The formation of long-lived radicals in the solutions of casein and its hydrolysate with an equimolar mixture of amino acids was compared by measuring the X-ray-induced chemiluminescence. It was ...shown that free amino acids constituting the protein produce long-lived radicals. It was demonstrated that some amino acids (Leu, Ile, Val, Ser, Trp, Met, Pro, Arg, Gly, Phe) emit light of visible spectrum over a long period of time after the irradiation, which indicates the generation of long-lived radicals of these amino acids. The half-life times of these radicals are several hours. Dissolving irradiated dry amino acids capable of luminescing over a long time gives rise to the formation of hydrogen peroxide in aqueous medium.
A new knee-like approximation of the lateral distribution function (LDF) of EAS Cherenkov light in the 30–3000 TeV energy range was proposed and tested with simulated showers in our earlier studies. ...This approximation fits the LDFs of individual showers accurately for all types of primary particles gamma-rays, protons, and nuclei) and is suitable for reconstructing the shower core, determining the energy, and separating gamma-induced showers from hadron-induced ones. In the present study, the knee-like fitting function is used to determine the parameters of real showers detected by TAIGA-HiSCORE. It is demonstrated that this approximation characterizes properly all types of individual LDFs of experimental events in the 300–1000 TeV range. The accuracy of fit is governed by fluctuations intrinsic to the process of measurement of the Cherenkov photon density. The probability density function of these fluctuations was reconstructed and introduced into simulations. Certain useful methodical applications of the knee-like approximation are con-sidered, and the possibility of shower sorting into nuclei groups is examined. The extensive statistical coverage and detailed LDF measurement data of HiSCORE have provided the first opportunity to examine in depth the LDF of Cherenkov radiation in the 300–1000 TeV range.
The dark photon A' and the dark Higgs boson h' are hypothetical constituents featured in a number of recently proposed dark sector models. Assuming prompt decays of both dark particles, we search for ...their production in the so-called Higgstrahlung channel e+e- → A'h' , with h' → A'A' . We investigate ten exclusive final states with A' → e+e- , μ+μ- , or π+π- in the mass ranges 0.1GeV/c2<mA'< 3.5GeV/c2 and 0.2GeV/c2<mh'<10.5GeV/c2 . We also investigate three inclusive final states 2 ( e+e- ) X , 2 ( μ+μ- ) X , and ( e+e- ) ( μ+μ- ) X , where X denotes a dark photon candidate detected via missing mass, in the mass ranges 1.1GeV/c2<mA'<3.5GeV/c2 and 2.2GeV/c2<mh'<10.5GeV/c2 . Using the entire 977fb-1 data set collected by Belle, we determine no significant signal. Here, we obtain individual and combined 90% credibility level upper limits on the branching fraction times the Born cross section, B ×σBorn , on the Born cross section σBorn , and on the dark photon coupling to the dark Higgs boson times the kinetic mixing between the standard model photon and the dark photon, αD×ε2 . These limits improve upon and cover wider mass ranges than previous experiments. The limits from the final states 3 ( π+π- ) and 2 ( e+e- ) X are the first placed by any experiment. For αD equal to 1/137 , mh'<8GeV/c2 , and mA'<1GeV/c2 , we exclude values of the mixing parameter ε above ~ 8×10-4.
We search for CP violation in neutral charm meson decays using a data sample with an integrated luminosity of 966 fb–1 collected with the Belle detector at the KEKB e+e– asymmetric-energy collider. ...The asymmetry obtained in the rate of D0 and D0¯ decays to the π0π0 final state, –0.03±0.64(stat)±0.10(syst)%, is consistent with no CP violation. This constitutes an order of magnitude improvement over the existing result. Here, we also present an updated measurement of the CP asymmetry in the D0→K$^{0}_{S}$π0 decay: ACP(D0 → K$^{0}_{S}$π0) = –0.21±0.16(stat)±0.07(syst)%.
