Diversity of Decline-Rate-Corrected Type Ia Supernova Rise Times: One Mode or Two?

B-band light-curve rise times for eight unusually well-observed nearby Type Ia supernovae (SNe) are fitted by a newly developed template-building algorithm, using light-curve functions that are smooth, flexible, and free of potential bias from externally derived templates and other prior assumptions. From the available literature, photometric BVRI data collected over many months, including the earliest points, are reconciled, combined, and fitted to a unique time of explosion for each SN. On average, after they are corrected for light-curve decline rate, three SNe rise in 18.81 +- 0.36 days, while five SNe rise in 16.64 +- 0.21 days. If all eight SNe are sampled from a single parent population (a hypothesis not favored by statistical tests), the rms intrinsic scatter of the decline-rate-corrected SN rise time is 0.96 +0.52 -0.25 days -- a first measurement of this dispersion. The corresponding global mean rise time is 17.44 +- 0.39 days, where the uncertainty is dominated by intrinsic variance. This value is ~2 days shorter than two published averages that nominally are twice as precise, though also based on small samples. When comparing high-z to low-z SN luminosities for determining cosmological parameters, bias can be introduced by use of a light-curve template with an unrealistic rise time. If the period over which light curves are sampled depends on z in a manner typical of current search and measurement strategies, a two-day discrepancy in template rise time can bias the luminosity comparison by ~0.03 magnitudes.Comment: As accepted by The Astrophysical Journal; 15 pages, 6 figures, 2 tables. Explanatory material rearranged and enhanced; Fig. 4 reformatte

Nonlinear Decline-Rate Dependence and Intrinsic Variation of Type Ia Supernova Luminosities

Published B and V fluxes from nearby Type Ia supernovae are fitted to light-curve templates with 4-6 adjustable parameters. Separately, B magnitudes from the same sample are fitted to a linear dependence on B-V color within a post-maximum time window prescribed by the CMAGIC method. These fits yield two independent SN magnitude estimates B_max and B_BV. Their difference varies systematically with decline rate Delta m_15 in a form that is compatible with a bilinear but not a linear dependence; a nonlinear form likely describes the decline-rate dependence of B_max itself. A Hubble fit to the average of B_max and B_BV requires a systematic correction for observed B-V color that can be described by a linear coefficient R = 2.59 +- 0.24, well below the coefficient R_B ~ 4.1 commonly used to characterize the effects of Milky Way dust. At 99.9% confidence the data reject a simple model in which no color correction is required for SNe that are clustered at the blue end of their observed color distribution. After systematic corrections are performed, B_max and B_BV exhibit mutual rms intrinsic variation equal to 0.074 +- 0.019 mag, of which at least an equal share likely belongs to B_BV. SN magnitudes measured using maximum-luminosity or CMAGIC methods show comparable rms deviations of order ~ 0.14 mag from the Hubble line. The same fit also establishes a 95% confidence upper limit of 486 km/s on the rms peculiar velocity of nearby SNe relative to the Hubble flow.Comment: 21 pages, 11 figures, 10 tables, to appear in The Astrophysical Journal, uses emulateapj_051214.cl

REVIEW OF NEW RESULTS ON MULTILEPTON PRODUCTION BY MUONS

New multimuon data primarily from the Berkeley-Fermi lab-Princeton and European Muon Collaborations are reviewed. Relative to elastic muoproduction of J/{psi}(3100), {psi} events produced at finite but low inelasticity are distributed steeper in {nu} and Q{sup 2} and flatter in -t. The transverse polarization of elastically produced {psi} final states is oriented as expected from s-channel helicity conservation, but gives way to substantial longitudinal polarization at Q{sup 2}<2(GeV/c){sup 2}. At 209 GeV, the diffractive open-charm muoproduction cross section is 6.9{sup +1.9}{sub -1.4) nb, and the Q{sup 2}{rt_arrow}0 photon cross sections are 750{sup +180}{sub -130} (560{sup 200}{sub -120}) nb at 178(100) Gev: The {psi} data and open-charm data both with single and double charm decay to muons generally confirm the photon-gluon-fusion model predictions. Diffractive charm production accounts for ~1/3 of the scale-noninvariance observed in muon-nucleon scattering at low Bjorken x

Top quark results from D-Zero

This is a brief summary of D0's top quark measurements, including {sigma}{sub t{bar t}} and m{sub t} in the {ell} + jets and dilepton channels, {sigma}{sub t{bar t}} in the all jets channel, and the search for top disappearance via t {yields} bH{sup +}, H{sup +} {yields} {tau}{nu} or c{bar s}

REVIEW OF NEW RESULTS ON MULTILEPTON PRODUCTION BY MUONS

New multimuon data primarily from the Berkeley-Fermi lab-Princeton and European Muon Collaborations are reviewed. Relative to elastic muoproduction of J/{psi}(3100), {psi} events produced at finite but low inelasticity are distributed steeper in {nu} and Q{sup 2} and flatter in -t. The transverse polarization of elastically produced {psi} final states is oriented as expected from s-channel helicity conservation, but gives way to substantial longitudinal polarization at Q{sup 2}<2(GeV/c){sup 2}. At 209 GeV, the diffractive open-charm muoproduction cross section is 6.9{sup +1.9}{sub -1.4) nb, and the Q{sup 2}{rt_arrow}0 photon cross sections are 750{sup +180}{sub -130} (560{sup 200}{sub -120}) nb at 178(100) Gev: The {psi} data and open-charm data both with single and double charm decay to muons generally confirm the photon-gluon-fusion model predictions. Diffractive charm production accounts for ~1/3 of the scale-noninvariance observed in muon-nucleon scattering at low Bjorken x