Abstract A test of lepton universality, performed by measuring the ratio of the branching fractions of the B 0 → K *0 μ + μ − and B 0 → K *0 e + e − decays, R K * 0 $$ {R}_{K^{*0}} $$ , is presented. ...The K *0 meson is reconstructed in the final state K + π −, which is required to have an invariant mass within 100 MeV/c 2 of the known K *(892)0 mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of about 3 fb−1, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The ratio is measured in two regions of the dilepton invariant mass squared, q 2, to be R K * 0 = 0.66 − + 0.07 0.11 stat ± 0.03 syst f o r 0.045 < q 2 < 1.1 GeV 2 / c 4 , 0.69 − + 0.07 0.11 stat ± 0.05 syst f o r 1.1 < q 2 < 6.0 GeV 2 / c 4 . $$ {R}_{K^{*0}}=\left\{\begin{array}{l}{0.66_{-}^{+}}_{0.07}^{0.11}\left(\mathrm{stat}\right)\pm 0.03\left(\mathrm{syst}\right)\kern1em \mathrm{f}\mathrm{o}\mathrm{r}\kern1em 0.045<{q}^2<1.1\kern0.5em {\mathrm{GeV}}^2/{c}^4,\hfill \\ {}{0.69_{-}^{+}}_{0.07}^{0.11}\left(\mathrm{stat}\right)\pm 0.05\left(\mathrm{syst}\right)\kern1em \mathrm{f}\mathrm{o}\mathrm{r}\kern1em 1.1<{q}^2<6.0\kern0.5em {\mathrm{GeV}}^2/{c}^4.\hfill \end{array}\right. $$ The corresponding 95.4% confidence level intervals are 0.52, 0.89 and 0.53, 0.94. The results, which represent the most precise measurements of R K * 0 $$ {R}_{K^{*0}} $$ to date, are compatible with the Standard Model expectations at the level of 2.1–2.3 and 2.4–2.5 standard deviations in the two q 2 regions, respectively.
Abstract The decays of B s 0 and B ¯ s 0 $$ {\overline{B}}_s^0 $$ mesons into the J/ψK + K − final state are studied in the K + K − mass region above the ϕ(1020) meson in order to determine the ...resonant substructure and measure the CP-violating phase, ϕ s , the decay width, Γ s , and the width difference between light and heavy mass eigenstates, ΔΓ s . A decay-time dependent amplitude analysis is employed. The data sample corresponds to an integrated luminosity of 3 fb−1 produced in 7 and 8 TeV pp collisions at the LHC, collected by the LHCb experiment. The measurement determines ϕ s = 119 ± 107 ± 34 mrad. A combination with previous LHCb measurements using similar decays into the J/ψπ + π − and J/ψϕ(1020) final states gives ϕ s = 1 ± 37 mrad, consistent with the Standard Model prediction.
Abstract Production cross-sections of prompt charm mesons are measured using data from pp collisions at the LHC at a centre-of-mass energy of 5 TeV. The data sample corresponds to an integrated ...luminosity of 8.60 ± 0.33 pb−1 collected by the LHCb experiment. The production cross-sections of D 0, D +, D s + , and D ∗+ mesons are measured in bins of charm meson transverse momentum, p T, and rapidity, y. They cover the rapidity range 2.0 < y < 4.5 and transverse momentum ranges 0 < p T < 10 GeV/c for D 0 and D + and 1 < p T < 10 GeV/c for D s + and D ∗+ mesons. The inclusive cross-sections for the four mesons, including charge-conjugate states, within the range of 1 < p T < 8 GeV/c are determined to be σ pp → D 0 X = 1004 ± 3 ± 54 μ b , σ pp → D + X = 402 ± 2 ± 30 μ b , σ pp → D s + X = 170 ± 4 ± 16 μ b , σ pp → D ∗ + X = 421 ± 5 ± 36 μ b , $$ \begin{array}{l}\sigma \left( pp\to {D}^0X\right)=1004\pm 3\pm 54\mu \mathrm{b},\\ {}\sigma \left( pp\to {D}^{+}X\right)=402\pm 2\pm 30\mu \mathrm{b},\\ {}\sigma \left( pp\to {D}_s^{+}X\right)=170\pm 4\pm 16\mu \mathrm{b},\\ {}\sigma \left( pp\to {D}^{\ast +}X\right)=421\pm 5\pm 36\mu \mathrm{b},\end{array} $$ where the uncertainties are statistical and systematic, respectively.
