A strong signal for double parton (DP) scattering is observed in a 16 pb(-1) sample of <(p)over bar p> --> gamma/pi(0) + 3 jets + X data from the CDF experiment at the Fermilab Tevatron. In DP events, two separate hard scatterings take place in a single <(p)over bar p> collision. We isolate a large sample of data (similar to 14 000 events) of which 53% are found to be DP. The process-independent parameter of double parton scattering, sigma(eff), is obtained without reference to theoretical calculations by comparing observed DP events to events with hard scatterings in separate <(p)over bar p> collisions. The result sigma(eff) = (14.5 +/- 1.7(-2.3)(+1.7)) mb represents a significant improvement over previous measurements, and is used to constrain simple models of parton spatial density. The Feynman x dependence of sigma(eff) is investigated and none is apparent. Further, no evidence is found for kinematic correlations between the two scatterings in DP events. RI Lancaster, Mark/C-1693-2008; Vucinic, Dejan/C-2406-2008; Chiarelli, Giorgio/E-8953-2012; Azzi, Patrizia/H-5404-2012
Digital Object Identifier (DOI): | http://dx.doi.org/10.1103/PhysRevD.56.3811 |
Codice identificativo ISI: | WOS:A1997YA57300004 |
Codice identificativo Scopus: | 2-s2.0-0642364033 |
Handle: | http://hdl.handle.net/11695/6654 |
Abstract: | A strong signal for double parton (DP) scattering is observed in a 16 pb(-1) sample of <(p)over bar p> --> gamma/pi(0) + 3 jets + X data from the CDF experiment at the Fermilab Tevatron. In DP events, two separate hard scatterings take place in a single <(p)over bar p> collision. We isolate a large sample of data (similar to 14 000 events) of which 53% are found to be DP. The process-independent parameter of double parton scattering, sigma(eff), is obtained without reference to theoretical calculations by comparing observed DP events to events with hard scatterings in separate <(p)over bar p> collisions. The result sigma(eff) = (14.5 +/- 1.7(-2.3)(+1.7)) mb represents a significant improvement over previous measurements, and is used to constrain simple models of parton spatial density. The Feynman x dependence of sigma(eff) is investigated and none is apparent. Further, no evidence is found for kinematic correlations between the two scatterings in DP events. RI Lancaster, Mark/C-1693-2008; Vucinic, Dejan/C-2406-2008; Chiarelli, Giorgio/E-8953-2012; Azzi, Patrizia/H-5404-2012 |
Titolo: | Double parton scattering in (p)over-bar-p collisions at root s=1.8 TeV |
Autori: | |
Appare nelle tipologie: | 1.1 Articolo in rivista |