Measurements of time-dependent CP asymmetries in B→D∗∓π±B \to D^{*\mp} \pi^{\pm} decays using a partial reconstruction technique

We report results on time-dependent CP asymmetries in $B \to D^{*\mp}\pi^{\pm}$ decays based on a data sample containing 657 {\times} $10^6$ $B\bar{B}$ pairs collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider at the $\Upsilon(4S)$ resonance. We use a partial reconstruction technique, wherein signal $B \to D^{*\mp}\pi^{\pm}$ events are identified using information only from the fast pion from the B decay and the slow pion from the subsequent decay of the $D^{*\mp}$, where the former (latter) corresponds to $D^{*+} (D^{*-})$ final states. We obtain CP violation parameters $S^+ = +0.061 \pm 0.018(\mathrm{stat}) \pm 0.012(\mathrm{syst})$ and $S^- = +0.031 \pm 0.019(\mathrm{stat}) \pm 0.015(\mathrm{syst})$.Comment: 8 pages, 5 figures, 2 tables, submitted to Physical Review D (RC

Evidence for a new resonance and search for the Y(4140) in γγ→ϕJ/ψ\gamma \gamma \to \phi J/\psi

The process \gamma \gamma \to \phi \jpsi is measured for \phi \jpsi masses between threshold and 5 GeV/${\it c}^2$, using a data sample of 825 fb$^{-1}$ collected with the Belle detector. A narrow peak of $8.8^{+4.2}_{-3.2}$ events, with a significance of 3.2 standard deviations including systematic uncertainty, is observed. The mass and natural width of the structure (named X(4350)) are measured to be $(4350.6^{+4.6}_{-5.1}(\rm{stat})\pm 0.7(\rm{syst})) \hbox{MeV}/{\it c}^2$ and $(13^{+18}_{-9}(\rm{stat})\pm 4(\rm{syst})) \hbox{MeV}$, respectively. The product of its two-photon decay width and branching fraction to \phi\jpsi is $(6.7^{+3.2}_{-2.4}(\rm{stat}) \pm 1.1(\rm{syst})) \hbox{eV}$ for $J^P=0^+$, or $(1.5^{+0.7}_{-0.6}(\rm{stat}) \pm 0.3(\rm{syst})) \hbox{eV}$ for $J^P=2^+$. No signal for the Y(4140)\to \phi \jpsi structure reported by the CDF Collaboration in B\to K^+ \phi \jpsi decays is observed, and limits of \Gamma_{\gamma \gamma}(Y(4140)) \BR(Y(4140)\to\phi \jpsi)<41 \hbox{eV} for $J^P=0^+$ or $<6.0 \hbox{eV}$ for $J^P=2^+$ are determined at the 90% C.L. This disfavors the scenario in which the Y(4140) is a $D_{s}^{\ast+} {D}_{s}^{\ast-}$ molecule.Comment: 9 pages, 3 figures, publication in Phys. Rev. Lett. 104, 112004, 201

Use of automatic radiosonde launchers to measure temperature and humidity profiles from the GRUAN perspective

In the last two decades, technological progress has not only seen improvements to the quality of atmospheric upper-air observations but also provided the opportunity to design and implement automated systems able to replace measurement procedures typically performed manually. Radiosoundings, which remain one of the primary data sources for weather and climate applications, are still largely performed around the world manually, although increasingly fully automated upper-air observations are used, from urban areas to the remotest locations, which minimize operating costs and challenges in performing radiosounding launches. This analysis presents a first step to demonstrating the reliability of the automatic radiosonde launchers (ARLs) provided by Vaisala, Meteomodem and Meisei. The metadata and datasets collected by a few existing ARLs operated by the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) certified or candidate sites (Sodankylä, Payerne, Trappes, Potenza) have been investigated and a comparative analysis of the technical performance (i.e. manual versus ARL) is reported. The performance of ARLs is evaluated as being similar or superior to those achieved with the traditional manual launches in terms of percentage of successful launches, balloon burst and ascent speed. For both temperature and relative humidity, the ground-check comparisons showed a negative bias of a few tenths of a degree and % RH, respectively. Two datasets of parallel soundings between manual and ARL-based measurements, using identical sonde models, provided by Sodankylä and Faa'a stations, showed mean differences between the ARL and manual launches smaller than ±0.2 K up to 10 hPa for the temperature profiles. For relative humidity, differences were smaller than 1 % RH for the Sodankylä dataset up to 300 hPa, while they were smaller than 0.7 % RH for Faa'a station. Finally, the observation-minus-background (O–B) mean and root mean square (rms) statistics for German RS92 and RS41 stations, which operate a mix of manual and ARL launch protocols, calculated using the European Centre for Medium-Range Weather Forecasts (ECMWF) forecast model, are very similar, although RS41 shows larger rms(O–B) differences for ARL stations, in particular for temperature and wind. A discussion of the potential next steps proposed by GRUAN community and other parties is provided, with the aim to lay the basis for the elaboration of a strategy to fully demonstrate the value of ARLs and guarantee that the provided products are traceable and suitable for the creation of GRUAN data products

