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The paper presents results of the search for new meson decays into charmonium and light hadrons in the final state. Relative branching fractions of the studied processes are measured. The contributions of intermediate resonant structures in light hadron systems are considered. Experimental data and theoretical predictions are compared for various mass combinations. The analysis is based on the data collected by the LHCb experiment in proton—proton collisions at the center-of-mass energies of 7, 8, and 13 TeV in the period from 2011 to 2018.

Let be an elementary Chevalley group of type , , , and  over a finite field of characteristic  or the integer residue ring modulo  . We show that a Sylow -subgroup  of  is regular if and only if the nilpotency length of  is less than  . We introduce and study some series of the combinatorial objects related to the root systems and structure constants of simple complex Lie algebras.

In the Standard Model of particle physics, the strength of the couplings of the b quark to the u and c quarks, | V ub | and | V cb |, are governed by the coupling of the quarks to the Higgs boson. Using data from the LHCb experiment at the Large Hadron Collider, the probability for the Λ b 0 baryon to decay into the p final state relative to the final state is measured. Combined with theoretical calculations of the strong interaction and a previously measured value of | V cb |, the first | V ub | measurement to use a baryonic decay is performed. This measurement is consistent with previous determinations of | V ub | using B meson decays to specific final states and confirms the existing incompatibility with those using an inclusive sample of final states. The accurate determination of quark mixing parameters is essential for the understanding of the Standard Model. The LHCb collaboration now reports the coupling strength of the b quark to the u quark through the measurement of a baryonic decay mode.

A bstract The production cross-section of J/ψ pairs is measured using a data sample of pp collisions collected by the LHCb experiment at a centre-of-mass energy of s = 13 TeV, corresponding to an integrated luminosity of 279 ±11 pb −1 . The measurement is performed for J/ψ mesons with a transverse momentum of less than 10 GeV/ c in the rapidity range 2 . 0 < y < 4 . 5. The production cross-section is measured to be 15 . 2 ± 1 . 0 ± 0 . 9 nb. The first uncertainty is statistical, and the second is systematic. The differential cross-sections as functions of several kinematic variables of the J/ψ pair are measured and compared to theoretical predictions.

A simple complex Lie algebra is characterized by a root system  and a Chevalley basis with the integer structure constants. The well-known arbitrariness of their choice for the niltriangular subalgebra  essentially affects the Lie-admissible algebra  (in the sense of Albert) over a field  such that  . We study the uniqueness of the (nonassociative) enveloping algebras  of classical types. The enumeration of ideals of the Lie algebras  and  for leads to the solution of some combinatorial problem listed in ACM SIGSAM Bulletin in 2001. The calculations of multiple combinatorial sums with -binomial coefficient use the integral representation method of combinatorial sums (the coefficient method).

The production of the η c ( 1 S ) state in proton-proton collisions is probed via its decay to the p p ¯ final state with the LHCb detector, in the rapidity range 2.0 < y < 4.5 and in the meson transverse-momentum range p T > 6.5 GeV / c . The cross-section for prompt production of η c ( 1 S ) mesons relative to the prompt J / ψ cross-section is measured, for the first time, to be σ η c ( 1 S ) / σ J / ψ = 1.74 ± 0.29 ± 0.28 ± 0 . 18 B at a centre-of-mass energy s = 7 TeV using data corresponding to an integrated luminosity of 0.7 fb - 1 , and σ η c ( 1 S ) / σ J / ψ = 1.60 ± 0.29 ± 0.25 ± 0 . 17 B at s = 8 TeV using 2.0 fb - 1 . The uncertainties quoted are, in order, statistical, systematic, and that on the ratio of branching fractions of the η c ( 1 S ) and J / ψ decays to the p p ¯ final state. In addition, the inclusive branching fraction of b -hadron decays into η c ( 1 S ) mesons is measured, for the first time, to be B ( b → η c X ) = ( 4.88 ± 0.64 ± 0.29 ± 0 . 67 B ) × 10 - 3 , where the third uncertainty includes also the uncertainty on the J / ψ inclusive branching fraction from b -hadron decays. The difference between the J / ψ and η c ( 1 S ) meson masses is determined to be 114.7 ± 1.5 ± 0.1 MeV / c 2 .

A bstract The differential branching fraction of the rare decay Λ b 0  →  Λμ + μ − is measured as a function of q 2 , the square of the dimuon invariant mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of 3 . 0 fb −1 , collected by the LHCb experiment. Evidence of signal is observed in the q 2 region below the square of the J/ψ mass. Integrating over 15 < q 2 < 20 GeV 2 /c 4 the differential branching fraction is measured as d ℬ Λ b 0 → Λ μ + μ − / d q 2 = 1.18 − 0.08 + 0.09 ± 0.03 ± 0.27 × 10 − 7 GeV 2 / c 4 − 1 , where the uncertainties are statistical, systematic and due to the normalisation mode, Λ b 0  →  J / ψΛ , respectively. In the q 2 intervals where the signal is observed, angular distributions are studied and the forward-backward asymmetries in the dimuon ( A FB ℓ ) and hadron ( A FB h ) systems are measured for the first time. In the range 15 < q 2 < 20 GeV 2 /c 4 they are found to be A F B ℓ = − 0.05 ± 0.09 stat ± 0.03 syst and A F B h = − 0.29 ± 0.07 stat ± 0.03 syst .