Publications
725 results found
Alenkov V, Buzanov O, Dosovitskiy G, et al., 2019, Irradiation studies of a multi-doped Gd3Al2Ga3O12 scintillator, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Vol: 916, Pages: 226-229, ISSN: 0168-9002
Sun J, Bediaga I, Cruz Torres M, et al., 2019, Prompt Lambda(+)(c) baryons and D-0 meson production cross-section and nuclear modification in pPb collisions at root S-NN=5.02 TeV with the LHCb detector, 27th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter), Publisher: ELSEVIER SCIENCE BV, Pages: 683-686, ISSN: 0375-9474
Bursche A, Bediaga I, Cruz Torres M, et al., 2019, Study of coherent J/psi production in lead-lead collisions at root s(NN)=5 TeV with the LHCb experiment, 27th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter), Publisher: Elsevier, Pages: 247-250, ISSN: 0375-9474
Coherent production of J/ψ mesons is studied in lead-lead collision data at a nucleon-nucleon centre-of-mass energy of 5 TeV collected by the LHCb experiment. The data set corresponds to an integrated luminosity of about 10μb−1. The J/ψ mesons are reconstructed in the dimuon final state, where the muons are detected within the pseudorapidity region 2.0 < η < 4.5. The J/ψ mesons are required to have transverse momentum pT < 1 GeV and rapidity 2.0 < y < 4.5. The cross-section within this fiducial region is measured to be σ = 5.3 ± 0.2 (stat) ± 0.5 (syst) ± 0.7 (lumi) mb. The differential cross-section is also measured in five bins of J/ψ rapidity. The results are compared to predictions from phenomenological models.
Aaij R, Abellán Beteta C, Adeva B, et al., 2019, Observation of Two Resonances in the Λ_{b}^{0}π^{±} Systems and Precise Measurement of Σ_{b}^{±} and Σ_{b}^{*±} Properties., Phys Rev Lett, Vol: 122, Pages: 012001-012001, ISSN: 0031-9007
The first observation of two structures consistent with resonances in the final states Λ_{b}^{0}π^{-} and Λ_{b}^{0}π^{+} is reported using samples of pp collision data collected by the LHCb experiment at sqrt[s]=7 and 8 TeV, corresponding to an integrated luminosity of 3 fb^{-1}. The ground states Σ_{b}^{±} and Σ_{b}^{*±} are also confirmed and their masses and widths are precisely measured.
Aaij R, Beteta CA, Adeva B, et al., 2019, Measurement of the Charm-Mixing Parameter y(CP), Physical Review Letters, Vol: 122, ISSN: 0031-9007
A measurement of the charm-mixing parameter yCP using D0→K+K−, D0→π+π−, and D0→K−π+ decays is reported. The D0 mesons are required to originate from semimuonic decays of B− and ¯¯¯B0 mesons. These decays are partially reconstructed in a data set of proton-proton collisions at center-of-mass energies of 7 and 8 TeV collected with the LHCb experiment and corresponding to an integrated luminosity of 3 fb−1. The yCP parameter is measured to be (0.57±0.13(stat)±0.09(syst))%, in agreement with, and as precise as, the current world-average value.
Aaij R, Beteta CA, Adeva B, et al., 2018, Search for lepton-flavour-violating decays of Higgs-like bosons, European Physical Journal C: Particles and Fields, Vol: 78, ISSN: 1434-6044
A search is presented for a Higgs-like boson with mass in the range 45 to 195GeV/c2 decaying into a muon and a tau lepton. The dataset consists of proton-proton interactions at a centre-of-mass energy of 8 TeV, collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb −1. The tau leptons are reconstructed in both leptonic and hadronic decay channels. An upper limit on the production cross-section multiplied by the branching fraction at 95% confidence level is set and ranges from 22pb for a boson mass of 45GeV/c2 to 4pb for a mass of 195GeV/c2.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Search for CP violation in Lambda(0)(b)-> pK(- )and Lambda(0)(b) -> p pi(-) decays, Physics Letters B, Vol: 787, Pages: 124-133, ISSN: 0370-2693
A search for CP violation in 0b→pK−andΛ0b→pπ− decays is presented using a sample of pp collisions collected with the LHCb detector and corresponding to an integrated luminosity of 3.0. The CP -violating asymmetries are measured to be ApK−CP=−0.020±0.013±0.019 and Apπ−CP=−0.035±0.017±0.020 and their difference ApK−CP−Apπ−CP=0.014±0.022±0.010, where the first uncertainties are statistical and the second systematic. These are the most precise measurements of such asymmetries to date.
