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C. J. Batty

Publications and source records attributed to C. J. Batty.

14 recordsLinked to original sources
arXiv2011

Partial wave analysis of pbar-p annihilation channels in flight with I=1, C=+1

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.

hep-ex↗
arXiv2011

A partial wave analysis of pbar-p -> eta-eta-pizero

A partial wave analysis of pbar-p -> eta-eta-pizero data from the Crystal Barrel experiment is made in terms of s-channel resonances. The decay channels a_0(980)-eta, f_0(1770)-pi and f_0(2105)-pi provide evidence for two I = 1 J^{PC} = 0^{-+} resonances. The first has mass M =2360 +- 25 MeV and width Gamma = 300^{+100}_{-50} MeV, and the second M =2070 \pm 35 MeV, Gamma = 310^{+100}_{-50} MeV. There is also evidence for a J^{PC} = 2^{-+} state with M = 2005 +- 15 MeV and Gamma = 200 +- 40 MeV, decaying strongly to a_0(980)-pi.

hep-ex↗
arXiv2011

I=0, C=-1 mesons from 1940 to 2410 MeV

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.

hep-ex↗
arXiv2011

Combined analysis of meson channels with I=1, C = -1 from 1940 to 2410 MeV

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.

hep-ex↗
arXiv2011

The f2(1565) in pbar-p -> (omega-omega)pizero interactions at rest

Data are presented on the reaction pbar-p -> omega-omega-pizero at rest from the Crystal Barrel detector. These data identify a strong signal due to f2(1565) -> omega-omega. The relative production from initial pbar-p states 3P2, 3P1 and 1S0 is well determined from omega-omega decay angular correlations; P-state annihilation dominates strongly. A combined fit is made with data on pbar-p -> 3pizero at rest, where f2(1565) -> pizero-pizero is observed.

hep-ex↗
arXiv2011

Resonances formed by pbar-p and decaying into pizero-pizero-eta for masses 1960 to 2410 MeV

Data on pbar-b annihilation in flight into pizero-pizero-eta are presented for nine beam momenta 600 to 1940 MeV/c. The strongest four intermediate states are found to be f_2(1270)-eta, a_2(1320)-pi, sigma-eta and a_0(980)-pi. Partial wave analysis is performed mainly to look for resonances formed by pbar-p and decaying into pizero-pizero-eta through these intermediate states. There is evidence for the following s-channel I = 0 resonances : two 4^{++} resonances with mass and width (M,Gamma) at (2044, 208) MeV and (2320+-30, 220+-30) MeV; three 2^{++} resonances at (2020+-50, 200+-70) MeV, (2240+-40, 170+-50) MeV and (2370+-50, 320+-50) MeV; two 3^{++} resonances at (2000+-40, 250+-40) MeV and (2280+-30, 210+-30) MeV; a 1^{++} resonance at (2340+-40, 340+-40) MeV; and two 2^{-+} resonances at (2040+-40, 190+-40) MeV and (2300+-40, 270+-40) MeV.

hep-ex↗
arXiv2011

Partial wave analysiss of pbar-p -> piminus-piplus, pizero-pizero, eta-eta and eta-etaprime

A partial wave analysis is presented of Crystal Barrel data on pbar-p -> pizero-pizero, eta-eta and eta-etaprime from 600 to 1940 MeV/c, combined with earlier data on dσ/dΩand P for pbar-p->piminus-piplus. The following s-channel I=0 resonances are identified: (i) J^{PC} = 5^{--} with mass and width (M,Γ) at (2295+-30,235^{+65}_{-40}) MeV, (ii) J^{PC} = 4^{++} at (2020+-12, 170+-15) MeV and (2300+-25, 270+-50) MeV, (iii) 3D3 JPC = 3^{--} at (1960+-15, 150+-25) MeV and (2210+-4$, 360+-55) MeV, and a 3G3 state at (2300 ^{+50}_{-80}, 340+-150) MeV, (iv) JPC = 2^{++} at (1910+-30, 260+-40) MeV, (2020+-30, 275+-35) MeV, (2230+-30, 245+-45) MeV, and (2300+-35, 290+-50) MeV, (v) JPC = 1^{--} at (2005+-40, 275+-75) MeV, and (2165+-40, 160 ^{+140}_{-70}) MeV, and (vi) JPC = 0^{++} at (2005+-30, 305+-50) MeV, (2105+-15, 200+-25) MeV, and (2320+-30, 175+-45) MeV. In addition, there is a less well defined 6^{++} resonance at 2485+-40 MeV, with Gamma = 410+-90 MeV. For every JP, almost all these resonances lie on well defined linear trajectories of mass squared v. excitation number. The slope is 1.10+-0.03 Gev^2 per excitation. The f_0(2105) has strong coupling to eta-η, but much weaker coupling to pizero-pizero. Its flavour mixing angle between q-qbar and s-sbar is (59-71.6)deg, i.e. dominant decays to s-sbar. Such decays and its strong production in pbar-p interactions strongly suggest exotic character.

hep-ex↗
arXiv2011

I = 0 C = +1 mesons from 1920 to 2410 MeV

A combined fit is presented to data on pbar-p annihilation in flight to final states eta-pizero-pizero, pizero-pizero, eta-eta, eta-etaprime and piminus-piplus. The emphasis lies in improving an earlier study of eta-pizero-pizero by fitting data at nine pbar momenta simultaneously and with parameters consistent with the two-body channels. There is evidence for all of the I=0, C=+ q-qbar states expected in this mass range. New resonances are reported with masses and widths M,Gamma as follows: JPC = 4^{-+} (2328+-38, Gamma=240+-90) MeV, 1^{++} (1971+-15, 240+-45) MeV, 0^{-+} (2285+-20, 325+-30) MeV, and 0^{-+} (2010 ^{+35}_{-60}, 270+-60) MeV. Errors on the masses and widths of other resonances are also reduced substantially. All states lie close to parallel straight line trajectories of excitation number v. mass squared.

