Properties of BLG model Gauge symmetry based on Lie 3-algebra Maximal SUSY (N=8) No arbitrary parameter except for structure constant Gauge field described by Chern-Simons Lagrangian (No propagating d.o.f) Lagrangian is defined only through structure constant (adjoint representation) BPS equation takes the form of Basu-Harvey
Study of A 4 model First example: A 4 -- SO(4) inv. algebra (BLG) cf. Kawamura Initial confusion: how many M2 branes ? Number of moduli: elements that satisfies One may take such generators as T 1, T 2 (moduli=2) If we add 1 for center of M2 branes, the number of M2 may be 3. This initial confusion was resolved by introducing Higgs-like mechanism (Mukhi and Papageorgakis) : number of M2 is 2 For level k theory, the moduli is conjectured to be (R 8 ) 2 /D 2k
III. Study of Lie 3 algebra Bandres, Lipstein, Schwarz Ho, Hou, Matsuo Papadopoulos Gauntlett, Gutowski Mendeiros, Figueroa-O’Farril, Mendez-Escobar Mendeiros, Figueroa-O’Farrill, Mendez-Escobar
NO GO theorem Other algebra? many studies FI h > 0 finite D anti-symmetric Only possible Lie 3-algebra is A 4 and its direct sum ! (NO GO THEOREM) HHM(1) Conjecture Papadopoulos Gauntlett & Gutowski
Escape from NO-GO theorem With milder condition, there exists other Lie 3-algebras negative/null norm generators infinite D Lorentzian BLG model M5 non anti-symmetric ABJM model (N=6 SUSY) Bagger-Lambert Ho-M, Ho-Imamura-M-Shiba
Lorentzian Lie 3-algebra Lie algebra + 1 extra generator cf. Awata, Li, Minic, Yoneya ‘99 Lie 3-algebra appear only on LHS center Invariant metric Killing form Lorentzian signature Further study: Mendeiros, Figueroa-O’Farril, Mendez-Escobar
Nambu-Poisson bracket FI anti-symmetric tensor It implies a very strong constraint on P !! Decomposability Nambu-Poisson bracket exists only in 3 dimensions Infinite dim. Lie 3-algebra
Non-antisymmetric 3-algebra To keep N=6 SUSY, we do not need antisymmetry 3-algebra Such 3-algebra can be realized by rectangle matrices where When n=m, BLG model based on this 3-algebra is ABJM model! with fundamental identity for f and invariance of metric h
Generic feature of Lorentzian system Equation of motion Symmetry transformation (SUSY, gauge transf.) The value of Y fields do not affect other fields: Y are irrelevant with dynamics X are free fields : Their VEV does not break symmetry of the system (like coupling const?)
More explicitly The bosonic part of the lagrangian becomes where
Treatment of ghost lagrangian Variation of We can treat them as classical fields! One can set without losing consistency of e.o.m. SUSY and Gauge symmetry can be kept After this L gh =0! No ghost in the theory
D2 action One can integrate A’ in the Lagrangian cf. Mukhi, Papageorgakis Higgs-like mechanism : X 10 is converted into d.o.f. of gauge fields Removal of ghosts was carried out by introducing extra gauge symmetry by Bandres-Lipstein-Schwarz ( ) and Gomis- Rodriguez-Gomez-Raamsdonk-Verlinde ( ).
