b-quark and quarkonium production and polarisation
نویسندگان
چکیده
منابع مشابه
Recent Developments in Heavy Quark and Quarkonium Production
Recent measurements of J/ψ production in ee colliders pose a challenge to the NRQCD factorization theorem for quarkonium production. Discrepancies between leading order calculations of color-octet contributions and the momentum distribution of J/ψ observed by Belle and BaBar are resolved by resumming large perturbative and nonperturbative corrections that are enhanced near the kinematic endpoin...
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The strange quark helicity distribution ∆s(x) is derived at LO from the semi-inclusive and inclusive spin asymmetries measured by the COMPASS experiment at CERN. The significance of the results is found to depend critically on the ratio of the s and u quark fragmentation functions into kaons ∫ DK+ s (z)dz/ ∫ DK+ u (z)dz.
متن کاملLight Quark Masses and Quarkonium Decays
After discussing the intrinsic ambiguity in determining the light quark mass ratio mu/md, we reexamine the recent proposal that this ambiguity can be resolved by applying the QCD multipole expansion for the heavy quarkonium decays. It is observed that, due to instanton effects, some matrix elements which have been ignored in previous works can give a significant contribution to the decay amplit...
متن کاملHeavy Quark Interactions and Quarkonium Binding
We consider heavy quark interactions in quenched and unquenched lattice QCD. In a region just above the deconfinement point, non-Abelian gluon polarization leads to a strong increase in the binding. Comparing quark-antiquark and quark-quark interaction, the dependence of the binding on the separation distance r is found to be the same for the colorless singlet QQ̄ and the colored anti-triplet QQ...
متن کاملQuarkonium Decays and Light Quark Masses
The SU(3)-violating decays Φ →ΦX , where X = π or η and Φ = J/ψ or Υ have been recently proposed as a means of probing the light quark masses beyond leading order in chiral perturbation theory. We argue that this analysis is incorrect, even in the heavy quark limit. We show that these decays are governed by an infinite number of matrix elements which are not suppressed by any small parameter, a...
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ژورنال
عنوان ژورنال: EPJ Web of Conferences
سال: 2013
ISSN: 2100-014X
DOI: 10.1051/epjconf/20134913008