Search

A missing-mass search has been made for negatively charged boson resonances B/sup -/ produced in the reaction ..pi../sup -/p ..-->.. B/sup -/p at beam momenta of 40, 100, 200, and 240 GeV. Approximately 600 000 events were included in the final mass spectra. In the mass region 2 < or = M/sub B/ < or = 12.5 GeV no statistically significant enhancements were observed. The 5-standard-deviation upper limit on the production of narrow resonances is of the order of 10 ..mu..b for 2 < or = M/sub B/ < or = 10.5 GeV.

Using the CUSB detector at CESR, we have observed hadronic cascade decays ϒ ″ → ( ϒ or ϒ ′) + ( π + π − or π 0 π 0 ), where ϒ ( ϒ ′) → ( e + e − or μ + μ − ). We derive branching fractions of ϒ ″ → ϒ ′ π + π − . The dipion mass spectrum from ϒ ″ → ϒπ + π − shows no preference for high masses, in strong contrast to the decays ϒ ″ → ϒππ and ψ″ → J ψππ .

The reactionpBe→Λ(1,520)X has been measured at 100 GeV incident momentum in the kinematic range 0.15

An experiment has been performed to search for associated hadronic production of charmed mesons, using a large-aperture forward magnetic spectrometer setup in a π− beam at the CERN SPS. A prompt electron trigger was used to select events containing a pair by charmed particles. D mesons have been identified by reconstruction of hadronic decay modes such as Kπ, Kππ. Data have been taken at 120, 175, and 200 GeV, The D D cross section measured at 175 200 GeV is σ( D D ) = (48 ± 15) μ b with a systematic uncertainty of ±50%. The energy dependence of the cross section is measured to be σ( D D ) [120 GeV )/σ( D D [175/200 GeV ] = 0.62 ± 0.34 .

A search for the S(1936) has been made in the invariant mass spectrum of pp-pairs produced inclusively in proton-beryllium interactions at 100 GeV incident momentum. No enhancement is observed, giving a 3 standard deviation upper limit on the cross section of 220 nb/nucleon for production of a narrow pp state around ≈ 1940 MeV in the x F range 0.18 x F

A narrow enhancement is observed in p p states produced inclusively in proton-proton interactions at 93 GeV. The mass 1940 ± 1 MeV is consistent with that of the S(1936).

Inclusive oo production has been studied in π−-Be interactions for 100 and 175 GeV incident momentum. An upper limit of 72 nb has been set for σ(π − Be → η c (2980) + X ) s BR (η c → oo) at 175 GeV . At both momenta the number of oo events is larger than expected for uncorrelated o pairs. A narrow width enhancement is observed at Moo≈2100 MeV with a 4 standard deviation significance.

The π + π − partial waves are studied up to the F-wave in the mass region from 580 to 1780 MeV/ c 2 at low four-momentum transfer. The study is based on a previous hydrogen target experiment and a more recent polarized target experiment. Using the results of both experiments for 0.01 ⩽ | t | ⩽ 0.20 GeV 2 / c 2 , a partial-wave analysis is performed in each mass bin ( Δm = 40 MeV/ c 2 ) independently. For the first time a model-independent analysis has been possible, which enables us to check the assumptions made in previous studies. In general we find a unique solution determining the exact intensity of each partial wave. The uniqueness of our solution is related to the Barrelet zeros being real in the mass region where their imaginary part were supposed to produce ambiguities. We observe a non-π exchange contribution even in the helicity m = 0 amplitudes.

We report on inclusive K0 production in the region of the upsilon resonances (9.4–10.6 GeV). The K0 yield for the resonances and continuum below the BB threshold is found to be constant at 0.82 ± 0.10 K0 per observed hadronic event. At the ϒ(4S), however, the K0 yield is significantly higher, 1.58 ± 0.35. This increase in K0 production and the differential cross section dσ/dp of kaons are consistent with BB decay of the ϒ(4S) resonance with the bottom quarks subsequently decaying primarily into charmed quarks.

