We report the results of a search for D0-D0 mixing in D0 --> K+ pi- decays based on 400 fb(-1) of data accumulated by the Belle detector at KEKB. Both assuming CP conservation and allowing for CP ...violation, we fit the decay-time distribution for the mixing parameters x and y, as well as for the parameter R(D), the ratio of doubly Cabibbo-suppressed decays to Cabibbo-favored decays. The 95% confidence level region in the (x'2,y') plane is obtained using a frequentist method. Assuming CP conservation, we find x'2 < 0.72 x 10(-3) and -9.9 x 10(-3) < y' < 6.8 x 10(-3) at the 95% confidence level; these are the most stringent constraints on the mixing parameters to date. The no-mixing point (0,0) has a confidence level of 3.9%. Assuming no mixing, we measure R(D) = (0.377 +/- 0.008 +/- 0.005)%.
Using a sample of \(1.31\times10^9\) \(J/\psi\) events collected with the BESIII detector at the electron-positron collider BEPCII, we analyse the full \(J/\psi \to\) \(\Xi^-\overline{\Xi}^+\), ...\(\Xi^-\to \Lambda \pi^-\), \(\Lambda\to p\pi^-\), \(\overline{\Xi}^+\to\overline{\Lambda}\pi^+\), \(\overline{\Lambda}\to\overline{p}\pi^+\) decay chain. A new method, exploiting the fact that the \(\Xi^-\overline{\Xi}^+\) pair is entangled and sequentially decaying, and where the complete decay chains are reconstructed, is applied for the first time. This enables precision measurements of the decay parameters for the \(\Xi^-\to\Lambda\pi^-\) decay (\(\alpha_{\Xi}\), \(\phi_{\Xi}\)) as well as the \(\overline{\Xi}^+\to\overline{\Lambda}\pi^+\) decay (\(\overline{\alpha}_{\Xi}\), \(\overline{\phi}_{\Xi}\)). From the decay parameters, two independent CP tests were performed, quantified by the observables \(A_{\rm CP}^{\Xi}\) and \(\Delta \phi_\Xi\). Our results, \(A_{\rm CP}^{\Xi}\) = \((6.0\pm13.4\pm5.6)\times10^{-3}\) and \(\Delta \phi_\Xi= (-4.8\pm13.7\pm2.9)\times10^{-3}~{\rm rad}\), are consistent with CP symmetry. Furthermore, our method enables a separation of strong and weak \(\Xi\to\Lambda\pi\) decay amplitudes. This results in the first direct measurement of the weak phase difference for any baryon decay. The result is found to be \((\xi_{P} - \xi_{S}) = (1.2\pm3.4\pm0.8)\times10^{-2}\) rad and is one of the most precise tests of CP symmetry for strange baryons. The strong phase difference is measured to be \((\delta_P - \delta_S) = (-4.0\pm3.3\pm1.7)\times10^{-2}\) rad. In addition, we provide an independent measurement of the recently debated \(\Lambda\) decay parameter, \(\alpha_{\Lambda} = 0.757 \pm 0.011 \pm 0.008 \). The \(\Lambda\overline{\Lambda}\) asymmetry is measured to be \(A_{\rm CP}^{\Lambda} = (-3.7\pm11.7\pm9.0)\times10^{-3}\).
The Born cross sections of the \(e^{+}e^{-}\to\Sigma^{+}\bar{\Sigma}^{-}\) and \(e^{+}e^{-}\to\Sigma^{-}\bar{\Sigma}^{+}\) processes are determined with high precision for center-of-mass energy from ...2.3864 to 3.0200 GeV with the BESIII detector. Nonzero cross sections near threshold are observed. The resulting ratio of effective form factors for the \(\Sigma^{+}\) and \(\Sigma^{-}\) is consistent with 3, agreeing with the ratio of the incoherent sum of the squared charges of the \(\Sigma^{+}\) and \(\Sigma^{-}\) valence quarks, but disagreeing with various theoretical predictions. In addition, ratios of the \(\Sigma^{+}\) electric and magnetic form factors, \(|G_{E}/G_{M}|\), are obtained at three center-of-mass energies through an analysis of the angular distributions. These measurements, which are studied for the first time in the off-resonance region, provide precision experimental input for understanding baryonic structure. The observed novel features of the \(\Sigma^{\pm}\) form factors require a new theoretical description for the hyperons.
Sample preparation for high-throughput sequencing (HTS) includes treatment with various laboratory components, potentially carrying viral nucleic acids, the extent of which has not been thoroughly ...investigated. Our aim was to systematically examine a diverse repertoire of laboratory components used to prepare samples for HTS in order to identify contaminating viral sequences.
A total of 322 samples of mainly human origin were analysed using eight protocols, applying a wide variety of laboratory components. Several samples (60% of human specimens) were processed using different protocols. In total, 712 sequencing libraries were investigated for viral sequence contamination.
