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Nature of χc1(3872) and Tcc+(3875)

Nora Brambilla1,2,3,*, Abhishek Mohapatra1,†, Tommaso Scirpa1,‡, and Antonio Vairo1,§

  • *Contact author: nora.brambilla@tum.de
  • †Contact author: abhishek.mohapatra@tum.de
  • ‡Contact author: tommaso.scirpa@tum.de
  • §Contact author: antonio.vairo@tum.de
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Phys. Rev. Lett. 135, 131902 – Published 23 September, 2025

DOI: https://doi.org/10.1103/pdy7-hvg7

Abstract

Two decades ago the χc1(3872) state was discovered in the hadron spectrum with two heavy quarks. The discovery fueled a surge in experimental research, uncovering dozens of so called XYZ exotics states lying outside the conventional quark model, as well as theoretical investigations into new forms of matter, such as quark-gluon hybrids, tetraquarks, and pentaquarks, with the potential of disclosing new information about the fundamental strong force. Among the XYZs, the χc1(3872) and Tcc+(3875) states stand out for their striking characteristics and unleashed many discussions about their nature. Here, we address this question using the Born-Oppenheimer effective field theory (BOEFT) and show how QCD settles the issue of their composition. Not only do we describe well the main features of the χc1(3872) and Tcc+(3875) states, but we also obtain predictions in the bottomonium sector. This opens the way to systematic applications of BOEFT to all XYZs.

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Phys. Rev. Lett. 135, 131902– Published 23 September, 2025
  • Received 26 November 2024
  • Revised 15 June 2025
  • Accepted 12 August 2025
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