breaks by a super Higgs mechanism carried out by Ali Chamseddine Richard Arnowitt and Pran Nath in 1982 Collectively now known as minimal supergravity Grand Unification Theories mSUGRA GUT gravity mediates the breaking of SUSY through the existence of a hidden sector mSUGRA naturally generates the Soft SUSY breaking terms which are a consequence of the Super Higgs effect Radiative breaking of electroweak symmetry through Renormalization Group Equations RGEs follows as an immediate consequence Due to its predictive power requiring only four input parameters and a sign to determine the low energy phenomenology from the scale of Grand Unification its interest is a widely investigated model of particle physics See also Gravity Mediated Supersymmetry Breaking in the MSSM 11D the maximal SUGRA edit One of these supergravities the 11 dimensional theory generated considerable excitement as the first potential candidate for the theory of everything This excitement was built on four pillars two of which have now been largely discredited Werner Nahm showed 8 11 dimensions as the largest number of dimensions consistent with a single graviton and more dimensions will show particles with spins greater than 2 However if two of these dimensions are time like these problems are avoided in 12 dimensions Itzhak Bars citation needed gives this emphasis In 1981 Ed Witten showed 9 11 as the smallest number of dimensions big enough to contain the gauge groups of the Standard Model namely SU 3 for the strong interactions and SU 2 times U 1 for the electroweak interactions citation needed Many techniques exist to embed the standard model gauge group in supergravity in any number of dimensions like the obligatory gauge symmetry in type I and heterotic string theories and obtained in type II string theory by compactification on certain Calabi Yau manifolds The D branes engineer gauge symmetries too In 1978 Eugene Cremmer Bernard Julia and Joel Scherk CJS found 10 the classical action for an 11 dimensional supergravity theory This remains today the only known classical 11 dimensional theory with local supersymmetry and no fields of spin higher than two citation needed Other 11 dimensional theories known and quantum mechanically inequivalent reduce to the CJS theory when one imposes the classical equations of motion However in the mid 1980s Bernard de Wit and Hermann Nicolai found an alternate theory in D 11 Supergravity with Local SU 8 Invariance permanent dead link While not manifestly Lorentz invariant it is in many ways superior because it dimensionally reduces to the 4 dimensional theory without recourse to the classical equations of motion In 1980 Peter Freund and M A Rubin showed that compactification from 11 dimensions preserving all the SUSY generators could occur in two ways leaving only 4 or 7 macroscopic dimensions the others compact 11 The noncompact dimensions have to form an anti de Sitter space There are many possible compactifications but the Freund Rubin compactification s invariance under all of the supersymmetry transformations preserves the action Finally the first two results each appeared to establish 11 dimensions the third result appeared to specify the theory and the last result explained why the observed universe appears to be four dimensional Many of the details of the theory were fleshed out by Peter van Nieuwenhuizen Sergio Ferrara and Daniel Z Freedman The end of the SUGRA era edit The initial excitement over 11 dimensional supergravity soon waned as various failings were discovered and attempts to repair the model failed as well Problems included citation needed The compact manifolds which were known at the time and which contained the standard model were not compatible with supersymmetry and could not hold quarks or leptons One suggestion was to replace the compact dimensions with the 7 sphere with the symmetry group SO 8 or the squashed 7 sphere with symmetry group SO 5 times SU 2 Until recently the physical neutrinos seen in experiments were believed to be massless and appeared to be left handed a phenomenon referred to as the chirality of the Standard Model It was very difficult to construct a chiral fermion from a compactification the compactified manifold needed to have singularities but physics near singularities did not begin to be understood until the advent of orbifold conformal field theories in the late 1980s Supergravity models generically result in an unrealistically large cosmological constant in four dimensions and that constant is difficult