A comparison is made of the properties and production mechanisms of the π + ω and K − ω systems produced in the reactions π + p → π + ω p at 4, 5, 8 and 16 GeV/ c and K − p → K − ω p at 10 and 16 GeV/ c . In the π + ω case apeak is observed at 1.23 GeV (the B meson), while the K − ω mass distribution has a threshold enhancement. The cross section of the low mass (<2.0 GeV) π + ω system falls as p lab −2 , while that of the low mass (<2.0 GeV) K − ω system is almost constant with energy, indicating diffractive production of the K − ω system, but not of the πω system. Using a modified version of the Illinois partial-wave analysis program, it is found that the K − ω system is dominantly produced in the J P = 1 + state with small contributions of 0 − and 2 + , mainly by natural parity exchange - as is found for reactions such as K − p → (K − π + π − )p which are predominantly diffractive. For the π + ω system in the B mass region, J P = 1 + states, produced mainly by natural parity exchange are found; the contributions of 0 − P, 1 − P, 2 − P and 2 + D are consistent with zero. The 1 + D state occurs in the π + ω case but not in the K − ω system, nor in the K ππ − system produced in the K − p → K ππ p reaction.
No description provided.
No description provided.
FROM BREIT-WIGNER FIT TO B EVENTS AND CORRECTED FOR UNSEEN OMEGA DECAY MODES.
We report results from a study of π−p→ω0n at 6.0 GeV/c based on 28 000 events from a charged and neutral spectrometer. Background under the ω0 is only 7%, a large improvement over deuterium-bubble-chamber work. Density matrix elements, projected cross sections, and effective trajectories for natural and unnatural exchanges are presented.
No description provided.
No description provided.
No description provided.
A partial wave analysis of the non-diffractively produced ( K ̄ 0 π + π - system has been performed. The system was produced in the reaction K - p→ K ̄ 0 π + π - n at 10 GeV/ c , measured in the CERN Omega spectrometer. Besides the well-known K ∗ (1420) resonance, we find good evidence for the production of Q 2 (1400) and some indication for Q 1 (1290) production in J P =1 + . In addition we clearly observe a bump in the 1800 MeV region, the properties of which are discussed.
BR(<K RHO>/<K* PI>) FOUND TO BE 0.21 +- 0.08 AND 0.9 +- 0.3 FOR K*(1420) AND K*(1780) RESPECTIVELY.
DENSITY MATRIX FOR JP=2+ IN THE REGION 1.3 < M(K PI PI) < 1.55 GEV.
DENSITY MATRIX FOR JP=3- IN THE REGION 1.6 < M(K PI PI) < 1.9 GEV.
The production ofK* resonances has been studied in the reaction\(K^ -p \to \bar K^0 \pi ^ -p\) at 8.25 GeV/c. The data comes from a high statistics bubble chamber experiment (180 events/μb). Masses, widths and production cross-sections have been determined for the first threeK*'s. The contributions from natural and unnatural parity exchange have been obtained for theK*(890) and theK*(1420). A partial wave analysis of theK π system from threshold to 1.9 GeV provides evidence for a 0+ enhancement near 1.4 GeV which could be interpreted as the κ(1350).
FULLY CORRECTED.
No description provided.
PARTIAL CROSS SECTION DUE TO NATURAL AND UNNATURAL PARITY EXCHANGE.
The differential and total corss sections and the decay density matrix elements have been measured for the reactions, γp→ωp and γp→ωΔ+ (1232) in the photon energy range 2.8 to 4.8 GeV. The total cross sections for ωΔ+ (1232) photo-production are found to be slightly larger than those for elastic ω photo-production in this energy range. The data are compared to the predictions of a theoretical model and the contributing exchange mechanics are discussed.
No description provided.
No description provided.
No description provided.
We have investigated the final states K ∗0 (890)Σ, K ∗0 (890)Σ 0 and K ∗0 (890) Y 1 ∗0 (1385) produced in π − p interactions at 3.93 GeV/ c . We present the differential cross sections and spin density matrix elements for the resonances as functions of momentum transfer, as well as the gL and Σ 0 polarizations. The Σ 0 polarization is found to be positive and maximal. An amplitude analysis is performed for the K ∗ Λ and K ∗ Σ 0 reactions, and it is found that one natural parity transversity amplitude is dominant for the latter.
No description provided.
No description provided.
No description provided.
