Modular symmetry of massive free fermions

Fuente: arXiv
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Main Authors: Downing, Max, Murthy, Sameer, Watts, Gerard M. T.
Format: Preprint
Published: 2023
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author Downing, Max
Murthy, Sameer
Watts, Gerard M. T.
author_facet Downing, Max
Murthy, Sameer
Watts, Gerard M. T.
contents We construct an infinite set of conserved tensor currents of rank $2n$, $n=1,2,\dots$, in the two-dimensional theory of free massive fermions, which are bilinear in the fermionic fields. The one-point functions of these currents on the torus depend on the modular parameter $τ$ and spin structure $(α,β)$. We show that, upon scaling the mass $m$ so as to keep the combination $m^2$Im($τ$) invariant, the one-point functions are non-holomorphic Jacobi forms of weights $(2n,0)$ or $(0,2n)$ and index 0, with respect to the modular parameter $τ$ and elliptic parameter $z=ατ+β$. In particular, we express the one-point functions as Kronecker-Eisenstein-type sums over the lattice $\mathbb{Z}τ+\mathbb{Z}$, which makes the modular symmetry manifest. We show that there is an action of three differential operators on these Jacobi forms which form an $\mathfrak{sl}_2(\mathbb{R})$ Lie algebra. Further we show that these Jacobi forms obey three differential equations arising from the representation theory of the Jacobi group.
format Preprint
id arxiv_https___arxiv_org_abs_2302_01251
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Modular symmetry of massive free fermions
Downing, Max
Murthy, Sameer
Watts, Gerard M. T.
High Energy Physics - Theory
We construct an infinite set of conserved tensor currents of rank $2n$, $n=1,2,\dots$, in the two-dimensional theory of free massive fermions, which are bilinear in the fermionic fields. The one-point functions of these currents on the torus depend on the modular parameter $τ$ and spin structure $(α,β)$. We show that, upon scaling the mass $m$ so as to keep the combination $m^2$Im($τ$) invariant, the one-point functions are non-holomorphic Jacobi forms of weights $(2n,0)$ or $(0,2n)$ and index 0, with respect to the modular parameter $τ$ and elliptic parameter $z=ατ+β$. In particular, we express the one-point functions as Kronecker-Eisenstein-type sums over the lattice $\mathbb{Z}τ+\mathbb{Z}$, which makes the modular symmetry manifest. We show that there is an action of three differential operators on these Jacobi forms which form an $\mathfrak{sl}_2(\mathbb{R})$ Lie algebra. Further we show that these Jacobi forms obey three differential equations arising from the representation theory of the Jacobi group.
title Modular symmetry of massive free fermions
topic High Energy Physics - Theory
url https://arxiv.org/abs/2302.01251