Measurement of the Ratio of the B^{0}→D^{*-}τ^{+}ν_{τ} and B^{0}→D^{*-}μ^{+}ν_{μ} Branching Fractions Using Three-Prong τ-Lepton Decays

The ratio of branching fractions R(D^{*-})≡B(B^{0}→D^{*-}τ^{+}ν_{τ})/B(B^{0}→D^{*-}μ^{+}ν_{μ}) is measured using a data sample of proton-proton collisions collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3  fb^{-1}. For the first time, R(D^{*-}) is determined using the τ-lepton decays with three charged pions in the final state. The B^{0}→D^{*-}τ^{+}ν_{τ} yield is normalized to that of the B^{0}→D^{*-}π^{+}π^{-}π^{+} mode, providing a measurement of B(B^{0}→D^{*-}τ^{+}ν_{τ})/B(B^{0}→D^{*-}π^{+}π^{-}π^{+})=1.97±0.13±0.18, where the first uncertainty is statistical and the second systematic. The value of B(B^{0}→D^{*-}τ^{+}ν_{τ})=(1.42±0.094±0.129±0.054)% is obtained, where the third uncertainty is due to the limited knowledge of the branching fraction of the normalization mode. Using the well-measured branching fraction of the B^{0}→D^{*-}μ^{+}ν_{μ} decay, a value of R(D^{*-})=0.291±0.019±0.026±0.013 is established, where the third uncertainty is due to the limited knowledge of the branching fractions of the normalization and B^{0}→D^{*-}μ^{+}ν_{μ} modes. This measurement is in agreement with the standard model prediction and with previous results.

[Comparative analysis of methylation profiles in tissues of oral leukoplakia and oral squamous cell carcinoma]

Objective: To compare the methylation profiles in tissues of oral leukoplakia (OLK) and oral squamous cell carcinoma (OSCC) with healthy tissues of oral mucosa, in order to identify the role of DNA methylation played in tumorigenesis. Methods: DNA samples extracted from tissues of 4 healthy oral mucosa, 4 OSCC and 4 OLK collected from patients of the Department of Oral Medicine, Capital Medical University School of Stomatology were examined and compared using Methylation 450 Bead Chip. The genes associated with differentially methylated CpG sites were selected for gene ontology (GO) analysis and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment. Results: Multiple differentially methylated CpG sites were identified by using the above mentioned assay. Hypermethylation constitutes 86.18% (23 290/27 025) of methylation changes in OLK and hypomethylation accounts for 13.82% (3 734/27 025) of methylation changes. Both hypermethylated and hypomethylated CpG sites were markedly increased in OSCC tissue compared with OLK tissue. The majority of differentially methylated CpG sites were located outside CpG islands, with approximately one-fourth in CpG shores flanking the islands, which were considered highly important for gene regulation and tumorigenesis. Pathway analysis revealed that differentially methylated CpG sites in both OLK and OSCC patients shared the same pathway enrichments, most of which were correlated with carcinogenesis and cancer progression (e.g., DNA repair, cell cycle, and apoptosis). Conclusions: In the present study, methylation-associated alterations affect almost all pathways in the cellular network in both OLK and OSCC. OLK and OSCC shared similar methylation changes whether in pathways or genes, indicating that epigenetically they might have the same molecular basis for disease progression.

Measurement of the Ratio of Branching Fractions B(B_{c}^{+}→J/ψτ^{+}ν_{τ})/B(B_{c}^{+}→J/ψμ^{+}ν_{μ})

A measurement is reported of the ratio of branching fractions R(J/ψ)=B(B_{c}^{+}→J/ψτ^{+}ν_{τ})/B(B_{c}^{+}→J/ψμ^{+}ν_{μ}), where the τ^{+} lepton is identified in the decay mode τ^{+}→μ^{+}ν_{μ}ν[over ¯]_{τ}. This analysis uses a sample of proton-proton collision data corresponding to 3.0  fb^{-1} of integrated luminosity recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. A signal is found for the decay B_{c}^{+}→J/ψτ^{+}ν_{τ} at a significance of 3 standard deviations corrected for systematic uncertainty, and the ratio of the branching fractions is measured to be R(J/ψ)=0.71±0.17(stat)±0.18(syst). This result lies within 2 standard deviations above the range of central values currently predicted by the standard model.

Search for Dark Photons Produced in 13 TeV pp Collisions

Searches are performed for both promptlike and long-lived dark photons, A^{'}, produced in proton-proton collisions at a center-of-mass energy of 13 TeV, using A^{'}→μ^{+}μ^{-} decays and a data sample corresponding to an integrated luminosity of 1.6  fb^{-1} collected with the LHCb detector. The promptlike A^{'} search covers the mass range from near the dimuon threshold up to 70 GeV, while the long-lived A^{'} search is restricted to the low-mass region 214<m(A^{'})<350  MeV. No evidence for a signal is found, and 90% confidence level exclusion limits are placed on the γ-A^{'} kinetic-mixing strength. The constraints placed on promptlike dark photons are the most stringent to date for the mass range 10.6<m(A^{'})<70  GeV, and are comparable to the best existing limits for m(A^{'})<0.5  GeV. The search for long-lived dark photons is the first to achieve sensitivity using a displaced-vertex signature.

