Measurement of CP Violation in B0→J/ψK{S}^{0} Decays

Measurements are presented of the CP violation observables S and C in the decays of B(0) and Bover ¯]0 mesons to the J/ψK(S)(0) final state. The data sample corresponds to an integrated luminosity of 3.0  fb(-1) collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, and contains a total of 41 560 selected B^{0} and B[over ¯]^{0} decays. The analysis of the time evolution of these decays yields S=0.731±0.035(stat)±0.020(syst) and C=-0.038±0.032(stat)±0.005(syst). In the standard model, S equals sin(2β) to a good level of precision. The values are consistent with the current world averages and with the standard model expectations.

Measurement of the [Formula: see text] production cross-section in proton-proton collisions via the decay [Formula: see text]

The production of the [Formula: see text] state in proton-proton collisions is probed via its decay to the [Formula: see text] final state with the LHCb detector, in the rapidity range [Formula: see text] and in the meson transverse-momentum range [Formula: see text]. The cross-section for prompt production of [Formula: see text] mesons relative to the prompt [Formula: see text] cross-section is measured, for the first time, to be [Formula: see text] at a centre-of-mass energy [Formula: see text] using data corresponding to an integrated luminosity of 0.7 fb[Formula: see text], and [Formula: see text] at [Formula: see text] using 2.0 fb[Formula: see text]. The uncertainties quoted are, in order, statistical, systematic, and that on the ratio of branching fractions of the [Formula: see text] and [Formula: see text] decays to the [Formula: see text] final state. In addition, the inclusive branching fraction of [Formula: see text]-hadron decays into [Formula: see text] mesons is measured, for the first time, to be [Formula: see text], where the third uncertainty includes also the uncertainty on the [Formula: see text] inclusive branching fraction from [Formula: see text]-hadron decays. The difference between the [Formula: see text] and [Formula: see text] meson masses is determined to be [Formula: see text].

Effects of Cohabitation on the Population Performance and Survivorship of the Invasive Mosquito Aedes albopictus and the Resident Mosquito Aedes notoscriptus (Diptera: Culicidae) in Australia

The presence of Aedes albopictus (Skuse) in the Torres Strait of northern Australia increases the potential for colonization and establishment on the mainland. However, there is a possibility that native species that occupy the same habitats may influence the population performance of Ae. albopictus, potentially affecting the establishment of this species in Australia. Cohabitation experiments were performed with the endemic Aedes notoscriptus (Skuse), which has been found occupying the same larval habitats as Ae. albopictus in the Torres Strait and is the most widespread container-inhabiting Aedes species in Australia. The influence of environmental factors and cohabitation between the two species was examined using different climates, food resource levels, food resource types, and species densities. Survivorship proportions and a population performance index (λ') were calculated and compared. The consequences of increased Ae. notoscriptus densities were reduced survivorship and λ' for Ae. albopictus. Despite this, the mean λ' of Ae. albopictus and Ae. notoscriptus was consistently ≥ 1.06, indicating both species could increase under all conditions, potentially due to increasing conspecific densities negatively affecting Ae. notoscriptus. The outcomes from this study suggest that the preexisting presence of Ae. notoscriptus may not prevent the establishment of Ae. albopictus in Australia.

Search for long-lived particles decaying to jet pairs

A search is presented for long-lived particles with a mass between 25 and 50 [Formula: see text] and a lifetime between 1 and 200[Formula: see text] in a sample of proton-proton collisions at a centre-of-mass energy of [Formula: see text] TeV, corresponding to an integrated luminosity of 0.62 [Formula: see text], collected by the LHCb detector. The particles are assumed to be pair-produced by the decay of a standard model-like Higgs boson. The experimental signature of the long-lived particle is a displaced vertex with two associated jets. No excess above the background is observed and limits are set on the production cross-section as a function of the long-lived particle mass and lifetime.

Measurement of Bc+ Production in Proton-Proton Collisions at √[s]=8 TeV

Production of Bc+ mesons in proton-proton collisions at a center-of-mass energy of 8 TeV is studied with data corresponding to an integrated luminosity of 2.0  fb-1 recorded by the LHCb experiment. The ratio of production cross sections times branching fractions between the Bc+→J/ψπ+ and B+→J/ψK+ decays is measured as a function of transverse momentum and rapidity in the regions 0<pT<20  GeV/c and 2.0<y<4.5. The ratio in this kinematic range is measured to be (0.683±0.018±0.009)%, where the first uncertainty is statistical and the second systematic.

