Measurement of J/ψ polarization in pp collisions at [Formula: see text]

An angular analysis of the decay J/ψ→μ+μ- is performed to measure the polarization of prompt J/ψ mesons produced in pp collisions at [Formula: see text]. The dataset corresponds to an integrated luminosity of 0.37 fb-1 collected with the LHCb detector. The measurement is presented as a function of transverse momentum, pT, and rapidity, y, of the J/ψ meson, in the kinematic region 2 Collapse

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Measurement of form-factor-independent observables in the decay B0→K(*0)μ(+)μ(-)

We present a measurement of form-factor-independent angular observables in the decay B(0)→K*(892)(0)μ(+)μ(-). The analysis is based on a data sample corresponding to an integrated luminosity of 1.0 fb(-1), collected by the LHCb experiment in pp collisions at a center-of-mass energy of 7 TeV. Four observables are measured in six bins of the dimuon invariant mass squared q² in the range 0.1<q²<19.0 GeV²/c(4). Agreement with recent theoretical predictions of the standard model is found for 23 of the 24 measurements. A local discrepancy, corresponding to 3.7 Gaussian standard deviations is observed in one q² bin for one of the observables. Considering the 24 measurements as independent, the probability to observe such a discrepancy, or larger, in one is 0.5%.

Observation of the decay B(c)(+) → B(s)(0)π+

The result of a search for the decay B(c)(+) → B(s)(0) π+ is presented, using the B(s)(0) → D(s)(-)π+ and B(s)(0) → J/ψ Ø channels. The analysis is based on a data sample of pp collisions collected with the LHCb detector, corresponding to an integrated luminosity of 1 fb(-1) taken at a center-of-mass energy of 7 TeV, and 2 fb(-1) taken at 8 TeV. The decay B(c)(+) → B(s)(0)π+ is observed with significance in excess of 5 standard deviations independently in both decay channels. The measured product of the ratio of cross sections and branching fraction is [σ(B(c)(+))/σ(B(s)(0))] × B(B(c)(+)→ B(s)(0)π+) = [2.37 ± 0.31 (stat)± 0.11 (syst)(-0.13)(+0.17)(τ(B)(c)(+)))] × 10(-3), in the pseudorapidity range 2<η(B)<5, where the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the B(c)(+) lifetime. This is the first observation of a B meson decaying to another B meson via the weak interaction.

Measurement of the CP asymmetry in B(+)→K(+)μ(+)μ(-) decays

A measurement of the CP asymmetry in B(+)→K(+)μ(+)μ(-) decays is presented using pp collision data, corresponding to an integrated luminosity of 1.0 fb(-1), recorded by the LHCb experiment during 2011 at a center-of-mass energy of 7 TeV. The measurement is performed in seven bins of μ(+)μ(-) invariant mass squared in the range 0.05<q2<22.00 GeV2/c4, excluding the J/ψ and ψ(2S) resonance regions. Production and detection asymmetries are corrected for using the B(+)→J/ψK(+) decay as a control mode. Averaged over all the bins, the CP asymmetry is found to be A(CP)=0.000±0.033 (stat)±0.005 (syst)±0.007 (J/ψK), where the third uncertainty is due to the CP asymmetry of the control mode. This is consistent with the standard model prediction.

Search for the lepton-flavor-violating decays B(s)0→e(±)μ(∓) and B0→e(±)μ(∓)

A search for the lepton-flavor-violating decays B(s)0→e(±)μ(∓) and B0→e(±)μ(∓) is performed with a data sample, corresponding to an integrated luminosity of 1.0 fb(-1) of pp collisions at √s=7 TeV, collected by the LHCb experiment. The observed number of B(s)0→e(±)μ(∓) and B0→e(±)μ(∓) candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(B(s)0→e(±)μ(∓))<1.1(1.4)×10(-8) and B(B0→e(±)μ(∓))<2.8(3.7)×10(-9) at 90% (95%) confidence level (C.L.). These limits are a factor of 20 lower than those set by previous experiments. Lower bounds on the Pati-Salam leptoquark masses are also calculated, M(LQ)(B(s)0→e(±)μ(∓))>101 TeV/c(2) and M(LQ)(B0→e(±)μ(∓))>126 TeV/c(2) at 95% C.L., and are a factor of 2 higher than the previous bounds.

Observation of a resonance in B+ → K+ μ+ μ- decays at low recoil

A broad peaking structure is observed in the dimuon spectrum of B+ → K+ μ+ μ- decays in the kinematic region where the kaon has a low recoil against the dimuon system. The structure is consistent with interference between the B+ → K+ μ+ μ- decay and a resonance and has a statistical significance exceeding six standard deviations. The mean and width of the resonance are measured to be 4191(-8)(+9)  MeV/c2 and 65(-16)(+22)  MeV/c2, respectively, where the uncertainties include statistical and systematic contributions. These measurements are compatible with the properties of the ψ(4160) meson. First observations of both the decay B+ → ψ(4160)K+ and the subsequent decay ψ(4160) → μ+ μ- are reported. The resonant decay and the interference contribution make up 20% of the yield for dimuon masses above 3770  MeV/c2. This contribution is larger than theoretical estimates.

