996 research outputs found
Weak Phase gamma Using Isospin Analysis and Time Dependent Asymmetry in B_d -> K_s pi^+ pi^-
We present a method for measuring the weak phase gamma using isospin analysis
of three body B decays into K pi pi channels. Differential decay widths and
time dependent asymmetry in B_d -> K_s pi^+pi^- mode needs to be measured into
even isospin pi pi states. The method can be used to extract gamma, as well as,
the size of the electroweak penguin contributions. The technique is free from
assumptions like SU(3) or neglect of any contributions to the decay amplitudes.
By studying different regions of the Dalitz plot, it is possible to reduce the
ambiguity in the value of gamma.Comment: 11 pages, 1 figur
Characterization of a half-wave plate for cosmic microwave background circular polarization measurement with POLARBEAR
A half-wave plate (HWP) is often used as a modulator to suppress systematic
error in the measurements of cosmic microwave background (CMB) polarization. A
HWP can also be used to measure circular polarization (CP) through its optical
leakage from CP to linear polarization. The CP of the CMB is predicted from
various sources, such as interactions in the Universe and extension of the
standard model. Interaction with supernova remnants of population III stars is
one of the brightest CP sources. Thus, the observation of the CP of CMB is a
new tool for searching for population III stars. In this paper, we demonstrate
the improved measurement of the leakage coefficient using the transmission
measurement of an actual HWP in the laboratory. We measured the transmittance
of linearly polarized light through the HWP used in \textsc{Polarbear} in the
frequency range of \SIrange{120}{160}{GHz}. We evaluate properties of the HWP
by fitting the data with a physical model using the Markov Chain Monte Carlo
method. We then estimate the band-averaged CP leakage coefficient using the
physical model. We find that the leakage coefficient strongly depends on the
spectra of CP sources. We thus calculate the maximum fractional leakage
coefficient from CP to linear polarization as in the
Rayleigh--Jeans spectrum. The nonzero value shows that \textsc{Polarbear} has
sensitivity to CP. Additionally, because we use the bandpass of detectors
installed in the telescope to calculate the band-averaged values, we also
consider systematic effects in the experiment.Comment: 27 pages, 7 figure
Neutral B Flavor Tagging for the Measurement of Mixing-induced CP Violation at Belle
We describe a flavor tagging algorithm used in measurements of the CP
violation parameter sin2phi_1 at the Belle experiment. Efficiencies and wrong
tag fractions are evaluated using flavor-specific B meson decays into hadronic
and semileptonic modes. We achieve a total effective efficiency of $ 28.8 +-
0.6 %.Comment: 28 pages, 9 figure
Ultra High Energy Cosmology with POLARBEAR
Observations of the temperature anisotropy of the Cosmic Microwave Background
(CMB) lend support to an inflationary origin of the universe, yet no direct
evidence verifying inflation exists. Many current experiments are focussing on
the CMB's polarization anisotropy, specifically its curl component (called
"B-mode" polarization), which remains undetected. The inflationary paradigm
predicts the existence of a primordial gravitational wave background that
imprints a unique B-mode signature on the CMB's polarization at large angular
scales. The CMB B-mode signal also encodes gravitational lensing information at
smaller angular scales, bearing the imprint of cosmological large scale
structures (LSS) which in turn may elucidate the properties of cosmological
neutrinos. The quest for detection of these signals; each of which is orders of
magnitude smaller than the CMB temperature anisotropy signal, has motivated the
development of background-limited detectors with precise control of systematic
effects. The POLARBEAR experiment is designed to perform a deep search for the
signature of gravitational waves from inflation and to characterize lensing of
the CMB by LSS. POLARBEAR is a 3.5 meter ground-based telescope with 3.8
arcminute angular resolution at 150 GHz. At the heart of the POLARBEAR receiver
is an array featuring 1274 antenna-coupled superconducting transition edge
sensor (TES) bolometers cooled to 0.25 Kelvin. POLARBEAR is designed to reach a
tensor-to-scalar ratio of 0.025 after two years of observation -- more than an
order of magnitude improvement over the current best results, which would test
physics at energies near the GUT scale. POLARBEAR had an engineering run in the
Inyo Mountains of Eastern California in 2010 and will begin observations in the
Atacama Desert in Chile in 2011.Comment: 8 pages, 6 figures, DPF 2011 conference proceeding
The new generation CMB B-mode polarization experiment: POLARBEAR
We describe the Cosmic Microwave Background (CMB) polarization experiment
called Polarbear. This experiment will use the dedicated Huan Tran Telescope
equipped with a powerful 1,200-bolometer array receiver to map the CMB
polarization with unprecedented accuracy. We summarize the experiment, its
goals, and current status
Study of B -> \rho \pi decays at Belle
This paper describes a study of B meson decays to the pseudoscalar-vector
final state \rho\pi using 31.9\times 10^6 B\bar{B} events collected with the
Belle detector at KEKB. The branching fractions B(B^+ \to \rho^0\pi^+) =
(8.0^{+2.3+0.7}_{-2.0-0.7}) \times 10^{-6} and B(B^0 -> \rho^{+-} \pi^{-+}) =
(20.8^{+6.0+2.8}_{-6.3-3.1}) \times 10^{-6} are obtained. In addition, a 90%
confidence level upper limit of B(B^0 \to \rho^0\pi^0) < 5.3 \times 10^{-6}is
reported.Comment: 14 pages, 3 figures, to be submitted to Phys. Lett.
Measurement of the cosmic microwave background polarization lensing power spectrum from two years of POLARBEAR data
We present a measurement of the gravitational lensing deflection power spectrum reconstructed with two seasons of cosmic microwave background polarization data from the POLARBEAR experiment. Observations were taken at 150 GHz from 2012 to 2014 and surveyed three patches of sky totaling 30 square degrees. We test the consistency of the lensing spectrum with a cold dark matter cosmology and reject the no-lensing hypothesis at a confidence of 10.9σ, including statistical and systematic uncertainties. We observe a value of AL = 1.33 ± 0.32 (statistical) ±0.02 (systematic) ±0.07 (foreground) using all polarization lensing estimators, which corresponds to a 24% accurate measurement of the lensing amplitude. Compared to the analysis of the first- year data, we have improved the breadth of both the suite of null tests and the error terms included in the estimation of systematic contamination
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