238 research outputs found

    Revisiting the DD-meson twist-2, 3 distribution amplitudes

    Full text link
    Due to the significant difference between the experimental measurements and the theoretical predictions of standard model (SM) for the value of R(D)\mathcal{R}(D) of the semileptonic decay B→DℓνˉℓB\to D\ell\bar{\nu}_{\ell}, people speculate that it may be the evidence of new physics beyond the SM. Usually, the DD-meson twist-2, 3 distribution amplitudes (DAs) ϕ2;D(x,μ)\phi_{2;D}(x,\mu), ϕ3;Dp(x,μ)\phi_{3;D}^p(x,\mu) and ϕ3;Dσ(x,μ)\phi_{3;D}^\sigma(x,\mu) are the main error sources when using perturbative QCD factorization and light-cone QCD sum rules to study B→DℓνˉℓB\to D\ell\bar{\nu}_{\ell}. Therefore, it is important to get more reasonable and accurate behaviors for those DAs. Motivated by our previous work [Phys. Rev. D 104, no.1, 016021 (2021)] on pionic leading-twist DA, we revisit DD-meson twist-2, 3 DAs ϕ2;D(x,μ)\phi_{2;D}(x,\mu), ϕ3;Dp(x,μ)\phi_{3;D}^p(x,\mu) and ϕ3;Dσ(x,μ)\phi_{3;D}^\sigma(x,\mu). New sum rules formulae for the ξ\xi-moments of these three DAs are suggested to obtain more accurate values. The light-cone harmonic oscillator models for those DAs are improved, and whose model parameters are determined by fitting the values of ξ\xi-moments with the least squares method.Comment: 9 pages, 2 figure

    Investigation for ZZ-boson decay into Ξbc\Xi_{bc} and Ξbb\Xi_{bb} baryon with the NRQCD factorizations approach

    Full text link
    The ZZ-boson decay provides good opportunities for the research on ΞbQβ€²\Xi_{bQ'} baryon due to large quantity of ZZ events that can be collected at the high-energy colliders. We performed a completed investigation of the indirect production of the Ξbc\Xi_{bc} and Ξbb\Xi_{bb} baryon via ZZ-boson decay Zβ†’ΞžbQβ€²+bΛ‰+QΛ‰β€²Z\to \Xi_{bQ'}+\bar b +\bar Q' with Qβ€²=(c,b)Q'= (c, b) quark according to NRQCD factorizations approach. After considering the contribution of the diquark states ⟨bc⟩[3S1]3Λ‰/6\langle bc\rangle [^3S_1]_{\bar 3/6}, ⟨bc⟩[1S0]3Λ‰/6\langle bc\rangle [^1S_0]_{\bar 3/6}, ⟨bb⟩[1S0]6\langle bb\rangle [^1S_0]_{6} and ⟨bb⟩[3S1]3Λ‰\langle bb\rangle [^3S_1]_{\bar 3}, the calculated branching ratio for Zβ†’ΞžbQβ€²+XZ\to\Xi_{bQ'}+X are B(Zβ†’Ξžbc+X)=3.595Γ—10βˆ’5{\cal B}(Z\to\Xi_{bc}+X) = 3.595\times 10^{-5} and B(Zβ†’Ξžbc+X)=1.213Γ—10βˆ’6{\cal B}(Z\to\Xi_{bc}+X) = 1.213\times 10^{-6}. Moreover, the Ξbc\Xi_{bc} events produced are predicted to be of the 104(107)10^4(10^7) order at the LHC(CEPC), while the Ξbb\Xi_{bb} events produced are forecasted to be of the 103(106)10^3(10^6) order. Furthermore, we have estimated the production ratio R(ZQβ†’Ξžbc+,0){\cal R}(Z_Q\to\Xi^{+,0}_{bc}) with four ZZ-boson decay channels. The R(ZQβ†’Ξžbc+,0){\cal R}(Z_Q\to\Xi^{+,0}_{bc}) up to 10βˆ’610^{-6} for Zβ†’ccΛ‰Z\to c\bar c channel and 10βˆ’510^{-5} for Zβ†’bbΛ‰Z\to b\bar b channel, respectively. Finally, we present the differential decay widths of Ξbc(Ξbb)\Xi_{bc}(\Xi_{bb}) with respect to s23s_{23} and zz distributions, and analysis the uncertainties.Comment: 9 pages, 4 figures. Some ambiguous sentences have been modified and discussion extende

