Predictions for B→KγγB \to K \gamma \gamma decays

We present a phenomenological study of the rare double radiative decay $B\to K \gamma\gamma$ in the Standard Model (SM) and beyond. Using the operator product expansion (OPE) technique, we estimate the short-distance (SD) contribution to the decay amplitude in a region of the phase space which is around the point where all decay products have energy $\sim m_b/3$ in the rest frame of the $B$-meson. At lowest order in 1/Q, where $Q$ is of order $m_b$, the $B\to K \gamma\gamma$ matrix element is then expressed in terms of the usual $B\to K$ form factors known from semileptonic rare decays. The integrated SD branching ratio in the SM in the OPE region turns out to be $\Delta {\cal{B}}(B \to K \gamma \gamma)_{SM}^{OPE} \simeq 1 \times 10^{-9}$. We work out the di-photon invariant mass distribution with and without the resonant background through $B\to K \{\eta_c,\chi_{c0}\}\to K\gamma \gamma$. In the SM, the resonance contribution is dominant in the region of phase space where the OPE is valid. The present experimental upper limit on $B_s \to \tau^+ \tau^-$ decays, which constrains the scalar/pseudoscalar Four-Fermi operators with $\tau^+ \tau^-$, leaves considerable room for new physics in the one-particle-irreducible contribution to $B\to K \gamma \gamma$ decays. In this case, we find that the SD $B\to K \gamma \gamma$ branching ratio can be enhanced by one order of magnitude with respect to its SM value and the SD contribution can lie outside of the resonance peaks.Comment: 17 pages, 4 figures; Note added on Schouten identity and 2 references added; v4: typos in Eqs (8), (44) and erroneous statement on mixing before Eq (44) fixed. All results and conclusions unchange

Stability of metallic stripes in the extended one-band Hubbard model

Based on an unrestricted Gutzwiller approximation (GA) we investigate the stripe orientation and periodicity in an extended one-band Hubbard model. A negative ratio between next-nearest and nearest neighbor hopping t'/t, as appropriate for cuprates, favors partially filled (metallic) stripes for both vertical and diagonal configurations. At around optimal doping diagonal stripes, site centered (SC) and bond centered (BC) vertical stripes become degenerate suggesting strong lateral and orientational fluctuations. We find that within the GA the resulting phase diagram is in agreement with experiment whereas it is not in the Hartree-Fock approximation due to a strong overestimation of the stripe filling. Results are in agreement with previous calculations within the three-band Hubbard model but with the role of SC and BC stripes interchanged.Comment: 10 pages, 8 figure

Upper critical field for underdoped high-T_c superconductors. Pseudogap and stripe--phase

We investigate the upper critical field in a stripe--phase and in the presence of a phenomenological pseudogap. Our results indicate that the formation of stripes affects the Landau orbits and results in an enhancement of $H_{c2}$. On the other hand, phenomenologically introduced pseudogap leads to a reduction of the upper critical field. This effect is of particular importance when the magnitude of the gap is of the order of the superconducting transition temperature. We have found that a suppression of the upper critical field takes place also for the gap that originates from the charge--density waves.Comment: 7 pages, 5 figure

Systematic Cu-63 NQR studies of the stripe phase in La(1.6-x)Nd(0.4)Sr(x)CuO(4) for 0.07 <= x <= 0.25

We demonstrate that the integrated intensity of Cu-63 nuclear quadrupole resonance (NQR) in La(1.6-x)Nd(0.4)Sr(x)CuO(4) decreases dramatically below the charge-stripe ordering temperature T(charge). Comparison with neutron and X-ray scattering indicates that the wipeout fraction F(T) (i.e. the missing fraction of the integrated intensity of the NQR signal) represents the charge-stripe order parameter. The systematic study reveals bulk charge-stripe order throughout the superconducting region 0.07 <= x <= 0.25. As a function of the reduced temperature t = T/T(charge), the temperature dependence of F(t) is sharpest for the hole concentration x=1/8, indicating that x=1/8 is the optimum concentration for stripe formation.Comment: 10 pages of text and captions, 11 figures in postscript. Final version, with new data in Fig.