NA62 and NA48/2 results on search for Heavy Neutral Leptons

In this paper we present new results on upper limits for the search of Heavy Neutral Leptons (HNL) with data collected by NA48/2 (2003-2004), NA62-RK (2007) and NA62 (2015) CERN experiments. The data collected with different trigger configuration allow to search for both long and short living heavy neutrinos in the mass range below the kaon mass. In addition the status of the search for K+ → π+vv with the NA62 detector will be briefly presented.

First Observation of the Rare Purely Baryonic Decay B^{0}→pp[over ¯]

The first observation of the decay of a B^{0} meson to a purely baryonic final state, B^{0}→pp[over ¯], is reported. The proton-proton collision data sample used was collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponds to an integrated luminosity of 3.0  fb^{-1}. The branching fraction is determined to be B(B^{0}→pp[over ¯])=(1.25±0.27±0.18)×10^{-8}, where the first uncertainty is statistical and the second systematic. The decay mode B^{0}→pp[over ¯] is the rarest decay of the B^{0} meson observed to date. The decay B_{s}^{0}→pp[over ¯] is also investigated. No signal is seen and the upper limit B(B_{s}^{0}→pp[over ¯])<1.5×10^{-8} at 90% confidence level is set on the branching fraction.

χ_{c1} and χ_{c2} Resonance Parameters with the Decays χ_{c1,c2}→J/ψμ^{+}μ^{-}

The decays χ_{c1}→J/ψμ^{+}μ^{-} and χ_{c2}→J/ψμ^{+}μ^{-} are observed and used to study the resonance parameters of the χ_{c1} and χ_{c2} mesons. The masses of these states are measured to be m(χ_{c1})=3510.71±0.04(stat)±0.09(syst)  MeV and m(χ_{c2})=3556.10±0.06(stat)±0.11(syst)  MeV, where the knowledge of the momentum scale for charged particles dominates the systematic uncertainty. The momentum-scale uncertainties largely cancel in the mass difference m(χ_{c2})-m(χ_{c1})=45.39±0.07(stat)±0.03(syst)  MeV. The natural width of the χ_{c2} meson is measured to be Γ(χ_{c2})=2.10±0.20(stat)±0.02(syst)  MeV. These results are in good agreement with and have comparable precision to the current world averages.

Updated search for long-lived particles decaying to jet pairs

A search is presented for long-lived particles with a mass between 25 and 50 GeV / c 2 and a lifetime between 2 and 500 ps, using proton-proton collision data corresponding to an integrated luminosity of 2.0 fb - 1 , collected by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The particles are assumed to be pair-produced in the decay of a 125 GeV / c 2 Standard-Model-like Higgs boson. The experimental signature is a single long-lived particle, identified by a displaced vertex with two associated jets. No excess above background is observed and limits are set on the production cross-section as a function of the mass and lifetime of the long-lived particle.

Observation of D^{0} Meson Decays to π^{+}π^{-}μ^{+}μ^{-} and K^{+}K^{-}μ^{+}μ^{-} Final States

The first observation of the D^{0}→π^{+}π^{-}μ^{+}μ^{-} and D^{0}→K^{+}K^{-}μ^{+}μ^{-} decays is reported using a sample of proton-proton collisions collected by LHCb at a center-of-mass energy of 8 TeV, and corresponding to 2  fb^{-1} of integrated luminosity. The corresponding branching fractions are measured using as normalization the decay D^{0}→K^{-}π^{+}[μ^{+}μ^{-}]_{ρ^{0}/ω}, where the two muons are consistent with coming from the decay of a ρ^{0} or ω meson. The results are B(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(9.64±0.48±0.51±0.97)×10^{-7} and B(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(1.54±0.27±0.09±0.16)×10^{-7}, where the uncertainties are statistical, systematic, and due to the limited knowledge of the normalization branching fraction. The dependence of the branching fraction on the dimuon mass is also investigated.

Search for Baryon-Number Violating Ξ_{b}^{0} Oscillations

A search for baryon-number violating Ξ_{b}^{0} oscillations is performed with a sample of pp collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 3  fb^{-1}. The baryon number at the moment of production is identified by requiring that the Ξ_{b}^{0} come from the decay of a resonance Ξ_{b}^{*-}→Ξ_{b}^{0}π^{-} or Ξ_{b}^{'-}→Ξ_{b}^{0}π^{-}, and the baryon number at the moment of decay is identified from the final state using the decays Ξ_{b}^{0}→Ξ_{c}^{+}π^{-},Ξ_{c}^{+}→pK^{-}π^{+}. No evidence of baryon-number violation is found, and an upper limit at the 95% confidence level is set on the oscillation rate of ω<0.08  ps^{-1}, where ω is the associated angular frequency.