hep-ex↗
arXiv2010

A fresh look at eta2(1645), eta2(1870), eta2(2030) and f2(1910) in pbar-p -> eta + 3pizero

There is a large discrepancy between results of Crystal Barrel and WA102 for the branching ratio R = BR[eta2(1870)->a2(1320)pi]/ BR[eta2(1870)->f2(1270)eta]. An extensive re-analysis of the Crystal Barrel data redetermines branching ratios for decays of eta2(1870), eta2(1645), eta2(2030) and f2(1910). This re-analysis confirms a small value for R of 1.60+-0.39, inconsistent with the value 32.6+-12.6 of WA102. The likely origin of the discrepancy is that the WA102 data contain a strong f2(1910)->a2-pi signal as well as eta2(1870). There is strong evidence that the eta2(1870) has resonant phase variation. A peak in f2(1270)a0(980) confirms closely the parameters of the a2(2255) resonance observed previously. A peak in eta2(2030)-pi is interpreted naturally in terms of pi2(2245) with reduced errors for mass and width M=2285+-20(stat)+-25(syst) MeV, Gamma=250+-20(stat)+-25(syst) MeV.

hep-ex↗
arXiv2000

Unified optical-model approach to low-energy antiproton annihilation on nuclei and to antiprotonic atoms

A successful unified description of $\bar p$ nuclear interactions near E=0 is achieved using a $\bar p$ optical potential within a folding model, $V_{\rm opt} \sim \bar v * ρ$, where a $\bar p p$ potential $\bar v$ is folded with the nuclear density $ρ$. The potential $\bar v$ fits very well the measured $\bar p p$ annihilation cross sections at low energies ($p_L < 200$ MeV/c) and the $1s$ and $2p$ spin-averaged level shifts and widths for the $\bar p$H atom. The density-folded optical potential $V_{\rm opt}$ reproduces satisfactorily the strong-interaction level shifts and widths over the entire periodic table, for $A > 10$, as well as the few low energy $\bar p$ annihilation cross sections measured on Ne. Both $\bar v$ and $V_{\rm opt}$ are found to be highly absorptive, which leads to a saturation of reaction cross sections in hydrogen and on nuclei. Predictions are made for $\bar p$ annihilation cross sections over the entire periodic table at these very low energies and the systematics of the calculated cross sections as function of $A$, $Z$ and $E$ is discussed and explained in terms of a Coulomb-modified strong-absorption model. Finally, optical potentials which fit simultaneously low-energy $\bar p - ^4$He observables for $E < 0$ as well as for $E > 0$ are used to assess the reliability of extracting Coulomb modified $\bar p$ nuclear scattering lengths directly from the data. The relationship between different kinds of scattering lengths is discussed and previously published systematics of the $\bar p$ nuclear scattering lengths is updated.

nucl-th↗
arXiv2000

Saturation of low-energy antiproton annihilation on nuclei

Recent measurements of very low-energy ($p_{L}<100$ MeV/c) $\bar p$ annihilation on light nuclei reveal apparent suppression of annihilation upon increasing the atomic charge $Z$ and mass number $A$. Using $\bar p$-nucleus optical potentials $V_{\rm opt}$, fitted to $\bar p$-atom energy-shifts and -widths, we resolve this suppression as due to the strong effective repulsion produced by the very absorptive $V_{\rm opt}$. The low-energy $\bar p$-nucleus wavefunction is kept substantially outside the nuclear surface and the resulting reaction cross section saturates as function of the strength of Im $V_{\rm opt}$. This feature, for $E >0$, parallels the recent prediction, for $E < 0$, that the level widths of $\bar p$ atoms saturate and, hence, that $\bar p$ deeply bound atomic states are relatively narrow. Antiproton annihilation cross sections are calculated at $p_{L}=57$ MeV/c across the periodic table, and their dependence on $Z$ and $A$ is classified and discussed with respect to the Coulomb focussing effect at very low energies.

nucl-th↗
arXiv1998

Experiments with $Ξ^-$ atoms

Experiments with $Ξ^-$ atoms are proposed in order to study the nuclear interaction of $Ξ$ hyperons. The production of $Ξ^-$ in the ($K^{-}$, $K^{+}$) reaction, the $Ξ^-$ stopping in matter, and its atomic cascade are incorporated within a realistic evaluation of the results expected for $Ξ^-$ X-ray spectra across the periodic table, using an assumed $Ξ$-nucleus optical potential $V_{opt}$. Several optimal targets for measuring the strong-interaction shift and width of the X-ray transition to the `last' atomic level observed are singled out: F, Cl, I, Pb. The sensitivity of these observables to the parameters of $V_{opt}$ is considered. The relevance of such experiments is discussed in the context of strangeness -2 nuclear physics and multistrange nuclear matter. Finally, with particular reference to searches for the $H$ dibaryon, the properties of $Ξ^-d$ atoms are also discussed. The role of Stark mixing, its effect on $S$ and $P$ state capture of $Ξ^-$ by the deuteron, together with estimates of the resulting probability for producing the $H$ dibaryon are considered in detail.

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