Measurement of the branching ratios for the decays J/ψ → ϱπ and J/ψ → γη′

Decays of the J/ψ (3.1) resonance into final states with two charged hadrons and two photons are investigated. Branching ratios for the decays J/ψ → ?π and J/ψ → γη′ are determined to be

$\text{Г(J/ψ → pφ)}\text{Г(J/ψ → all)}\text{= (1.0± 0.2) ·10}{}^{\mathrm{?2}}\text{,}\text{Г(J/ψ → γη′)}\text{ГJ/ψ → all)}\text{= (2.0± 0.7) ·}{}^{\mathrm{?3}}$

Upper limits for the same decay modes of ψ′ (3.7) are also determined.     

Experimental comparison of Jψ production by π±, K±, p and p̄ beams at 39.5 GeV/c

Measurements have been made of relative production cross sections of the $\text{J}\text{ψ}$ by π^±, K^±, p and p? at 39.5 GeV/c incident on copper. $\text{J}\text{ψ}$ production rates from π^?, K^? and p? are similar. The $\text{J}\text{ψ}$ relative particle/anti-particle production cross sections for x>0 are $\text{σ(π}{}^{\mathrm{+}}\text{)}\text{σ(π}{}^{\mathrm{?}}\text{)=(0.87±0.14)}$, σ(K⁺)/σ(K^?)=(0.85±0.5) and $\text{σ(}\text{p}\text{)}\text{σ(}\text{p}\text{?}\text{)=(0.15 ±0.08)}$. The small p/p? cross section ratio disagrees with models of J/ψ production by gluon amalgamation.     

Experimental results on J/ψ production by π±, K±, p and p incident on hydrogen at 39.5 GeV/c

J/ψ production at 40 GeV/c by π^±, K^±, p and $\text{p}$ incident on hydrogen has been studied and results compared with those obtained on tungsten in the same experiment. On hydrogen, J/ψ cross-section ratios relative to π^? have been measured to be (for $\text{x}{}_{\mathrm{<mtext>F</mtext>}}\text{> 0) σ(π}{}^{\mathrm{?}}\text{) : σ(π}{}^{\mathrm{+}}\text{) : σ(}\text{p}\text{) : σ(}\text{p}\text{) = 1 : (0.78 ± 0.09) : (0.83 ± 0.35) : (0.07 ± 0.04)}$. The suppression of the proton induced cross sections shows the importance of calence quark-antiquark fusiin J/ψ production at this energy (i.e. M_J²/_ψ/s=0.13).     

Jψ and ψ′ decays into two hadrons

Branching ratios have been determined for the decays of $\text{J}\text{ψ}$ and ψ ′ into π⁺π^?, K⁺K^?, $\text{p}\text{p}$, π^±?^? and $\text{K}{}^{\mathrm{\pm }}\text{K}{}^1\text{(892)}{}^{\mathrm{?}}$. Results on a search for other two body decays of $\text{J}\text{ψ}$ and ψ′ are given. Also presented are values for the π and K from factors at $\text{s}\text{= 3.1}\text{and}\text{3.7}\text{GeV}$.     

Jψ radiative decays into ππγ and KKγ

The radiative decays of $\text{J}\text{ψ}$ into f/γ, f′γ, ππγ and KKγ have been measured using the double arm spectrometer DASP at DORIS. We find B(J/φ→fγ)=(J/φ→fγ)/(J/φ→all)=(0.9±0.3)×10^?3 to (1.5±0.4)×10^?3 depending on the multi- pole mode of the $\text{J}\text{ψ}$ decay and that $\text{B(}\text{J}\text{/φ→}\text{f}\text{′γ)}\text{B(}\text{J}\text{/γ→}\text{f}\text{γ)?}\text{1}\text{3}$.     

Vector meson pole dominance in Jψ decays into mesons

The validity of the assumption that $\text{J}\text{ψ}$ decays into mesons proceed via ω, φ and ?⁰ poles followed by cascade decays is examined. $\text{Λ(}\text{J}\text{ψ}\text{→}\text{B}\text{π)}$ is well reproduced by using $\text{Λ(}\text{J}\text{ψ}\text{→ ?π), Λ(ω → ?π), Λ(}\text{B}\text{→ ωπ)}$ and the B → ωπ helicity structure. The structure of OZI-violating $\text{J}\text{ψ}\text{?}\text{V}{}^0$ transitions including the electromagnetic contribution is examined, and compared with the data on inclusive $\text{J}\text{ψ}$ decay.     

