The Simons Observatory: Science goals and forecasts

The Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the scientific goals of the experiment, motivate the design, and forecast its performance. SO will measure the temperature and polarization anisotropy of the cosmic microwave background in six frequency bands: 27, 39, 93, 145, 225 and 280 GHz. The initial configuration of SO will have three small-aperture 0.5-m telescopes (SATs) and one large-aperture 6-m telescope (LAT), with a total of 60,000 cryogenic bolometers. Our key science goals are to characterize the primordial perturbations, measure the number of relativistic species and the mass of neutrinos, test for deviations from a cosmological constant, improve our understanding of galaxy evolution, and constrain the duration of reionization. The SATs will target the largest angular scales observable from Chile, mapping ~10% of the sky to a white noise level of 2 $\mu$K-arcmin in combined 93 and 145 GHz bands, to measure the primordial tensor-to-scalar ratio, $r$, at a target level of $\sigma(r)=0.003$. The LAT will map ~40% of the sky at arcminute angular resolution to an expected white noise level of 6 $\mu$K-arcmin in combined 93 and 145 GHz bands, overlapping with the majority of the LSST sky region and partially with DESI. With up to an order of magnitude lower polarization noise than maps from the Planck satellite, the high-resolution sky maps will constrain cosmological parameters derived from the damping tail, gravitational lensing of the microwave background, the primordial bispectrum, and the thermal and kinematic Sunyaev-Zel'dovich effects, and will aid in delensing the large-angle polarization signal to measure the tensor-to-scalar ratio. The survey will also provide a legacy catalog of 16,000 galaxy clusters and more than 20,000 extragalactic sources

The Simons Observatory: Science goals and forecasts

The Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the scientific goals of the experiment, motivate the design, and forecast its performance. SO will measure the temperature and polarization anisotropy of the cosmic microwave background in six frequency bands centered at: 27, 39, 93, 145, 225 and 280 GHz. The initial configuration of SO will have three small-aperture 0.5-m telescopes and one large-aperture 6-m telescope, with a total of 60,000 cryogenic bolometers. Our key science goals are to characterize the primordial perturbations, measure the number of relativistic species and the mass of neutrinos, test for deviations from a cosmological constant, improve our understanding of galaxy evolution, and constrain the duration of reionization. The small aperture telescopes will target the largest angular scales observable from Chile, mapping 10% of the sky to a white noise level of 2 μK-arcmin in combined 93 and 145 GHz bands, to measure the primordial tensor-to-scalar ratio, r, at a target level of σ(r)=0.003. The large aperture telescope will map 40% of the sky at arcminute angular resolution to an expected white noise level of 6 μK-arcmin in combined 93 and 145 GHz bands, overlapping with the majority of the Large Synoptic Survey Telescope sky region and partially with the Dark Energy Spectroscopic Instrument. With up to an order of magnitude lower polarization noise than maps from the Planck satellite, the high-resolution sky maps will constrain cosmological parameters derived from the damping tail, gravitational lensing of the microwave background, the primordial bispectrum, and the thermal and kinematic Sunyaev-Zel'dovich effects, and will aid in delensing the large-angle polarization signal to measure the tensor-to-scalar ratio. The survey will also provide a legacy catalog of 16,000 galaxy clusters and more than 20,000 extragalactic sources

The BaBar detector

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Search for radiative b-hadron decays in p(p)over-bar collisions at root s=1.8 TeV RID C-1693-2008 RID A-5169-2010 RID E-4473-2011 RID C-2406-2008

We have performed a search for radiative b-hadron decays using events produced in p (p) over bar collisions at roots=1.8 TeV and collected by the Collider Detector at Fermilab. The decays we considered were (B) over bar (0)(d)-->(K) over bar*(0)(-->K(-)pi(+))gamma, (B) over bar (0)(s)-->phi(-->K+K-)gamma, Lambda(b)(0)-->Lambda(-->ppi(-))gamma, and their charge conjugates. Two independent methods to identify photons from such decays were employed. In the first method, the photon was detected in the electromagnetic calorimeter. In the second method, the photon was identified by an electron-positron pair produced through the external photon conversion before the tracking detector volume. By combining the two methods we obtain upper limits on the branching fractions for the (B) over bar (0)(d), (B) over bar (0)(s), and Lambda(b)(0) radiative decays which, at the 95% confidence level, are found to be B((B) over bar (0)(d)-->(K) over bar*(0)gamma)phigamma)Lambdagamma)<1.9x10(-3)

