The difference between the CP asymmetries in the decays Λ c + → pK − K + and Λ c + → pπ − π + i... more The difference between the CP asymmetries in the decays Λ c + → pK − K + and Λ c + → pπ − π + is presented. Proton-proton collision data taken at centre-of-mass energies of 7 and 8 TeV collected by the LHCb detector in 2011 and 2012 are used, corresponding to an integrated luminosity of 3 fb−1. The Λ c + candidates are reconstructed as part of the Λ b 0 → Λ c + μ − X decay chain. In order to maximize the cancellation of production and detection asymmetries in the difference, the final-state kinematic distributions of the two samples are aligned by applying phase-space-dependent weights to the Λ c + → pπ − π + sample. This alters the definition of the integrated CP asymmetry to A CP wgt (pπ − π +). Both samples are corrected for reconstruction and selection efficiencies across the five-dimensional Λ c + decay phase space. The difference in CP asymmetries is found to be $$ \begin{array}{c}\hfill \Delta {A}_{CP}^{\mathrm{wgt}}={A}_{CP}\left(p{K}^{-}{K}^{+}\right) - {A}_{CP}^{\mathr...
The standard model of particle physics currently provides our best description of fundamental par... more The standard model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton–proton collision data collected with the LHCb detector at CERN’s Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the standard model, such as a new fundamental interaction between quarks and leptons.
An angular analysis of the B$^{0}$ → K*$^{0}$e$^{+}$e$^{−}$ decay is performed using a data sampl... more An angular analysis of the B$^{0}$ → K*$^{0}$e$^{+}$e$^{−}$ decay is performed using a data sample corresponding to an integrated luminosity of 9 fb$^{−1}$ of pp collisions collected with the LHCb experiment. The analysis is conducted in the very low dielectron mass squared (q$^{2}$) interval between 0.0008 and 0.257 GeV$^{2}$, where the rate is dominated by the B$^{0}$ → K$^{*0}$γ transition with a virtual photon. The fraction of longitudinal polarisation of the K$^{*0}$ meson, F$_{L}$, is measured to be F$_{L}$ = (4.4 ± 2.6 ± 1.4)%, where the first uncertainty is statistical and the second systematic. The $ {A}_{\mathrm{T}}^{\mathrm{Re}} $ observable, which is related to the lepton forward-backward asymmetry, is measured to be $ {A}_{\mathrm{T}}^{\mathrm{Re}} $ = −0.06 ± 0.08 ± 0.02. The $ {A}_{\mathrm{T}}^{(2)} $ and $ {A}_{\mathrm{T}}^{\mathrm{Im}} $ transverse asymmetries, which are sensitive to the virtual photon polarisation, are found to be $ {A}_{\mathrm{T}}^{(2)} $ = 0.11 ...
A measurement is presented of decay-time-dependent CP violation in the decays B 0 → J/ψ K 0 S and... more A measurement is presented of decay-time-dependent CP violation in the decays B 0 → J/ψ K 0 S and B 0 → ψ(2S)K 0 S , where the J/ψ is reconstructed from two electrons and the ψ(2S) from two muons. The analysis uses a sample of pp collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb −1. The CP-violation observables are measured to be C B 0 → J/ψ K 0 S = 0.12 ± 0.07 ± 0.02 , S B 0 → J/ψ K 0 S = 0.83 ± 0.08 ± 0.01 , C B 0 → ψ(2S)K 0 S = − 0.05 ± 0.10 ± 0.01 , S B 0 → ψ(2S)K 0 S = 0.84 ± 0.10 ± 0.01 , where C describes CP violation in the direct decay, and S describes CP violation in the interference between the amplitudes for the direct decay and for the decay after B 0-B 0 oscillation. The first uncertainties are statistical and the second are systematic. The two sets of results are compatible with the previous LHCb measurement using B 0 → J/ψ K 0 S decays, where the J/ψ meson was reconstructed from two muons. The averages of all three sets of LHCb results are C(B 0 → [cc]K 0 S) = −0.017 ± 0.029 , S(B 0 → [cc]K 0 S) = 0.760 ± 0.034 , under the assumption that higher-order contributions to the decay amplitudes are negligible. The uncertainties include statistical and systematic contributions.