Nearly 200 000 examples of the diffractive process K−p → K−π−π+p at 63 GeV have been obtained using a two magnet spectrometer equipped with Cerenkov counters for secondary particle identification. In addition some 2000 examples of the process K−p → ωK−p have been obtained. The Kππ data have been subjected to partial-wave analysis. The dominant JP = 1+ system couples to K ∗ π , in both S and D waves, ϱK, κπ and eK. The data confirm the existence of two JP = 1+ Q mesons and their masses, widths and branching ratios are given. The ifωK data show that the couplings of the Q mesons to ωK are approximately equal to the couplings to ϱ0K. The two 1+ nonets expected in the quark model are discussed in the light of this and other recent experiments. There is strong evidence for a broad JP = 0− resonance at about 1.46 GeV. At higher masses, structure in the JP = 2− partial waves establishes the existence of at least one JP = 2− L meson.

The reaction pi /sup -/p/sub pol./ to pi /sup -/ pi /sup +/ pi /sup - /p has been measured at 17 GeV/c using a polarized target. The data sample contains about 60000 interactions on polarized protons. The nucleon polarization as a function of momentum transfer is very similar to elastic pi /sup -/p scattering and is nearly independent of the 3 pi mass, except for a possible structure around 1.2 GeV. Using the isobar model, the authors have performed a partial-wave analysis and extracted the 3 pi amplitudes. The generalized 3 pi density matrix elements agree with earlier determinations. Relative phases obtained from density matrix elements agree well with the ones obtained from transversity amplitudes. This proves the validity of the coherence assumption made in the interpretation of unpolarized target results. The results confirm the existence of an A/sub 1/ resonance in the region 1.2-1.3 GeV. (20 refs).

The existence of $P$-wave $b\overline{b}$ bound states ${{\ensuremath{\chi}}_{b}}^{\ensuremath{'}}$ is demonstrated by observation of photons from the transition ${\ensuremath{\Upsilon}}^{\ensuremath{'}\ensuremath{'}}\ensuremath{\rightarrow}\ensuremath{\gamma}+{{\ensuremath{\chi}}_{b}}^{\ensuremath{'}}$ in the inclusive photon spectrum from ${\ensuremath{\Upsilon}}^{\ensuremath{'}\ensuremath{'}}$ decays. The center of gravity of the observed photon energies is 98 MeV and the branching ratio for the transition of the ${\ensuremath{\Upsilon}}^{\ensuremath{'}\ensuremath{'}}$ to the ${{\ensuremath{\chi}}_{b}}^{\ensuremath{'}}$ states is (34\ifmmode\pm\else\textpm\fi{}3)% (statistical).

Results are presented of an experiment studying inclusive ∅-meson production off protons by hadrons of 93 and 63 GeV incident momentum. Evidence is found for an enhanced probability of observing additional strange particles when the final state contains a ∅ meson. This supports the assumption that central production of ∅ mesons proceeds, for a significant part, by the OZI allowed fusion of strange quarks.

Total and differential cross-sections have been measured for the reactions $$\pi ^ - p \to (\pi ^0 ,\eta ,\eta \prime )n$$ . The results agree with those of two experiments carried out in the same energy range, apart from measurements at high |t| for the charge-exchange reaction π− p→π0 n. The latter indicate a deviation from the prediction of a single Regge-pole model with linear trajectories at high incident momentum and high momentum transfer.

We present first results using a photodiode readout for BGO and Nal(Tl) crystals. The measurements indicate that photodiodes might replace photomultiplier tubes in electromagnetic calorimetry. Using commercial photodiodes, a noise equivalent r.m.s. error of 1–2 MeV has been observed. Limitations and possible future improvements are discussed.

We have studied the topologies of hadronic events in e + e - annihilation data taken in the region of the upsilon resonances with the non-magnetic CUSB detectors at CESR. Using a thrust-like variable we compare the decay of ϒ, ϒ′ and ϒPrime; find for ϒ″ a significant excess of high thrust events, which we interpret as evidence for electric dipole transitions.

