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In theoretical ], the non-commutative Standard Model (best known as '''Spectral Standard Model''' In theoretical ], the '''non-commutative Standard Model''' (best known as '''Spectral Standard Model'''
<ref name="10.1007/JHEP09(2012)104"> <ref name="10.1007/JHEP09(2012)104">
{{cite journal | title = Resilience of the Spectral Standard Model {{cite journal | title = Resilience of the Spectral Standard Model
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| author1-link = Ali Chamseddine | author1-link = Ali Chamseddine
| author2-link = Alain Connes | author2-link = Alain Connes
| journal = ] | journal = ]
| year = 2012 | year = 2012
| doi = 10.1007/JHEP09(2012)104 | volume = 2012 | issue = 9 | page = 104 | doi = 10.1007/JHEP09(2012)104
| arxiv = 1208.1030 | arxiv = 1208.1030
| bibcode = 2012JHEP...09..104C | s2cid = 119254948 }}
⚫ }}
</ref> </ref>
<ref name="10.1007/JHEP11(2013)132"> <ref name="10.1007/JHEP11(2013)132">
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| author1-link = Ali Chamseddine | author1-link = Ali Chamseddine
| author2-link = Alain Connes | author2-link = Alain Connes
| journal = ] | journal = ]
| year = 2013 | year = 2013
| doi = 10.1007/JHEP11(2013)132 | volume = 2013 | issue = 11 | page = 132 | doi = 10.1007/JHEP11(2013)132
| arxiv = 1304.8050 | arxiv = 1304.8050
| bibcode = 2013JHEP...11..132C | s2cid = 18044831 }}
⚫ }}
</ref> </ref>
), is a model based on ] that unifies a modified form of ] with the ] (extended with right-handed neutrinos). ), is a model based on ] that unifies a modified form of ] with the ] (extended with right-handed neutrinos).


The model postulates that space-time is the product of a 4-dimensional compact spin manifold <math>\mathcal{M}</math> by a finite space <math>\mathcal{F}</math>. The full Lagrangian (in Euclidean signature) of the ] minimally coupled to gravity is obtained as pure gravity over that product space. It is therefore close in spirit to ] but without the problem of massive tower of states. The model postulates that space-time is the product of a 4-dimensional compact spin manifold <math>\mathcal{M}</math> by a finite space <math>\mathcal{F}</math>. The full Lagrangian (in Euclidean signature) of the ] minimally coupled to gravity is obtained as pure gravity over that product space. It is therefore close in spirit to ] but without the problem of massive tower of states.


The parameters of the model live at unification scale and physical predictions are obtained by running the parameters down through ]. The parameters of the model live at unification scale and physical predictions are obtained by running the parameters down through ].


It is worth stressing that it is more than a simple reformation of the ]. For example, the scalar sector and the fermions representations are more constrained than in ]. It is worth stressing that it is more than a simple reformation of the ]. For example, the scalar sector and the fermions representations are more constrained than in ].


==Motivation== ==Motivation==
Following ideas from ] and ], the spectral approach seeks unification by expressing all forces as pure gravity on a space <math>\mathcal{X}</math>. Following ideas from ] and ], the spectral approach seeks unification by expressing all forces as pure gravity on a space <math>\mathcal{X}</math>.


The group of invariance of such a space should combine the group of invariance of ] <math>Diff(\mathcal{M})</math> with <math>\mathcal{G} = Map(\mathcal{M}, G)</math>, the group of maps from <math>\mathcal{M}</math> to the standard model gauge group <math>G=SU(3) \times SU(2) \times U(1)</math>. The group of invariance of such a space should combine the group of invariance of ] <math>\text{Diff}(\mathcal{M})</math> with <math>\mathcal{G} = \text{Map}(\mathcal{M}, G)</math>, the group of maps from <math>\mathcal{M}</math> to the standard model gauge group <math>G=SU(3) \times SU(2) \times U(1)</math>.


<math>Diff(\mathcal{M})</math> acts on <math>\mathcal{G}</math> by permutations and the full group of symmetries of <math>\mathcal{X}</math> is the semi-direct product: <math>\text{Diff}(\mathcal{M})</math> acts on <math>\mathcal{G}</math> by permutations and the full group of symmetries of <math>\mathcal{X}</math> is the semi-direct product:
<math>Diff(\mathcal{X}) = \mathcal{G} \rtimes Diff(\mathcal{M})</math> <math>\text{Diff}(\mathcal{X}) = \mathcal{G} \rtimes \text{Diff}(\mathcal{M})</math>


Note that the group of invariance of <math>\mathcal{X}</math> is not a simple group as it always contains the normal subgroup <math>\mathcal{G}</math>. It was proved by Mather Note that the group of invariance of <math>\mathcal{X}</math> is not a simple group as it always contains the normal subgroup <math>\mathcal{G}</math>. It was proved by Mather
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| issue = 2 | issue = 2
| year = 1974 | year = 1974
| pages = 271-273 | pages = 271–273
| doi = 10.1090/S0002-9904-1974-13456-7 | doi = 10.1090/S0002-9904-1974-13456-7
| doi-access = free
}}
⚫ }}
</ref> </ref>
and Thurston and Thurston
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| volume = 80 | volume = 80
| year = 1974 | year = 1974
| pages = 304-307 | issue = 2 | pages = 304–307
| doi = 10.1090/S0002-9904-1974-13475-0 | doi = 10.1090/S0002-9904-1974-13475-0
| url = http://projecteuclid.org/euclid.bams/1183535407 | doi-access = free
}}
⚫ }}
</ref> </ref>
that for ordinary (commutative) manifolds, the connected component of the identity in <math>Diff(\mathcal{M})</math> is always a simple group, therefore no ordinary manifold can have this semi-direct product structure. that for ordinary (commutative) manifolds, the connected component of the identity in <math>\text{Diff}(\mathcal{M})</math> is always a simple group, therefore no ordinary manifold can have this semi-direct product structure.


It is nevertheless possible to find such a space by enlarging the notion of space. It is nevertheless possible to find such a space by enlarging the notion of space.


In ], spaces are specified in algebraic terms. The algebraic object corresponding to a diffeomorphism is the automorphism of the algebra of coordinates. If the algebra is taken non-commutative it has trivial automorphisms (so-called inner automorphisms). These inner automorphisms form a normal subgroup of the group of automorphisms and provide the correct group structure. In noncommutative geometry, spaces are specified in algebraic terms. The algebraic object corresponding to a diffeomorphism is the automorphism of the algebra of coordinates. If the algebra is taken non-commutative it has trivial automorphisms (so-called inner automorphisms). These inner automorphisms form a normal subgroup of the group of automorphisms and provide the correct group structure.


Picking different algebras then give rise to different symmetries. The Spectral Standard Model takes as input the algebra <math>A = C^{\infty}(M) \otimes A_F </math> where <math>C^{\infty}(M)</math> is the algebra of differentiable functions encoding the 4-dimensional manifold and <math>A_F = \mathbb{C} \oplus \mathbb{H} \oplus M_3(\mathbb{C})</math> is a finite dimensional algebra encoding the symmetries of the standard model. Picking different algebras then give rise to different symmetries. The Spectral Standard Model takes as input the algebra <math>A = C^{\infty}(M) \otimes A_F </math> where <math>C^{\infty}(M)</math> is the algebra of differentiable functions encoding the 4-dimensional manifold and <math>A_F = \mathbb{C} \oplus \mathbb{H} \oplus M_3(\mathbb{C})</math> is a finite dimensional algebra encoding the symmetries of the standard model.


==History== ==History==
First ideas to use ] to particle physics appeared in 1988-89 First ideas to use noncommutative geometry to particle physics appeared in 1988-89, <ref name="connes_1998_essay">
{{cite book
<ref name="connes_1998_essay">
⚫ | last = Connes | first = Alain | author-link = Alain Connes
⚫ {{cite journal | title = Essay on physics and noncommutative geometry
| year= 1990
⚫ | last = Connes | first = Alain
⚫ | chapter = Essay on physics and noncommutative geometry
| author-link = Alain Connes
| journal = The interface of mathematics and particle physics | title = The Interface of Mathematics and Particle Physics (Oxford, 1988)
| year = 1988 | pages=9–48
| series=Inst. Math. Appl. Conf. Ser., New Ser. |volume=24
}}
| publisher=Oxford University Press
</ref>
| location=New York
<ref name="dv_1988_dcdnc"> }}</ref><ref name="dv_1988_dcdnc">
{{cite journal | title = Dérivations et calcul différentiel non commutatif {{cite journal | title = Dérivations et calcul différentiel non commutatif
| last = Dubois-Violette | first = Michel | last = Dubois-Violette | first = Michel
| journal = Comptes Rendus de l'Académie des Sciences, Série I | journal = Comptes Rendus de l'Académie des Sciences, Série I
| issue = 307 | issue = 307
| pages = 403-408 | pages = 403–408
| year = 1988 | year = 1988
}} }}
⚫ </ref><ref name="DVKM_1989_CBNG">
</ref>
⚫ <ref name="DVKM_1989_CBNG">
{{cite journal | title = Classical bosons in a non-commutative geometry {{cite journal | title = Classical bosons in a non-commutative geometry
| last1 = Dubois-Violette | first1 = Michel | last1 = Dubois-Violette | first1 = Michel
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| number = 11 | number = 11
| year = 1989 | year = 1989
| page = 1709 | doi = 10.1088/0264-9381/6/11/023 | bibcode = 1989CQGra...6.1709D | s2cid = 250880966 }}
}}
⚫ </ref><ref name="10.1016/0370-2693(89)90083-X">
</ref>
⚫ <ref name="10.1016/0370-2693(89)90083-X">
{{cite journal | title = Gauge bosons in a noncommutative geometry {{cite journal | title = Gauge bosons in a noncommutative geometry
| last1 = Dubois-Violette | first1 = Michel | last1 = Dubois-Violette | first1 = Michel
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| issue = 4 | issue = 4
| year = 1989 | year = 1989
| pages = 495-488 | pages = 495–488
| doi = 10.1016/0370-2693(89)90083-X | doi = 10.1016/0370-2693(89)90083-X
| bibcode = 1989PhLB..217..485D }}
}}
⚫ </ref><ref name="10.1063/1.528917">
</ref>
⚫ <ref name="10.1063/1.528917">
{{cite journal | title = Noncommutative differential geometry and new models of gauge theory {{cite journal | title = Noncommutative differential geometry and new models of gauge theory
| last1 = Dubois-Violette | first1 = Michel | last1 = Dubois-Violette | first1 = Michel
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| issue = 31 | issue = 31
| year = 1989 | year = 1989
| pages = 495-488 | pages = 495–488
| doi = 10.1063/1.528917 | doi = 10.1063/1.528917
}} }}
⚫ </ref> and were formalized a couple of years later by ] and ] in what is known as the Connes-Lott model
</ref>
⚫ .<ref name="10.1016/0920-5632(91)90120-4">
⚫ , and were formalized a couple of years later by ] and ] in what is known as the Connes-Lott model
⚫ <ref name="10.1016/0920-5632(91)90120-4">
{{cite journal | title = Particle models and noncommutative geometry {{cite journal | title = Particle models and noncommutative geometry
| last1 = Connes | first1 = Alain | last1 = Connes | first1 = Alain
| last2 = Lott | first2 = John | last2 = Lott | first2 = John
| author1-link = Alain Connes | author1-link = Alain Connes
| author2-link = John Lott | author2-link = John Lott (mathematician)
| journal = Nuclear Physics B - Proceedings Supplements | journal = Nuclear Physics B - Proceedings Supplements
| year = 1991 | year = 1991
| doi = 10.1016/0920-5632(91)90120-4 | volume = 18 | issue = 2 | pages = 29–47 | doi = 10.1016/0920-5632(91)90120-4
| bibcode = 1991NuPhS..18...29C | hdl = 2027.42/29524 | hdl-access = free}}
}}
⚫ </ref> The Connes-Lott model did not incorporate the gravitational field.
</ref>
⚫ . The Connes-Lott model did not incorporate the gravitational field.


In 1997, ] and ] published a new action principle, the Spectral Action In 1997, ] and Alain Connes published a new action principle, the Spectral Action, <ref name="10.1007/s002200050126">
<ref name="10.1007/s002200050126">
{{cite journal | title = The Spectral Action Principle {{cite journal | title = The Spectral Action Principle
| last1 = Chamseddine | first1 = Ali H. | last1 = Chamseddine | first1 = Ali H.
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| author1-link = Ali Chamseddine | author1-link = Ali Chamseddine
| author2-link = Alain Connes | author2-link = Alain Connes
| journal = Communications in Mathematical Physics volume 186 | journal = Communications in Mathematical Physics
| pages = 731–750 | pages = 731–750
| year = 1997 | year = 1997
| doi = 10.1007/s002200050126 | volume = 186 | issue = 3 | doi = 10.1007/s002200050126
| arxiv = hep-th/9606001 | arxiv = hep-th/9606001
| bibcode = 1997CMaPh.186..731C | s2cid = 12292414 }}
}}
</ref>, that made possible to incorporate the gravitational field into the model. Nevertheless, it was quickly noted that the model suffered from the notorious fermion-doubling problem (quadrupling of the fermions) </ref> that made possible to incorporate the gravitational field into the model. Nevertheless, it was quickly noted that the model suffered from the notorious fermion-doubling problem (quadrupling of the fermions)
<ref name="10.1103/PhysRevD.55.6357"> <ref name="10.1103/PhysRevD.55.6357">
{{cite journal | title = Fermion Hilbert Space and Fermion Doubling in the Noncommutative Geometry Approach to Gauge Theories {{cite journal | title = Fermion Hilbert Space and Fermion Doubling in the Noncommutative Geometry Approach to Gauge Theories
Line 166: Line 163:
| issue = 10 | issue = 10
| year = 1997 | year = 1997
| doi = 10.1103/PhysRevD.55.6357 | pages = 6357–6366 | doi = 10.1103/PhysRevD.55.6357
| arxiv = hep-th/9610035 | arxiv = hep-th/9610035
| bibcode = 1997PhRvD..55.6357L | s2cid = 14692679 }}
}}
</ref> </ref>
<ref name="10.1016/S0370-2693(97)01310-5"> <ref name="10.1016/S0370-2693(97)01310-5">
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| last2 = Iochum | first2 = Bruno | last2 = Iochum | first2 = Bruno
| last3 = Schücker | first3 = Thomas | last3 = Schücker | first3 = Thomas
| journal = Physical Review B, 416 | journal = Physical Review B
| pages = 123-128 | volume = 416
| pages = 123–128
| year = 1998 | year = 1998
| doi = 10.1016/S0370-2693(97)01310-5 | issue = 1–2 | doi = 10.1016/S0370-2693(97)01310-5
| arxiv = hep-th/9709145 | arxiv = hep-th/9709145
| bibcode = 1998PhLB..416..123G | s2cid = 15557600 }}
}}
</ref> and required neutrinos to be massless. One year later, experiments in ] and ] began to show that solar and atmospheric neutrinos change flavors and therefore are massive, ruling out the Spectral Standard Model. </ref> and required neutrinos to be massless. One year later, experiments in ] and ] began to show that solar and atmospheric neutrinos change flavors and therefore are massive, ruling out the Spectral Standard Model.


Only in 2006 a solution to the latter problem was proposed, independently by ] Only in 2006 a solution to the latter problem was proposed, independently by ]<ref name="10.1063/1.2408400">
<ref name="10.1063/1.2408400">
{{cite journal | title = A Lorentzian version of the non-commutative geometry of the standard model of particle physics {{cite journal | title = A Lorentzian version of the non-commutative geometry of the standard model of particle physics
| last = Barrett | first = John W. | last = Barrett | first = John W.
| author-link=John W. Barrett | author-link=John W. Barrett (physicist)
| journal = Journal of Mathematical Physics, 48 | journal = Journal of Mathematical Physics
| year = 2006 | volume= 48
| doi = 10.1063/1.2408400 | year = 2007
| issue = 1 | page = 012303 | doi = 10.1063/1.2408400
| arxiv = hep-th/0608221 | arxiv = hep-th/0608221
| bibcode = 2007JMP....48a2303B | s2cid = 11511575 }}
}}
</ref> and ] </ref> and Alain Connes,<ref name="10.1088/1126-6708/2006/11/081">
<ref name="10.1088/1126-6708/2006/11/081">
{{cite journal | title = Noncommutative Geometry and the standard model with neutrino mixing {{cite journal | title = Noncommutative Geometry and the standard model with neutrino mixing
| last = Connes | first = Alain | last = Connes | first = Alain
Line 201: Line 198:
| volume = 2006 | volume = 2006
| year = 2006 | year = 2006
| doi = 10.1088/1126-6708/2006/11/081 | issue = 11 | page = 081 | doi = 10.1088/1126-6708/2006/11/081
| arxiv = hep-th/0608226 | arxiv = hep-th/0608226
| bibcode = 2006JHEP...11..081C | s2cid = 14419757 }}
}}
⚫ </ref> almost at the same time. They show that massive neutrinos can be incorporated into the model by disentangling the KO-dimension (which is defined modulo 8) from the metric dimension (which is zero) for the finite space. By setting the KO-dimension to be 6, not only massive neutrinos were possible, but the see-saw mechanism was imposed by the formalism and the fermion doubling problem was also addressed.
</ref>
, almost at the same time.
⚫ They show that massive neutrinos can be incorporated into the model by disentangling the KO-dimension (which is defined modulo 8) from the metric dimension (which is zero) for the finite space. By setting the KO-dimension to be 6, not only massive neutrinos were possible, but the see-saw mechanism was imposed by the formalism and the fermion doubling problem was also addressed.


The new version of the model was studied in The new version of the model was studied in
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| volume = 11 | volume = 11
| number = 6 | number = 6
| year = 2006 | year = 2007
| doi = 10.4310/ATMP.2007.v11.n6.a3 | pages = 991–1089 | doi = 10.4310/ATMP.2007.v11.n6.a3
| arxiv = hep-th/0610241 | arxiv = hep-th/0610241
| s2cid = 9042911 }}
}}
</ref> and under an additional assumption, known as the "big desert" hypothesis, computations were carried out to predict the ] mass around 170 ] and postdict the ] mass. </ref> and under an additional assumption, known as the "big desert" hypothesis, computations were carried out to predict the ] mass around 170 ] and postdict the ] mass.


In August 2008, ] experiments In August 2008, ] experiments<ref name="arxiv:0808.0534">
{{cite book
<ref name="arxiv:0808.0534">
{{cite journal | title = Combined CDF and D0 Upper Limits on Standard Model Higgs Boson Production at High Mass (155−200−GeV/c2)(155-200-GeV/c^{2)}(155−200−GeV/c2) with 3 fb−1fb^{-1}fb−1 of Data | chapter = Combined CDF and DØ Upper Limits on Standard Model Higgs Boson Production at High Mass (155–200 GeV/''c''<sup>2</sup>) with 3 fb<sup>−1</sup> of data
| author = CDF and D0 Collaborations and Tevatron New Phenomena Higgs Working Group | author = CDF and D0 Collaborations and Tevatron New Phenomena Higgs Working Group
| journal = Proceedings, 34th International Conference on High Energy Physics (ICHEP 2008) | title = Proceedings, 34th International Conference on High Energy Physics
| year = 2008 | year = 2008
| arxiv = 0808.0534 | arxiv = 0808.0534
⚫ }}</ref> excluded a Higgs mass of 158 to 175 GeV at the 95% confidence level. Alain Connes acknowledged on a blog about non-commutative geometry that the prediction about the Higgs mass was invalidated.<ref>
}}
{{cite web
</ref>
excluded a Higgs mass of 158 to 175 GeV at the 95% confidence level.
⚫ ] acknowledged on a blog about non-commutative geometry that the prediction about the Higgs mass was falsified
<ref>
{{cite_web
| title = Irony | title = Irony
| accessdate=4 August 2008 | date=4 August 2008
| access-date=4 August 2008
| url = http://noncommutativegeometry.blogspot.com/2008/08/irony.html | url = http://noncommutativegeometry.blogspot.com/2008/08/irony.html
⚫ }}</ref> In July 2012, CERN announced the discovery of the ] with a mass around 125 GeV/''c''<sup>2</sup>.
}}</ref>.
⚫ In July 2012, CERN announced the discovery of the ] with a mass around 125 Gev.


A proposal to address the problem of the Higgs mass was published by ] and ] in 2012 A proposal to address the problem of the Higgs mass was published by ] and Alain Connes in 2012
<ref name="10.1007/JHEP09(2012)104"/> by taking into account a real scalar field that was already present in the model but was neglected in previous analysis. <ref name="10.1007/JHEP09(2012)104"/> by taking into account a real scalar field that was already present in the model but was neglected in previous analysis.
Another solution to the Higgs mass problem was put forward by Christopher Estrada and ] by studying renormalization group flow in presence of gravitational correction terms Another solution to the Higgs mass problem was put forward by Christopher Estrada and ] by studying renormalization group flow in presence of gravitational correction terms.<ref name="10.1142/S0219887813500369">
<ref name="10.1142/S0219887813500369">
{{cite journal | title = Asymptotic safety, hypergeometric functions, and the Higgs mass in spectral action models {{cite journal | title = Asymptotic safety, hypergeometric functions, and the Higgs mass in spectral action models
| last1 = Estrada | first1 =Christopher | last1 = Estrada | first1 =Christopher
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| number = 7 | number = 7
| year = 2013 | year = 2013
| doi = 10.1142/S0219887813500369 | pages = 1350036–68 | doi = 10.1142/S0219887813500369
| arxiv = 1208.5023 | arxiv = 1208.5023
| bibcode = 2013IJGMM..1050036E | s2cid = 215930 }}
}}
</ref>. </ref>


==See also== ==See also==
*] * ]
*] * ]
* ]
*] * ]


==Notes== ==Notes==
{{Reflist}}<!--added under references heading by script-assisted edit--> {{Reflist}}<!--added under references heading by script-assisted edit-->


== References == ==References==
* ] (1994) '''' Academic Press. {{ISBN|0-12-185860-X}}. * {{cite book |last1=Connes |first1=Alain |author-link=Alain Connes |year=1994 |url=http://www.alainconnes.org/docs/book94bigpdf.pdf |title=Noncommutative Geometry |publisher=Academic Press |isbn=0-12-185860-X}}
* {{cite journal |last1=Connes |first1=Alain |author-mask=1 |year=1995 |title=Noncommutative geometry and reality |journal=Journal of Mathematical Physics |volume=36 |issue=11 |pages=6194–6231|doi=10.1063/1.531241 |bibcode=1995JMP....36.6194C |url=https://cds.cern.ch/record/285273 }}
* -------- (1995) "Noncommutative geometry and reality," ''J. Math. Phys.'' 36: 6194.
* -------- (1996) "," ''Comm. Math. Phys.'' 155: 109. * {{cite journal |arxiv=hep-th/9603053 |doi=10.1007/BF02506388 |title=Gravity coupled with matter and the foundation of non-commutative geometry |year=1996 |last1=Connes |first1=Alain |author-mask=1 |journal=Communications in Mathematical Physics |volume=182 |issue=1 |pages=155–176 |bibcode=1996CMaPh.182..155C |s2cid=8499894}}
* -------- (2006) "," * {{cite web |last1=Connes |first1=Alain |author-mask=1 |year=2006 |url=http://www.alainconnes.org/docs/einsymp.pdf |title=Noncommutative geometry and physics}}
* -------- and ], '''' American Mathematical Society (2007). * {{cite book |last1=Connes |first1=Alain |author-mask=1 |last2=Marcolli |first2=Matilde |author2-link=Matilde Marcolli |year=2007 |url=http://www.alainconnes.org/en/downloads.php |title=Noncommutative Geometry: Quantum Fields and Motives |publisher=American Mathematical Society}}
* {{cite journal |arxiv=hep-th/9606001 |doi=10.1007/s002200050126 |title=The Spectral Action Principle |year=1997 |last1=Chamseddine |first1=Ali H. |last2=Connes |first2=Alain |journal=Communications in Mathematical Physics |volume=186 |issue=3 |pages=731–750 |bibcode=1997CMaPh.186..731C |s2cid=12292414}}
* Chamseddine, A., A. Connes (1996) "," ''Comm. Math. Phys.'' 182: 155.
* {{cite journal |arxiv=hep-th/0610241 |doi=10.4310/ATMP.2007.v11.n6.a3 |title=Gravity and the standard model with neutrino mixing |year=2007 |last1=Chamseddine |first1=Ali H. |last2=Connes |first2=Alain |last3=Marcolli |first3=Matilde |journal=Advances in Theoretical and Mathematical Physics |volume=11 |issue=6 |pages=991–1089 |s2cid=9042911}}
* Chamseddine, A., A. Connes, ] (2007) "," ''Adv. Theor. Math. Phys.'' 11: 991.
* Jureit, Jan-H., Thomas Krajewski, Thomas Schücker, and Christoph A. Stephan (2007) "," ''Acta Phys. Polon.'' B38: 3181-3202. * {{cite journal |arxiv=0705.0489 |last1=Jureit |first1=Jan-H. |last2=Krajewski |first2=Thomas |last3=Schucker |first3=Thomas |last4=Stephan |first4=Christoph A. |title=On the noncommutative standard model |journal=Acta Phys. Polon. B |year=2007 |volume=38 |issue=10 |pages=3181–3202 |bibcode=2007AcPPB..38.3181J}}
* {{cite book |doi=10.1007/978-3-540-31532-2_6 | arxiv=hep-th/0111236 | last1=Schucker | first1=Thomas | title=Topology and Geometry in Physics | chapter=Forces from Connes' Geometry | series=Lecture Notes in Physics | year=2005 | volume=659 | pages=285–350 | bibcode=2005LNP...659..285S| isbn=978-3-540-23125-7 | s2cid=16354019 }}
*Schücker, Thomas (2005) '''' Lecture Notes in Physics 659, Springer.


==External links== ==External links==
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{{DEFAULTSORT:Noncommutative Standard Model}} {{DEFAULTSORT:Noncommutative Standard Model}}
] ]
]

Latest revision as of 18:24, 23 December 2023

In theoretical particle physics, the non-commutative Standard Model (best known as Spectral Standard Model ), is a model based on noncommutative geometry that unifies a modified form of general relativity with the Standard Model (extended with right-handed neutrinos).

The model postulates that space-time is the product of a 4-dimensional compact spin manifold M {\displaystyle {\mathcal {M}}} by a finite space F {\displaystyle {\mathcal {F}}} . The full Lagrangian (in Euclidean signature) of the Standard model minimally coupled to gravity is obtained as pure gravity over that product space. It is therefore close in spirit to Kaluza–Klein theory but without the problem of massive tower of states.

The parameters of the model live at unification scale and physical predictions are obtained by running the parameters down through renormalization.

It is worth stressing that it is more than a simple reformation of the Standard Model. For example, the scalar sector and the fermions representations are more constrained than in effective field theory.

Motivation

Following ideas from Kaluza–Klein and Albert Einstein, the spectral approach seeks unification by expressing all forces as pure gravity on a space X {\displaystyle {\mathcal {X}}} .

The group of invariance of such a space should combine the group of invariance of general relativity Diff ( M ) {\displaystyle {\text{Diff}}({\mathcal {M}})} with G = Map ( M , G ) {\displaystyle {\mathcal {G}}={\text{Map}}({\mathcal {M}},G)} , the group of maps from M {\displaystyle {\mathcal {M}}} to the standard model gauge group G = S U ( 3 ) × S U ( 2 ) × U ( 1 ) {\displaystyle G=SU(3)\times SU(2)\times U(1)} .

Diff ( M ) {\displaystyle {\text{Diff}}({\mathcal {M}})} acts on G {\displaystyle {\mathcal {G}}} by permutations and the full group of symmetries of X {\displaystyle {\mathcal {X}}} is the semi-direct product: Diff ( X ) = G ⋊ Diff ( M ) {\displaystyle {\text{Diff}}({\mathcal {X}})={\mathcal {G}}\rtimes {\text{Diff}}({\mathcal {M}})}

Note that the group of invariance of X {\displaystyle {\mathcal {X}}} is not a simple group as it always contains the normal subgroup G {\displaystyle {\mathcal {G}}} . It was proved by Mather and Thurston that for ordinary (commutative) manifolds, the connected component of the identity in Diff ( M ) {\displaystyle {\text{Diff}}({\mathcal {M}})} is always a simple group, therefore no ordinary manifold can have this semi-direct product structure.

It is nevertheless possible to find such a space by enlarging the notion of space.

In noncommutative geometry, spaces are specified in algebraic terms. The algebraic object corresponding to a diffeomorphism is the automorphism of the algebra of coordinates. If the algebra is taken non-commutative it has trivial automorphisms (so-called inner automorphisms). These inner automorphisms form a normal subgroup of the group of automorphisms and provide the correct group structure.

Picking different algebras then give rise to different symmetries. The Spectral Standard Model takes as input the algebra A = C ∞ ( M ) ⊗ A F {\displaystyle A=C^{\infty }(M)\otimes A_{F}} where C ∞ ( M ) {\displaystyle C^{\infty }(M)} is the algebra of differentiable functions encoding the 4-dimensional manifold and A F = C ⊕ H ⊕ M 3 ( C ) {\displaystyle A_{F}=\mathbb {C} \oplus \mathbb {H} \oplus M_{3}(\mathbb {C} )} is a finite dimensional algebra encoding the symmetries of the standard model.

History

First ideas to use noncommutative geometry to particle physics appeared in 1988-89, and were formalized a couple of years later by Alain Connes and John Lott in what is known as the Connes-Lott model . The Connes-Lott model did not incorporate the gravitational field.

In 1997, Ali Chamseddine and Alain Connes published a new action principle, the Spectral Action, that made possible to incorporate the gravitational field into the model. Nevertheless, it was quickly noted that the model suffered from the notorious fermion-doubling problem (quadrupling of the fermions) and required neutrinos to be massless. One year later, experiments in Super-Kamiokande and Sudbury Neutrino Observatory began to show that solar and atmospheric neutrinos change flavors and therefore are massive, ruling out the Spectral Standard Model.

Only in 2006 a solution to the latter problem was proposed, independently by John W. Barrett and Alain Connes, almost at the same time. They show that massive neutrinos can be incorporated into the model by disentangling the KO-dimension (which is defined modulo 8) from the metric dimension (which is zero) for the finite space. By setting the KO-dimension to be 6, not only massive neutrinos were possible, but the see-saw mechanism was imposed by the formalism and the fermion doubling problem was also addressed.

The new version of the model was studied in and under an additional assumption, known as the "big desert" hypothesis, computations were carried out to predict the Higgs boson mass around 170 GeV and postdict the Top quark mass.

In August 2008, Tevatron experiments excluded a Higgs mass of 158 to 175 GeV at the 95% confidence level. Alain Connes acknowledged on a blog about non-commutative geometry that the prediction about the Higgs mass was invalidated. In July 2012, CERN announced the discovery of the Higgs boson with a mass around 125 GeV/c.

A proposal to address the problem of the Higgs mass was published by Ali Chamseddine and Alain Connes in 2012 by taking into account a real scalar field that was already present in the model but was neglected in previous analysis. Another solution to the Higgs mass problem was put forward by Christopher Estrada and Matilde Marcolli by studying renormalization group flow in presence of gravitational correction terms.