Precision measurement of the Λb(0) baryon lifetime

The ratio of the Λb(0) baryon lifetime to that of the B(0) meson is measured using 1.0  fb(-1) of integrated luminosity in 7 TeV center-of-mass energy pp collisions at the LHC. The Λb(0) baryon is observed for the first time in the decay mode Λb(0)→J/ψpK-, while the B(0) meson decay used is the well known B(0)→J/ψπ+ K- mode, where the π+ K- mass is consistent with that of the K(*0)(892) meson. The ratio of lifetimes is measured to be 0.976±0.012±0.006, in agreement with theoretical expectations based on the heavy quark expansion. Using previous determinations of the B(0) meson lifetime, the Λb(0) lifetime is found to be 1.482±0.018±0.012  ps. In both cases, the first uncertainty is statistical and the second systematic.

Measurement of CP violation in the phase space of B±→K± π+ π- and B±→K± K+ K- decays

The charmless decays B±→K± π+ π- and B±→K± K+ K- are reconstructed using data, corresponding to an integrated luminosity of 1.0  fb(-1), collected by LHCb in 2011. The inclusive charge asymmetries of these modes are measured as ACP(B±→K± π+ π-)=0.032±0.008 (stat)±0.004 (syst)±0.007(J/ψK±) and ACP(B±→K± K+ K-)=-0.043±0.009 (stat)±0.003 (syst)±0.007(J/ψK±), where the third uncertainty is due to the CP asymmetry of the B±→J/ψK± reference mode. The significance of ACP(B±→K± K+ K-) exceeds three standard deviations and is the first evidence of an inclusive CP asymmetry in charmless three-body B decays. In addition to the inclusive CP asymmetries, larger asymmetries are observed in localized regions of phase space.

Measurement of the Bs(0)→μ+ μ- branching fraction and search for B(0)→μ+ μ- decays at the LHCb experiment

A search for the rare decays Bs(0)→μ+ μ- and B(0)→μ+ μ- is performed at the LHCb experiment. The data analyzed correspond to an integrated luminosity of 1  fb(-1) of pp collisions at a center-of-mass energy of 7 TeV and 2  fb(-1) at 8 TeV. An excess of Bs(0)→μ+ μ- signal candidates with respect to the background expectation is seen with a significance of 4.0 standard deviations. A time-integrated branching fraction of B(Bs(0)→μ+ μ-)=(2.9(-1.0)(+1.1))×10(-9) is obtained and an upper limit of B(B(0)→μ+ μ-)<7.4×10(-10) at 95% confidence level is set. These results are consistent with the standard model expectations.

Clinical significance of serum hepcidin-25 levels in predicting invasive fungal disease in patients after transplantation

BACKGROUND

Currently, it is important to identify a good biomarker to predict treatment-related complications in patients with transplantation. This study aimed to evaluate the significance of serum hepcidin-25 in predicting invasive fungal disease (IFD) after transplantation.

PATIENTS AND METHODS

A total of 57 patients who underwent transplantation were included in this study, and their serum samples were obtained and stored at -80°C for analysis. The serum hepcidin-25 were assayed using enzyme-liked immunosorbent assay (ELISA), and hypersensitive C reactive protein (hsCRP) and 1,3-beta-D glucan were measured using standard laboratory techniques. These indices were monitored weekly, from one week before transplantation to four weeks after transplantation.

RESULTS

The median pretransplant serum hepcidin-25 level was 37.00 ng/mL which was higher than that of healthy volunteers (p < 0.001). Because the higher hepcidin-25 level of the third tertile among the patients was 39.855 ng/mL, we set a cutoff level of 40 ng/mL to divide them into low- and high-hepcidin-25 groups (n = 38 and 19, respectively). The prevalences of the documented infection in the two groups were 2.6% and 26%, respectively (p = 0.019). The high-hepcidin-25 group was monitored after transplantation. The hepcidin-25 level peaked one week after transplantation, followed by gradual decrease. The plasma (1-3)-beta-D-glucan reached the summit two week. The proven of IFD was delayed 10 days on average after hepcidin-25 had arrived summit and 5 days after (1-3)-beta-D-glucan peaked.

CONCLUSIONS

 The pretransplant serum hepcidin-25 level would be a useful indicator for predicting the risk of infection after transplantation; and the dynamic changes of hepcidin-25 in patients with high-hepcidin-25 group would help to predict IFD after transplantation.

