Upsilonium Polarization as a Touchstone in Understanding the Parton Dynamics in Qcd
نویسنده
چکیده
In the framework of the kt-factorization approach, the production of Υ mesons at the Fermilab Tevatron is considered, and the comparisions of calculated pT distributions and spin alignment parameter α with the D0 experimental data are shown. We argue that measuring the double cross section and the polarization of upsilonium states can serve as a crucial test discriminating two competing theoretical approaches to parton dynamics in QCD.
منابع مشابه
ترکش گلوئون به چارمونیوم برداری J/psi با در نظر گرفتن اثر تابع موج مزون
Studying the production or decay processes of heavy quarkonia (the bound state of heavy quark-antiquark) is a powerful tool to test our understanding of strong interaction dynamics and QCD theory. Fragmentation is the dominant production mechanism for heavy quarkonia with large transverse momentum. The fragmentation refers to the production process of a parton with high transverse momentum whic...
متن کاملبررسی مدلهای گوناگون QCD و مقایسه آنها با نتایج حاصل از نابودی e+e- در انرژی مرکز جرم60GeV
We present the QCD models based on the hadronization of final states of e+e- annihilations, in 60 GeV centre of mass energy in the AMY detector at the KEK collider TRISTAN. To achieve this, we first find the jet axis by using the momentum tensor and diagonilizing it for each event. The models under consideration are the Webber, the Matrix Elements and the Parton Shower. In most cases our resu...
متن کاملFactorization for hard exclusive electroproduction of mesons in QCD
We formulate and prove a QCD factorization theorem for hard exclusive electroproduction of mesons in QCD. The proof is valid for the leading power in Q and all logarithms. This generalizes previous work on vector meson production in the diffractive region of small x. The amplitude is expressed in terms of off-diagonal generalizations of the usual parton densities. The full theorem applies to al...
متن کاملHelicity dependent parton distributions
The helicity dependent parton distributions describe the number density of partons with given longitudinal momentum x and given polarization in a hadron polarized longitudinally with respect to its motion. After the discovery , more than 70 years ago , that the proton is not elementary , the observation of Bjorken scaling in the late 1960s lead to the idea of hadrons containing almost pointlike...
متن کاملNext-to-leading order QCD corrections to ATT for prompt photon production
We present a next-to-leading order QCD calculation of the cross section for isolated large-pT prompt photon production in collisions of transversely polarized protons. We devise a simple method of dealing with the phase space integrals in dimensional regularization in the presence of the cos(2Φ) azimuthal-angular dependence occurring for transverse polarization. Our results allow to calculate t...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2008