[Paper Review] Fluxbranes, Generalized Symmetries, and Verlinde's Metastable Monopole

Mirjam Cvetič, Jonathan J. Heckman+2 more|arXiv (Cornell University)|May 16, 2023

Black Holes and Theoretical Physics4 citations

TL;DR

This paper proposes that fluxbranes—branes wrapped at infinity in string compactifications—realize continuous generalized global symmetries in 4D QFTs. It applies this framework to Verlinde’s metastable monopole, showing that gravity-induced decay triggers Hanany-Witten-like brane creation, leading to electric confinement via emergent topological sectors, with fluxbranes acting as symmetry operators that track the deconfinement-confinement transition.

ABSTRACT

The stringy realization of generalized symmetry operators involves wrapping "branes at infinity". We argue that in the case of continuous (as opposed to discrete) symmetries, the appropriate objects are fluxbranes. We use this perspective to revisit the phase structure of Verlinde's monopole, a proposed particle which is BPS when gravity is decoupled, but is non-BPS and metastable when gravity is switched on. Geometrically, this monopole is obtained from branes wrapped on locally stable but globally trivial cycles of a compactification geometry. The fluxbrane picture allows us to characterize electric (resp. magnetic) confinement (resp. screening) in the 4D theory as a result of monopole decay. In the presence of the fluxbrane, this decay also creates lower-dimensional fluxbranes, which in the field theory is interpreted as the creation of an additional topological field theory sector.

Motivation & Objective

• To understand the stringy realization of continuous generalized global symmetries in QFTs via branes at infinity.
• To analyze the phase structure of Verlinde’s metastable monopole in the presence of gravity using fluxbrane symmetry operators.
• To characterize the transition from deconfining to confining phases as a result of monopole decay and fluxbrane interactions.
• To identify how the creation of lower-dimensional fluxbranes via the Hanany-Witten effect corresponds to the emergence of a topological field theory sector in the effective 4D theory.

Proposed method

• The authors use branes wrapped on free relative cycles in compactification geometries to construct generalized symmetry operators, identifying fluxbranes as the correct objects for continuous symmetries.
• They analyze the monopole configuration as a D3-brane wrapping a non-compact 3-cycle in a Calabi-Yau threefold, with a flux tube from a D3-brane on a compact 2-cycle.
• The transition from BPS stability (gravity decoupled) to metastability (gravity included) is studied by embedding the system in a globally compact geometry where the 2-cycle becomes trivial.
• The Hanany-Witten effect is applied when the 5-brane bubble boundary collides with the fluxbrane, generating a fundamental flux 2-brane, which is shown to correspond to a topological field theory sector in the 4D effective theory.
• The Wess-Zumino actions for fluxbranes are derived from brane/anti-brane systems, with flux quantization enforced via Chern-Simons terms on higher-dimensional branes.
• The framework is extended to include higher-group symmetries and topological operators, with a focus on how gravity alters the fate of metastable monopoles.

Experimental results

Research questions

• RQ1 How do fluxbranes realize continuous generalized global symmetries in string-theoretic QFTs?
• RQ2 What is the role of fluxbranes in characterizing the deconfinement-confinement transition in Verlinde’s metastable monopole?
• RQ3 How does the Hanany-Witten effect manifest in the decay of the monopole, and what is its field-theoretic interpretation?
• RQ4 What is the topological field theory sector created by the decay-induced fluxbrane production?
• RQ5 How does the inclusion of gravity alter the stability and symmetry structure of the monopole configuration?

Key findings

• Fluxbranes are identified as the correct stringy realization of continuous generalized global symmetry operators, replacing standard branes at infinity.
• The metastable monopole in Verlinde’s construction decays when gravity is switched on, due to the global triviality of the supporting 2-cycle in a compact geometry.
• The decay process triggers the Hanany-Witten effect, producing a lower-dimensional flux 2-brane, which corresponds to the emergence of a topological field theory sector in the 4D effective theory.
• Electric confinement arises from the monopole decay, with the fluxbrane acting as a symmetry operator that tracks the transition from deconfined to confined phases.
• The fluxbrane worldvolume action is derived from brane/anti-brane systems with rational fluxes, using Chern-Simons terms on higher-dimensional branes to achieve correct quantization.
• The framework provides a top-down realization of generalized symmetries in compact backgrounds, with implications for black hole information and metastable symmetry breaking.