Aaij R, Beteta CA, Adeva B, et al., 2018, Evidence for an nc(1S)ff- resonance in B0 yc(1S)K+ decays, EUROPEAN PHYSICAL JOURNAL C, Vol: 78, ISSN: 1434-6044
Aaij R, Abelian Beteta C, Adeva B, et al., 2018, Measurement of antiproton production in p-He collisions at root S-NN=110 GeV, Physical Review Letters, Vol: 121, ISSN: 0031-9007
The cross section for prompt antiproton production in collisions of protons with an energy of 6.5 TeV incident on helium nuclei at rest is measured with the LHCb experiment from a data set corresponding to an integrated luminosity of 0.5 nb−1. The target is provided by injecting helium gas into the LHC beam line at the LHCb interaction point. The reported results, covering antiproton momenta between 12 and 110 GeV/c, represent the first direct determination of the antiproton production cross section in p−He collisions, and impact the interpretation of recent results on antiproton cosmic rays from space-borne experiments.
Aaij R, Beteta CA, Adeva B, et al., 2018, Study of Gamma production in pPb collisions at root(s)(NN) (=)8.16 TeV, Journal of High Energy Physics, Vol: 2018, ISSN: 1029-8479
The production of ϒ(nS) mesons (n = 1, 2, 3) in pPb and Pbp collisions at a centre-of-mass energy per nucleon pair sNN−−−√=8.16 TeV is measured by the LHCb experiment, using a data sample corresponding to an integrated luminosity of 31.8 nb−1. The ϒ(nS) mesons are reconstructed through their decays into two opposite-sign muons. The measurements comprise the differential production cross-sections of the ϒ(1S) and ϒ(2S) states, their forward-to-backward ratios and nuclear modification factors. The measurements are performed as a function of the transverse momentum pT and rapidity in the nucleon-nucleon centre-of-mass frame y* of the ϒ(nS) states, in the kinematic range pT < 25 GeV/c and 1.5 < y* < 4.0 (−5.0 < y* < −2.5) for pPb (Pbp) collisions. In addition, production cross-sections for ϒ(3S) are measured integrated over phase space and the production ratios between all three ϒ(nS) states are determined. Suppression for bottomonium in proton-lead collisions is observed, which is particularly visible in the ratios. The results are compared to theoretical models.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Measurement of the time-integrated <i>CP</i> asymmetry in <i>D</i> <SUP>0</SUP> → <i>K</i> <i><sub>S</sub></i> <SUP>0</SUP> <i>K</i> <i><sub>S</sub></i> <SUP>0</SUP> decays, Publisher: SPRINGER
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- Citations: 6
Aaij R, Adeva B, Adinolfi M, et al., 2018, Observation of the decay B-s(0) -> (D)over-bar(0)K (+) K-, Physical Review D - Particles, Fields, Gravitation and Cosmology, Vol: 98, ISSN: 1550-2368
The first observation of the B0s→¯D0K+K− decay is reported, together with the most precise branching fraction measurement of the mode B0→¯D0K+K−. The results are obtained from an analysis of pp collision data corresponding to an integrated luminosity of 3.0 fb−1. The data were collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. The branching fraction of the B0→¯D0K+K− decay is measured relative to that of the decay B0→¯D0π+π− to be B(B0→¯D0K+K−)B(B0→¯D0π+π−)=(6.9±0.4±0.3)%, where the first uncertainty is statistical and the second is systematic. The measured branching fraction of the B0s→¯D0K+K− decay mode relative to that of the corresponding B0 decay is B(B0s→¯D0K+K−)B(B0→¯D0K+K−)=(93.0±8.9±6.9)%. Using the known branching fraction of B0→¯D0π+π−, the values of B(B0→¯D0K+K−)=(6.1±0.4±0.3±0.3)×10−5 and B(B0s→¯D0K+K−)=(5.7±0.5±0.4±0.5)×10−5 are obtained, where the third uncertainties arise from the branching fraction of the decay modes B0→¯D0π+π− and B0→¯D0K+K−, respectively.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Observation of B-s(0) -> (D)over-bar*(0)phi and search for B-0 -> (D)over-bar(0)phi decays, PHYSICAL REVIEW D, Vol: 98, ISSN: 2470-0010
