We present the results of a study of the charmless vector-vector decay B0->wK*0 with 657x10^6 BB(bar) pairs collected with the Belle detector at the KEKB e+e- collider. We measure the branching fraction to be B(B0->wK*0)=[1.8+/-0.7(stat)+/-0.3(syst)]x10^-6 with 3.0sigma significance. We also perform a helicity analysis of the w and K*0 vector mesons, and obtain the longitudinal polarization fraction fL(B0->wK*0)=0.56+/-0.29(stat)+0.18-0.08(syst). Finally, we measure a large non-resonant branching fraction B[B->wK+pi-; M(Kpi)\in(0.755,1.250) GeV/c^2]=[5.1+/-0.7(stat)+/-0.7(syst)]x10^-6 with a significance of 9.5sigma.
Separation of a single photon and products of the $π^0,η, K^0_s$ meson neutral decay channels in the CMS electromagnetic calorimeter using neural network
Results are presented for the transverse single-spin asymmetries of direct photons, neutral pions, and eta mesons for $|η|<0.35$ from $p^\uparrow + p$ collisions with $\sqrt{s} = 200$ GeV at PHENIX. As hadrons, $π^0$ and $η$ mesons are sensitive to both initial- and final-state effects and at midrapidity probe the dynamics of gluons along with a mix of quark flavors. Because direct photon production does not include hadronization, the direct photon TSSA is only sensitive to initial-state effects and at midrapidity provides a clean probe of the gluon dynamics in transversely polarized protons. …
We measure the $D^0 - {\bar{D}}^0$ mixing parameters using a time-dependent amplitude analysis of the decay $D^0\toπ^+π^-π^0$. The data were recorded with the BABAR detector at center-of-mass energies at and near the $Υ(4S)$ resonance, and correspond to an integrated luminosity of approximately 468.1 ${\rm fb}^{-1}$. The neutral $D$ meson candidates are selected from $D^{*}(2010)^+\to D^0 π_s^+$ decays where the flavor at the production is identified by the charge of the low momentum pion, $π_s^+$. The measured mixing parameters are $x = (1.5\pm1.2\pm0.6) \%$ and $y = (0.2\pm0.9\pm0.5) \%$, wh…
By extending the well-known Weinberg's prescriptions on the diagonalization of the mass term of the Lagrangian without increasing the total number of entities, we get the following conclusions: the set of neutral $K$-mesons consists of two elements, $K_{S}^{0}$ and $K_{L}^{0}$; the states $K^{0}$ and $\bar{K}^{0}$ do not exist as physical objects (in the form of particles or "particle mixtures"); the absence of the states $K^{0}$ and $\bar{K}^{0}$ destroys the grounds for introducing the notion of their oscillations, further replicated as the neutrino oscillation concept. The conclusions conce…
The recent precision measurement of the relative yield of $D^+D^-$ and $D^0 \bar D^0$ meson pairs at the $ψ(3770)$ peak in $e^+e^-$ annihilation is about 3.7 sigma away from a straightforward theoretical estimate. It is argued that combined with an even more significant deviation of similar ratio for the $B$ mesons at the $Υ(4S)$ peak, this provides an insight into the structure of heavy mesons and requires both a form factor, corresponding to their finite `size', and a strong interaction between the mesons mesons in the isovector state $I^G(J^P) = 1^+(1^-)$. It is also argued that the data fo…
A direct test of T symmetry in the neutral K meson system with Ks->pi l nu and Kl->3pi0 at KLOE-2
K介子和B介子的量子纠缠允许直接的时间反演对称性的实验测试独立于CP破坏。T对称性可以通过介子的味态和CP定态之间的可逆跃迁中的初态和终态的交换来探测，这些介子仅由T共轭连接。虽然BaBar实验成功地用中性B介子进行了这样的测试，但KLOE-2探测器可以通过研究Ks->pi 1 nu和Kl-> 3 pi 0衰变过程来探测中性K介子系统中的T破坏。对后者的分析是通过一种新的重建方法来促进的K1-> 3 pi 0衰变的顶点，其中只涉及中性粒子。这种新的顶点重建技术的细节，以及进行直接的T对称性测试在KLOE-2实验的前景。
In these proceedings we present the latest results from ALICE on direct photon and light neutral meson production in p$-$Pb and Pb$-$Pb collisions. The direct photon excess ratio $R_γ$ in different charged particle multiplicity classes of p$-$Pb collisions at $\sqrt{s_{\tiny{NN}}}=5.02\,\mathrm{TeV}$ is shown. In addition, we present the direct photon elliptic flow coefficient $v_2$ in central and semicentral events of Pb$-$Pb collisions at $\sqrt{s_{\tiny{NN}}}=2.76\,\mathrm{TeV}$. An outlook on ongoing and future measurements is given.
