The B_{c}^{+} meson is observed for the first time in heavy ion collisions. Data from the CMS detector are used to study the production of the B_{c}^{+} meson in lead-lead (Pb-Pb) and proton-proton (pp) collisions at a center-of-mass energy per nucleon pair of sqrt[s_{NN}]=5.02 TeV, via the B_{c}^{+}→(J/ψ→μ^{+}μ^{-})μ^{+}ν_{μ} decay. The B_{c}^{+} nuclear modification factor, derived from the Pb-Pb-to-pp ratio of production cross sections, is measured in two bins of the trimuon transverse momentum and of the Pb-Pb collision centrality. The B_{c}^{+} meson is shown to be less suppressed than quarkonia and most of the open heavy-flavor mesons, suggesting that effects of the hot and dense nuclear matter created in heavy ion collisions contribute to its production. This measurement sets forth a promising new probe of the interplay of suppression and enhancement mechanisms in the production of heavy-flavor mesons in the quark-gluon plasma.

Using a data sample of $$\sqrt{s}=13\,\text {TeV}$$ proton-proton collisions collected by the CMS experiment at the LHC in 2017 and 2018 with an integrated luminosity of $$103\text {~fb}^{-1}$$ , the $$\text {B}^{0}_{\mathrm{s}} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0}$$ and $$\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0} \uppi ^+\uppi ^-$$ decays are observed with significances exceeding 5 standard deviations. The resulting branching fraction ratios, measured for the first time, correspond to $${\mathcal {B}}(\text {B}^{0}_{\mathrm{s}} \rightarrow \uppsi (\text {2S})K_\mathrm{S}^{0})/{\mathcal {B}}(\text {B}^{0}\rightarrow \uppsi (\text {2S})K_\mathrm{S}^{0}) = (3.33 \pm 0.69 (\text {stat})\, \pm 0.11\,(\text {syst}) \pm 0.34\,(f_{\mathrm{s}}/f_{\mathrm{d}})) \times 10^{-2}$$ and $${\mathcal {B}}(\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0} \uppi ^{+} \uppi ^{-})/ {\mathcal {B}}(\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}^{0}_{\mathrm{S}}) = 0.480 \pm 0.013\,(\text {stat}) \pm 0.032\,(\text {syst})$$ , where the last uncertainty in the first ratio is related to the uncertainty in the ratio of production cross sections of $$\hbox {B}^{0}_{\mathrm{s}}$$ and $$\hbox {B}^{0}$$ mesons, $$f_{\mathrm{s}}/f_{\mathrm{d}}$$ .

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV.

The original article has been corrected.

A bstract A search is performed for rare and forbidden charm decays of the form $$ {D}_{(s)}^{+}\to {h}^{\pm }{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{\left(\prime \right)\mp } $$ D s + → h ± ℓ + ℓ ′ ∓ , where h ± is a pion or kaon and ℓ (′)± is an electron or muon. The measurements are performed using proton-proton collision data, corresponding to an integrated luminosity of 1 . 6 fb − 1 , collected by the LHCb experiment in 2016. No evidence is observed for the 25 decay modes that are investigated and 90 % confidence level limits on the branching fractions are set between 1 . 4 × 10 − 8 and 6 . 4 × 10 − 6 . In most cases, these results represent an improvement on existing limits by one to two orders of magnitude.

A search for the rare decay B-0 -> J/psi phi, is performed using pp collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb(-1). No significant signal of the decay is observed and an upper limit of 1.1 x 10(-7) at 90% confidence level is set on the branching fraction.

A search is presented for the lepton flavour violating decay B+ → K+μ−τ+ using a sample of proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, collected with the LHCb detector and corresponding to a total integrated luminosity of 9 fb−1. The τ leptons are selected inclusively, primarily via decays with a single charged particle. The four-momentum of the τ lepton is determined by using B+ mesons from $$ {B}_{s2}^{\ast 0}\to {B}^{+}{K}^{-} $$ decays. No significant excess is observed, and an upper limit is set on the branching fraction ℬ(B+ → K+μ−τ+) < 3.9 × 10−5 at 90 %  confidence level. The obtained limit is comparable to the world-best limit.