Observation of two new Ξ(b)(-) baryon resonances

Two structures are observed close to the kinematic threshold in the Ξ(b)(0)π(-) mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0  fb(-1), recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content bds are expected in this mass region: the spin-parity J(P)=(1/2)(+) and J(P)=(3/2)(+) states, denoted Ξ(b)('-) and Ξ(b)(*-). Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be m(Ξ(b)('-))-m(Ξ(b)(0))-m(π(-))=3.653±0.018±0.006  MeV/c(2), m(Ξ(b)(*-))-m(Ξ(b)(0))-m(π(-))=23.96±0.12±0.06  MeV/c(2), Γ(Ξ(b)(*-))=1.65±0.31±0.10  MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of Γ(Ξ(b)('-))<0.08  MeV at 95% confidence level. Relative production rates of these states are also reported.

Precision measurement of CP violation in B(S)(0)→J/ΨK+K- decays

The time-dependent CP asymmetry in B(s)(0)→J/ψK+K- decays is measured using pp collision data, corresponding to an integrated luminosity of 3.0  fb-1, collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. In a sample of 96,000 B(s)(0)→J/ψK+K- decays, the CP-violating phase ϕs is measured, as well as the decay widths ΓL and ΓH of the light and heavy mass eigenstates of the B(s)(0)-B[over ¯]s0 system. The values obtained are ϕs=-0.058±0.049±0.006  rad, Γs≡(ΓL+ΓH)/2=0.6603±0.0027±0.0015  ps-1, and ΔΓs≡ΓL-ΓH=0.0805±0.0091±0.0032  ps-1, where the first uncertainty is statistical and the second, systematic. These are the most precise single measurements of those quantities to date. A combined analysis with Bs0→J/ψπ+π- decays gives ϕs=-0.010±0.039  rad. All measurements are in agreement with the standard model predictions. For the first time, the phase ϕs is measured independently for each polarization state of the K+K- system and shows no evidence for polarization dependence.

Measurement of the semileptonic CP asymmetry in B0-B[over ¯]0 mixing

The semileptonic CP asymmetry in B0-B[over ¯]0 mixing, a(sl)(d), is measured in proton-proton collision data, corresponding to an integrated luminosity of 3.0  fb-1, recorded by the LHCb experiment. Semileptonic B0 decays are reconstructed in the inclusive final states D-μ+ and D*-μ+, where the D- meson decays into the K+π-π- final state and the D*- meson into the D[over ¯]0(→K+π-)π- final state. The asymmetry between the numbers of D(*)-μ+ and D(*)+μ- decays is measured as a function of the decay time of the B0 mesons. The CP asymmetry is measured to be a(sl)(d)=(-0.02±0.19±0.30)%, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of a(sl)(d) to date and is consistent with the prediction from the standard model.

Precision measurement of the mass and lifetime of the Ξb⁻ baryon

We report on measurements of the mass and lifetime of the Ξ(b)⁻ baryon using about 1800 Ξ(b)⁻ decays reconstructed in a proton-proton collision data set corresponding to an integrated luminosity of 3.0  fb⁻¹ collected by the LHCb experiment. The decays are reconstructed in the Ξ(b)⁻→Ξ(c)⁰π⁻, Ξ(c)⁰→pK⁻K⁻π⁺ channel and the mass and lifetime are measured using the Λ(b)⁰→Λ(c)⁺π⁻ mode as a reference. We measure M(Ξ(b)⁻)-M(Λ(b)⁰)=178.36±0.46±0.16  MeV/c², (τ(Ξ(b)⁻)/τ(Λ(b)⁰)=1.089±0.026±0.011, where the uncertainties are statistical and systematic, respectively. These results lead to a factor of 2 better precision on the Ξ(b)⁻ mass and lifetime compared to previous best measurements, and are consistent with theoretical expectations.

