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Using e(+)e(-) collision datasets corresponding to a total integrated luminosity of 21.7 fb(-1) collected with the BESIII detector at the BEPCII collider at center-of-mass energies ranging from 4.009 GeV to 4.951 GeV, the energy-dependent cross sections of e(+)e-->-Lambda<overline>+. are measured for the first time. By fitting these energy-dependent cross sections, we search for the excited psi states psi(4160) and psi(4415), and the vector charmonium-like states psi(4230), psi(4360), and psi(4660). No evidence for these is observed and the upper limits on the branching fractions of these states decaying into -Lambda+.. are set at the 90% confidence level.

Abstract 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 ψ2(3823), χc1(3872) and ψ(2S) states are reported. The values are B B + → ψ 2 3823 K + × B ψ 2 3823 → J / ψπ + π − B B + → χ c 1 3872 K + × B χ c 1 3872 → J / ψπ + π − = 3.56 ± 0.67 ± 0.11 × 10 − 2 , B B + → ψ 2 3823 K + × B ψ 2 3823 → J / ψπ + π − B B + → ψ 2 S K + × B ψ 2 S → J / ψπ + π − = 1.31 ± 0.25 ± 0.04 × 10 − 3 , B B + → χ c 1 3872 K + × B χ c 1 3872 → J / ψπ + π − B B + → ψ 2 S K + × B ψ 2 S → J / ψπ + π − = 3.69 ± 0.07 ± 0.06 × 10 − 2 ,$$ {\\displaystyle \\begin{array}{c}\\frac{{\\mathcal{B}}_{{\\mathrm{B}}^{+}\\to {\\uppsi}_2(3823){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\uppsi_2(3823)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}{{\\mathcal{B}}_{{\\mathrm{B}}^{+}\\to {\\upchi}_{\\mathrm{c}1}(3872){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\upchi_{\\mathrm{c}1}(3872)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}=\\left(3.56\\pm 0.67\\pm 0.11\\right)\\times {10}^{-2},\\\ {}\\frac{{\\mathcal{B}}_{{\\mathrm{B}}^{+}\\to {\\uppsi}_2(3823){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\uppsi_2(3823)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}{{\\mathcal{B}}_{{\\mathrm{B}}^{+}\\to \\uppsi \\left(2\\mathrm{S}\\right){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\uppsi \\left(2\\mathrm{S}\\right)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}=\\left(1.31\\pm 0.25\\pm 0.04\\right)\\times {10}^{-3},\\\ {}\\frac{{\\mathcal{B}}_{\\mathrm{B}+\\to {\\upchi}_{\\mathrm{c}1}(3872){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\upchi_{\\mathrm{c}1}(3872)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}{{\\mathcal{B}}_{{\\mathrm{B}}^{+}\\to \\uppsi \\left(2\\mathrm{S}\\right){\\mathrm{K}}^{+}}\\times {\\mathcal{B}}_{\\uppsi \\left(2\\mathrm{S}\\right)\\to \\mathrm{J}/{\\uppsi \\uppi}^{+}{\\uppi}^{-}}}=\\left(3.69\\pm 0.07\\pm 0.06\\right)\\times {10}^{-2},\\end{array}} $$where the first uncertainty is statistical and the second is systematic. The decay of B+ → ψ2(3823)K+ with ψ2(3823) → J/ψπ+π − is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the ψ2(3823), χc1(3872) and ψ(2S) states are measured to be m χ c 1 3872 − m ψ 2 3823 = 47.50 ± 0.53 ± 0.13 MeV / c 2 , m ψ 2 3823 − m ψ 2 2 S = 137.98 ± 0.53 ± 0.14 MeV / c 2 , m χ c 1 3872 − m ψ 2 2 S = 185.49 ± 0.06 ± 0.03 MeV / c 2 ,$$ {\\displaystyle \\begin{array}{c}{m}_{\\upchi_{\\mathrm{c}1}(3872)}-{m}_{\\uppsi_2(3823)}=47.50\\pm 0.53\\pm 0.13\\;\\mathrm{MeV}/{c}^2,\\\ {}{m}_{\\uppsi_2(3823)}-{m}_{\\uppsi_2\\left(2\\mathrm{S}\\right)}=137.98\\pm 0.53\\pm 0.14\\;\\mathrm{MeV}/{c}^2,\\\ {}{m}_{\\upchi_{\\mathrm{c}1}(3872)}-{m}_{\\uppsi_2\\left(2\\mathrm{S}\\right)}=185.49\\pm 0.06\\pm 0.03\\;\\mathrm{MeV}/{c}^2,\\end{array}} $$resulting in the most precise determination of the χc1(3872) mass. The width of the ψ2(3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the χc1(3872) state is measured to be Γ χ c 1 3872 BW = 0.96 − 0.18 + 0.19 ± 0.21 MeV$$ {\\Gamma}_{\\upchi_{\\mathrm{c}1}(3872)}^{\\mathrm{BW}}={0.96}_{-0.18}^{+0.19}\\pm 0.21\\;\\mathrm{MeV} $$which is inconsistent with zero by 5.5 standard deviations.

Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb −1 , collected with the LHCb detector between 2011 and 2018, a new narrow charmonium state, the X(3842) resonance, is observed in the decay modes$$ \\mathrm{X}(3842)\\to {D}^0{\\overline{D}}^0 $$X 3842 → D 0 D ¯ 0 and X(3842) → D + D − . The mass and the natural width of this state are measured to be$$ \\begin{array}{l}{m}_{X(3842)}=3842.71\\pm 0.16\\pm 0.12\\ MeV/{c}^2,\\hfill \\\ {}{\\varGamma}_{X(3842)}=2.79\\pm 0.51\\pm 0.35\\ MeV,\\hfill \\end{array} $$m X 3842 = 3842.71 ± 0.16 ± 0.12 M e V / c 2 , Γ X 3842 = 2.79 ± 0.51 ± 0.35 M e V , where the first uncertainty is statistical and the second is systematic. The observed mass and narrow natural width suggest the interpretation of the new state as the unobserved (spin-3 ψ 3 1 3 D 3 ) charmonium state. In addition, prompt hadroproduction of the ψ (3770) and χ 2 (3930) states is observed for the first time, and the parameters of these states are measured to be$$ \\begin{array}{l}{m}_{\\psi (3770)}=3778.1\\pm 0.7\\pm 0.6\\ MeV/{c}^2,\\hfill \\\ {}{m}_{\\chi_2(3930)}=3921.9\\pm 0.6\\pm 0.2\\ MeV/{c}^2,\\hfill \\\ {}{\\varGamma}_{\\chi_2(3930)}=36.6 \\pm 1.9 \\pm 0.9\\ MeV,\\hfill \\end{array} $$m ψ 3770 = 3778.1 ± 0.7 ± 0.6 M e V / c 2 , m χ 2 3930 = 3921.9 ± 0.6 ± 0.2 M e V / c 2 , Γ χ 2 3930 = 36.6 ± 1.9 ± 0.9 M e V , where the first uncertainty is statistical and the second is systematic.

The production ratio of psi(2S) to J/psi charmonium states is presented as a function of multiplicity in proton-lead collisions at a centre-of-mass energy of root s(NN) = 8.16TeV, for both prompt and nonprompt sources. The total luminosity recorded by the LHCb experiment corresponds to 13.6 nb(-1) for pPb collisions and 20.8 nb(-1) for Pbp collisions, where the first particle corresponds to the particle traveling towards the detector. Measurements are performed in the dimuon final state at forward (backward) centre-of-mass rapidity, with respect to the proton direction, 1.5 < y* < 4.0 (-5.0 < y* < -2.5) for pPb (Pbp) collisions. A multiplicity dependence of the prompt production ratio is observed in pPb collisions, whereas no dependence is found in nonprompt production, nor in either prompt or nonprompt production in Pbp collisions. These results suggest that in the Pb-going direction additional suppression mechanisms beyond comover effects may be present, possibly related to the formation of quark-gluon plasma. This highlights a transition from small to large collision systems and provides important insight into the suppression of charmonia in proton-nucleus collisions.

Using a sample of (2.712 ± 0.014) x 10 9 ψ (3686) events collected with the BESIII detector at the electron positron collider BEPCII, the decay ψ (3686) → Ξ - K S 0 Ω + <over bar> + c.c. is observed for the first time, which has a significance of 5.9 standard deviations. The branching fraction of this decay is measured to be (2.91 ± 0.47 ± 0.33) x 10 -6 , where the first and second uncertainties are statistical and systematic, respectively. The ratio between B ψ (3686)→Ξ - KS 0 Ω + <over bar>+c.c and B ψ(3686) → Ω - K + Ξ 0 <over bar>+c.c. is determined to be 1.05 ± 0.23 ± 0.14, which deviates from the isospin symmetry conservation predicted value of 0.5 by 2.1σ.

Based on (2712 . 4 ± 14 . 3) × 10 6 ψ (3686) events collected at the BESIII detector operating at the BEPCII collider, we present the first observation of the decay ψ(3686)→K−Λ(1520)¯Ξ+ + c.c.. The product branching fraction B[ψ(3686)→K−Λ(1520)¯Ξ++c.c.]×B[Λ(1520)→pK−] is measured to be (9 . 47 ± 0 . 75 ± 0 . 97) × 10 − 7 , where the first uncertainty is statistical and the second systematic.

