UNIST — summer workshop 2026
dimer models · elliptic gamma functions
Benjamin Suzzoni
Department of Mathematical Sciences, UNIST
Chapter 1
from the conformal algebra to elliptic gamma integrals
The conformal group of \(\mathbb{R}^{1,3}\) is \(SO(2,4)\).
| translations \(P_\mu\) | \(4\) |
| Lorentz \(M_{\mu\nu}\) | \(6\) |
| dilatation \(D\) | \(1\) |
| special conformal \(K_\mu\) | \(4\) |
| Total | 15 |
\[ \begin{aligned}\\ [D,P_\mu] &= P_\mu\\ [D,K_\mu] &= -K_\mu\\ [M_{\mu\nu},P_\rho] &= \eta_{\nu\rho}P_\mu-\eta_{\mu\rho}P_\nu\\ [M_{\mu\nu},K_\rho] &= \eta_{\nu\rho}K_\mu-\eta_{\mu\rho}K_\nu\\ [K_\mu,P_\nu] &= 2\eta_{\mu\nu}D-2M_{\mu\nu}\\ \end{aligned} \]
In \(d=4\), \(\;\mathfrak{so}(2,4)\cong\mathfrak{su}(2,2)\). Radially quantizing on \(\mathbb{R}\times S^3\) turns \(D\) into the Hamiltonian \(E\); the maximal compact subalgebra \(\mathfrak{u}(1)_E\oplus\mathfrak{su}(2)_1\oplus\mathfrak{su}(2)_2\) supplies the labels \((E;j_1,j_2)\), with \(\mathrm{Spin}(4)=SU(2)_1\times SU(2)_2\) the isometry of \(S^3\).
Adding fermionic generators to \(\mathfrak{so}(2,4)\) and an abelian \(\mathfrak{u}(1)_R\) gives \(\mathfrak{su}(2,2|1)\), of superdimension \((16|8)\):
| conformal \(\;\mathfrak{so}(2,4)\) | 15 |
| R-symmetry \(\;R\) | 1 |
| Poincaré \(\;Q_\alpha,\ \bar Q_{\dot\alpha}\) (Q-susy) | 4 |
| conformal \(\;S^\alpha,\ \bar S^{\dot\alpha}\) (S-susy) | 4 |
| Total | 16 |
\( Q^\dagger{}^\alpha=S^\alpha\) and \(\bar Q^\dagger{}^{\dot\alpha} =\bar S^{\dot\alpha}\): four real supercharges of each type.
Note: \(\alpha\in\{+,-\}\) and \(\dot\alpha\in\{\dot{+},\dot{-}\}\)
Introduce new (anti)commutators to close the conformal algebra:
\[ \begin{aligned} \{Q_\alpha,\bar Q_{\dot\alpha}\} &= 2\sigma^\mu_{\alpha\dot\alpha}P_\mu\,, &\qquad \{\bar S^{\dot\alpha},S^{\alpha}\} &= 2\bar\sigma_\mu^{\dot\alpha\alpha}K^\mu\,,\\ [D,Q_\alpha] &= \tfrac12 Q_\alpha\,, & [D,S^\alpha] &= -\tfrac12 S^\alpha\,,\\ [R,Q_\alpha] &= -Q_\alpha\,, & [R,\bar Q_{\dot\alpha}] &= \bar Q_{\dot\alpha}\,, \end{aligned} \]
\[ \{Q_\alpha,S^{\beta}\}\;=\;4M_\alpha{}^{\beta} +2\delta_\alpha^\beta\big(D+\tfrac32 R\big)\,. \]
Pick a Poincaré supercharge \(\mathcal{Q}\equiv\bar{Q}_{\dot -}\) and set \(\bar M_{\dot -}{}^{\dot -}=-j_2\),
\[ \delta \;:=\; \tfrac12 \{\mathcal{Q},\mathcal{Q}^\dagger\}\;=\;E-2j_2-\tfrac32 R\;\ge\;0\,. \]
So-called short multiplets are annihilated by \(\mathcal{Q}\).
Summing over all operators, \(\ \mathrm{Tr}_{\mathcal{H}}\,e^{-\beta \delta}\), gives a partition function that
We want instead a rigid count — one that cannot change under a deformation preserving the supercharge.
\[ \mathcal{I}_W \;=\; \mathrm{Tr}_{\mathcal{H}}\Big[(-1)^F e^{-\beta \delta}\Big]\,. \]
With \(\tfrac12\{\mathcal{Q},\mathcal{Q}^\dagger\}=\delta\), every state of \(\delta>0\) sits in a two-dimensional multiplet \(\{|\psi\rangle, \mathcal{Q}|\psi\rangle\}\) of opposite fermion number: the pair cancels in the trace. Only \(\delta=0\) states survive, so \(\mathcal{I}_W\) is \(\beta\)-independent and deformation-invariant.
