1,433 research outputs found

    Measurements of the CKM angle phi_3/gamma

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    We present a review on the measurements of the CKM angle gamma (phi_3) as performed by the BABAR and Belle experiments at the asymmetric-energy e+e- B factories colliders PEP-II and KEKB.Comment: 11 pages, 10 figures, proceedings of the 5th Flavor Physics And CP Violation Conference (FPCP 2007

    CKM fits as of winter 2009 and sensitivity to New Physics

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    We present the status of the CKM matrix parameters in the framework of the Standard Model. We perform a model independent analysis to set constraints on additional effective parameters accounting for possible New Physics effects and to evaluate the present allowed space for these effects both from BdB_d and BsB_s mesons.Comment: proceedings for the Moriond 2009 EW sessio

    Resonant metamaterial absorbers for infrared spectral filtering: quasimodal analysis, design, fabrication and characterization

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    We present a modal analysis of metal-insulator-metal (MIM) based metamaterials in the far infrared region. These structures can be used as resonant reflection bandcut spectral filters that are independent of the polarization and direction of incidence because of the excitation of quasimodes (modes associated with a complex frequency) leading to quasi-total absorption. We fabricated large area samples made of chromium nanorod gratings on top of Si/Cr layers deposited on silicon substrate and measurements by Fourier Transform spectrophotometry show good agreement with finite element simulations. A quasimodal expansion method is developed to obtain a reduced order model that fits very well full wave simulations and that highlights excitation conditions of the modes.Comment: 8 pages, 7 figure

    Search for rare or forbidden decays of the D0 meson

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    We present a search for nine lepton-number-violating and three lepton-flavor-violating neutral charm decays of the type D0→h'−h−ℓ'+ℓ+ and D0→h'−h+ℓ'±ℓ∓, where h and hâ€Č represent a K or π meson and ℓ and ℓâ€Č an electron or muon. The analysis is based on 468 fb−1 of e+e− annihilation data collected at or close to the ΄(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the twelve modes, and we establish 90% confidence level upper limits on the branching fractions in the range (1.0–30.6)×10−7. The limits are between 1 and 3 orders of magnitude more stringent than previous measurements.publishedVersio

    Light meson spectroscopy from Dalitz plot analyses of ηc decays to η0 K+K− , η0 π + π − , and ηπ + π − produced in two-photon interactions

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    We study the processes γγ→ηc→ηâ€ČK+K−, ηâ€Čπ+π−, and ηπ+π− using a data sample of 519  fb−1 recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e+e− collider at center-of-mass energies at and near the ΄(nS) (n=2, 3, 4) resonances. This is the first observation of the decay ηc→ηâ€ČK+K− and we measure the branching fraction Γ(ηc→ηâ€ČK+K−)/(Γ(ηc→ηâ€Čπ+π−)=0.644±0.039stat±0.032sys. Significant interference is observed between γγ→ηc→ηπ+π− and the nonresonant two-photon process ÎłÎłâ†’Î·Ï€+π−. A Dalitz plot analysis is performed of ηc decays to ηâ€ČK+K−, ηâ€Čπ+π−, and ηπ+π−. Combined with our previous analysis of ηc→KÂŻKπ, we measure the K∗0(1430) parameters and the ratio between its ηâ€ČK and πK couplings. The decay ηc→ηâ€Čπ+π− is dominated by the f0(2100) resonance, also observed in J/ψ radiative decays. A new a0(1700)→ηπ resonance is observed in the ηc→ηπ+π− channel. We also compare ηc decays to η and ηâ€Č final states in association with scalar mesons as they relate to the identification of the scalar glueball.publishedVersio

    Measurements of the absolute branching fractions of B± →k±Xc c

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    A study of the two-body decays B±→XcÂŻcK±, where XcÂŻc refers to one charmonium state, is reported by the BABAR Collaboration using a data sample of 424 fb−1. The absolute determination of branching fractions for these decays are significantly improved compared to previous BABAR measurements. Evidence is found for the decay B+→X(3872)K+ at the 3σ level. The absolute branching fraction B[B+→X(3872)K+]=[2.1±0.6(stat)±0.3(syst)]×10−4 is measured for the first time. It follows that B[X(3872)→J/ψπ+π−]=(4.1±1.3)%, supporting the hypothesis of a molecular component for this resonance.publishedVersio

    Head Circumference of Infants Born to Mothers with Different Educational Levels; The Generation R Study

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    Objective: Head circumference (HC) reflect growth and development of the brain in early childhood. It is unknown whether socioeconomic differences in HC are present in early childhood. Therefore, we investigated the association between socioeconomic position (SEP) and HC in early childhood, and potential underlying factors. Methods: The study focused on Dutch children born between April 2002 and January 2006 who participated in The Generation R Study, a population-based prospective cohort study in Rotterdam, the Netherlands. Maternal educational level was used as indicator of SEP. HC measures were concentrated around 1, 3, 6 and 11 months. Associations and explanatory factors were investigated using linear regression analysis, adjusted for potential mediators. Results: The study included 3383 children. At 1, 3 and 6 months of age, children of mothers with a low education had a smaller HC than those with a high education (difference at 1 month: -0.42 SD; 95% CI: -0.54,-0.30; at 3 months: -0.27 SD; 95% CI -0.40,-0.15; and at 6 months: -0.13 SD; 95% CI -0.24,-0.02). Child's length and weight could only partially explain the smaller HC at 1 and 3 months of age. At 6 months, birth weight, gestational age and parental height explained the HC differences. At 11 months, no HC differences were found. Conclusion: Educational inequalities in HC in the first 6 months of life can be mainly explained by pregnancy-related factors, such as birth weight and gestational age. These findings further support public health policies to prevent negative birth outcomes in lower socioeconomic groups

    La filiacion y la fecundacion "in vitro"

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    Las tecnicas de reproduccion asistida no solo representan una solucion para ayudar a superar problemas de esterilidad, sino que su practica conlleva problemas eticos y juridicos. Esta Tesis analiza los problemas que plantea la fecundacion "in vitro", desde el punto de vista de la filiacion, para determinar la paternidad y maternidad cuando se utilizan los gametos de la pareja o de un tercero. Desde este punto de vista, se estudian la situacion juridica del tercero -llamado donante- y de las madres subrogadas, asi como las acciones de filiacion Tambien se examina la problematica que plantea la congelacion de semen y embriones, al poder un hombre engendrar un hijo despues de muerto. Entre las fuentes que se analizan estan los principales informes extranjeros que han estudiado la problematica de estas tecnicas, asi como el Informe especial de..

    Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

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    The production of tt‟ , W+bb‟ and W+cc‟ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓΜ , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of tt‟t\overline{t}, W+bb‟W+b\overline{b} and W+cc‟W+c\overline{c} is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 ±\pm 0.02 \mbox{fb}^{-1}. The WW bosons are reconstructed in the decays W→ℓΜW\rightarrow\ell\nu, where ℓ\ell denotes muon or electron, while the bb and cc quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions

    Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

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    Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a ZZ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 <pT<100< p_{\textrm{T}} < 100 GeV and in the pseudorapidity range 2.5<η<42.5 < \eta < 4. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb−1^{-1}. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages
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