How to see an antistar
Abstract: ... click to read ...Polarization of photons emitted in weak decays occuring at distant star allows to determine whether this star is made from antimatter. Even more promissing is the observation of neutrinos (antineutrinos) produced at neutronization (antineutronization) reactions at the beginning of SN (SNbar) explosion.
A cosmological bound on e+e- mass difference
Abstract: ... click to read ...We demonstrate that CPT-violation due to image mass difference generates a non-zero photon mass. As a result the cosmological bounds on the photon mass lead to the bounds on image mass difference which are at least by 10 orders of magnitude stronger than the direct experimental bound.
Критический заряд в сверхсильном магнитном поле
Abstract: ... click to read ...Явление критического заряда в сверхсильных магнитных полях рассмотрено с учетом экранирования кулоновского потенциала и конечного размера ядра.
Search for doubly charmed baryons and study of charmed strange baryons at Belle
Abstract: ... click to read ...We report results of a study of doubly charmed baryons and charmed strange baryons. The analysis is performed using a 980 fb−1 data sample collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. We search for doubly charmed baryons Ξ+(+)cc with the Λ+cK−π+(π+) and Ξ0cπ+(π+) final states. No significant signal is observed. We also search for two excited charmed strange baryons, Ξc(3055)+ and Ξc(3123)+ with the Σ++c(2455)K− and Σ++c(2520)K− final states. The Ξc(3055)+ signal is observed with a significance of 6.6 standard deviations including systematic uncertainty, while no signature of the Ξc(3123)+ is seen. We also study properties of the Ξc(2645)+ and measure a width of 2.6±0.2(stat)±0.4(syst) MeV/c2, which is the first significant determination.
Study of B0->rho0rho0 decays, implications for the CKM angle phi_2 and search for other B0 decay modes with a four-pion final state
Abstract: ... click to read ...We present a study of the branching fraction of the decay B0→ρ0ρ0 and the fraction of longitudinally polarized ρ0 mesons in this decay. The results are obtained from the final data sample containing 772×106 BB¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We find 166±59 B0→ρ0ρ0 events (including systematic uncertainties), corresponding to a branching fraction of B(B0→ρ0ρ0)=(1.02±0.30(stat)±0.15(syst))×10−6 with a significance of 3.4 standard deviations and a longitudinal polarization fraction fL=0.21+0.18−0.22(stat)±0.15(syst). We use the longitudinal polarization fraction to determine the Cabibbo-Kobayashi-Maskawa matrix angle ϕ2=(84.9±13.5)° through an isospin analysis in the B→ρρ system. We furthermore find 125±41 B0→f0ρ0 events, corresponding to B(B0→f0ρ0)×B(f0→π+π−)=(0.78±0.22(stat)±0.11(syst))×10−6, with a significance of 3.1 standard deviations. We find no other significant contribution with the same final state, and set upper limits at 90% confidence level on the (product) branching fractions, B(B0→π+π−π+π−)<11.2×10−6, B(B0→ρ0π+π−)<12.0×10−6, B(B0→f0π+π−)×B(f0→π+π−)<3.0×10−6 and B(B0→f0f0)×B(f0→π+π−)2<0.2×10−6.
Search for B0 → pΛπ-γ at Belle
Abstract: ... click to read ...We search for the charmless B0 decay with final state particles pΛ¯π−γ using the full data sample that contains 772×106BB¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. This decay is predicted to proceed predominantly via the b→sγ radiative penguin process with a high energy photon. No significant signal is found. We set an upper limit of 6.5×10−7 for the branching fraction of B0→pΛ¯π−γ at the 90% confidence level.
Search for CP violation in D0 → π0π0 decays
Abstract: ... click to read ...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 D¯0 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. We also present an updated measurement of the CP asymmetry in the D0→K0Sπ0 decay: ACP(D0→K0Sπ0)=[−0.21±0.16(stat)±0.07(syst)]%.