For an SCFT we refine this: grade the trace by every charge that commutes with the chosen supercharge, not just by \((-1)^F\). The result still only counts \(\delta=0\) states — but now it resolves them.
Note: \((-1)^F\;\text{Boson}=\text{Boson}\) and \((-1)^F\;\text{Fermion}=-\text{Fermion}\)
Radially quantizing on \(\mathbb{R}\times S^3\), states carry \(\big(E;j_1,j_2;R\big)\) and, with \(\mathcal{Q}=\bar Q_{\dot -}\), \(\ \delta=\tfrac12\{\mathcal{Q},\mathcal{Q}^\dagger\}=E-2j_2-\tfrac32 R\ge 0\). The superconformal index is the graded trace
\[ \mathcal{I}(p,q;\vec{v}) \;=\; \mathrm{Tr}_{\mathcal{H}(S^3)}\Big[(-1)^F\,p^{\,j_1+j_2+R/2}\, q^{\,j_2-j_1+R/2}\prod_a v_a^{\,Q_a}\Big]\,, \]
where \(v_a\) are fugacities for the global (flavour) charges \(Q_a\) commuting with \(\mathcal{Q}\).
\(p,q\) are conjugate to combinations that commute with \(\mathcal{Q}\) since \(\mathcal{Q}\) carries \((j_1,j_2,R)=(0,-\tfrac12,1)\)
Every \(\delta>0\) state pairs with a partner of opposite \((-1)^F\) and identical \((p,q,\vec v)\) charges, obtained by acting with \(\mathcal{Q}\) or \(\mathcal{Q}^\dagger\). Those pairs cancel identically.
\(\mathcal{I}\) is protected: independent of exactly marginal couplings, computable at weak coupling, invariant along the RG flow.
Restrict the trace to the \(\mathcal{Q}\)-closed letters of one free multiplet, then plethystically exponentiate and project onto gauge invariants:
\[ i_\chi(p,q;R_\chi)=\frac{(pq)^{R_\chi/2}-(pq)^{1-R_\chi/2}}{(1-p)(1-q)}\,,\qquad i_V(p,q)=-\frac{p}{1-p}-\frac{q}{1-q}+\frac{2pq}{(1-p)(1-q)}\,, \] \[ \mathcal{I}=\int_G[dU]\ \mathrm{PE}\Big[i_V\,\chi_{\rm adj}(U)+\textstyle\sum_i i_\chi(p,q;R_i)\,\chi_{\mathcal{R}_i}(U,\vec v)\Big]\,,\qquad \Gamma(z;p,q)=\prod_{j,k\ge0}\frac{1-z^{-1}p^{j+1}q^{k+1}}{1-z\,p^{j}q^{k}}\,. \]
Bifundamental \(\square\bar\square\) of \(SU(N)^2\) with R-charge \(r\) — a product of elliptic gamma functions:
\[ \prod_{i,j=1}^{N}\Gamma\big(t^{3r}z_i/w_j;p,q\big) \]
\(t=(pq)^{1/6}\) and \(\{z_i\},\{w_j\}\) unimodular with \(\prod_k z_k=\prod_k w_k=1\) parametrize the two Cartan subalgebras.
Adjoint of \(SU(N)\) — a Haar measure times elliptic gamma functions:
\[ \begin{aligned} \oint\!\mu(z;p,q) &:= \frac{\kappa^{N-1}}{N!} \oint_{\mathbb{T}_{N-1}}\prod_{i=1}^{N-1}\frac{dz_i}{2\pi i z_i}\\ &\quad\times\prod_{1\le k<l\le N}\frac{1}{\Gamma(z_k/z_l,z_l/z_k;p,q)} \end{aligned} \]
\(\mathbb{T}_{N-1}\) is \(N-1\) unit circles taken counterclockwise, and \(\kappa=(p;p)_\infty(q;q)_\infty\) with \((a;b)_\infty=\prod_{k\ge0}(1-ab^k)\).
Assembling one measure per gauge node and one elliptic gamma per chiral field, the index of a toric quiver gauge theory is the elliptic hypergeometric integral
\[ \begin{aligned} \mathcal{I}(p,q\,|\,r_{ij}) &= \prod_{k=1}^{G}\left(\frac{\kappa^{N-1}}{N!} \oint_{\mathbb{T}_{N-1}}\prod_{i=1}^{N-1}\frac{dz^{(k)}_i}{2\pi i z^{(k)}_i} \prod_{1\le l<m\le N}\frac{1}{\Gamma(z^{(k)}_l/z^{(k)}_m,z^{(k)}_m/z^{(k)}_l;p,q)}\right)\\ &\quad\times\prod_{X_{ij}}\prod_{l,m=1}^{N}\Gamma\big(t^{3r_{ij}}z^{(i)}_l/z^{(j)}_m;p,q\big) \end{aligned} \]
Everything on the right-hand side is fixed by two pieces of combinatorial data. That is the whole point: two theories with the same quiver have indices of the same functional form, and can only differ through their \(r_{ij}\).
