Measurement of the matrix element for the decay η′ → ηπ 0 π 0 with the GAMS-4π spectrometer

The parameters of the Dalitz diagram for the decay η′ → ηπ ⁰ π ⁰ in a generalized and a linear representation were determined by using a statistical sample of 15 × 10³ events. A charge-exchange reaction at a momentum of 32 GeV/c was a source of monoenergetic η′ mesons. The experiment was performed with the aid of the GAMS-4π spectrometer.     

Precise measurement of the CP violation parameter sin2φ1 in B0→(cc¯)K0 decays

We present a precise measurement of the CP violation parameter sin2φ1 and the direct CP violation parameter A(f) using the final data sample of 772×10(6) BB[over ˉ] pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. One neutral B meson is reconstructed in a J/ψK(S)(0), ψ(2S)K(S)(0), χ(c1)K(S)(0), or J/ψK(L)(0) CP eigenstate and its flavor is identified from the decay products of the accompanying B meson. From the distribution of proper-time intervals between the two B decays, we obtain the following CP violation parameters: sin2φ1=0.667±0.023(stat)±0.012(syst) and A(f)=0.006±0.016(stat)±0.012(syst).     

Search for CP violation in the decays D(0)→K(S)(0)P(0)

We have searched for CP violation in the decays D(0)→K(S)(0)P(0) where P(0) denotes a neutral pseudoscalar meson that is either a π(0), η, or η' 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)→K(S)(0)π(0) to date: A(CP)(D(0)→K(S)(0)π(0))=(-0.28±0.19±0.10)%. We also report the first measurements of CP asymmetries in the decays D(0)→K(S)(0)η and D(0)→K(S)(0)η': A(CP)(D(0)→K(S)(0)η)=(+0.54±0.51±0.16)% and A(CP)(D(0)→K(S)(0)η')=(+0.98±0.67±0.14)%, respectively.     

Measurement of polarization and search for CP violation in B(s)0→φφ decays

We present the first measurement of polarization and CP-violating asymmetries in a B(s)(0) decay into two light vector mesons, B(s)(0)→φφ, and an improved determination of its branching ratio using 295 decays reconstructed in a data sample corresponding to 2.9 fb(-1) of integrated luminosity collected by the CDF experiment at the Fermilab Tevatron collider. The fraction of longitudinal polarization is determined to be f(L)=0.348±0.041(stat)±0.021(syst), and the branching ratio B(B(s)(0)→φφ)=[2.32±0.18(stat)±0.82(syst)]×10(-5). Asymmetries of decay angle distributions sensitive to CP violation are measured to be A(u)=-0.007±0.064(stat)±0.018(syst) and A(v)=-0.120±0.064(stat)±0.016(syst).     

OnΛ-hyperon(s) in the nuclear medium

Relativistic mean field theory is tested in reproducing the novel experimentalΛ single particle (π⁺, K⁺) spectra of Λ=12/90 hypernuclei (and extended to _Λ ²⁰⁹ Pb). The adjusted model is then applied to multistrange systems \({}_{n_\Lambda \Lambda }^{16 + n_\Lambda } O,_{n_\Lambda \Lambda }^{40 + n_\Lambda } Ca\) ; no anomalous behaviour of radii and densities in those multi-Λ hypernuclei is encountered.     

Polarization properties of baryons in the hadronic decays of the Δ(1232) resonance

The angular distribution of the probability for the Δ(1232)-resonance decay Δ(1232) → Nπ versus the polarizations of baryons and the vector of dynamical nucleon polarization are calculated.     