First Measurement of Inclusive B -> X_s eta Decays

We report a first measurement of inclusive B -> X_s eta decays, where X_s is a charmless state with unit strangeness. The measurement is based on a pseudo-inclusive reconstruction technique and uses a sample of 657 x 10^6 BB-bar pairs accumulated with the Belle detector at the KEKB e^+e^- collider. For M_{X_s} < 2.6 GeV/c^2, we measure a branching fraction of (26.1 +/- 3.0 (stat) +1.9 -2.1 (syst) +4.0 -7.1 (model)) x 10^-5 and a direct CP asymmetry of A_{CP} = -0.13 +/- 0.04 +0.02 -0.03. Over half of the signal occurs in the range M_{X_s} > 1.8 GeV/c^2.Comment: 6 pages, 1 figure, 1 table, submitted to Physical Review Letter

First study of \eta_c, \eta(1760) and X(1835) production via \eta'\pi^+\pi^- final states in two-photon collisions

The invariant mass spectrum of the \eta' \pi^+ \pi^- final state produced in two-photon collisions is obtained using a 673 fb^{-1} data sample collected in the vicinity of the \Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. We observe a clear signal of the \eta_c and measure its mass and width to be M(\eta_c)=(2982.7 +- 1.8(stat) +- 2.2(syst) +- 0.3(model)) MeV/c^2 and \Gamma(\eta_c) = (37.8^{+5.8}_{-5.3}(stat) +- 2.8(syst) +- 1.4(model)) MeV/c^2. The third error is an uncertainty due to possible interference between the \eta_c and a non-resonant component. We also report the first evidence for \eta(1760) decay to \eta' \pi^+ \pi^-; we find two solutions for its parameters, depending on the inclusion or not of the X(1835), whose existence is of marginal significance in our data. From a fit to the mass spectrum using coherent X(1835) and \eta(1760) resonant amplitudes, we set a 90% confidence level upper limit on the product \Gamma_{\gamma\gamma} \BR (\eta' \pi^+ \pi^-) for the X(1835).Comment: 13 pages, 7 figures, submitted to PR

Search for CP violation in tau -> K^0_S pi nu_tau decays at Belle

We report on a search for CP violation in tau -> K^0_S pi nu_tau decays using a data sample of 699 fb^{-1} collected in the Belle experiment at the KEKB electron-positron asymmetric-energy collider. The CP asymmetry is measured in four bins of the invariant mass of the K^0_S pi system and found to be compatible with zero with a precision of O(10^{-3}) in each mass bin. Limits for the CP violation parameter Im(eta_S) are given at a 90 % confidence level. These limits are |Im(eta_S)|<0.026 or better, depending on the parameterization used to describe the hadronic form factors and improve upon previous limits by one order of magnitude

Search for leptonic decays of D0 mesons

We search for the flavor-changing neutral current decays D0\to mu+mu- and D0\to e+e-, and for the lepton-flavor violating decays D0\to e\pm mu\mp using 660 fb^-1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. We find no evidence for any of these decays. We obtain significantly improved upper limits on the branching fractions: B(D0\to mu+mu-)<1.4x10-7, B(D0\to e+e-)<7.9x10-8, and B(D0\to e+mu-)+B(D0\to mu+e-)<2.6x10-7 at 90% confidence level.Comment: 6 pages, 3 figure

Search for CP Violation in the Decays D0→KS0P0D^0\rightarrow K^0_S P^0

We have searched for CP violation in the decays $D^0\rightarrow K^0_S P^0$ where $P^0$ denotes a neutral pseudo-scalar meson which is either a $\pi^0$, $\eta$, or $\eta'$ using KEKB asymmetric-energy $e^+e^-$ collision data corresponding to an integrated luminosity of 791 fb$^{-1}$ collected with the Belle detector. No evidence of significant CP violation is observed. We report the most precise CP asymmetry measurement in the decay $D^0\rightarrow K^0_S\pi^0$ to date: $A_{CP}^{D^0\rightarrow K^0_S\pi^0}=(-0.28\pm0.19\pm0.10)$. We also report the first measurements of CP asymmetries in the decays $D^0\rightarrow K^0_S\eta$ and $D^0\rightarrow K^0_S\eta'$: $A_{CP}^{D^0\rightarrow K^0_S\eta}=(+0.54\pm0.51\pm0.16)$ and $A_{CP}^{D^0\rightarrow K^0_S\eta'}=(+0.98\pm0.67\pm0.14)$, respectively

Search for CP Violation in D Meson Decays to phi pi+

We search for CP violation in Cabibbo-suppressed charged D meson decays by measuring the difference between the CP violating asymmetries for the Cabibbo-suppressed decays D+ -> K+K-pi+ and the Cabibbo-favored decays Ds -> K+K-pi+ in the K+K- mass region of the phi resonance. Using 955/fb of data collected with the Belle detector we obtain A_CP(D+ -> phi pi+) = (+0.51 +- 0.28 +- 0.05)%. The measurement improves the sensitivity of previous searches by more than a factor of five. We find no evidence for direct CP violation.Comment: submitted to PR