Polarization in Quarkonium Production

Conference · Wed Aug 01 04:00:00 EDT 2012

OSTI ID:1419172

Russ, James S.

Production mechanisms for quarkonium states in hadronic collisions remain difficult to understand. The decay angular distributions of J/$$\psi$$ or $$\Upsilon(nS)$$ states into $$\mu^+ \mu^-$$ final states are sensitive to the matrix elements in the production process and provide a unique tool to evaluate different models. This talk will focus on new results for the spin alignment of $$\Upsilon(nS)$$ states produced in $$p\bar{p}$$ collisions at $$\sqrt{s}$$ = 1.96 TeV using the CDF II detector at the Fermilab Tevatron. The data sample corresponds to an integrated luminosity of 6.7 fb$$^{-1}$$. The angular distributions are analyzed as functions of the transverse momentum of the dimuon final state in both the Collins-Soper and the s-channel helicity frames using a unique data-driven background determination method. Consistency of the analysis is checked by comparing frame-invariant quantities derived from parametrizations of the angular distributions measured in each choice of reference frame. This analysis is the first to quantify the complete three-dimensional angular distribution of $$\Upsilon(1S), \Upsilon(2S)$$ and $$\Upsilon(3S)$$ decays. The decays are nearly isotropic in all frames, even when produced with large transverse momentum.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• Contributing Organization: CDF
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 1419172
• Report Number(s): arXiv:1208.4292; FERMILAB-CONF-12-478-PPD; 1128461
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS