scholarly journals Current algebra formulation of quantum gravity and its application to cosmology

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Shotaro Shiba Funai ◽  
Hirotaka Sugawara
Keyword(s):  
Current Algebra ◽  
Early Stage ◽  
Gravity Theory ◽  
Accelerating Universe ◽  
Spin Connection ◽  
General Covariance ◽  
De Sitter ◽  
Tetrad Field ◽  
Poincaré Algebra ◽  
M Theory

Abstract Gravity theory based on current algebra is formulated. The gauge principle rather than general covariance combined with the equivalence principle plays a pivotal role in the formalism, and the latter principles are derived as a consequence of the theory. In this approach, it turns out that gauging the Poincaré algebra is not appropriate but gauging the $SO(N,M)$ algebra gives a consistent theory. This makes it possible to have anti-de Sitter and de Sitter space-time by adopting a relation between the spin connection and the tetrad field. The Einstein equation is part of our basic equation for gravity, which is written in terms of the spin connection. When this formalism is applied to the $E(11)$ algebra in which the three-form antisymmetric tensor is part of a gravity multiplet, we have a current algebra gravity theory based on M-theory in the sense that the internal group or the connection space representations of our model are those appearing in 11D supergravity. Moreover, when our formalism in its classical limit is applied to cosmology, by introducing conformal-like modes that connect the tetrad field/current and the spin connection field/current, we can obtain an accelerating universe in the manner of the “inflating” universe at its early stage.

scholarly journals Currents, charges and algebras in exceptional generalised geometry

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
David Osten
Keyword(s):  
Current Algebra ◽  
Hamiltonian Formulation ◽  
Building Blocks ◽  
Lie Derivative ◽  
Consistency Check ◽  
World Volume ◽  
Invariant Currents ◽  
Invariant Current ◽  
M Theory ◽  
A Current

Abstract A classical Ed(d)-invariant Hamiltonian formulation of world-volume theories of half-BPS p-branes in type IIb and eleven-dimensional supergravity is proposed, extending known results to d ≤ 6. It consists of a Hamiltonian, characterised by a generalised metric, and a current algebra constructed s.t. it reproduces the Ed(d) generalised Lie derivative. Ed(d)-covariance necessitates the introduction of so-called charges, specifying the type of p-brane and the choice of section. For p > 2, currents of p-branes are generically non- geometric due to the imposition of U-duality, e.g. the M5-currents contain coordinates associated to the M2-momentum.A derivation of the Ed(d)-invariant current algebra from a canonical Poisson structure is in general not possible. At most, one can derive a current algebra associated to para-Hermitian exceptional geometry.The membrane in the SL(5)-theory is studied in detail. It is shown that in a generalised frame the current algebra is twisted by the generalised fluxes. As a consistency check, the double dimensional reduction from membranes in M-theory to strings in type IIa string theory is performed. Many features generalise to p-branes in SL(p + 3) generalised geometries that form building blocks for the Ed(d)-invariant currents.

scholarly journals SUPERGRAVITY DESCRIPTION OF FIELD THEORIES ON CURVED MANIFOLDS AND A NO GO THEOREM

2001 ◽  
Vol 16 (05) ◽  
pp. 822-855 ◽  
Author(s):  
JUAN MALDACENA ◽  
CARLOS NUÑEZ
Keyword(s):  
Field Theory ◽  
Conformal Field Theory ◽  
Riemann Surface ◽  
Riemann Surfaces ◽  
Field Theories ◽  
De Sitter ◽  
Curved Manifolds ◽  
Conformal Field ◽  
Low Energies ◽  
M Theory

In the first part of this paper we find supergravity solutions corresponding to branes on worldvolumes of the form Rd×Σ where Σ is a Riemann surface. These theories arise when we wrap branes on holomorphic Riemann surfaces inside K3 or CY manifolds. In some cases the theory at low energies is a conformal field theory with two less dimensions. We find some non-singular supersymmetric compactifications of M-theory down to AdS5. We also propose a criterion for permissible singularities in supergravity solutions. In the second part of this paper, which can be read independently of the first, we show that there are no non-singular Randall-Sundrum or de-Sitter compactifications for large class of gravity theories.

scholarly journals Κατασκευή βαρυτικών μοντέλων ως θεωριών βαθμίδας σε μη μεταθετικούς χώρους

2019 ◽  
Author(s):  
Γεώργιος Μανωλάκος
Keyword(s):  
Spin Connection ◽  
De Sitter ◽  
Yang Mills ◽  
Chern Simons

Η βαρυτική αλληλεπίδραση στις τρεις και τέσσερις διαστάσεις περιγράφεται επιτυχώς από τη Γενική Θεωρία της Σχετικότητας του Einstein στις οποίες η βαρύτητα θεωρείται ως μία ιδιότητα του χωρόχρονου. Παρόλα αυτά, η περιγραφή της βαρυτικής αλληλεπίδρασης επιδέχεται μία εναλλακτική προσέγγιση, αυτήν της θεωρίας βαθμίδας των ομάδων συμμετριών των θεωρούμενων χωρόχρονων, στις οποίες τα πεδία βαθμίδας ταυτοποιούνται με το vielbein και το spin connection. Η βαρύτητα στις τρεις διαστάσεις είναι ακριβώς ισοδύναμη με μία θεωρία βαθμίδας τύπου Chern Simons της ομάδας ISO(1,2), ενώ αν περιλαμβάνεται η κοσμολογική σταθερά τότε οι αντίστοιχες ομάδες είναι οι SO(1,3) και SO(2,2), ανάλογα με το πρόσημό της. Η τετραδιάστατη περίπτωση είναι λίγο πιο περίπλοκη, μιας και αν θεωρήσουμε μία θεωρία βαθμίδας, παρά το γεγονός ότι οι μετασχηματισμοί των πεδίων και οι εκφράσεις των τανυστών καμπυλότητας προκύπτουν ως αναμένεται, υπάρχει ένα κώλυμα στο δυναμικό κομμάτι της θεωρίας, διότι δεν μπορεί να οριστεί με αυτό τον τρόπο κάποια δράση, η μορφή της οποίας να συμπίπτει με την Einstein-Hilbert. Ωστόσο, το παραπάνω πρόβλημα ξεπερνιέται θεωρώντας μία SO(1,4) αναλλοίωτη δράση με την ταυτόχρονη συμπερίληψη ενός βαθμωτού πεδίου στη θεμελιώδη αναπαράσταση. Το πεδίο αυτό επάγει την αυθόρμητη παραβίαση της συμμετρίας και οδηγεί στη ζητούμενη Einstein-Hilbert δράση. Επιπλέον, υπάρχει ένα παρόμοιο πρόγραμμα στο οποίο η βαρύτητα Weyl μεταφράζεται επιτυχώς ως μία θεωρία βαθμίδας της τετραδιάστατης σύμμορφης ομάδας, SO(2,4). Παρομοίως, στην περίπτωση αυτή, κάποιος ξεκινάει με μια δράση τύπου Yang-Mills και με την επιβολή συγκεκριμένων συνδέσμων, σπάει την επιπλέον συμμετρία, καταλήγωντας με μία θεωρία ταυτόσημη με αυτήν της βαρύτητας Weyl. Οι παραπάνω κατασκευές μπορούν να μεταφερθούν στο πλαίσιο της μη μεταθετικής γεωμετρίας. Πιο συγκεκριμένα, στην περιοχή υψηλών ενεργειών (κλίμακα Planck) η μεταθετικότητα των συντεταγμένων του χώρου μπορεί να θεωρηθεί ότι αίρεται, επομένως οι φυσικές θεωρίες στην περιοχή αυτήν πρέπει να τροποποιηθούν κατάλληλα. Αυτή είναι η ουσία των εργασιών που συνθέτουν την παρούσα διατριβή, δηλαδή η διερεύνηση της βαρυτικής αλληλεπίδρασης στο μη μεταθετικό πλαίσιο εργασίας. Αυτό επιτυγχάνεται συνδυάζοντας την πετυχημένη περιγραφή της βαρύτητας ως θεωρίας βαθμίδας στις τρεις και τέσσερις διαστάσεις με την καλώς ορισμένη κατασκευή θεωριών βαθμίδας σε μη μεταθετικούς χώρους, με αποτέλεσμα την κατασκευή βαρυτικών μοντέλων ως θεωριών βαθμίδας σε μη μεταθετικούς (ασαφείς) χώρους. Αρχικά, δουλέψαμε στην τρισδιάστατη περίπτωση, τόσο στην Lorentzian, όσο και στην Ευκλείδεια περίπτωση, χρησιμοποιώντας δύο ασαφείς χώρους, οι οποίοι ορίζονται ως φυλλοποιήσεις των τρισδιάστατων Minkowski και Ευκλείδειου χώρων από ασαφή υπερβολοειδή και ασαφείς σφαίρες, αντίστοιχα. Η κατασκευή των θεωριών βαθμίδας οδήγησε στην εξεύρεση των μετασχηματισμών των πεδίων βαθμίδας (vielbein και spin connection) και των εκφράσεων των τανυστών καμπυλότητας καθώς επίσης και στην δράση τύπου Chern-Simons, από την οποία εξάχθηκαν οι εξισώσεις κίνησης. Είναι αξιοσημείωτο ότι όλα τα αποτελέσματα ανάγονται σε αυτά της τρισδιάστατης θεωρίας της βαρύτητας του Einstein κατά την θεώρηση του μεταθετικού ορίου. Έπειτα, επικεντρωθήκαμε στην τετραδιάστατη περίπτωση στην οποία ο μη μεταθετικός χώρος που θεωρήσαμε ήταν η ασαφής εκδοχή του τετραδιάστατου χώρου de Sitter. Παρομοίως με την τρισδιάστατη περίπτωση, ακολουθώντας την καθιερωμένη διαδικασία κατασκευής θεωριών βαθμίδας σε μη μεταθετικούς χώρους, υπολογίζονται οι μετασχηματισμοί των πεδίων βαθμίδας και οι εκφράσεις των τανυστών καμπυλότητας καθώς και ορίζεται αρχικά μία δράση τύπου Yang-Mills, η συμμετρία της οποίας παραβιάζεται από την επιβολή κατάλληλων συνδέσμων. Τα αποτελέσματα και στην περίπτωση αυτή συνάδουν με αυτά της σύμμορφης βαρύτητας στο μεταθετικό όριο.

