Searches for rare B-s(0) and B-0 decays into four muons

Searches for rare $B_s^0$ and $B^0$ decays into four muons are performed using proton-proton collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 $\text{fb}^{-1}$. Direct decays and decays via light scalar and $J/\psi$ resonances are considered. No evidence for the six decays searched for is found and upper limits at the 95% confidence level on their branching fractions ranging between $1.8\times10^{-10}$ and $2.6\times10^{-9}$ are set

First measurement of the Z→μ+μ− angular coefficients in the forward region of pp collisions at √s = 13 TeV

The first study of the angular distribution of μ + μ − pairs produced in the forward rapidity region via the Drell-Yan reaction p p → γ ∗ / Z + X → ℓ + ℓ − + X is presented, using data collected with the LHCb detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.1     fb − 1 . The coefficients of the five leading terms in the angular distribution are determined as a function of the dimuon transverse momentum and rapidity. The results are compared to various theoretical predictions of the Z -boson production mechanism and can also be used to probe transverse-momentum-dependent parton distributions within the proton

Effect of alirocumab on mortality after acute coronary syndromes. An analysis of the ODYSSEY OUTCOMES randomized clinical trial

Background: Previous trials of PCSK9 (proprotein convertase subtilisin-kexin type 9) inhibitors demonstrated reductions in major adverse cardiovascular events, but not death. We assessed the effects of alirocumab on death after index acute coronary syndrome. Methods: ODYSSEY OUTCOMES (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab) was a double-blind, randomized comparison of alirocumab or placebo in 18 924 patients who had an ACS 1 to 12 months previously and elevated atherogenic lipoproteins despite intensive statin therapy. Alirocumab dose was blindly titrated to target achieved low-density lipoprotein cholesterol (LDL-C) between 25 and 50 mg/dL. We examined the effects of treatment on all-cause death and its components, cardiovascular and noncardiovascular death, with log-rank testing. Joint semiparametric models tested associations between nonfatal cardiovascular events and cardiovascular or noncardiovascular death. Results: Median follow-up was 2.8 years. Death occurred in 334 (3.5%) and 392 (4.1%) patients, respectively, in the alirocumab and placebo groups (hazard ratio [HR], 0.85; 95% CI, 0.73 to 0.98; P=0.03, nominal P value). This resulted from nonsignificantly fewer cardiovascular (240 [2.5%] vs 271 [2.9%]; HR, 0.88; 95% CI, 0.74 to 1.05; P=0.15) and noncardiovascular (94 [1.0%] vs 121 [1.3%]; HR, 0.77; 95% CI, 0.59 to 1.01; P=0.06) deaths with alirocumab. In a prespecified analysis of 8242 patients eligible for ≥3 years follow-up, alirocumab reduced death (HR, 0.78; 95% CI, 0.65 to 0.94; P=0.01). Patients with nonfatal cardiovascular events were at increased risk for cardiovascular and noncardiovascular deaths (P<0.0001 for the associations). Alirocumab reduced total nonfatal cardiovascular events (P<0.001) and thereby may have attenuated the number of cardiovascular and noncardiovascular deaths. A post hoc analysis found that, compared to patients with lower LDL-C, patients with baseline LDL-C ≥100 mg/dL (2.59 mmol/L) had a greater absolute risk of death and a larger mortality benefit from alirocumab (HR, 0.71; 95% CI, 0.56 to 0.90; Pinteraction=0.007). In the alirocumab group, all-cause death declined wit h achieved LDL-C at 4 months of treatment, to a level of approximately 30 mg/dL (adjusted P=0.017 for linear trend). Conclusions: Alirocumab added to intensive statin therapy has the potential to reduce death after acute coronary syndrome, particularly if treatment is maintained for ≥3 years, if baseline LDL-C is ≥100 mg/dL, or if achieved LDL-C is low. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01663402

Observation of the Decay Λb0 → Λc+τ−ν¯τ

The first observation of the semileptonic b -baryon decay Λ 0 b → Λ + c τ − ¯ ν τ , with a significance of 6.1 σ , is reported using a data sample corresponding to 3     fb − 1 of integrated luminosity, collected by the LHCb experiment at center-of-mass energies of 7 and 8 TeV at the LHC. The τ − lepton is reconstructed in the hadronic decay to three charged pions. The ratio K = B ( Λ 0 b → Λ + c τ − ¯ ν τ ) / B ( Λ 0 b → Λ + c π − π + π − ) is measured to be 2.46 ± 0.27 ± 0.40 , where the first uncertainty is statistical and the second systematic. The branching fraction B ( Λ 0 b → Λ + c τ − ¯ ν τ ) = ( 1.50 ± 0.16 ± 0.25 ± 0.23 ) % is obtained, where the third uncertainty is from the external branching fraction of the normalization channel Λ 0 b → Λ + c π − π + π − . The ratio of semileptonic branching fractions R ( Λ + c ) ≡ B ( Λ 0 b → Λ + c τ − ¯ ν τ ) / B ( Λ 0 b → Λ + c μ − ¯ ν μ ) is derived to be 0.242 ± 0.026 ± 0.040 ± 0.059 , where the external branching fraction uncertainty from the channel Λ 0 b → Λ + c μ − ¯ ν μ contributes to the last term. This result is in agreement with the standard model prediction

Measurement of chi(c1) (3872) production in proton-proton collisions at root s=8 and 13 TeV

Abstract The production cross-section of the χc1(3872) state relative to the ψ(2S) meson is measured using proton-proton collision data collected with the LHCb experiment at centre-of-mass energies of $$\sqrt{s}$$ s = 8 and 13 TeV, corresponding to integrated luminosities of 2.0 and 5.4 fb−1, respectively. The two mesons are reconstructed in the J/ψπ+π− final state. The ratios of the prompt and nonprompt χc1(3872) to ψ(2S) production cross-sections are measured as a function of transverse momentum, pT, and rapidity, y, of the χc1(3872) and ψ(2S) states, in the kinematic range 4 &lt; pT&lt; 20 GeV/c and 2.0 &lt; y &lt; 4.5. The prompt ratio is found to increase with pT, independently of y. For the prompt component, the double ratio of the χc1(3872) and ψ(2S) production cross-sections between 13 and 8 TeV is observed to be consistent with unity, independent of pT and centre-of-mass energy.</jats:p