See also

Notes

  1. ^ Chamseddine, A.H.; Connes, A. (2012). "Resilience of the Spectral Standard Model". Journal of High Energy Physics. 2012 (9): 104. arXiv:1208.1030. Bibcode:2012JHEP...09..104C. doi:10.1007/JHEP09(2012)104. S2CID 119254948.
  2. Chamseddine, A.H.; Connes, A.; van Suijlekom, W. D. (2013). "Beyond the Spectral Standard Model: Emergence of Pati-Salam Unification". Journal of High Energy Physics. 2013 (11): 132. arXiv:1304.8050. Bibcode:2013JHEP...11..132C. doi:10.1007/JHEP11(2013)132. S2CID 18044831.
  3. Mather, John N. (1974). "Simplicity of certain groups of diffeomorphisms". Bulletin of the American Mathematical Society. 80 (2): 271–273. doi:10.1090/S0002-9904-1974-13456-7.
  4. Thurston, William (1974). "Foliations and groups of diffeomorphisms". Bulletin of the American Mathematical Society. 80 (2): 304–307. doi:10.1090/S0002-9904-1974-13475-0.
  5. Connes, Alain (1990). "Essay on physics and noncommutative geometry". The Interface of Mathematics and Particle Physics (Oxford, 1988). Inst. Math. Appl. Conf. Ser., New Ser. Vol. 24. New York: Oxford University Press. pp. 9–48.
  6. Dubois-Violette, Michel (1988). "Dérivations et calcul différentiel non commutatif". Comptes Rendus de l'Académie des Sciences, Série I (307): 403–408.
  7. Dubois-Violette, Michel; Kerner, Richard; Madore, John (1989). "Classical bosons in a non-commutative geometry". Classical and Quantum Gravity. 6 (11): 1709. Bibcode:1989CQGra...6.1709D. doi:10.1088/0264-9381/6/11/023. S2CID 250880966.
  8. Dubois-Violette, Michel; Kerner, Richard; Madore, John (1989). "Gauge bosons in a noncommutative geometry". Physics Letters B. 217 (4): 495–488. Bibcode:1989PhLB..217..485D. doi:10.1016/0370-2693(89)90083-X.
  9. Dubois-Violette, Michel; Kerner, Richard; Madore, John (1989). "Noncommutative differential geometry and new models of gauge theory". Journal of Mathematical Physics. 323 (31): 495–488. doi:10.1063/1.528917.
  10. Connes, Alain; Lott, John (1991). "Particle models and noncommutative geometry". Nuclear Physics B - Proceedings Supplements. 18 (2): 29–47. Bibcode:1991NuPhS..18...29C. doi:10.1016/0920-5632(91)90120-4. hdl:2027.42/29524.
  11. Chamseddine, Ali H.; Connes, Alain (1997). "The Spectral Action Principle". Communications in Mathematical Physics. 186 (3): 731–750. arXiv:hep-th/9606001. Bibcode:1997CMaPh.186..731C. doi:10.1007/s002200050126. S2CID 12292414.
  12. Lizzi, Fedele; Mangano, Gianpiero; Miele, Gennaro; Sparano, Giovanni (1997). "Fermion Hilbert Space and Fermion Doubling in the Noncommutative Geometry Approach to Gauge Theories". Physical Review D. 55 (10): 6357–6366. arXiv:hep-th/9610035. Bibcode:1997PhRvD..55.6357L. doi:10.1103/PhysRevD.55.6357. S2CID 14692679.
  13. Gracia-Bondía, Jose M.; Iochum, Bruno; Schücker, Thomas (1998). "The standard model in noncommutative geometry and fermion doubling". Physical Review B. 416 (1–2): 123–128. arXiv:hep-th/9709145. Bibcode:1998PhLB..416..123G. doi:10.1016/S0370-2693(97)01310-5. S2CID 15557600.
  14. Barrett, John W. (2007). "A Lorentzian version of the non-commutative geometry of the standard model of particle physics". Journal of Mathematical Physics. 48 (1): 012303. arXiv:hep-th/0608221. Bibcode:2007JMP....48a2303B. doi:10.1063/1.2408400. S2CID 11511575.
  15. Connes, Alain (2006). "Noncommutative Geometry and the standard model with neutrino mixing". Journal of High Energy Physics. 2006 (11): 081. arXiv:hep-th/0608226. Bibcode:2006JHEP...11..081C. doi:10.1088/1126-6708/2006/11/081. S2CID 14419757.
  16. Chamseddine, Ali H.; Connes, Alain; Marcolli, Matilde (2007). "Gravity and the standard model with neutrino mixing". Advances in Theoretical and Mathematical Physics. 11 (6): 991–1089. arXiv:hep-th/0610241. doi:10.4310/ATMP.2007.v11.n6.a3. S2CID 9042911.
  17. CDF and D0 Collaborations and Tevatron New Phenomena Higgs Working Group (2008). "Combined CDF and DØ Upper Limits on Standard Model Higgs Boson Production at High Mass (155–200 GeV/c) with 3 fb of data". Proceedings, 34th International Conference on High Energy Physics. arXiv:0808.0534.{{cite book}}: CS1 maint: numeric names: authors list (link)
  18. "Irony". 4 August 2008. Retrieved 4 August 2008.
  19. Estrada, Christopher; Marcolli, Matilde (2013). "Asymptotic safety, hypergeometric functions, and the Higgs mass in spectral action models". International Journal of Geometric Methods in Modern Physics. 10 (7): 1350036–68. arXiv:1208.5023. Bibcode:2013IJGMM..1050036E. doi:10.1142/S0219887813500369. S2CID 215930.

References

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