Effects of fish oil-derived fatty acids on suboptimal cardiovascular health: A multicenter, randomized, double-blind, placebo-controlled trial

BACKGROUND AND AIMS

Suboptimal health and metabolic disorders are common in the general population. Both are related to cardiovascular disease. Suboptimal cardiovascular health is defined by the presence of both suboptimal health and metabolic disorders. The aim of the study was to investigate the potential benefit of n-3 long-chain polyunsaturated fatty acids (LCPUFA) in participants with suboptimal cardiovascular health.

METHODS AND RESULTS

A total of 422 participants with suboptimal cardiovascular health, from two clinics in China, were enrolled from September 2014 to April 2015. All the enrolled participants were randomly assigned to receive 4 g/d of fish oil or placebo for three months. Suboptimal health was defined using an accepted questionnaire. Metabolic disorders were defined as one or more abnormalities in blood pressure, fasting plasma glucose, blood lipids, and body mass index (BMI). After treatment, the mean BMI fell significantly more in the n-3 LCPUFA group than in the placebo group (-0.29 ± 0.06 kg/m² vs. -0.02 ± 0.06 kg/m², P = 0.003). Similar results were found in the changes of suboptimal health status and suboptimal cardiovascular health status (P < 0.05 for all). In a multivariate analysis, the n-3 LCPUFA group was 5.44 (1.15, 25.67) times more likely to have optimal cardiovascular health status after treatment.

CONCLUSIONS

n-3 LCPUFA intake improved suboptimal cardiovascular health in this placebo-controlled, randomized, double-blind trial.

TRIAL REGISTRATION

This study is registered at www.clinicaltrials.govNCT02103517.

Improved limit on the branching fraction of the rare decay K S 0 → μ + μ -

A search for the decay K S 0 → μ + μ - is performed, based on a data sample of proton-proton collisions corresponding to an integrated luminosity of 3 fb - 1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV . The observed yield is consistent with the background-only hypothesis, yielding a limit on the branching fraction of B ( K S 0 → μ + μ - ) < 0.8 ( 1.0 ) × 10 - 9 at 90 % ( 95 % ) confidence level. This result improves the previous upper limit on the branching fraction by an order of magnitude.

Custom Repair of Mandibular Bone Defects with 3D Printed Bioceramic Scaffolds

Implanting artificial biomaterial implants into alveolar bone defects with individual shape and appropriate mechanical strength is still a challenge. In this study, bioceramic scaffolds, which can precisely match the mandibular defects in macro and micro, were manufactured by the 3-dimensional (3D) printing technique according to the computed tomography (CT) image. To evaluate the stimulatory effect of the material substrate on bone tissue regeneration in situ in a rabbit mandibular alveolar bone defect model, implants made with the newly developed, mechanically strong ~10% Mg-substituted wollastonite (Ca_90%Mg_10%SiO₃; CSi-Mg10) were fabricated, implanted into the bone defects, and compared with implants made with the typical Ca-phosphate and Ca-silicate porous bioceramics, such as β-tricalcium phosphate (TCP), wollastonite (CaSiO₃; CSi), and bredigite (Bred). The initial physicochemical tests indicated that although the CSi-Mg10 scaffolds had the largest pore dimension, they had the lowest porosity mainly due to the significant linear shrinkage of the scaffolds during sintering. Compared with the sparingly dissolvable TCP scaffolds (~2% weight loss) and superfast dissolvable (in Tris buffer within 6 wk) pure CSi and Bred scaffolds (~12% and ~14% weight loss, respectively), the CSi-Mg10 exhibited a mild in vitro biodissolution and moderate weight loss of ~7%. In addition, the CSi-Mg10 scaffolds showed a considerable initial flexural strength (31 MPa) and maintained very high flexural resistance during soaking in Tris buffer. The in vivo results revealed that the CSi-Mg10 scaffolds have markedly higher osteogenic capability than those on the TCP, CSi, and Bred scaffolds after 16 wk. These results suggest a promising potential application of customized CSi-Mg10 3D robocast scaffolds in the clinic, especially for repair of alveolar bone defects.

[Two-stage total hip arthroplasty using an antibiotic-loaded cement spacer for infected internal fixation of hip fractures]

