Space, Matter and Interactions in a Quantum Early Universe. Part II: Superalgebras and Vertex Algebras

In our investigation on quantum gravity, we introduce an infinite dimensional complex Lie algebra gu that extends e9. It is defined through a symmetric Cartan matrix of a rank 12 Borcherds algebra. We turn gu into a Lie superalgebra sgu with no superpartners, in order to comply with the Pauli exclusion principle. There is a natural action of the Poincaré group on sgu, which is an automorphism in the massive sector. We introduce a mechanism for scattering that includes decays as particular resonant scattering. Finally, we complete the model by merging the local sgu into a vertex-type algebra.

Cluster Structures on Double Bott–Samelson Cells

Let $\mathsf {C}$ be a symmetrisable generalised Cartan matrix. We introduce four different versions of double Bott–Samelson cells for every pair of positive braids in the generalised braid group associated to $\mathsf {C}$ . We prove that the decorated double Bott–Samelson cells are smooth affine varieties, whose coordinate rings are naturally isomorphic to upper cluster algebras. We explicitly describe the Donaldson–Thomas transformations on double Bott–Samelson cells and prove that they are cluster transformations. As an application, we complete the proof of the Fock–Goncharov duality conjecture in these cases. We discover a periodicity phenomenon of the Donaldson–Thomas transformations on a family of double Bott–Samelson cells. We give a (rather simple) geometric proof of Zamolodchikov’s periodicity conjecture in the cases of $\Delta \square \mathrm {A}_r$ . When $\mathsf {C}$ is of type $\mathrm {A}$ , the double Bott–Samelson cells are isomorphic to Shende–Treumann–Zaslow’s moduli spaces of microlocal rank-1 constructible sheaves associated to Legendrian links. By counting their $\mathbb {F}_q$ -points we obtain rational functions that are Legendrian link invariants.

The planar limit of $$ \mathcal{N} $$ = 2 superconformal quiver theories

We compute the planar limit of both the free energy and the expectation value of the 1/2 BPS wilson loop for four dimensional $$ \mathcal{N} $$ N = 2 superconformal quiver theories, with a product of SU(N)s as gauge group and hi-fundamental matter. Supersymmetric localization reduces the problem to a multi-matrix model, that we rewrite in the zero­ instanton sector as an effective action involving an infinite number of double-trace terms, determined by the relevant extended Cartan matrix. We find that the results, as in the case of $$ \mathcal{N} $$ N = 2 SCFTs with a simple gauge group, can be written as sums over tree graphs. For the $$ \hat{A_1} $$ A 1 ̂ case, we find that the contribution of each tree can be interpreted as the partition function of a generalized Ising model defined on the tree; we conjecture that the partition functions of these models defined on trees satisfy the Lee-Yang property, i.e. all their zeros lie on the unit circle.

On the structure of Kac–Moody algebras

Let A be a symmetrisable generalised Cartan matrix, and let $\mathfrak {g}(A)$ be the corresponding Kac–Moody algebra. In this paper, we address the following fundamental question on the structure of $\mathfrak {g}(A)$ : given two homogeneous elements $x,y\in \mathfrak {g}(A)$ , when is their bracket $[x,y]$ a nonzero element? As an application of our results, we give a description of the solvable and nilpotent graded subalgebras of $\mathfrak {g}(A)$ .

Duality Identities for Moduli Functions of Generalized Melvin Solutions Related to Classical Lie Algebras of Rank 4

We consider generalized Melvin-like solutions associated with nonexceptional Lie algebras of rank 4 (namely, A4, B4, C4, and D4) corresponding to certain internal symmetries of the solutions. The system under consideration is a static cylindrically symmetric gravitational configuration in D dimensions in presence of four Abelian 2-forms and four scalar fields. The solution is governed by four moduli functions Hs(z) (s=1,…,4) of squared radial coordinate z=ρ2 obeying four differential equations of the Toda chain type. These functions turn out to be polynomials of powers (n1,n2,n3,n4)=(4,6,6,4),(8,14,18,10),(7,12,15,16),(6,10,6,6) for Lie algebras A4, B4, C4, and D4, respectively. The asymptotic behaviour for the polynomials at large distances is governed by some integer-valued 4×4 matrix ν connected in a certain way with the inverse Cartan matrix of the Lie algebra and (in A4 case) the matrix representing a generator of the Z2-group of symmetry of the Dynkin diagram. The symmetry properties and duality identities for polynomials are obtained, as well as asymptotic relations for solutions at large distances. We also calculate 2-form flux integrals over 2-dimensional discs and corresponding Wilson loop factors over their boundaries.

On generalized Melvin solutions for Lie algebras of rank 3

Generalized Melvin solutions for rank-[Formula: see text] Lie algebras [Formula: see text], [Formula: see text] and [Formula: see text] are considered. Any solution contains metric, three Abelian 2-forms and three scalar fields. It is governed by three moduli functions [Formula: see text] ([Formula: see text] and [Formula: see text] is a radial variable), obeying three differential equations with certain boundary conditions imposed. These functions are polynomials with powers [Formula: see text] for Lie algebras [Formula: see text], [Formula: see text], [Formula: see text], respectively. The solutions depend upon integration constants [Formula: see text]. The power-law asymptotic relations for polynomials at large [Formula: see text] are governed by integer-valued [Formula: see text] matrix [Formula: see text], which coincides with twice the inverse Cartan matrix [Formula: see text] for Lie algebras [Formula: see text] and [Formula: see text], while in the [Formula: see text]-case [Formula: see text], where [Formula: see text] is the identity matrix and [Formula: see text] is a permutation matrix, corresponding to a generator of the [Formula: see text]-group of symmetry of the Dynkin diagram. The duality identities for polynomials and asymptotic relations for solutions at large distances are obtained. Two-form flux integrals over a two-dimensional disc of radius [Formula: see text] and corresponding Wilson loop factors over a circle of radius [Formula: see text] are presented.