skip to main content

DOE PAGESDOE PAGES

5 results for: All records
Author ORCID ID is 0000000229371361
Full Text and Citations
Filters
  1. Here, the leading-twist parton distribution amplitudes (PDAs) of ground-state 1S0 and 3S1 cc¯- and bb¯quarkonia are calculated using a symmetry-preserving continuum treatment of the meson bound-state problem which unifies the properties of these heavy-quark systems with those of light-quark bound-states, including QCD's Goldstone modes. Analysing the evolution of 1S0 and 3S1 PDAs with current-quark mass, m^q, increasing away from the chiral limit, it is found that in all cases there is a value of m^q for which the PDA matches the asymptotic form appropriate to QCD's conformal limit and hence is insensitive to changes in renormalisation scale, ζ. This massmore » lies just above that associated with the s-quark. At current-quark masses associated with heavy-quarkonia, on the other hand, the PDAs are piecewise convex–concave–convex.« less
  2. Within contemporary hadron physics there are two common methods for determining the momentum- dependence of the interaction between quarks: the top-down approach, which works toward an ab initiocomputation of the interaction via direct analysis of the gauge-sector gap equations; and the bottom-up scheme, which aims to infer the interaction by fitting data within a well-defined truncation of those equations in the matter sector that are relevant to bound-state properties. We unite these two approaches by demonstrating that the renormalisation-group-invariant running-interaction predicted by contemporary analyses of QCD’s gauge sector coincides with that required in order to describe ground-state hadron observables usingmore » a nonperturbative truncation of QCD’s Dyson–Schwinger equations in the matter sector. This bridges a gap that had lain between nonperturbative continuum-QCD and the ab initio prediction of bound-state properties.« less
    Cited by 48Full Text Available
  3. In order to learn effectively from measurements of generalised parton distributions (GPDs), it is desirable to compute them using a framework that can potentially connect empirical information with basic features of the Standard Model. We sketch an approach to such computations, based upon a rainbow-ladder (RL) truncation of QCD’s Dyson–Schwinger equations and exemplified via the pion’s valence dressed-quark GPD, Hvπ(x, ξ, t). Our analysis focuses primarily on ξ=0, although we also capitalise on the symmetry-preserving nature of the RL truncation by connecting Hvπ(x, ξ=±1, t)with the pion’s valence-quark parton distribution amplitude. We explain that the impulse-approximation used hitherto to definemore » the pion’s valence dressed-quark GPD is generally invalid owing to omission of contributions from the gluons which bind dressed-quarks into the pion. A simple correction enables us to identify a practicable improvement to the approximation for Hvπ(x, 0, t), expressed as the Radon transform of a single amplitude. Therewith we obtain results for Hvπ(x, 0, t) and the associated impact-parameter dependent distribution, qvπ(x, |b⊥|), which provide a qualitatively sound picture of the pion’s dressed-quark structure at a hadronic scale. We evolve the distributions to a scale ζ = 2 GeV, so as to facilitate comparisons in future with results from experiment or other nonperturbative methods.« less
    Cited by 12Full Text Available
  4. The impulse-approximation expression used hitherto to define the pion's valence-quark distribution function is flawed because it omits contributions from the gluons which bind quarks into the pion. A corrected leading-order expression produces the model-independent result that quarks dressed via the rainbow–ladder truncation, or any practical analogue, carry all the pion's light-front momentum at a characteristic hadronic scale. Corrections to the leading contribution may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we use an algebraic model to express the principal impact of both classes of corrections. This enables amore » realistic comparison with experiment that allows us to highlight the basic features of the pion's measurable valence-quark distribution, qπ(x); namely, at a characteristic hadronic scale, qπ(x)~(1-x)2 for x≳0.85; and the valence-quarks carry approximately two-thirds of the pion's light-front momentum.« less
    Cited by 20Full Text Available
  5. Cited by 21Full Text Available

"Cited by" information provided by Web of Science.

DOE PAGES offers free public access to the best available full-text version of DOE-affiliated accepted manuscripts or articles after an administrative interval of 12 months. The portal and search engine employ a hybrid model of both centralized and distributed content, with PAGES maintaining a permanent archive of all full text and metadata.