Objective: To evaluate the application and clinical results of two-stage total hip arthroplasty in the treatment of the deep hip infection following the internal fixation of hip fractures. Methods: From May 2007 to November 2014, 21 patients with active hip infection secondary to internal fixation of hip fractures were treated with two-stage total hip arthroplasty using a temporary antibiotic-loaded cement spacers. Of 21 cases, 15 were males and 6 were females, aged from 27 to 64 years (mean, 45); there are 18 cases of femoral neck fractures and 3 cases of intertrochanteric fractures. The serologic examination and X-ray were taken at 1 month, 3 months, 6 months, 12 months and annually thereafter post-operatively to evaluate the clinical results and prosthesis status. Harris hip score system was used to evaluate the joint function. Results: All patients were successfully treated with two stage operations under general anesthesia. The operational interval was 12-44 weeks (mean, 21) and 1 spacer breakage. For the arthroplasty, cementless components were used in 20 cases and cemented component was use in 1 case. The patients were followed up 25-102 months ( mean, 55 ) and infections were eradicated in all hips. The Harris hip score was improved from 23.24±11.81 pre-operatively to 90.24±3.92 post-operatively and the difference was statistically significant (P<0.05). According to this scoring criteria, the excellent and good rate reached up to 95%. At latest fellow-up, the location of prosthesis were well and the function of hip joint was satisfied. All cases had no dislocation, periprosthetic fracture, ectopic ossification or any other complications at the latest fellow-up. Conclusion: By means of an antibiotic-loaded cement spacer, two-stage total hip arthroplasty is an effective salvage procedure eradicating infection and providing functional improvement to the infected internal fixation of hip fractures. The early and mid-term clinical effects are satisfied.

Observation of the Doubly Charmed Baryon Ξ_{cc}^{++}

A highly significant structure is observed in the Λ_{c}^{+}K^{-}π^{+}π^{+} mass spectrum, where the Λ_{c}^{+} baryon is reconstructed in the decay mode pK^{-}π^{+}. The structure is consistent with originating from a weakly decaying particle, identified as the doubly charmed baryon Ξ_{cc}^{++}. The difference between the masses of the Ξ_{cc}^{++} and Λ_{c}^{+} states is measured to be 1334.94±0.72(stat.)±0.27(syst.)  MeV/c^{2}, and the Ξ_{cc}^{++} mass is then determined to be 3621.40±0.72(stat.)±0.27(syst.)±0.14(Λ_{c}^{+})  MeV/c^{2}, where the last uncertainty is due to the limited knowledge of the Λ_{c}^{+} mass. The state is observed in a sample of proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7  fb^{-1}, and confirmed in an additional sample of data collected at 8 TeV.

Study of charmonium production in b -hadron decays and first evidence for the decay B s 0 → ϕ ϕ ϕ

Using decays to ϕ -meson pairs, the inclusive production of charmonium states in b -hadron decays is studied with pp collision data corresponding to an integrated luminosity of 3.0 fb - 1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. Denoting by B C ≡ B ( b → C X ) × B ( C → ϕ ϕ ) the inclusive branching fraction of a b hadron to a charmonium state C that decays into a pair of ϕ mesons, ratios R C 2 C 1 ≡ B C 1 / B C 2 are determined as R η c ( 1 S ) χ c 0 = 0.147 ± 0.023 ± 0.011 , R η c ( 1 S ) χ c 1 = 0.073 ± 0.016 ± 0.006 , R η c ( 1 S ) χ c 2 = 0.081 ± 0.013 ± 0.005 , R χ c 0 χ c 1 = 0.50 ± 0.11 ± 0.01 , R χ c 0 χ c 2 = 0.56 ± 0.10 ± 0.01 and 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 χ c 2 ( 2 P ) states are obtained as R χ c 1 X ( 3872 ) < 0.34 , R χ c 0 X ( 3915 ) < 0.12 and R χ c 2 χ c 2 ( 2 P ) < 0.16 . Differential cross-sections as a function of transverse momentum are measured for the η c ( 1 S ) and χ c states. The branching fraction of the decay B s 0 → ϕ ϕ ϕ is measured for the first time, 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 s 0 → ϕ ϕ , which is used for normalization. No evidence for intermediate resonances is seen. A preferentially transverse ϕ polarization is observed. The measurements allow the determination of the ratio of the branching fractions for the η c ( 1 S ) decays to ϕ ϕ and p p ¯ as B ( η c ( 1 S ) → ϕ ϕ ) / B ( η c ( 1 S ) → p p ¯ ) = 1.79 ± 0.14 ± 0.32 .

Measurement of B_{s}^{0} and D_{s}^{-} Meson Lifetimes

We report on a measurement of the flavor-specific B_{s}^{0} lifetime and of the D_{s}^{-} lifetime using proton-proton collisions at center-of-mass energies of 7 and 8 TeV, collected by the LHCb experiment and corresponding to 3.0  fb^{-1} of integrated luminosity. Approximately 407 000 B_{s}^{0}→D_{s}^{(*)-}μ^{+}ν_{μ} decays are partially reconstructed in the K^{+}K^{-}π^{-}μ^{+} final state. The B_{s}^{0} and D_{s}^{-} natural widths are determined using, as a reference, kinematically similar B^{0}→D^{(*)-}μ^{+}ν_{μ} decays reconstructed in the same final state. The resulting differences between widths of B_{s}^{0} and B^{0} mesons and of D_{s}^{-} and D^{-} mesons are Δ_{Γ}(B)=-0.0115±0.0053(stat)±0.0041(syst)  ps^{-1} and Δ_{Γ}(D)=1.0131±0.0117(stat)±0.0065(syst)  ps^{-1}, respectively. Combined with the known B^{0} and D^{-} lifetimes, these yield the flavor-specific B_{s}^{0} lifetime, τ_{B_{s}^{0}}^{fs}=1.547±0.013(stat)±0.010(syst)±0.004(τ_{B})  ps and the D_{s}^{-} lifetime, τ_{D_{s}^{-}}=0.5064±0.0030(stat)±0.0017(syst)±0.0017(τ_{D})  ps. The last uncertainties originate from the limited knowledge of the B^{0} and D^{-} lifetimes. The results improve upon current determinations.

