1
|
Growth and characterization of W thin films with controlled Ne and Ar contents deposited by bipolar HiPIMS. NUCLEAR MATERIALS AND ENERGY 2021. [DOI: 10.1016/j.nme.2021.101091] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
2
|
Structural and optical properties of amorphous Si-Ge-Te thin films prepared by combinatorial sputtering. Sci Rep 2021; 11:11755. [PMID: 34083613 PMCID: PMC8175571 DOI: 10.1038/s41598-021-91138-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 05/21/2021] [Indexed: 11/29/2022] Open
Abstract
The lack of order in amorphous chalcogenides offers them novel properties but also adds increased challenges in the discovery and design of advanced functional materials. The amorphous compositions in the Si–Ge–Te system are of interest for many applications such as optical data storage, optical sensors and Ovonic threshold switches. But an extended exploration of this system is still missing. In this study, magnetron co-sputtering is used for the combinatorial synthesis of thin film libraries, outside the glass formation domain. Compositional, structural and optical properties are investigated and discussed in the framework of topological constraint theory. The materials in the library are classified as stressed-rigid amorphous networks. The bandgap is heavily influenced by the Te content while the near-IR refractive index dependence on Ge concentration shows a minimum, which could be exploited in applications. A transition from a disordered to a more ordered amorphous network at 60 at% Te, is observed. The thermal stability study shows that the formed crystalline phases are dictated by the concentration of Ge and Te. New amorphous compositions in the Si–Ge–Te system were found and their properties explored, thus enabling an informed and rapid material selection and design for applications.
Collapse
|
3
|
|
4
|
Measurement of J/ ψ polarization in pp collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2013; 73:2631. [PMID: 25814848 PMCID: PMC4370894 DOI: 10.1140/epjc/s10052-013-2631-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 10/15/2013] [Indexed: 05/28/2023]
Abstract
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
|
5
|
Measurement of form-factor-independent observables in the decay B0→K(*0)μ(+)μ(-). PHYSICAL REVIEW LETTERS 2013; 111:191801. [PMID: 24266467 DOI: 10.1103/physrevlett.111.191801] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Indexed: 06/02/2023]
Abstract
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%.
Collapse
|
6
|
Measurement of the CP asymmetry in B(+)→K(+)μ(+)μ(-) decays. PHYSICAL REVIEW LETTERS 2013; 111:151801. [PMID: 24160590 DOI: 10.1103/physrevlett.111.151801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Indexed: 06/02/2023]
Abstract
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.
Collapse
|
7
|
Search for the lepton-flavor-violating decays B(s)0→e(±)μ(∓) and B0→e(±)μ(∓). PHYSICAL REVIEW LETTERS 2013; 111:141801. [PMID: 24138232 DOI: 10.1103/physrevlett.111.141801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Indexed: 06/02/2023]
Abstract
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.
Collapse
|
8
|
Observation of a resonance in B+ → K+ μ+ μ- decays at low recoil. PHYSICAL REVIEW LETTERS 2013; 111:112003. [PMID: 24074076 DOI: 10.1103/physrevlett.111.112003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 08/20/2013] [Indexed: 06/02/2023]
Abstract
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.
Collapse
|
9
|
Precision measurement of the Λb(0) baryon lifetime. PHYSICAL REVIEW LETTERS 2013; 111:102003. [PMID: 25166658 DOI: 10.1103/physrevlett.111.102003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Indexed: 06/03/2023]
Abstract
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.
Collapse
|
10
|
Measurement of CP violation in the phase space of B±→K± π+ π- and B±→K± K+ K- decays. PHYSICAL REVIEW LETTERS 2013; 111:101801. [PMID: 25166651 DOI: 10.1103/physrevlett.111.101801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Indexed: 06/03/2023]
Abstract
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.
Collapse
|
11
|
Measurement of the Bs(0)→μ+ μ- branching fraction and search for B(0)→μ+ μ- decays at the LHCb experiment. PHYSICAL REVIEW LETTERS 2013; 111:101805. [PMID: 25166655 DOI: 10.1103/physrevlett.111.101805] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Indexed: 06/03/2023]
Abstract
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.
