1,679,800 research outputs found

    B + B BARCELONA

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    Tématem projektu je stavba nového gymnázia v Barceloně, v místě, které je typické svými pravidelnými bloky navrženými architektem Cerdou. Stavbu jsem navrhla s respektem k tvaru parcely. Mým cílem bylo, nevytvořit jen vzdělávací budovu pro studenty, ale také kulturní a společenské centrum pro lidi z okolí. Urbanisticky je parcela koncipovaná jako město samo o sobě, které zve kolemjdoucí k návštěvě. Zůstalo příjemné měřítko pro život.The subjekt of the project is the building of a new secondary school in Barcelona, the place, which is typical with his regular piles designed by architekt Cerda. I projected the building with the respect of the shape of site. My tendency was to not only make a educational building for students, but also the cultural and social centre for local inhabitants. The site is conceived as a small city, which invites passers-by to a visit. The pleasant scale factor stayed on.

    Survival probabilities in the double trapping reaction A +B -> B, B + C -> C

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    We consider the double trapping reaction A + B -> B, B + C -> C in one dimension. The survival probability of a given A particle is calculated under various conditions on the diffusion constants of the reactants, and on the ratio of initial B and C particle densities. The results are of more general form than those obtained in previous work on the problem.Comment: 5 page

    A magnetic reconnection model for explaining the multi-wavelength emission of the microquasars Cyg X-1 and Cyg X-3

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    Recent studies have indicated that cosmic ray acceleration by a first-order Fermi process in magnetic reconnection current sheets can be efficient enough in the surrounds of compact sources. In this work, we discuss this acceleration mechanism operating in the core region of galactic black hole binaries (or microquasars) and show the conditions under which this can be more efficient than shock acceleration. In addition, we compare the corresponding acceleration rate with the relevant radiative loss rates obtaining the possible energy cut-off of the accelerated particles and also compute the expected spectral energy distribution (SED) for two sources of this class, namely Cygnus X-1 and Cygnus X-3, considering both leptonic and hadronic processes. The derived SEDs are comparable to the observed ones in the low and high energy ranges. Our results suggest that hadronic non-thermal emission due to photo-meson production may produce the very high energy gamma-rays in these microquasars.Comment: 17 pages and 7 figures. Accepted for publication in the Monthly Notices of the Royal Astronomical Society (MNRAS

    Study of e+e- => B(*) B(*)-bar pi+- at sqrt(s)=10.866 GeV

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    We report the analysis of the three-body e+e- => B B-bar pi, B B*-bar pi, and B* B*-bar pi processes, including the first observation of the Zb+-(10610) =>[B B*-bar+c.c.]+- and Zb+-(10650) => [B*B*-bar]+- transitions. We measure visible cross sections for the three-body production of sigma_vis(e+e- => [B B*-bar+c.c.]+-pi-+=(11.2+-1.0(stat.)+-1.2(syst.)) pb and sigma_vis(e+e- => [B*B*-bar]+-pi-+)=(5.61+-0.73(stat.)+-0.66(syst.)) pb and set a 90% C.L. upper limit of sigma_vis(e+e- => [BB-bar]+-pi-+)<2.1 pb. The results are based on a 121.4 1/fb data sample collected with the Belle detector at a center-of-mass energy near the Y(5S) peak.Comment: 8 pages, 2 figure

    Measurement of branching fractions and CP-violating charge asymmetries for B-meson decays to D^(*)D^(*), and implications for the Cabibbo-Kobayashi-Maskawa angle γ

