arXiv subjects

Pinak Banerjee

Publications and source records attributed to Pinak Banerjee.

7 recordsLinked to original sources

arXiv2026

Notes on (-2)-form symmetries

We study $(-2)$-form symmetries of a $d$-dimensional quantum field theory, via a $(-1)$-form symmetry of its $(d+1)$-dimensional Symmetry Topological Field Theory (SymTFT), realized by a non-genuine codimension-one defect in the SymTFT bulk attached to a spacetime-filling topological operator. Unlike a $(-1)$-form symmetry of a $d$-dimensional theory, which merely shifts a parameter of the absolute theory, a $(-2)$-form symmetry modifies the SymTFT action, and thereby relates theories whose ordinary global symmetries differ by anomaly data or by the associator data of a non-invertible symmetry. We illustrate the construction in two-dimensional toy models, three-dimensional ABJM-type theories, four-dimensional generalized Yang--Mills theory, and in a fusion-categorical example relating the non-invertible symmetries $\operatorname{Rep}(D_4)$ and $\operatorname{Rep}(Q_8)$. We then develop a club-sandwich realization, in which a quarter-gauging operation interfaces between IR phases of distinct RG flows of a common UV theory, and an alternative realization via nested discrete gauging. Finally, we present a holographic, top-down realization in which the type IIA Romans mass plays the role of a $(-2)$-form background for a three-dimensional Chern--Simons-matter theory, with shifts of the Romans mass realizing shifts of the boundary anomaly coefficients. We also discuss related constructions for coupled bulk--boundary systems.

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arXiv2026

Flux Quantization of Type IIA in Unstable K-Theory

The traditional conjecture that RR-flux is quantized in stable K-cohomology fails to account for the presence of NS-brane sources: These impose nonlinear relations -- reductions of the famous quadratic relation on M-brane flux -- that can only be captured by unstable nonabelian cohomology theories. Here we consider a deformation of unstable K-theory which properly quantizes the fluxes coupling to D0/D2/NS5-branes, find a twisted version that quantizes also the fluxes coupling to NS1/D4-branes, and show that this oxidizes to a proper electromagnetic quantization of M-brane fluxes.

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arXiv2026

Flux Quantization on M-Strings

The electric Gauss law in 11D SuGra is famously non-linear, whence its flux quantization must be in nonabelian cohomology. We have previously shown that the minimal admissible choice is 4-Cohomotopy, which in the presence of magnetized M5-probes takes its relative twistorial form. Here we discuss how this situation is further refined in the presence of M-string probes on the M5-worldvolume. Based on the superspace formulation of 11D SuGra, we find the nested Bianchi identities by iterating the superembedding construction for super p-branes. The resulting probe brane hierarchy (M1 on magnetized M5 in 11D bulk) turns out to admit flux quantization in a doubly-relative form of twisted Cohomotopy, classified by the factorization of the quaternionic Hopf fibration through the twistor fibration. The further equivariant refinement of this cohomology theory reduces on A-type singularities to a form of relative 2-Cohomotopy which geometrically engineers Chern-insulator phases on $\mathrm{M5}\cap \mathrm{A}_n$, with the M-string playing the role of gapped nodal lines.

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arXiv2026

M5 brane to D4 brane via cyclification of rational relative 3-cohomotopy

In this article, we start by re-deriving the equations of motion and Bianchi identities for the abelian D4 brane worldvolume. Noting that the 4-flux in M-Theory is rationally flux quantized in a non-abelian cohomology theory called 4-cohomotopy, and the three-flux on the M5 brane worldvolume in rational (twisted) 3-cohomotopy, we compute the minimal model for the cyclification of the quaternionic Hopf fibration which encodes the Bianchi identities for the fluxes on the D4 brane worldvolume after double dimensional reduction. The two pictures can be mapped to each other, and thus at the rational level, we conjecture a non-abelian relative cohomology theory for the D4 brane, fibered over the 10d Type IIA spacetime fluxes.

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arXiv2025

Gauge potentials on the M5 brane in twisted equivariant cohomotopy

In this article, we work out some variations on the discussion of the C-field flux densities in the Sati-Schreiber program. We start by explaining the need for global completion of the field content: the fluxes, the gauge potentials and the gauge transformations on the worldvolume of a single M5 brane in eleven-dimensional supergravity, and how this is encoded by the choice of flux quantization law. Assuming Hypothesis H that the 4-flux in M-Theory is flux quantized in a non-abelian cohomology theory called 4-cohomotopy, and the three-flux on the M5 brane worldvolume in (twisted) 3-cohomotopy, we generalize some previous calculations known in the literature to include twisting by background gravity and placing M5 branes on orbifolds. We show that the null concordances of cohomotopically charged fluxes give rise to the traditional gauge potentials and the null concordances of concordances give rise to the corresponding gauge transformations via surjections, in the cases of tangentially twisted cohomotopy, twistorial cohomotopy and equivariant twistorial cohomotopy. We construct the surjections explicitly for these cases and check the consistency relations with the corresponding Bianchi identities. Thus, we show how the traditional formulas for the local gauge potentials on M5 brane worldvolume on curved spacetimes and orbifolds are indeed reproduced by the homotopy theory and, as such, become amenable to global completion in cohomotopical charge quantization.

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arXiv2024

Inflationary non-Gaussianities in alpha vacua and consistency with conformal symmetries

We study the conformal invariance of inflationary non-Gaussianities associated with scalar fluctuations in a non-Bunch-Davies initial state, known as the $\alpha$-vacuum, in single-field slow-roll inflation. The $\alpha$-vacuum is a one-parameter family of states, including the Bunch-Davies one, that preserves the conformal symmetry of inflationary dynamics in a nearly de-Sitter space-time. Working within the leading slow-roll approximation, we compute the four-point scalar correlator (the trispectrum) in $\alpha$-vacuum using the in-in formalism. We check that the conformal Ward identities are met between the three and four-point scalar $\alpha$-vacua correlators. Surprisingly, this contrasts the previously reported negative result of the Ward identities being violated between the two and the three-point correlators. We have also extended the wave-functional method, previously used for correlators with Bunch-Davies initial condition, to compute the three and four-point scalar correlators in $\alpha$-vacua. The results obtained from the wave-function method match the corresponding in-in results, adding further justification to our check of Ward identities with $\alpha$-vacua correlators.

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arXiv2024

Worldvolume origin of Higher M Theories

Exceptional Periodicity (EP) has taught us that there are families of M Theory-like superalgebras in spacetime dimensions $11,19,27,\dots$ up to infinity. In this paper, we make the conjecture that M Theory at each level of EP can be realized as a brane worldvolume theory of an M Theory superalgebra at some higher level of EP.

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