Searches for CP violation in the two-body decays $$ {D}_{(s)}^{+}\to {h}^{+}{\pi}^0 $$ D s + → h ... more Searches for CP violation in the two-body decays $$ {D}_{(s)}^{+}\to {h}^{+}{\pi}^0 $$ D s + → h + π 0 and $$ {D}_{(s)}^{+}\to {h}^{+}\eta $$ D s + → h + η (where h+ denotes a π+ or K+ meson) are performed using pp collision data collected by the LHCb experiment corresponding to either 9 fb−1 or 6 fb−1 of integrated luminosity. The π0 and η mesons are reconstructed using the e+e−γ final state, which can proceed as three-body decays π0→ e+e−γ and η → e+e−γ, or via the two-body decays π0→ γγ and η → γγ followed by a photon conversion. The measurements are made relative to the control modes $$ {D}_{(s)}^{+}\to {K}_{\mathrm{S}}^0{h}^{+} $$ D s + → K S 0 h + to cancel the production and detection asymmetries. The CP asymmetries are measured to be$$ {\displaystyle \begin{array}{c}{\mathcal{A}}_{CP}\left({D}^{+}\to {\pi}^{+}{\pi}^0\right)=\left(-1.3\pm 0.9\pm 0.6\right)\%,\\ {}{\mathcal{A}}_{CP}\left({D}^{+}\to {K}^{+}{\pi}^0\right)=\left(-3.2\pm 4.7\pm 2.1\right)\%,\\ {}\begin{array}{c}{\...
The first full angular analysis of the $$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ B 0 → D ∗ − D s ... more The first full angular analysis of the $$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ B 0 → D ∗ − D s ∗ + decay is performed using 6 fb−1 of pp collision data collected with the LHCb experiment at a centre-of-mass energy of 13 TeV. The $$ {D}_s^{\ast +}\to {D}_s^{+}\gamma $$ D s ∗ + → D s + γ and D*− → $$ {\overline{D}}^0{\pi}^{-} $$ D ¯ 0 π − vector meson decays are used with the subsequent $$ {D}_s^{+} $$ D s + → K+K−π+ and $$ {\overline{D}}^0 $$ D ¯ 0 → K+π− decays. All helicity amplitudes and phases are measured, and the longitudinal polarisation fraction is determined to be fL = 0.578 ± 0.010 ± 0.011 with world-best precision, where the first uncertainty is statistical and the second is systematic. The pattern of helicity amplitude magnitudes is found to align with expectations from quark-helicity conservation in B decays. The ratio of branching fractions [ℬ($$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ B 0 → D ∗ − D s ∗ + ) × ℬ($$ {D}_s^{\ast +}\to {D}_s^{+}\gamma $$ D s ∗ + → D s + γ ...
The decays B+→ J/ψπ+π−K+ are studied using a data set corresponding to an integrated luminosity o... more 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$$ {\displaystyle \begin{array}{c}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\uppsi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi_2(3823)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\upchi}_{\mathrm{c}1}(3872){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\upchi_{\mathrm{c}1}(3872)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}=\left(3.56\pm 0.67\pm 0.11\right)\times {10}^{-2},\\ {}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\uppsi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi_2(3823)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to \uppsi \left(2\mathrm{S}\right){\mathrm{K}}^{+}}\...
Search for the lepton flavour violating decay B + → K + µ − τ + using B * 0 s2 decays The LHCb co... more Search for the lepton flavour violating decay B + → K + µ − τ + using B * 0 s2 decays The LHCb collaboration
The time-dependent CP asymmetries of B0→ π+π− and $$ {B}_s^0 $$ B s 0 → K+K− decays are measured ... more The time-dependent CP asymmetries of B0→ π+π− and $$ {B}_s^0 $$ B s 0 → K+K− decays are measured using a data sample of pp collisions corresponding to an integrated luminosity of 1.9 fb−1, collected with the LHCb detector at a centre-of-mass energy of 13 TeV. The results are$$ {\displaystyle \begin{array}{c}{C}_{\pi \pi}=-0.311\pm 0.045\pm 0.015,\\ {}{S}_{\pi \pi}=-0.706\pm 0.042\pm 0.013,\\ {}{C}_{KK}=0.123\pm 0.034\pm 0.015,\\ {}{S}_{KK}=0.164\pm 0.034\pm 0.014,\\ {}{\mathcal{A}}_{KK}^{\Delta \varGamma }=-0.83\pm 0.05\pm 0.09,\end{array}} $$ C ππ = − 0.311 ± 0.045 ± 0.015 , S ππ = − 0.706 ± 0.042 ± 0.013 , C KK = 0.123 ± 0.034 ± 0.015 , S KK = 0.164 ± 0.034 ± 0.014 , A KK Δ Γ = − 0.83 ± 0.05 ± 0.09 , where the first uncertainties are statistical and the second systematic. The same data sample is used to measure the time-integrated CP asymmetries of B0→ K + π− and $$ {B}_s^0 $$ B s 0 →K−π+ decays and the results are$$ {\displaystyle \begin{array}{c}{A}_{CP}^{B^0}=-0.0824\pm 0.0033\...
