Charmless two-body B decays: A global analysis with QCD factorization

In this paper, we perform a global analysis of $B \to PP$ and $PV$ decays with the QCD factorization approach. It is encouraging to observe that the predictions of QCD factorization are in good agreement with experiment. The best fit $\gamma$ is around $79^\circ$. The penguin-to-tree ratio $|P_{\pi \pi}/T_{\pi \pi}|$ of $\pi^+ \pi^-$ decays is preferred to be larger than 0.3. We also show the confidence levels for some interesting channels: $B^0 \to \pi^0 \pi^0$, $K^+ K^-$ and $B^+ \to \omega \pi^+$, $\omega K^+$. For $B \to \pi K^\ast$ decays, they are expected to have smaller branching ratios with more precise measurements.Comment: 20 pages, 4 figures, version to appear in Phys. Rev.

More on volume dependence of spectral weight function

Spectral weight functions are easily obtained from two-point correlation functions and they might be used to distinguish single-particle from multi-particle states in a finite-volume lattice calculation, a problem crucial for many lattice QCD simulations. In previous studies, it is shown that the spectral weight function for a broad resonance shares the typical volume dependence of a two-particle scattering state i.e. proportional to $1/L^3$ in a large cubic box of size $L$ while the narrow resonance case requires further investigation. In this paper, a generalized formula is found for the spectral weight function which incorporates both narrow and broad resonance cases. Within L\"uscher's formalism, it is shown that the volume dependence of the spectral weight function exhibits a single-particle behavior for a extremely narrow resonance and a two-particle behavior for a broad resonance. The corresponding formulas for both $A^+_1$ and $T^-_1$ channels are derived. The potential application of these formulas in the extraction of resonance parameters are also discussed

Deformation of Equilibrium Shape of a Vesicle Induced by Injected Flexible Polymers

Using field theoretic approach, we study equilibrium shape deformation of a vesicle induced by the presence of enclosed flexible polymers, which is a simple model of drug delivery system or endocytosis. To evaluate the total free energy of this system, it is necessary to calculate the bending elastic energy of the membrane, the conformation entropy of the polymers and their interactions. For this purpose, we combine phase field theory for the membrane and self-consistent field theory for the polymers. Simulations on this coupled model system for axiosymmetric shapes show a shape deformation of the vesicle induced by introducing polymers into it. We examined the dependence of the stability of the vesicle shape on the chain length of the polymers and the packing ratio of the vesicle. We present a simple model calculation that shows the relative stability of the prolate shape compared to the oblate shape.Comment: 5 pages, 3 figure

Short-term efficacy and usage recommendations for a large-scale implementation of the math-whizz tutor

This paper adds to the evidence of the efficacy of intelligent tutoring systems (ITS) in mathematics learning by evaluating a large-scale intervention at the state of Aguascalientes, Mexico. We report the results of a quasi-experimental study, addressing at the same a particular request of the decision-makers responsible for the rollout to provide, from early stages of the intervention, independent evidence of the efficacy of Math-Whizz Tutor beyond its internal metrics, and recommendations in terms of the expected weekly usage levels to guide the blended learning approach

Coulomb-driven broken-symmetry states in doubly gated suspended bilayer graphene

The non-interacting energy spectrum of graphene and its bilayer counterpart consists of multiple degeneracies owing to the inherent spin, valley and layer symmetries. Interactions among charge carriers are expected to spontaneously break these symmetries, leading to gapped ordered states. In the quantum Hall regime these states are predicted to be ferromagnetic in nature whereby the system becomes spin polarized, layer polarized or both. In bilayer graphene, due to its parabolic dispersion, interaction-induced symmetry breaking is already expected at zero magnetic field. In this work, the underlying order of the various broken-symmetry states is investigated in bilayer graphene that is suspended between top and bottom gate electrodes. By controllably breaking the spin and sublattice symmetries we are able to deduce the order parameter of the various quantum Hall ferromagnetic states. At small carrier densities, we identify for the first time three distinct broken symmetry states, one of which is consistent with either spontaneously broken time-reversal symmetry or spontaneously broken rotational symmetry