Chapter 2
D3-branes probing a toric Calabi–Yau, drawn on a torus
A quiver \(Q\) is a directed graph. Each node \(i\) carries a gauge group \(SU(N)_i\), and each arrow \(i\to j\) is a chiral multiplet \(X_{ij}\) in the bifundamental \((\square_i,\bar\square_j)\).
| field | \(SU(N)_1\) | \(SU(N)_2\) | \(SU(N)_3\) | \(SU(N)_4\) |
|---|---|---|---|---|
| \(A_i\ (i=1,2)\) | \(\square\) | \(\bar\square\) | \(\cdot\) | \(\cdot\) |
| \(B_p\ (p=1,2)\) | \(\cdot\) | \(\square\) | \(\bar\square\) | \(\cdot\) |
| \(C_j\ (j=1,2)\) | \(\cdot\) | \(\cdot\) | \(\square\) | \(\bar\square\) |
| \(D_q\ (q=1,2)\) | \(\bar\square\) | \(\cdot\) | \(\cdot\) | \(\square\) |
Anomaly cancellation forces \(\#\{\text{in}\}=\#\{\text{out}\}\) at every node.
Closing the loop: \(\;W_{F_0}=\epsilon^{ij}\epsilon^{pq}\,A_i B_p C_j D_q\).
The full \(4d\ \mathcal{N}=1\) Lagrangian is fixed by the quiver plus one holomorphic function:
\[ \begin{aligned} \mathcal{L} \;=\;& \int\! d^4\theta\sum_{X_{ij}}\bar X_{ij}\,e^{V_i}X_{ij}e^{-V_j}\\ &+\Big(\int\! d^2\theta\Big[\tfrac{1}{4g^2}\sum_k\mathrm{Tr}(\,\mathcal{W}^{\alpha}_k\mathcal{W}_{\alpha k}) +W(X)\Big]+\mathrm{c.c.}\Big) \end{aligned} \]
Each monomial of \(W\) is an oriented closed loop of the quiver, its gauge indices contracted around the loop,
\[ X_{i_1i_2}X_{i_2i_3}\cdots X_{i_ki_1}\,. \]
Toric condition. Every chiral multiplet appears in exactly two monomials — once with \(+\), once with \(-\).
The vacuum moduli space solves the \(F\)-terms \(\partial W/\partial X_{ij}=0\) together with the \(D\)-terms; for special abelian theories this mesonic moduli space \(\mathcal{M}_{\rm mes}\) is a toric Calabi–Yau 3-fold.
At the superconformal fixed point the R-charges obey, for every node \(k\) and every superpotential term \(W_a\),
\[ \sum_{X\,\in\,\partial k}\big(1-r_X\big)=2\,, \qquad \sum_{X\in W_a}r_X=2\,, \]
the first being the vanishing NSVZ beta function at node \(k\), the second exact marginality of \(W\). The residual family of solutions is fixed by a-maximization,
\[ a(R)=\tfrac{3}{32}\big(3\,\mathrm{Tr}R^3-\mathrm{Tr}R\big)\,, \]
after which chiral primaries have \(\Delta=\tfrac32 R\).
| gauge theory | brane tiling on \(T^2\) | |
|---|---|---|
| node — \(SU(N)_i\) | ⟷ | face (a \(2n\)-gon = \(n\) flavours) |
| arrow — \(X_{ij}\) | ⟷ | edge |
| term of \(W\), sign \(+\,/\,-\) | ⟷ | white / black vertex |
| toric condition | ⟷ | graph is bipartite |
Arrows circulate clockwise around white nodes, anticlockwise around black ones; on \(T^2\), \(\;F-E+V=0\).
Chapter 3
spider moves on the tiling, identities on the index
\(SU(N_c)\) with \(N_f\) flavours flows to the same IR fixed point as \(SU(N_f-N_c)\) with \(N_f\) flavours, a meson \(M\sim Q\widetilde Q\) and a coupling \(M\widetilde q q\).
| on the quiver | on the brane tiling | |
|---|---|---|
| node \(k\) with \(N_f=2N_c\) | ⟷ | quadrilateral face |
| reverse the arrows at \(k\) | ⟷ | square's corners change colour |
| mesons \(M_{ab}\sim X_{ak}X_{kb}\) | ⟷ | one new edge per corner |
| mass terms integrated out | ⟷ | 2-valent nodes contracted |
The dualized face is a quadrilateral again, as it must be: the dual node still has \(N_f=2N_c\).