    Heavy Pseudoscalar Twist-3 Distribution Amplitudes within QCD Theory in Background Fields

    Full text link
    In this paper, we study the properties of the twist-3 distribution amplitude (DA) of the heavy pseudo-scalars such as Ξ·c\eta_c, BcB_c and Ξ·b\eta_b. New sum rules for the twist-3 DA moments \left_{\rm HP} and \left_{\rm HP} up to sixth orders and up to dimension-six condensates are deduced under the framework of the background field theory. Based on the sum rules for the twist-3 DA moments, we construct a new model for the two twist-3 DAs of the heavy pseudo-scalar with the help of the Brodsky-Huang-Lepage prescription. Furthermore, we apply them to the Bcβ†’Ξ·cB_c\to\eta_c transition form factor (f+Bcβ†’Ξ·c(q2)f^{B_c\to\eta_c}_+(q^2)) within the light-cone sum rules approach, and the results are comparable with other approaches. It has been found that the twist-3 DAs Ο•3;Ξ·cP\phi^P_{3;\eta_c} and Ο•3;Ξ·cΟƒ\phi^\sigma_{3;\eta_c} are important for a reliable prediction of f+Bcβ†’Ξ·c(q2)f^{B_c\to\eta_c}_+(q^2). For example, at the maximum recoil region, we have f+Bcβ†’Ξ·c(0)=0.674Β±0.066f^{B_c\to\eta_c}_+(0) = 0.674 \pm 0.066, in which those two twist-3 terms provide ∼33%\sim33\% and ∼22%\sim22\% contributions. Also we calculate the branching ratio of the semi-leptonic decay Bcβ†’Ξ·clΞ½B_c \to\eta_c l\nu as Br(Bcβ†’Ξ·clΞ½)=(9.31βˆ’2.01+2.27)Γ—10βˆ’3Br(B_c \to\eta_c l\nu) = \left( 9.31^{+2.27}_{-2.01} \right) \times 10^{-3}.Comment: 12 pages, 16 figure

    Further study on the production of P-wave doubly heavy baryons from Z-boson decays

    Full text link
    In this paper, we carried out a systematic investigation about the excited doubly heavy baryons production in ZZ-boson decays within the framework of NRQCD. Our investigation accounts for all the intermediate diquark states, including those in PP-wave such as ⟨cc⟩[1P1]3Λ‰\langle cc\rangle[^1P_1]_{\bar 3}, ⟨cc⟩[3PJ]6\langle cc\rangle[^3P_J]_{6}, ⟨bc⟩[1P1]3Λ‰/6\langle bc\rangle[^1P_1]_{\bar 3/6}, ⟨bc⟩[3PJ]3Λ‰/6\langle bc\rangle[^3P_J]_{\bar 3/6}, ⟨bb⟩[1P1]3Λ‰\langle bb\rangle[^1P_1]_{\bar 3}, and ⟨bb⟩[3PJ]6\langle bb\rangle[^3P_J]_{6} with J=(0,1,2)J = (0, 1, 2), were taken into account. The results show that the contributions of the all diquark state in PP-wave were 7%7\%, 8%8\%, and 3%3\%, respectively, when compared to SS-wave. Based on these results, we anticipate that about 0.539Γ—103(106)0.539\times 10^3(10^6) events of excited Ξcc\Xi_{cc}, 1.827Γ—103(106)1.827\times 10^3(10^6) events of excited Ξbc\Xi_{bc} and 0.036Γ—103(106)0.036\times 10^3(10^6) events of excited Ξbb\Xi_{bb} can be produced annually at the LHC (CEPC). Additionally, we plot the differential decay widths of Ξcc\Xi_{cc}, Ξbc\Xi_{bc} and Ξbb\Xi_{bb} as a function of the invariant mass s23s_{23} and energy fuction zz distributions, and analyze the theoretical uncertainties decay width arising from the mass parameters of heavy quark.Comment: 11 pages, 4 figure