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    We present measurements of the branching fractions and charge asymmetries of B decays to all D^(*)D^(*) modes. Using 232×10^6 BB pairs recorded on the Υ(4S) resonance by the BABAR detector at the e^+e^- asymmetric B factory PEP-II at the Stanford Linear Accelerator Center, we measure the branching fractions B(B^0→D^(*+)D^(*-))=(8.1±0.6±1.0)×10^(-4), B(B^0→D^(*±)D^∓)=(5.7±0.7±0.7)×10^(-4), B(B^0→D^+D^-)=(2.8±0.4±0.5)×10^(-4), B(B^+→D^(*+)D^(*0))=(8.1±1.2±1.2)×10^(-4), B(B^+→D^*+D^0)=(3.6±0.5±0.4)×10^(-4), B(B^+→D^+D^(*0))=(6.3±1.4±1.0)×10^(-4), and B(B^+→D^+D^(0))=(3.8±0.6±0.5)×10^(-4), where in each case the first uncertainty is statistical and the second systematic. We also determine the limits B(B^0→D^(*0)D^(*0))<0.9×10^(-4), B(B^0→D^(*0)D^0)<2.9×10^(-4), and B(B^0→D^0D^0)<0.6×10^(-4), each at 90% confidence level. All decays above denote either member of a charge-conjugate pair. We also determine the CP-violating charge asymmetries A(B^0→D^(*±)D^∓)=0.03±0.10±0.02, A(B^+→D^(*+)D^(*0))=-0.15±0.11±0.02, A(B^+→D^(*+)D^0)=-0.06±0.13±0.02, A(B^+→D^+D^(*0))=0.13±0.18±0.04, and A(B^+→D^+D^0)=-0.13±0.14±0.02. Additionally, when we combine these results with information from time-dependent CP asymmetries in B^0→D^((*)+)D^((*)-) decays and world-averaged branching fractions of B decays to D_s^(*)D^(*) modes, we find the Cabibbo-Kobayashi-Maskawa phase γ is favored to lie in the range (0.07–2.77) radians (with a +0 or +π radians ambiguity) at 68% confidence level

    Search for Inclusive b → sl^+l^-

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    We have searched for the effective flavor changing neutral-current decays b→sl^+l^- using an inclusive method. We set upper limits on the branching ratios B(b→se^+e^-)<5.7×10^(-5), B(b→sμ^+μ^-)<5.8×10^(-5), and B(b→se^±μ^∓)<2.2×10^(-5) [at 90% confidence level (C.L.)]. Combing the dielectron and dimuon decay modes we find B(b→sl^+l^-)<4.2×10^(-5) (at 90% C.L.)

    Nonleptonic charmless two-body BATB \to AT decays

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    In this work we have studied hadronic charmless two-body B decays involving p-wave mesons in final state. We have calculated branching ratios of BATB\to AT decays (where AA and TT denotes a 3P1^3P_1 axial-vector and a tensor meson, respectively), using BTB \to T form factors obtained in the covariant light-front (CLF) approach, and the full effective Hamiltonian. We have obtained that B(B0a1+a2)=42.47×106\mathcal{B}(B^{0} \to a_{1}^{+}a_{2}^{-}) =42.47 \times10^{-6}, B(B+a1+a20)=22.71×106\mathcal{B}(B^{+} \to a_{1}^{+}a_{2}^{0}) = 22.71 \times10^{-6}, B(Bf1K2)=(2.84)×106\mathcal{B}(B \to f_{1}K_{2}^{*}) = (2.8-4) \times 10^{-6} (with f1=,f1(1285),f1(1420)f_{1}=, f_{1}(1285),f_{1}(1420)) for θ3P1=53.2\theta_{^{3}P_{1}} = 53.2^{\circ}, B(Bf1(1420)K2)=(5.916.42)×106\mathcal{B}(B \to f_{1}(1420)K_{2}^{*}) = (5.91-6.42) \times 10^{-6} with θ3P1=27.9\theta_{^{3}P_{1}} = 27.9^{\circ}, B(BK1a2)=(1.75.7)[19.3]×106\mathcal{B}(B \to K_{1}a_{2})= (1.7 - 5.7) [1-9.3] \times10^{-6} for θK1=37[58]\theta_{K_{1}} = -37^{\circ} [-58^{\circ}] where K1=K1(1270),K1(1400)K_1 = K_1(1270), K_1(1400). It seems that these decays can be measured in experiments at BB factories. Additionally, we have found that B(BK1(1270)a2)/B(BK1(1400)a2)\mathcal{B}(B \to K_{1}(1270)a_{2})/\mathcal{B}(B \to K_{1}(1400)a_{2}) and B(Bf1(1420)K2)/B(Bf1(1285)K2)\mathcal{B}(B \to f_1(1420)K_{2}^{*})/\mathcal{B}(B \to f_1(1285)K_{2}^{*}) ratios could be useful to determine numerical values of mixing angles θK1\theta_{K_{1}} and θ3P1\theta_{^{3}P_{1}}, respectively.Comment: 12 page
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