Korea Institute of Science and Technology Information

About: Korea Institute of Science and Technology Information is a facility organization based out in Daejeon, South Korea. It is known for research contribution in the topics: Gravitational wave & LIGO. The organization has 1152 authors who have published 2319 publications receiving 93849 citations. The organization is also known as: Korea Institute of Science and Technology Information & KISTI.

Effects of waveform model systematics on the interpretation of GW150914

Abstract: Parameter estimates of GW150914 were obtained using Bayesian inference, based on three semi-analytic waveform models for binary black hole coalescences. These waveform models differ from each other in their treatment of black hole spins, and all three models make some simplifying assumptions, notably to neglect sub-dominant waveform harmonic modes and orbital eccentricity. Furthermore, while the models are calibrated to agree with waveforms obtained by full numerical solutions of Einstein's equations, any such calibration is accurate only to some non-zero tolerance and is limited by the accuracy of the underlying phenomenology, availability, quality, and parameter-space coverage of numerical simulations. This paper complements the original analyses of GW150914 with an investigation of the effects of possible systematic errors in the waveform models on estimates of its source parameters. To test for systematic errors we repeat the original Bayesian analysis on mock signals from numerical simulations of a series of binary configurations with parameters similar to those found for GW150914. Overall, we find no evidence for a systematic bias relative to the statistical error of the original parameter recovery of GW150914 due to modeling approximations or modeling inaccuracies. However, parameter biases are found to occur for some configurations disfavored by the data of GW150914: for binaries inclined edge-on to the detector over a small range of choices of polarization angles, and also for eccentricities greater than ~0.05. For signals with higher signal-to-noise ratio than GW150914, or in other regions of the binary parameter space (lower masses, larger mass ratios, or higher spins), we expect that systematic errors in current waveform models may impact gravitational-wave measurements, making more accurate models desirable for future observations.

Evidence for direct CP violation in the decay B±→ D(*)K±, D→KS0π+π - and measurement of the CKM phase φ3

Abstract: We present a new measurement of the unitarity triangle angle phi(3) using a Dalitz plot analysis of the K-S(0)pi(+)pi(-) decay of the neutral D meson produced in B-+/- -> D-(*()) K-+/- decays. The method exploits the interference between D-0 and (D) over bar (0) to extract the angle phi(3), strong phase delta, and the ratio r of suppressed and allowed amplitudes. We apply this method to a 605 fb(-1) data sample collected by the Belle experiment. The analysis uses three decays: B-+/- -> DK +/-, and B-+/- -> D*K-+/- with D* -> D pi(0) and D* -> D gamma, as well as the corresponding charge-conjugate modes. From a combined maximum likelihood fit to the three modes, we obtain phi(3) = 78.4 degrees (+10.8 degrees)(-11.6 degrees) +/- 3.6 degrees (syst) +/- 8.9 degrees (model). CP conservation in this process is ruled out at the confidence level (1 - CL) = 5 X 10(-4), or 3.5 standard deviations.

Search for Subsolar-Mass Ultracompact Binaries in Advanced LIGO’s First Observing Run

Abstract: We present a search for subsolar mass ultracompact objects in data obtained during Advanced LIGO’s second observing run. In contrast to a previous search of Advanced LIGO data from the first observing run, this search includes the effects of component spin on the gravitational waveform. We identify no viable gravitational-wave candidates consistent with subsolar mass ultracompact binaries with at least one component between 0.2 M⊙–1.0 M⊙. We use the null result to constrain the binary merger rate of (0.2 M⊙, 0.2 M⊙) binaries to be less than 3.7×105 Gpc-3 yr-1 and the binary merger rate of (1.0 M⊙, 1.0 M⊙) binaries to be less than 5.2×103 Gpc-3 yr-1. Subsolar mass ultracompact objects are not expected to form via known stellar evolution channels, though it has been suggested that primordial density fluctuations or particle dark matter with cooling mechanisms and/or nuclear interactions could form black holes with subsolar masses. Assuming a particular primordial black hole (PBH) formation model, we constrain a population of merging 0.2 M⊙ black holes to account for less than 16% of the dark matter density and a population of merging 1.0 M⊙ black holes to account for less than 2% of the dark matter density. We discuss how constraints on the merger rate and dark matter fraction may be extended to arbitrary black hole population models that predict subsolar mass binaries.

Rigidity-Induced Delayed Fluorescence by Ortho Donor-Appended Triarylboron Compounds: Record-High Efficiency in Pure Blue Fluorescent Organic Light-Emitting Diodes

Abstract: A synthetic approach to highly efficient thermally activated delayed fluorescence (TADF) is proposed that uses ortho donor (D)–acceptor (A) compounds (PXZoB, DPAoB, and CzoB), wherein the acceptor is based on triarylboron and the donor is phenoxazine (PXZ), diphenylamine (DPA), or carbazole (Cz). Combined with the ortho D–A connectivity, the bulky nature of the triarylboron endows the D–A dyads with inherent steric “locking” for a highly twisted arrangement, leading to a small energy difference between singlet and triplet excited states (ΔEST) and thus exhibiting very efficient TADF with microsecond-range lifetimes. In sharp contrast, the corresponding para D–A derivatives, DPApB and CzpB, only display short-lived, normal fluorescence. Organic light-emitting diodes (OLEDs) incorporating the proposed ortho D–A compounds as emitters display orange, greenish-blue, and pure blue emission and exhibit high external quantum efficiency (ηEQE). In particular, the pure blue OLEDs based on the proposed ortho D–A emi...

Observation of B(+) -> (D)over-bar*(0)tau(+) v(tau) and evidence for B(+) -> (D)over-bar(0)tau(+) v(tau) at Belle

Abstract: We present measurements of B+ -> (D) over bar*(0)tau(+) v(tau) and B+ -> (D) over bar (0)tau(+) v(tau) decays in a data sample of 657 x 10(6) B (B) over bar pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We find 446(-56)(+58) B+ -> (D) over bar*(0)tau(+) v(tau) events with a significance of 8.1 standard deviations, and 146(-41)(+42) B+ -> (D) over bar (0)tau(+) v(tau) events with a significance of 3.5 standard deviations. The latter signal provides the first evidence for this decay mode. The measured branching fractions are B(B+ -> (D) over bar*(0)tau(+) v(tau)) = (2.12(-0.27)(+0.28) (stat) +/- 0.29(syst))% and B(B+ -> (D) over bar (0)tau(+) v(tau) ) = (0.77 +/- 0.22(stat) +/- 0.12(syst))%.