Observation of the Decays Λ_{b}^{0}→χ_{c1}pK^{-} and Λ_{b}^{0}→χ_{c2}pK^{-}

The first observation of the decays Λ_{b}^{0}→χ_{c1}pK^{-} and Λ_{b}^{0}→χ_{c2}pK^{-} is reported using a data sample corresponding to an integrated luminosity of 3.0  fb^{-1}, collected by the LHCb experiment in pp collisions at center-of-mass energies of 7 and 8 TeV. The following ratios of branching fractions are measured: B(Λ_{b}^{0}→χ_{c1}pK^{-})/B(Λ_{b}^{0}→J/ψpK^{-})=0.242±0.014±0.013±0.009,B(Λ_{b}^{0}→χ_{c2}pK^{-})/B(Λ_{b}^{0}→J/ψpK^{-})=0.248±0.020±0.014±0.009,B(Λ_{b}^{0}→χ_{c2}pK^{-})/B(Λ_{b}^{0}→χ_{c1}pK^{-})=1.02±0.10±0.02±0.05,where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty on the branching fractions of the χ_{c1}→J/ψγ and χ_{c2}→J/ψγ decays. Using both decay modes, the mass of the Λ_{b}^{0} baryon is also measured to be m_{Λ_{b}^{0}}=5619.44±0.28±0.26  MeV/c^{2}, where the first and second uncertainties are statistical and systematic, respectively.

First Observation of a Baryonic B_{s}^{0} Decay

We report the first observation of a baryonic B_{s}^{0} decay, B_{s}^{0}→pΛ[over ¯]K^{-}, using proton-proton collision data recorded by the LHCb experiment at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3.0  fb^{-1}. The branching fraction is measured to be B(B_{s}^{0}→pΛ[over ¯]K^{-})+B(B_{s}^{0}→p[over ¯]ΛK^{+})=[5.46±0.61±0.57±0.50(B)±0.32(f_{s}/f_{d})]×10^{-6}, where the first uncertainty is statistical and the second systematic, the third uncertainty accounts for the experimental uncertainty on the branching fraction of the B^{0}→pΛ[over ¯]π^{-} decay used for normalization, and the fourth uncertainty relates to the knowledge of the ratio of b-quark hadronization probabilities f_{s}/f_{d}.

Measurement of the CP Violation Parameter A_{Γ} in D^{0}→K^{+}K^{-} and D^{0}→π^{+}π^{-} Decays

Asymmetries in the time-dependent rates of D^{0}→K^{+}K^{-} and D^{0}→π^{+}π^{-} decays are measured in a pp collision data sample collected with the LHCb detector during LHC Run 1, corresponding to an integrated luminosity of 3  fb^{-1}. The asymmetries in effective decay widths between D^{0} and D[over ¯]^{0} decays, sensitive to indirect CP violation, are measured to be A_{Γ}(K^{+}K^{-})=(-0.30±0.32±0.10)×10^{-3} and A_{Γ}(π^{+}π^{-})=(0.46±0.58±0.12)×10^{-3}, where the first uncertainty is statistical and the second systematic. These measurements show no evidence for CP violation and improve on the precision of the previous best measurements by nearly a factor of two.

Search for the Decays B_{s}^{0}→τ^{+}τ^{-} and B^{0}→τ^{+}τ^{-}

A search for the rare decays B_{s}^{0}→τ^{+}τ^{-} and B^{0}→τ^{+}τ^{-} is performed using proton-proton collision data collected with the LHCb detector. The data sample corresponds to an integrated luminosity of 3  fb^{-1} collected in 2011 and 2012. The τ leptons are reconstructed through the decay τ^{-}→π^{-}π^{+}π^{-}ν_{τ}. Assuming no contribution from B^{0}→τ^{+}τ^{-} decays, an upper limit is set on the branching fraction B(B_{s}^{0}→τ^{+}τ^{-})<6.8×10^{-3} at the 95% confidence level. If instead no contribution from B_{s}^{0}→τ^{+}τ^{-} decays is assumed, the limit is B(B^{0}→τ^{+}τ^{-})<2.1×10^{-3} at the 95% confidence level. These results correspond to the first direct limit on B(B_{s}^{0}→τ^{+}τ^{-}) and the world's best limit on B(B^{0}→τ^{+}τ^{-}).

