1,361 research outputs found

    Hints on the quadrupole deformation of the Δ\Delta(1232)

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    The E2/M1 ratio (EMR) of the Δ\Delta(1232) is extracted from the world data in pion photoproduction by means of an Effective Lagrangian Approach (ELA).This quantity has been derived within a crossing symmetric, gauge invariant, and chiral symmetric Lagrangian model which also contains a consistent modern treatment of the Δ\Delta(1232) resonance. The \textit{bare} s-channel Δ\Delta(1232) contribution is well isolated and Final State Interactions (FSI) are effectively taken into account fulfilling Watson's theorem. The obtained EMR value, EMR=(−1.30±0.52)=(-1.30\pm0.52)%, is in good agreement with the latest lattice QCD calculations [Phys. Rev. Lett. 94, 021601 (2005)] and disagrees with results of current quark model calculations.Comment: Enlarged conclusions and explanations on the E2/M1 ratio. Figure 3 improved. References updated. 5 pages. 3 figures. 2 tables. Accepted for publication in Physical Review

    On the Determination of a1a_1 and a2a_2 from Hadronic Two Body BB Decays

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    {}From Class I decays : B^o \ra \pi^+ ( \rho^+ ) + D^- ( {D^*}^- ), we determine a1a_1, and from Class III decays : B^+ \ra \pi^+ ( \rho^+ ) + \ol{D}^o ( {\ol{D}^*}^o ), we determine an allowed domain in the (a1,a2)( a_1, a_2 ) plane. We find that within one standard deviation errors, the allowed band of a1a_1 from Class I decays is at least three standard deviations removed from the allowed domain (a1,a2)( a_1, a_2 ) from Class III decays.If we expand the experimental errors to two standard deviations we do find a small intersection between the a1a_1 band and the allowed (a1,a2)( a_1, a_2 ) domain. The results usually quoted in the literature lie in this intersection. We suggest : (1) an independent measurement of the branching ratio for the Class III decay, B^+ \ra \rho^+ \ol{D}^o , (2) a high-statistics measurement of the branching ratio of the Class I decay, B \ra \ol{D} ( \ol{D}^* ) + D_s ( D_s^* ) in both charged states, and (3) a measurement of the longitudinal polarization fraction in the Class III decay B^+ \ra \rho^+ {\ol{D}^*}^o to shed more light on the questions involved .Comment: 9pages(Latex)+4 figures(PS file appended), PAR/LPTHE/94-2

    B ->\eta_c K(\eta_c^\prime K) decays in QCD factorization

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    We study the exclusive decays of BB meson into pseudoscalar charmonium states ηc\eta_c and ηc′\eta_c^\prime within the QCD factorization approach and find that the nonfactorizable corrections to naive factorization are infrared safe at leading-twist order. The spectator interactions arising from the kaon twist-3 effects are formally power-suppressed but chirally and logarithmically enhanced. The theoretical decay rates are too small to accommodate the experimental data. On the other hand, we compare the theoretical calculations for J/ψ,ψ′J/\psi, \psi^\prime, and ηc,ηc′\eta_c, \eta_c^\prime, and find that the predicted relative decay rates of these four states are approximately compatible with experimental data.Comment: 8 pages, LaTex, 1 figure, one footnote and two references adde

    Systèmes quasi linéaires hyperboliques non symétrisables

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    Letter, 1852, from Gourdin to Thoms Green Clemson

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    Letter, January 31, 1852, to Thomas Green Clemson

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    Lindsay Anderson: Britishness and national cinemas

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    This article will explore three key stages in Lindsay Anderson’s career that illustrate the complex relationship between the director’s negotiation of his own national background and the imposition of a national identity in the critical reception of his work. First, I will look briefly at Anderson’s early directorial career as a documentary filmmaker: by using references to the Free Cinema movement and Thursday’s Children (1953), I will show that, in both instances, the question of artistic impact and critical reception took on a transnational dimension. I will then discuss the production of a documentary short in Poland, which Anderson filmed at the request of the Documentary Studio in Warsaw in 1967, and which constitutes the director’s first experience of working in a foreign film industry. Finally, I will discuss Britannia Hospital (1982), the last feature film that Anderson made in Britain. Throughout the paper, I will also use material from the Lindsay Anderson Archive held at Stirling University
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