The reactions K + p → K ∗+ (890) p , K + p → K ∗+ (1420) p and K + p → K 0 Δ ++ have been systematically studied for eleven incident momenta between 3.0 and 16.0 GeV/ c . Cross sections, differential cross sections and density matrix elements are presented. For K ∗ (890) production the contributions from natural and unnatural parity exchanges have also been separated into I = 0 and I = 1 components. Effective trajectories have been extracted in the case of natural parity exchange, and also for Δ ++ production.
No description provided.
DATA AT NEIGHBOURING MOMENTA ARE GROUPED TOGETHER. THE RESONANCE PRODUCTION TOTAL CROSS SECTIONS ARE FITTED BY P**-N. THIS TABLE GIVES THE VALUES FOR EACH GROUP OF MOMENTA OF THE FITTED TOTAL CROSS SECTIONS WHICH ARE USED TO NORMALIZE THE DIFFERENTIAL CROSS SECTIONS.
No description provided.
Results are reported of a study of the hypercharge reactions K − p → ωΛ (la), K − p → φΛ (lb), K − p → φ ∑ o (lc), K − p → ϱ o Λ (ld), K − p → ϱ o ∑ o (le), K − p → ϱ − ∑ + (lf) in a 12 events/ub bubble chamber experiment using K − mesons of 4.25 GeV/ c momentum. Total and differential cross sections are presented as well as the density matrix elements of the peripherally produced vector meson and (except for reaction (1f)) the hyperon polarization. For reactions (1a) and (1b) an amplitude analysis is performed. The mass and the width of the ϱ−, φ− and f-meson have been determined.
No description provided.
No description provided.
No description provided.
We present the results of a study of 1173 uniquely identified events of the K 0 π + p final state produced in 10 GeV/ c K + p interactions. This final state is dominated by the quasi two-body processes K + p → K 0 N ∗+ (890 p and K + p → K ∗+ (1420) p . The background is very low and there is little overlapping of resonance bands. We present cross sections, t -distributions and decay angular distributions for the contributing reaction channels. Dips are observed near t = 0 in the differential cross sections for all three processes.
BREIT-WIGNER FIT.
NUMERICAL VALUES TAKEN FROM THE COMPILATION LST7V2 FOX 72B.
No description provided.
We report on A + 2 production in a π + p experiment at 5.45 GeV/ c . The fitted values for the mass and width are given, and the production characteristics are illustrated by the momentum transfer distributions and average density matrix elements. A depletion of events is observed near 1.3 GeV which favours a double pole amplitude or two interfering resonances over a simple Breit-Wigner formula.
No description provided.
PLOT V. T IN FIG. 2(A) NOT COMPILED.
D.M.E'S DETERMINED BY ASSUMING RHO22=0,RHO00=1-2RHO11.
The reaction π − p → A − 2 p at 3.9 GeV/ c incident momentum is studied using data corresponding to the ϱ ° π − , ηπ − and K δ s K − decay modes of the A − 2 . Unnatural parity exchange is found to be important at this energy. The natural parity exchange component of the differential cross section exhibits structure at t ′ ≈ GeV 2 .
CORRECTED FOR ALL A2(1310)- DECAY MODES.
No description provided.
<RHO0 PI-> DATA.
Results of two spark chamber experiments on A 2 − production in the reaction π − p → K − K S 0 (→ π + π − )p at 9.8 and 18.8 GeV are presented. Decay angular distributions and differential cross sections are given, and the energy dependence of the cross section σ [ π − p → A 2 − (→ K − K 0 )p] is compared with results from π − p → A 2 − (→ 3 π )p.
FITS WITH CONSTANT BACKGROUNDS. A TWO-PARAMETER LINEAR BACKGROUND GIVES MUCH LARGER ERRORS.
INTEGRATED OVER M(K AK) = 1.20 TO 1.42 GEV.
No description provided.
Transversity amplitudes and spin density matrix elements are determined for the process K − p → (π + π − ) s-wave ϵ 0 (1385). Predictions of the additive quark model and of duality diagrams are tested and found consistent with the data; this is the first information about the applicability of these models to processes where a scalar object is produced at the mesonic vertex.
No description provided.
