The EFT of Large Spin Mesons

TL;DR

This paper develops an effective field theory for large spin mesons modeled as rotating open strings in large N_c QCD, providing systematic spectrum predictions and exploring extensions to heavy quarks and lattice data comparisons.

Contribution

It formulates a consistent EFT for open spinning strings with light quarks, addressing endpoint singularities and deriving Regge trajectory spectra in a systematic expansion.

Findings

Derived spectrum for leading and daughter Regge trajectories.

Identified narrower applicability regime due to quark acceleration effects.

Compared predictions with 4d QCD meson spectroscopy data.

Abstract

We use effective string theory to study mesons with large spin $J$ in large $N_c$ QCD as rotating open strings. In the first part of this work, we formulate a consistent effective field theory (EFT) for open spinning strings with light quarks. Our EFT provides a consistent treatment of the endpoints' singularities that arise in the massless limit. We obtain results, in a systematic $1/J$ expansion, for the spectrum of the leading and daughter Regge trajectories. Interestingly, we find that the redshift factor associated with the quarks' acceleration implies that the applicability regime of the EFT is narrower compared to that of static flux tubes. In the second part of this work, we discuss several extensions of phenomenological interests, including mesons with heavy quarks, the quarks' spin and the daughter Regge trajectories associated with the worldsheet axion, a massive string mode identified in lattice simulations of $4d$ flux tubes. We compare our predictions with $4d$ QCD spectroscopy data, and suggest potential $stringy$ interpretations of the observed mesons. We finally comment on the relation between the EFT spectrum and the Axionic String Ansatz, a recently proposed characterization of the spectrum of Yang-Mills glueballs.