Collapse
|
12
|
First measurement of the CP-violating phase in Bs(0) → ϕϕ decays. PHYSICAL REVIEW LETTERS 2013; 110:241802. [PMID: 25165914 DOI: 10.1103/physrevlett.110.241802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Indexed: 06/03/2023]
Abstract
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%.
Collapse
|
13
|
Measurements of the branching fractions of [Formula: see text] decays. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2013; 73:2462. [PMID: 25814862 PMCID: PMC4370952 DOI: 10.1140/epjc/s10052-013-2462-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 05/16/2013] [Indexed: 06/04/2023]
Abstract
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 ηc (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 ηc (2S) meson and into the charmonium-like states X(3872) and X(3915) are also obtained.
Collapse
|
14
|
First observation of CP violation in the decays of B(s)0 mesons. PHYSICAL REVIEW LETTERS 2013; 110:221601. [PMID: 23767711 DOI: 10.1103/physrevlett.110.221601] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Indexed: 06/02/2023]
Abstract
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.
Collapse
|
15
|
Determination of the X(3872) meson quantum numbers. PHYSICAL REVIEW LETTERS 2013; 110:222001. [PMID: 23767712 DOI: 10.1103/physrevlett.110.222001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Indexed: 06/02/2023]
Abstract
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.
Collapse
|
16
|
Search for rare B(0)((s))→μ(+)μ(-)μ(+)μ(-) decays. PHYSICAL REVIEW LETTERS 2013; 110:211801. [PMID: 23745860 DOI: 10.1103/physrevlett.110.211801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Indexed: 06/02/2023]
Abstract
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.
Collapse
|
17
|
Measurement of the forward energy flow in pp collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2013; 73:2421. [PMID: 25814858 PMCID: PMC4370758 DOI: 10.1140/epjc/s10052-013-2421-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 03/22/2013] [Indexed: 05/26/2023]
Abstract
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.
Collapse
|
18
|
Measurement of the Λ(b)(0), Ξ (b)(-), and Ω(b((-) Baryon masses. PHYSICAL REVIEW LETTERS 2013; 110:182001. [PMID: 23683191 DOI: 10.1103/physrevlett.110.182001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Indexed: 06/02/2023]
Abstract
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).
Collapse
|
19
|
First observation of the decay Bs2*(5840)(0)→B*+ K- and studies of excited Bs(0) mesons. PHYSICAL REVIEW LETTERS 2013; 110:151803. [PMID: 25167250 DOI: 10.1103/physrevlett.110.151803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 02/11/2013] [Indexed: 06/03/2023]
Abstract
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.
Collapse
|
20
|
Abstract
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.
Collapse
|
21
|
Measurement of the CP asymmetry in B(0)→K(*0)μ(+)μ(-) decays. PHYSICAL REVIEW LETTERS 2013; 110:031801. [PMID: 23373912 DOI: 10.1103/physrevlett.110.031801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Indexed: 06/01/2023]
Abstract
A measurement of the CP asymmetry in B(0)→K(*0)μ(+)μ(-) decays is presented, based on 1.0 fb(-1) of pp collision data recorded by the LHCb experiment during 2011. The measurement is performed in six bins of invariant mass squared of the μ(+)μ(-) pair, excluding the J/ψ and ψ(2S) resonance regions. Production and detection asymmetries are removed using the B(0)→J/ψK(*0) decay as a control mode. The integrated CP asymmetry is found to be -0.072±0.040(stat)±0.005(syst), consistent with the standard model.
