Hadronic Gamma Rays from Supernova Remnants

A gas cloud near a supernova remnant (SNR) provides a target for pp-collisions leading to subsequent gamma-ray emission through neutral pion decay. The assumption of a power-law ambient spectrum of accelerated particles with index near -2 is usually built into models predicting the spectra of very-high energy (VHE) gamma-ray emission from SNRs. However, if the gas cloud is located at some distance from the SNR shock, this assumption is not necessarily correct. In this case, the particles which interact with the cloud are those leaking from the shock and their spectrum is approximately monoenergetic with the injection energy gradually decreasing as the SNR ages. In the GLAST energy range the gamma-ray spectrum resulting from particle interactions with the gas cloud will be flatter than expected, with the cutoff defined by the pion momentum distribution in the laboratory frame. We evaluate the flux of particles escaping from a SNR shock and apply the results to the VHE diffuse emission detected by the HESS at the Galactic centre.Comment: 4 pages, 3 figures. Contribution to the 30th ICRC, Merida, Mexico, 2007 (final version

Ergodicity of the Δ3\Delta_3 statistic and purity of neutron resonance data

The $\Delta_3(L)$ statistic characterizes the fluctuations of the number of levels as a function of the length of the spectral interval. It is studied as a possible tool to indicate the regular or chaotic nature of underlying dynamics, detect missing levels and the mixing of sequences of levels of different symmetry, particularly in neutron resonance data. The relation between the ensemble average and the average over different fragments of a given realization of spectra is considered. A useful expression for the variance of $\Delta_3(L)$ which accounts for finite sample size is discussed. An analysis of neutron resonance data presents the results consistent with a maximum likelihood method applied to the level spacing distribution.Comment: 24 pages, 19 figures, 1 tabl

Strong Shock Waves and Nonequilibrium Response in a One-dimensional Gas: a Boltzmann Equation Approach

We investigate the nonequilibrium behavior of a one-dimensional binary fluid on the basis of Boltzmann equation, using an infinitely strong shock wave as probe. Density, velocity and temperature profiles are obtained as a function of the mixture mass ratio \mu. We show that temperature overshoots near the shock layer, and that heavy particles are denser, slower and cooler than light particles in the strong nonequilibrium region around the shock. The shock width w(\mu), which characterizes the size of this region, decreases as w(\mu) ~ \mu^{1/3} for \mu-->0. In this limit, two very different length scales control the fluid structure, with heavy particles equilibrating much faster than light ones. Hydrodynamic fields relax exponentially toward equilibrium, \phi(x) ~ exp[-x/\lambda]. The scale separation is also apparent here, with two typical scales, \lambda_1 and \lambda_2, such that \lambda_1 ~ \mu^{1/2} as \mu-->0$, while \lambda_2, which is the slow scale controlling the fluid's asymptotic relaxation, increases to a constant value in this limit. These results are discussed at the light of recent numerical studies on the nonequilibrium behavior of similar 1d binary fluids.Comment: 9 pages, 8 figs, published versio

Measurements of the semileptonic decays B[overbar]→Dℓν[overbar] and B[overbar]→D^*ℓν[overbar] using a global fit to DXℓν[overbar] final states

Semileptonic B[overbar] decays to DXℓν[overbar](ℓ=e or μ) are selected by reconstructing D^0ℓ and D^+ℓ combinations from a sample of 230×10^6 Υ(4S)→BB[overbar] decays recorded with the BABAR detector at the PEP-II e^+e^- collider at SLAC. A global fit to these samples in a three-dimensional space of kinematic variables is used to determine the branching fractions B(B^-→D^0ℓν[overbar])=(2.34±0.03±0.13)% and B(B^-→D^(*0)ℓν[overbar])=(5.40±0.02±0.21)% where the errors are statistical and systematic, respectively. The fit also determines form-factor parameters in a parametrization based on heavy quark effective theory, resulting in ρ_D^2=1.20±0.04±0.07 for B[overbar]→Dℓν[overbar] and ρ_(D*)^2=1.22±0.02±0.07 for B[overbar]→D^*ℓν[overbar]. These values are used to obtain the product of the Cabibbo-Kobayashi-Maskawa matrix element |V_(cb)| times the form factor at the zero recoil point for both B[overbar]→Dℓν[overbar] decays, G(1)|V_(cb)|=(43.1±0.8±2.3)×10^(-3), and for B[overbar]→D^*ℓν[overbar] decays, F(1)|V_(cb)|=(35.9±0.2±1.2)×10^(-3)

