123690941
Pseudo-Goldstone boson corrections to top-quark production at the Fermilab Tevatron in a topcolour-assisted multiscale technicolour model
Using a topcolour-assisted multiscale technicolour model, we calculate the corrections of pseudo-Goldstone bosons (technipions, top pions) to the cross section of the process q→t at the Fermilab Tevatron. Our results show that corrections mainly come from top pions. With reasonable values of the parameters, the correction can increase the total t production cross section σt by as much as 17%. This may provide a window to detect top pions.
119120154
Study of $B_c \to B^{*}$ P, BV Decays with QCD Factorization
The B c → B (*) q P, B q V decays are studied with the QCD factorization approach (where P and V denote pseudoscalar and vector mesons, respectively; q = u, d, and s). Considering the contributions of both current-current and penguin operators, the amplitudes of branching ratios are estimated at the leading approximation. We find that the contributions of the penguin operators are very small due to the serious suppression by the Cabibbo-Kobayashi-Maskawa elements. The most promising decay modes are B c → B (*) s π, B s ρ, which might be easily detected at hadron colliders.
118825098
Spectator scattering and annihilation contributions as a solution to the $\pi K$ and $\pi \pi$ puzzles within QCD factorization approach
The large branching ratios for pure annihilation $\bar{B}_s^0$ $\to$ $\pi^+ \pi^-$ and $\bar{B}_d^0$ $\to$ $K^+ K^-$ decays reported by CDF and LHCb collaborations recently and the so-called ${\pi}K$ and ${\pi}{\pi}$ puzzles indicate that spectator scattering and annihilation contributions are important to the penguin-dominated, color-suppressed tree dominated, and pure annihilation nonleptonic $B$ decays. Combining the available experimental data for $B_{u,d}$ ${\to}$ $\pi \pi$, ${\pi}K$ and $K \bar{K}$ decays, we do a global fit on the spectator scattering and annihilation parameters $X_H({\rho}_H$, ${\phi}_H)$, $X_A^i({\rho}_A^{i},{\phi}_A^{i})$ and $X_A^f({\rho}_A^{f},{\phi}_A^{f})$, which are used to parameterize the endpoint singularity in amplitudes of spectator scattering, nonfactorizable and factorizable annihilation topologies within the QCD factorization framework, in three scenarios for different purpose. Numerically, in scenario II, we get $({\rho}_A^{i},{\phi}_A^{i}[^{\circ}])=(2.88^{+1.52}_{-1.30},-103^{+33}_{-40})$ and $({\rho}_A^{f},{\phi}_A^{f}[^{\circ}])=(1.21^{+0.22}_{-0.25},-40^{+12}_{-8})$ at the $68\%$ confidence level, which are mainly demanded by resolving ${\pi}K$ puzzle and confirm the presupposition that $X_A^i\neq X_A^f$. In addition, correspondingly, the $B$-meson wave function parameter $\lambda_B$ is also fitted to be $0.18^{+0.11}_{-0.08}\, MeV$, which plays an important role for resolving both ${\pi}K$ and $\pi\pi$ puzzles. With the fitted parameters, the QCDF results for observables of $B_{u,d}$ $\to$ $\pi \pi$, $\pi K$ and $K \bar{K}$ decays are in good agreement with experimental measurements. Much more experimental and theoretical efforts are expected to understand the underlying QCD dynamics of spectator scattering and annihilation contributions.
14205678
Phenomenological analysis of B -> PP decays with QCD factorization
In this paper, we study nonleptonic charmless B decays to two light pseudoscalar mesons within the frame of QCD factorization, including the contributions from the chirally enhanced power corrections and weak annihilation. Predictions for the CP-averaged branching ratios and CP-violating asymmetries are given. Within the reasonable range of the parameters, we find that our predictions for the branching ratios of B-->PP are consistent with the present experimental data. But because of the logarithmic divergences at the end points in the hard spectator scatterings and weak annihilation, there are still large uncertainties in these predictions.
122709614
CHARGED TOP-PION CORRECTIONS TO THE TOP QUARK PRODUCTION AT LC IN TC2 THEORY
We discuss the contributions of PGBs (technipions, top-pions) to the top quark production at the high energy e+e- linear collider (LC) experiments in TC2 theory. We find that the corrections to the production cross-section mainly come from top-pions. The corrections of the charged top-pions are significantly large in most of the parameter space. With reasonable value of the parameters, the correction to can reach about 8% which may be detected at LC experiments.
119214722
Study on the properties of the coupling constants of $J/\psi \rightarrow VP$ decays
Basing on the branching fractions of J/\psi \to VP from different experiments, we investigate on the properties of the coupling constants of J/\psi \to VP decays with a model-dependent approach. We find that the octet coupling constant, g_8, of strong interaction is about twice larger than that of the singlet coupling constant g_1; the electromagnetic breaking parameters g^i_E are larger than the mass breaking parameters g^i_M, moreover, the three parameters of electromagnetic effect are about equal, but the three parameters of mass effect are obviously different and their uncertainties are also large; and the phase angle between strong and electromagnetic interaction is in the range of 70^{\circ} \sim 80^{\circ}. It deepens our understanding of the coupling constant of J/\psi \to VP decays.
118555844
Holographic dual of the dyonic Reissner-Nordström black hole
It is shown that the hidden conformal symmetry, namely SO(2,2) ∼ SL(2,R)L × SL(2,R)R symmetry, of the non-extremal dyonic Reissner-Nordstrblack hole can be probed by a charged massless scalar field at low frequencies. The existence of such hidden conformal symmetry suggests that the field theory holographically dual to the 4D Reissner-Nordstrom black hole indeed should be a 2D CFT. Although the associated AdS3 structure does not explicitly appear in the near horizon geometry, the primary parameters of the dual CFT2 can be exactly obtained without the necessity of embedding the 4D Reissner-Nordstrblack hole into 5D spacetime. The duality is further supported by comparing the absorption cross sections and real-time correlators obtained from both the CFT and the gravity sides.
119264101
Novel features of the transport coefficients in Lifshitz black branes
We study the transport coefficients, including the conductivities and shear viscosity of the non-relativistic field theory dual to the Lifshitz black brane with multiple U(1) gauge fields by virtue of the gauge/gravity duality. Focusing on the case of double U(1) gauge fields, we systematically investigate the electric, thermal and thermoelectric conductivities for the dual non-relativistic field theory. In the large frequency regime, we find a nontrivial power law behavior in the electric AC conductivity when the dynamical critical exponent z>1 in (2+1)-dimensional field theory. The relations between this novel feature and the `symmetric hopping model' in condensed matter physics are discussed. In addition, we also show that the Kovtun-Starinets-Son bound for the shear viscosity to the entropy density is not violated by the additional U(1) gauge fields and dilaton in the Lifshitz black brane.
119212173
Note on Chern-Simons term correction to holographic entanglement entropy
From the perspective of AdS/CFT correspondence, we study the gravitational Chern-Simons term correction to the holographic entanglement entropy of CFT on the conformal boundary of asymptotically AdS3 spacetime using the off-shell Euclidean path integral method. We show that, like the BTZ black hole entropy, the holographic entanglement entropy is indeed modified due to the gravitational Chern-Simons term although the bulk geometry does not change.