Collapse
|
22
|
First evidence for the decay B(s)(0)→μ+ μ-. PHYSICAL REVIEW LETTERS 2013; 110:021801. [PMID: 23383888 DOI: 10.1103/physrevlett.110.021801] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Indexed: 06/01/2023]
Abstract
A search for the rare decays B(s)(0)→μ+ μ- and B(0)→μ+ μ- is performed with data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise 1.1 fb(-1) of proton-proton collisions at sqrt[s]=8 TeV and 1.0 fb(-1) at sqrt[s]=7 TeV. We observe an excess of B(s)(0)→μ+ μ- candidates with respect to the background expectation. The probability that the background could produce such an excess or larger is 5.3×10(-4) corresponding to a signal significance of 3.5 standard deviations. A maximum-likelihood fit gives a branching fraction of B(B(s)(0)→μ+ μ-)=(3.2(-1.2)(+1.5))×10(-9), where the statistical uncertainty is 95% of the total uncertainty. This result is in agreement with the standard model expectation. The observed number of B(0)→μ+ μ- candidates is consistent with the background expectation, giving an upper limit of B(B(0)→μ+ μ-)<9.4×10(-10) at 95% confidence level.
Collapse
|
23
|
Measurements of B(c)+ production and mass with the B(c)+ → J/ψπ+ decay. PHYSICAL REVIEW LETTERS 2012; 109:232001. [PMID: 23368183 DOI: 10.1103/physrevlett.109.232001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Indexed: 06/01/2023]
Abstract
Measurements of B(c)(+) production and mass are performed with the decay mode B(c)(+)→J/ψπ(+) using 0.37 fb(-1) of data collected in pp collisions at √[s]=7 TeV by the LHCb experiment. The ratio of the production cross section times branching fraction between the B(c)(+)→J/ψπ(+) and the B(+)→J/ψK(+) decays is measured to be (0.68±0.10(stat)±0.03(syst)±0.05(lifetime))% for B(c)(+) and B(+) mesons with transverse momenta p(T)>4 GeV/c and pseudorapidities 2.5<η<4.5. The B(c)(+) mass is directly measured to be 6273.7±1.3(stat)±1.6(syst) MeV/c(2), and the measured mass difference with respect to the B(+) meson is M(B(c)(+))-M(B(+))=994.6±1.3(stat)±0.6(syst) MeV/c(2).
Collapse
|
24
|
Abstract
Using pp collision data corresponding to 1.0 fb(-1) integrated luminosity collected by the LHCb detector, two narrow states are observed in the Λ(b)(0)π(+)π(-) spectrum with masses 5911.97±0.12(stat)±0.02(syst)±0.66(Λ(b)(0) mass) MeV/c(2) and 5919.77±0.08(stat)±0.02(syst)±0.66(Λ(b)(0) mass) MeV/c(2). The significances of the observations are 5.2 and 10.2 standard deviations, respectively. These states are interpreted as the orbitally excited Λ(b)(0) baryons, Λ(b)(*0)(5912) and Λ(b)(*0)(5920).
Collapse
|
25
|
Measurement of the B¯(s)(0) effective lifetime in the J/ψf0(980) final state. PHYSICAL REVIEW LETTERS 2012; 109:152002. [PMID: 23102295 DOI: 10.1103/physrevlett.109.152002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Indexed: 06/01/2023]
Abstract
The effective lifetime of the B ¯(s)(0) meson in the decay mode B¯(s)(0)→J/ψf(0)(980) is measured using 1.0 fb(-1) of data collected in pp collisions at √s=7 TeV with the LHCb detector. The result is 1.700±0.040±0.026 ps, where the first uncertainty is statistical and the second systematic. As the final state is CP-odd, and CP violation in this mode is measured to be small, the lifetime measurement can be translated into a measurement of the decay width of the heavy B¯(s)(0) mass eigenstate, Γ(H)=0.588±0.014±0.009 ps(-1).
