Measurements of charmed-meson production in interactions between 350 GeV/c π− particles and nuclei

Abstract

Charmed-meson production by 350 GeV/c particles incident on copper and tungsten targets has been studied in the WA92 experiment, performed at the CERN 0 spectrometer. Results obtained are reported and discussed. Reconstruction of decays from the set D 0 ! K + , D 0 ! K + + , D + ! K + + , D s + ! + and charge conjugates has yielded a sample of 7280 108 charmed mesons, produced with X F > 0, hX F i = 0:18 and hp T 2 i = 1:86 (GeV=c) 2 . Assuming a relationship = 0 A between the cross-section, , per nucleus of mass A and the nucleonic cross-section, 0 , the value found for the detected charmed particles is 0:95 0:06 0:03. Taking = 1 , the measured cross-sections per nucleon for X F > 0 production are 7:780:140:52 barn for D 0 / D 0 , 3 : 280:080:29 barn for D + /D and 1:29 0:16 0:33 barn for D s + /D s . Dierential cross-sections with respect to X F and p T 2 have been determined for the various types of charmed meson, and particle-antiparticle asymmetries have been analysed.

Determination of the total

“…The same dependence was used in the analyses of the proton beam experiments listed in table 4. The most precise measurements of the exponent α in charm production come from the pion beam experiments WA82 [14], E769 [15] and BEAT-RICE(WA92) [16]. The averages from the three experiments are α = 0.95 ± 0.04 for both D 0 /D 0 and D ± production, with no significant dependence of α on the longitudinal or transverse momenta.…”

Final tau-neutrino results from the DONuT experiment

“…µb/nucl µb/nucl µb/nucl [13] p/800 37 ± 9 ± 12 43 ± 3 ± 14 NA [16] p/800 26 ± 4 ± 7 22 ± 8 ± 6 NA [22] p/920 29.9 ± 4.5 ± 5.7 56.3 ± 8.5 ± 9.5 NA [17] p/250 3.3 ± 0.4 ± 0.4 6.0 ± 1.4 ± 0.5 1.5 ± 1.5 [15] π/230 3.2 ± 0.2 ± 0.7 6.6 ± 0.3 ± 1.0 2.7 ± 0.2 [17] π/250 3.6 ± 0.2 ± 0.3 8.7 ± 0.7 ± 0.6 2.0 ± 0.5 [17] K/250 3.0 ± 0.4 7.2 ± 1.1 3.0 ± 0.9 [17] p/250 3.2 ± 0.5 5.4 ± 1.4 1.5 ± 1.5 [18] π/350 3.2 ± 0.1 ± 0.3 7.8 ± 0.14 ± 0.5 1.3 ± 0.4 Avg.…”

Measurement of the cross section of charmed hadrons and the nuclear dependence alpha

“…El experimento E789 [19] utilizó un haz de protones a 800 GeV/c sobre blancos de Berilio y Oro, observaron 2400 mesones D 0 , su rango en x F es de 0.0-0.08 y para p t < 1.1 GeV/c. WA92 [10] …”

“…Muchos experimentos han medido la sección eficaz total de charm principalmente para los haces de protones y π, los experimentos con el haz de protones son NA32, NA27, E743, E653, E769, y HERA-B [1,2,3,4,5,6], respectivamente, los experimentos XXXVIII Introducción y Motivación para el haz de π son NA27 [7], NA32 [1,8], E653 [9], E769 [5], WA92 [10], y E791 [11], muchos de estos resultados son sólo para los mesones D (cargados y neutrales). Pero para obtener la sección eficaz total de charm además de sumar los valores obtenidos de los mesones D (neutrales y cargados), se tienen que tomar en cuenta la producción de otros hadrones con charm (D s , Λ c y otros bariones charm).…”

“…Estos experimentos son BIS-2 [15], WA82 [16], E769 [17,18], E789 [19], WA92 [10], E706 [20], y HERA-B [6], la mayoría de estos experimentos solamente publicaron un valor promedio para el parámetro α, aunque es importante señalar que 3 de estos experimentos muestran el parámetro α como función de x F y p t , estos son [16,17,10]. La mayoría de los valores son consistentes con α=1 [21].…”