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Nuclear Theory·nucl-th

Wednesday·May 24, 2017

9 papers—7 primary·2 cross-listed

All9Primary7Cross-lists2
  1. 08

    [Submitted on 23 May 2017] (cross-list from hep-ph)

    New explicit expressions for Dirac bilinears

    Cédric Lorcé (Ecole polytechnique, CPHT)🇫🇷

    We derive new explicit expressions for the Dirac bilinears based on a generic representation of the massive Dirac spinors with canonical polarization. These bilinears depend on a direction in Minkowski space which specifies the form of dynamics. We argue that such a dependence is unavoidable in a relativistic theory with spin, since it originates from Wigner rotation effects. Contrary to most of the expressions found in the literature, our ones are valid for all momenta and canonical polarizations of the spinors. As a by-product, we also obtain a generic explicit expression for the covariant spin vector.

    Comments:
    9 pages, version accepted in PRD
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1705.08370 [pdf]
    PRD(2018)·43 citations
  2. 09

    [Submitted on 23 May 2017] (cross-list from hep-ph)

    The transverse momentum distribution of hadrons within jets

    Zhong-Bo Kang🇺🇸 · Xiaohui Liu🇨🇳 · Felix Ringer🇺🇸 · Hongxi Xing🇺🇸

    We study the transverse momentum distribution of hadrons within jets, where the transverse momentum is defined with respect to the standard jet axis. We consider the case where the jet substructure measurement is performed for an inclusive jet sample . We demonstrate that this observable provides new opportunities to study transverse momentum dependent fragmentation functions (TMDFFs) which are currently poorly constrained from data, especially for gluons. The factorization of the cross section is obtained within Soft Collinear Effective Theory (SCET), and we show that the relevant TMDFFs are the same as for the more traditional processes semi-inclusive deep inelastic scattering (SIDIS) and electron-positron annihilation. Different than in SIDIS, the observable for the in-jet fragmentation does not depend on TMD parton distribution functions which allows for a cleaner and more direct probe of TMDFFs. We present numerical results and compare to available data from the LHC.

    Comments:
    28 pages, 3 figures, published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1705.08443 [pdf]
    JHEP(2017)·113 citations

Affiliations

first authorsco-authorsvia INSPIRE