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Register a new userCombined analysis of meson channels with I=1, C = -1 from 1940 to 2410 MeV
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New Crystal Barrel data are reported for pbar-p -> omega-pizero and pbar-p -> omega eta-pizero with omega decaying to piplus-piminus-pizero. The shapes of angular distributions agree well with those for data where omega -> pizero-gamma; this is a valuable cross-check on systematic errors. The new data provide good measurements of vector and tensor polarisations P_y, T20, T21 and T22 of the omega. These lead to significant improvements in parameters of several resonances reported earlier. New values of masses and widths (in Mev) are: J^PC = 5^-- (2300+-45, 260+-75), J^PC = 3^-- (2260+-20, 160+-25), J^PC = 1^+- (2240+-35, 320+-85), and J^PC = 1^-- (2110+-35, 230+-50). A remarkable feature of the data is that vector polarisation P_y is close to zero everywhere. It follows that all interfering amplitudes have relative phases close to 0 or 180 deg. Tensor polarisations are large.
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New Crystal Barrel data are reported for pbar-p -> omega-eta and pbar-p -> omega-pizero-pizero with omega decaying to piplus-piminus-pizero. The omega-eta data confirm angular distributions obtained earlier from data where omega -> pizero-gamma. The new omega-eta data provide accurate measurements of vector and tensor polarisations of the omega and lead to considerable improvements in masses and widths of s-channel resonances. A new J^PC = 3^+- I = 0 resonance is observed with mass M = 2025+-20 MeV and width Gamma = 145+-30 MeV. Polarisation is close to zero everywhere and tensor polarisations are large, as is the case also for pbar-p -> omega-pizero.
A combined analysis is reported of 3pizero, pizero-eta and pizero-etaprime data in the mass range 1960 to 2410 MeV. This analysis is made consistent also with eta-eta-pizero data, reported separately. The analysis requires s-channel resonances with a spectrum close to that published earlier for C = +1 states with I = 0; masses for I=1 states are lower on average by 20 MeV. Two alternative solutions are found, differing only for J^P = 2^+ and 4^+ states by small amounts in masses and widths. Both 3pizero and eta-pizero data prefer one of these two solutions. For this preferred solution, observed states have J^PC, masses and widths (M,Gamma) in MeV as follows: 4^-+: (2250+-15, 215+-25), 4^++: (2255+-40, 330 ^{+110}_{-50}) and (2005 ^{+25}_{-45}, 180+-30), 3^++: (2275+-35, 350 ^{+100}_{-50}) and (2031+-12, 150 pm 18), 2^-+: (2245+-60, 320 ^{+100}_{-40}) and (2005+-15, 200+-40, 2^++: (2255+-20, 230+-15), (2175+-40, 310^{+90}_{-45}) and (2030+-20, 205+-30), and 1^++: (2270 ^{+55}_{-40}, 305 ^{+70}_{-35}). There are indications of further 2^-+, 2^++ and 1^++ contributions just below the available mass range, and also a 0^++ state at ~2025 MeV.
Data on pbar-p -> 3eta for beam momenta 600--1940 MeV/c are presented. The strongest channel is f_0(1500)-eta from the initial pbar-p state 1S0. Together with eta-pizero-pizero data, the 3eta data determine the branching ratio BR[f_0(1500) -> eta-eta]/BR[f_0(1500) -> pizero-pizero] = 0.42+-0.09. They are consistent with a dominant contribution from an I=0, C=+1 J^{PC} = 0^{-+} resonance observed earlier in the eta-pizero-pizero data; from the combined eta-pizero-pizero and 3eta data, its mass is M = 2320 pm 15 MeV and its width Gamma = 230+-35 MeV.
We present the first search for bosonic super-WIMPs as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-beta decay experiment which operates high-purity germanium detectors enriched in $^{76}$Ge in an ultra-low background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from 60 keV/c$^2$ to 1 MeV/c$^2$. No evidence for a dark matter signal was observed, and the most stringent constraints on the couplings of super-WIMPs with masses above 120 keV/c$^2$ have been set. As an example, at a mass of 150 keV/c$^2$ the most stringent direct limits on the dimensionless couplings of axion-like particles and dark photons to electrons of $g_{ae} < 3 cdot 10^{-12}$ and ${alpha}/{alpha} < 6.5 cdot 10^{-24}$ at 90% credible interval, respectively, were obtained.
A recent analysis of data on the two photon production of the $eta_c$ and its decay to $K(Kpi)$ has determined the $Kpi$ $S$-wave amplitude in a model-independent way assuming primarily that the additional kaon is a spectator in this decay. The purpose of this paper is to fit these results, together with classic $Kpi$ production data from LASS, within a formalism that implements unitarity for the di-meson interaction. This fixes the $I=1/2$ $Kpito Kpi$ $S$-wave amplitude up to 2.4 GeV. This resolves the Barrelet ambiguity in the original LASS analysis, and constrains the amount of inelasticity in $Kpi$ scattering, highlighting that this becomes significant beyond 1.8 GeV. This result needs to be checked by experimental information on the many inelastic channels, in particular $Keta^prime$ and $Kpipipi$. Our analysis provides a single representation for the $Kpi$ $S$-wave from threshold, controlled by Chiral Perturbation Theory, through the broad $kappa$, $K_0^*(1430)$ and $K_0^*(1950)$ resonances. There is no arbitrary sum of Breit-Wigner forms and random backgrounds for real $Kpi$ masses. Rather the form provides a representation that can be translated to other processes with $Kpi$ interactions with their own coupling functions, while automatically maintaining consistency with the chiral dynamics near threshold, with the LASS data and the new results on $eta_c$ decay.
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