Collapse
|
26
|
Observation of B0→D¯(0)K(+)K(-) and evidence for B(s)(0)→D¯(0)K(+)K(-). PHYSICAL REVIEW LETTERS 2012; 109:131801. [PMID: 23030081 DOI: 10.1103/physrevlett.109.131801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Indexed: 06/01/2023]
Abstract
The first observation of the decay B0→D¯(0)K(+)K(-) is reported from an analysis of 0.62 fb(-1) of pp collision data collected with the LHCb detector. Its branching fraction is measured relative to that of the topologically similar decay B(0)→D ¯(0)π(+)π(-) to be (B(B(0)→D¯(0)K(+)K(-))/B(B(0)→D¯(0)π(+)π(-))=0.056±0.011±0.007,where the first uncertainty is statistical and the second is systematic. The significance of the signal is 5.8σ. Evidence, with 3.8σ significance, for B(s)(0)→D¯(0)K(+)K(-) decays is also presented. The relative branching fraction is measured to be B(B(s)(0)→D¯(0)K(+)K(-))/B(B(0)→D¯(0)K(+)K(-))=0.90±0.27±0.20. These channels are of interest to study the mechanisms behind hadronic B decays, and open new possibilities for CP violation analyses with larger data sets.
Collapse
|
27
|
Measurement of relative branching fractions of B decays to ψ(2 S) and J/ ψ mesons. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2012; 72:2118. [PMID: 25814846 PMCID: PMC4370872 DOI: 10.1140/epjc/s10052-012-2118-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 07/06/2012] [Indexed: 06/04/2023]
Abstract
The relative rates of B-meson decays into J/ψ and ψ(2S) mesons are measured for the three decay modes in pp collisions recorded with the LHCb detector. The ratios of branching fractions ([Formula: see text]) are measured to be [Formula: see text] where the third uncertainty is from the ratio of the ψ(2S) and J/ψ branching fractions to μ+μ-.
Collapse
|
28
|
Measurement of ψ(2 S) meson production in pp collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2012; 72:2100. [PMID: 25814845 PMCID: PMC4370818 DOI: 10.1140/epjc/s10052-012-2100-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 05/22/2012] [Indexed: 05/28/2023]
Abstract
The differential cross-section for the inclusive production of ψ(2S) mesons in pp collisions at [Formula: see text] has been measured with the LHCb detector. The data sample corresponds to an integrated luminosity of 36 pb-1. The ψ(2S) mesons are reconstructed in the decay channels ψ(2S)→μ+μ- and ψ(2S)→J/ψπ+π-, with the J/ψ meson decaying into two muons. Results are presented both for promptly produced ψ(2S) mesons and for those originating from b-hadron decays. In the kinematic range pT(ψ(2S))≤16 GeV/c and 2<y(ψ(2S))≤4.5 we measure [Formula: see text] where the last uncertainty on the prompt cross-section is due to the unknown ψ(2S) polarization. Recent QCD calculations are found to be in good agreement with our measurements. Combining the present result with the LHCb J/ψ measurements we determine the inclusive branching fraction [Formula: see text] where the last uncertainty is due to the [Formula: see text], [Formula: see text] and [Formula: see text] branching fraction uncertainties.
Collapse
|
29
|
First observation of the decay B(c)+ → J/ψπ(+) π- π+. PHYSICAL REVIEW LETTERS 2012; 108:251802. [PMID: 23004586 DOI: 10.1103/physrevlett.108.251802] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Indexed: 06/01/2023]
Abstract
The decay B(c)(+) → J/ψπ(+) π(-) π(+) is observed for the first time, using 0.8 fb(-1) of pp collisions at sqrt[s] = 7 TeV collected by the LHCb experiment. The ratio of branching fractions B(B(c)(+) → J/ψπ(+) π(-) π(+))/B(B(c)(+)→J/ψπ^{+}) is measured to be 2.41 ± 0.30 ± 0.33, where the first uncertainty is statistical and the second is systematic. The result is in agreement with theoretical predictions.