From April to July 2018, a data sample at the peak energy of the resonance was collected with the Belle II detector at the SuperKEKB electron-positron collider. This is the first data sample of the ...Belle II experiment. Using Bhabha and digamma events, we measure the integrated luminosity of the data sample to be ( , where the first uncertainty is statistical and the second is systematic. This work provides a basis for future luminosity measurements at Belle II.
We report a search for B decays to selected final states with the ηc meson: B± → K±ηcπ+π-, B± → K±ηcω, B± → K±ηcη and B± → K±ηcπ0. The analysis is based on 772 × 106 BB-bar pairs collected at the ...Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We set 90% confidence level upper limits on the branching fractions of the studied B decay modes, independent of intermediate resonances, in the range (0.6–5.3) × 10-4. We also search for molecular-state candidates in the D0D*-bar0 - D-bar0D*0, D0D-bar0 + D-bar0D0 and D*0D*-bar0 + D*-bar0D*0 combinations, neutral partners of the Z(3900)± and Z(4020)±, and a poorly understood state X(3915) as possible intermediate states in the decay chain, and set 90% confidence level upper limits on the product of branching fractions to the mentioned intermediate states and decay branching fractions of these states in the range (0.6–6.9) × 10-5.
The Belle II Physics Book Urquijo, P.; Bell, G.; Bigi, I. I. ...
Progress of theoretical and experimental physics,
12/2019, Letnik:
2019, Številka:
12
Journal Article
Recenzirano
Odprti dostop
We present the physics program of the Belle II experiment, located on the intensity frontier SuperKEKB e+e- collider. Belle II collected its first collisions in 2018, and is expected to operate for ...the next decade. It is anticipated to collect 50/ab of collision data over its lifetime. This book is the outcome of a joint effort of Belle II collaborators and theorists through the Belle II theory interface platform (B2TiP), an effort that commenced in 2014. The aim of B2TiP was to elucidate the potential impacts of the Belle II program, which includes a wide scope of physics topics: B physics, charm, tau, quarkonium, electroweak precision measurements and dark sector searches. It is composed of nine working groups (WGs), which are coordinated by teams of theorist and experimentalists conveners: Semileptonic and leptonic B decays, Radiative and Electroweak penguins, φ1 and φ2 (time-dependent CP violation) measurements, φ3 measurements, Charmless hadronic B decay, Charm, Quarkonium(like), tau and low-multiplicity processes, new physics and global fit analyses. This book highlights "golden- and silver-channels", i.e. those that would have the highest potential impact in the field. Theorists scrutinised the role of those measurements and estimated the respective theoretical uncertainties, achievable now as well as prospects for the future. Experimentalists investigated the expected improvements with the large dataset expected from Belle II, taking into account improved performance from the upgraded detector.
Using a sample of 158 x 10 super(6) Upsilon(2S) events collected with the Belle detector, we search for the first time for double-charmonium decays of the P-wave spin-triplet bottomonium states ...(Upsilon(2S) arrow right gamma chi bJ, arrow right J/psiJ/psipsi',psi 'psi' for J = 0, 1, and 2). No significant chi bJ signal is observed in the double-charmonium mass spectra, and we obtain the following upper limits: Bernoulli( chi bJ arrow right J/psiJ/psi) < 7.1 x 10 super(-5) 2.7 x 10 super(-5), 4.5 x 10 super(-5), Bernoulli( chi bJ arrow right J/psipsi) < 1.2 x 10 super(-4), 1.7 x 10 super(-5), 4.9 x 10 super(-5), Bernoulli( chi bJ arrow right psi'psi') < 3.1 x 10 super(-5), 6.2 x 10 super(-5), 1.6 x 10 super(-5) for J = 0, 1, and 2, respectively, at the 90% confidence level. These limits are significantly lower than the central values (with uncertainties of 50% to 70%) predicted using the light cone formalism but are consistent with calculations using the nonrelativistic QCD (NRQCD) factorization approach.
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