A search for $C\!P$ violation in the $\Lambda_b^0 \to p \pi^- \pi^+ \pi^-$ decay is performed using LHCb data corresponding to an integrated luminosity of 6.6$\,fb^{-1}$ collected in $pp$ collisions at centre-of-mass energies of 7, 8 and 13$\,Te\kern -0.1em V$. The analysis uses both triple product asymmetries and the unbinned energy test method. The highest significances of $C\!P$ asymmetry are 2.9 standard deviations from triple product asymmetries and 3.0 standard deviations for the energy test method. Once the global $p$-value is considered, all results are consistent with no $C\!P$ violation. Parity violation is observed at a significance of $5.5$ standard deviations for the triple product asymmetry method and $5.3$ standard deviations for the energy test method.

Abstract Using a data sample corresponding to an integrated luminosity of 2.0 $$\, \text {fb} ^{-1}$$ fb-1 , collected by the LHCb experiment, the production of the $${\eta _{c}} (1S)$$ ηc(1S) state in proton–proton collisions at a centre-of-mass energy of $$\sqrt{s} =13$$ s=13 $$\, \text {TeV}$$ TeV is studied in the rapidity range $$2.0< y < 4.5$$ 2.0

Using a data sample corresponding to an integrated luminosity of 2.0 $$\, \text {fb} ^{-1}$$, collected by the LHCb experiment, the production of the $${\eta _{c}} (1S)$$ state in proton–proton collisions at a centre-of-mass energy of $$\sqrt{s} =13$$ $$\, \text {TeV}$$ is studied in the rapidity range $$2.0< y < 4.5$$ and in the transverse momentum range $$6.5< p_{\mathrm {T}} < 14.0 \, \text {GeV} $$. The cross-section for prompt production of $${\eta _{c}} (1S)$$ mesons relative to that of the $${J /\psi }$$ meson is measured using the $$p $$ $$\overline{{p}}$$ decay mode and is found to be $${\sigma _{{\eta _{c}} (1S)}/\sigma _{{{J /\psi }}} = 1.69 \pm 0.15 \pm 0.10 \pm 0.18}$$. The quoted uncertainties are, in order, statistical, systematic and due to uncertainties on the branching fractions of the $${{J /\psi }} \!\rightarrow {p} {\overline{{p}}} $$ and $${\eta _{c}} \!\rightarrow {p} {\overline{{p}}} $$ decays. The prompt $${\eta _{c}} (1S)$$ production cross-section is determined to be $${\sigma _{{\eta _{c}} (1S)} = 1.26 \pm 0.11\pm 0.08\pm 0.14 \,\upmu \text {b}}$$, where the last uncertainty includes that on the $${J /\psi }$$ meson cross-section. The ratio of the branching fractions of $$b $$-hadron decays to the $${\eta _{c}} (1S)$$ and $${J /\psi }$$ states is measured to be $${{\mathcal {B}} _{{b} \!\rightarrow {\eta _{c}} X}/{\mathcal {B}} _{{b} \!\rightarrow {{J /\psi }} X} = 0.48 \pm 0.03 \pm 0.03 \pm 0.05}$$, where the last uncertainty is due to those on the branching fractions of the $${{J /\psi }} \!\rightarrow {p} {\overline{{p}}} $$ and $${\eta _{c}} \!\rightarrow {p} {\overline{{p}}} $$ decays. The difference between the $${J /\psi }$$ and $${\eta _{c}} (1S)$$ masses is also determined to be $$113.0 \pm 0.7 \pm 0.1 \, \text {MeV} $$, which is the most precise single measurement of this quantity to date.

