Main Page

From HFA-PEDIA

Revision as of 11:06, 2 January 2018 by Polo89view (Talk | contribs)
Jump to: navigation, search

Zation conjecture has by now received most acceptance, although not but becoming totally established. 4.5.1 Summary of recent experimental progress The past couple of years have seen extraordinary progress in measurements of quarkonium production observables, which was mostly, but not solely, due to the operation of your various LHC experiments. Here we'll give an overview from the most exceptional outcomes of your previous years. The production prices of a heavy quarkonium H are split into direct, prompt, and nonprompt contributions. Direct production refers to the production of H straight at the interaction point from the initial particles, even though prompt production also involves production by way of radiative http://lisajobarr.com/members/coilinput8/activity/755824/ decays of greater quarkonium states, called feed-down contributions. Nonprompt production refers to all other production mechanisms, mostly the production of charmonia from decaying B mesons, which could be identified by a second decay vertex displaced in the interaction point. a. J/ production in pp collisions The 2004 CDF transverse momentum pT distribution measurement of the J/ production cross section [1141] is still among probably the most precise heavy quarkonium production measurements. But since theory errors in all models for heavy quarkonium production are still substantially larger than today's experimental errors, it really is in general not greater precision that is needed from the theory side, but rather new and much more title= fpsyg.2017.00209 diverse production observables. And this is exactly where the LHC experiments have provided very important input. As for the J/ hadroproduction cross section, they've extended the CDF measurement [1141] into new kinematic regions: Of course, the measurements have already been performed at much greater center-of-mass energies than before, namely at s = two.76, 7, and 8 TeV. But a lot more vital for testing quarkonium production models will be the fact that there are actually measurements which exceed the previously measured pT variety each at higher pT , as by ATLAS [1142] and CMS [1143], and at low pT , as inside the earlier CMS measurement [1144], but in addition within the recent measurement by the PHENIX collaboration at RHIC [1145]. We note that this list just isn't complete, and that there have been numerous far more J/ hadroproduction measurements not too long ago than these cited right here. b. (2S) and c production in pp collisions J/ is the quarkonium that is easiest to be measured as a consequence of thelarge branching ratio of its leptonic decay modes, but in current years, higher precision measurements have already been also performed for the (2S), namely by the CDF [1146], the CMS [1143], as well as the LHCb [1147] collaborations. Also the c production cross sections had been measured by means of their decays into J/ by LHCb [1148], the first time because the CDF measurement [1149] in 2001. The c2 to c1 production ratio was measured at LHCb [1150], CMS [1151] and previously by title= 17470919.2015.1029593 CDF [1152]. These measurements are of good significance for the theory side because they let fits of NRQCD LDMEs for these charmonia and figure out direct J/ production data, which can in turn be in comparison with direct production theory predictions. c. production in pp collisions (1S), (2S), and (3S) production cross sections had been measured in the LHC by ATLAS [1153] and LHCb [1154,1155].

Personal tools