Transfer of Gravitational Information through a Quantum Channel

Gravitational information is incorporated into an atomic state by correlation of the internal and external degrees of freedom of the atom, in the present study of the atomic interferometer. Thus it is difficult to transfer information by using a standard teleportation scheme. In this paper, we propose a novel scheme for the transfer of gravitational information through a quantum channel provided by the entangled atomic state. Significantly, the existence of a quantum channel suppresses phase noise, improving the sensitivity of the atomic interferometer. Thus our proposal provides novel readout mechanism for the interferometer with an improved signal-to-noise ratio

Lepton flavor violating processes in unparticle physics

We study the virtual effects of unparticle physics in the lepton flavor violating processes $M^0\to l^+l'^-$ and $e^+e^-\to l^+l'^-$ scattering, where $M^0$ denotes the pseudoscalar mesons: $\pi^0,K_L, D_0,B_0,B_s^0$ and $l,l'$ denote two different lepton flavors. For the decay of $B^0\to l^+l'^-$, there is no constraint from the current experimental upper bounds on the vector unparticle coupling with leptons. The constraint on the coupling constant between scalar unparticle field and leptons is sensitive to the scaling dimension of the unparticle $d_{\cal U}$. For the scattering process $e^-e^+\to l^-l'^+$, there is only constraint from experiments on the vector unparticle couplings with leptons but no constraint on the scalar unparticle. We study the $\sqrt s$ dependence of the cross section $\frac{1}{\sigma} \frac{d\sigma}{d\sqrt s}$ of $e^+e^-\to l^-l'^+$ with different values of $d_{\cal U}$. If $d_{\cal U}=1.5$, the cross section is independent on the center mass energy. For $d_{\cal U}>1.5$, the cross section increases with $\sqrt s$.Comment: 8 pages, revtex4,with 2 figures, to appear in Phys. Rev.

Perturbative corrections to B→DB \to D form factors in QCD

We compute perturbative QCD corrections to $B \to D$ form factors at leading power in $\Lambda/m_b$, at large hadronic recoil, from the light-cone sum rules (LCSR) with $B$-meson distribution amplitudes in HQET. QCD factorization for the vacuum-to-$B$-meson correlation function with an interpolating current for the $D$-meson is demonstrated explicitly at one loop with the power counting scheme $m_c \sim {\cal O} \left (\sqrt{\Lambda \, m_b} \right )$. The jet functions encoding information of the hard-collinear dynamics in the above-mentioned correlation function are complicated by the appearance of an additional hard-collinear scale $m_c$, compared to the counterparts entering the factorization formula of the vacuum-to-$B$-meson correction function for the construction of $B \to \pi$ from factors. Inspecting the next-to-leading-logarithmic sum rules for the form factors of $B \to D \ell \nu$ indicates that perturbative corrections to the hard-collinear functions are more profound than that for the hard functions, with the default theory inputs, in the physical kinematic region. We further compute the subleading power correction induced by the three-particle quark-gluon distribution amplitudes of the $B$-meson at tree level employing the background gluon field approach. The LCSR predictions for the semileptonic $B \to D \ell \nu$ form factors are then extrapolated to the entire kinematic region with the $z$-series parametrization. Phenomenological implications of our determinations for the form factors $f_{BD}^{+, 0}(q^2)$ are explored by investigating the (differential) branching fractions and the $R(D)$ ratio of $B \to D \ell \nu$ and by determining the CKM matrix element $|V_{cb}|$ from the total decay rate of $B \to D \mu \nu_{\mu}$.Comment: 49 pages, 8 figures, version accepted for publication in JHE