First measurement of the CP-violating phase in Bs(0) → ϕϕ decays

A first flavor-tagged measurement of the time-dependent CP-violating asymmetry in B(s)(0) → ϕϕ decays is presented. In this decay channel, the CP-violating weak phase arises due to CP violation in the interference between B(s)(0)-B(s)(0) mixing and the b → sss gluonic penguin decay amplitude. Using a sample of pp collision data corresponding to an integrated luminosity of 1.0 fb(-1) and collected at a center-of-mass energy of 7 TeV with the LHCb detector, 880 B(s)(0) → ϕϕ signal decays are obtained. The CP-violating phase is measured to be in the interval [-2.46,-0.76] rad at a 68% confidence level. The p value of the standard model prediction is 16%.

Measurements of the branching fractions of [Formula: see text] decays

The branching fractions of the decay [Formula: see text] for different intermediate states are measured using data, corresponding to an integrated luminosity of 1.0 fb^-1, collected by the LHCb experiment. The total branching fraction, its charmless component [Formula: see text] and the branching fractions via the resonant [Formula: see text] states η_c (1S) and ψ(2S) relative to the decay via a J/ψ intermediate state are [Formula: see text] Upper limits on the B⁺ branching fractions into the η_c (2S) meson and into the charmonium-like states X(3872) and X(3915) are also obtained.

First observation of CP violation in the decays of B(s)0 mesons

Using pp collision data corresponding to an integrated luminosity of 1.0 fb(-1) and collected by LHCb in 2011 at a center-of-mass energy of 7 TeV, we report the measurement of direct CP violation in B(s)(0)→K(-)π(+) decays, A(CP)(B(s)(0)→K(-)π(+)=0.27±0.04 (stat)±0.01 (syst), with significance exceeding 5 standard deviations. This is the first observation of CP violation in the decays of B(s)(0) mesons. Furthermore, we provide an improved determination of direct CP violation in B(0)→K(+)π(-) decays, A(CP)(B(0)→K(+)π(-)=-0.080±0.007 (stat)±0.003 (syst), which is the most precise measurement of this quantity to date.

Determination of the X(3872) meson quantum numbers

The quantum numbers of the X(3872) meson are determined to be J(PC)=1(++) based on angular correlations in B(+)→X(3872)K(+) decays, where X(3872)→π(+)π(-)J/ψ and J/ψ→μ(+)μ(-). The data correspond to 1.0 fb(-1) of pp collisions collected by the LHCb detector. The only alternative assignment allowed by previous measurements J(PC)=2(-+) is rejected with a confidence level equivalent to more than 8 Gaussian standard deviations using a likelihood-ratio test in the full angular phase space. This result favors exotic explanations of the X(3872) state.

Search for rare B(0)((s))→μ(+)μ(-)μ(+)μ(-) decays

A search for the decays B(0)((s))→μ(+)μ(-)μ(+)μ(-) and B(0)→μ(+)μ(-)μ(+)μ(-) is performed using data, corresponding to an integrated luminosity of 1.0 fb(-1), collected with the LHCb detector in 2011. The number of candidates observed is consistent with the expected background and, assuming phase-space models of the decays, limits on the branching fractions are set: B(B(s)(0)→μ(+)μ(-)μ(+)μ(-))<1.6(1.2)×10(-8) and B(B(0)→μ(+)μ(-)μ(+)μ(-))<6.6(5.3)×10(-9) at 95% (90%) confidence level. In addition, limits are set in the context of a supersymmetric model which allows for the B((s))(0) meson to decay into a scalar (S) and pseudoscalar particle (P), where S and P have masses of 2.5 GeV/c and 214.3 MeV/c, respectively, both resonances decay into μ(+)μ(-). The branching fraction limits for these decays are B(B(s)(0)→SP)<1.6(1.2)×10(-8) and B(B(0)→SP)<6.3(5.1)×10(-9) at 95% (90%) confidence level.

Measurement of the forward energy flow in pp collisions at [Formula: see text]

The energy flow created in pp collisions at [Formula: see text] is studied within the pseudorapidity range 1.9<η<4.9 with data collected by the LHCb experiment. The measurements are performed for inclusive minimum-bias interactions, hard scattering processes and events with an enhanced or suppressed diffractive contribution. The results are compared to predictions given by Pythia-based and cosmic-ray event generators, which provide different models of soft hadronic interactions.

Serum biomarkers and the prognosis of AMI patients

BACKGROUND

It has been proven that serum lactate dehydrogenase (LDH) and total bilirubin (TB) increase during acute myocardial infarction (AMI). However, how they influence the prognosis of AMI patients is still not completely known.

