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Register a new userThe Comparative Study of the Inclusive $pi^0$ Analyzing Power in Reactions p+p(pol)->pi^0 + X and pi^-+p(pol)->pi^0 + X at 50 and 40 Gev/C Respectively
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Single-spin asymmetries $A_N$ in reactions p+p(pol)->pi^0 + X and pi^-+p(pol)->pi^0 + X at 50 and 40 GeV/c respectively behave in drastically different ways in function of transverse momentum in the central region. At the same time $A_N$ in the polarized proton fragmentation region of these reactions are practically coinciding. Our new data on the analyzing power at 50 GeV/c in the polarized proton fragmentation region in reaction p+p(pol)->pi^0 + X confirm this conclusion with better statistics and coincide with our previous data at 70 GeV/c for the same reaction.
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We present recent results of single-spin asymmetry $A_N$ measurements in $pi^0$ inclusive production. Asymmetry was measured in $pi^-p$ and $pp$ interactions at 40 and 70 GeV correspondingly. Significant asymmetry was observed in the polarized target fragmentation region. The results are in agreement with universal threshold of single-spin asymmetry.
A partial wave analysis of antiproton-proton annihilation data in flight at 900 $MeV/c$ into $pi^0 pi^0 eta$ , $pi^0 eta eta$ and $K^+ K^- pi^0$ is presented. The data were taken at LEAR by the Crystal Barrel experiment in 1996. The three channels have been coupled together with $pipi$-scattering isospin I=0 S- and D-wave as well as I=1 P-wave data utilizing the K-matrix approach. Analyticity is treated using Chew-Mandelstam functions. In the fit all ingredients of the K-matrix, including resonance masses and widths, were treated as free parameters. In spite of the large number of parameters, the fit results are in the ballpark of the values published by the Particle Data Group. In the channel $pi^0 pi^0 eta$ a significant contribution of the spin exotic $I^G=1^-$ $J^{PC}=1^{-+}$ $pi_1$-wave with a coupling to $pi^0 eta$ is observed. Furthermore the contributions of $phi(1020) pi^0$ and $K^*(892)^pm K^mp$ in the channel $K^+ K^- pi^0$ have been studied in detail. The differential production cross section for the two reactions and the spin-density-matrix elements for the $phi(1020)$ and $K^*(892)^pm$ have been extracted. No spin-alignment is observed for both vector mesons. The spin density matrix elements have been also determined for the spin exotic wave.
A search for $C!P$ violation in the $Lambda_b^0 to p pi^- pi^+ pi^-$ decay is performed using LHCb data corresponding to an integrated luminosity of 6.6$,fb^{-1}$ collected in $pp$ collisions at centre-of-mass energies of 7, 8 and 13$,Tekern -0.1em V$. The analysis uses both triple product asymmetries and the unbinned energy test method. The highest significances of $C!P$ asymmetry are 2.9 standard deviations from triple product asymmetries and 3.0 standard deviations for the energy test method. Once the global $p$-value is considered, all results are consistent with no $C!P$ violation. Parity violation is observed at a significance of $5.5$ standard deviations for the triple product asymmetry method and $5.3$ standard deviations for the energy test method.
We have searched for the Cabibbo-suppressed decay $Lambda_c^+tophi ppi^0$ in $e^+e^-$ collisions using a data sample corresponding to an integrated luminosity of 915 $rm fb^{-1}$. The data were collected by the Belle experiment at the KEKB $e^+e^-$ asymmetric-energy collider running at or near the $Upsilon(4S)$ and $Upsilon(5S)$ resonances. No significant signal is observed, and we set an upper limit on the branching fraction of $mathcal{B}(Lambda_c^+to phi ppi^0) <15.3times10^{-5}$ at 90% confidence level. The contribution for nonresonant $Lambda_c^+to K^+K^- ppi^0$ decays is found to be consistent with zero and the corresponding upper limit on its branching fraction is set to be $mathcal{B}(Lambda_c^+to K^+K^-ppi^0)_{rm NR} <6.3times10^{-5} $ at 90% confidence level. We also measure the branching fraction for the Cabibbo-favored decay $Lambda_c^+to K^-pi^+ppi^0$; the result is $mathcal{B}(Lambda_c^+to K^-pi^+ppi^0)= (4.42pm0.05, (rm stat.) pm 0.12, (rm syst.) pm 0.16, (mathcal{B}_{rm Norm}))%$, which is the most precise measurement to date. Finally, we have searched for an intermediate hidden-strangeness pentaquark decay $P^+_stophi p$. We see no evidence for this intermediate decay and set an upper limit on the product branching fraction of ${cal B}(Lambda_c^+to P^+_s pi^0)times {cal B}(P^+_stophi p) <8.3times 10^{-5}$ at 90% confidence level.
Using data samples collected with the BESIII detector at center-of-mass energies $sqrt{s} = 4.23, 4.26, 4.36,$ and $4.42$~rm{GeV}, we measure the branching fractions of $eta_cto K^+K^-pi^0$, $K^0_S K^{pm}pi^{mp}$, $2(pi^+pi^-pi^0)$, and $p bar{p}$, via the process $e^+e^-topi^+pi^-h_c$, $h_ctogammaeta_c$. The corresponding results are $(1.15pm0.12pm0.10)%$, $(2.60pm0.21pm0.20)%$, $(15.2pm1.8pm1.7)%$, and $(0.120pm0.026pm0.015)%$, respectively. Here the first uncertainties are statistical, and the second ones systematic. Additionally, the charged track multiplicity of $eta_c$ decays is measured for the first time.
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