The A 2 meson is studied in the decay mode ϱ 0 π − using partial wave analyses of 600 000 events from the reaction π − p→ π − π − π + p at 63 and 94 GeV incident momentum. Common production mechanisms are indicated for this resonance and diffractive 1 + and 2 − components.

Electron-positron annihilations intto hadrons were observed in the region of the ϒ (9.46 GeV) and the ϒ′(10.02 GeV) resonances at the storage ring DORIS with the nonmagnetic NaI lead-glass detector. Distributions of sphericity and charged multiplicity were measured. Outside the resonances the data show a clear two-jet structure, while the decays of the resonances are compatible with the predictions of a three-gluon model.

We present a study of leading protons and antiprotons inp-nucleus and $$\bar p$$ -nucleus on Be, Cu, Ag, W, and U targets. The experiment was performed at the CERN-SPS at a beam energy of 120 GeV. For all targets a suppression of secondary antiprotons with respect to protons is observed. The difference between the $$\bar p$$ andp spectra increases with decreasing χ-values and the effect is stronger for heavier nuclei. The features of the data are qualitatively consistent with multiple-collisions modesls. The data are analysed in terms of a dual parton model which gives a satisfactory description of leadingp and $$\bar p$$ spectra.

In a search for charmed particles the reactions ..pi../sup -/+p..-->..p/sub r/+..mu..+X and p+p..-->..p/sub r/+..mu..+X have been studied at beam energies of 200 and 240 GeV, respectively. Measurements of the beam particle and the slow recoil proton, p/sub r/, were used to reconstruct the mass (M) of the ..mu..+X system. Model-dependent upper limits, sensitive to threshold behavior, are presented for the forward production cross section times the muon branching ratio for high-mass states (6

Inclusive ϕ-meson production has been measured for 100 GeV/cK−,\(\bar p\) andp incident on a Be target. Differential cross sectionsdσ/dxF anddσ/dp⊥2 are presented in the interval 0.075

Evidence is given for the existence of a spin-5 boson resonance from the analysis of the reaction π − p→K + K − n at 62 GeV incident momentum. A simplified amplitude analysis with a Breit-Wigner ansatz leads to a mass 2307 ± 6 MeV and a width of 245 ± 20 MeV. The quantum numbers of the resonance are J P = 5 − , C = −1, and very probably I G = 1 + .

In partial wave analyses of the ( π − π − π + ) system, substantial shape changes of the 1 + S ( ϱπ ) intensity as a function of t , and relative phase changes of ≈ 90°, provide compelling evidence for a resonant A 1 of mass ≈ 1280 MeV and width ≈ 300 MeV.

The total cross section fore+e− annihilation into hadrons for center of mass energies from 9.4 to 9.5 GeV has been measured with the nonmagnetic DESY-Heidelberg detector at DORIS. A value ofR=σhad/σµµ=3.8±0.7 for the continuum region around the Υ (9.46) resonance has been determined. The ratioΓ ee Γhad/Γtot of electronic, hadronic and total widths has been reevaluated to be (1.00±0.23) keV for the Υ resonance and (0.37±0.16) keV for the Υ′. In addition, a search for directly produced pohotons from Υ decays of the type Υ→γ+gluon+gluon has been performed. The Υ decay into muon pairs has also been searched for.

The reaction π − p→K + K − n has been studied on a hydrogen target (27 000 events) at 18.4 GeV/ c and on a polarized target (54 000 events) at 17.2 GeV/ c . A combination of results of both experiments allows a partial-wave analysis of the K + K − system between 1.1 and 1.74 GeV mass without any model assumptions. In general our fits yield unique solutions. Using results of our previous analysis of π + π − final states and assuming the dominance of the positive G -parity states in the K + K − system, the branching ratios BR ( K K /ππ) of partial waves into K K and ππ are determined. The S-wave appears to be mainly a broad e (1300) with BR ( K K /ππ) = 0.068 −0.021 +0.017 . The weak P-wave can be described by a tail of the ϱ(770) with BR ( K K /ππ) = 0.081 −0.025 +0.029 . The D-wave is interpreted in terms of a superposition of f(1270) + A 2 (1310) + f′(1515) resonances. The fit yields BR ( K K /ππ) = 0.069 −0.031 +0.023 for the f(1270) and BR( ππ /all) = 0.027 −0.013 +0.071 for the f′(1515). The F-wave shows the g(1690) meson with BR ( K K /ππ) = 0.191 −0.037 +0.040 . All the above values refer to the t bin between 0.01 and 0.20 (GeV/ c ) 2 . Some results are also given for the high- t region.

