Measurement of ϒ production in pp collisions at √s = 2.76 TeV

The production of ϒ(1S), ϒ(2S) and ϒ(3S) mesons decaying into the dimuon final state is studied with the LHCb detector using a data sample corresponding to an integrated luminosity of 3.3 pb−1 collected in proton–proton collisions at a centre-of-mass energy of √s = 2.76 TeV. The differential production cross-sections times dimuon branching fractions are measured as functions of the ϒ transverse momentum and rapidity, over the ranges pT < 15 GeV/c and 2.0 < y < 4.5. The total cross-sections in this kinematic region, assuming unpolarised production, are measured to be σ (pp → ϒ(1S)X) × B ϒ(1S)→μ+μ− = 1.111 ± 0.043 ± 0.044 nb, σ (pp → ϒ(2S)X) × B ϒ(2S)→μ+μ− = 0.264 ± 0.023 ± 0.011 nb, σ (pp → ϒ(3S)X) × B ϒ(3S)→μ+μ− = 0.159 ± 0.020 ± 0.007 nb, where the first uncertainty is statistical and the second systematic

Impact of clinical phenotypes on management and outcomes in European atrial fibrillation patients: a report from the ESC-EHRA EURObservational Research Programme in AF (EORP-AF) General Long-Term Registry

Background: Epidemiological studies in atrial fibrillation (AF) illustrate that clinical complexity increase the risk of major adverse outcomes. We aimed to describe European AF patients\u2019 clinical phenotypes and analyse the differential clinical course. Methods: We performed a hierarchical cluster analysis based on Ward\u2019s Method and Squared Euclidean Distance using 22 clinical binary variables, identifying the optimal number of clusters. We investigated differences in clinical management, use of healthcare resources and outcomes in a cohort of European AF patients from a Europe-wide observational registry. Results: A total of 9363 were available for this analysis. We identified three clusters: Cluster 1 (n = 3634; 38.8%) characterized by older patients and prevalent non-cardiac comorbidities; Cluster 2 (n = 2774; 29.6%) characterized by younger patients with low prevalence of comorbidities; Cluster 3 (n = 2955;31.6%) characterized by patients\u2019 prevalent cardiovascular risk factors/comorbidities. Over a mean follow-up of 22.5 months, Cluster 3 had the highest rate of cardiovascular events, all-cause death, and the composite outcome (combining the previous two) compared to Cluster 1 and Cluster 2 (all P <.001). An adjusted Cox regression showed that compared to Cluster 2, Cluster 3 (hazard ratio (HR) 2.87, 95% confidence interval (CI) 2.27\u20133.62; HR 3.42, 95%CI 2.72\u20134.31; HR 2.79, 95%CI 2.32\u20133.35), and Cluster 1 (HR 1.88, 95%CI 1.48\u20132.38; HR 2.50, 95%CI 1.98\u20133.15; HR 2.09, 95%CI 1.74\u20132.51) reported a higher risk for the three outcomes respectively. Conclusions: In European AF patients, three main clusters were identified, differentiated by differential presence of comorbidities. Both non-cardiac and cardiac comorbidities clusters were found to be associated with an increased risk of major adverse outcomes

Study of D-(*())(+)(sJ) mesons decaying to D*K-+(S)0 and D*K-0(+) final states

A search is performed for $D^{(*)+}_{sJ}$ mesons in the reactions $pp \to D^{*+} K^0_{\rm S} X$ and $pp \to D^{*0} K^+ X$ using data collected at centre-of-mass energies of 7 and 8 TeV with the LHCb detector. For the $D^{*+} K^0_{\rm S}$ final state, the decays $D^{*+} \to D^0 \pi^+$ with $D^0 \to K^- \pi^+$ and $D^0 \to K^- \pi^+ \pi^+ \pi^-$ are used. For $D^{*0} K^+$, the decay $D^{*0} \to D^0 \pi^0$ with $D^0 \to K^- \pi^+$ is used. A prominent $D_{s1}(2536)^+$ signal is observed in both $D^{*+} K^0_{\rm S}$ and $D^{*0} K^+$ final states. The resonances $D^*_{s1}(2700)^+$ and $D^*_{s3}(2860)^+$ are also observed, yielding information on their properties, including spin-parity assignments. The decay $D^*_{s2}(2573)^+ \to D^{*+} K^0_{\rm S}$ is observed for the first time, at a significance of 6.9 $\sigma$, and its branching fraction relative to the $D^*_{s2}(2573)^+ \to D^+ K^0_{\rm S}$ decay mode is measured