Measurement of the B(s)0 lifetime in fully and partially reconstructed B(s)0→D(s)(-)(ϕπ(-))X decays in p¯p collisions at √s=1.96 TeV

We present a measurement of the B(s)(0) lifetime in fully and partially reconstructed B(s)(0)→D(s)(-)(?π(-))X decays in 1.3 fb(-1) collected in pp ˉ collisions at √s=1.96 TeV by the CDF II detector at the Fermilab Tevatron. We measure τ(B(s)(0))=1.518±0.041(stat)±0.027(syst) ps. The ratio of this result and the world average B(0) lifetime yields τ(B(s)(0))/τ(B(0))=0.99±0.03, which is in agreement with recent theoretical predictions.     

Long-distance dominance of the CP asymmetry in B→X(s,d)γ decays

We show that in the standard model the parametrically leading (by a factor 1/α(s)) contribution to the inclusive CP asymmetry in B→X(s,d)γ decays arises from a long-distance effect in the interference of the electromagnetic dipole amplitude with the amplitude for an up-quark penguin transition accompanied by soft gluon emission. Using model estimates for the associated hadronic parameter Λ(17)(u), we predict a value in the range -0.6% < A(X(s)γ)(SM) < 2.8%. In view of current experimental data, a future precision measurement of the flavor-averaged CP asymmetry would signal the presence of new physics only if a value below -2% was found. A cleaner probe of new physics is offered by the difference of the CP asymmetries in charged versus neutral B→X(s,d)γ decays.     

Study of the photon’s pole structure in the noncommutative Schwinger model

The photon magnetic moment for radiation propagating in magnetized vacuum is defined as a pseudotensor quantity, proportional to the external electromagnetic field tensor. After expanding the eigenvalues of the polarization operator in powers of \(k^2\) , we obtain approximate dispersion equations (cubic in \(k^2\) ), and analytic solutions for the photon magnetic moment, valid for low momentum and/or large magnetic field. The paramagnetic photon experiences a redshift, with opposite sign to the gravitational one, which differs for parallel and perpendicular polarizations. It is due to the drain of photon transverse momentum and energy by the external field. By defining an effective transverse momentum, the constancy of the speed of light orthogonal to the field is guaranteed. We conclude that the propagation of the photon non-parallel to the magnetic direction behaves as if there is a quantum compression of the vacuum or a warp of space-time in an amount depending on its angle with regard to the field.     

Radiative decays of scalar mesons σ(600), f 0(980) and a 0(980) in the local Nambu-Jona-Lasinio model

The two-photon decay widths of scalar mesons σ(600), f ₀(980) and a ₀(980) as well a ₀ → ju(ω)γ and f ₀ → ju(ω)γ are calculated in the framework of the local Nambu-Jona-Lasinio model. The contributions of the quark loops (Hartree-Fock approximation) and the meson loops (next 1/N _c -approximation where N _c is the number of colors) are taken into account. The values of these contributions, as we show, are of the same order of magnitude. For the f ₀ decay the K-loop contribution plays the dominant role. The results for two-gamma decays are in satisfactory agreement with modern experimental data. The predictions for a ₀ → ju(ω)γ and f ₀ → ju(ω)γ widths are given.     

Precision measurement of the (3p–1s) X-ray transition in muonic hydrogen

The (3p — 1s) X-ray transition to the muonic hydrogen ground state was measured with a highresolution crystal spectrometer. The assumption of a statistical population of the hyperfine levels of the muonic hydrogen ground state was directly confirmed by the experiment and measured values for the hyperfine splitting can be reported. The measurement supplements studies on line broadening effects induced by Coulomb de-excitation hindering the direct extraction of the pion-nucleon scattering lengths from pionic hydrogen and deuterium X-ray lines.     