The Cabibbo-suppressed semileptonic decay $$ {B}^{+}\to p\overline{p}{\mu}^{+}{\nu}_{\mu } $$ B +... more The Cabibbo-suppressed semileptonic decay $$ {B}^{+}\to p\overline{p}{\mu}^{+}{\nu}_{\mu } $$ B + → p p ¯ μ + ν μ is observed for the first time using a sample of pp collisions corresponding to an integrated luminosity of 1.0, 2.0 and 1.7 fb−1 at centre-of-mass energies of 7, 8 and 13 TeV, respectively. The differential branching fraction is measured as a function of the $$ p\overline{p} $$ p p ¯ invariant mass using the decay mode B+→ J/ψK+ for normalisation. The total branching fraction is measured to be$$ \mathrm{\mathcal{B}}\left({B}^{+}\to p\overline{p}{\mu}^{+}{\nu}_{\mu}\right)=\left({5.27}_{-0.24}^{+0.23}\pm 0.21\pm 0.15\right)\times {10}^{-6}, $$ ℬ B + → p p ¯ μ + ν μ = 5.27 − 0.24 + 0.23 ± 0.21 ± 0.15 × 10 − 6 , where the first uncertainty is statistical, the second systematic and the third is from the uncertainty on the branching fraction of the normalisation channel.
A new baryon state is observed in the Λ 0 b π + π − mass spectrum with high significance using a ... more A new baryon state is observed in the Λ 0 b π + π − mass spectrum with high significance using a data sample of pp collisions, collected with the LHCb detector at centre-of-mass energies √ s = 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb −1. The mass and natural width of the new state are measured to be m = 6072.3 ± 2.9 ± 0.6 ± 0.2 MeV , Γ = 72 ± 11 ± 2 MeV , where the first uncertainty is statistical and the second systematic. The third uncertainty for the mass is due to imprecise knowledge of the Λ 0 b baryon mass. The new state is consistent with the first radial excitation of the Λ 0 b baryon, the Λ b (2S) 0 resonance. Updated measurements of the masses and the upper limits on the natural widths of the previously observed Λ b (5912) 0 and Λ b (5920) 0 states are also reported.
A search for decays of B + c mesons to two charm mesons is performed for the first time using dat... more A search for decays of B + c mesons to two charm mesons is performed for the first time using data corresponding to an integrated luminosity of 3.0 fb −1 , collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8TeV. The decays considered are B + c → D (*)+ (s) D (*)0 and B + c → D (*)+ (s) D (*)0 , which are normalised to high-yield B + → D + (s) D 0 decays. No evidence for a signal is found and limits are set on twelve B + c decay modes.
The cross-sections of $$\psi {(2S)}$$ψ(2S) meson production in proton-proton collisions at $$\sqr... more The cross-sections of $$\psi {(2S)}$$ψ(2S) meson production in proton-proton collisions at $$\sqrt{s} =13\text { TeV} $$s=13TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of $$275\text { pb} ^{-1} $$275pb-1. The production cross-sections for prompt $$\psi {(2S)}$$ψ(2S) mesons and those for $$\psi {(2S)}$$ψ(2S) mesons from b-hadron decays ($${\psi {(2S)}} \text{-from- }{b} $$ψ(2S)-from-b) are determined as functions of the transverse momentum, $$p_{\mathrm {T}}$$pT, and the rapidity, y, of the $$\psi {(2S)}$$ψ(2S) meson in the kinematic range $$2
A search for CP and P violation using triple-product asymmetries is performed with Λ b 0 → pK − ... more A search for CP and P violation using triple-product asymmetries is performed with Λ b 0 → pK − π + π −, Λ b 0 → pK − K + K − and Ξ b 0 → pK − K − π + decays. The data sample corresponds to integrated luminosities of 1.0 fb−1 and 2.0 fb−1, recorded with the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV, respectively. The CP - and P - violating asymmetries are measured both integrating over all phase space and in specific phase-space regions. No significant deviation from CP or P symmetry is found. The first observation of Λ b 0 → pK − χ c0(1P)(→π + π −, K + K −) decay is also reported.