Abstract A search for the decay $${{K} ^0_{\mathrm { \scriptscriptstyle S}}} \rightarrow \mu ^+\mu ^-$$ KS0→μ+μ- is performed, based on a data sample of proton-proton collisions corresponding to an ...integrated luminosity of $$3\,\text{ fb }^{-1} $$ 3fb-1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8$$\mathrm {\,TeV}$$ TeV . The observed yield is consistent with the background-only hypothesis, yielding a limit on the branching fraction of $$\mathcal{B}({{K} ^0_{\mathrm { \scriptscriptstyle S}}} \rightarrow \mu ^+\mu ^-) < 0.8~(1.0) \times 10^{-9}$$ B(KS0→μ+μ-)<0.8(1.0)×10-9 at $$90\%~(95\%)$$ 90%(95%) confidence level. This result improves the previous upper limit on the branching fraction by an order of magnitude.
Abstract Using decays to $$\phi $$ ϕ -meson pairs, the inclusive production of charmonium states in $${b} $$ b -hadron decays is studied with pp collision data corresponding to an integrated ...luminosity of $$3.0 {\,\mathrm{fb}}^{-1} $$ 3.0 fb - 1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. Denoting by $${\mathcal {B}} _C \equiv {\mathcal {B}} ( {{b}} \!\rightarrow C X ) \times {\mathcal {B}} ( C\!\rightarrow \phi \phi )$$ B C ≡ B ( b → C X ) × B ( C → ϕ ϕ ) the inclusive branching fraction of a $${{b}} $$ b hadron to a charmonium state C that decays into a pair of $$\phi $$ ϕ mesons, ratios $$R^{C_1}_{C_2}\equiv {\mathcal {B}} _{C_1} / {\mathcal {B}} _{C_2}$$ R C 2 C 1 ≡ B C 1 / B C 2 are determined as $$R^{{\upchi _{{{c}} 0}}}_{{\eta _{{c}}} (1S)} = 0.147 \pm 0.023 \pm 0.011$$ R η c ( 1 S ) χ c 0 = 0.147 ± 0.023 ± 0.011 , $$R^{{\upchi _{{{c}} 1}}}_{{\eta _{{c}}} (1S)} = 0.073 \pm 0.016 \pm 0.006$$ R η c ( 1 S ) χ c 1 = 0.073 ± 0.016 ± 0.006 , $$R^{{\upchi _{{{c}} 2}}}_{{\eta _{{c}}} (1S)} = 0.081 \pm 0.013 \pm 0.005$$ R η c ( 1 S ) χ c 2 = 0.081 ± 0.013 ± 0.005 , $$R^{{\upchi _{{{c}} 1}}}_{{\upchi _{{{c}} 0}}} = 0.50 \pm 0.11 \pm 0.01$$ R χ c 0 χ c 1 = 0.50 ± 0.11 ± 0.01 , $$R^{{\upchi _{{{c}} 2}}}_{{\upchi _{{{c}} 0}}} = 0.56 \pm 0.10 \pm 0.01$$ R χ c 0 χ c 2 = 0.56 ± 0.10 ± 0.01 and $$R^{{\eta _{{c}}} (2S)}_{{\eta _{{c}}} (1S)} = 0.040 \pm 0.011 \pm 0.004$$ R η c ( 1 S ) η c ( 2 S ) = 0.040 ± 0.011 ± 0.004 . Here and below the first uncertainties are statistical and the second systematic. Upper limits at 90% confidence level for the inclusive production of X(3872), X(3915) and $${\upchi _{{{c}} 2}} (2P)$$ χ c 2 ( 2 P ) states are obtained as $$R^{X(3872)}_{{\upchi _{{{c}} 1}}} < 0.34$$ R χ c 1 X ( 3872 ) < 0.34 , $$R^{X(3915)}_{{\upchi _{{{c}} 0}}} < 0.12$$ R χ c 0 X ( 3915 ) < 0.12 and $$R^{{\upchi _{{{c}} 2}} (2P)}_{{\upchi _{{{c}} 2}}} < 0.16$$ R χ c 2 χ c 2 ( 2 P ) < 0.16 . Differential cross-sections as a function of transverse momentum are measured for the $${\eta _{{c}}} (1S)$$ η c ( 1 S ) and $$\chi _c$$ χ c states. The branching fraction of the decay $${{{B}} ^0_{{s}}} \!\rightarrow \phi \phi \phi $$ B s 0 → ϕ ϕ ϕ is measured for the first time, $${\mathcal {B}} ( {{{B}} ^0_{{s}}} \!\rightarrow \phi \phi \phi ) = (2.15 \pm 0.54 \pm 0.28 \pm 0.21_{{\mathcal {B}}}) \times 10^{-6}$$ B ( B s 0 → ϕ ϕ ϕ ) = ( 2.15 ± 0.54 ± 0.28 ± 0 . 21 B ) × 10 - 6 . Here the third uncertainty is due to the branching fraction of the decay $${{{B}} ^0_{{s}}} \!\rightarrow \phi \phi $$ B s 0 → ϕ ϕ , which is used for normalization. No evidence for intermediate resonances is seen. A preferentially transverse $$\phi $$ ϕ polarization is observed. The measurements allow the determination of the ratio of the branching fractions for the $${\eta _{{c}}} (1S)$$ η c ( 1 S ) decays to $$\phi \phi $$ ϕ ϕ and $${{p}} {\overline{{{p}}} $$ p p ¯ as $${\mathcal {B}} ( {\eta _{{c}}} (1S)\!\rightarrow \phi \phi )/{\mathcal {B}} ( {\eta _{{c}}} (1S)\!\rightarrow {{p}} {\overline{{{p}}} ) = 1.79 \pm 0.14\pm 0.32$$ B ( η c ( 1 S ) → ϕ ϕ ) / B ( η c ( 1 S ) → p p ¯ ) = 1.79 ± 0.14 ± 0.32 .