Measurement of time-dependent CP asymmetry in B^0→K_S^0π^0γ decays

We measure the time-dependent CP asymmetry in B^0→K_S^0π^0γ decays for two regions of K_S^0-π^0 invariant mass, m(KS0π0), using the final BABAR data set of 467×10^6 BB pairs collected at the PEP-II e^+e^- collider at SLAC. We find 339±24 B^0→K^(*0)γ candidates and measure S_(K*γ)=-0.03±0.29±0.03 and C_(K*_γ)=-0.14±0.16±0.03. In the range 1.1<m(K_S^0π^0)<1.8  GeV/c^2 we find 133±20 B^0→K_S^0π^0γ candidates and measure S_(KS^0π^0γ)=-0.78±0.59±0.09 and C_(KS^0π^0γ)=-0.36±0.33±0.04. The uncertainties are statistical and systematic, respectively

The influence of early efficacy beliefs on teams' reactions to failing to reach performance goals

Cataloged from PDF version of article.Although a considerable amount of theoretical and empirical attention has been devoted to understanding individuals' responses to goal–performance discrepancies (GPDs), little attention has been devoted to examining how teams respond to GPDs. The present research sought to examine how teams responded to negative GPDs. We predicted that failing to reach higher goals would be perceived as less negative than failing to reach lower goals, and we examined the moderating influence of setting higher versus lower goals on how teams responded to performance that fell short of those goals. We also examined the role that efficacy beliefs that were formed early in those teams played in further explaining these effects. Results from 94 teams who all failed to reach self-set goals revealed that teams that failed to reach higher goals downwardly revised their goals less than teams that failed to reach lower goals. Early efficacy beliefs further explained these effects. High efficacy beliefs lessened the negative effects of failing to reach lower goals on subsequent goals. High efficacy beliefs also lessened the negative effects of failing to reach higher goals while low efficacy beliefs strengthened the negative effects of failing to reach higher goals. The implications of these findings for theory, research, and practice are discussed

Measurement of branching fractions of B decays to K_1(1270)π and K_1(1400)π and determination of the CKM angle α from B^0→a_1(1260)^±π^∓

We report measurements of the branching fractions of neutral and charged B meson decays to final states containing a K_1(1270) or K_1(1400) meson and a charged pion. The data, collected with the BABAR detector at the SLAC National Accelerator Laboratory, correspond to 454×10^6 BB̅ pairs produced in e^+e^- annihilation. We measure the branching fractions B(B^0→K_1(1270)^+π-+K_1(1400)^+π-)=3.1_(-0.7)^(+0.8)×10^(-5) and B(B^+→K_1(1270)^0π^++K_1(1400)^0π^+)=2.9_(-1.7)^(+2.9)×10^(-5) (<8.2×10^(-5) at 90% confidence level), where the errors are statistical and systematic combined. The B^0 decay mode is observed with a significance of 7.5σ, while a significance of 3.2σ is obtained for the B^+ decay mode. Based on these results, we estimate the weak phase α=(79±7±11)° from the time-dependent CP asymmetries in B^0→a1(1260)^±π^∓ decays

Study of D_(sJ) decays to D*K in inclusive e^+e^- interactions

We observe the decays D*_(s1)(2710)^+ → D*K and D*_(sJ)(2860)^+ → D*K and measure their branching fractions relative to the DK final state. We also observe, in the D*K mass spectrum, a new broad structure at a mass of (3044 ± 8_(stat)(^(+30)_(-5))_(syst))  MeV/c^2 having a width Γ =(239 ± 35_(stat)(^(+46)_(-42))_(syst))  MeV. To obtain this result we use 470  fb^(-1) of data recorded by the BABAR detector at the PEP-II asymmetric-energy e^+e^- storage rings at the Stanford Linear Accelerator Center running at center-of-mass energies near 10.6 GeV