Search for Violations of Lorentz Invariance and CPT Symmetry in B-(s)(0) Mixing

Violations of CPT symmetry and Lorentz invariance are searched for by studying interference effects in B^{0} mixing and in B_{s}^{0} mixing. Samples of B^{0}→J/ψK_{S}^{0} and B_{s}^{0}→J/ψK^{+}K^{-} decays are recorded by the LHCb detector in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3  fb^{-1}. No periodic variations of the particle-antiparticle mass differences are found, consistent with Lorentz invariance and CPT symmetry. Results are expressed in terms of the standard model extension parameter Δa_{μ} with precisions of O(10^{-15}) and O(10^{-14})  GeV for the B^{0} and B_{s}^{0} systems, respectively. With no assumption on Lorentz (non)invariance, the CPT-violating parameter z in the B_{s}^{0} system is measured for the first time and found to be Re(z)=-0.022±0.033±0.005 and Im(z)=0.004±0.011±0.002, where the first uncertainties are statistical and the second systematic

Study of the doubly charmed tetraquark T+cc

Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the D0D0π+ mass spectrum just below the D*+D0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalar T+cc tetraquark with a quark content of ccu⎯⎯⎯d⎯⎯⎯ and spin-parity quantum numbers JP = 1+. Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D*+ mesons is consistent with the observed D0π+ mass distribution. To analyse the mass of the resonance and its coupling to the D*D system, a dedicated model is developed under the assumption of an isoscalar axial-vector T+cc state decaying to the D*D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the T+cc state. In addition, an unexpected dependence of the production rate on track multiplicity is observed

Measurement of the CP Asymmetry in Bs0 - B s0 Mixing

The CP asymmetry in the mixing of Bs0 and Bs0 mesons is measured in proton-proton collision data corresponding to an integrated luminosity of 3.0 fb-1, recorded by the LHCb experiment at center-of-mass energies of 7 and 8 TeV. Semileptonic Bs0 and Bs0 decays are studied in the inclusive mode Ds\u3bc\ub1\u3bd(-)\u3bcX with the Ds mesons reconstructed in the K\u3c0 final state. Correcting the observed charge asymmetry for detection and background effects, the CP asymmetry is found to be asls=(0.39\ub10.26\ub10.20)%, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of asls to date. It is consistent with the prediction from the standard model and will constrain new models of particle physics

A new algorithm for identifying the flavour of B-s(0) mesons at LHCb

A new algorithm for the determination of the initial flavour of B-s(0) mesons is presented. The algorithm is based on two neural networks and exploits the b hadron production mechanism at a hadron collider. The first network is trained to select charged kaons produced in association with the B-s(0) meson. The second network combines the kaon charges to assign the B-s(0) flavour and estimates the probability of a wrong assignment. The algorithm is calibrated using data corresponding to an integrated luminosity of 3 fb(-1) collected by the LHCb experiment in proton-proton collisions at 7 and 8 TeV centre-of-mass energies. The calibration is performed in two ways: by resolving the B-s(0)-B-s(0) flavour oscillations in B-s(0) -> D-s(-)pi(+) decays, and by analysing flavour-specific B-s2*(5840)(0) -> B+K- decays. The tagging power measured in B-s(0) -> D-s(-)pi(+) decays is found to be (1.80 +/- 0.19 ( stat) +/- 0.18 (syst)) which is an improvement of about 50% compared to a similar algorithm previously used in the LHCb experiment

Observation of Lambda(0)(b) -> psi (2S)pK(-) and Lambda(0)(b) -> J/psi pi(+)pi(-)pK(-) decays and a measurement of the A(b)(0) baryon mass

The decays Lambda(0)(b) -> psi(2S)pK(-) and Lambda(0)(b) -> J/psi pi(+)pi(-)pK(-) are observed in a data sample corresponding to an integrated luminosity of 3 fb(-1), collected in proton-proton collisions at 7 and 8 TeV centre-of-mass energies by the LHCb detector. The psi(2S) mesons are reconstructed through the decay modes psi(2S) -> mu(+)mu(-) and psi(2S) -> J/psi pi(+)pi(-) The branching fractions relative to that of Lambda(0)(b) -> J/psi pk(-) are measured to be [GRAPHICS] where the first uncertainties are statistical, the second are systematic and the third is related to the knowledge of J/psi and psi(2S) branching fractions. The mass of the Ai baryon is measured to be M(Lambda(0)(b)) = 5619.65 +/- 0.17 0.17 MeV/c(2), where the uncertainties are statistical and systematic

Model-independent measurement of mixing parameters in D-0 -> K-S(0)pi(+)pi(-) decays

The first model-independent measurement of the charm mixing parameters in the decay D-0 -> K-S(0)pi(+)pi(-) is reported, using a sample of pp collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 1.0 fb(-1) at a centre-of-mass energy of 7 TeV. The measured values are x = (0.86 +/- 0.53 +/- 0.17) x 10(-2), y = (+0.03 +/- 0.46 +/- 0.13) x 10(-2), where the first uncertainties are statistical and include small contributions due to the external input for the strong phase measured by the CLEO collaboration, and the second uncertainties are systematic