Abstract
A search for the doubly charmed baryon {varXi}_{cc}^{+} is performed in the {varXi}_c^{+}{pi}^{-}{pi}^{+} invariant-mass spectrum, where the {varXi}_c^{+} baryon is reconstructed in the pK−π+ final state. The study uses proton-proton collision data collected with the LHCb detector at a centre- of-mass energy of 13 TeV, corresponding to a total integrated luminosity of 5.4 fb−1. No significant signal is observed in the invariant-mass range of 3.4–3.8 GeV/c2. Upper limits are set on the ratio of branching fractions multiplied by the production cross-section with respect to the {varXi}_{cc}^{++} → ( {varXi}_c^{+} → pK−π+)π+ decay for different {varXi}_{cc}^{+} mass and lifetime hypotheses in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 2.5 to 25 GeV/c. The results from this search are combined with a previously published search for the {varXi}_{cc}^{+} → {varLambda}_c^{+} K−π+ decay mode, yielding a maximum local significance of 4.0 standard deviations around the mass of 3620 MeV/c2, including systematic uncertainties. Taking into account the look-elsewhere effect in the 3.5–3.7 GeV/c2 mass window, the combined global significance is 2.9 standard deviations including systematic uncertainties.
Highlights
Consistent with a weak decay; and a precision mass measurement, 3621.55 ± 0.23 ± 0.30 MeV/c2 [16]
This paper presents a search for the doubly charmed baryon Ξc+c using the
This range covers both the Ξc+c mass measured by the SELEX experiment and the mass of the Ξc+c+ baryon measured by the LHCb experiment, and most theoretical predictions
Summary
The LHCb detector [60, 61] is a single-arm forward spectrometer covering the pseudorapidity range 2 < η < 5, designed for the study of particles containing b or c quarks. The tracking system provides a measurement of the momentum, p, of charged particles with a relative uncertainty that varies from 0.5% at low momentum to 1.0% at 200 GeV/c. The online event selection is performed by a trigger [67], which consists of a hardware stage, followed by a two-level software stage, which applies a full event reconstruction. The same alignment and calibration information is propagated to the offline reconstruction, ensuring consistent and high-quality particle identification (PID) information between the trigger and offline software. Decays of unstable particles are described by EvtGen [76], in which final-state radiation is generated using. The interaction of the generated particles with the detector, and its response, are implemented using the Geant toolkit [78, 79] as described in ref. The singly charmed Ξc+ decays are distributed according to a resonant model in which 55% of the Ξc+ decays proceed via the resonant decay pK∗(892)0 followed by the decay of the K∗(892)0 meson to K−π+ final state [81]
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