The first observation of the B0s→¯D*0ϕ decay is reported, with a significance of more than seven standard deviations, from an analysis of pp collision data corresponding to an integrated luminosity of 3 fb−1, collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. The branching fraction is measured relative to that of the topologically similar decay B0→¯D0π+π− and is found to be B(B0s→¯D*0ϕ)=(3.7±0.5±0.3±0.2)×10−5, where the first uncertainty is statistical, the second systematic, and the third from the branching fraction of the B0→¯D0π+π− decay. The fraction of longitudinal polarization in this decay is measured to be fL=(73±15±4)%. The most precise determination of the branching fraction for the B0s→¯D0ϕ decay is also obtained, B(B0s→¯D0ϕ)=(3.0±0.3±0.2±0.2)×10−5. An upper limit, B(B0→¯D0ϕ)<2.0 (2.3)×10−6 at 90% (95%) confidence level is set. A constraint on the ω−ϕ mixing angle δ is set at |δ|<5.2° (5.5°) at 90% (95%) confidence level.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Central exclusive production of J/psi and (2S) mesons in pp collisions at p s=13 TeV, JOURNAL OF HIGH ENERGY PHYSICS, Vol: 2018, ISSN: 1029-8479
Measurements are reported of the central exclusive production of J/ψ and ψ(2S) mesons in pp collisions at a centre-of-mass energy of 13 TeV. Backgrounds are significantly reduced compared to previous measurements made at lower energies through the use of new forward shower counters. The products of the cross-sections and the branching fractions for the decays to dimuons, where both muons are within the pseudorapidity range 2.0 < η < 4.5, are measured to beσJ/ψ→μ+μ−=435±18±11±17 pbσψ(2S)→μ+μ−=11.1±1.1±0.3±0.4 pb.The first uncertainties are statistical, the second are systematic, and the third are due to the luminosity determination. The cross-sections are also measured differentially for meson rapidities between 2.0 and 4.5. Good agreement is observed with theoretical predictions. Photoproduction cross-sections are derived and compared to previous experiments, and a deviation from a pure power-law extrapolation of lower energy data is observed.
Aaij R, Adeva B, Adinolfi M, et al., 2018, First Observation of the Doubly Charmed Baryon Decay Ξ_{cc}^{++}→Ξ_{c}^{+}π^{+}.
The doubly charmed baryon decay Ξ_{cc}^{++}→Ξ_{c}^{+}π^{+} is observed for the first time, with a statistical significance of 5.9σ, confirming a recent observation of the baryon in the Λ_{c}^{+}K^{-}π^{+}π^{+} final state. The data sample used corresponds to an integrated luminosity of 1.7 fb^{-1}, collected by the LHCb experiment in pp collisions at a center-of-mass energy of 13 TeV. The Ξ_{cc}^{++} mass is measured to be 3620.6±1.5(stat)±0.4(syst)±0.3(Ξ_{c}^{+}) MeV/c^{2} and is consistent with the previous result. The ratio of branching fractions between the decay modes is measured to be [B(Ξ_{cc}^{++}→Ξ_{c}^{+}π^{+})×B(Ξ_{c}^{+}→pK^{-}π^{+})]/[B(Ξ_{cc}^{++}→Λ_{c}^{+}K^{-}π^{+}π^{+})×B(Λ_{c}^{+}→pK^{-}π^{+})]=0.035±0.009(stat)±0.003(syst).