Measurement of D0-D0 Mixing and Search for Indirect CP Violation Using D0→KS0π+π- Decays
Abstract: ... click to read ...We report a measurement of D0−D¯0 mixing parameters and a search for indirect CP violation through a time-dependent amplitude analysis of D0→K0Sπ+π− decays. The results are based on 921 fb−1 of data accumulated with the Belle detector at the KEKB asymmetric-energy e+e− collider. Assuming CP conservation, we measure the mixing parameters x=(0.56±0.19+0.03+0.06−0.09−0.09)% and y=(0.30±0.15+0.04+0.03−0.05−0.06)%, where the errors are statistical, experimental systematic, and systematic due to the amplitude model, respectively. With CP violation allowed, the parameters |q/p|=0.90+0.16+0.05+0.06−0.15−0.04−0.05 and arg(q/p)=(−6±11±3+3−4)° are found to be consistent with conservation of CP symmetry in mixing and in the interference between mixing and decay, respectively.
Measurements of the masses and widths of the Σc(2455)0/++ and Σc(2520)0/++ baryons
Abstract: ... click to read ...We present measurements of the masses and decay widths of the baryonic states Σc(2455)0/++ and Σc(2520)0/++ using a data sample corresponding to an integrated luminosity of 711 fb−1 collected with the Belle detector at the KEKB e+e− asymmetric-energy collider operating at the Υ(4S) resonance. We report the mass differences with respect to the Λ+c baryon M(Σc(2455)0)−M(Λ+c)=167.29±0.01±0.02 MeV/c2,M(Σc(2455)++)−M(Λ+c)=167.51±0.01±0.02 MeV/c2,M(Σc(2520)0)−M(Λ+c)=231.98±0.11±0.04 MeV/c2,M(Σc(2520)++)−M(Λ+c)=231.99±0.10±0.02 MeV/c2, and the decay widths Γ(Σc(2455)0)=1.76±0.04+0.09−0.21 MeV/c2,Γ(Σc(2455)++)=1.84±0.04+0.07−0.20 MeV/c2,Γ(Σc(2520)0)=15.41±0.41+0.20−0.32 MeV/c2,Γ(Σc(2520)++)=14.77±0.25+0.18−0.30 MeV/c2, where the first uncertainties are statistical and the second are systematic. The isospin mass splittings are measured to be M(Σc(2455)++)−M(Σc(2455)0)=0.22±0.01±0.01 MeV/c2 and M(Σc(2520)++)−M(Σc(2520)0)=0.01±0.15±0.03 MeV/c2.
Measurements of Branching Fractions of tau Lepton Decays with one or more K0s
Abstract: ... click to read ...We report measurements of branching fractions of τ lepton decays to final states with a K0S meson using a 669 fb−1 data sample accumulated with the Belle detector at the KEKB asymmetric-energy e+e− collider. The inclusive branching fraction is measured to be B(τ−→K0SX−ντ)=(9.15±0.01±0.15)×10−3, where X− can be anything; the exclusive branching fractions are B(τ−→π−K0Sντ)=(4.16±0.01±0.08)×10−3, B(τ−→K−K0Sντ)=(7.40±0.07±0.27)×10−4, B(τ−→π−K0Sπ0ντ)=(1.93±0.02±0.07)×10−3, B(τ−→K−K0Sπ0ντ)=(7.48±0.10±0.37)×10−4, B(τ−→π−K0SK0Sντ)=(2.33±0.03±0.09)×10−4, B(τ−→π−K0SK0Sπ0ντ)=(2.00±0.22±0.20)×10−5, where the first uncertainty is statistical and the second is systematic. For each mode, the accuracy is improved over that of pre-B-factory measurements by a factor ranging from five to ten. In τ−→π−K0SK0Sπ0ντ decays, clear signals for the intermediate states τ−→π−f1(1285)ντ and τ−→K*−K0Sπ0ντ are observed.