We present an analysis of theKs0Ks0 system produced in the reaction π−p→Ks0Ks0n at 63 GeV based on ∼700 events in the kinematical region of |t

D ∗± , D ± , D 0 , and D 0 production has been observed in π −Be interactions at 120, 175, and 200 GeV. The dependence of the D cross section on transverse and longitudinal momentum is presented. The ratio of D∗ to D and charged to neutral D production is determined. Leading particle effects in D production are investigated. Relative branching ratios for several D decay modes are evaluated. A limit on D 0 − D 0 mixing is given.

The inclusive reactions h+p→φ+X, (h=π±,,K±,p±), are studied for 0⪅xF⪅0.3 and p⊥ ⩽ 1 GeV at 93 and and 63 GeV incident momentum. Differential cross sections dσ/dp⊥2 anddσ/dxF are presented and are compared with predictions of the naive parton model.

In order to determine the ηNN coupling constant we have measured the two reactions K−p→Λη and K−p→Λπ0 with a magnetic wire chamber spectrometer which contained a gamma counter for the γγ decays of π0 and η. The Λ polarization and the differential cross sections are given. The latter have quite different u dependences. Their ratio is interpreted, in terms of a nucleon-Regge exchange model, as the effect of a small ηNN coupling constant for which we obtain GηNN2 = GπNN2 · (0.26 ± 0.10) as allowed by SU(3). The large value given by Heisenberg's non-linear field theory, GηNN2 = GπNN2 · 0.9, is excluded by this measurement if the characteristic u dependence of the Λπ0 channel is attributed to Nα Regge exchange.

In a sample of 10 000 UPSILON' decays observed with the CUSB nonmagnetic detector at the Cornell Electron Storage Ring we find 23 events consistent with the decay UPSILON'..-->..UPSILON..pi../sup +/..pi../sup -/..-->..e/sup +/e/sup -/..pi../sup +/..pi../sup -/. We derive a branching fraction of 0.20 +- 0.07 for UPSILON'..-->..UPSILON..pi../sup +/..pi../sup -/ and estimates of the partial width for this decay. The invariant mass spectrum of the pion pairs shows a strong preference for large di-pion mass.

We describe the construction and performance of a position sensitive sandwich counter consisting of 27 strip-shaped elements which form a cylinder around a liquid hydrogen target. The lead-scintillator strips are equipped with photomultipliers at both ends; the position of the shower is determined from the time difference of the two photomultiplier signals. Over the sensitive range of the strips (122 cm) the spatial resolution is better than 4.5 cm (fwhm) for electron energies above 250 MeV. The thickness of the counter is 4 radiation lengths of lead, which yields an efficiency above 94% for photon energies above 150 MeV. This detector surrounded a liquid hydrogen target and was used in an experiment with a magnetic spectrometer to detect fast forward particles. From the analysis of this experiment we deduce the probability of detecting a given number of photons in the channel K−p→Λ (forward) π0. The results are found to be in agreement with Monte Carlo predictions.

The CUSB detector at the Cornell electron storage ring has been used to measure R-sigma(e/sup +/e/sup -/..-->..hadrons)/sigma(e/sup +/e/sup -/..--> mu../sup +/..mu../sup -/) in the c.m. energy regions between the UPSILON'' and the UPSILON''', and above the UPSILON''' up to ..sqrt..s = 11.6 GeV, with integrated luminosities of 5000 and 2100 nb/sup -1/, respectively. No narrow resonances are observed, and limits on the leptonic widths are presented. The average value of R increases by 0.31 +- 0.06 across the flavor threshold.