METHODS

A total of 239 patients diagnosed with AMI and admitted to the Fourth Clinical Hospital of Harbin Medical University, between 2007 and 2008, were enrolled in this study. All the patients had not undergone primary percutaneous coronary intervention (PCI) because the time window (24 h) was missed. They all underwent PCI 1 week after the onset of symptoms. Serum high-sensitivity C-reactive protein (hs-CRP), TB, LDH, and other biomarkers were determined between 24 and 48 h of symptom onset. All of the patients were followed up for an average of 3.2±0.4 years for occurrence of major adverse cardiac events (MACE).

RESULTS

Patients with MACE had significantly higher levels of hs-CRP, LDH, cystatin C, uric acid, a higher ratio of LDH and TB (LDH/TB), and a lower level of TB: 8.48±3.84 vs. 2.13±1.32 μmol/l, p<0.01; 1,355.8±654.3 vs. 1,151.7±415.4 U/l, p<0.01; 1.69±0.76 vs. 1.00±0.46 mg/l, p<0.01; 419.6±109.2 vs. 343.2±108.2 μmol/l, p<0.01 and 141.1±46.2 vs. 61.2±26.5, p<0.01; 18.3±6.7 vs. 14.8±6.6 mg/l, p<0.01, respectively. In the multivariate COX analysis, LDH, cystatin C, and LDH/TB were significantly associated with the prognosis of these patients.

CONCLUSIONS

Patients under higher oxidative stress tend to have more MACE. LDH, cystatin C, and LDH/TB are strongly related to the prognosis of AMI patients undergoing elective PCI.

Measurement of the Λ(b)(0), Ξ (b)(-), and Ω(b((-) Baryon masses

Bottom baryons decaying to a J/ψ meson and a hyperon are reconstructed using 1.0 fb(-1) of data collected in 2011 with the LHCb detector. Significant Λ(b)(0) → J/ψΛ, Ξ(b((-) → J/ψΞ(-) and Ω(b)(-) → J/ψΩ(-) signals are observed and the corresponding masses are measured to be M(Λ(b)(0))=5619.53 ± 0.13(stat.) ± 0.45(syst.) MeV/c(2), M(Ξ(b)(-)) = 5795.8 ± 0.9(stat.) ± 0.4(syst.) MeV/c(2), M(Ω(b)(-)) = 6046.0 ± 2.2(stat.) ± 0.5(syst.) MeV/c(2) , while the differences with respect to the Λ(b)(0) mass are M(Ξ(b)(-))-M(Λ(b)(0))=176.2 ± 0.9(stat.) ± 0.1(syst.) MeV/c(2), M(Ω(b)(-))-M(Λ(b)(0))=426.4 ± 2.2(stat.) ± 0.4(syst.) MeV/c(2). These are the most precise mass measurements of the Λ(b)(0), Ξ(b)(-) and Ω(b)(-) baryons to date. Averaging the above Λ(b)(0) mass measurement with that published by LHCb using 35 pb(-1) of data collected in 2010 yields M(Λ(b)(0)) = 5619.44 ± 0.13(stat.)± 0.38(syst.) MeV/c(2).

First observation of the decay Bs2*(5840)(0)→B*+ K- and studies of excited Bs(0) mesons

The properties of the orbitally excited (L=1) Bs(0) states are studied by using 1.0  fb(-1) of pp collisions at sqrt[s]=7  TeV collected with the LHCb detector. The first observation of the Bs2*(5840)(0) meson decaying to B*+ K- is reported, and the corresponding branching fraction measured relative to the B+ K- decay mode. The Bs1(5830)(0)→B*+ K- decay is observed as well. The width of the Bs2*(5840)(0) state is measured for the first time, and the masses of the two states are determined with the highest precision to date. The observation of the Bs2*(5840)(0)→B*+ K- decay favors the spin-parity assignment J(P)=2+ for the Bs2*(5840)(0) meson. In addition, the most precise measurement of the mass difference m(B*+)-m(B+)=45.01±0.30(stat)±0.23(syst)  MeV/c(2) is obtained.

Observation of D0-D0 oscillations

We report a measurement of the time-dependent ratio of D(0) → K(+) π- to D(0) → K(-) π(+) decay rates in D(*+)-tagged events using 1.0 fb(-1) of integrated luminosity recorded by the LHCb experiment. We measure the mixing parameters x('2) = (-0.9 ± 1.3) × 10(-4), y' = (7.2 ± 2.4) × 10(-3), and the ratio of doubly-Cabibbo-suppressed to Cabibbo-favored decay rates R(D) = (3.52 ± 0.15) × 10^{-3}, where the uncertainties include statistical and systematic sources. The result excludes the no-mixing hypothesis with a probability corresponding to 9.1 standard deviations and represents the first observation of D0-D0 oscillations from a single measurement.