to remove and so require fine tuning This is still a problem today Quantization of the theory led to quantum field theory gauge anomalies rendering the theory inconsistent In the intervening years physicists have learned how to cancel these anomalies Some of these difficulties could be avoided by moving to a 10 dimensional theory involving superstrings However by moving to 10 dimensions one loses the sense of uniqueness of the 11 dimensional theory 12 The core breakthrough for the 10 dimensional theory known as the first superstring revolution was a demonstration by Michael B Green John H Schwarz and David Gross that there are only three supergravity models in 10 dimensions which have gauge symmetries and in which all of the gauge and gravitational anomalies cancel These were theories built on the groups SO 32 and E8 E8 displaystyle E 8 times E 8 nbsp the direct product of two copies of E8 Today we know that using D branes for example gauge symmetries can be introduced in other 10 dimensional theories as well 13 The second superstring revolution edit Initial excitement about the 10 dimensional theories and the string theories that provide their quantum completion died by the end of the 1980s There were too many Calabi Yaus to compactify on many more than Yau had estimated as he admitted in December 2005 at the 23rd International Solvay Conference in Physics None quite gave the standard model but it seemed as though one could get close with enough effort in many distinct ways Plus no one understood the theory beyond the regime of applicability of string perturbation theory There was a comparatively quiet period at the beginning of the 1990s however several important tools were developed For example it became apparent that the various superstring theories were related by string dualities some of which relate weak string coupling perturbative physics in one model with strong string coupling non perturbative in another Then the second superstring revolution occurred Joseph Polchinski realized that obscure string theory objects called D branes which he discovered six years earlier equate to stringy versions of the p branes known in supergravity theories String theory perturbation didn t restrict these p branes Thanks to supersymmetry p branes in supergravity gained understanding well beyond the limits of string theory Armed with this new nonperturbative tool Edward Witten and many others could show all of the perturbative string theories as descriptions of different states in a single theory that Witten named M theory Furthermore he argued that M theory s long wavelength limit i e when the quantum wavelength associated to objects in the theory appear much larger than the size of the 11th dimension needs 11 dimensional supergravity descriptors that fell out of favor with the first superstring revolution 10 years earlier accompanied by the 2 and 5 branes Therefore supergravity comes full circle and uses a common framework in understanding features of string theories M theory and their compactifications to lower spacetime dimensions Relation to superstrings editThe term low energy limits labels some 10 dimensional supergravity theories These arise as the massless tree level approximation of string theories True effective field theories of string theories rather than truncations are rarely available Due to string dualities the conjectured 11 dimensional M theory is required to have 11 dimensional supergravity as a low energy limit However this doesn t necessarily mean that string theory M theory is the only possible UV completion of supergravity citation needed supergravity research is useful independent of those relations 4D N 1 SUGRA editBefore we move on to SUGRA proper let s recapitulate some important details about general relativity We have a 4D differentiable manifold M with a Spin 3 1 principal bundle over it This principal bundle represents the local Lorentz symmetry In addition we have a vector bundle T over the manifold with the fiber having four real dimensions and transforming as a vector under Spin 3 1 We have an invertible linear map from the tangent bundle TM which to T This map is the vierbein The local Lorentz symmetry has a gauge connection associated with it the spin connection The following discussion will be in superspace notation as opposed to the component notation which isn t manifestly covariant under SUSY There are actually many different versions of SUGRA out there which are inequivalent in the sense that their actions and constraints upon