Improved search for D^0 mixing using semileptonic decays at Belle

A search for mixing in the neutral D meson system has been performed using semileptonic D0 -> K(*)- e+ \nu and D0 -> K(*)- \mu+ \nu decays. Neutral D mesons from D*+ -> D0 \pi_s^+ decays are used and the flavor at production is tagged by the charge of the slow pion. The measurement is performed using 492 fb^-1 of data recorded by the Belle detector. From the yield of right-sign and wrong-sign decays arising from non-mixed and mixed events, respectively, we measure the ratio of the time-integrated mixing rate to the unmixed rate to be R_M = (1.3 +- 2.2 +- 2.0) x 10^-4. This corresponds to an upper limit of R_M < 6.1 x 10^-4 at the 90% C.L.Comment: 20 pages, 16 figures, 8 tables; accepted by PRD; changes from previous version: minor rewording

Observation of B^0 \to D^{*-} \tau^+ \nu_{\tau} decay at Belle

We report an observation of the decay $B^0\to D^{*-} \tau^+ \nu_{\tau}$ in a data sample containing $535\times10^6$ $B\bar{B}$ pairs collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We find a signal with a significance of 5.2 standard deviations and measure the branching fraction $\mathcal{B}(B^0\to D^{*-} \tau ^+ \nu_{\tau})=(2.02 ^{+0.40}_{-0.37} (stat) \pm 0.37 (syst))$. This is the first observation of an exclusive $B$ decay with a $b \to c \tau \nu_{\tau}$ transition.Comment: 6 pages, 3 figures, submitted to Phys. Rev. Let

Measurements of time-dependent CP violation in B^0 -> psi(2S) K_S decays

We report improved measurements of time-dependent CP violation parameters for B^0(\bar{B}^0) -> psi(2S) K_S. This analysis is based on a data sample of 657x10^6 BBbar pairs collected at the Y(4S) resonance with the Belle detector at the KEKB energy-asymmetric e+e- collider. We fully reconstruct one neutral B meson in the psi(2S) K_S CP-eigenstate decay channel, and the flavor of the accompanying B meson is identified to be either B^0 or \bar{B}^0 from its decay products. CP violation parameters are obtained from the asymmetries in the distributions of the proper-time intervals between the two B decays: S (psi(2S) K_S) = +0.72 +/- 0.09(stat) +/- 0.03(syst), A (psi(2S) K_S) = +0.04 +/- 0.07(stat) +/- 0.05(syst). These results are in agreement with results from measurements of B^0 -> J/psi K^0.Comment: 6 pages, 4 figures, presented at 2007 Lepton-Photon Symposium (BELLE-CONF-0770). Modified version published in PRD(RC

Shower development of particles with momenta from 15 GeV to 150 GeV in the CALICE scintillator-tungsten hadronic calorimeter

We present a study of showers initiated by electrons, pions, kaons, and protons with momenta from 15 GeV to 150 GeV in the highly granular CALICE scintillator-tungsten analogue hadronic calorimeter. The data were recorded at the CERN Super Proton Synchrotron in 2011. The analysis includes measurements of the calorimeter response to each particle type as well as measurements of the energy resolution and studies of the longitudinal and radial shower development for selected particles. The results are compared to Geant4 simulations (version 9.6.p02). In the study of the energy resolution we include previously published data with beam momenta from 1 GeV to 10 GeV recorded at the CERN Proton Synchrotron in 2010.Comment: 35 pages, 21 figures, 8 table

Development of Advanced Photon Calibrator for KAGRA

The KAGRA cryogenic gravitational-wave observatory has begun joint observation with the worldwide gravitational waves detector network. Precise calibration of the detector response is essential for the parameter estimation of gravitational wave sources. The photon calibrator is the main calibrator in LIGO, Virgo and KAGRA, and we used this calibrator in joint observation 3 on 2020 April with GEO600 in Germany. KAGRA improved the system for joint observation 3 with three unique points: high laser power, power stabilization system, and remote beam position control. KAGRA employs the 20 W laser and divides it into two beams injected on the mirror surface. By using a high-power laser, we can calibrate the response at the kHz region. To control the power of each laser independently, we also installed an optical follower servo for each beam power stabilization. By controlling the optical path of the photon calibrater beam positions with pico-motors, we were able to characterize the rotation response of the detector. We also installed a telephoto camera and QPD to monitor beam position and controlled beam position to optimize mirror response. In this paper, we discussed the statistical error with the result of the relative power noise measurement. We also discussed systematic errors about the power calibration model of photon calibrator and simulation of elastic deformation effect with the finite element analysis.Comment: 16 pages, 10 figure

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

Measurement of the ratio B(D0->pi+pi-pi0)/B(D0->K-pi+pi0) and the time-integrated CP asymmetry in D0->pi+pi-pi0

We report a high-statistics measurement of the relative branching fraction B(D0->pi+pi-pi0)/B(D0->K-pi+pi0) using a 532 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The measured value of the relative branching fraction is B(D0->pi+pi-pi0)/B(D0->K-pi+pi0) = (10.12 +/- 0.04(stat) +/- 0.18(syst))x10^{-2} which has an accuracy comparable to the world average. We also present a measurement of the time-integrated CP asymmetry in D0->pi+pi-pi0 decay. The result, A_{CP} = (0.43 +/- 1.30)%, shows no significant CP violation.Comment: 15 pages, 11 figures, submitted to Physics Letters

Protection from Experimental Cerebral Malaria with a Single Dose of Radiation-Attenuated, Blood-Stage Plasmodium berghei Parasites

BACKGROUND: Whole malaria parasites are highly effective in inducing immunity against malaria. Due to the limited success of subunit based vaccines in clinical studies, there has been a renewed interest in whole parasite-based malaria vaccines. Apart from attenuated sporozoites, there have also been efforts to use live asexual stage parasites as vaccine immunogens. METHODOLOGY AND RESULTS: We used radiation exposure to attenuate the highly virulent asexual blood stages of the murine malaria parasite P. berghei to a non-replicable, avirulent form. We tested the ability of the attenuated blood stage parasites to induce immunity to parasitemia and the symptoms of severe malaria disease. Depending on the mouse genetic background, a single high dose immunization without adjuvant protected mice from parasitemia and severe disease (CD1 mice) or from experimental cerebral malaria (ECM) (C57BL/6 mice). A low dose immunization did not protect against parasitemia or severe disease in either model after one or two immunizations. The protection from ECM was associated with a parasite specific antibody response and also with a lower level of splenic parasite-specific IFN-γ production, which is a mediator of ECM pathology in C57BL/6 mice. Surprisingly, there was no difference in the sequestration of CD8+ T cells and CD45+ CD11b+ macrophages in the brains of immunized, ECM-protected mice. CONCLUSIONS: This report further demonstrates the effectiveness of a whole parasite blood-stage vaccine in inducing immunity to malaria and explicitly demonstrates its effectiveness against ECM, the most pathogenic consequence of malaria infection. This experimental model will be important to explore the formulation of whole parasite blood-stage vaccines against malaria and to investigate the immune mechanisms that mediate protection against parasitemia and cerebral malaria