The difference between the CP asymmetries in the decays Λ c + → pK − K + and Λ c + → pπ − π + i... more The difference between the CP asymmetries in the decays Λ c + → pK − K + and Λ c + → pπ − π + is presented. Proton-proton collision data taken at centre-of-mass energies of 7 and 8 TeV collected by the LHCb detector in 2011 and 2012 are used, corresponding to an integrated luminosity of 3 fb−1. The Λ c + candidates are reconstructed as part of the Λ b 0 → Λ c + μ − X decay chain. In order to maximize the cancellation of production and detection asymmetries in the difference, the final-state kinematic distributions of the two samples are aligned by applying phase-space-dependent weights to the Λ c + → pπ − π + sample. This alters the definition of the integrated CP asymmetry to A CP wgt (pπ − π +). Both samples are corrected for reconstruction and selection efficiencies across the five-dimensional Λ c + decay phase space. The difference in CP asymmetries is found to be $$ \begin{array}{c}\hfill \Delta {A}_{CP}^{\mathrm{wgt}}={A}_{CP}\left(p{K}^{-}{K}^{+}\right) - {A}_{CP}^{\mathr...
The standard model of particle physics currently provides our best description of fundamental par... more The standard model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton–proton collision data collected with the LHCb detector at CERN’s Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the standard model, such as a new fundamental interaction between quarks and leptons.
An angular analysis of the B$^{0}$ → K*$^{0}$e$^{+}$e$^{−}$ decay is performed using a data sampl... more An angular analysis of the B$^{0}$ → K*$^{0}$e$^{+}$e$^{−}$ decay is performed using a data sample corresponding to an integrated luminosity of 9 fb$^{−1}$ of pp collisions collected with the LHCb experiment. The analysis is conducted in the very low dielectron mass squared (q$^{2}$) interval between 0.0008 and 0.257 GeV$^{2}$, where the rate is dominated by the B$^{0}$ → K$^{*0}$γ transition with a virtual photon. The fraction of longitudinal polarisation of the K$^{*0}$ meson, F$_{L}$, is measured to be F$_{L}$ = (4.4 ± 2.6 ± 1.4)%, where the first uncertainty is statistical and the second systematic. The $ {A}_{\mathrm{T}}^{\mathrm{Re}} $ observable, which is related to the lepton forward-backward asymmetry, is measured to be $ {A}_{\mathrm{T}}^{\mathrm{Re}} $ = −0.06 ± 0.08 ± 0.02. The $ {A}_{\mathrm{T}}^{(2)} $ and $ {A}_{\mathrm{T}}^{\mathrm{Im}} $ transverse asymmetries, which are sensitive to the virtual photon polarisation, are found to be $ {A}_{\mathrm{T}}^{(2)} $ = 0.11 ...
A measurement is presented of decay-time-dependent CP violation in the decays B 0 → J/ψ K 0 S and... more A measurement is presented of decay-time-dependent CP violation in the decays B 0 → J/ψ K 0 S and B 0 → ψ(2S)K 0 S , where the J/ψ is reconstructed from two electrons and the ψ(2S) from two muons. The analysis uses a sample of pp collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb −1. The CP-violation observables are measured to be C B 0 → J/ψ K 0 S = 0.12 ± 0.07 ± 0.02 , S B 0 → J/ψ K 0 S = 0.83 ± 0.08 ± 0.01 , C B 0 → ψ(2S)K 0 S = − 0.05 ± 0.10 ± 0.01 , S B 0 → ψ(2S)K 0 S = 0.84 ± 0.10 ± 0.01 , where C describes CP violation in the direct decay, and S describes CP violation in the interference between the amplitudes for the direct decay and for the decay after B 0-B 0 oscillation. The first uncertainties are statistical and the second are systematic. The two sets of results are compatible with the previous LHCb measurement using B 0 → J/ψ K 0 S decays, where the J/ψ meson was reconstructed from two muons. The averages of all three sets of LHCb results are C(B 0 → [cc]K 0 S) = −0.017 ± 0.029 , S(B 0 → [cc]K 0 S) = 0.760 ± 0.034 , under the assumption that higher-order contributions to the decay amplitudes are negligible. The uncertainties include statistical and systematic contributions.