Abstract A search for the rare two-body charmless baryonic decay B + → p Λ ¯ $$ {B}^{+}\to p\overline{\varLambda} $$ is performed with pp collision data, corresponding to an integrated luminosity of ...3 fb−1, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. An excess of B + → p Λ ¯ $$ {B}^{+}\to p\overline{\varLambda} $$ candidates with respect to background expectations is seen with a statistical significance of 4.1 standard deviations, and constitutes the first evidence for this decay. The branching fraction, measured using the B + → K S 0 π + decay for normalisation, is ℬ B + → p Λ ¯ = 2 . 4 − 0.8 + 1.0 ± 0.3 × 1 0 − 7 , $$ \mathrm{\mathcal{B}}\left({B}^{+}\to p\overline{\varLambda}\right)=\left(2.{4}_{-0.8}^{+1.0}\pm 0.3\right)\times 1{0}^{-7}, $$ where the first uncertainty is statistical and the second systematic.
Abstract The suppressed decay Λ b 0 → pπ − μ + μ −, excluding the J/ψ and ψ(2S) → μ + μ − resonances, is observed for the first time with a significance of 5.5 standard deviations. The analysis is ...performed with proton-proton collision data corresponding to an integrated luminosity of 3 fb−1 collected with the LHCb experiment. The Λ b 0 → pπ − μ + μ − branching fraction is measured relative to the Λ b 0 → J/ψ(→μ + μ −)pπ − branching fraction giving ℬ Λ b 0 → p π − μ + μ − ℬ Λ b 0 → J / ψ → μ + μ − p π − = 0.044 ± 0.012 ± 0.007 , $$ \frac{\mathrm{\mathcal{B}}\left({\Lambda}_b^0\to p{\pi}^{-}{\mu}^{+}{\mu}^{-}\right)}{\mathrm{\mathcal{B}}\left({\Lambda}_b^0\to \mathrm{J}/\psi \left(\to {\mu}^{+}{\mu}^{-}\right)p{\pi}^{-}\right)}=0.044\pm 0.012\pm 0.007, $$ where the first uncertainty is statistical and the second is systematic. This is the first observation of a b → d transition in a baryonic decay.
A time-dependent angular analysis of Bs0→ψ(2S)ϕ decays is performed using data recorded by the LHCb experiment. The data set corresponds to an integrated luminosity of 3.0fb−1 collected during Run 1 ...of the LHC. The CP-violating phase and decay-width difference of the Bs0 system are measured to be ϕs=0.23−0.28+0.29±0.02rad and ΔΓs=0.066−0.044+0.041±0.007ps−1, respectively, where the first uncertainty is statistical and the second systematic. This is the first time that ϕs and ΔΓs have been measured in a decay containing the ψ(2S) resonance.
Abstract A combination of measurements sensitive to the CKM angle γ from LHCb is performed. The inputs are from analyses of time-integrated B + arrow right DK +, B 0 arrow right DK 0, B 0 arrow right ...DK +pi- and B + arrow right DK +pi+pi- tree-level decays. In addition, results from a time-dependent analysis of B s 0 arrow rightD s K ± decays are included. The combination yields γ=(72.2 -7.3 +6.8 )°, where the uncertainty includes systematic effects. The 95.5% confidence level interval is determined to be γ 55.9, 85.2°. A second combination is investigated, also including measurements from B + arrow right Dpi+ and B + arrow right Dpi+pi-pi+ decays, which yields compatible results. Figure not available: see fulltext.
Two new algorithms for use in the analysis of Formula: see text collision are developed to identify the flavour of Formula: see text mesons at production using pions and protons from the ...hadronization process. The algorithms are optimized and calibrated on data, using Formula: see text decays from Formula: see text collision data collected by LHCb at centre-of-mass energies of 7 and 8 TeV . The tagging power of the new pion algorithm is 60% greater than the previously available one; the algorithm using protons to identify the flavour of a Formula: see text meson is the first of its kind.
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