We have investigated the ρ-meson production mechanism in the three reactions π±p→ρ±p and π−p→ρ0n at 3.9 GeV/c (s=8.2 GeV2) using the prism-plot technique. Differential cross sections at all momentum transfers are presented. A significant backward peak has been found in all three reactions. The differential cross sections for these backward peaks are given and are compared with the equivalent pion elastic and charge-exchange cross sections in the backward direction. Using a linear combination of the three differential cross sections we have isolated the I=0 exchange contribution in the forward direction. This differential cross section has a zero at −t=0.45 (GeV/c)2 and is fitted by the dual absorptive model of Harari with an interaction radius of ∼ 1.2 F. The total I=0 cross section is calculated and compared with similarly determined cross sections at higher momenta. An analysis of the properties of the other possible spin-parity exchanges is also presented.
SLOPE FITTED OVER 0.05 < -T < 0.3 GEV**2.
No description provided.
No description provided.
The ωπ − mass spectrum, in the reaction π −p → ωπ − pat 11.2 GeV/ c , shows the production of the B − meson with a cross section of 27 ± 5 μb as well as a clear enhancement around 1670 MeV. In the differential cross section for B − production, there is a strong forward peak and a change of slope at t ' t 0.2 GeV 2 .
No description provided.
ABS(D-WAVE/S-WAVE) = 0.4 +- 0.1 FOR B DECAY.
A detailed analysis is presented of the reactions pp→pp,pp→ppπ0 and pp→pπ+n. The production cross sections are found to be 11.47 ± 0.33 mb, 2.54 ± 0.16 mb, and 5.73 ± 0.35 mb, respectively. The t dependence of elastic scattering can be described by the form e7.9t over the range 0.05<−t<0.50 GeV2. The single-particle distributions for the single-pion production processes are presented. Further detailed analyses are presented which demonstrate that pion-exchange phenomenology, both elementary and Reggeized, can account for the gross features of the peripheral pp→pπ+n data for M(pπ+)<2.4 GeV. Isospin-12 isobars are produced by some other processes in the channel pp→pN*+, especially when the invariant mass of the pion with the unrelated proton is large. We discuss the properties of these isobars.
No description provided.
FITTED OVER 0.05 < -T < 0.5 GEV**2.
No description provided.
The reactions π − p → p π − and π − p → p ϱ − ( ϱ − → π − π 0 ) at 10 GeV/ c with the proton in the forward direction in the c.m.s. are discussed on the basis of 953 elastic scattering events and 2240 events of the reaction π − p → p π − π 0 . The total backward cross sections are 0.52±0.10 and 1.52±0.28 μ b, respectively. In both cases the production mechanism is compatible with the dominance of the baryonic Δ δ Regge trajectory exchange. The ϱ − decay angular distributions are studied in the u -channel helicity frame and the spin density matrix elements are presented as functions of u .
No description provided.
DATA FROM PRIV COMM WITH B. GHIDINI.
DATA FROM PRIV COMM WITH B. GHIDINI.
We have studied the backward production of ω 0 mesons in the u -channel I u = 1 2 exchange reaction π − p → N 0 (1680) ω 0 at 9 GeV/ c and 12 GeV/ c incident momenta. The data come from an experiment performed at the CERN Omega Spectrometer using a fast proton trigger device. The backward production of the η 0 meson has also been observed and the coupling constant ratio g η NN / g π NN has been estimated.
No description provided.
No description provided.
JACKSON FRAME (U-CHANNEL HELICITY SYSTEM).
We have analysed about 85 000 fast Λ 0 events, obtained in a fast proton triggered experiment performed at the CERN-Ω spectrometer at 9 and 12 GeV/ c incident π − beam. Nearly 2500 Λ 0 K + π − events have been isolated. We find strong production of quasi-two-body processes Λ 0 K ∗0 and ∑ ∗− K + consistent with u -channel hyperon exchange. Results on Λ 0 polarization, K ∗0 decay parameters and differential cross sections are given for Λ 0 K ∗0 (892) and Λ 0 K ∗0 (1430) final states. A comparison is made with the associated backward Λ 0 (1520) K ∗0 production seen in the four-prong reaction π − p→pK − K + π − obtained in the same experiment.
No description provided.
No description provided.
EXPONENTIAL FIT TO DN/DU.
A measurement of backward photoproduction of charged pion pairs on protons is reported. The pion pair mass spectrum shows strong ϱ ° and f production. Data are presented on the u and s dependence for ϱ O and f, together with the decay polarisation for the ϱ O .
No description provided.
No description provided.
