UNIST — summer workshop 2026

4d \(\mathcal{N}=1\) superconformal index identity
from quiver-invariant duality

dimer models  ·  elliptic gamma functions

Benjamin Suzzoni
Department of Mathematical Sciences, UNIST

Outline

1
A superconformal index primer
superconformal algebra · superconformal index · Römelsberger's prescription
2
Quiver gauge theories and brane tilings
quiver + superpotential · D3-branes on a toric CY\(_3\) · bipartite graphs on \(T^2\)
3
Seiberg duality
spider moves on the tiling · Spiridonov's / Rains's theorem
4
Quiver-invariant duality
phases with a common quiver · an R-charge involution of the index
5
Conclusion and outlook
constraining the functional form of the index

Chapter 1

A superconformal index primer

from the conformal algebra to elliptic gamma integrals

The conformal algebra

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 \(S^3\).

The superconformal algebra

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 \(\mathcal{Q}\).

Defining an index

Defining the superconformal index

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.

The Römelsberger prescription

Restrict the trace to the \(\mathcal{Q}\)-closed letters of one free multiplet, then plethystically exponentiate and project onto gauge invariants:

\[ i_\chi(p,q;R_\chi)=\frac{(pq)^{R_\chi/2}-(pq)^{1-R_\chi/2}}{(1-p)(1-q)}\,,\qquad i_V(p,q)=-\frac{p}{1-p}-\frac{q}{1-q}+\frac{2pq}{(1-p)(1-q)}\,, \] \[ \mathcal{I}=\int_G[dU]\ \mathrm{PE}\Big[i_V\,\chi_{\rm adj}(U)+\textstyle\sum_i i_\chi(p,q;R_i)\,\chi_{\mathcal{R}_i}(U,\vec v)\Big]\,,\qquad \Gamma(z;p,q)=\prod_{j,k\ge0}\frac{1-z^{-1}p^{j+1}q^{k+1}}{1-z\,p^{j}q^{k}}\,. \]


Chiral multiplet

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.

Vector multiplet

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 \((a;b)_\infty=\prod_{k\ge0}(1-ab^k)\).

Now let's apply this to familiar theories

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

\[ \begin{aligned} \mathcal{I}(p,q\,|\,r_{ij}) &= \prod_{k=1}^{G}\left(\frac{\kappa^{N-1}}{N!} \oint_{\mathbb{T}_{N-1}}\prod_{i=1}^{N-1}\frac{dz^{(k)}_i}{2\pi i z^{(k)}_i} \prod_{1\le l<m\le N}\frac{1}{\Gamma(z^{(k)}_l/z^{(k)}_m,z^{(k)}_m/z^{(k)}_l;p,q)}\right)\\ &\quad\times\prod_{X_{ij}}\prod_{l,m=1}^{N}\Gamma\big(t^{3r_{ij}}z^{(i)}_l/z^{(j)}_m;p,q\big) \end{aligned} \]

a quiver \(Q\) + a superpotential \(W\) R-charges \(r_{ij}\) the index

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

Quiver gauge theories and brane tilings

D3-branes probing a toric Calabi–Yau, drawn on a torus

Quiver gauge theory — reading the diagram

building up \(F_0=\mathbb{P}^1\!\times\!\mathbb{P}^1\), phase I

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: \(\;W_{F_0}=\epsilon^{ij}\epsilon^{pq}\,A_i B_p C_j D_q\).

Quiver gauge theory — superpotential and fixed point

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 \(\Delta=\tfrac32 R\).

Brane tilings



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 \(T^2\), \(\;F-E+V=0\).

quiver of \(F_0\)

Chapter 3

Seiberg duality

spider moves on the tiling, identities on the index

Seiberg duality and the spider move


\(SU(N_c)\) 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 \(N_f=2N_c\).

urban renewal on a square face

The model — \(H_{1,1,2,1}\)

brane tiling
phase 2a

\(H_{1,1,2,1}=H_{1,1,1,2}=\mathrm{PdP}_{5c}\)

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.

phase 2a Seiberg duality, node 9
toric diagram
two internal points

Seiberg duality on the quiver gauge theory

dualize a node with \(N_f=2N_c\)quadrilateral facespider move / urban renewaltoric duality
(toric) Seiberg duality graph — H1,1,2,1

\(\mathcal{M}_{\rm mes}\) is unchanged: one geometry, many toric phases, organized into a duality tree.

Seiberg duality on the superconformal index

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 \(n\),

\[ I_n\big(\left\{\tfrac{t^{3r_{na}}}{z^{(a)}}\right\}_{a\leftarrow n},\{t^{3r_{bn}}z^{(b)}\}_{b\rightarrow n}\big) =\oint\!\mu(z^{(n)})\prod_{l,m=1}^{N}\Big(\prod_{a\leftarrow n}\Gamma\big(t^{3r_{na}} z^{(n)}_l/z^{(a)}_m\big)\prod_{b\rightarrow n}\Gamma\big(t^{3r_{bn}}z^{(b)}_l/z^{(n)}_m\big)\Big)\,, \]

\[ I_n\big(\left\{\tfrac{t^{3r_{na}}}{z^{(a)}}\right\}_{a\leftarrow n},\{t^{3r_{bn}}z^{(b)}\}_{b\rightarrow n}\big) =\prod_{l,m=1}^{N}\prod_{\substack{a\leftarrow n\\ b\rightarrow n}}\Gamma\big(t^{3(r_{na}+r_{bn})}z^{(b)}_l/z^{(a)}_m\big)\ \times\ I_n\big(\left\{\tfrac{t^{3(U-r_{bn})}}{z^{(b)}}\right\}_{b\rightarrow n},\{t^{3(T-r_{na})}z^{(a)}\}_{a\leftarrow n}\big) \]

prefactor \(\Gamma(t^{3(r_{na}+r_{bn})}\,\cdot)\) = the mesons \(M_{ba}\) · swapped arguments = reversed arrows at \(n\)

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

Quiver-invariant duality

same quiver, different superpotential

Brane tilings with a common quiver

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.

fundamental domain of \(T^2\) the quiver, one node per face node 9 — the dualized face
\(H_{1,1,2,1}\) — phase 2a
Seiberg duality
\(H_{1,1,2,1}\) — phase 2b

The superconformal index identity

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.

Seiberg duality on node 9, step by step

node 9 and its arrows mesons from Rains's identity massive — integrated out R-charge changed

Conclusion and outlook

What we have

  • Toric phases of a brane tiling that share a common quiver but differ in \(W\) — five doublets and one triplet for \(H_{1,1,2,1}\).
  • Their superconformal indices coincide as elliptic hypergeometric integrals, giving an exact involution on the R-charges.
  • Unlike Rains's theorem, these identities are not local: they are tied to the global structure of the quiver.
  • A recipe for genereting infinitely many global constraints. Look at larger brane-tiling for further identities (eg. \(PdP_{6c}\), \(H^{1,3,1,2}\), \(H^{1,1,2,2}\), etc).

Where it points

  • A new way of constraining the functional form of the index: any candidate closed form, written as a combination of special functions, must reproduce these identities.
  • Compute the residue sum explicitly — following van Leuven–Mathieson–Roy and Pan–Peelaers — and extend the identities to that representation.
  • The triplet points to quiver-invariant dualities beyond the doublet pattern.

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.

Thank you

Questions are always welcome — b.suzzoni@benterre.com