Aaij R, Adeva B, Adinolfi M, et al., 2018, First observation of the doubly charmed baryon decay Xi(++)(cc) -> Xi(+)(c)pi(+), Physical Review Letters, Vol: 121, ISSN: 0031-9007
The doubly charmed baryon decay Ξ++cc→Ξ+cπ+ is observed for the first time, with a statistical significance of 5.9σ, confirming a recent observation of the baryon in the Λ+cK−π+π+ final state. The data sample used corresponds to an integrated luminosity of 1.7 fb−1, collected by the LHCb experiment in pp collisions at a center-of-mass energy of 13 TeV. The Ξ++cc mass is measured to be 3620.6±1.5(stat)±0.4(syst)±0.3(Ξ+c) MeV/c2 and is consistent with the previous result. The ratio of branching fractions between the decay modes is measured to be [B(Ξ++cc→Ξ+cπ+)×B(Ξ+c→pK−π+)]/[B(Ξ++cc→Λ+cK−π+π+)×B(Λ+c→pK−π+)]=0.035±0.009(stat)±0.003(syst)
Aaij R, Adeva B, Adinolfi M, et al., 2018, Measurement of the CKM angle using B-+/- DK +/- with D -> KS0(+-),(KsK+K-)-K-0 decays (vol 08, 176, 2018), JOURNAL OF HIGH ENERGY PHYSICS, Vol: 2018, ISSN: 1029-8479
Aaij R, Adeva B, Adinolfi M, et al., 2018, Search for beautiful tetraquarks in the ?(1S)(+-) invariant-mass spectrum, Journal of High Energy Physics, Vol: 10, Pages: 1-22, ISSN: 1029-8479
The ϒ(1S)μ+μ− invariant-mass distribution is investigated for a possible exotic meson state composed of two b quarks and two b¯¯ quarks, Xbb¯bb¯. The analysis is based on a data sample of pp collisions recorded with the LHCb detector at centre-of-mass energies s√=7, 8 and 13 TeV, corresponding to an integrated luminosity of 6.3 fb−1. No significant excess is found, and upper limits are set on the product of the production cross-section and the branching fraction as functions of the mass of the Xbb¯bb¯ state. The limits are set in the fiducial volume where all muons have pseudorapidity in the range [2.0, 5.0], and the Xbb¯bb¯ state has rapidity in the range [2.0, 4.5] and transverse momentum less than 15 GeV/c.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Measurement of Z -> tau(+)tau(-) production in proton-proton collisions at root s=8 TeV, Journal of High Energy Physics, Vol: 2018, ISSN: 1029-8479
A measurement of Z → τ +τ − production cross-section is presented using data, corresponding to an integrated luminosity of 2 fb−1, from pp collisions at s√=8 TeV collected by the LHCb experiment. The τ +τ − candidates are reconstructed in final states with the first tau lepton decaying leptonically, and the second decaying either leptonically or to one or three charged hadrons. The production cross-section is measured for Z bosons with invariant mass between 60 and 120 GeV/c2, which decay to tau leptons with transverse momenta greater than 20 GeV/c and pseudorapidities between 2.0 and 4.5. The cross-section is determined to be σpp→Z→τ+τ−=95.8±2.1±4.6±0.2±1.1 pb, where the first uncertainty is statistical, the second is systematic, the third is due to the LHC beam energy uncertainty, and the fourth to the integrated luminosity uncertainty. This result is compatible with NNLO Standard model predictions. The ratio of the cross-sections for Z → τ+τ− to Z → μ+μ− (Z → e+e−), determined to be 1.01 ± 0.05 (1.02 ± 0.06), is consistent with the lepton-universality hypothesis in Z decays.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Angular moments of the decay Lambda(0)(b) -> Lambda mu(+)mu(-) at low hadronic recoil, Journal of High Energy Physics, Vol: 2018, ISSN: 1029-8479
An analysis of the angular distribution of the decay Λ b 0 → Λμ+μ− is presented, using data collected with the LHCb detector between 2011 and 2016 and corresponding to an integrated luminosity of approximately 5 fb−1. Angular observables are determined using a moment analysis of the angular distribution at low hadronic recoil, corresponding to the dimuon invariant mass squared range 15 < q2 < 20 GeV2/c4. The full basis of observables is measured for the first time. The lepton-side, hadron-side and combined forward-backward asymmetries of the decay are determined to beℓFB=−0.39±0.04(stat)±0.01(syst),AhFB=−0.30±0.05(stat)±0.02(syst),AℓhFB=+0.25±0.04(stat)±0.01(syst).The measurements are consistent with Standard Model predictions.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Erratum to: Differential branching fraction and angular analysis of Lambda(0)(b) -> Lambda mu(+)mu(-) decays, Journal of High Energy Physics, Vol: 2018, ISSN: 1029-8479
Aaij R, Adeva B, Adinolfi M, et al., 2018, Search for a dimuon resonance in the Upsilon mass region, Journal of High Energy Physics, Vol: 2018, ISSN: 1029-8479
A search is performed for a spin-0 boson, ϕ, produced in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, using prompt ϕ → μ+μ− decays and a data sample corresponding to an integrated luminosity of approximately 3.0 fb−1 collected with the LHCb detector. No evidence is found for a signal in the mass range from 5.5 to 15 GeV. Upper limits are placed on the product of the production cross-section and the branching fraction into the dimuon final state. The limits are comparable to the best existing over most of the mass region considered and are the first to be set near the ϒ resonances.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Observation of the decay Λ<inf>b</inf><sup>0</sup>→Λ<inf>c</inf><sup>+</sup>pp‾π<sup>−</sup>, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 784, Pages: 101-111, ISSN: 0370-2693
The decay Λb0→Λc+pp‾π−is observed using pp collision data collected with the LHCb detector at centre-of-mass energies of s=7 and 8 Tev, corresponding to an integrated luminosity of 3 fb−1. The ratio of branching fractions between Λb0→Λc+pp‾π−and Λb0→Λc+π−decays is measured to be [Formula presented]=0.0540±0.0023±0.0032. Two resonant structures are observed in the Λc+π−mass spectrum of the Λb0→Λc+pp‾π−decays, corresponding to the Σc(2455)0and Σc⁎(2520)0states. The ratios of branching fractions with respect to the decay Λb0→Λc+pp‾π−are [Formula presented]=0.089±0.015±0.006,[Formula presented]=0.119±0.020±0.014. In all of the above results, the first uncertainty is statistical and the second is systematic. The phase space is also examined for the presence of dibaryon resonances. No evidence for such resonances is found.
