Observation of a new baryon state in the ${\Lambda }_b^0{\pi }^{+}{\pi }^{-}$ mass spectrum

Abstract

A new baryon state is observed in the ${\Lambda }_b^0{\pi }^{+}{\pi }^{-}$ mass spectrum with high significance using a data sample of $pp$ collisions, collected with the LHCb detector at centre-of-mass energies $\sqrt{s}=7,8$ and 13TeV, corresponding to an integrated luminosity of 9fb${}^{-1}$. The mass and natural width of the new state are measured to be \begin{eqnarray*} m & = & 6072.3 \pm 2.9 \pm 0.6 \pm 0.2 MeV\,, Γ& = & 72 \pm 11 \pm 2 MeV\,, \end{eqnarray*} where the first uncertainty is statistical and the second systematic. The third uncertainty for the mass is due to imprecise knowledge of the ${\Lambda }_b^0$ baryon mass. The new state is consistent with the first radial excitation of the ${\Lambda }_b^0$ baryon, the ${\Lambda }_b(2S{)}^0$ resonance. Updated measurements of the masses and the upper limits on the natural widths of the previously observed ${\Lambda }_b(5912{)}^0$ and ${\Lambda }_b(5920{)}^0$ states are also reported.

arXiv comment24 pages, 6 figures, All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2019-045.html

References in corpus (39)

• PYTHIA 6.4 Physics and Manual
• PYTHIA 6.2 Physics and Manual
• LHCb Detector Performance
• PHOTOS Monte Carlo: a precision tool for QED corrections in Z and W decays
• sPlot: a statistical tool to unfold data distributions
• The LHCb Trigger and its Performance in 2011
• Performance of the LHCb RICH detector at the LHC
• Heavy Baryons in a Quark Model
• Decay Chain Fitting with a Kalman Filter
• Spectroscopy and Regge trajectories of heavy baryons in the relativistic quark-diquark picture
• Performance of the LHCb Vertex Locator
• Efficient, reliable and fast high-level triggering using a bonsai boosted decision tree
• Performance of the LHCb Outer Tracker
• Performance of the LHCb muon system
• Mass distributions marginalized over per-event errors
• Improved performance of the LHCb Outer Tracker in LHC Run 2
• Assignments of ${\Lambda }_Q$ and ${\Xi }_Q$ baryons in the heavy quark-light diquark picture
• First Observation of Heavy Baryons Σ_b and Σ_b^*
• Observation of excited Lambda_b0 baryons
• LHCb Topological Trigger Reoptimization
• Measurement of the Λ_b^0, Ξ_b^- and Ω_b^- baryon masses
• Observation of two resonances in the ${\Lambda }_b^0{\pi }^{\pm }$ systems and precise measurement of ${\Sigma }_b^{\pm }$ and ${\Sigma }_b^{\ast \pm }$ properties
• Measurement of b-hadron masses
• Heavy quark symmetry in multi-hadron systems
• Observation of new resonances in the ${\Lambda }_b^0{\pi }^{+}{\pi }^{-}$ system
• Near-threshold $D\bar{D}$ spectroscopy and observation of a new charmonium state
• Assigning the newly reported ${\Sigma }_b(6097)$ as a $P$-wave excited state and predicting its partners
• Evidence for a bottom baryon resonance Lambda_b* in CDF data
• Observation of the decays ${\Lambda }_b^0\to {\chi }_{c1}p{K}^{-}$ and ${\Lambda }_b^0\to {\chi }_{c2}p{K}^{-}$
• Interpretation of the observed ${\Lambda }_b(6146{)}^0$ and ${\Lambda }_b(6152{)}^0$ states as 1$D$ bottom baryons
• Interpretation of the newly observed ${\Lambda }_b(6146{)}^0$ and ${\Lambda }_b(6152{)}^0$ states in a chiral quark model
• Measurement of the masses and widths of the bottom baryons Sigma_b+- and Sigma_b*+-
• Three-body scattering: Ladders and Resonances
• Decay properties of $P$-wave heavy baryons accompanied by vector mesons within light-cone sum rules
• Observation of ${\Lambda }_b^0\to \psi (2S)p{K}^{-}$ and ${\Lambda }_b^0\to J/\psi {\pi }^{+}{\pi }^{-}p{K}^{-}$ decays and a measurement of the ${\Lambda }_b^0$ baryon mass
• Canonical interpretation of the newly observed ${\Lambda }_b(6146{)}^0$ and ${\Lambda }_b(6152{)}^0$ via strong decay behaviors
• Fitting function for asymmetric peaks
• ${\chi }_{c1}$ and ${\chi }_{c2}$ resonance parameters with the decays ${\chi }_{c1,c2}\to J/\psi {\mu }^{+}{\mu }^{-}$
• Dipion decays of heavy baryons

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• 70 Years of Hyperon Spectroscopy: A review of strange $\Xi$, $\Omega$ baryons, and the spectrum of charmed and bottom baryons
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