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)≡pT(J/ψ)/pT(jet), is measured using jets with pT(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 pT fraction carried by prompt J/ψ mesons in jets at any experiment

Bose-Einstein correlations of same-sign charged pions in the forward region in pp collisions at √s=7 TeV

Bose-Einstein correlations of same-sign charged pions, produced in protonproton collisions at a 7 TeV centre-of-mass energy, are studied using a data sample collected by the LHCb experiment. The signature for Bose-Einstein correlations is observed in the form of an enhancement of pairs of like-sign charged pions with small four-momentum difference squared. The charged-particle multiplicity dependence of the Bose-Einstein correlation parameters describing the correlation strength and the size of the emitting source is investigated, determining both the correlation radius and the chaoticity parameter. The measured correlation radius is found to increase as a function of increasing charged-particle multiplicity, while the chaoticity parameter is seen to decreas

Study of charmonium production in b -hadron decays and first evidence for the decay Bs0

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 byBC ≡ B(b → C X) × B(C → φφ) the inclusive branching fraction of a b hadron to a charmonium state C that decays into a pair of φ mesons, ratios RC1C2 ≡ BC1 /BC2 are determined as Rχc0ηc(1S) = 0.147 ± 0.023 ± 0.011, Rχc1ηc(1S) =0.073 ± 0.016 ± 0.006, Rχc2ηc(1S) = 0.081 ± 0.013 ± 0.005,Rχc1 χc0 = 0.50 ± 0.11 ± 0.01, Rχc2 χc0 = 0.56 ± 0.10 ± 0.01and Rηc(2S)ηc(1S) = 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 χc2(2P) states are obtained as RX(3872)χc1 < 0.34, RX(3915)χc0 < 0.12 andRχc2(2P)χc2 < 0.16. Differential cross-sections as a function of transverse momentum are measured for the ηc(1S) andχc states. The branching fraction of the decay B0s → φφφ is measured for the first time, B(B0s → φφφ) = (2.15±0.54±0.28±0.21B)×10−6. Here the third uncertainty is due to the branching fraction of the decay B0s → φφ, 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 ηc(1S) decays to φφ and p p asB(ηc(1S)→ φφ)/B(ηc(1S)→ p p) = 1.79 ± 0.14 ± 0.32

Measurement of the inelastic pp cross-section at a centre-of-mass energy of 13TeV

The cross-section for inelastic proton-proton collisions at a centre-of-mass energy of 13TeV is measured with the LHCb detector. The fiducial cross-section for inelastic interactions producing at least one prompt long-lived charged particle with momentum p &gt; 2 GeV/c in the pseudorapidity range 2 &lt; η &lt; 5 is determined to be ϭ acc = 62:2 ± 0:2 ± 2:5mb. The first uncertainty is the intrinsic systematic uncertainty of the measurement, the second is due to the uncertainty on the integrated luminosity. The statistical uncertainty is negligible. Extrapolation to full phase space yields the total inelastic proton-proton cross-section ϭ inel = 75:4 ± 3:0 ± 4:5mb, where the first uncertainty is experimental and the second due to the extrapolation. An updated value of the inelastic cross-section at a centre-of-mass energy of 7TeV is also reported

Неспецифические примеси в фармацевтических субстанциях: особенности методик их определения

One of the prerequisites of efficacy and safety of finished pharmaceutical products is the quality of pharmaceutical substances used in their production. Criteria of assessment of pharmaceutical substance purity are determined by the substance composition and production technology, as well as by specific aspects of the finished pharmaceutical product production and use. It is necessary to control the content of nonspecific organic and inorganic impurities, impurities of microbial origin, and residual solvents. The aim of the study was to analyse characteristics of test methods used to determine nonspecific impurities in pharmaceutical substances. The State Pharmacopoeia of the Russian Federation describes various chemical, physical, physicochemical and biological tests for the analysis of nonspecific impurities. Determination of inorganic cations and anions usually includes comparison of test solutions with solutions of the corresponding reference standards, or checking the absence of a positive reaction in the test solution. Quantitative analysis of trace impurities largely relies on highly specific and sensitive test methods, such as atomic absorption spectrometry, atomic emission spectrometry and inductively coupled plasma mass spectrometry. The content of residual organic solvents is determined by gas chromatography or high-performance liquid chromatography. The purity and safety of pharmaceutical substances are ensured by biological tests: “Microbial quality”, “Sterility”, “Pyrogenicity”, “Bacterial endotoxins”. Specific characteristics of test methods used for determination of the content of nonspecific impurities in various pharmaceutical substances depend on physicochemical properties of the tested substances, toxicity of the analysed impurities, and content limits. The results of the study make it possible to formulate a methodological approach to the development of criteria for assessing the quality of pharmaceutical substances. This approach includes mandatory compliance with the basic principles of substance standardisation, as well as case-by-case selection of quality parameters, specific test conditions and content limits for impurities.Одним из факторов эффективности и безопасности готовых лекарственных средств является качество используемых фармацевтических субстанций, критерии оценки чистоты которых обусловлены их составом и технологией получения, а также особенностями производства и применения лекарственных препаратов. Обязательному нормированию подлежат неспецифические примеси органической и неорганической природы, микробного происхождения, остаточные растворители. Цель работы — анализ особенностей методик определения неспецифических примесей в фармацевтических субстанциях. Для оценки их содержания Государственная фармакопея Российской Федерации предусматривает использование различных химических, физических, физико-химических и биологических методов анализа. При определении неорганических катионов и анионов, как правило, проводится сравнение с растворами соответствующих эталонов или фиксируется отсутствие положительной реакции в испытуемом растворе. Для количественного анализа микропримесей достаточно широко используются высокоспецифичные и чувствительные методы: атомно-абсорбционная спектрометрия, атомно-эмиссионная и масс-спектрометрия с индуктивно связанной плазмой. Содержание остаточных органических растворителей определяется методами газовой или высокоэффективной жидкостной хроматографии. Для оценки чистоты и обеспечения безопасности применения фармацевтических субстанций используются биологические испытания: «Микробиологическая чистота», «Стерильность», «Пирогенность», «Бактериальные эндотоксины». Индивидуальные особенности методик проведения испытаний на содержание неспецифических примесей в различных фармацевтических субстанциях обусловлены физико-химическими свойствами исследуемых соединений, токсичностью анализируемых примесей и допустимыми пределами их содержания. Результаты работы позволяют сформулировать методологический подход к разработке критериев оценки качества фармацевтических субстанций, сочетающий обязательное соблюдение основных принципов стандартизации субстанций, индивидуальный выбор показателей качества, особых условий проведения испытаний и норм содержания примесей