Aaij R, Collaboration L, Adeva B, et al., 2018, Measurement of the omega(0)(c) baryon lifetime, Physical Review Letters, Vol: 121, ISSN: 0031-9007
We report a measurement of the lifetime of the Ω0c baryon using proton-proton collision data at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3.0 fb−1 collected by the LHCb experiment. The sample consists of about 1000 Ω−b→Ω0cμ−¯νμX signal decays, where the Ω0c baryon is detected in the pK−K−π+ final state and X represents possible additional undetected particles in the decay. The Ω0c lifetime is measured to be τΩ0c=268±24±10±2 fs, where the uncertainties are statistical, systematic, and from the uncertainty in the D+ lifetime, respectively. This value is nearly four times larger than, and inconsistent with, the current world-average value.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Measurement of angular and CP asymmetries in D-0 -> pi(+) pi(-) mu(+) mu(-) and D-0 -> K+ K- mu(+) mu(-) decays, Physical Review Letters, Vol: 121, ISSN: 0031-9007
The first measurements of the forward-backward asymmetry of the dimuon pair (AFB), the triple-product asymmetry (A2ϕ), and the charge-parity-conjugation asymmetry (ACP), in D0→π+π−μ+μ− and D0→K+K−μ+μ− decays are reported. They are performed using data from proton-proton collisions collected with the LHCb experiment from 2011 to 2016, corresponding to a total integrated luminosity of 5 fb−1. The asymmetries are measured to be AFB(D0→π+π−μ+μ−)=(3.3±3.7±0.6)%, A2ϕ(D0→π+π−μ+μ−)=(−0.6±3.7±0.6)%, ACP(D0→π+π−μ+μ−)=(4.9±3.8±0.7)%, AFB(D0→K+K−μ+μ−)=(0±11±2)%, A2ϕ(D0→K+K−μ+μ−)=(9±11±1)%, ACP(D0→K+K−μ+μ−)=(0±11±2)%, where the first uncertainty is statistical and the second systematic. The asymmetries are also measured as a function of the dimuon invariant mass. The results are consistent with the standard model predictions.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Measurement of angular and CP asymmetries in D^{0}→π^{+}π^{-}μ^{+}μ^{-} and D^{0}→K^{+}K^{-}μ^{+}μ^{-} decays, Physical Review Letters, Vol: 121, ISSN: 0031-9007
The first measurements of the forward-backward asymmetry of the dimuon pair (A_{FB}), the triple-product asymmetry (A_{2ϕ}), and the charge-parity-conjugation asymmetry (A_{CP}), in D^{0}→π^{+}π^{-}μ^{+}μ^{-} and D^{0}→K^{+}K^{-}μ^{+}μ^{-} decays are reported. They are performed using data from proton-proton collisions collected with the LHCb experiment from 2011 to 2016, corresponding to a total integrated luminosity of 5 fb^{-1}. The asymmetries are measured to be A_{FB}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(3.3±3.7±0.6)%, A_{2ϕ}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(-0.6±3.7±0.6)%, A_{CP}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(4.9±3.8±0.7)%, A_{FB}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(0±11±2)%, A_{2ϕ}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(9±11±1)%, A_{CP}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(0±11±2)%, where the first uncertainty is statistical and the second systematic. The asymmetries are also measured as a function of the dimuon invariant mass. The results are consistent with the standard model predictions.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Observation of the decay (B)over-bar(s)(0) -> chi(c2) K+K- in the phi mass region, Journal of High Energy Physics, Vol: 2018, ISSN: 1029-8479