Study of J/ψ Production in Jets

The production of J/ψ mesons in jets is studied in the forward region of proton-proton collisions using data collected with the LHCb detector at a center-of-mass energy of 13 TeV. The fraction of the jet transverse momentum carried by the J/ψ meson, z(J/ψ)≡p_{T}(J/ψ)/p_{T}(jet), is measured using jets with p_{T}(jet)>20  GeV in the pseudorapidity range 2.5<η(jet)<4.0. The observed z(J/ψ) distribution for J/ψ mesons produced in b-hadron decays is consistent with expectations. However, the results for prompt J/ψ production do not agree with predictions based on fixed-order nonrelativistic QCD. This is the first measurement of the p_{T} fraction carried by prompt J/ψ mesons in jets at any experiment.

Measurement of the B_{s}^{0}→μ^{+}μ^{-} Branching Fraction and Effective Lifetime and Search for B^{0}→μ^{+}μ^{-} Decays

A search for the rare decays B_{s}^{0}→μ^{+}μ^{-} and B^{0}→μ^{+}μ^{-} is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4  fb^{-1}. An excess of B_{s}^{0}→μ^{+}μ^{-} decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(B_{s}^{0}→μ^{+}μ^{-})=(3.0±0.6_{-0.2}^{+0.3})×10^{-9}, where the first uncertainty is statistical and the second systematic. The first measurement of the B_{s}^{0}→μ^{+}μ^{-} effective lifetime, τ(B_{s}^{0}→μ^{+}μ^{-})=2.04±0.44±0.05  ps, is reported. No significant excess of B^{0}→μ^{+}μ^{-} decays is found, and a 95% confidence level upper limit, B(B^{0}→μ^{+}μ^{-})<3.4×10^{-10}, is determined. All results are in agreement with the standard model expectations.

Observation of Five New Narrow Ω_{c}^{0} States Decaying to Ξ_{c}^{+}K^{-}

The Ξ_{c}^{+}K^{-} mass spectrum is studied with a sample of pp collision data corresponding to an integrated luminosity of 3.3  fb^{-1}, collected by the LHCb experiment. The Ξ_{c}^{+} is reconstructed in the decay mode pK^{-}π^{+}. Five new, narrow excited Ω_{c}^{0} states are observed: the Ω_{c}(3000)^{0}, Ω_{c}(3050)^{0}, Ω_{c}(3066)^{0}, Ω_{c}(3090)^{0}, and Ω_{c}(3119)^{0}. Measurements of their masses and widths are reported.

Search for massive long-lived particles decaying semileptonically in the LHCb detector

A search is presented for massive long-lived particles decaying into a muon and two quarks. The dataset consists of proton-proton interactions at centre-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of 1 and 2[Formula: see text], respectively. The analysis is performed assuming a set of production mechanisms with simple topologies, including the production of a Higgs-like particle decaying into two long-lived particles. The mass range from 20 to 80 [Formula: see text] and lifetimes from 5 to 100[Formula: see text] are explored. Results are also interpreted in terms of neutralino production in different R-Parity violating supersymmetric models, with masses in the 23-198 GeV/[Formula: see text] range. No excess above the background expectation is observed and upper limits are set on the production cross-section for various points in the parameter space of theoretical models.

The identification of up-regulated ebv-miR-BHRF1-2-5p targeting MALT1 and ebv-miR-BHRF1-3 in the circulation of patients with multiple sclerosis

Epstein-Barr virus (EBV) is a well-documented aetiological factor for multiple sclerosis (MS). EBV encodes at least 44 microRNAs (miRNAs) that are readily detectable in the circulation of human. Previous studies have demonstrated that EBV-encoded miRNAs regulate host immune response and may serve as biomarkers for EBV-associated diseases. However, the roles of EBV miRNAs in MS are still unknown. To fill the gap, we conducted a comprehensive profiling of 44 mature EBV miRNAs in 30 relapsing-remitting MS (RRMS) patients at relapse and 30 matched healthy controls. Expression levels of ebv-miR-BHRF1-2-5p and ebv-miR-BHRF1-3 were elevated significantly in the circulation and correlated positively with the expanded disability status scale (EDSS) scores of MS patients. Receiver operating characteristic (ROC) analyses confirmed that the expression of these two miRNAs distinguished MS patients clearly from healthy controls. Luciferase assays revealed that ebv-miR-BHRF1-2-5p may directly target MALT1 (mucosa-associated lymphoid tissue lymphoma transport protein 1), a key regulator of immune homeostasis. In conclusion, we described the expression of EBV miRNAs in MS and preliminarily validated the potential target genes of significantly altered EBV miRNAs. The findings may pave the way for prospective study about the pathogenesis of MS.

