Sudakov effects in BBNS approach

The end-point singularity is an unsolved problem in BBNS approach. Incorporating the partonic transverse momentum and the Sudakov form factor, this problem can be solved model-independently. We discuss the Sudakov effects in BBNS approach. The BBNS approach is compared with the modified PQCD approach. The main idea of Sudakov form factor is briefly discussed. Our conclusion is that the twist-3 contribution for the hard spectator scattering is numerically not important in $B\to \pi\pi$ decays, compared with the twist-2 contribution.Comment: 16 pages, Latex, two figures, some typos correcte

Radiosensitization and growth inhibition of cancer cells mediated by an scFv antibody gene against DNA-PKcs in vitro and in vivo

<p>Abstract</p> <p>Background</p> <p>Overexpression of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is commonly occurred in cancers and causes radioresistance and poor prognosis. In present study, the single-chain variable antibody fragments (scFv) targeting DNA-PKcs was developed for the application of radiosensitization in vitro and in vivo. A humanized semisynthetic scFv library and the phage-display antibodies technology were employed to screen DNA-PKcs scFv antibody.</p> <p>Methods</p> <p>DNA-PKcs epitopes were predicted and cloned. A humanized semisynthetic scFv library and the phage-display antibodies technology were employed to screen DNA-PKcs scFv antibody. DNA damage repair was analyzed by comet assay and immunofluorescence detection of γH2AX foci. The radiosensitization in vivo was determined on Balb/c athymic mice transplanted tumours of HeLa cells.</p> <p>Results</p> <p>Four epitopes of DNA-PKcs have been predicted and expressed as the antigens, and a specific human anti-DNA-PKcs scFv antibody gene, anti-DPK3-scFv, was obtained by screening the phage antibody library using the DNA-PKcs peptide DPK3. The specificity of anti-DPK3-scFv was verified, <it>in vitro</it>. Transfection of HeLa cells with the anti-DPK3-scFv gene resulted in an increased sensitivity to IR, decreased repair capability of DNA double-strand breaks (DSB) detected by comet assay and immunofluorescence detection of γH2AX foci. Moreover, the kinase activity of DNA-PKcs was inhibited by anti-DPK3-scFv, which was displayed by the decreased phosphorylation levels of its target Akt/S473 and the autophosphorylation of DNA-PKcs on S2056 induced by radiation. Measurement of the growth and apoptosis rates showed that anti-DPK3-scFv enhanced the sensitivity of tumours transplanted in Balb/c athymic mice to radiation therapy.</p> <p>Conclusion</p> <p>The antiproliferation and radiosensitizing effects of anti-DPK3-scFv via targeting DNA-PKcs make it very appealing for the development as a novel biological radiosensitizer for cancer therapeutic potential.</p

The systematic study of B→πB\to \pi form factors in pQCD approach and its reliability

The study of exclusive B decays in perturbative QCD are complicated by the endpoint problem. In order to perform the perturbative calculation, the Sudakov effects are introduced to regulate the endpoint singularity. We provide a systematic analysis with leading and next-to-leading twist corrections for $B\to\pi$ form factors in pQCD approach. The intrinsic transverse momentum dependence of hadronic wave function and threshold resummation effects are included in pQCD approach. There are two leading twist B meson distribution amplitudes (or generally wave functions) in general. The QCD equations of motion provide important constraints on B meson wave functions. The reliability of pQCD approach in \bpi form factors is discussed. 70% of the result comes from the region $\alpha_s(t)/\pi<0.2$ and 38% comes from the region where the momentum transfer t\geq 1\GeV. The conceptual problems of pQCD approach are discussed in brief. Our conclusion is that pQCD approach in the present form cannot provide a precise prediction for \bpi transition form factors.Comment: 30 pages, latex, some typos corrected, to appear in Nucl. Phys.

Mass and Decay Constant of I=1/2I=1/2 Scalar Meson In QCD Sum Rule

We calculate the mass and decay constant of $I=1/2$ scalar mesons composed of quark-antiquark pairs based on QCD sum rule. The quauk-antiquark pairs can be $s\bar{q}$ or $q\bar{s}$ ($q=u,d$) in quark model, the quantum numbers of spin and orbital angular momentum are S=1, L=1. We obtain the mass of the ground sate in this channel is $1.410\pm 0.049$GeV. This result favors that $K_{0}^{\ast}(1430)$ is the lowest scalar state of $s\bar{q}$ or $q\bar{s}$. We also predict the first excited scalar resonance of $s\bar{q}$ is larger than 2.0 GeV.Comment: 14 pages, 5 figures, Latex, some content adde

Form Factors and semileptonic decay of Ds+→ϕℓˉνD_s^+\to \phi \bar{\ell}\nu from QCD sum rule

We calculate $D_s^+\to \phi$ transition form factors $V$, $A_0$, $A_1$ and $A_2$, and study semileptonic decay of $D_s^+\to \phi \bar{\ell}\nu$ based on QCD sum rule method. We compare our results of the ratios of $V(0)/A_1(0)$, $A_2(0)/A_1(0)$, $\Gamma_L/\Gamma_T$, and the total decay branching ratio of $D_s^+\to \phi \bar{\ell}\nu$ with experimental data, and find that they are consistent.Comment: version to appear in Eur.Phys.J.

Futher Study of CP Violation and Branching Ratios for B0ˉ→J/ψKs\bar{B^0}\to J/\psi K_s and B0ˉ→ϕKs\bar{B^0}\to \phi K_s in the Standard Model and Beyond

In this work we study the CP violation for $\bar{B^0}\to J/\psi K_s$ and $\bar{B^0}\to \phi K_s$ up to leading and next-to-leading order QCD corrections in the standard model, two-Higgs-doublet model and the minimal supersymmetric extension of the standard model. We also study the effect of new physics on the branching ratios of these two decay modes. We find that within the parameter space constrained by the observation of the decay $b\to s\gamma$, new physics does not affect the CP asymmetries greatly, and the prediction of new physics to the branching ratios of $\bar{B^0}\to J/\psi K_s$ and $\bar{B^0}\to \phi K_s$ is the same as that of the standard model up to a minor discrepancy as far as the Yukama couplying constants are perturbative.Comment: some figures being reduced, accepted by J. Physics

CP-Violation For B→Xsl+l−B \to X_sl^+l^- Including Long-Distance Effects

We consider the CP violating effect for $B\to X_sl^+l^-$ process, including both short and long distance effects. We obtain the CP asymmetry parameter and present its variation over the dilepton mass.Comment: 9 pages, Latex file, one figure include