AVERAGED OVER U RANGE OF EXPERIMENT. NO EVIDENCE FOR ANY LARGE S-WAVE CONTRIBUTION TO THE PI PI SYSTEM IN THE RHO0 MASS REGION (RHO(0S) < -0.03 +- 0.13). U CHANNEL FRAME: Z AXIS IN INCIDENT PROTON DIRECTION IN THE DIPION REST FRAME.
We have analyzed backward meson production in the reaction π − p → p f π + π − π − at 9 GeV/ c and 12 GeV/ c incident π − momenta, from an experiment performed at the CERN Ω Spectrometer using a fast proton (p f ) trigger device. We find strong production of quasi-two-body processes N ∗ ϱ and N ∗ f with a production mechanism consistent with u -channel nucleon exchange. At a lower level, we observe N ∗ π processes with a 3-body baryon decay through Δ(1232)π. In the (3π) − system, we find evidence for A 1 − and clear A 2 − backward production with similar cross sections (≈0.5 μb).
No description provided.
U-HELICITY JACKSON FRAME.
U-HELICITY JACKSON FRAME.
We have studied backward baryon and meson production in π−p→pπ+π−π− at 8.0 GeV/c using a streamer chamber triggered by the detection of a fast forward proton. Our data sample (1227 events) displays prominent N*ρ and N*f quasi-two-body production. These states are investigated with regard to the peripheral nature of the production mechanism and sequential decay of the excited baryon and meson systems. The quasi-two-body production of N*ρ and N*f intermediate states is consistent with u-channel proton exchange as the dominant production mechanism. In the π+π−π− mass distribution we observe a 3- to 4- standard-deviation enhancement at M3π=1897±17 MeV/c2 with full width at half maximum = 110 ± 82 MeV/c2, but find no but find no evidence for backward A1 or A2 production. We observe Δ++(1232) production in the pπ+ effective mass distribution.
THESE VALUES ASSUME ONLY RHO(11) IS NON-ZERO. VALUES FOR OTHER RHO(MM) ARE QUOTED IN PAPER. SIG ERRORS INCLUDE OVER-ALL NORMALIZATION UNCERTAINTY, BUT NO BACKGROUND CORRECTIONS HAVE BEEN MADE.
STATISTICAL ERRORS ONLY, NO BACKGROUND CORRECTION.
STATISTICAL ERRORS ONLY, NO BACKGROUND CORRECTION.
We have studied backward meson and baryon production in π−p→nπ+π− at 8 GeV/c using a streamer chamber triggered by the detection of the interaction of the neutron in thick-plate optical spark chambers. Our data sample of 866 events is dominated by the quasi-two-body final states Δ−(1232)π+, nρ0, and nf0. We study the differential and total backward cross sections for these states and the decay angular distributions of the resonances. The results for the Δ− and ρ0 indicate that both nucleon and Δ exchange in the u channel are important in their production, while f0 production is, as expected, consistent with nucleon exchange.
No description provided.
BACKWARD DIP.
No description provided.
None
SIG(C=BACKWARD) = SIG(-UP<1 GEV**2)/(1-EXP(-SLOPE)). UP DISTRIBUTION OF EVENTS HAS A PERFECT EXPONENTIAL SHAPE.
Final states produced by charged baryon exchange in π − p interactions at 12 GeV/ c laboratory momentum have been studied. Forward neutrons with momenta determined by a calorimeter to be greater than 8.5 ± 1.4 GeV/ c triggered the SLAC 40-inch hydrogen bubble chamber which operated at a 10 Hz expansion rate. We report data on the reactions π − p→n π − π + , π − p→n π − π + π 0 , and π − p→n π − π − π + π + . In π − n π − p→n π + , production of ϱ and f mesons is observed. Differential cross sections are derived and compared with data at lower incident momentum and with theoretical models. In π − p→n π − π + π 0 , ω production is observed with a differential cross section having a deep near u ′= 0.2 (GeV/ c ) 2 . In π − p→n π − π − π + π + , Δ − , ϱ and f production is observed . The observed mass distributions appear to indicate the production of wide resonaces decaying into ϱππ. Some evidence for ϱ-ω interference is also observed.
No description provided.
No description provided.
CORRECTED FOR BACKGROUND.