A determination of the spin of the hypernucleus 12ΛB: (II). A complete analysis

The probability distribution calculated for the decay sequence ${}^{12}{}_{\mathrm{\Lambda }}\text{B(g.s.) →}{}^{12}\text{C}{}^1\text{π}{}^{\mathrm{?}}\text{→ αααπ}{}^{\mathrm{?}}$ passing through the (J^P_N) = (2⁺, 1) intermediate state ¹²C¹ (16.11 MeV) is cast in a symmetrical form and used to calculate the likelihood for $\text{J = 1}\text{relative to}\text{J = 2}\text{for}{}^{12}{}_{\mathrm{\Lambda }}\text{B(g.s.}\text{)}$ on the basis of the 85 examples available for this decay process. This procedure has optimum sensitivity, is free from the uncertainties of the comparisons previously made using only projected angular distributions, and strongly indicates that J^P = 1^? holds for ¹²_ΛB(g.s.). An appendix points out that all the data for the decay sequence passing through the (J^P_N, T) = (1⁺, 0) level of ¹²C¹ is well fitted for J = 1 if the J = 1 → J_n = 1 transition amplitude a_s1 takes a value in the range a_s1/s = 0.08 to 0.09.     

Isospin violation in the standard model and the decay F+ → π+π0

The decay F⁺ → π⁺π⁰ can proceed via isospin violating mechanisms similarly to $\text{ψ′ →}\text{J}\text{ψπ}{}^0$. I estimate that π⁰-η-′ mixing together with symmetry breaking in the amplitude lead to Γ(F⁺ → π⁺π⁰)/Γ(F⁺ → π⁺η) = (2.2 ± 0.7) × 10^?3 or (1.0 ± 0.3) × 10^?3, if annihilation processes dominate nonleptonic charmed meson decays. These values correspond to different assumptions for two-meson production in F decays.     

The 2425 keV state in 21Na as a subtreshold resonance in 20Ne (p,γ)21 Na

The high-energy tail of the $\text{J}{}^{\mathrm{\pi }}\text{=}\text{1}\text{2}{}^{\mathrm{+}}$, 2425 keV state in ²¹Na, bound by 7 keV against proton decay, has been observed in the ²⁰Ne (p,γ)²¹Na reaction at E_p=0.5?1.5 MeV. The observed excitation function is consistent with a single-level Breit-Wigner shape with Γ_γ=0.31±0.07 eV at E_x = 2425 keV.     

Missing transverse energy events and the standard model

The processes $\text{p+}\text{p}\text{→ W}{}^{\mathrm{\pm }}$, Z⁰+0,1,2 jets are studied in the light of recent observations of events with large missing transverse momentum at the CERN p$\text{p}$ collider. We find that a nontrivial number of such events can arise from the leptonic decays $\text{Z}{}^0\text{→ ν}\text{ν}$ and W^± → ?^±ν where the charged lepton escapes identification. In both cases the number of events with one jet and with two jets are comparable. By correlating these decay modes with those where the leptons are observed we can, in principle, eliminate the theoretical uncertainties inherent in such perturbative QCD calculations.     

Results on the production cross sections π−p → neutrals and π− p→ χ↳2γ0n at 3.8, 6, 8 and 12 GeV/c

The ratio between the cross sections for the reactions $\text{π}{}^{\mathrm{?}}\text{p→}\text{χ}\text{?}{}_{\mathrm{2\gamma }}{}^0\text{n}$ and π^?p → η_→2γ n has been measured to be (2.4 ± 0.9) × 10^?2, (2.1 ± 0.6) × 10^?2 and (2.8 ± 1.3) × 10^?2 at 3.8,6,8 and 12 GeV/c incident momentum respectively.At the same momenta the cross section for π^t- p → neutrals is (1.48 ± 0.09) mb, (0.86 ± 0.05) mb, (0.64 ± 0.04) mb and (0.42±0.03) mb.     

Measurement of Cl and N quadrupole coupling in ClCN

J = 1 ← 0 and J = 2 ← 1 transitions in ³⁵ClCN and ³⁷ClCN were measured using a C-band waveguide spectrometer and phase-locked sources. Parameters obtained from the data are: $\text{B(}{}^{35}\text{ClCN) = 5 970.820 ± 0.010 MHz}$, $\text{B(}{}^{37}\text{ClCN) = 5 847.246 ± 0.008 MHz}$, $\text{eqQ(}{}^{35}\text{Cl) = ?83.26 ± 0.04 MHz}$, $\text{eqQ(}{}^{37}\text{Cl) = ?65.61 ± 0.04 MHz}$ and $\text{eqQ(}{}^{14}\text{N) = ?3.60 ± 0.08 MHz}$.     

An unambiguous Jπ assignment from γ-rays produced in heavy-ion reactions; The lowest Jπ=6+, 38Ar level

Angular correlation measurements with a Compton-suppression spectrometer in combination with polarization measurements with a three-crystal Ge(Li) Compton polarimeter of γ-rays produced in the ${}^{24}\text{Mg(}{}^{16}\text{O, 2pγ)}{}^{38}\text{Ar}$ reaction result in an unambiguous J^π = 6⁺ assignment to the 6408.3 ± level. It is exclusive decay to the 5^?, 4.59 MeV level is discussed.     

