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
Abstract
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
How to cite

Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete.

Open Access