Observation of polarization in bottomonium production at root s=38.8 GeV

Authors
Brown, CN Awes, TC Beddo, ME Brooks, ML Bush, JD Carey, TA Chang, TH Cooper, WE Gagliardi, CA Garvey, GT Geesaman, DF Hawker, EA He, XC Isenhower, LD Kaplan, DM Kaufman, SB Kirk, PN Koetke, DD Kyle, G Lee, DM Lee, WM Leitch, MJ Makins, N McGaughey, PL Moss, JM Mueller, BA Nord, PM Papavassiliou, V Park, BK Peng, JC Petitt, G Reimer, PE Sadler, ME Sondheim, WE Stankus, PW Thompson, TN Towell, RS Tribble, RE Vasiliev, MA Webb, JC Willis, JL Wise, DK Young, GR
Citation
Cn. Brown et al., Observation of polarization in bottomonium production at root s=38.8 GeV, PHYS REV L, 86(12), 2001, pp. 2529-2532
Citations number
29
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW LETTERS
ISSN journal
00319007 → ACNP
Volume
86
Issue
12
Year of publication
2001
Pages
2529 - 2532
Database
ISI
SICI code
0031-9007(20010319)86:12<2529:OOPIBP>2.0.ZU;2-R
Abstract
We present a measurement of the polarization observed for bottomonium state s produced in p-Cu collisions at roots = 38.8 GeV. The angular distribution of the decay dimuons of the Y (1S) state shows no polarization at small va lues of the fractional longitudinal momentum chi (F) add transverse momentu m p(T) but significant positive transverse production polarization for eith er p(T) > 1.8 GeV/c or for chi (F) > 0.35. The Y (2S + 3S) (unresolved) sta tes show a large transverse production polarization at all values of chi (F ) and pr measured. These observations challenge NRQCD calculations of the p olarization expected in the hadronic production of bottomonium states.