418 research outputs found
Study of the ψ2(3823) and χc1(3872) states in B+ → (J/ψπ+π−)K+ decays
No full textThe decays B+→ J/ψπ+π−K+ are studied using a data set corresponding to an integrated luminosity of 9 fb−1 collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate ψ2(3823), χc1(3872) and ψ(2S) states are reported. The values areBB+→ψ2(3823)K+×Bψ2(3823)→J/ψπ+π−BB+→χc1(3872)K+×Bχc1(3872)→J/ψπ+π−=(3.56±0.67±0.11)×10−2,BB+→ψ2(3823)K+×Bψ2(3823)→J/ψπ+π−BB+→ψ(2S)K+×Bψ(2S)→J/ψπ+π−=(1.31±0.25±0.04)×10−3,BB+→χc1(3872)K+×Bχc1(3872)→J/ψπ+π−BB+→ψ(2S)K+×Bψ(2S)→J/ψπ+π−=(3.69±0.07±0.06)×10−2, where the first uncertainty is statistical and the second is systematic. The decay of B+→ ψ2(3823)K+ with ψ2(3823) → J/ψπ+π− is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the ψ2(3823), χc1(3872) and ψ(2S) states are measured to be mχc1(3872)−mψ2(3823)=47.50±0.53±0.13MeV/c2,mψ2(3823)−mψ2(2S)=137.98±0.53±0.14MeV/c2,mχc1(3872)−mψ2(2S)=185.49±0.06±0.03MeV/c2, resulting in the most precise determination of the χc1(3872) mass. The width of the ψ2(3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the χc1(3872) state is measured to be Γχc1(3872)BW=0.96−0.18+0.19±0.21MeV which is inconsistent with zero by 5.5 standard deviations. [Figure not available: see fulltext.
Study of the ψ 2 (3823) and χ c1 (3872) states in B + → (J /ψπ + π − )K + decays
No full textAbstract: The decays B+→ J/ψπ+π−K+ are studied using a data set corresponding to an integrated luminosity of 9 fb−1 collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate ψ2(3823), χc1(3872) and ψ(2S) states are reported. The values areBB+→ψ23823K+×Bψ23823→J/ψπ+π−BB+→χc13872K+×Bχc13872→J/ψπ+π−=3.56±0.67±0.11×10−2, BB+→ψ23823K+×Bψ23823→J/ψπ+π−BB+→ψ2SK+×Bψ2S→J/ψπ+π−=1.31±0.25±0.04×10−3, BB+→χc13872K+×Bχc13872→J/ψπ+π−BB+→ψ2SK+×Bψ2S→J/ψπ+π−=3.69±0.07±0.06×10−2, where the first uncertainty is statistical and the second is systematic. The decay of B+→ ψ2(3823)K+ with ψ2(3823) → J/ψπ+π− is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the ψ2(3823), χc1(3872) and ψ(2S) states are measured to be mχc13872−mψ23823=47.50±0.53±0.13MeV/c2, mψ23823−mψ22S=137.98±0.53±0.14MeV/c2, mχc13872−mψ22S=185.49±0.06±0.03MeV/c2, resulting in the most precise determination of the χc1(3872) mass. The width of the ψ2(3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the χc1(3872) state is measured to be Γχc13872BW=0.96−0.18+0.19±0.21MeV which is inconsistent with zero by 5.5 standard deviations
Study of B-+/-,B-0 -> J/psi(K+K-K +/-,0) and search for B-0 -> J/psi phi at BABAR
No full textWe study the rare B meson decays B±,0→J/ψK+K-K±,0, B±,0→J/ψφK±,0, and search for B0→J/ψφ, using 469×106 BB ̄ events collected at the γ(4S) resonance with the BABAR detector at the PEP-II e+e- asymmetric energy collider. We present new measurements of branching fractions and a study of the J/ψφ mass distribution in search of new charmonium-like states. In addition, we search for the decay B0→J/ψφ and find no evidence of a signal
Search for a CP-odd Higgs boson decaying to Zh in pp collisions at root s=8 TeV with the ATLAS detector
No full textSee paper for full list of authors – 13 pages plus author list + cover pages (30 pages total), 5 figures, 2 tables, submitted to Phys. Lett. B, All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2013-06/International audienceA search for a heavy, CP-odd Higgs boson, , decaying into a boson and a 125 GeV Higgs boson, , with the ATLAS detector at the LHC is presented. The search uses proton--proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb. Decays of CP-even bosons to or pairs with the boson decaying to electron or muon pairs are considered, as well as decays with the boson decaying to neutrinos. No evidence for the production of an boson in these channels is found and the 95% confidence level upper limits derived for \sigma (gg\rightarrow A) \times \mbox{BR}(A \rightarrow Zh) \times \mbox{BR}(h \rightarrow f\bar{f}) are 0.098--0.013 pb for and 0.57--0.014 pb for in a range of 220--1000 GeV. The results are combined and interpreted in the context of two-Higgs doublet models
Search for pair production of Higgs bosons in the bb¯ bb¯ final state using proton-proton collisions at √s=13 TeV with the ATLAS detector
No full textA search for Higgs boson pair production in the bb¯ bb¯ final state is carried out with up to 36.1 fb−1 of LHC proton-proton collision data collected at s=13 TeV with the ATLAS detector in 2015 and 2016. Three benchmark signals are studied: a spin-2 graviton decaying into a Higgs boson pair, a scalar resonance decaying into a Higgs boson pair, and Standard Model non-resonant Higgs boson pair production. Two analyses are carried out, each implementing a particular technique for the event reconstruction that targets Higgs bosons reconstructed as pairs of jets or single boosted jets. The resonance mass range covered is 260–3000 GeV. The analyses are statistically combined and upper limits on the production cross section of Higgs boson pairs times branching ratio to bb¯ bb¯ are set in each model. No significant excess is observed; the largest deviation of data over prediction is found at a mass of 280 GeV, corresponding to 2.3 standard deviations globally. The observed 95% confidence level upper limit on the non-resonant production is 13 times the Standard Model prediction.[Figure not available: see fulltext.]