the torsion tensor are different but ultimately equivalent in that we can always perform a field redefinition of the supervierbeins and spin connection to get from one version to another In 4D N 1 SUGRA we have a 4 4 real differentiable supermanifold M i e we have 4 real bosonic dimensions and 4 real fermionic dimensions As in the nonsupersymmetric case we have a Spin 3 1 principal bundle over M We have an R4 4 vector bundle T over M The fiber of T transforms under the local Lorentz group as follows the four real bosonic dimensions transform as a vector and the four real fermionic dimensions transform as a Majorana spinor This Majorana spinor can be reexpressed as a complex left handed Weyl spinor and its complex conjugate right handed Weyl spinor they re not independent of each other We also have a spin connection as before We will use the following conventions the spatial both bosonic and fermionic indices will be indicated by M N The bosonic spatial indices will be indicated by m n the left handed Weyl spatial indices by a b and the right handed Weyl spatial indices by a displaystyle dot alpha nbsp b displaystyle dot beta nbsp The indices for the fiber of T will follow a similar notation except that they will be hatted like this M a displaystyle hat M hat alpha nbsp See van der Waerden notation for more details M m a a displaystyle M mu alpha dot alpha nbsp The supervierbein is denoted by eNM displaystyle e N hat M nbsp and the spin connection by wM N P displaystyle omega hat M hat N P nbsp The inverse supervierbein is denoted by EM N displaystyle E hat M N nbsp The supervierbein and spin connection are real in the sense that they satisfy the reality conditions eNM x 8 8 eN M x 8 8 displaystyle e N hat M x overline theta theta e N hat M x theta overline theta nbsp where m m displaystyle mu mu nbsp a a displaystyle alpha dot alpha nbsp and a a displaystyle dot alpha alpha nbsp and w x 8 8 w x 8 8 displaystyle omega x overline theta theta omega x theta overline theta nbsp The covariant derivative is defined as DM f EM N Nf wN f displaystyle D hat M f E hat M N left partial N f omega N f right nbsp The covariant exterior derivative as defined over supermanifolds needs to be super graded This means that every time we interchange two fermionic indices we pick up a 1 sign factor instead of 1 The presence or absence of R symmetries is optional but if R symmetry exists the integrand over the full superspace has to have an R charge of 0 and the integrand over chiral superspace has to have an R charge of 2 A chiral superfield X is a superfield which satisfies D a X 0 displaystyle overline D hat dot alpha X 0 nbsp In order for this constraint to be consistent we require the integrability conditions that D a D b ca b g D g displaystyle left overline D hat dot alpha overline D hat dot beta right c hat dot alpha hat dot beta hat dot gamma overline D hat dot gamma nbsp for some coefficients c Unlike nonSUSY GR the torsion has to be nonzero at least with respect to the fermionic directions Already even in flat superspace Da ea D a ea 0 displaystyle D hat alpha e hat dot alpha overline D hat dot alpha e hat alpha neq 0 nbsp In one version of SUGRA but certainly not the only one we have the following constraints upon the torsion tensor Ta b g 0 displaystyle T hat underline alpha hat underline beta hat underline gamma 0 nbsp Ta b m 0 displaystyle T hat alpha hat beta hat mu 0 nbsp Ta b m 0 displaystyle T hat dot alpha hat dot beta hat mu 0 nbsp Ta b m 2isa b m displaystyle T hat alpha hat dot beta hat mu 2i sigma hat alpha hat dot beta hat mu nbsp Tm a n 0 displaystyle T hat mu hat underline alpha hat nu 0 nbsp Tm n r 0 displaystyle T hat mu hat nu hat rho 0 nbsp Here a displaystyle underline alpha nbsp is a shorthand notation to mean the index runs over either the left or right Weyl spinors The superdeterminant of the supervierbein e displaystyle left e right nbsp gives us the volume factor for M Equivalently we have the volume 4 4 superformem 0 em 3 ea 1 ea 2 ea 1 ea 2 displaystyle e hat mu 0 wedge cdots wedge e hat mu 3 wedge e hat alpha 1 wedge e hat alpha 2 wedge e hat dot alpha 1 wedge e hat dot alpha 2 nbsp If we complexify the superdiffeomorphisms there is a gauge where Ea m 0 displaystyle E hat dot alpha mu 0 nbsp Ea b 0 displaystyle E hat dot alpha beta 0 nbsp and Ea b da b displaystyle E hat dot alpha dot beta delta dot alpha dot beta nbsp The resulting chiral superspace has the coordinates x and 8 R is a scalar valued chiral superfield derivable from the supervielbeins