M2 or D2 ? By dualizing diagonal part of U(N) gauge fields, one obtains 8 th extra dimensions which describe the motion of M2 in 11 th dimension. Moduli space: (R 8 ) N /S N which coincides with moduli of M2 The M2 limit corresponds to v ∞ : It implies that the coupling is infinitely large : So it may not be a practical description to study multiple M2 Recent study of the structure of the vacua of the mass deformed theory (Gomis et. al ) or membrane scattering (Verlinde, ) also imply that Lorentzian BLG model does not give a good description of multiple M2 branes. Therefore it would be more practical to regard Lorentzian BLG model as the description of D2 branes in the context of BLG
Definition of ABJM model Lagrangian (Component form from Benna-Klebanov-Klose-Smedback, Bagger-Lambert ) U(N)x U(N) gauge symmetry: Z A complex NxN matrices Chern-Simons term: level k + level (-k) N=6 SUSY (SU(4) R-symmetry: Rotation of Z A ) No freely adjustable parameters (except for N and k) 3-algebra NOT NEEDED
Structure of Moduli Orbifold projection breaks N=8 to N=6 for k>2 For k=1,2, we expect to have N=8 SUSY For N=2, it reduces to A 4 BLG model Origin of orbifold projection: quantization of CS term by gauge transformation
Brane construction IIB string NS5+D3+D5 system NS5 D3 : _ _ _6 _ _ _ NS5: _ _ _ _ D5 : _ _ _ _ 9 k D5 N D3 U(N)xU(N) gauge sym. N=2 SUSY Mass deformation NS5 D5 (1,k) 5 brane Generation of level k & (-k) CS term (1,k) 5 brane N=3 SUSY IIA theory T-duality D3 D2 NS5 KK monopole (1,k)5 KK monopole M-theory D2 M2 KK momentum C 4 /Z k background
Gravity dual M theory AdS/CFT: AdS 4 x S 7 S 7 : S 1 fibration over CP 3 level k theory: S 1 S 1 /Z k ‘t Hooft coupling : λ= N/k M theory description is valid for k 5 << N IIA description : λ =(R str ) 4 << 1, N<< k 5 IIA theory : AdS 4 x CP 3 Spectrum of SUGRA field coincides with chiral primary in field theory !
Integrable model Color singlet operator: IIB AdS 4 x S 5 IIA AdS 4 x CP 3 : integrability at two loops Spin chain Hamiltonian alternating spin system Osp(2,2|6) invariant Bethe ansats system
VI. Nambu bracket, M5 & Entropy law Ho-M Ho-Imamura-M-Shiba Park-Sochichiu Bandos-Townsend Chu-Ho-M-Shiba
:original membrane worldvolume :3 dim mfd where NP structure is defined M2 (3d) M5 (6d)
Gauge field bilocal in N? No! They appear only in the combination So what we need is, local field in 6d
Division of transverse space We put, Fields on M5 Self-dual two form after field redefinition
Gauge symmetry on M5 BLG gauge symmetry reduces to volume preserving diffeo of N
M5 Action Quadratic part (HM2, complete formula HIMS4) Lorentz covariant for X i and Ψ but non-covariant for b fields However, the e.o.m becomes covariant even for b fields self-dual two form fields on M5
Derivation of N 3/2 law Chu-Ho-M-Shiba Cut-off version of Nambu-Poisson bracket Truncate the Hilbert space to polynomials with degree ≤ N This 3-bracket still satisfies fundamental identity can define N=8 SUSY equation of motion Number of moduli: mutually commuting elements f, g, h: function of two variables, x 1 and x 2 Degree of freedom:
N 3/2 law is a universal feature of (quantum) 3- algebra system? Quantum Nambu bracket Cubic matrices (Awata et. al., Kawamura) Matrix realization (Curtright-Zachos) Fuzzy S 3 (Raamsdonk) Generalization of Moyal product Zariski Quantization (Dito et. al.) Open Membrane and noncommutative vortex string (Sasakura, Matsuo-Shibusa, Pioline) Intertwine M2 M5 by taking large N limit?
VII. Conclusion BLG model is a real breakthrough to understand M-theory It is the first realistic model where 3-algebra becomes the gauge symmetry (multiple) D2 and (single) M5 can be described within BLG framework There appeared a promising proposal (ABMJ) which would describe multiple M2 for large k
Future directions N 3/2 law was derived from cut-off version of Nambu-Poisson bracket but cut-off symmetry is not good enough ABJM model is good for k>>1 (string regime) but strong interaction makes it difficult to derive N 3/2 law for k=O(1) BLG model based on genuine 3-algebra (quantum Nambu bracket) would be necessary to describe M-theory regime of M2 brane Description of multiple M5 brane is totally missing yet!
Why 3-algebra is needed for M2? Gauge invariant operators: Two algebra Spin chain: string like object Three algebra Decomposition of S 2 ! Relation with 3d lattice gravity Ho-M. (‘07)