Prenatal Alcohol Exposure in Relation to Autism Spectrum Disorder: Findings from the Study to Explore Early Development (SEED)

Background: Prenatal alcohol exposure can affect neurodevelopment, but few studies have examined associations with autism spectrum disorder (ASD). Methods: We assessed the association between maternal alcohol use and ASD in the Study to Explore Early Development, a multi-site case–control study of children born between September 2003 and August 2006 in the US Regression analyses included 684 children with research clinician-confirmed ASD, 869 children with non-ASD developmental delays or disorders (DDs), and 962 controls ascertained from the general population (POP). Maternal alcohol exposure during each month from 3 months prior to conception until delivery was assessed by self-report. Results: Mothers of POP children were more likely to report any prenatal alcohol use than mothers of children with ASD or DD. In trimester one, 21.2% of mothers of POP children reported alcohol use compared with 18.1% and 18.2% of mothers of children with ASD or DD, respectively (adjusted OR for ASD vs. POP 0.8, 95% confidence interval 0.6, 1.1). During preconception and the first month of pregnancy, one to two drinks on average per week was inversely associated with ASD risk. Conclusions: These results do not support an adverse association between low-level alcohol exposure and ASD, although these findings were based on retrospective self-reported alcohol use. Unmeasured confounding or exposure misclassification may explain inverse associations with one to two drinks per week. Pregnant or potentially pregnant women should continue to follow recommendations to avoid alcohol use because of other known effects on infant health and neurodevelopment

Preschool Children and Behaviour Problems: A Prospective Study

Toddler/child behaviour problems have received relatively little previous attention. Prior studies have implicated a wide variety of factors in the aetiology of child behaviour problems but many of these factors are correlated and little is known about their independent contributions. Four broad categories of factors have been associated with child behaviour problems: (1) maternal social and economic characteristics; (2) maternal lifestyle; (3) maternal mental state/child-rearing practices; and (4) maternal and child physical health. The study took a sample of 5296 families from the Mater-University of Queensland Study of Pregnancy (MUSP) for whom 5-year prospective data are available. The major predictors of toddler behaviour problems were the mother's and child's health, and the mother's mental state. The mother's sociostructural characteristics and lifestyle made little or no additional contribution to the prediction models. It is, however, salutary to note that the majority of children who are classified as having high levels of troublesome behaviour do not fall into any of the risk categories. A variety of explanations and interpretations of the data is considered

B -> X_s gamma gamma and B_s -> gamma gamma in supersymmetry with broken R-parity

We examine the effects of R-parity violating (RPV) supersymmetry on the two-photon B decays B -> X_s gamma gamma and B_s -> gamma gamma. We find that, although there are many one-loop RPV diagrams that can contribute to these two-photon B decays, the RPV effect is dominated by a single diagram. This diagram, named here lambda-irreducible, has a distinct topology which is irrelevant for the b -> s gamma amplitude at one-loop and has thus a negligible effect on the one-photon decay B -> X_s gamma. We show that the lambda-irreducible RPV diagram can give BR(B_s -> gamma gamma) ~ 5*10^(-6) and BR(B -> X_s gamma gamma) ~ 6*10^(-7), which is about 16 and 5 times larger than the SM values, respectively. Although the enhancement to the decay width of B -> X_s gamma gamma is not that dramatic, we find that the energy distribution of the two photons is appreciably different from the SM, due to new threshold effects caused by the distinct topology of the RPV lambda-irreducible diagram. Moreover, this diagram significantly changes the forward-backward asymmetry with respect to the softer photon in B -> X_s gamma gamma. Thus, the RPV effect in B -> X_s gamma gamma can be discerned using these observables.Comment: 12 pages, 6 figure

An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types