Results are reported from an amplitude analysis of the $B^+\to D^+D^-K^+$ decay. The analysis is carried out using LHCb proton-proton collision data taken at $\sqrt{s}=7,8,$ and $13$ TeV, corresponding to a total integrated luminosity of 9 fb$^{-1}$. In order to obtain a good description of the data, it is found to be necessary to include new spin-0 and spin-1 resonances in the $D^-K^+$ channel with masses around 2.9 GeV$/c^2$, and a new spin-0 charmonium resonance in proximity to the spin-2 $\chi_{c2}(3930)$ state. The masses and widths of these resonances are determined, as are the relative contributions of all components in the amplitude model, which additionally include the vector charmonia $\psi(3770)$, $\psi(4040)$, $\psi(4160)$ and $\psi(4415)$ states and a nonresonant component.

In the Introduction section of the original article [1].

A measurement of four branching-fraction ratios for three-body decays of B mesons involving two open-charm hadrons in the final state is presented. Run 1 and Run 2 pp collision data are used, recorded by the LHCb experiment at centre-of-mass energies 7, 8, and 13 TeV and corresponding to an integrated luminosity of 9 fb−1. The measured branching-fraction ratios are $$ {\displaystyle \begin{array}{c}\frac{\mathcal{B}\left({B}^{+}\to {D}^{\ast +}{D}^{-}{K}^{+}\right)}{\mathcal{B}\left({B}^{+}\to {\overline{D}}^0{D}^0{K}^{+}\right)}=0.517\pm 0.015\pm 0.013\pm 0.011,\\ {}\frac{\mathcal{B}\left({B}^{+}\to {D}^{\ast -}{D}^{+}{K}^{+}\right)}{\mathcal{B}\left({B}^{+}\to {\overline{D}}^0{D}^0{K}^{+}\right)}=0.577\pm 0.016\pm 0.013\pm 0.013,\\ {}\begin{array}{c}\frac{\mathcal{B}\left({B}^0\to {D}^{\ast -}{D}^0{K}^{+}\right)}{\mathcal{B}\left({B}^0\to {D}^{-}{D}^0{K}^{+}\right)}=1.754\pm 0.028\pm 0.016\pm 0.035,\\ {}\frac{\mathcal{B}\left({B}^{+}\to {D}^{\ast +}{D}^{-}{K}^{+}\right)}{\mathcal{B}\left({B}^{+}\to {D}^{\ast -}{D}^{+}{K}^{+}\right)}=0.907\pm 0.033\pm 0.014,\end{array}\end{array}} $$ where the first of the uncertainties is statistical, the second systematic, and the third is due to the uncertainties on the D-meson branching fractions. These are the most accurate measurements of these ratios to date.

A four-body amplitude analysis of the B- -> D*(+)pi(-) pi(-) decay is performed, where fractions and relative phases of the various resonances contributing to the decay are measured. Several quasi-model-independent analyses are performed aimed at searching for the presence of new states and establishing the quantum numbers of previously observed charmed meson resonances. In particular the resonance parameters and quantum numbers are determined for the D-1 (2420), D-1 (2430), D-0 (2550), D-1* (2600), D-2 (2740) and D-3*(2750) states. The mixing between the D-1 (2420) and D-1 (2430) resonances is studied and the mixing parameters are measured. The dataset corresponds to an integrated luminosity of 4.7 fb(-1), collected in proton-proton collisions at center-of-mass energies of 7, 8 and 13 TeV with the LHCb detector.

This paper presents an analysis of the $$ {\Lambda}_b^0 $$→ J/ψΛ angular distribution and the transverse production polarisation of $$ {\Lambda}_b^0 $$ baryons in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The measurements are performed using data corresponding to an integrated luminosity of 4.9 fb−1, collected with the LHCb experiment. The polarisation is determined in a fiducial region of $$ {\Lambda}_b^0 $$ transverse momentum and pseudorapidity of 1 < pT< 20 GeV/c and 2 < η < 5, respectively. The data are consistent with $$ {\Lambda}_b^0 $$ baryons being produced unpolarised in this region. The parity-violating asymmetry parameter of the Λ → pπ− decay is also determined from the data and its value is found to be consistent with a recent measurement by the BES III collaboration.