and spin connection If f is any superfield D 2 8R f displaystyle left bar D 2 8R right f nbsp is always a chiral superfield The action for a SUGRA theory with chiral superfields X is given by S d4xd282E 38 D 2 8R e K X X 3 W X c c displaystyle S int d 4 xd 2 Theta 2 mathcal E left frac 3 8 left bar D 2 8R right e K bar X X 3 W X right c c nbsp where K is the Kahler potential and W is the superpotential and E displaystyle mathcal E nbsp is the chiral volume factor Unlike the case for flat superspace adding a constant to either the Kahler or superpotential is now physical A constant shift to the Kahler potential changes the effective Planck constant while a constant shift to the superpotential changes the effective cosmological constant As the effective Planck constant now depends upon the value of the chiral superfield X we need to rescale the supervierbeins a field redefinition to get a constant Planck constant This is called the Einstein frame N 8 supergravity in 4 dimensions editN 8 supergravity is the most symmetric quantum field theory which involves gravity and a finite number of fields It can be found from a dimensional reduction of 11D supergravity by making the size of 7 of the dimensions go to zero It has 8 supersymmetries which is the most any gravitational theory can have since there are 8 half steps between spin 2 and spin 2 A graviton has the highest spin in this theory which is a spin 2 particle More supersymmetries would mean the particles would have superpartners with spins higher than 2 The only theories with spins higher than 2 which are consistent involve an infinite number of particles such as string theory and higher spin theories Stephen Hawking in his A Brief History of Time speculated that this theory could be the Theory of Everything However in later years this was abandoned in favour of string theory There has been renewed interest in the 21st century with the possibility that this theory may be finite Higher dimensional SUGRA editMain article Higher dimensional supergravity Higher dimensional SUGRA is the higher dimensional supersymmetric generalization of general relativity Supergravity can be formulated in any number of dimensions up to eleven Higher dimensional SUGRA focuses upon supergravity in greater than four dimensions The number of supercharges in a spinor depends on the dimension and the signature of spacetime The supercharges occur in spinors Thus the limit on the number of supercharges cannot be satisfied in a spacetime of arbitrary dimension Some theoretical examples in which this is satisfied are 12 dimensional two time theory 11 dimensional maximal SUGRA 10 dimensional SUGRA theories Type IIA SUGRA N 1 1 IIA SUGRA from 11d SUGRA Type IIB SUGRA N 2 0 Type I gauged SUGRA N 1 0 9d SUGRA theories Maximal 9d SUGRA from 10d T duality N 1 Gauged SUGRAThe supergravity theories that have attracted the most interest contain no spins higher than two This means in particular that they do not contain any fields that transform as symmetric tensors of rank higher than two under Lorentz transformations The consistency of interacting higher spin field theories is however presently a field of very active interest See also editGeneral relativity Grand Unified Theory M theory N 8 supergravity Quantum mechanics String theory Supermanifold Super Poincare algebra Supersymmetry SupermetricNotes edit Van Nieuwenhuizen P 1981 Supergravity Physics Reports 68 4 189 398 Bibcode 1981PhR 68 189V doi 10 1016 0370 1573 81 90157 5 Rovelli Carlo 2000 Notes for a brief history of quantum gravity arXiv gr qc 0006061 Nath P Arnowitt R 1975 Generalized Super Gauge Symmetry as a New Framework for Unified Gauge Theories Physics Letters B 56 2 177 Bibcode 1975PhLB 56 177N doi 10 1016 0370 2693 75 90297 x Volkov D V Soroka V A 1973 Higgs effect for Goldstone particles with spin 1 2 JETP Letters 16 11 438 440 Bibcode 1973JETPL 18 312V doi 10 1007 BFb0105271 Freedman D Z van Nieuwenhuizen P Ferrara S 1976 Progress Toward A Theory Of Supergravity Physical Review D 13 12 3214 3218 Bibcode 1976PhRvD 13 3214F doi 10 1103 physrevd 13 3214 Supergravity scientists share 3M US Breakthrough Prize CBC News Deser S Zumino B 1976 Consistent Supergravity Physics Letters B 62 3 335 337 Bibcode 1976PhLB 62 335D doi 10 1016 0370 2693 76 90089 7 Nahm Werner 1978 Supersymmetries and their representations Nuclear Physics B 135 1 149 166 Bibcode 1978NuPhB 135 149N doi 10 1016 0550 3213 78 90218 3 Witten Ed 1981 Search for a realistic Kaluza Klein theory Nuclear Physics B 186 