Collapse
|
30
|
Determination of the sign of the decay width difference in the B(s)(0) system. PHYSICAL REVIEW LETTERS 2012; 108:241801. [PMID: 23004259 DOI: 10.1103/physrevlett.108.241801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Indexed: 06/01/2023]
Abstract
The interference between the K+ K- S-wave and P-wave amplitudes in B(s)(0) → J/ψK+ K- decays with the K+ K- pairs in the region around the ϕ(1020) resonance is used to determine the variation of the difference of the strong phase between these amplitudes as a function of K+ K- invariant mass. Combined with the results from our CP asymmetry measurement in B(s)(0) → J/ψϕ decays, we conclude that the B(s)(0) mass eigenstate that is almost CP = +1 is lighter and decays faster than the mass eigenstate that is almost CP = -1. This determines the sign of the decay width difference ΔΓ(s) ≡ Γ(L) - Γ(H) to be positive. Our result also resolves the ambiguity in the past measurements of the CP violating phase ϕ(s) to be close to zero rather than π. These conclusions are in agreement with the standard model expectations.
Collapse
|
31
|
Strong constraints on the rare decays B(s)(0) → μ+ μ- and B0 → μ+ μ-. PHYSICAL REVIEW LETTERS 2012; 108:231801. [PMID: 23003947 DOI: 10.1103/physrevlett.108.231801] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Indexed: 06/01/2023]
Abstract
A search for B(s)(0) → μ+ μ- and B0 → μ+ μ decays is performed using 1.0 fb(-1) of pp collision data collected at sqrt[s] = 7 TeV with the LHCb experiment at the Large Hadron Collider. For both decays, the number of observed events is consistent with expectation from background and standard model signal predictions. Upper limits on the branching fractions are determined to be B(B(s)(0) → μ+ μ-) < 4.5(3.8)×10(-9) and B(B0 → μ+ μ-) < 1.0(0.81)×10(-9) at 95% (90%) confidence level.
Collapse
|
32
|
Opposite-side flavour tagging of B mesons at the LHCb experiment. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2012; 72:2022. [PMID: 25814835 PMCID: PMC4371096 DOI: 10.1140/epjc/s10052-012-2022-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 04/26/2012] [Indexed: 05/28/2023]
Abstract
The calibration and performance of the opposite-side flavour tagging algorithms used for the measurements of time-dependent asymmetries at the LHCb experiment are described. The algorithms have been developed using simulated events and optimized and calibrated with B+→J/ψK+, B0→J/ψK∗0 and B0→D∗-μ+νμ decay modes with 0.37 fb-1 of data collected in pp collisions at [Formula: see text] during the 2011 physics run. The opposite-side tagging power is determined in the B+→J/ψK+ channel to be (2.10±0.08±0.24) %, where the first uncertainty is statistical and the second is systematic.
Collapse
|
33
|
Measurement of ϒ production in pp collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2012; 72:2025. [PMID: 25814836 PMCID: PMC4370820 DOI: 10.1140/epjc/s10052-012-2025-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 04/20/2012] [Indexed: 05/28/2023]
Abstract
The production of ϒ(1S), ϒ(2S) and ϒ(3S) mesons in proton-proton collisions at the centre-of-mass energy of [Formula: see text] is studied with the LHCb detector. The analysis is based on a data sample of 25 pb-1 collected at the Large Hadron Collider. The ϒ mesons are reconstructed in the decay mode ϒ→μ+μ- and the signal yields are extracted from a fit to the μ+μ- invariant mass distributions. The differential production cross-sections times dimuon branching fractions are measured as a function of the ϒ transverse momentum pT and rapidity y, over the range pT <15 GeV/c and 2.0
Collapse
|
34
|
First evidence of direct CP violation in charmless two-body decays of Bs0 mesons. PHYSICAL REVIEW LETTERS 2012; 108:201601. [PMID: 23003138 DOI: 10.1103/physrevlett.108.201601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Indexed: 06/01/2023]
Abstract
Using a data sample corresponding to an integrated luminosity of 0.35 fb-1 collected by LHCb in 2011, we report the first evidence of CP violation in the decays of Bs0} mesons to K±π∓ pairs, ACP(Bs0→Kπ)=0.27±0.08(stat)±0.02(syst), with a significance of 3.3σ. Furthermore, we report the most precise measurement of CP violation in the decays of B0 mesons to K±π∓ pairs, ACP(B0→Kπ)=-0.088±0.011(stat)±0.008(syst), with a significance exceeding 6σ.
