Blazar Flaring Rates Measured with GLAST

We derive the minimum observing time scales to detect a blazar at a given flux level with the LAT on GLAST in the scanning and pointing modes. Based upon Phase 1 observations with EGRET, we predict the GLAST detection rate of blazar flares at different flux levels. With some uncertainty given the poor statistics of bright blazars, we predict that a blazar flare with integral flux >~ 200e-8 ph(> 100 MeV) cm^{-2} s^{-1}, which are the best candidates for Target of Opportunity pointings and extensive temporal and spectral studies, should occur every few days.Comment: 7 pages, 2 figures, in 2nd VERITAS Symposium on TeV Astrophysiscs, ed. L. Fortson and S. Swordy, in press, New Astronomy Review

A note on optimal sampling strategy for structural variant detection using optical mapping

Structural variants compose the majority of human genetic variation, but are difficult to accurately assess using current genomic sequencing technologies. Optical mapping technologies, which measure the size of chromosomal fragments between labeled markers, offer an alternative approach. As these technologies mature toward becoming clinical tools, there is a need to develop an approach for determining the optimal strategy for sampling biological material in order to detect a structural variant at some threshold. Here we develop an optimization approach using a simple, yet realistic, model of the genomic mapping process using a hypergeometric distribution and probabilistic concentration inequalities. Our approach is both computationally and analytically tractable and includes a novel approach to getting tail bounds of hypergeometric distribution. We show that if a genomic mapping technology can sample most of the chromosomal fragments within a sample, comparatively little biological material is needed to detect a variant at high confidence

Study of f_0(980) and f_0(1500) from B_s \to f_0(980)\pi, f_0(1500)\pi Decays

In this paper, we analyze the scalar mesons $f_0(980)$ and $f_0(1500)$ from the decays $\bar B^0_s \to f_0(980)\pi^0, f_0(1500)\pi^0$ within Perturbative QCD approach. From the leading order calculations, we find that (a) in the allowed mixing angle ranges, the branching ratio of $\bar B^0_s\to f_0(980)\pi^0$ is about $(1.0\sim1.6)\times 10^{-7}$, which is smaller than that of $\bar B^0_s\to f_0(980)K^0$ (the difference is a few times even one order); (b) the decay $\bar B^0_s \to f_0(1500)\pi^0$ is better to distinguish between the lowest lying state or the first excited state for $f_0(1500)$, because the branching ratios for two scenarios have about one-order difference in most of the mixing angle ranges; and (c) the direct CP asymmetries of $\bar B^0_s \to f_0(1500)\pi^0$ for two scenarios also exists great difference. In scenario II, the variation range of the value ${\cal A} ^{dir}_{CP}(\bar B^0_s \to f_0(1500)\pi^0)$ according to the mixing angle is very small, except for the values corresponding to the mixing angles being near $90^\circ$ or $270^\circ$, while the variation range of ${\cal A} ^{dir}_{CP}(\bar B^0_s \to f_0(1500)\pi^0)$ in scenario I is very large. Compared with the future data for the decay $\bar B^0_s \to f_0(1500)\pi^0$, it is ease to determine the nature of the scalar meson $f_0(1500)$.Comment: 16 pages, 3 figures, Revte

Revisiting the B {\to} {\pi} {\rho}, {\pi} {\omega} Decays in the Perturbative QCD Approach Beyond the Leading Order

We calculate the branching ratios and CP asymmetries of the $B \to \pi \rho$, $\pi\omega$ decays in the perturbative QCD factorization approach up to the next-to-leading-order contributions. We find that the next-to-leading-order contributions can interfere with the leading-order part constructively or destructively for different decay modes. Our numerical results have a much better agreement with current available data than previous leading-order calculations, e.g., the next-to-leading-order corrections enhance the $B^0\rightarrow \pi^0\rho^0$ branching ratios by a factor 2.5, which is helpful to narrow the gaps between theoretic predictions and experimental data. We also update the direct CP-violation parameters, the mixing-induced CP-violation parameters of these modes, which show a better agreement with experimental data than many of the other approaches.Comment: 23 pages, 4 figures, 4 table

Branching ratios of B+→D(∗)+K(∗)0B^+ \to D^{(*)+}K^{(*)0} decays in perturbative QCD approach