Among sequences showing similarity to viruses, 493 were significantly associated with the use of laboratory components. Each of these viral sequences had sporadic appearance, only being identified in a subset of the samples treated with the linked laboratory component, and some were not identified in the non-template control samples. Remarkably, more than 65% of all viral sequences identified were within viral clusters linked to the use of laboratory components.
We show that high prevalence of contaminating viral sequences can be expected in HTS-based virome data and provide an extensive list of novel contaminating viral sequences that can be used for evaluation of viral findings in future virome and metagenome studies. Moreover, we show that detection can be problematic due to stochastic appearance and limited non-template controls. Although the exact origin of these viral sequences requires further research, our results support laboratory-component-linked viral sequence contamination of both biological and synthetic origin.
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Using 281 fb-1 of data from the Belle experiment recorded at or near the (4S) resonance, we have measured the rates of the "wrong-sign" decays D0 --> K+ pi- pi0 and D0 --> K+ pi- pi+ pi- relative to ...those of the Cabibbo-favored decays D0 --> K- pi+ pi0 and D0 --> K- pi+ pi+ pi-. These wrong-sign decays proceed via a doubly Cabibbo-suppressed amplitude or via D0-D0 mixing; the latter has not yet been observed. We obtain R(WS)(K pi pi0) = 0.229 +/- 0.015(stat)(+0.013)(-0.009)(syst)% and R(WS)(K3pi) = 0.320 +/- 0.018(stat)(+0.018)(0.013)(syst)%. The CP asymmetries are measured to be -0.006 +/- 0.053 and -0.018 +/- 0.044 for the K+ pi- pi0 and K+ pi- pi+ pi- final states, respectively.
We study average Hewitt–Stromberg measures of typical compact metric spaces belonging to the Gromov–Hausdorff space (of all compact metric spaces) equipped with the Gromov–Hausdorff metric.
Here we present new results for the Born cross section and the effective form factor of the neutron at the center-of-mass energies \({\bf \sqrt{s}}\) between 2.0 and 3.08 GeV, using 18 data sets ...corresponding to an integrated luminosity of 647.9 pb\({\bf ^{-1}}\) from e\({\bf ^+}\)e\({\bf ^-}\) annihilation reactions collected at the BESIII experiment. The process \(e^{+}e^{-}\to n\bar{n}\) is analyzed with three individual categories to improve the efficiency of \(n\bar{n}\) reconstruction. The cross section of \(e^{+}e^{-}\to n\bar{n}\) is measured at 18 c.m. energies where the best precision is 8.1\% at \(\sqrt{s}=2.396\) GeV. The corresponding effective form factors are extracted under the assumption \(|G_{E}|=|G_{M}|\). Our results improve the statistical precision on the neutron form factor by more than a factor of 60 over previous measurements from the FENICE and DM2 experiments and usher in a new era where neutron form factor data from annihilation in the time-like regime is on par with that from electron scattering experiments. In addition, an oscillatory behavior of the effective form factor observed for the proton is discussed for the neutron.
New limits are presented on the cross section for Weakly Interacting Massive Particle (WIMP) nucleon scattering in the KIMS CsI(T) detector array at the Yangyang Underground Laboratory. The exposure ...used for these results is 24524.3 kg\cdotdays. Nuclei recoiling from WIMP interactions are identified by a pulse shape discrimination method. A low energy background due to alpha emitters on the crystal surfaces is identified and taken into account in the analysis. The detected numbers of nuclear recoils are consistent with zero and 90% confidence level upper limits on the WIMP interaction rates are set for electron equivalent energies from 3 keV to 11 keV. The 90% upper limit of NR event rate for 3.6-5.8 keV corresponding to 2-4 keV in NaI(T) is 0.0098 counts/kg/keV/day which is below the annual modulation amplitude reported by DAMA. This is incompatible with interpretations that enhance the modulation amplitude such as inelastic dark matter models. We establish the most stringent cross section limits on spin-dependent WIMP-proton elastic scattering for the WIMP masses greater than 20 GeV/c2.
Thick fine-grained, nonuniformly stratified deposits along a 20 km stretch coastline have been investigated using a combined marine and terrestrial approach. The sediments were deposited rapidly in ...glaciomarine, marine and submarine ice-contact environments during the Allerød and Younger Dryas periods. Rapid glacioisostatic rebound caused extensive modification of the landscape, mainly by sliding. Slides in the area were affected by the bedrock morphology, location and sedimentation rate of the glaciomarine sediments, isostatic rebound, presence of gas/fluids in marine sediments and later, river incision, tides and groundwater flow. Spatial and temporal distribution of slide deposits in the marine stratigraphy, and morphology of submarine and terrestrial features give detailed information of landscape evolution through time. This is illustrated by conceptual profiles from three areas that explain the landscape evolution and changing processes during the rebound. The most intensive slide activity, both in frequencies and volumes, and hence the most considerable landscape modification occurred early in the Holocene period i.e. when the relative sea level fell most rapidly.
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