Searches for CP violation in the two-body decays $$ {D}_{(s)}^{+}\to {h}^{+}{\pi}^0 $$ D s + → h ... more Searches for CP violation in the two-body decays $$ {D}_{(s)}^{+}\to {h}^{+}{\pi}^0 $$ D s + → h + π 0 and $$ {D}_{(s)}^{+}\to {h}^{+}\eta $$ D s + → h + η (where h+ denotes a π+ or K+ meson) are performed using pp collision data collected by the LHCb experiment corresponding to either 9 fb−1 or 6 fb−1 of integrated luminosity. The π0 and η mesons are reconstructed using the e+e−γ final state, which can proceed as three-body decays π0→ e+e−γ and η → e+e−γ, or via the two-body decays π0→ γγ and η → γγ followed by a photon conversion. The measurements are made relative to the control modes $$ {D}_{(s)}^{+}\to {K}_{\mathrm{S}}^0{h}^{+} $$ D s + → K S 0 h + to cancel the production and detection asymmetries. The CP asymmetries are measured to be$$ {\displaystyle \begin{array}{c}{\mathcal{A}}_{CP}\left({D}^{+}\to {\pi}^{+}{\pi}^0\right)=\left(-1.3\pm 0.9\pm 0.6\right)\%,\\ {}{\mathcal{A}}_{CP}\left({D}^{+}\to {K}^{+}{\pi}^0\right)=\left(-3.2\pm 4.7\pm 2.1\right)\%,\\ {}\begin{array}{c}{\...
The first full angular analysis of the $$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ B 0 → D ∗ − D s ... more The first full angular analysis of the $$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ B 0 → D ∗ − D s ∗ + decay is performed using 6 fb−1 of pp collision data collected with the LHCb experiment at a centre-of-mass energy of 13 TeV. The $$ {D}_s^{\ast +}\to {D}_s^{+}\gamma $$ D s ∗ + → D s + γ and D*− → $$ {\overline{D}}^0{\pi}^{-} $$ D ¯ 0 π − vector meson decays are used with the subsequent $$ {D}_s^{+} $$ D s + → K+K−π+ and $$ {\overline{D}}^0 $$ D ¯ 0 → K+π− decays. All helicity amplitudes and phases are measured, and the longitudinal polarisation fraction is determined to be fL = 0.578 ± 0.010 ± 0.011 with world-best precision, where the first uncertainty is statistical and the second is systematic. The pattern of helicity amplitude magnitudes is found to align with expectations from quark-helicity conservation in B decays. The ratio of branching fractions [ℬ($$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ B 0 → D ∗ − D s ∗ + ) × ℬ($$ {D}_s^{\ast +}\to {D}_s^{+}\gamma $$ D s ∗ + → D s + γ ...
The decays B+→ J/ψπ+π−K+ are studied using a data set corresponding to an integrated luminosity o... more 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$$ {\displaystyle \begin{array}{c}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\uppsi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi_2(3823)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\upchi}_{\mathrm{c}1}(3872){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\upchi_{\mathrm{c}1}(3872)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}=\left(3.56\pm 0.67\pm 0.11\right)\times {10}^{-2},\\ {}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\uppsi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi_2(3823)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to \uppsi \left(2\mathrm{S}\right){\mathrm{K}}^{+}}\...
Search for the lepton flavour violating decay B + → K + µ − τ + using B * 0 s2 decays The LHCb co... more Search for the lepton flavour violating decay B + → K + µ − τ + using B * 0 s2 decays The LHCb collaboration
The time-dependent CP asymmetries of B0→ π+π− and $$ {B}_s^0 $$ B s 0 → K+K− decays are measured ... more The time-dependent CP asymmetries of B0→ π+π− and $$ {B}_s^0 $$ B s 0 → K+K− decays are measured using a data sample of pp collisions corresponding to an integrated luminosity of 1.9 fb−1, collected with the LHCb detector at a centre-of-mass energy of 13 TeV. The results are$$ {\displaystyle \begin{array}{c}{C}_{\pi \pi}=-0.311\pm 0.045\pm 0.015,\\ {}{S}_{\pi \pi}=-0.706\pm 0.042\pm 0.013,\\ {}{C}_{KK}=0.123\pm 0.034\pm 0.015,\\ {}{S}_{KK}=0.164\pm 0.034\pm 0.014,\\ {}{\mathcal{A}}_{KK}^{\Delta \varGamma }=-0.83\pm 0.05\pm 0.09,\end{array}} $$ C ππ = − 0.311 ± 0.045 ± 0.015 , S ππ = − 0.706 ± 0.042 ± 0.013 , C KK = 0.123 ± 0.034 ± 0.015 , S KK = 0.164 ± 0.034 ± 0.014 , A KK Δ Γ = − 0.83 ± 0.05 ± 0.09 , where the first uncertainties are statistical and the second systematic. The same data sample is used to measure the time-integrated CP asymmetries of B0→ K + π− and $$ {B}_s^0 $$ B s 0 →K−π+ decays and the results are$$ {\displaystyle \begin{array}{c}{A}_{CP}^{B^0}=-0.0824\pm 0.0033\...