scholarly journals A CHERN–SIMONS E8 GAUGE THEORY OF GRAVITY IN D = 15, GRAND UNIFICATION AND GENERALIZED GRAVITY IN CLIFFORD SPACES

2007 ◽  
Vol 04 (08) ◽  
pp. 1239-1257 ◽  
Author(s):  
CARLOS CASTRO
Keyword(s):  
Gauge Theory ◽  
Grand Unification ◽  
De Sitter ◽  
Sitter Group ◽  
Yang Mills ◽  
Theory Of Gravity ◽  
M Theory ◽  
Chern Simons ◽  
Topological Part ◽  
Gauge Theory Of Gravity

A novel Chern–Simons E8 gauge theory of gravity in D = 15 based on an octicE8 invariant expression in D = 16 (recently constructed by Cederwall and Palmkvist) is developed. A grand unification model of gravity with the other forces is very plausible within the framework of a supersymmetric extension (to incorporate spacetime fermions) of this Chern–Simons E8 gauge theory. We review the construction showing why the ordinary 11D Chern–Simons gravity theory (based on the Anti de Sitter group) can be embedded into a Clifford-algebra valued gauge theory and that an E8 Yang–Mills field theory is a small sector of a Clifford (16) algebra gauge theory. An E8 gauge bundle formulation was instrumental in understanding the topological part of the 11-dim M-theory partition function. The nature of this 11-dim E8 gauge theory remains unknown. We hope that the Chern–Simons E8 gauge theory of gravity in D = 15 advanced in this work may shed some light into solving this problem after a dimensional reduction.

scholarly journals Exact Axially Symmetric Solution inf(T)Gravity Theory

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Gamal G. L. Nashed
Keyword(s):  
Vacuum Solution ◽  
Gravity Theory ◽  
Kerr Metric ◽  
Radial Coordinate ◽  
Lorentz Transformations ◽  
Axially Symmetric ◽  
Field Equations ◽  
Tetrad Field ◽  
Kerr Spacetime ◽  
Euler’S Angles

A general tetrad field with sixteen unknown functions is applied to the field equations off(T)gravity theory. An analytic vacuum solution is derived with two constants of integration and an angleΦthat depends on the angle coordinateϕand radial coordinater. The tetrad field of this solution is axially symmetric and the scalar torsion vanishes. We calculate the associated metric of the derived solution and show that it represents Kerr spacetime. Finally, we show that the derived solution can be described by two local Lorentz transformations in addition to a tetrad field that is the square root of the Kerr metric. One of these local Lorentz transformations is a special case of Euler’s angles and the other represents a boost when the rotation parameter vanishes.