High-spin states in 40K investigated with the 26MG + 16O reaction

Yrast levels in ⁴⁰K and ⁴⁰Ar have been investigated with the ²⁶Mg(¹⁶O, pnγ)⁴⁰K and ²⁶Mg(¹⁶O, 2pγ)⁴⁰Ar reactions at a beam energy of 34 MeV. Gamma-ray angular distribution and γ-γ coincidence measurements have been performed with a high-resolution large volume Ge(Li)-NaI(Tl) Compton-suppression spectrometer. Gamma-ray linear polarizations have been measured with a three-crystal Ge(Li) Compton polarimeter. The ⁴⁰K decay scheme involves new high-spin levels at E_tx = 4365.6±0.3, 4875.6±0.4 and 6227.0±0.5 keV with lifetime limits of < 1, < 1 and < 2ps, respectively. Unambiguous spin-parity assignments of $\text{J}{}^{\mathrm{\pi }}\text{= 5}{}^{\mathrm{?}}\text{, 6}{}^{\mathrm{+}}\text{, 8}{}^{\mathrm{+}}\text{, 9}{}^{\mathrm{+}}\text{and}\text{(8, 10)}{}^{\mathrm{?}}$ to the ⁴⁰K levels at E_x = 0.89, 2.88, 4.37, 4.88 and 6.23 and of $\text{J}{}^{\mathrm{\pi }}\text{= 4}{}^{\mathrm{+}}\text{and}\text{6}{}^{\mathrm{+}}\text{to the}{}^{40}\text{Ar}$ levels at E_x = 2.89 and 3.46 MeV, respectively, have been obtained. Branching ratios and multipole mixing ratios are reported.     

An isomeric two-particle state in 236U

A new isomeric state with 125 ± 20 ns half-life has been found in a ²³⁵U(d, pγ)²³⁶U experiments. Of the 12 observed delayed λ-lines, 11 have been fitted into a tentative decay scheme. The isomeric level is deduced to be the K, J^π = 4,4^? two-quasineutron state at 1052 keV with configuration $\text{[743]}\text{7}\text{2}{}^{\mathrm{?}}$; $\text{[631]}\text{1}\text{2}{}^{\mathrm{+}}$ that is also seen in (d, p) experiments.     

Proton-antiproton annihilations at rest into π0ω, π0η, π0γ, π0π0, and π0η′

Proton-antiproton annihilations at rest in liquid hydrogen were investigated through the inclusive γ spectrum, related to the annihilation. The high-energy part of the spectrum was used to deduce branching ratios for the so far unobserved annihilation channels: $\text{R(}\text{p}\text{p}\text{→π}{}^0\text{ω) = (2.38 ± 0.65)\%}$, $\text{R(}\text{p}\text{p}\text{→ π}{}^0\text{η) = (0.82 ± 0.10\%}$, $\text{R}\text{p}\text{p}\text{→π}{}^{\mathrm{0\gamma )}}\text{= (0.015 ± 0.007)\%}$, and $\text{R(}\text{p}\text{p}\text{→ π}{}^0\text{π}{}^0\text{= (0.06 ± 0.04)\%}$. An upper limit for the π⁰η^′ channel was deduced to be $\text{R(}\text{p}\text{p}\text{→ π}{}^0\text{η}{}^{\mathrm{\prime }}\text{) < 1.1\%}$.     

Hyperfine structure of CH3OH

Hyperfine structure of the (0, 0, 1) - (1, 0, 1) transition of methanol has been investigated by beam absorption and of the (J, 1, 3?) → (J, 1, 3+) transitions for J = 2, 3, and 6 by beam-maser spectroscopy. The best-fit results for the spin-rotation and spin-spin coupling constants $\text{C}{}_{\mathrm{JK\tau \pm }}{}^{\mathrm{(i)}}$ and $\text{D}{}_{\mathrm{JK\tau \pm }}{}^{\mathrm{(i)}}$, respectively, are in kHz¹: $\text{C}{}_{101}{}^{\mathrm{(1)}}\text{= 2.4(10)}$, $\text{C}{}_{101}{}^{\mathrm{(2)}}\text{= ?0.6(10)}$, $\text{D}{}_{101}{}^{\mathrm{(1)}}\text{= ?13.8(9)}$, $\text{D}{}_{101}{}^{\mathrm{(2)}}\text{= 7.0(9)}$, $\text{C}{}_{\mathrm{213?}}{}^{\mathrm{(1)}}\text{= ?5.0(10)}$, $\text{C}{}_{\mathrm{213?}}{}^{\mathrm{(2)}}\text{= ?5.5(10)}$ and ($\text{C}{}_{\mathrm{J13?}}{}^{\mathrm{(2)}}\text{- C}{}_{\mathrm{J13+}}{}^{\mathrm{(2)}}\text{) = 0.98(9)}$.     

