78,055 research outputs found

    Light Front Approach for Strong and Weak Decays of Pentaquarks

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    Strong and weak decays of pentaquarks are studied in the framework of the light-front approach.Comment: 3 pages, talk given at the 2004 DPF Meeting, Riverside, CA. Aug 26-31, 200

    Possibly New Charmed Baryon States from Bˉ0ppˉD0\bar B^0\to p\bar p D^{0} Decay

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    We examine the invariant mass spectrum of D0pD^{0}p in Bˉ0ppˉD0\bar B^0\to p\bar p D^{0} decay measured by BABAR and find that through the 2-step processes of Bˉ0Bc+(D0p)pˉ\bar B^0\to {\bf B_c^+}(\to D^{0} p)\bar p, where Bc{\bf B_c} denotes a charmed baryon state, some of the peaks can be identified with the established Σc(2800)+\Sigma_c(2800)^+, Λc(2880)+\Lambda_c(2880)^+ and Λc(2940)+\Lambda_c(2940)^+. Moreover, in order to account for the measured spectrum, it is necessary to introduce a new charmed baryon resonance with (m,Γ)=(3212±20,167±34)(m,\,\Gamma)=(3212\pm 20,\,167\pm 34) MeV.Comment: 8 pages, 1 figure, title changed and discussions updated, version accepted for publication in Phys. Rev.

    Use of active control systems to improve bending and rotor flapping response of a tilt rotor VTOL airplane

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    The results are summarized of an analytical study of the use of active control systems for the purpose of reducing the root mean square response of wing vertical bending and rotor flapping to atmospheric turbulence for a tilt-rotor VTOL airplane. Only the wing/rotor assembly was considered so that results of a wind tunnel test program would be applicable in a subsequent phase of the research. The capabilities and limitations of simple single feedback configurations were identified, and the most promising multiloop feedback configurations were then investigated. Design parameters were selected so as to minimize either wing bending or rotor flapping response. Within the constraints imposed by practical levels of feedback gains and complexity and by considerations of safety, reduction in response due to turbulence of the order of 30 to 50 percent is predicted using the rotor longitudinal cyclic and a trailing edge wing flap as control effectors

    Implications of Recent Bˉ0D()0X0\bar{B}^0\to D^{(*)0}X^0 Measurements

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    The recent measurements of the color-suppressed modes Bˉ0D()0π0\bar B^0\to D^{(*)0}\pi^0 imply non-vanishing relative final-state interaction (FSI) phases among various BˉDπ\bar B\to D\pi decay amplitudes. Depending on whether or not FSIs are implemented in the topological quark-diagram amplitudes, two solutions for the parameters a1a_1 and a2a_2 are extracted from data using various form-factor models. It is found that a2a_2 is not universal: a2(Dπ)=0.400.55|a_2(D\pi)|= 0.40-0.55 and a2(Dπ)=0.250.35|a_2(D^*\pi)|= 0.25-0.35 with a relative phase of order (5055)(50-55)^\circ between a1a_1 and a2a_2. If FSIs are not included in quark-diagram amplitudes from the outset, a2eff/a1effa_2^{eff}/a_1^{eff} and a2effa_2^{eff} will become smaller. The large value of a2(Dπ)|a_2(D\pi)| compared to a2eff(Dπ)|a_2^{eff}(D\pi)| or naive expectation implies the importance of long-distance FSI contributions to color-suppressed internal WW-emission via final-state rescatterings of the color-allowed tree amplitude.Comment: 17 pages. The Introduction is substantially revised and the order of the presentation in Sec. 2 is rearranged. To appear in Phys. Re

    Final stare interaction enhancement effect on the near threshold p\bar p system in B^\pm\to p\bar p \p^\pm decay

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    We discuss the low-mass enhancement effect in the baryon-antibaryon invariant mass in three-body baryonic B decays using final state interactions in the framework of Regge theory. We show that the rescattering between baryonic pair can reproduce the observed mass spectrum.Comment: 7 pages, 11 figure

    An extension of tribimaximal lepton mixing

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    Harrison, Perkins and Scott have proposed simple charged lepton and neutrino mass matrices that lead to the tribimaximal mixing UTBMU_{\rm TBM}. We consider in this work an extension of the mass matrices so that the leptonic mixing matrix becomes UPMNS=VLUTBMWU_{\rm PMNS}=V_L^{\ell\dagger}U_{\rm TBM}W, where VLV_L^\ell is a unitary matrix needed to diagonalize the charged lepton mass matrix and WW measures the deviation of the neutrino mixing matrix from the bimaximal form. Hence, corrections to UTBMU_{\rm TBM} arise from both charged lepton and neutrino sectors. Following our previous work to assume a Qin-Ma-like parametrization VQMV_{\rm QM} for the charged lepton mixing matrix VLV_L^\ell in which the {\it CP}-odd phase is approximately maximal, we study the phenomenological implications in two different scenarios: VL=VQMV_L^\ell=V_{\rm QM}^\dagger and VL=VQMV_L^\ell=V_{\rm QM}. We find that the latter is more preferable, though both scenarios are consistent with the data within 3σ3\sigma ranges. The predicted reactor neutrino mixing angle θ13\theta_{13} in both scenarios is consistent with the recent T2K and MINOS data. The leptonic {\it CP} violation characterized by the Jarlskog invariant JCPJ_{\rm CP} is generally of order 10210^{-2}.Comment: 20 pages and 8 figures, Accepted in Phys.Review