This paper presents an analysis of the Λ^0_b→ J/ψΛ angular distribution and the transverse production polarisation of Λ^0_b baryons in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The measurements are performed using data corresponding to an integrated luminosity of 4.9 fb^-1, collected with the LHCb experiment. The polarisation is determined in a fiducial region of Λ^0_b transverse momentum and pseudorapidity of 1 < p_T < 20 GeV/c and 2 < η < 5, respectively. The data are consistent with Λ^0_b baryons being produced unpolarised in this region. The parity-violating asymmetry parameter of the Λ→ pπ^- decay is also determined from the data and its value is found to be consistent with a recent measurement by the BES III collaboration.

A bstract The decays B + → J / ψπ + π − K + are studied using a data set corresponding to an integrated luminosity of 9 fb − 1 collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate ψ 2 (3823), χ c1 (3872) and ψ(2S) states are reported. The values are $$ {\displaystyle \begin{array}{c}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\uppsi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi_2(3823)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\upchi}_{\mathrm{c}1}(3872){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\upchi_{\mathrm{c}1}(3872)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}=\left(3.56\pm 0.67\pm 0.11\right)\times {10}^{-2},\\ {}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\uppsi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi_2(3823)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to \uppsi \left(2\mathrm{S}\right){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi \left(2\mathrm{S}\right)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}=\left(1.31\pm 0.25\pm 0.04\right)\times {10}^{-3},\\ {}\frac{{\mathcal{B}}_{\mathrm{B}+\to {\upchi}_{\mathrm{c}1}(3872){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\upchi_{\mathrm{c}1}(3872)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to \uppsi \left(2\mathrm{S}\right){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi \left(2\mathrm{S}\right)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}=\left(3.69\pm 0.07\pm 0.06\right)\times {10}^{-2},\end{array}} $$ BB+→ψ23823K+×Bψ23823→J/ψπ+π−BB+→χc13872K+×Bχc13872→J/ψπ+π−=3.56±0.67±0.11×10−2,BB+→ψ23823K+×Bψ23823→J/ψπ+π−BB+→ψ2SK+×Bψ2S→J/ψπ+π−=1.31±0.25±0.04×10−3,BB+→χc13872K+×Bχc13872→J/ψπ+π−BB+→ψ2SK+×Bψ2S→J/ψπ+π−=3.69±0.07±0.06×10−2, where the first uncertainty is statistical and the second is systematic. The decay of B + → ψ 2 (3823)K + with ψ 2 (3823) → J / ψπ + π − is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the ψ 2 (3823), χ c1 (3872) and ψ(2S) states are measured to be $$ {\displaystyle \begin{array}{c}{m}_{\upchi_{\mathrm{c}1}(3872)}-{m}_{\uppsi_2(3823)}=47.50\pm 0.53\pm 0.13\;\mathrm{MeV}/{c}^2,\\ {}{m}_{\uppsi_2(3823)}-{m}_{\uppsi_2\left(2\mathrm{S}\right)}=137.98\pm 0.53\pm 0.14\;\mathrm{MeV}/{c}^2,\\ {}{m}_{\upchi_{\mathrm{c}1}(3872)}-{m}_{\uppsi_2\left(2\mathrm{S}\right)}=185.49\pm 0.06\pm 0.03\;\mathrm{MeV}/{c}^2,\end{array}} $$ mχc13872−mψ23823=47.50±0.53±0.13MeV/c2,mψ23823−mψ22S=137.98±0.53±0.14MeV/c2,mχc13872−mψ22S=185.49±0.06±0.03MeV/c2, resulting in the most precise determination of the χ c1 (3872) mass. The width of the ψ 2 (3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the χ c1 (3872) state is measured to be $$ {\Gamma}_{\upchi_{\mathrm{c}1}(3872)}^{\mathrm{BW}}={0.96}_{-0.18}^{+0.19}\pm 0.21\;\mathrm{MeV} $$ Γχc13872BW=0.96−0.18+0.19±0.21MeV which is inconsistent with zero by 5.5 standard deviations.