scholarly journals NEW GEOMETRIC FORMALISM FOR GRAVITY EQUATION IN EMPTY SPACE

2005 ◽  
Vol 14 (06) ◽  
pp. 1009-1022 ◽  
Author(s):  
XIN-BING HUANG
Keyword(s):  
Differential Equations ◽  
Gauge Field ◽  
Empty Space ◽  
Space Time ◽  
Gravity Theory ◽  
Spin Connection ◽  
Square Root ◽  
Field Equations ◽  
Complex Spin ◽  
Set Up

In this paper, a complex daor field which can be regarded as the square root of space–time metric is proposed to represent gravity. The locally complexified geometry is set up, and the complex spin connection constructs a bridge between gravity and SU(1, 3) gauge field. Daor field equations in empty space are acquired, which are one-order differential equations and do not conflict with Einstein's gravity theory.

scholarly journals Current algebra formulation of M-theory based on E11 Kac–Moody algebra

2017 ◽  
Vol 32 (05) ◽  
pp. 1750024 ◽  
Author(s):  
Hirotaka Sugawara
Keyword(s):  
Current Algebra ◽  
Equations Of Motion ◽  
Internal Symmetry ◽  
Momentum Tensor ◽  
Moody Algebra ◽  
Finite Dimensional ◽  
The One ◽  
Quantum Equations ◽  
M Theory ◽  
Gravitino Field

Quantum M-theory is formulated using the current algebra technique. The current algebra is based on a Kac–Moody algebra rather than usual finite dimensional Lie algebra. Specifically, I study the [Formula: see text] Kac–Moody algebra that was shown recently[Formula: see text] to contain all the ingredients of M-theory. Both the internal symmetry and the external Lorentz symmetry can be realized inside [Formula: see text], so that, by constructing the current algebra of [Formula: see text], I obtain both internal gauge theory and gravity theory. The energy–momentum tensor is constructed as the bilinear form of the currents, yielding a system of quantum equations of motion of the currents/fields. Supersymmetry is incorporated in a natural way. The so-called “field-current identity” is built in and, for example, the gravitino field is itself a conserved supercurrent. One unanticipated outcome is that the quantum gravity equation is not identical to the one obtained from the Einstein–Hilbert action.

scholarly journals DE SITTER COSMOLOGY FROM GAUSS–BONNET DARK ENERGY WITH QUANTUM EFFECTS

2008 ◽  
Vol 17 (11) ◽  
pp. 2159-2170 ◽  
Author(s):  
EMILIO ELIZALDE ◽  
JOHN QUIROGA HURTADO ◽  
HÉCTOR IVÁN ARCOS
Keyword(s):  
Dark Energy ◽  
Correction Term ◽  
Quantum Effects ◽  
Classical Case ◽  
De Sitter ◽  
Quantum Anomaly ◽  
The Stability ◽  
M Theory ◽  
Friedmann Robertson Walker ◽  
Matter Fields

A Gauss–Bonnet dark energy model is considered. It is inspired by string/M-theory and also takes into account quantum contributions, which are introduced from a conformal quantum anomaly. The corresponding solutions for the Hubble rate, H, are studied starting from the Friedmann–Robertson–Walker equation. It is seen that, as a pure effect of the quantum contributions, a new solution for H exists in some region, which does not appear in the classical case. The behavior of all encountered solutions is studied with care, in particular the role played by the quantum correction term — which depends on the number of matter fields — in the stability of the solutions around its asymptotic value. It is argued that, contrary to what happens in the classical case, quantum effects remarkably lead to the realization of a de Sitter stage which corresponds to the inflation/dark energy stages, even for positive values of the f0 constant (coupling of the field with the Gauss–Bonnet invariant).

scholarly journals Non-relativistic limits and three-dimensional coadjoint Poincaré gravity

2020 ◽  
Vol 476 (2240) ◽  
pp. 20200106
Author(s):  
Eric Bergshoeff ◽  
Joaquim Gomis ◽  
Patricio Salgado-Rebolledo
Keyword(s):  
Three Dimensional ◽  
De Sitter ◽  
Poincaré Algebra ◽  
The Way

We show that a recently proposed action for three-dimensional non-relativistic gravity can be obtained by taking the limit of a relativistic Lagrangian that involves the coadjoint Poincaré algebra. We point out the similarity of our construction with the way that three-dimensional Galilei gravity and extended Bargmann gravity can be obtained by taking the limit of a relativistic Lagrangian that involves the Poincaré algebra. We extend our results to the anti-de Sitter case and we will see that there is a chiral decomposition at both the relativistic and non-relativistic level. We comment on possible further generalizations.

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