We present cross sections and density-matrix elements from a high-statistics study of the reactions π−p→ρ0n, K−p→K¯*0(890)n, and K+n→K*0(890)p, at 3, 4, and 6 GeV/c and four-momentum transfer squared to the recoil nucleon −t<~0.9 GeV2. The experiment was carried out at the Argonne Zero Gradient Synchrotron using the effective-mass spectrometer. In the same experiment, we have measured the ρ−ω interference cross sections by comparison of the two reactions π−p→π−π+n and π+n→π+π−p, to which the interference terms contribute with opposite signs. We examine the systematics of ρ0 production: In the s channel we find little shrinkage with energy of the helicity-0 cross sections, which are presumably dominated by π exchange; the helicity-1 cross sections exhibit considerable shrinkage for unnatural-parity exchange, and antishrinkage for natural-parity exchange. The K*0 and K¯*0 production observables exhibit significant differences, especially in the helicity-1 states. These differences are due to interference between even- and odd-G-parity exchange amplitudes and they are related by SU(3) symmetry to ρ−ω interference effects and to the ρ0 and ω production observables. It is shown that exchange-degeneracy-breaking effects satisfy SU(3) symmetry and can be explained qualitatively in the frame-work of SU(3)-symmetric, strongly absorbed Regge-pole models. The results of our amplitude analysis are compared with previous phenomenological analyses and model predictions.
No description provided.
No description provided.
No description provided.
Cross sections are presented for all final states without strange-particle production. Contributions to single-pion production are found from (i) Δ(1238)π, (ii) ρ+p, (iii) nucleon diffractive dissociation into Nπ, (iv) N*(1688)π+, and (v) "phase space." Processes (i), (ii), and (iii) are studied in some detail taking into account overlaps between the various subchannels.
No description provided.
'JM'.
'JM'. USING DATA WITH 1.12 < M(P PI+) < 1.32 GEV AND COS(P PI DECAY ANGLE IN JACKSON FRAME) < 0.
From the reaction π−n→pπ−π−π0 at 9.140 GeV/c the Δ0ϱ− reaction has been selected. The upper limit in the cross-section ofμb
A SMALL CORRECTION FOR THE DEL0 TAIL IS NOT PERFORMED.
No description provided.
No description provided.
We have studied ω photoproduction using 7.5- to 10.5-GeV tagged photons. Cross sections from hydrogen lie 22% below the bubble chamber results of Ballam et al., but have a similar slope. Density matrices indicate approximate s-channel helicity conservation. The proton-neutron cross-section difference is midway between zero and the value suggested by the γp−γn total-cross-section difference. Fits to the cross sections for D, Be, and Cu and those for Be, C, Al, Cu, and Pb from a previous experiment yield σωN=25.4±2.7 mb and γω24π=7.6±1.2.
No description provided.
FORWARD CROSS SECTION IS 366 +- 49 MUB/GEV**2 AND SLOPE IS 47.1 +- 8.0 GEV**-2.
The differential cross section of the reaction ( γ p → p φ ) has been measured in the t range 0 ⩽ t ⩽ 0.4 GeV 2 and for photon energies from 3.0 to 6.7 GeV. In particular for the small t region the measurement accuracy was better than 10%. We obtained for the slope parameter B in an exponential parametrization of the differential cross section d σ /d t = A e − Bt values of B ⋍ 6 ± 0.5 GeV −2 which are significantly larger than the slopes obtained by most other experiments at higher t values. This indicates a t dependence of B particularly in the small t region.
No description provided.
No description provided.
No description provided.
Elastic K+p scattering at a beam momentum of 4.27 GeV/c is studied and compared with elastic K−p scattering in order to extract the imaginary part of the non-Pomeranchukon-exchange amplitude. The single-pion-production cross sections are presented as well as production cross sections and resonance parameters for the Δ(1236), the K*+(890), and the K*+(1420). Production and decay distributions for the Δ++(1236) and the K*+(890) are presented and compared with the absorptive particle-exchange model and with Regge-pole-exchange models.
No description provided.
BREIT-WIGNERS PLUS PHASE SPACE TO DETERMINE RESONANCE PRODUCTION CROSS SECTIONS.
No description provided.
We present results of an analysis of two-prong events for elastic scattering and single-pion production in K−p interactions at 5.5 GeVc. The resonance parameters for the charged and neutral K*(890) and K*(1420) are determined and the observed production and decay properties of the charged and neutral K*(890) are compared with the theoretical predictions of an absorptive one-particle-exchange model and a Regge model. The K*(1420) differential cross section and density-matrix elements are presented and the question of whether more than one resonance exists in this mass range is considered. A search for resonance effects at Kπ mass beyond 1500 MeV is made. In particular, the recently reported state at 1800 MeV is discussed. A B5-model analysis of the reaction K−p→K¯0π−p is also presented.
