Open Charm Spectroscopy and Mass Measurements in LHCb

TL;DR

This paper reports on the observation and characterization of various charm meson resonances, including the $D_1(2420)^0$ and $D^*_2(2460)$, using LHCb data, and provides precise measurements of $D$ meson mass differences.

Contribution

It presents new measurements of charm meson resonance properties and mass differences, and reports the observation of previously unmeasured structures in the 2500-2800 MeV region.

Findings

Observation of $D_1(2420)^0$ and $D^*_2(2460)$ resonances with properties and spin-parity assignments.

Detection of additional natural and unnatural parity resonances between 2500 and 2800 MeV.

Precise measurements of $D$ meson mass differences and the $D^{0}$ mass.

Abstract

A study of $D^+\pi^-$, $D^0 \pi^+$ and $D^{*+}\pi^-$ final states is performed using pp collision data, corresponding to an integrated luminosity of 1.0 $fb^{-1}$, collected at a centre-of-mass energy of 7 TeV with the LHCb detector. The $D_1(2420)^0$ resonance is observed in the $D^{*+}\pi^-$ final state and the $D^*_2(2460)$ resonance is observed in the $D^+\pi^-$, $D^0 \pi^+$ and $D^{*+}\pi^-$ final states. For both resonances, their properties and spin-parity assignments are obtained. In addition, two natural parity and two unnatural parity resonances are observed in the mass region between 2500 and 2800 MeV. Further structures in the region around 3000 MeV are observed in all the $D^{*+}\pi^-$, $D^+\pi^-$ and $D^0 \pi^+$ final states. Using three- and four-body decays of $D$ mesons produced in semileptonic $b$-hadron decays, precision measurements of $D$ meson mass differences are made together with a measurement of the $D^{0}$ mass.