Collapse
|
35
|
Differential branching fraction and angular analysis of the decay B0 → K*0 μ+ μ-. PHYSICAL REVIEW LETTERS 2012; 108:181806. [PMID: 22681061 DOI: 10.1103/physrevlett.108.181806] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Indexed: 06/01/2023]
Abstract
The angular distributions and the partial branching fraction of the decay B0 → K*0 μ+ μ- are studied by using an integrated luminosity of 0.37 fb(-1) of data collected with the LHCb detector. The forward-backward asymmetry of the muons, A(FB), the fraction of longitudinal polarization, F(L), and the partial branching fraction dB/dq2 are determined as a function of the dimuon invariant mass. The measurements are in good agreement with the standard model predictions and are the most precise to date. In the dimuon invariant mass squared range 1.00-6.00 GeV2/c4, the results are A(FB)=-0.06(-0.14)(+0.13)±0.04, F(L)=0.55±0.10±0.03, and dB/dq2=(0.42±0.06±0.03)×10(-7) c4/GeV2. In each case, the first error is statistical and the second systematic.
Collapse
|
36
|
First observation of the decays B(0) → D(+)K(-)π(+)π(-) and B(-) → D(0)K(-)π(+)π(-). PHYSICAL REVIEW LETTERS 2012; 108:161801. [PMID: 22680708 DOI: 10.1103/physrevlett.108.161801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Indexed: 06/01/2023]
Abstract
First observations of the Cabibbo-suppressed decays B(0) → D(+)K(-)π(+)π(-) and B(-) → D(0)K(-)π(+)π(-) are reported using 35 pb(-1) of data collected with the LHCb detector. Their branching fractions are measured with respect to the corresponding Cabibbo-favored decays, from which we obtain B(B(0) → D(+)K(-)π(+)π(-))/B(B(0) → D(+)π(-)π(+)π(-))=(5.9±1.1±0.5)×10(-2) and B(B(-) → D(0)K(-)π(+)π(-))/B(B(-) → D(0)π(-)π(+)π(-))=(9.4±1.3±0.9)×10(-2), where the uncertainties are statistical and systematic, respectively. The B(-) → D(0)K(-)π(+)π(-) decay is particularly interesting, as it can be used in a similar way to B(-) → D(0)K(-) to measure the Cabibbo-Kobayashi-Maskawa phase γ.
Collapse
|
37
|
Observation of B(s)(0) → J/ψf(2)'(1525) in J/ψK+ K- final states. PHYSICAL REVIEW LETTERS 2012; 108:151801. [PMID: 22587241 DOI: 10.1103/physrevlett.108.151801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Indexed: 05/31/2023]
Abstract
The decay B(s)(0) → J/ψK+ K- is investigated using 0.16 fb(-1) of data collected with the LHCb detector using 7 TeV pp collisions. Although the J/ψϕ channel is well known, final states at higher K+ K- masses have not previously been studied. In the K+ K- mass spectrum we observe a significant signal in the f(2)'(1525) region as well as a nonresonant component. After subtracting the nonresonant component, we find B(B(s)(0) → J/ψf(2)'(1525))/B(B(s)(0) → J/ψϕ) = (26.4 ± 2.7 ± 2.4)%.
Collapse
|
38
|
Evidence for CP violation in time-integrated D0→h(-)h(+) decay rates. PHYSICAL REVIEW LETTERS 2012; 108:111602. [PMID: 22540460 DOI: 10.1103/physrevlett.108.111602] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Indexed: 05/31/2023]
Abstract
A search for time-integrated CP violation in D(0)→h(-)h(+) (h=K, π) decays is presented using 0.62 fb(-1) of data collected by LHCb in 2011. The flavor of the charm meson is determined by the charge of the slow pion in the D(*+)→D(0)π(+) and D(*-)→D[over ¯](0)π(-) decay chains. The difference in CP asymmetry between D(0)→K(-)K(+) and D(0)→π(-)π(+), ΔA(CP)≡A(CP)(K(-)K(+))-A(CP)(π(-)π(+)), is measured to be [-0.82±0.21(stat)±0.11(syst)]%. This differs from the hypothesis of CP conservation by 3.5 standard deviations.