Measurement of the CKM matrix element |V(ub)| with B ---> rho e nu decays

We present a measurement of the branching fraction for the rare decays B->rho e nu and extract a value for the magnitude of Vub, one of the smallest elements of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix. The results are given for five different calculations of form factors used to parametrize the hadronic current in semileptonic decays. Using a sample of 55 million BBbar meson pairs recorded with the BABAR detector at the PEP-II e+e- storage ring, we obtain Br(B0->rho- e+ nu)=(3.29 +-0.42 +-0.47 +-0.60) x 10^-4 and |Vub|=(3.64 +-0.22 +-0.25 +0.39-0.56)x10^-3, where the uncertainties are statistical, systematic, and theoretical, respectively.Comment: Submitted to Phys. Rev. Let

Measurement of B0 ---> D(*)+ D*- branching fractions and B0 ---> D*+(s) D*- polarization with a partial reconstruction technique

We present a study of the decays B0->D_s(*)+D*-, using 20.8 fb-1 of e+e- annihilation data recorded with the BABAR detector. The analysis is conducted with a partial reconstruction technique, in which only the D_s(*)+ and the soft pion from the D*- decay are reconstructed. We measure the branching fractions BR(B0->D_s+D*-) = (1.03 +/- 0.14 +/- 0.13 +/- 0.26)% and BR(B0->D_s*+D*-) = (1.97 +/- 0.15 +/- 0.30 +/- 0.49)%, where the first error is statistical, the second is systematic, and the third is the error due to the D_s+->phi pi+ branching fraction uncertainty. From the B0->D_s*+D*- angular distributions, we measure the fraction of longitudinal polarization Gamma_L/Gamma = (51.9 +/- 5.0 +/- 2.8)%, which is consistent with theoretical predictions based on factorization.Comment: 9 pages, 4 postscript figues, submitted to Physical Review D (Rapid Communications

Measurement of time-dependent CP asymmetries and the CP-odd fraction in the decay B-0 -> D*+D*- RID C-2728-2008 RID C-5223-2009 RID C-5719-2008 RID D-1055-2009 RID A-2675-2009

We present a measurement of time-dependent CP asymmetries and an updated determination of the CP-odd fraction in the decay B-0-->D*+D*- using a data sample of 88x10(6)B (B) over bar pairs collected by the BABAR detector at the PEP-II B Factory at SLAC. We determine the CP-odd fraction to be 0.063+/-0.055(stat)+/-0.009(syst). The time-dependent CP asymmetry parameters Im(lambda(+)) and \lambda(+)\ are determined to be 0.05+/-0.29(stat)+/-0.10(syst) and 0.75+/-0.19(stat)+/-0.02(syst), respectively. The standard model predicts these parameters to be -sin2beta and 1, respectively, in the absence of penguin diagram contributions

Measurement of the branching fraction and CP violating asymmetries in neutral B decays to D*+- D-+

We present measurements of the branching fraction and CP-violating asymmetries for neutral B decays to D*+-D-+. The measurement uses a data sample of approximately 88 million Y(4S) --> B Bbar decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. We measure the branching fraction to be (8.8 +- 1.0 +- 1.3) x 10^-4 and the time-integrated CP-violating asymmetry between the rates to D*+D- and D*-D+ to be A = -0.03 +- 0.11 +- 0.05. We also measure the time-dependent CP-violating asymmetry parameters to be S-+ = -0.24 +- 0.69 +- 0.12, C-+ = -0.22 +- 0.37 +- 0.10 for B --> D*-D+ and S+- = -0.82 +- 0.75 +- 0.14$, C+- = -0.47 +- 0.40 +- 0.12 for B --> D*+D-. In each case the first error is statistical and the second error is systematic.Comment: 7 pages, 3 figures, published as Phys. Rev. Lett 90 (2003) 22180

Measurement of the branching fraction for inclusive semileptonic B meson decays

A largely model-independent measurement of the inclusive electron momentum spectrum and branching fraction for semileptonic decays of B mesons is presented based on data recorded at the Upsilon(4S) resonance with the BABAR detector. Backgrounds from secondary charm decays are separated from prompt B decays using charge and angular correlations between the electron from one B meson and a high momentum electron tag from the second B meson. The resulting branching fraction is BR(B -> X e nu) = (10.87 +-0.18(stat)+-0.30(syst))%. Based on this measurement we determine the CKM matrix element |V_cb|