We study the rare decays $B^+ \to D^{(*)+}K^{(*)0}$, which can occur only via annihilation type diagrams in the standard model. We calculate all of the four modes, $B \to PP, VP, PV, VV$, in the framework of perturbative QCD approach and give the branching ratios of the order about $10^{-6}$.Comment: 18 pages, 1 figure, Revte

kTk_T factorization of exclusive processes

We prove $k_T$ factorization theorem in perturbative QCD (PQCD) for exclusive processes by considering $\pi\gamma^*\to \gamma(\pi)$ and $B\to\gamma(\pi) l\bar\nu$. The relevant form factors are expressed as the convolution of hard amplitudes with two-parton meson wave functions in the impact parameter $b$ space, $b$ being conjugate to the parton transverse momenta $k_T$. The point is that on-shell valence partons carry longitudinal momenta initially, and acquire $k_T$ through collinear gluon exchanges. The $b$-dependent two-parton wave functions with an appropriate path for the Wilson links are gauge-invariant. The hard amplitudes, defined as the difference between the parton-level diagrams of on-shell external particles and their collinear approximation, are also gauge-invariant. We compare the predictions for two-body nonleptonic $B$ meson decays derived from $k_T$ factorization (the PQCD approach) and from collinear factorization (the QCD factorization approach).Comment: 11 pages, REVTEX, 5 figure

Study of K0∗(1430)K^*_0(1430) and a0(980)a_0(980) from B→K0∗(1430)πB\to K^*_0(1430)\pi and B→a0(980)KB\to a_0(980)K Decays

We use the decay modes $B \to K^*_0(1430) \pi$ and $B \to a_0(980) K$ to study the scalar mesons $K^*_0(1430)$ and $a_0(980)$ within perturbative QCD framework. For $B \to K^*_0(1430) \pi$, we perform our calculation in two scenarios of the scalar meson spectrum. The results indicate that scenario II is more favored by experimental data than scenario I. The important contribution from annihilation diagrams can enhance the branching ratios about 50% in scenario I, and about 30% in scenario II. The predicted branching ratio of $B \to a_0(980) K$ in scenario I is also less favored by the experiments. The direct CP asymmetries in $B \to K^*_0(1430) \pi$ are small, which are consistent with the present experiments.Comment: More references are added. Published Versio

Analysis of Supersymmetric Effects on B -> phi K Decays in the PQCD Approach

We study the effects of the MSSM contribution on B -> phi K decays using the perturbative QCD approach. In this approach, strong phases can be calculated, so that we can predict the values of CP asymmetries with the MSSM contribution. We predict a large relative strong phase between the penguin amplitude and the chromomagnetic penguin amplitude. If there is a new CP violating phase in the chromomagnetic penguin amplitude, then the CP asymmetries may change significantly from the SM prediction. We parametrize the new physics contributions that appear in the Wilson coefficients. We maximize the new physics parameters up to the point where it is limited by experimental constraints. In the case of the LR insertion, we find that the direct CP asymmetries can reach about 85% and the indirect CP asymmetry can reach about -30%.Comment: 18 pages, 9 figures, REVTeX, Minor changes, Version to appear in Phys. Rev.

Nonfactorizable contributions to B→D(∗)MB \to D^{(*)} M decays

While the factorization assumption works well for many two-body nonleptonic $B$ meson decay modes, the recent measurement of $\bar B\to D^{(*)0}M^0$ with $M=\pi$, $\rho$ and $\omega$ shows large deviation from this assumption. We analyze the $B\to D^{(*)}M$ decays in the perturbative QCD approach based on $k_T$ factorization theorem, in which both factorizable and nonfactorizable contributions can be calculated in the same framework. Our predictions for the Bauer-Stech-Wirbel parameters, $|a_2/a_1|= 0.43\pm 0.04$ and $Arg(a_2/a_1)\sim -42^\circ$ and $|a_2/a_1|= 0.47\pm 0.05$ and $Arg(a_2/a_1)\sim -41^\circ$, are consistent with the observed $B\to D\pi$ and $B\to D^*\pi$ branching ratios, respectively. It is found that the large magnitude $|a_2|$ and the large relative phase between $a_2$ and $a_1$ come from color-suppressed nonfactorizable amplitudes. Our predictions for the ${\bar B}^0\to D^{(*)0}\rho^0$, $D^{(*)0}\omega$ branching ratios can be confronted with future experimental data.Comment: 25 pages with Latex, axodraw.sty, 6 figures and 5 tables, Version published in PRD, Added new section 5 and reference