Observation of B_{c}^{+}→D^{0}K^{+} Decays

Using proton-proton collision data corresponding to an integrated luminosity of 3.0  fb^{-1}, recorded by the LHCb detector at center-of-mass energies of 7 and 8 TeV, the B_{c}^{+}→D^{0}K^{+} decay is observed with a statistical significance of 5.1 standard deviations. By normalizing to B^{+}→D[over ¯]^{0}π^{+} decays, a measurement of the branching fraction multiplied by the production rates for B_{c}^{+} relative to B^{+} mesons in the LHCb acceptance is obtained, R_{D^{0}K}=(f_{c}/f_{u})×B(B_{c}^{+}→D^{0}K^{+})=(9.3_{-2.5}^{+2.8}±0.6)×10^{-7}, where the first uncertainty is statistical and the second is systematic. This decay is expected to proceed predominantly through weak annihilation and penguin amplitudes, and is the first B_{c}^{+} decay of this nature to be observed.

Measurement of the phase difference between short- and long-distance amplitudes in the [Formula: see text] decay

A measurement of the phase difference between the short- and long-distance contributions to the [Formula: see text] decay is performed by analysing the dimuon mass distribution. The analysis is based on pp collision data corresponding to an integrated luminosity of 3[Formula: see text] collected by the LHCb experiment in 2011 and 2012. The long-distance contribution to the [Formula: see text] decay is modelled as a sum of relativistic Breit-Wigner amplitudes representing different vector meson resonances decaying to muon pairs, each with their own magnitude and phase. The measured phases of the [Formula: see text] and [Formula: see text] resonances are such that the interference with the short-distance component in dimuon mass regions far from their pole masses is small. In addition, constraints are placed on the Wilson coefficients, [Formula: see text] and [Formula: see text], and the branching fraction of the short-distance component is measured.

Observation of the Annihilation Decay Mode B^{0}→K^{+}K^{-}

A search for the B^{0}→K^{+}K^{-} decay is performed using pp-collision data collected by LHCb. The data set corresponds to integrated luminosities of 1.0 and 2.0  fb^{-1} at center-of-mass energies of 7 and 8 TeV, respectively. This decay is observed for the first time, with a significance of more than 5 standard deviations. The analysis also results in an improved measurement of the branching fraction for the B_{s}^{0}→π^{+}π^{-} decay. The measured branching fractions are B(B^{0}→K^{+}K^{-})=(7.80±1.27±0.81±0.21)×10^{-8} and B(B_{s}^{0}→π^{+}π^{-})=(6.91±0.54±0.63±0.19±0.40)×10^{-7}. The first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the B^{0}→K^{+}π^{-} branching fraction used as a normalization. For the B_{s}^{0} mode, the fourth accounts for the uncertainty on the ratio of the probabilities for b quarks to hadronize into B_{s}^{0} and B^{0} mesons.

Observation of the Decay Ξ_{b}^{-}→pK^{-}K^{-}

Decays of the Ξ_{b}^{-} and Ω_{b}^{-} baryons to the charmless final states ph^{-}h^{'-}, where h^{(')} denotes a kaon or pion, are searched for with the LHCb detector. The analysis is based on a sample of proton-proton collision data collected at center-of-mass energies sqrt[s]=7 and 8 TeV, corresponding to an integrated luminosity of 3  fb^{-1}. The decay Ξ_{b}^{-}→pK^{-}K^{-} is observed with a significance of 8.7 standard deviations, and evidence at the level of 3.4 standard deviations is found for the Ξ_{b}^{-}→pK^{-}π^{-} decay. Results are reported, relative to the B^{-}→K^{+}K^{-}K^{-} normalization channel, for the products of branching fractions and b-hadron production fractions. The branching fractions of Ξ_{b}^{-}→pK^{-}π^{-} and Ξ_{b}^{-}→pπ^{-}π^{-} relative to Ξ_{b}^{-}→pK^{-}K^{-} decays are also measured.

Observation of [Formula: see text] and [Formula: see text] decays

The decays [Formula: see text] and [Formula: see text] are observed for the first time using a data sample corresponding to an integrated luminosity of 3.0 fb[Formula: see text], collected by the LHCb experiment in proton-proton collisions at the centre-of-mass energies of 7 and 8[Formula: see text]. The branching fractions relative to that of [Formula: see text] are measured to be [Formula: see text]where the first uncertainties are statistical and the second are systematic.

Measurement of the b-Quark Production Cross Section in 7 and 13 TeV pp Collisions

Measurements of the cross section for producing b quarks in the reaction pp→bb[over ¯]X are reported in 7 and 13 TeV collisions at the LHC as a function of the pseudorapidity η in the range 2<η<5 covered by the acceptance of the LHCb experiment. The measurements are done using semileptonic decays of b-flavored hadrons decaying into a ground-state charmed hadron in association with a muon. The cross sections in the covered η range are 72.0±0.3±6.8 and 154.3±1.5±14.3  μb for 7 and 13 TeV. The ratio is 2.14±0.02±0.13, where the quoted uncertainties are statistical and systematic, respectively. The agreement with theoretical expectation is good at 7 TeV, but differs somewhat at 13 TeV. The measured ratio of cross sections is larger at lower η than the model prediction.