\(H_{1,1,2,1}=H_{1,1,1,2}=\mathrm{PdP}_{5c}\)
Gauge group \(SU(N)^9\), and 42 toric phases in its duality tree.
Dualizing gauge node 9 — the highlighted quadrilateral face — takes phase \(2a\) to phase \(2b\) and back.
\(\mathcal{M}_{\rm mes}\) is unchanged: one geometry, many toric phases, organized into a duality tree.
Since \(\mathcal{I}\) is invariant along the flow, an IR duality becomes an identity between elliptic hypergeometric integrals (Dolan–Osborn).
Rains's theorem is the \(SU(N)\) identity. For the part of the index attached to one \(SU(N)\) node \(n\),
\[ I_n\big(\left\{\tfrac{t^{3r_{na}}}{z^{(a)}}\right\}_{a\leftarrow n},\{t^{3r_{bn}}z^{(b)}\}_{b\rightarrow n}\big) =\oint\!\mu(z^{(n)})\prod_{l,m=1}^{N}\Big(\prod_{a\leftarrow n}\Gamma\big(t^{3r_{na}} z^{(n)}_l/z^{(a)}_m\big)\prod_{b\rightarrow n}\Gamma\big(t^{3r_{bn}}z^{(b)}_l/z^{(n)}_m\big)\Big)\,, \]
\[ I_n\big(\left\{\tfrac{t^{3r_{na}}}{z^{(a)}}\right\}_{a\leftarrow n},\{t^{3r_{bn}}z^{(b)}\}_{b\rightarrow n}\big) =\prod_{l,m=1}^{N}\prod_{\substack{a\leftarrow n\\ b\rightarrow n}}\Gamma\big(t^{3(r_{na}+r_{bn})}z^{(b)}_l/z^{(a)}_m\big)\ \times\ I_n\big(\left\{\tfrac{t^{3(U-r_{bn})}}{z^{(b)}}\right\}_{b\rightarrow n},\{t^{3(T-r_{na})}z^{(a)}\}_{a\leftarrow n}\big) \]
with \(T=\sum_{a\leftarrow n}r_{na}\) and \(U=\sum_{b\rightarrow n}r_{bn}\). Integrating out a mass term is the inversion formula \(\Gamma(z;p,q)=1/\Gamma(pq/z;p,q)\).
Chapter 4
same quiver, different superpotential
Phases \(2a\) and \(2b\) are related by Seiberg duality on node 9. Overlaid on each tiling — one gauge node at the centre of every face — the two quivers are the same up to arrow reversal.
\(H_{1,1,2,1}\) — 9 gauge nodes, 42 toric phases, falling into five doublets and one triplet that share a common quiver.
Both have 9 faces, 19 edges and 10 vertices. Only the superpotential is different.
Two quiver-invariant duals have the same gauge group and the same matter, so their indices have identical functional form — the same measures, the same number of elliptic gammas. All that differs is the R-charge assignment. Equating them is a non-trivial identity:
\[ \mathcal{I}\big(p,q\,\big|\,\{r_{ij}\}\big)\;=\;\mathcal{I}\big(p,q\,\big|\,\{r'_{ij}\}\big) \]
For the doublet \(2a\)/\(2b\) of \(H_{1,1,2,1}\), the R-charges of ten fields are exchanged in pairs and the other nine are untouched:
| field | phase 2a | field | phase 2b | |
|---|---|---|---|---|
| \(r_{15}\) | \(R_3+R_6\) | ⟷ | \(r_{83}\) | \(R_1+R_3\) |
| \(r_{18}\) | \(R_2\) | ⟷ | \(r_{53}\) | \(R_5\) |
| \(r_{21}\) | \(R_1\) | ⟷ | \(r_{34}\) | \(R_6\) |
| \(r_{28}\) | \(R_5+R_6\) | ⟷ | \(r_{54}\) | \(R_1+R_2\) |
| \(r_{32}\) | \(R_2+R_4\) | ⟷ | \(r_{41}\) | \(R_4+R_5\) |
\(R_1,\dots,R_6\) are the R-charges of the six extremal GLSM fields (the corners of the toric diagram), with \(\sum_a R_a = 2\).
The set of R-charges is the same on both sides. This is not true in general. It is not a local move: it is tied to the global structure of the quiver, so it cannot be written as a local elliptic gamma identity.
A closed-form superconformal index for a non-trivial quiver gauge theory is still out of reach — but every exact identity we can write down is another constraint the answer has to satisfy.
Questions are always welcome — b.suzzoni@benterre.com