Search for the Standard Model Higgs boson produced in association with top quarks and decaying into bb¯ in pp collisions at √s=8TeV with the ATLAS detector
No full textA search for the Standard Model Higgs boson produced in association with a top-quark pair, tt¯H, is presented. The analysis uses 20.3 fb−1 of pp collision data at s√=8TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the H→bb¯ decay mode and uses events containing one or two electrons or muons. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A neural network is used to discriminate between signal and background events, the latter being dominated by tt¯+jets production. In the single-lepton channel, variables calculated using a matrix element method are included as inputs to the neural network to improve discrimination of the irreducible tt¯+bb¯ background. No significant excess of events above the background expectation is found and an observed (expected) limit of 3.4 (2.2) times the Standard Model cross section is obtained at 95 % confidence level. The ratio of the measured tt¯H signal cross section to the Standard Model expectation is found to be μ=1.5±1.1 assuming a Higgs boson mass of 125GeV
Search for exotic decays of the Higgs boson to a pair of pseudoscalars in the \u3bc\u3bc bb and \u3c4\u3c4 bb final states
No full textAbstract: A search for exotic decays of the Higgs boson (H) with a mass of 125 GeV to a pair of light pseudoscalars a(1) is performed in final states where one pseudoscalar decays to two b quarks and the other to a pair of muons or tau leptons. A data sample of proton-proton collisions at root s = 13 TeV corresponding to an integrated luminosity of 138 fb(-1) recorded with the CMS detector is analyzed. No statistically significant excess is observed over the standard model backgrounds. Upper limits are set at 95% confidence level (CL) on the Higgs boson branching fraction to mu mu bb and to tau tau bb, via a pair of a(1)s. The limits depend on the pseudoscalar mass m(a1) and are observed to be in the range (0.17-3.3) x10(-4) and (1.7-7.7) x10(-2) in the mu mu bb and tau tau bb final states, respectively. In the framework of models with two Higgs doublets and a complex scalar singlet (2HDM+S), the results of the two final states are combined to determine upper limits on the branching fraction B(H -> a(1)a(1) -> llbb) at 95% CL, with l being a muon or a tau lepton. For different types of 2HDM+S, upper bounds on the branching fraction B(H -> a(1)a(1)) are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space, B(H -> a(1)a(1)) values above 0.23 are excluded at 95% CL for m(a1) values between 15 and 60 GeV
Measurement of sigma (pp -> bbX) at √s=7 TeV in the forward region
No full textDecays of b hadrons into final states containing a D-0 meson and a muon are used to measure the bb; production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. In the pseudorapidity interval 2 < eta < 6 and integrated over all transverse momenta we find that the average cross-section to produce b-flavoured or b-flavoured hadrons is (75.3 +/- 5.4 +/- 13.0) mu b
Combined search for anomalous pseudoscalar HVV couplings in VH(H→bb‾) production and H → VV decay
No full textA search for anomalous pseudoscalar couplings of the Higgs boson H to electroweak vector bosons V (=W or Z) in a sample of proton–proton collision events corresponding to an integrated luminosity of 18.9 fb−1 at a center-of-mass energy of 8 TeV is presented. Events consistent with the topology of associated VH production, where the Higgs boson decays to a pair of bottom quarks and the vector boson decays leptonically, are analyzed. The consistency of data with a potential pseudoscalar contribution to the HVV interaction, expressed by the effective pseudoscalar cross section fractions fa3, is assessed by means of profile likelihood scans. Results are given for the VH channels alone and for a combined analysis of the VH and previously published H→VV channels. Under certain assumptions, fa3ZZ>0.0034 is excluded at 95% confidence level in the combination. Scenarios in which these assumptions are relaxed are also considered
Search for higgsino pair production in pp collisions at sqrt(s) = 13 TeV in final states with large missing transverse momentum and two Higgs bosons decaying via H to bb-bar
No full textResults are reported from a search for new physics in 13 TeV proton-proton collisions in the final state with large missing transverse momentum and two Higgs bosons decaying via H→bb¯. The search uses a data sample accumulated by the CMS experiment at the LHC in 2016, corresponding to an integrated luminosity of 35.9 fb-1. The search is motivated by models based on gauge-mediated supersymmetry breaking, which predict the electroweak production of a pair of Higgsinos, each of which can decay via a cascade process to a Higgs boson and an undetected lightest supersymmetric particle. The observed event yields in the signal regions are consistent with the standard model background expectation obtained from control regions in data. Higgsinos in the mass range 230–770 GeV are excluded at 95% confidence level in the context of a simplified model for the production and decay of approximately degenerate Higgsinos.Results are reported from a search for new physics in 13 TeV proton-proton collisions in the final state with large missing transverse momentum and two Higgs bosons decaying via H to bb-bar. The search uses a data sample accumulated by the CMS experiment at the LHC in 2016, corresponding to an integrated luminosity of 35.9 inverse femtobarns. The search is motivated by models based on gauge-mediated supersymmetry breaking, which predict the electroweak production of a pair of higgsinos, each of which can decay via a cascade process to a Higgs boson and an undetected lightest supersymmetric particle. The observed event yields in the signal regions are consistent with the standard model background expectation obtained from control regions in data. Higgsinos in the mass range 230-770 GeV are excluded at 95% confidence level in the context of a simplified model for the production and decay of approximately degenerate higgsinos
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