Use of a modified Delphi approach to develop research priorities for the association of coloproctology of Great Britain and Ireland

AIM

The modified Delphi approach is an established method for reaching a consensus opinion among a group of experts in a particular field. We have used this technique to survey the entire membership of the Association of Coloproctology of Great Britain and Ireland (ACPGBI) to reach a consensus on prioritizing clinical research questions in colorectal disease.

METHOD

Three rounds of surveys were conducted using a web-based tool. In the first, the ACPGBI membership was invited to submit research questions. In Rounds 2 and 3 they were asked to score questions on priority. A steering group analysed the results of each round to identify those questions ranked as being of highest priority.

RESULTS

Five hundred and two questions were submitted in Round 1. Following two rounds of voting and analysis, a list of 25 priority questions was produced, including 15 cancer-related and 10 noncancer-related questions.

CONCLUSION

It is anticipated that these results will: (i) set the research agenda over the next few years for the study of colorectal disease in the United Kingdom, (ii) promote development and (iii) define funding of new research and prioritize areas of unmet clinical need where the potential clinical impact is greatest.

Measurement of the CP-violating phase ϕs in Bs(0)→Ds(+)Ds(-) decays

We present a measurement of the CP-violating weak mixing phase ϕs using the decay Bs(0)→Ds(+)Ds(-) in a data sample corresponding to 3.0 fb(-1) of integrated luminosity collected with the LHCb detector in pp collisions at center-of-mass energies of 7 and 8 TeV. An analysis of the time evolution of the system, which does not use the constraint |λ|=1 to allow for the presence of CP violation in decay, yields ϕs=0.02±0.17(stat)±0.02(syst)  rad, |λ|=0.91(-0.15)(+0.18)(stat)±0.02(syst). This result is consistent with the standard model expectation.

Measurement of the B¯s⁰ meson lifetime in Ds⁺π⁻ decays

We present a measurement of the ratio of the B¯s⁰ meson lifetime, in the flavor-specific decay to Ds⁺π⁻, to that of the B¯⁰ meson. The pp collision data used correspond to an integrated luminosity of 1  fb(-1), collected with the LHCb detector, at a center-of-mass energy of 7 TeV. Combining our measured value of 1.010±0.010±0.008 for this ratio with the known B¯⁰ lifetime, we determine the flavor-specific B¯s⁰ lifetime to be τ(B¯s⁰ )=1.535±0.015±0.014  ps, where the uncertainties are statistical and systematic, respectively. This is the most precise measurement to date, and is consistent with previous measurements and theoretical predictions.

Observation of overlapping spin-1 and spin-3 D0K- resonances at mass 2.86 GeV/c2

The resonant substructure of B(s)(0) → D(0)K(-)π(+) decays is studied using a data sample corresponding to an integrated luminosity of 3.0 fb(-1) of pp collision data recorded by the LHCb detector. An excess at m(D(0)K(-))≈ 2.86 GeV/c(2) is found to be an admixture of spin-1 and spin-3 resonances. Therefore, the D(sJ)*(2860)(-) state previously observed in inclusive e(+)e(-) → D(0)K(-)X and pp → D(0)K(-)X processes consists of at least two particles. This is the first observation of a heavy flavored spin-3 resonance, and the first time that any spin-3 particle has been seen to be produced in B decays. The masses and widths of the new states and of the D(s2)*(2573)(-) meson are measured, giving the most precise determinations to date.

Test of lepton universality using b+ → K+ℓ+ℓ- decays

A measurement of the ratio of the branching fractions of the B(+) → K(+)μ(+)μ(-) and B(+) → K(+)e(+)e(-) decays is presented using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb(-1), recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. The value of the ratio of branching fractions for the dilepton invariant mass squared range 1 < q(2) < 6 GeV(2)/c(4) is measured to be 0.745(-0.074)(+0.090)(stat) ± 0.036(syst). This value is the most precise measurement of the ratio of branching fractions to date and is compatible with the standard model prediction within 2.6 standard deviations.