    The D→ρD\to \rho semileptonic and radiative decays within the light-cone sum rules

    Full text link
    The measured branching ratio of the DD meson semileptonic decay D→ρe+Ξ½eD \to \rho e^+ \nu_e, which is based on the 0.82Β fbβˆ’10.82~{\rm fb^{-1}} CLEO data taken at the peak of ψ(3770)\psi(3770) resonance, disagrees with the traditional SVZ sum rules analysis by about three times. In the paper, we show that this discrepancy can be eliminated by applying the QCD light-cone sum rules (LCSR) approach to calculate the D→ρD\to \rho transition form factors A1,2(q2)A_{1,2}(q^2) and V(q2)V(q^2). After extrapolating the LCSR predictions of these TFFs to whole q2q^2-region, we obtain 1/∣Vcd∣2Γ—Ξ“(D→ρeΞ½e)=(55.45βˆ’9.41+13.34)Γ—10βˆ’15Β GeV1/|V_{\rm cd}|^2 \times \Gamma(D \to \rho e \nu_e) =(55.45^{+13.34}_{-9.41})\times 10^{-15}~{\rm GeV}. Using the CKM matrix element and the D0(D+)D^0(D^+) lifetime from the Particle Data Group, we obtain B(D0β†’Οβˆ’e+Ξ½e)=(1.749βˆ’0.297+0.421Β±0.006)Γ—10βˆ’3{\cal B} (D^0\to \rho^- e^+ \nu_e) = (1.749^{+0.421}_{-0.297}\pm 0.006)\times 10^{-3} and B(D+→ρ0e+Ξ½e)=(2.217βˆ’0.376+0.534Β±0.015)Γ—10βˆ’3{\cal B} (D^+ \to \rho^0 e^+ \nu_e) = (2.217^{+0.534}_{-0.376}\pm 0.015)\times 10^{-3}, which agree with the CLEO measurements within errors. We also calculate the branching ratios of the two DD meson radiative processes and obtain B(D0→ρ0Ξ³)=(1.744βˆ’0.704+0.598)Γ—10βˆ’5{\cal B}(D^0\to \rho^0 \gamma)= (1.744^{+0.598}_{-0.704})\times 10^{-5} and B(D+→ρ+Ξ³)=(5.034βˆ’0.958+0.939)Γ—10βˆ’5{\cal B}(D^+ \to \rho^+ \gamma) = (5.034^{+0.939}_{-0.958})\times 10^{-5}, which also agree with the Belle measurements within errors. Thus we think the LCSR approach is applicable for dealing with the DD meson decays.Comment: 12 pages, 7 figures, version to be published in EPJ

    Next-to-leading-order QCD correction to the exclusive double charmonium production via ZZ decays

    Full text link
    In this paper, we preformed a further research on the exclusive productions of double charmonium via ZZ-boson decay by using nonrelativistic QCD factorizations approach, where the single-photon fragmentation topologies of the QED diagrams, the interference terms between the QCD and full QED diagrams, the next-to-leading-order calculations of the interference terms are preformed. For the production of J/ψ+J/ψJ/\psi+J/\psi in ZZ-boson decay, the interference terms show a significantly phenomenological effect due to the addition of the newly calculated NLO QCD corrections. After adding together all contributions, the branching fraction BZβ†’J/ψJ/ψ\mathcal{B}_{Z\to J/\psi J/\psi} still undershoots the CMS collaboration data obviously. In addition, we simultaneously complete the next-to-leading-order calculations for Zβ†’J/ψ+Ξ·c(Ο‡cJ)Z\to J/\psi+\eta_c (\chi_{cJ}) with J=(0,1,2)J=(0,1,2). The calculated results show that the newly-calculated complete QED and cross terms will have obvious effective on the total decay widths.Comment: 8 pages, 4 figure
    • …