The reaction π − p→ π + π − n has been measured in a high-statistics experiment on a transversely polarized proton target at 17.2 GeV, and unexpectedly large nucleon polarization effects have been observed. Combining the results of this experiment with a measurement on a hydrogen target allows a model-independent partial-wave analysis in terms of the “nucleon transversity” amplitudes. Unique or at most twofold ambiguous solutions are obtained. In particular we find a high lower limit ( ⪆30% ) of the spin non-flip unnatural exchange amplitudes at low | t |. These amplitudes, interpreted as being due to the exchange of an object with the quantum numbers of the A 1 , have been assumed to be absent in previous analyses. In checking the consequences of this finding on the old results, we test the validity of the rank-two assumotions for the density matrix. We find a small but significant deviation, which shows the need for a new phase-shift analysis including the A 1 exchange contribution.

The ϒ′ state has been observed as a narrow resonance at M ( ϒ ′) = 10.02 ± 0.02 GeV in e + e − annihilations, using a NaI and lead-glass detector in the DORIS storage ring at DESY. The ratio Г ee Г had /Г tot of electronic, hadronic, and total widths has been measured to be 0.32 ± 0.13 keV. The parameters of the Г particle have also been determined to be/ M (Г)

The J PC = 2 −+ partial wave intensities and their large phase changes prove the resonant nature of the A 3 meson (mass ≈ 1670 MeV, width ≈ 210 MeV). The decay modes are f 0 π , ϱ 0 π , and ϵ 0 π . Evidence is found for a further 2 − enhancement.

We have used the Columbia University--Stony Brook detector at the Cornell Electron Storage Ring to study the decays of UPSILON(1S) and UPSILON(3S) resonances into a single photon plus a long-lived noninteracting particle. We obtain an upper limit on the branching ratio for UPSILON(1S)..--> gamma..+X, where X is undetected. This upper limit is 3.5 x 10/sup -4/ (90% C.L.) for masses m/sub X/ less than 7 GeV. For the UPSILON(3S) the upper limit is 1.2 x 10/sup -4/ (90% C.L.) for masses less than 4 GeV. Also, the product of the branching ratios of UPSILON..--> gamma..+axion and J/psi..--> gamma..+axion is calculated to be 0.6 x 10/sup -9/, inconsistent with theoretical predictions.

We present single inclusive π±, π0 andK ± spectra in the forward fragmentation region (x>0.2,p T

The reaction π-p → K+K-n has been studied on hydrogen (27 000 events) at 18.4 GeV/c and on a transversely polarized butanol target (54 000 events) at 17.2 GeV/c. A combination of results of both experiments allows to obtain unique solutions for a partial wave analysis of the K+K-system without any model assumptions. This analysis was performed at low four-momentum transfer 0.01 < |t| < 0.2 (GeV/c)2 and in the mass range between 1.10 and 1.74 GeV. Using results of our previous analysis of π+π- final states and assuming the dominance of the positive G-parity states in the K+K- system, the branching ratios BR(KK/ππ) of partial waves S,P,D and F into KK and ππ are determined.

Using the Columbia University-Stony Brook detector we have measured the production of energetic electrons (E>1 GeV) in e/sup +/e/sup -/ annihilations in the center-of-mass energy range 10.4 to 11.4 GeV. We observe an enhanced electron signal at the UPSILON'''(4S) resonance, which we interpret as evidence for the ..beta.. decay of a new flavor of quark, b, bound within a new flavor meson, B. We derive a branching ratio for B..-->..Xe..nu.. of (13.6 +- 2.5 +- 3)%. The observed energy spectrum of the electrons favors the decay b..-->..ce..nu.. over b..-->..uev.

Partial wave analysis is performed on a combined sample of 1,500,000 events with an average polarization of 68%. (AIP)

Diffractive production of the 3π system has been studied at 63 and 94 GeV using a two magnet spectrometer with high, uniform acceptance. The total number of events used in the analysis is ∼600 000. The A2 meson is shown to be diffractively produced. The existence of a resonant component in both the 1+ and 2− enhancements is established and resonance parameters for the corresponding A1 and A3 mesons are given. There are several indications in the data of states which would correspond to radial excitations in the quark model.