A spectral dissimilarity constrained nonnegative matrix factorization based cancer screening algorithm from hyperspectral fluorescence images

Bioluminescence from living body can help screen cancers without penetrating the inside of living body. Hyperspectral imaging technique is a novel way to obtain physical meaningful signatures, providing very fine spectral resolution, that can be very used in distinguishing different kinds of materials, and have been widely used in remote sensing field. Fluorescence imaging has proved effective in monitoring probable cancer cells. Recent work has made great progress on the hyperspectral fluorescence imaging techniques, which makes the elaborate spectral observation of cancer areas possible. So how to propose the proper hyperspectral image processing methods to handle the hyperspectral medical images is of practical importance. Cancer cells would be distinguishable with normal ones when the living body is injected with fluorescence, which helps organs inside the living body emit lights, and then the signals can be catched by the passive imaging sensor. Spectral unmixing technique in hyperspectral remote sensing has been introduced to detect the probable cancer areas. However, since the cancer areas are small and the normal areas and the cancer ares may not pure pixels so that the predefined endmembers would not available. In this case, the classic blind signals separation methods are applicable. Considering the spectral dissimilarity between cancer and normal cells, a novel spectral dissimilarity constrained based NMF method is proposed in this paper for cancer screening from fluorescence hyperspectral images. Experiments evaluate the performance of variable NMF based method and our proposed spectral dissimilarity based NMF methods: 1) The NMF methods do perform well in detect the cancer areas inside the living body; 2) The spectral dissimilarity constrained NMF present more accurate cancer areas; 3) The spectral dissimilarity constraint presents better performance in different SNR and different purities of the mixing endmembers. © 2012 IEEE

A New Method of Measuring 81Kr and 85Kr Abundances in Environmental Samples

We demonstrate a new method for determining the 81Kr/Kr ratio in environmental samples based upon two measurements: the 85Kr/81Kr ratio measured by Atom Trap Trace Analysis (ATTA) and the 85Kr/Kr ratio measured by Low-Level Counting (LLC). This method can be used to determine the mean residence time of groundwater in the range of 10^5 - 10^6 a. It requires a sample of 100 micro-l STP of Kr extracted from approximately two tons of water. With modern atmospheric Kr samples, we demonstrate that the ratios measured by ATTA and LLC are directly proportional to each other within the measurement error of +/- 10%; we calibrate the 81Kr/Kr ratio of modern air measured using this method; and we show that the 81Kr/Kr ratios of samples extracted from air before and after the development of the nuclear industry are identical within the measurement error

(3+2) Neutrino Scheme From A Singular Double See-Saw Mechanism

We obtain a 3+2 neutrino spectrum within a left-right symmetric framework by invoking a singular double see-saw mechanism. Higgs doublets are employed to break $SU_{R}(2)$ and three additional fermions, singlets under the left-right symmetric gauge group, are included. The introduction of a singularity into the singlet fermion Majorana mass matrix results in a light neutrino sector of three neutrinos containing predominantly $\nu_{\alpha L}$, $\alpha=e,\mu,\tau$, separated from two neutrinos containing a small $\nu_{\alpha L}$ component. The resulting active-sterile mixing in the $5\times 5$ mixing matrix is specified once the mass eigenvalues and the $3\times3$ submatrix corresponding to the MNS mixing matrix are known.Comment: 5 pages, matches published versio

Fermi-sea-like correlations in a partially filled Landau level

The pair distribution function and the static structure factor are computed for composite fermions. Clear and robust evidence for a $2k_F$ structure is seen in a range of filling factors in the vicinity of the half-filled Landau level. Surprisingly, it is found that filled Landau levels of composite fermions, i.e. incompressible FQHE states, bear a stronger resemblance to a Fermi sea than do filled Landau levels of electrons.Comment: 23 pages, revte