Observation of an exotic narrow doubly charmed tetraquark

TL;DR

This paper reports the discovery of a new narrow doubly charmed tetraquark state at the LHCb experiment, expanding the understanding of exotic hadronic matter beyond conventional baryons and mesons.

Contribution

First observation of a doubly charmed tetraquark with detailed mass and width measurements, demonstrating its resonance nature and exotic quark composition.

Findings

Mass of about 3875 MeV/c^2

Narrow width indicating a resonance

Observed as a peak below the D*+ D^0 threshold

Abstract

Conventional hadronic matter consists of baryons and mesons made of three quarks and quark-antiquark pairs, respectively. The observation of a new type of hadronic state, a doubly charmed tetraquark containing two charm quarks, an anti-$u$ and an anti-$d$ quark, is reported using data collected by the LHCb experiment at the Large Hadron Collider. This exotic state with a mass of about 3875 MeV$/c^2$ manifests itself as a narrow peak in the mass spectrum of $D^0D^0\pi^+$ mesons just below the $D^{*+}D^0$ mass threshold. The near threshold mass together with a strikingly narrow width reveals the resonance nature of the state.