3 412 428 Bibcode 1981NuPhB 186 412W doi 10 1016 0550 3213 81 90021 3 E Cremmer B Julia and J Scherk Supergravity theory in eleven dimensions Physics Letters B76 1978 pp 409 412 Peter G O Freund Mark A Rubin 1980 Dynamics of dimensional reduction Physics Letters B 97 2 233 235 Bibcode 1980PhLB 97 233F doi 10 1016 0370 2693 80 90590 0 Duff M J 1998 A Layman s Guide to M theory arXiv hep th 9805177 Blumenhagen R Cvetic M Langacker P Shiu G 2005 Toward Realistic Intersecting D Brane Models Annual Review of Nuclear and Particle Science 55 1 71 139 arXiv hep th 0502005 Bibcode 2005ARNPS 55 71B doi 10 1146 annurev nucl 55 090704 151541 S2CID 15148429 References editHistorical edit Volkov D V Soroka V A 1973 Higgs effect for goldstone particles with spin 1 2 Supersymmetry and Quantum Field Theory Lecture Notes in Physics Vol 18 pp 529 533 Bibcode 1973JETPL 18 312V doi 10 1007 BFb0105271 ISBN 978 3 540 64623 5 a href Template Cite book html title Template Cite book cite book a journal ignored help Nath P Arnowitt R 1975 Generalized super gauge symmetry as a new framework for unified gauge theories Physics Letters B 56 2 177 Bibcode 1975PhLB 56 177N doi 10 1016 0370 2693 75 90297 x Freedman D Z van Nieuwenhuizen P Ferrara S 1976 Progress toward a theory of supergravity Physical Review D 13 12 3214 3218 Bibcode 1976PhRvD 13 3214F doi 10 1103 physrevd 13 3214 Cremmer E Julia B Scherk J 1978 Supergravity in theory in 11 dimensions Physics Letters B 76 4 409 412 Bibcode 1978PhLB 76 409C doi 10 1016 0370 2693 78 90894 8 Freund P Rubin M 1980 Dynamics of dimensional reduction Physics Letters B 97 2 233 235 Bibcode 1980PhLB 97 233F doi 10 1016 0370 2693 80 90590 0 Chamseddine A H Arnowitt R Nath Pran 1982 Locally supersymmetric grand unification Physical Review Letters 49 14 970 974 Bibcode 1982PhRvL 49 970C doi 10 1103 PhysRevLett 49 970 Green Michael B Schwarz John H 1984 Anomaly cancellation in supersymmetric D 10 gauge theory and superstring theory Physics Letters B 149 1 3 117 122 Bibcode 1984PhLB 149 117G doi 10 1016 0370 2693 84 91565 x Deser S 2018 A brief history and geography of supergravity The first 3 weeks and after PDF The European Physical Journal H 43 3 281 291 arXiv 1704 05886 Bibcode 2018EPJH 43 281D doi 10 1140 epjh e2018 90005 3 S2CID 119428513 Duplij S 2019 Supergravity was discovered by D V Volkov and V A Soroka in 1973 wasn t it East European Journal of Physics 3 81 82 arXiv 1910 03259 doi 10 26565 2312 4334 2019 3 10 General edit de Wit Bernard 2002 Supergravity arXiv hep th 0212245 Pran Nath 2017 Supersymmetry Supergravity and Unification Cambridge University Press ISBN 978 0 521 19702 1 Martin Stephen P 1998 A Supersymmetry Primer In Kane Gordon L ed Perspectives on Supersymmetry Advanced Series on Directions in High Energy Physics Vol 18 World Scientific pp 1 98 arXiv hep ph 9709356 doi 10 1142 9789812839657 0001 ISBN 978 981 02 3553 6 S2CID 118973381 Drees Manuel Godbole Rohini M Roy Probir 2004 Theory and Phenomenology of Sparticles World Scientific ISBN 9 810 23739 1 Bilal Adel 2001 Introduction to Supersymmetry arXiv hep th 0101055 Brandt Friedemann 2002 Lectures on Supergravity Fortschritte der Physik 50 10 11 1126 1172 arXiv hep th 0204035 Bibcode 2002ForPh 50 1126B doi 10 1002 1521 3978 200210 50 10 11 lt 1126 AID PROP1126 gt 3 0 CO 2 B S2CID 15471713 Sezgin Ergin 2023 Survey of supergravities arXiv 2312 06754 hep th Further reading editDall Agata G Zagermann M Supergravity From First Principles to Modern Applications Springer 2021 ISBN 978 3662639788 Freedman D Z Van Proeyen A Supergravity Cambridge University Press Cambridge 2012 ISBN 978 0521194013 Lauria E Van Proeyen A N 2 Supergravity in D 4 5 6 Dimensions Springer 2020 ISBN 978 3030337551 Nath P Supersymmetry Supergravity and Unification Cambridge University Press Cambridge 2016 ISBN 978 0521197021 Tanii Y Introduction to Supergravity Springer 2014 ISBN 978 4431548270 Rausch de Traubenberg M Valenzuela M A Supergravity Primer World Scientific Press Singapore 2019 ISBN 978 9811210518 Wess P Introduction To Supersymmetry And Supergravity World Scientific Press Singapore 1990 ISBN 978 9810200985 Wess P Bagger J Supersymmetry and Supergravity Princeton University Press Princeton 1992 ISBN 978 0691025308External links edit nbsp Quotations related to Supergravity at Wikiquote Portals nbsp Physics nbsp Science Retrieved from https en wikipedia org w index php title Supergravity amp oldid 1193459214, wikipedia, wiki, book, books, library,

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