Anne Kernan

Further evidence for production of electrons with small transverse momenta in pp collisions

A new measurement of prompt lepton production at small transverse momenta in pp collisions at the ISR, for s = 53 GeV, is presented. The cπ ratio, which is about 10−4 for pT > 1 GeV/c, rises rapidly as pT goes to smaller values, confirming our original results. The data are consistent with equality between the numbers of e+ and e− produced in each transverse momentum interval.

Search for D0-meson production in p-p interactions at a centre-of-mass energy of 53 GeV

Abstract A search for D(1.87) mesons produced at x ∼ 0.1 at the CERN ISR gave a null result. Cross-section upper limits of 9 μb and 8 μb at the 95% confidence level were measured for the processes p + p → D 0 + X, D 0 → K − + π + , and p + p → D 0 + X , D 0 → K + + π − , respectively. Producton of f 0 (1270) was observed with a cross-section of 1.9 ± 0.4 mb.

Primary cosmic ray α-particles — II

SummaryThe primary cosmic-rayα-particle energy spectrum has been investigated, using photographic emulsions flown from Minneapolis on July 30th, 1957. The total flux observed was (151±9)particles/cm2 sr s. The differential energy spectrum shows a broad maximum between 400 and 600 MeV/nucleon, and appears different in shape from the spectrum observed at solar minimum. No particles were observed to have kinetic energies below 200 MeV/nucleon, but a substantial flux was observed between 200 and 300 MeV/nucleon. From the centered dipole approximation to the geomagnetic field, one would expect a cut-off energy at this latitude of 292 MeV/nucleon. The results presented here are in disagreement with this figure, but do not allow a choice to be made between cut-off energies predicted from other models.RiassuntoÈ stato analizzato lo spettro di energia delle particelleα dei raggi cosmici pri mari usando emulsioni fotografiche lanciate da Minneapolis il 30 Luglio 1953. Il flusso totale osservato fu di (151±9) particelle/m2 sr s. Lo spettro differenziale dell’energia presenta un largo massimo fra 400 e 600 MeV/nucleone, ed appare di forma diversa da quello osservato nei minimi solari. Non si osservarono particelle aventi energie cinetiche inferiori a 200 MeV/nucleone, ma si osserva un flusso notevole fra 200 e 300 MeV/nucleone. Dalla approssimazione al campo geomagnetico con dipolo centrato, ci si aspetterebbe a quella latitudine una energia di cut-off di 292 MeV/nucleone. I risultati qui presentati, sono in disaccordo con questo valore, ma non permettono di fare una scelta fra le energie di cut-off predette con altri modelli.

Limits on e±μ∓ production in pp collisions at the CERN ISR

Abstract A search for the reaction p+p → e ± μ ± +X at the CERN ISR gave no evidence for this process. Upper limits for e ± μ ∓ /e +- are presented and are related to the branching fraction for leptonic decay of D(1.87).

Upper limit for DD production in pp interactions at C.M. energy of 55 GeV

Abstract From a search for e ± μ ± production at the CERN ISR an upper limit of 0.92 μ b (95% confidence limit) has been inferred for σ · B e · B μ for the reaction p + p → D + D + X at √s of 55 GeV .

Duality and the role of Daughters in KN→πΛ

In the reaction KN→πΛ at Ecm=1.54−2.15 GeV we observe semi-local averaging to zero of the t-channel helicity amplitudes at t≈tmin, as predicted by quark graph duality. The dominant mechanism for averaging is cancellation between Σγ(32−) and Σα(52+), and between Σβ(52−) and Σδ(72+). Daughter resonances appear to cancel semi-locally among themselves following the same pattern. The overall cancellation pattern is between consecutive towers of resonances.