NORMALIZED TO SIG(K- P --> ANYTHING) OF 24.3 +- 0.8 MB.
FORWARD CROSS SECTION OPTICAL POINT FROM TWO PARAMETER EXPONENTIAL FIT OVER 0.12 < -T < 0.68 GEV**2.
No description provided.
A partial-wave analysis has been performed on the (K − π − π + ) system produced in the reaction K − p → K − π − π + p at 10 and 16 GeV/ c . In the Q mass region it is found that the two dominant states, K ∗ π and Kπ, both in 1 + S wave, are produced with different polarisations, helicity being approximately conserved in the t -channel for K ∗ π and in the s -channel for Kπ. This is in contradiction with the assumption that the amplitude can be factorised into “production” and “decay” parts, and hence that the two amplitudes are fully coherent. The phase variation of the two states do not indicate simple resonance behaviour. It is concluded that the Q-mass enhancement is composite.
No description provided.
We have performed a partial-wave analysis of the mainly diffractively produced low-mass (K ππ ) system in the reactions K − p → K − π + π − p and K − p → K 0 π − π 0 p at 10, 14 and 16 GeV /c . We find that the dominant 1 + S ( K ∗ π ) state has possibly a two-peak structure (around 1.27 and 1.37 GeV). In contrast the 1 + S(K ϱ ) state shows one narrow peak near thershold (around 1.27 GeV). These states are found to be of different origin. The results favour the interpretation of the 1 + S(K ϱ ) as a 1 + resonance below the (K ϱ ) threshold. The t ′ pp dependence is found to be different for the 1 + and 0 − states.
No description provided.
We have studied ϱ − production at 8 GeV / c . The data cannot be explained by one-pion-exchange with absorption and we conclude that vector exchange contributes. This contrasts with ϱ o production at this energy and ϱ − production at lower energy.
No description provided.
The production of the f 0 (1270) has been studied in the reaction π − p → π + π − n at 12 and 15 GeV/ c in the momentum transfer range 0.02 to 0.80 GeV 2 . Differential and total cross sections for the reaction π − p → f 0 n have been determined. The f 0 decay density matrix elements have been evaluated requiring all the matrix eigenvalues to be non-negative. The relative unnatural and natural parity exchange contributions to the f 0 production have been studied. The results are compared with a Regge exchange model formulated in terms of the pion and A 2 exchanges including cut contributions.
No description provided.
No description provided.
No description provided.
This report concerns itself with the study of four- or five-body final states produced by the interaction of 4.48-GeV/c K− mesons on neutrons. The data result from a 372 000-picture exposure in the Argonne National Laboratory 30-in. deuterium-filled bubble chamber. The reactions studied include (1) K−n→Λπ+π−π−, (2) K−n→Σ0π+π−π−, (3) K−n→Λπ+π−π−π0, (4) K−n→Λπ+π−π−MM, (5) K−n→Λπ−K+K−, and (6) K−n→Λπ−KL0KS0, where all the Λ particles decayed visibly. Evidence is presented for the existence of the Σ(1640) whose mass and width are 1642 ± 12 MeV/c2 and 55 ± 24 MeV/c2, respectively. The branching ratios are found to be consistent with an octet assignment. The A2 data are presented and are compatible with JPC=2++. In addition, the productions of ρ0, ω, and φ0 are discussed in conjunction with simultaneous Σ−(1385) production and the results are compared with quark-model predictions.
No description provided.
No description provided.
We have measured 618 K + p → π + K S 0 p events at 12.7 GeV/ c incident lab momentum, mass range 790 ⩽ m π + K s 0 ⩽ 990 MeV and t range 0.01 ⩽ − t ⩽ 0.60 (GeV/ c ) 2 . The π + K S 0 mass spectrum is dominated by the K ∗+ (892) resonance and a Breit-Wigner fit yields a mass m = 893.5 ± 1.1 MeV and a width Γ = 33.2 ± 4.1 MeV which is much narrower than measured hitherto. The t distribution of K ∗+ (892) events shows a dip in the forward direction and an exponential fall off thereafter, consistent with dominance of helicity flip amplitudes. The spin density matrix is almost saturated by ρ 11 and ρ 1−1 which are very close to their maximum allowed value of 1 2 throughout the measured t range except in the very forward direction where ρ 00 and Re ρ 10 deviate from zero. Natural parity exchanges, therefore, dominate with unnatural parity exchanges being restricted to a small region in the forward direction. A Regge pole analysis of the differential cross sections of the present measurement in conjunction with previously measured total cross sections supports the f-coupled-pomeron hypothesis.