We investigate the rare electromagnetic decays of neutral vector mesons (exemplified by $J/ψ$, $Υ$, $ρ^0$, $ω,ϕ$, \ldots) into four charged leptons ($2(e^+e^-)$, $2(μ^+μ^-)$, $2(τ^+τ^-)$, $e^+e^-μ^+μ^-$, $e^+e^-τ^+τ^-$, \ldots) at lowest order in QED. In contrast to the case of vector meson decay into a single pair of leptons, the lepton mass must be retained in these four-lepton decay channels to cutoff the mass singularity. Owing to more pronounced collinear enhancement, the branching fractions of vector mesons decays into $ 2(e^+e^-)$ are considerably greater than those for decays into $2(μ…
We present the measurement of light neutral mesons, $π^{0}$ and $η$, in pp collisions at different center-of-mass energies obtained with the ALICE experiment at the LHC. The $π^{0}$ and $η$ mesons are measured via photons reconstructed by the electromagnetic calorimeters and the central tracking system. The invariant cross-section of $π^{0}$ and $η$ mesons are measured in a broad $p_{\rm T}$ range at $\sqrt{s} = 0.9, 2.76, 7, 5.02$ and 8 TeV. The spectra of $π^{0}$ and $η$ mesons measured in pp collisions at different collision energies show $x_{\rm T}$-scaling at high $p_{\rm T}$ and violatio…
Based on the mechanism of neutral meson mixing, we predict the branching fraction of the semileptonic decay of $D_s^+\to π^0 \ell^+ ν_\ell$ ($\ell=e$, $μ$) using recently measured branching fraction of $D_s^+\to ηe^+ν_e$ by BESIII experiment . We also give a formula that can describe the neutral meson mixing of $π^0$, $η$, $η'$ and a pseudoscalar gluonium $G$ in a unified way. The predicted branching fraction of $D_s^+\toπ^0 e^+ν_e$ decay is $\mathcal{B}(D_s^+\toπ^0 e^+ν_e)=(2.65\pm 0.38)\times 10^{-5}$. It is important to search for the decay $D_s^+\to π^0 \ell^+ ν_\ell$ in experiment, in ord…
The first measurements of the invariant differential cross sections of inclusive $π^0$ and $η$ meson production at mid-rapidity in proton-proton collisions at $\sqrt{s}=0.9$ TeV and $\sqrt{s}=7$ TeV are reported. The $π^0$ measurement covers the ranges $0.4<p_T<7$ GeV/$c$ and $0.3<p_T<25$ GeV/$c$ for these two energies, respectively. The production of $η$ mesons was measured at $\sqrt{s}=7$ TeV in the range $0.4<p_T<15$ GeV/$c$. Next-to-Leading Order perturbative QCD calculations, which are consistent with the $π^0$ spectrum at $\sqrt{s}=0.9$ TeV, overestimate those of $π^0$ and $η$ mesons at …
CP violation in neutral $B$ meson oscillations is an experimental observable that could be directly related to the baryon asymmetry of the Universe through the $B$-Mesogenesis mechanism. As this phenomenon is highly suppressed in the Standard Model, it could also be a sensitive probe for many new physics scenarios that modify neutral meson mixing. Motivated by these facts, and the timely $B$ physics program at the LHC and Belle II, we analyze how large CP violation in the mixing of neutral $B_d$ and $B_s$ meson systems could be. We answer this question, in light of current experimental data, w…