FGF21 deficiency is associated with childhood obesity, insulin resistance and hypoadiponectinaemia: The BCAMS Study

OBJECTIVE

Fibroblast growth factor 21 (FGF21) exerts beneficial effects on metabolic homoeostasis and has been reported to be regulated by adiponectin, leptin and resistin. However, while an association between increased circulating FGF21 and metabolic disorders has been reported in adults, paediatric-specific data are lacking.

DESIGN AND METHODS

This study investigated the relationship between FGF21 levels and obesity, insulin resistance (IR), the metabolic syndrome (MetS) and adipokines (adiponectin, leptin and resistin) in a cohort of 3231 Chinese youngsters aged 6-18.

RESULTS

There were gender- and puberty-related differences in FGF21 levels. Unexpectedly, FGF21 levels were decreased in children with obesity, and negatively correlated with insulin, HOMA-IR and leptin levels after adjusting for age, gender, puberty and lifestyle factors. Moreover, multiple regression analyses showed that serum FGF21 positively predicted adiponectin levels while resistin positively predicted FGF21 levels independent of BMI (P<0.05). Children in the lowest FGF21 quintile were more likely to have IR (OR: 1.85, 95% CI: 1.41-2.42; P=0.002) and MetS (OR: 1.62, 95% CI: 1.14-2.28; P=0.007) than those in the highest quintile. Further adjusting for BMI and/or the three adipokines modified the association of FGF21 with MetS (P>0.10) but not with IR (P<0.01).

CONCLUSION

Although the associations between adiponectin, leptin, resistin and metabolic abnormalities in our paediatric population were similar to those in adults, correlations of FGF21 levels with obesity, IR and MetS were the inverse of those found in adults. Our present findings suggest that FGF21 deficiency, rather than resistance, contribute to IR and hypoadiponectinaemia independently of obesity in young people.

Observation of J/ψϕ Structures Consistent with Exotic States from Amplitude Analysis of B^{+}→J/ψϕK^{+} Decays

The first full amplitude analysis of B^{+}→J/ψϕK^{+} with J/ψ→μ^{+}μ^{-}, ϕ→K^{+}K^{-} decays is performed with a data sample of 3  fb^{-1} of pp collision data collected at sqrt[s]=7 and 8 TeV with the LHCb detector. The data cannot be described by a model that contains only excited kaon states decaying into ϕK^{+}, and four J/ψϕ structures are observed, each with significance over 5 standard deviations. The quantum numbers of these structures are determined with significance of at least 4 standard deviations. The lightest has mass consistent with, but width much larger than, previous measurements of the claimed X(4140) state.

First Experimental Study of Photon Polarization in Radiative B_{s}^{0} Decays

The polarization of photons produced in radiative B_{s}^{0} decays is studied for the first time. The data are recorded by the LHCb experiment in pp collisions corresponding to an integrated luminosity of 3  fb^{-1} at center-of-mass energies of 7 and 8 TeV. A time-dependent analysis of the B_{s}^{0}→ϕγ decay rate is conducted to determine the parameter A^{Δ}, which is related to the ratio of right- over left-handed photon polarization amplitudes in b→sγ transitions. A value of A^{Δ}=-0.98_{-0.52}^{+0.46}_{-0.20}^{+0.23} is measured. This result is consistent with the standard model prediction within 2 standard deviations.

Successful treatment of very PPROM caused by bipolar cord coagulation in acardiac twin

The authors report management of a woman with an acardiac twin pregnancy complicated by preterm premature rupture of the membrane (PPROM) for more than two months after intrauterine treatment with bipolar cord coagulation at 24 weeks of gestation.

Measurement of CP Violation in B^{0}→D^{+}D^{-} Decays

The CP violation observables S and C in the decay channel B^{0}→D^{+}D^{-} are determined from a sample of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, collected by the LHCb experiment and corresponding to an integrated luminosity of 3  fb^{-1}. The observable S describes CP violation in the interference between mixing and the decay amplitude, and C parametrizes direct CP violation in the decay. The following values are obtained from a flavor-tagged, decay-time-dependent analysis: S=-0.54_{-0.16}^{+0.17}(stat)±0.05(syst), C=0.26_{-0.17}^{+0.18}(stat)±0.02(syst). These values provide evidence for CP violation at a significance level of 4.0 standard deviations. The phase shift due to higher-order standard model corrections is constrained to a small value of Δϕ=-0.16_{-0.21}^{+0.19}  rad.

Search for Higgs-like bosons decaying into long-lived exotic particles

A search is presented for massive long-lived particles, in the 20-60 [Formula: see text] mass range with lifetimes between 5 and 100 [Formula: see text]. The dataset used corresponds to 0.62[Formula: see text] of proton-proton collision data collected by the LHCb detector at [Formula: see text]. The particles are assumed to be pair-produced by the decay of a Higgs-like boson with mass between 80 and 140 [Formula: see text]. No excess above the background expectation is observed and limits are set on the production cross-section as a function of the long-lived particle mass and lifetime and of the Higgs-like boson mass.