The Cabibbo-suppressed semileptonic decay $$ {B}^{+}\to p\overline{p}{\mu}^{+}{\nu}_{\mu } $$ B +... more The Cabibbo-suppressed semileptonic decay $$ {B}^{+}\to p\overline{p}{\mu}^{+}{\nu}_{\mu } $$ B + → p p ¯ μ + ν μ is observed for the first time using a sample of pp collisions corresponding to an integrated luminosity of 1.0, 2.0 and 1.7 fb−1 at centre-of-mass energies of 7, 8 and 13 TeV, respectively. The differential branching fraction is measured as a function of the $$ p\overline{p} $$ p p ¯ invariant mass using the decay mode B+→ J/ψK+ for normalisation. The total branching fraction is measured to be$$ \mathrm{\mathcal{B}}\left({B}^{+}\to p\overline{p}{\mu}^{+}{\nu}_{\mu}\right)=\left({5.27}_{-0.24}^{+0.23}\pm 0.21\pm 0.15\right)\times {10}^{-6}, $$ ℬ B + → p p ¯ μ + ν μ = 5.27 − 0.24 + 0.23 ± 0.21 ± 0.15 × 10 − 6 , where the first uncertainty is statistical, the second systematic and the third is from the uncertainty on the branching fraction of the normalisation channel.
A new baryon state is observed in the Λ 0 b π + π − mass spectrum with high significance using a ... more A new baryon state is observed in the Λ 0 b π + π − mass spectrum with high significance using a data sample of pp collisions, collected with the LHCb detector at centre-of-mass energies √ s = 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb −1. The mass and natural width of the new state are measured to be m = 6072.3 ± 2.9 ± 0.6 ± 0.2 MeV , Γ = 72 ± 11 ± 2 MeV , where the first uncertainty is statistical and the second systematic. The third uncertainty for the mass is due to imprecise knowledge of the Λ 0 b baryon mass. The new state is consistent with the first radial excitation of the Λ 0 b baryon, the Λ b (2S) 0 resonance. Updated measurements of the masses and the upper limits on the natural widths of the previously observed Λ b (5912) 0 and Λ b (5920) 0 states are also reported.
A search for decays of B + c mesons to two charm mesons is performed for the first time using dat... more A search for decays of B + c mesons to two charm mesons is performed for the first time using data corresponding to an integrated luminosity of 3.0 fb −1 , collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8TeV. The decays considered are B + c → D (*)+ (s) D (*)0 and B + c → D (*)+ (s) D (*)0 , which are normalised to high-yield B + → D + (s) D 0 decays. No evidence for a signal is found and limits are set on twelve B + c decay modes.
The cross-sections of $$\psi {(2S)}$$ψ(2S) meson production in proton-proton collisions at $$\sqr... more The cross-sections of $$\psi {(2S)}$$ψ(2S) meson production in proton-proton collisions at $$\sqrt{s} =13\text { TeV} $$s=13TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of $$275\text { pb} ^{-1} $$275pb-1. The production cross-sections for prompt $$\psi {(2S)}$$ψ(2S) mesons and those for $$\psi {(2S)}$$ψ(2S) mesons from b-hadron decays ($${\psi {(2S)}} \text{-from- }{b} $$ψ(2S)-from-b) are determined as functions of the transverse momentum, $$p_{\mathrm {T}}$$pT, and the rapidity, y, of the $$\psi {(2S)}$$ψ(2S) meson in the kinematic range $$2
A search for CP and P violation using triple-product asymmetries is performed with Λ b 0 → pK − ... more A search for CP and P violation using triple-product asymmetries is performed with Λ b 0 → pK − π + π −, Λ b 0 → pK − K + K − and Ξ b 0 → pK − K − π + decays. The data sample corresponds to integrated luminosities of 1.0 fb−1 and 2.0 fb−1, recorded with the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV, respectively. The CP - and P - violating asymmetries are measured both integrating over all phase space and in specific phase-space regions. No significant deviation from CP or P symmetry is found. The first observation of Λ b 0 → pK − χ c0(1P)(→π + π −, K + K −) decay is also reported.
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