First observation of a baryonic Bc+ decay

A baryonic decay of the B(c)(+) meson, B(c)(+) → J/ψppπ(+), is observed for the first time, with a significance of 7.3 standard deviations, in pp collision data collected with the LHCb detector and corresponding to an integrated luminosity of 3.0 fb(-1) taken at center-of-mass energies of 7 and 8 TeV. With the B(c)(+) → J/ψπ(+) decay as the normalization channel, the ratio of branching fractions is measured to be B(B(c)(+) → J/ψppπ(+))/B(B(c)(+) → J/ψπ(+)) = 0.143(-0.034)(+0.039)(stat) ± 0.013(syst). The mass of the B(c)(+) meson is determined as M(B(c)(+) = 6274.0 ± 1.8(stat) ± 0.4(syst) MeV/c(2), using the B(c)(+) → J/ψppπ(+) channel.

Estimation of force of infection based on different epidemiological proxies: 2009/2010 Influenza epidemic in Malta

Information about infectious disease outbreaks is often gathered indirectly, from doctor's reports and health board records. It also typically underestimates the actual number of cases, but the relationship between the observed proxies and the numbers that drive the diseases is complicated, nonlinear and potentially time- and state-dependent. We use a combination of data collection from the 2009-2010 H1N1 outbreak in Malta, compartmental modelling and Bayesian inference to explore the effect of using various sources of information (consultations, doctor's diagnose, swabbing and molecular testing) on estimation of the effective basic reproduction ratio, R(t). Different proxies and different sampling rates (daily and weekly) lead to similar behaviour of R(t) as the epidemic unfolds, although individual parameters (force of infection, length of latent and infectious period) vary. We also demonstrate that the relationship between different proxies varies as epidemic progresses, with the first period characterised by high ratio of consultations and influenza diagnoses to actual confirmed cases of H1N1. This has important consequences for modelling that is based on reconstructing influenza cases from doctor's reports.

Evidence for CP violation in B+ → ppK+ decays

Three-body B+ → ppK+ and B(+) → ppπ(+) decays are studied using a data sample corresponding to an integrated luminosity of 3.0 fb(-1) collected by the LHCb experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV. Evidence of CP violation in the B(+) → ppK(+) decay is found in regions of the phase space, representing the first measurement of this kind for a final state containing baryons. Measurements of the forward-backward asymmetry of the light meson in the pp rest frame yield A(FB)(ppK(+),m(pp)<2.85 GeV/c(2)) = 0.495 ± 0.012 (stat) ± 0.007 (syst) and A(FB)(ppπ(+),m(pp) <2.85 GeV/c(2)) = -0.409 ± 0.033 (stat) ± 0.006 (syst). In addition, the branching fraction of the decay B(+) → Λ(1520)p is measured to be B(B(+) → Λ(1520)p) = (3.15 ± 0.48 (stat) ± 0.07 (syst) ± 0.26 (BF)) × 10(-7), where BF denotes the uncertainty on secondary branching fractions.

Serotonin in the ventral hippocampus modulates anxiety-like behavior during amphetamine withdrawal

Withdrawal from amphetamine is associated with increased anxiety and sensitivity to stressors which are thought to contribute to relapse. Rats undergoing amphetamine withdrawal fail to exhibit stress-induced increases in serotonin (5-HT) release in the ventral hippocampus and show heightened anxiety-like behaviors. Therefore, we tested the hypothesis that reducing 5-HT levels in the ventral hippocampus is a causal mechanism in increasing anxiety-like behaviors during amphetamine withdrawal. First, we tested whether reducing 5-HT levels in the ventral hippocampus directly increases anxiety behavior. Male rats were bilaterally infused with 5,7-dihydroxytryptamine (5,7-DHT) into the ventral hippocampus, which produced a 83% decrease in ventral hippocampus 5-HT content, and were tested on the elevated plus maze (EPM) for anxiety-like behavior. Reducing ventral hippocampus 5-HT levels decreased the time spent in the open arms of the maze, suggesting that diminished ventral hippocampus 5-HT levels increases anxiety-like behavior. Next, we tested whether increasing 5-HT levels in the ventral hippocampus reverses anxiety behavior exhibited by rats undergoing amphetamine withdrawal. Rats were treated daily with either amphetamine (2.5-mg/kg, i.p.) or saline for 2weeks, and at 2weeks withdrawal, were infused with the selective serotonin reuptake inhibitor paroxetine (0.5μM) bilaterally into the ventral hippocampus and tested for anxiety-like behavior on the EPM. Rats pre-treated with amphetamine exhibited increased anxiety-like behavior on the EPM. This effect was reversed by ventral hippocampus infusion of paroxetine. Our results suggest that 5-HT levels in the ventral hippocampus are critical for regulating anxiety behavior. Increasing 5-HT levels during withdrawal may be an effective strategy for reducing anxiety-induced drug relapse.

