L. Lyons

A measurement of inclusive π0 production at large pT from p-p collisions at the CERN ISR

Abstract The inclusive cross section for larger p T π 0 production near 90° in p-p collisions at the CERN ISR is presented for centre-of-mass energies 30.7, 53.1 and 62.4 GeV. The data are inconsistent with scaling of the form p T − n F ( x T ), with constant n or with n allowed to depend on x T = 2p T / s . For s = 53.1 and 62.4 GeV , the value of n found for 3.5 p T c is n = 8.0 ± 0.5, in agreement with previous experiments. However, for 7.5 p T c the value becomes n = 5.1 ± 0.4.

A Measurement of Inclusive pi0 Production at Large p(T) from p p Collisions at the CERN ISR

Abstract The inclusive cross section for larger p T π 0 production near 90° in p-p collisions at the CERN ISR is presented for centre-of-mass energies 30.7, 53.1 and 62.4 GeV. The data are inconsistent with scaling of the form p T − n F ( x T ), with constant n or with n allowed to depend on x T = 2p T / s . For s = 53.1 and 62.4 GeV , the value of n found for 3.5 p T c is n = 8.0 ± 0.5, in agreement with previous experiments. However, for 7.5 p T c the value becomes n = 5.1 ± 0.4.

Non-strange vector meson production in K−p interactions at 4.2 GeV/c

Abstract The vector meson production, hypercharge exchange reactions K − p → ( φ , ω , ϱ ) Λ and ( φ , ϱ ) Σ 0 are studied at 4.2 GeV/ c incident momentum. The data come from a high statistics bubble chamber experiment with a sensitivity of ∼ 120 events/μb. Total and differential cross sections are presented. The vector meson density matrix elements and hyperon polarization are investigated as functions of momentum transfer. Amplitude analyses are performed for all five reactions. The results are compared with duality and quark model predictions, as well as used to test current ideas in two-body phenomenology.

Charm D-meson production in 360 GeV/cπ−p interactions; Evidence for leading quarks

Abstract Charm D-meson production in 360 GeV π−p interactions has been studied using the high-resolution hydrogen bubble chamber LEBC and the European Hybrid Spectrometer. The data show evidence for leading quark effects both in the number of D-meson types and in the Feynman x distributions. The production cross section is of the form d 2 δ d x d p T 2 ∞(1-x) n exp (-ap T 2 ) with n = 2.8±0.8 and a = 1.1±0.3 (GeV/c)−2. The x distribution is, however, compatible with the presence of both central (n = 6) and leading (n = 1) D / D production. The fraction of D-messons in the leading component is estimated to be ≈30%. The rapidity gap between members of reconstructed charm pairs is small compared to the available rapidity range. The inclusive cross section for single D-messons in the forward direction is: δ(D/ D )=(40 8 +15 )μ b ( for x>0) .

A Study of Final States Containing High-pT πo's at the CERN ISR

A large solid-angle apparatus consisting of a superconducting solenoid magnet, cylindrical drift chambers, and two arrays of lead-glass counters is used to examine particles associated with a high transverse momentum trigger in pp interactions at the CERN ISR. The trigger is given by energy deposition in the lead-glass arrays centred at 90°. Results on particle correlations and on jets are presented for interactions at √s = 62.4 GeV and in the trigger transverse momentum range 3 < pT < 11 GeV/c.

Fitting K−p → K0 π−p with a generalized Veneziano model

Abstract Fits are made to new K − p → K 0 π − p data at 3.3 GeV/ c with a generalized Veneziano model that includes both vector and pseudoscalar exchanges. Tests of the exchange degeneracy properties of the Regge trajectories show that the model prefers exchange degeneracy of the K ∗ (890) and non-exchange degeneracy of the Δ(1238). Several defects in the model are noted.

FITTING K

Abstract Fits are made to new K − p → K 0 π − p data at 3.3 GeV/ c with a generalized Veneziano model that includes both vector and pseudoscalar exchanges. Tests of the exchange degeneracy properties of the Regge trajectories show that the model prefers exchange degeneracy of the K ∗ (890) and non-exchange degeneracy of the Δ(1238). Several defects in the model are noted.

sup -

Abstract An enhancement is observed in Λ 0 π + effective mass in the reaction K − + p → Λ 0 + π + + π − at 6 GeV/ c . The lack of any large enhancements in other final states, as well as the shape and position of the peak, suggest that it is due to the new hyperon resonance, the Y 1 ∗ (1700), since it cannot be explained in terms of the known Y 1 ∗ (1660) and Y 1 ∗ (1765).

p

Abstract π − ω interference is studied in the reactions K − p → π + π − (Λ 0 , ϵ) at 4.2 GeV/ c using data from a high statistics experiments in the CERN 2m HBC. The phenomenon is analysed in terms of the conventional formalism as well as in terms of a new model for π − ω interference proposed by Earles and Srivastava. Satisfactory agreement with the data is found for both models. The rate of ω → 2π obtained in the latter model is in agreement with the VMD (Vector Meson Dominance) prediction for ω → γ → ϱ → 2π.

Yields

Abstract Various three-body final states produced in 6 GeV/ c K − p interactions show peripheral features. These are examined in some detail, and it is found that a double peripheral mechanism is consistent with the data. For each reaction when interpreted in this way the most important double peripheral process is one in which the final state pion is produced at the central vertex. Two-dimensional transfer distributions are analysed; it is found that the strongest dependence on momentum transfer occurs when the relevant initial and final state particles are identical.