A recent report of events by the BESIII collaboration suggests the presence of a structure at 3900 MeV. We argue that this structure, called in the past, is not in fact due to a new resonance but rather naturally emerges due to a combination of interference between nearby resonances and the opening of the channel. We further find that the appearance of this structure does not require suppression because of a radial node in the wave function, although a node improves fit quality. The measured coupling of is found to be substantially smaller than previously estimated. In addition, we report new corrections to the measured cross section at energies near . Published by the American Physical Society2024
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Angular analysis of the e+e−→D(*)±D*∓ process near the open charm threshold using initial-state radiation
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Garisto, R (Ed.)The ratios of branching fractions R(D*)= B(B0 --> D*+tau- nu(bar))/ B(B0--> D*+mu- nu(bar)) and R(D)= B(B0 --> D0tau- nu(bar))/ B(B0 --> D0mu- nu(bar)) are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb−1 of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode τ− → μ−ντν¯μ. The measured values are R*D*)= 0.281+/- 0.018+/- 0.024 and R(D0)=0.441+/- 0.060+/- 0.066, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is ρ= −0.43. The results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the standard modelmore » « less