Abstract We propose the Regge trajectory relations for the fully heavy pentaquarkP_(ccc̅bb)utilizing both diquark and triquark Regge trajectory relations. Using these new relations, we discuss four series of Regge trajectories: the ρ 1-, ρ 2-, λ 1-, and λ 2-trajectories. We provide rough estimates for the masses of the ρ 1-, ρ 2-, λ 1-, and λ 2-excited states. Except for the λ 1-trajectories, the complete forms of the other three series of Regge trajectories for the pentaquarkP_(ccc̅bb)are lengthy and cumbersome. We show that the ρ 1-, ρ 2-, and λ 2-trajectories can not be obtained by simply imitating the meson Regge trajectories because mesons have no substructures. To derive these trajectories, pentaquark’s structure and substructure should be taken into consideration. Otherwise, the ρ 1-, ρ 2-, and λ 2-trajectories must rely solely on fitting existing theoretical or future experimental data. Consequently, the fundamental relationship between the slopes of the obtained trajectories and constituents’ masses and string tension will become unobvious, and the predictive power of the Regge trajectories would be compromised. Moreover, we show that the lengthy complete forms of the ρ 1-, ρ 2-, and λ 2-trajectories can be well approximated by the simple fitted formulas. Four series of Regge trajectories for the pentaquarkP_(ccc̅bb)all exhibit a behavior of M x 2/3, where x = n r1, n r2, l 1, l 2, N r1, N r2, L 1, L 2. All four series of trajectories exhibit concave downward behavior in the (M 2, x) plane.

Using (27.12 ± 0.14) x 10 8 ψ(3686) events collected with the BESIII detector at BEPCII, the decay of ψ(3686) → Ω - K + Ξ 0 <over bar> + c.c. is observed for the first time. The branching fraction of this decay is measured to be B ψ(3686) → Ω - K + Ξ 0 <over bar> + c.c. = (2.78 ± 0.40 ± 0.18) x 10 -6 , where the first uncertainty is statistical and the second is systematic. Possible baryon excited states are searched for in this decay, but no evident intermediate state is observed with the current sample size.

The radiative decays χ c1 (3872) → ψ(2S) γ and χ c1 (3872) → J/ψγ are used to probe the nature of the χ c1 (3872) state using proton-proton collision data collected with the LHCb detector, corresponding to an integrated luminosity of 9 fb − 1 . Using the B + → χ c1 (3872)K + decay, the χ c1 (3872) → ψ(2S) γ process is observed for the first time and the ratio of its partial width to that of the χ c1 (3872) → J/ψγ decay is measured to be Γχc1(3872)→ψ(2S)γ/Γχc1(3872)→J/ψγ= 1.67 ± 0.21 ± 0.12 ± 0.04, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainties on the branching fractions of the ψ(2S) and J/ψ mesons. The measured ratio makes the interpretation of the χ c1 (3872) state as a pure D 0 D‾ *0 + D‾ 0 D *0 molecule questionable and strongly indicates a sizeable compact charmonium or tetraquark component within the χ c1 (3872) state.

We report the first measurement of the inclusive e + e − →$$ b\\overline{b} $$b b ¯ →$$ {D}_s^{\\pm } $$D s ± X and e + e − →$$ b\\overline{b} $$b b ¯ → D 0 /$$ {\\overline{D}}^0 $$D ¯ 0 X cross sections in the energy range from 10 . 63 to 11 . 02 GeV. Based on these results, we determine σ ( e + e − →$$ {B}_s^0{\\overline{B}}_s^0 $$B s 0 B ¯ s 0 X ) and σ ( e + e − →$$ B\\overline{B} $$B B ¯ X ) in the same energy range. We measure the fraction of$$ {B}_s^0 $$B s 0 events at Υ(10860) to be f s = ($$ {22.0}_{-2.1}^{+2.0} $$22.0 − 2.1 + 2.0 )%. We determine also the ratio of the$$ {B}_s^0 $$B s 0 inclusive branching fractions$$ \\mathcal{B} $$B ($$ {B}_s^0 $$B s 0 → D 0 /$$ {\\overline{D}}^0 $$D ¯ 0 X ) /$$ \\mathcal{B} $$B ($$ {B}_s^0 $$B s 0 →$$ {D}_s^{\\pm } $$D s ± X ) = 0 . 416 ± 0 . 018 ± 0 . 092. The results are obtained using the data collected with the Belle detector at the KEKB asymmetric-energy e + e − collider.