The B¯¯¯¯0s→χc2K+K−decay mode is observed and its branching fraction relative to the corresponding χc1 decay mode, in a ±15 MeV/c2 window around the ϕ mass, is found to beB(B¯¯¯¯0s→χc2K+K−)B(B¯¯¯¯0s→χc1K+K−)=(17.1±3.1±0.4±0.9)%,where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the branching fractions of radiative χc decays. The decay mode B¯¯¯¯0s→χc1K+K−allows the B s 0 mass to be measured asm(B0s)=5366.83±0.25±0.27 MeV/c2,where the first uncertainty is statistical and the second systematic. A combination of this result with other LHCb determinations of the B s 0 mass is made.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Measurement of the CKM angle gamma using B-+/- -> DK +/- with D -> K-S(0)pi(+)pi(-), (KSK+K-)-K-0 decays, Journal of High Energy Physics, Vol: 2018, ISSN: 1029-8479
A binned Dalitz plot analysis of B± → DK± decays, with D → K S 0 π+π− and D → K S 0 K+K−, is used to perform a measurement of the CP-violating observables x± and y±, which are sensitive to the Cabibbo-Kobayashi-Maskawa angle γ. The analysis is performed without assuming any D decay model, through the use of information on the strong-phase variation over the Dalitz plot from the CLEO collaboration. Using a sample of proton-proton collision data collected with the LHCb experiment in 2015 and 2016, and corresponding to an integrated luminosity of 2.0 fb−1, the values of the CP violation parameters are found to be x− = (9.0 ± 1.7 ± 0.7 ± 0.4) × 10−2, y− = (2.1 ± 2.2 ± 0.5 ± 1.1) × 10−2, x+ = (−7.7 ± 1.9 ± 0.7 ± 0.4) × 10−2, and y+ = (−1.0 ± 1.9 ± 0.4 ± 0.9) × 10−2. The first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty (on the strong-phase measurements. These values are used to obtain γ = (87 − 12 + 11 )∘, rB = 0.086 − 0.014 + 0.013 , and δB = (101±11)°, where rB is the ratio between the suppressed and favoured B-decay amplitudes and δB is the corresponding strong-interaction phase difference. This measurement is combined with the result obtained using 2011 and 2012 data collected with the LHCb experiment, to give γ = (80 − 9 + 10 )∘, rB = 0.080 ± 0.011, and δB = (110 ± 10)°.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Observation of the decay Lambda(0)(b) -> psi(2S)p pi(-), Journal of High Energy Physics, Vol: 2018, ISSN: 1029-8479
The Cabibbo-suppressed decay Λ b 0 → ψ(2S)pπ− is observed for the first time using a data sample collected by the LHCb experiment in proton-proton collisions corresponding to 1.0, 2.0 and 1.9 fb−1 of integrated luminosity at centre-of-mass energies of 7, 8 and 13 TeV, respectively. The ψ(2S) mesons are reconstructed in the μ+μ− final state. The branching fraction with respect to that of the Λ b 0 → ψ(2S)pK− decay mode is measured to beB(Λ0b→ψ(2S)pπ−)B(Λ0b→ψ(2S)pK−)=(11.4±1.3±0.2)%,where the first uncertainty is statistical and the second is systematic. The ψ(2S)p and ψ(2S)π− mass spectra are investigated and no evidence for exotic resonances is found.
Aaij R, Adeva B, Adinolfi M, et al., 2018, Observation of a new Xi(-)(b) resonance, Physical Review Letters, Vol: 121, ISSN: 0031-9007
From samples of pp collision data collected by the LHCb experiment at √s=7, 8 and 13 TeV, corresponding to integrated luminosities of 1.0, 2.0 and 1.5 fb−1, respectively, a peak in both the Λ0bK− and Ξ0bπ− invariant mass spectra is observed. In the quark model, radially and orbitally excited Ξ−b resonances with quark content bds are expected. Referring to this peak as Ξb(6227)−, the mass and natural width are measured to be mΞb(6227)−=6226.9±2.0±0.3±0.2 MeV/c2 and ΓΞb(6227)−=18.1±5.4±1.8 MeV/c2, where the first uncertainty is statistical, the second is systematic, and the third, on mΞb(6227)−, is due to the knowledge of the Λ0b baryon mass. Relative production rates of the Ξb(6227)−→Λ0bK− and Ξb(6227)−→Ξ0bπ− decays are also reported.
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