Optical detection of cyclotron resonance of electron and holes in CdTe

Cyclotron resonance of electron and holes have been optically detected at 70 GHz and at 1.8 K in n-type CdTe. The bare effective masses, in unit of the free electron mass, are found to be: $\text{m}{}^1\text{= 0.088 ± 0.004}$, $\text{m}{}^1{}_{\mathrm{lh}}\text{= 0.12 ± 0.01}$, $\text{m}{}^1\text{= 0.60 ± for H // <100>}$, and $\text{m}{}^1{}_{\mathrm{e}}\text{= 0.089 0.004}$, $\text{m}{}^1{}_{\mathrm{lh}}\text{= 0.11 ± 0.01}$, $\text{m}{}^1{}_{\mathrm{hh}}\text{= 0.69 ± 0.02}$ for H // <111>. The Luttinger valence band parameters deduced from these measurements are: γ₁ = 5.3 ± 0.5, γ₂ = 1.7 ± 0.3 and γ₃ = 2.0 ± 0.3, in fair agreement with the calculations of Lawaetz.     

The hypernucleus 12ΛB and the decay process 12ΛB → π− + 3α

The characteristics of the decay sequences ${}^{12}{}_{\mathrm{\Lambda }}\text{B}\text{→ π}{}^{\mathrm{?}}\text{+}{}^{12}\text{C}{}^1\text{,}{}^{12}\text{C}{}^1\text{→ 3α}$ are discussed for the two sharp levels of ¹²C¹ at excitation energies of 12.7 MeV (J_f = 1⁺, T = 0) and 16.11 MeV (J_f = 2⁺, T = 1), which are observed prominently in this decay process. The transition rates for these processes and the angular correlations in the final four-particle state αααπ^? are discussed quantitatively, using the intermediate coupling model for both the ¹²_ΛB and ¹²C¹ systems, as a function of the ¹²_ΛB spin J. Three distinct tests are proposed, which are sensitive to the spin J for ground-state ¹²_ΛB, and which have been used by the European K^? Collaboration to deduce that J = 1 for ¹²_ΛB. The implications of this conclusion for the ΛN and ΛNN interactions are briefly discussed.     

“Forbidden” rotational spectra of symmetric-top molecules: PH3 and PD3

A millimeter-wave spectrometer having a sensitivity of 4 × 10^?10 cm^?1 in the 2-mm region has been constructed for observation of extremely weak millimeter-wave spectra of gases. It has been used to measure J → J, K = 0 ← 3 transitions in PH₃ and J → J, K = 0 ← 3 as well as K = ±1 ← ±4 transitions in PD₃. The B₀ and C₀ spectral constants (in MHz) are: for PH₃, B₀ = 133 480.15 ± 0.12 and C₀ = 117 488.85 ± 0.16; for PD₃, B₀ = 69 471.10 ± 0.03 and C₀ = 58 974.37 ± 0.05. The effective ground-state values obtained for the bond angle and bond length are: for PH₃, $\text{r}{}_0\text{(}\text{A}\text{?}\text{) = 1.420}{}_0$ and $\text{α}{}_0\text{(}{}^{\mathrm{o}}\text{) = 93.34}{}_5$; for PD₃, $\text{r}{}_0\text{(}\text{A}\text{?}\text{) = 1.417}{}_6$ and $\text{α}{}_0\text{(}{}^{\mathrm{o}}\text{) = 93.35}{}_9$. The corresponding zero-point-average values were calculated to be: for PH₃, $\text{r}{}_{\mathrm{z}}\text{(}\text{A}\text{?}\text{) = 1.4269}{}_9\text{± 0.0002}$ and $\text{α}{}_{\mathrm{z}}\text{(}{}^{\mathrm{o}}\text{) = 93.228}{}_7$; for PD₃, $\text{r}{}_{\mathrm{z}}\text{(}\text{A}\text{?}\text{) = 1.4226}{}_5\text{± 0.0001}$ and $\text{α}{}_{\mathrm{z}}\text{(}{}^{\mathrm{o}}\text{) = 93.256}{}_7\text{± 0.004}$. For both species, the equilibrium values are $\text{r}{}_{\mathrm{e}}\text{(}\text{A}\text{?}\text{) = 1.4115}{}_9\text{± 0.0006}$ and $\text{α}{}_{\mathrm{e}}\text{(}{}^{\mathrm{o}}\text{) = 93.32}{}_8\text{± 0.02}$.