Amplitude models are constructed to describe the resonance structure of
and
decays using
pp
collision data collected at centre-of-mass energies of 7 and 8 TeV with the LHCb experiment, corresponding to an integrated luminosity of 3.0
. The largest contributions to both decay amplitudes are found to come from axial resonances, with decay modes
and
being prominent in
and
, respectively. Precise measurements of the lineshape parameters and couplings of the
,
and
resonances are made, and a quasi model-independent study of the
resonance is performed. The coherence factor of the decays is calculated from the amplitude models to be
, which is consistent with direct measurements. These models will be useful in future measurements of the unitary-triangle angle
and studies of charm mixing and
violation.
The concept of isochronous mass spectrometry (IMS) applying two time-of-flight (TOF) detectors originated many years ago at GSI. However, the corresponding method for data analysis has never been discussed in detail. Recently, two TOF detectors have been installed at CSRe and the new working mode of the ring is under test. In this paper, a data analysis method for this mode is introduced and tested with a series of simulations. The results show that the new IMS method can significantly improve mass resolving power via the additional velocity information of stored ions. This improvement is especially important for nuclides with Lorentz factor γ-value far away from the transition point γt of the storage ring CSRe.
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