Study of f 0(980) and f 0(1500) from B s →f 0(980)π,f 0(1500)π decays

In this paper, we analyze the scalar mesons f ₀(980) and f ₀(1500) from the decays $\bar{B}^{0}_{s}\to f_{0}(980)\pi^{0},\allowbreak f_{0}(1500)\pi^{0}$ within Perturbative QCD approach. From the leading-order calculations, we find that (a) in the allowed mixing angle ranges, the branching ratio of $\bar{B}^{0}_{s}\to f_{0}(980)\pi^{0}$ is about (1.0～1.6)×10^?7, which is smaller than that of $\bar{B}^{0}_{s}\to f_{0}(980)K^{0}$ (the difference is a few times even one order); (b) the decay $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ is better to distinguish between the lowest lying state or the first excited state for f ₀(1500), because the branching ratios for two scenarios have about one-order difference in most of the mixing angle ranges; and (c) the direct CP asymmetries of $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ for two scenarios also exists great difference. In scenario II, the variation range of the value ${\mathcal{A}}^{\mathrm{dir}}_{CP}(\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0})$ according to the mixing angle in scenario II is very small, except for the values for mixing angles near 90° or 270°, while the variation range of ${\mathcal{A}}^{\mathrm{dir}}_{CP}(\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0})$ in scenario I is very large. Compared with the future data for the decay $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ , it is easy to determine the nature of the scalar meson f ₀(1500).     

Inclusive production of baryons in decays of the γ (9.46) and in quark jets

Inclusive Production of mesons and baryons in quark jets at \(\sqrt s = 9.5 \ldots 36GeV\) and in decays of the γ(9.46) meson has been studied using the Quark Recombination Model (QRM). The model predictions for quark jets agree with data. The QRM-simulation of three-gluon decays of the γ(9.46) shows an enhancement of the inclusive baryon rate, as was observed recently by the DASP II experiment.     

On the possibility of observation of a 0-f 0 mixing in the pn → da 0 reaction

It is shown that, if isospin is not conserved in a ₀ ⁰ -and f ₀-meson mixing, forward-backward asymmetry arises in the pn→da ₀ ⁰ reaction. This effect increases near the reaction threshold. The asymmetry is estimated within the framework of a model in which the a ₀ ⁰ -f ₀ mixing is due to the virtual π⁰?η transition and the difference in masses of the charged and neutral kaons in decay channels. The angular asymmetry near the threshold of the pn→da ₀ ⁰ reaction was found to be large, of the order of 8–15%.     

On the implication of Bell’s probability distribution and proposed experiments of quantum measurement

In derivating of Bell’s inequalities, the probability distribution is supposed to be a function only of a hidden variable. We point out that the true implication of the probability distribution of Bell’s correlation function is the distribution of joint measurement outcomes on the two sides. It is therefore a function of both the hidden variable and the settings. In this case, Bell’s inequalities fail. Our further analysis shows that Bell’s locality holds neither for dependent events nor for independent events. We think that the measurements of EPR pairs are dependent events, and hence violation of Bell’s inequalities cannot rule out the existence of local hidden variable. To explain the results of EPR-type experiments, we suppose that a polarization-entangled photon pair can be composed of two circularly or linearly polarized photons with correlated hidden variables, and a couple of experiments of quantum measurement are proposed. The first uses delayed measurement on one photon of the EPR pair to demonstrate directly whether measurement on the other could have any nonlocal influence on it. Then several experiments are suggested to reveal the components of the polarization-entangled photon pair. The last one uses successive polarization measurements on a pair of EPR photons to show that two photons with the same quantum state behave the same under the same measuring conditions.     

Study of pure annihilation decays B_(d,s)→D~0~0

Within the heavy quark limit and the hierarchy approximation λQCD mD mB, we analyze the B → D00 and Bs → D00 decays, which occur purely via annihilation type diagrams. As a rough estimate, we calculate their branching ratios and CP asymmetries in the perturbative QCD (PQCD) approach. The branching ratio of B → D00 is about 3.8×10-5 that is just below the latest experimental upper limit. The branching ratio of Bs → D00 is about 6.8×10-4, which could be measured in LHC-b. From the calculation, it is found that this branching ratio is not sensitive to the weak phase angle γ. In these two decay modes, there exist CP asymmetries because of the interference between weak and strong interaction. However, these asymmetries are too small to be measured easily.