PoS - Proceedings of Science
Volume 391 - 19th International Conference on B-Physics at Frontier Machines (BEAUTY2020) - Main session
CMS: New Results in Conventional and Exotic Spectroscopy
A. Di Florio
Full text: pdf
Published on: October 07, 2021
The present report summarises three recent CMS results in conventional and exotic spectroscopy.

Firstly the search for a narrow resonance decaying to $\Upsilon(1S) \mu^+ \mu^-$ performed with $pp$ collision data collected in 2016 with the CMS detector at the LHC in proton-proton collisions at $\sqrt{s}=13$ TeV, corresponding to an integrated luminosity of $35.9 \rm{fb}^{-1}$. A tetraquark ($bb\bar{b}\bar{b}$) search is performed for masses in the vicinity of four times the bottom quark mass, between $17.5$ and $19.5$ GeV, while a generic search for other resonances is performed for masses between $16.5$ and $27$ GeV. No significant excess of events compatible with a narrow resonance is observed in the data. Limits on the production cross section times branching fraction of its decay to four muons via an intermediate $\Upsilon(1S)$ resonance are set as a function of the resonance mass.

\hspace{0.5 cm} In the second part, the study of $B^+ \to J/\psi \bar{\Lambda }p$, performed using $pp$ collision data collected in 2012 at $\sqrt{s} = 8$ TeV, corresponding to an integrated luminosity of $19.6 \rm{fb}^{-1}$, is presented. The ratio of branching fractions $\mathcal{B}(B^+ \to J/\psi\Lambda p)/\mathcal{B}(B^+ \to J/\psi K^{∗}(892)^{+})$ is measured to be ($1.054 \pm 0.057\rm(stat) \pm 0.035\rm(syst) \pm 0.011$($\mathcal{B}$))\%. In addition the invariant mass distributions of the $J/\psi \Lambda$, $J/\psi p$, and $\Lambda p$ systems produced in the $B^+ \to J/\psi\bar{\Lambda} p$ decay are investigated. Using a model-independent angular amplitude analysis approach, it is shown that the observed invariant masses distributions are consistent with the contributions from excited kaons decaying to the $\Lambda p$ system.

\hspace{0.5 cm} Finally the study of excited $\Lambda^0_b$ baryons is reported, based on a data sample collected in 2016–2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of up to $140\;\rm{fb}^{-1}$. The existence of four excited $\Lambda^0_b$ states: $\Lambda_b(5912)^0$, $\Lambda_b(5920)^0$, $\Lambda_b(6146)^0$ and $\Lambda_b(6152)^0$ decaying to $\Lambda^0_b \pi^{+} \pi^{-}$ is confirmed. Also a broad excess of events in the $\Lambda^0_b \pi^{+} \pi^{-}$ mass distribution in the region of $6040\div6100$ MeV is observed.
DOI: https://doi.org/10.22323/1.391.0045
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