First measurement of the charge asymmetry in beauty-quark pair production

The difference in the angular distributions between beauty quarks and antiquarks, referred to as the charge asymmetry, is measured for the first time in bb pair production at a hadron collider. The data used correspond to an integrated luminosity of 1.0 fb(-1) collected at 7 TeV center-of-mass energy in proton-proton collisions with the LHCb detector. The measurement is performed in three regions of the invariant mass of the bb system. The results obtained are A(C)(bb))(40<M(bb))<75 GeV/c(2)) = 0.4 ± 0.4 ± 0.3%, A(C)(bb))(75<M(bb)) < 105 GeV/c(2)) = 2.0 ± 0.9 ± 0.6%, A(C)(bb)(M(bb)) > 105 GeV/c(2)) = 1.6 ± 1.7 ± 0.6%, where A(C)(bb)) is defined as the asymmetry in the difference in rapidity between jets formed from the beauty quark and antiquark, where in each case the first uncertainty is statistical and the second systematic. The beauty jets are required to satisfy 2 < η < 4, E(T) >20 GeV, and have an opening angle in the transverse plane Δ ϕ > 2.6 rad. These measurements are consistent with the predictions of the standard model.

Precision measurement of the mass and lifetime of the Ξ(b)(0) baryon

Using a proton-proton collision data sample corresponding to an integrated luminosity of 3 fb(-1) collected by LHCb at center-of-mass energies of 7 and 8 TeV, about 3800 Ξ(b)(0) → Ξ(c)(+)π(-), Ξ(c)(+)) → pK(-)π(+) signal decays are reconstructed. From this sample, the first measurement of the Ξ(b)(0) baryon lifetime is made, relative to that of the Λ(b)(0) baryon. The mass differences M(Ξ(b)(0))-M(Λ(b)(0)) and M(Ξ(c)(+))-M(Λ(c)(+)) are also measured with precision more than 4 times better than the current world averages. The resulting values are τ(Ξ(b)(0))/τ(Λ)(b)(0)) = 1.006 ± 0.018 ± 0.010,M(Ξ(b)(0))-M(Λ(b)(0)) = 172.44 ± 0.39 ± 0.17 MeV/c(2),M(Ξ(c)(+))-M(Λ(c)(+)) = 181.51 ± 0.14 ± 0.10 MeV/c(2),where the first uncertainty is statistical and the second is systematic. The relative rate of Ξ(b)(0) to Λ(b)(0) baryon production is measured to be f(Ξ)(b)(0))/f(Λ)(b)(0))B(Ξ(b)(0) → Ξ(c)(+)π(-))/B(Λ(b)(0) → Λ(c)(+)π(-))B(Ξ(c)(+) → pK(-)π(+))/B(Λ(c)(+) → pK(-)}π(+)) = (1.88 ± 0.04 ± 0.03) × 10(-2),where the first factor is the ratio of fragmentation fractions, b → Ξ(b)(0) relative to b → Λ(b)(0). Relative production rates as functions of transverse momentum and pseudorapidity are also presented.

Observation of the resonant character of the Z(4430)(-) state

Resonant structures in B^{0}→ψ^{'}π^{-}K^{+} decays are analyzed by performing a four-dimensional fit of the decay amplitude, using pp collision data corresponding to 3  fb^{-1} collected with the LHCb detector. The data cannot be described with K^{+}π^{-} resonances alone, which is confirmed with a model-independent approach. A highly significant Z(4430)^{-}→ψ^{'}π^{-} component is required, thus confirming the existence of this state. The observed evolution of the Z(4430)^{-} amplitude with the ψ^{'}π^{-} mass establishes the resonant nature of this particle. The mass and width measurements are substantially improved. The spin parity is determined unambiguously to be 1^{+}.