SUBTRACTED BACKGROUND IS PHASE SPACE.
SUBTRACTED BACKGROUND IS AN INCOHERENT S-WAVE WITH EXPONENTIAL T-DEPENDENCE WITH SLOPE OF 6 GEV**-2.
Axis error includes +- 15/15 contribution.
Approximately 350 A 2 + events have been observed in the reaction π + p → K + K S 0 p ( K S 0 → π + π − ) at an incident π + laboratory momentum of 12.7 GeV/ c . The events are distributed over a range of four-momentum transfer squared 0.01 ⩽ − t ⩽ 0.60 (GeV/ c ) 2 and K + K S 0 mass 1.11 ⩽ m K + K S 0 ⩽ 1.51 GeV . A Breit-Wigner fit to the mass spectrum yields a mass for the A 2 + , m A 2 + = 1.324 ± 0.005 GeV, and a width Γ 0 = 0.110 ± 0.018 GeV. We find a cross section σ ( π + p → A 2 + p) = 1.71 ± 0.30 μb referring to the above-mentioned mass and t range and A 2 + → K + K S O with K S 0 → π + π − . The spin-space density matrix in the Gottfried-Jackson frame is practically saturated by ϱ 11 ⋍ ϱ 1−1 = 1 2 suggesting natural parity exchanges only. There is a forward dip in the angular distribution consistent with dominance of s -channel net helicity flip amplitudes and ϱ and f Regge exchanges suffice to describe adequately our differential cross sections.
SUBTRACTED BACKGROUND IS PHASE SPACE. FITTED D(SIG)/DT SLOPE IS 9.5 +- 0.9 GEV**-2.
SUBTRACTED BACKGROUND IS AN S-WAVE WITH SLOPE OF 8 GEV**-2. FITTED D(SIG)/DT SLOPE IS 6.9 +- 0.6 GEV**-2.
FROM D(SIG)/DT. ERROR INCLUDES 15 PCT SCALE ERROR ADDED QUADRATICALLY.
The s and t dependence of φ (1019) photoproduction has been investigated in the incident photon energy range 2.8 to to 4.8 GeV. Differential cross-sections and density matrix elements are presented for a t range extending from t min out to −1.3 (GeV/ c ) 2 . The results are discussed in terms discussed in terms of an effective Regge trajectory in the t -channel.
DIFFERENTIAL CROSS SECTIONS AVERAGED OVER TWO RANGES OF INCIDENT PHOTON ENERGY.
VARIATION OF SMALL -T DIFFERENTIAL CROSS SECTION WITH PHOTON ENERGY.
INTERCEPT AND SLOPE FROM FITS TO D(SIG)/DT AT SMALL -T.
None
No description provided.
No description provided.
We report measurements of inelastic photoproduction of ω and ρ± mesons from hydrogen and deuterium at incident photon energies in the range 7.5-10.5 GeV. For ωΔ and ρ−Δ++ production, differential cross sections dσdt′ and spin density matrices are presented. For higher missing masses the cross sections dσdMX2 and invariant structure functions F(x) are also given. The data are compared to a one-pion-exchange model. We conclude that pion exchange is dominant for inelastic ω photoproduction, but unimportant for ρ±.
CROSS SECTION PER NUCLEON FOR COMBINED HYDROGEN AND DEUTERIUM DATA ALLOWING FOR A GLAUBER CORRECTION FACTOR OF 0.88 FOR THE DEUTERIUM CROSS SECTIONS.
HYDROGEN AND DEUTERIUM DATA COMBINED BY AVERAGING.
OBTAINED BY EXTRAPOLATING A FIT TO D(SIG)/DT OVER -T = 0 TO 0.52 GEV**2.
The reactions of positive pions with protons yielding four charged particles and one or more neutrals have been studied, especially the reaction π+p→Δ++ω0→pπ+π+π−π0. The results presented in this paper were obtained from a 100 000-picture exposure of the Argonne-MURA 30-in. liquid hydrogen bubble chamber, with a beam of incident pions of 4.09−GeVc momentum. Comparisons have been made with corresponding results of other experiments at various incident beam momenta, and with the predictions of some theoretical models of the π+p interaction.
INCLUDING CORRECTIONS FOR BACKGROUND.