Collapse
|
39
|
Search for lepton number violating decays B+ → π- μ+ μ+ and B+ → K- μ+ μ+. PHYSICAL REVIEW LETTERS 2012; 108:101601. [PMID: 22463398 DOI: 10.1103/physrevlett.108.101601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Indexed: 05/31/2023]
Abstract
A search is performed for the lepton number violating decay B+ → h- μ+ μ+, where h- represents a K- or a π-, using an integrated luminosity of 36 pb(-1) of data collected with the LHCb detector. The decay is forbidden in the standard model but allowed in models with a Majorana neutrino. No signal is observed in either channel and limits of B(B+ → K- μ+ μ+) < 5.4×10(-8) and B(B+ → π- μ+ μ+) < 5.8×10(-8) are set at the 95% confidence level. These improve the previous best limits by factors of 40 and 30, respectively.
Collapse
|
40
|
Measurement of the CP-violating phase ϕ(s) in the decay B(s)(0) → J/ψϕ. PHYSICAL REVIEW LETTERS 2012; 108:101803. [PMID: 22463401 DOI: 10.1103/physrevlett.108.101803] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Indexed: 05/31/2023]
Abstract
We present a measurement of the time-dependent CP-violating asymmetry in B(s)(0) → J/ψϕ decays, using data collected with the LHCb detector at the LHC. The decay time distribution of B(s)(0) → J/ψϕ is characterized by the decay widths Γ(H) and Γ(L) of the heavy and light mass eigenstates, respectively, of the B(s)(0) - B(s)(0) system and by a CP-violating phase ϕ(s). In a sample of about 8500 B(s)(0) → J/ψϕ events isolated from 0.37 fb(-1) of pp collisions at sqrt[s] = 7 TeV, we measure ϕ(s) = 0.15 ± 0.18(stat) ± 0.06(syst) rad. We also find an average B(s)(0) decay width Γ(s) ≡ (Γ(L) + Γ(H))/2 = 0.657 ± 0.009(stat) ± 0.008(syst) ps(-1) and a decay width difference ΔΓ(s) ≡ Γ(L) - Γ(H) = 0.123 ± 0.029(stat) ± 0.011(syst) ps(-1). Our measurement is insensitive to the transformation (ϕ(s),ΔΓ(s)) ↦ (π - ϕ(s), -ΔΓ(s)).
Collapse
|
41
|
Peptide mapping and disulfide bond analysis of myeloid progenitor inhibitory chemokine and keratinocyte growth factor by matrix-assisted laser desorption ionization mass spectrometry. Anal Biochem 1999; 267:125-34. [PMID: 9918664 DOI: 10.1006/abio.1998.3003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Peptide mapping and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) were conducted to characterize the human genome-based recombinant proteins. Accurate mass values for the deleted forms of the myeloid progenitor inhibitory factor chemokine (MPIF-1d23), and the keratinocyte growth factor (KGF-2d33) were measured as 8848.55 +/- 0.25 and 16,175.87 +/- 0.89 Da, respectively. The mass accuracy of delayed ion extraction MALDI-MS measurements was within 20 ppm of the cDNA predicted value. Reduction and alkylation of the chemokine showed the presence of six cysteine residues and three disulfide bonds. Additional confirmation of disulfide bonding among the cysteine residues of the chemokine was demonstrated by identifying the RP-HPLC separated tryptic and endoprotease Glu-C peptides. Three methionine residues of the chemokine were identified by MALDI-MS of its cyanogen bromide (CNBr) cleavage products. The KGF-2d33 growth factor, however, lacked the disulfide bonding between the two-cysteine residues and contained two free sulfhydryl groups. Direct analysis of the growth factor CNBr digest showed 7542.99, 4993.4, and 3107.7 Da peptides, which identified the methionine residues. Peptide mapping mass spectrometry indicated that host-specific posttranslational modifications had not influenced the gene expression work.
Collapse
|