Updated Determination of D⁰–D¯⁰Mixing and CP Violation Parameters with D⁰→K⁺π⁻ Decays

We report measurements of charm-mixing parameters based on the decay-time-dependent ratio of D⁰→K⁺π⁻ to D⁰→K⁻π⁺ rates. The analysis uses a data sample of proton-proton collisions corresponding to an integrated luminosity of 5.0  fb⁻¹ recorded by the LHCb experiment from 2011 through 2016. Assuming charge-parity (CP) symmetry, the mixing parameters are determined to be x′²=(3.9±2.7)×10⁻⁵, y′=(5.28±0.52)×10⁻³, and R[subscript D]=(3.454±0.031)×10⁻³. Without this assumption, the measurement is performed separately for D⁰ and D[over ¯]⁰ mesons, yielding a direct CP-violating asymmetry A[subscript D]=(-0.1±9.1)×10⁻³, and magnitude of the ratio of mixing parameters 1.00<|q/p|<1.35 at the 68.3% confidence level. All results include statistical and systematic uncertainties and improve significantly upon previous single-measurement determinations. No evidence for CP violation in charm mixing is observed

Observation of D⁰ Meson Decays to Π⁺π⁻μ⁺μ⁻ and K⁺K⁻μ⁺μ⁻ Final States

The first observation of the D⁰→π⁺π⁻μ⁺μ⁻ and D⁰→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 D⁰→K⁻π⁺[μ⁺μ⁻][subscript ρ⁰/ω], where the two muons are consistent with coming from the decay of a ρ⁰ or ω meson. The results are B(D⁰→π⁺π⁻μ⁺μ⁻)=(9.64±0.48±0.51±0.97)×10⁻⁷ and B(D⁰→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

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[subscript T](J/ψ)/p[subscript T](jet), is measured using jets with p[subscript 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[subscript T] fraction carried by prompt J/ψ mesons in jets at any experiment.National Science Foundation (U.S.

Search for long-lived scalar particles in B + → K + χ ( μ + μ − ) decays

A search for a long-lived scalar particle χ is performed, looking for the decay B[superscript +]→K[superscript +]χ with χ→μ[superscript +]μ[superscript -] in pp collision data corresponding to an integrated luminosity of 3  fb[superscript -1], collected by the LHCb experiment at center-of-mass energies of √s =7 and 8 TeV. This new scalar particle, predicted by hidden sector models, is assumed to have a narrow width. The signal would manifest itself as an excess in the dimuon invariant mass distribution over the Standard Model background. No significant excess is observed in the accessible ranges of mass 250<m(χ)<4700  MeV/c[superscript 2] and lifetime 0.1<τ(χ)<1000  ps. Upper limits on the branching fraction B(B[superscript +]→K[superscript +]χ(μ[superscript +]μ[superscript -])) at 95% confidence level are set as a function of m(χ) and τ(χ), varying between 2×10[superscript -10] and 10[superscript -7]. These are the most stringent limits to date. The limits are interpreted in the context of a model with a light inflaton particle.National Science Foundation (U.S.

Prompt and nonprompt J/ψ production and nuclear modification in pPb collisions at s_NN=8.16 TeV

The production of J/ψ mesons is studied in proton-lead collisions at the centre-of-mass energy per nucleon pair sNN=8.16 TeV with the LHCb detector at the LHC. The double differential cross-sections of prompt and nonprompt J/ψ production are measured as a function of the J/ψ transverse momentum and rapidity in the nucleon–nucleon centre-of-mass frame. Forward-to-backward ratios and nuclear modification factors are determined. The results are compared with theoretical calculations based on collinear factorisation using nuclear parton distribution functions, on the colour glass condensate or on coherent energy loss models.</p