No description provided.
No description provided.
An experiment using optical spark chambers and a neutron time-of-flight hodoscope has been performed at the Argonne National Laboratory on the reaction π−p→ω0n. The differential cross section and the experimentally accessible density-matrix elements were determined in the momentum transfer interval 0.05≤|t|≤1.0 (GeV/c)2 at each of three incident pion momenta 3.65, 4.50, and 5.50 GeV/c. Our results show the following general features: (1) a dip in the forward differential cross section for |t|≤0.2 (GeV/c)2, (2) a slope at larger momentum transfers which increases as the incident pion momentum increases, and (3) no dips in either dσdt or ρ11+ρ1−1, the natural-parity exchange combination, at |t|=0.6 (GeV/c)2.
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Data are presented on the production of the KN π final states in K + p interactions at 7.3 GeV/ c . The energy dependence of the KN π final state cross sections, the effective-mass distributions, and the spectra of c.m. longitudinal momenta are given, and features of these data are compared with predictions of the generalized Veneziano (GV) model. Furthermore, we present the momentum transfer and decay angular distributions for K ∗ (890), K ∗ (1420) and Δ (1236) production within the KN π final states and discuss these quasi-two-body reactions in terms of the GV model.
BREIT-WIGNER RESONANCE FITS WITH BACKGROUND CONTRIBUTION.
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Reactions K + n → (K π )N have been studied using data from the CERN 2 m deuterium bubble chamber obtained with incident K + of 8.25 GeV/ c . There is an abundant production of K ∗ (892) and K ∗ (1420). The reaction and K ∗ resonance production cross sections are presented. K ∗ production and decay angular distributions are analyzed. Charge-exchange reactions are dominated by unnatural parity exchange and the non-charge-exchange reaction by natural parity exchange. The K ∗ 0 (892) data are in good agreement with the predictions of an OPE absorption model. A broad enhancement around 1850 MeV could be interpreted as a signal for the K ∗ 0 (1780).
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FIT TO D(SIG)/DT = A*EXP(SLOPE*TP) FOR K* EVENTS WITH -TP < 0.24 GEV**2.
Differential cross sections and density matrix elements are presented for K ∗− (890) and K ∗− (1400) produced in the reaction K − p→K O π − p at 3.95 GeV/ c . The cross sections are decomposed into contributions due to different exchange mechanisms.
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K ∗0 (890) production in the hyperchange exchange reaction π − p → K ∗0 (890) Λ 0 Σ 0 at 10 GeV/ c (28 448 events) is discussed. An amplitude analysis in the t ′ range up to 1 GeV 2 shows that the production mechanism is dominated by natural parity exchange (∼84%). Comparisons are made with predictions from a Regge model and a quark model.
DENSITY MATRIX ELEMENTS IN THE GOTTFRIED-JACKSON SYSTEM ALLOWING FOR COHERENT S-WAVE BACKGROUND TO P-WAVE BREIT-WIGNER K*(892)0 RESONANCE.
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Baryon resonance production in quasi-two-body reactions has been studied for the channels K + p→K°p π + , K + n π + and K + p π ° at beam momenta of 2.53, 2.76 and 3.20 GeV/ c . The production cross sections, four-momentum transfer distributions and density matrix elements are given for the Δ(1236), N ∗ (1400), N ∗ (1500) and N ∗ (1680) states. The reaction K + p→K° Δ ++ (1236) is compared to the line reversed reaction K − n → K °Δ − and the charge-exchange SU(3) sum rule for pseudo-scalar meson plus Δ(1236) is tested.
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The results presented in this paper are obtained from an analysis of bubble-chamber pictures of K−d interactions at an incident K− momentum of 5.5 GeV/c. Generally, the quasitwo-body final states are produced peripherally, with a small backward peak occurring in some of the final states. The final states Σ−ω, Σ−ρ0, and Σ−φ appear to be produced primarily by vector-meson exchange. In the final state Λ(1520)π− the decay distributions of the Λ(1520) hyperon are found to be consistent with a vector-exchagne production process with M2 coupling at the nucleon vertex. The predictions of the independent-quark model and of other symmetry schemes, namely that the forward cross sections for Σ−ρ0, Σ−ω, Σ−φ production be in the ratios 1: 1: 2, are not inconsistent with our experimental values.
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FRACTIONAL FORWARD HYPERON CROSS SECTION AFTER BACKGROUND SUBTRACTION.
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