Transition between nuclear and quark–gluon descriptions of hadrons and light nuclei

Gilman, R.

doi:10.1088/0034-4885/75/8/086301

Cited by 42 publications

(49 citation statements)

References 257 publications

(273 reference statements)

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“…Furthermore, the associated discussion supports a view that ϕ asy π (x) is a poor approximation to ϕ π (x; τ ) at all momentum-transfer scales that are either now accessible to experiments involving pion elastic or transition processes, or will become so in the foreseeable future [9,13,55,56]. Available information indicates that the pion's PDA is significantly broader at these scales; and hence that predictions of leading-order, leading-twist formulae involving ϕ asy π (x) are a misleading guide to interpreting and understanding contemporary experiments.…”

Section: Gevmentioning

confidence: 74%

Pion Distribution Amplitude from Lattice QCD

Cloët¹,

Chang²,

Roberts³

et al. 2013

Phys. Rev. Lett.

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A method is explained through which a pointwise accurate approximation to the pion's valencequark distribution amplitude (PDA) may be obtained from a limited number of moments. In connection with the single nontrivial moment accessible in contemporary simulations of latticeregularised quantum chromodynamics (QCD), the method yields a PDA that is a broad concave function whose pointwise form agrees with that predicted by Dyson-Schwinger equation analyses of the pion. Under leading-order evolution, the PDA remains broad to energy scales in excess of 100 GeV, a feature which signals persistence of the influence of dynamical chiral symmetry breaking. Consequently, the asymptotic distribution, ϕ asy π (x), is a poor approximation to the pion's PDA at all such scales that are either currently accessible or foreseeable in experiments on pion elastic and transition form factors. Thus, related expectations based on ϕ asy π (x) should be revised.PACS numbers: 14.40. Be, 12.38.Aw, 12.38.Gc, 12.38.Lg The light-front wave-function of an interacting quantum system, ϕ(x), provides a connection between dynamical properties of the underlying relativistic quantum field theory and notions familiar from nonrelativistic quantum mechanics. In particular, although particle number conservation is generally lost in relativistic quantum field theory, ϕ(x) has a probability interpretation. It can therefore translate features that arise purely through the infinitely-many-body nature of relativistic quantum field theory into images whose interpretation seems more straightforward [1][2][3].With ϕ(x) in hand, the impact of phenomena that are essentially quantum field theoretical in origin may be expressed via wave-function overlaps. Such overlaps are familiar in all disciplines and associated with a longestablished interpretation. For example, the (leadingtwist) wave-function of a meson is an amplitude that describes the momentum distribution of a quark and antiquark in the bound-state's simplest (valence) Fock state. The amplitude, ϕ(x), is a process-independent expression of intrinsic properties of the composite system. Seemingly, the simplest composite systems in nuclear and particle physics are the pions. This isospin triplet of (unusually) low-mass states are constructed from valence u-and d-quarks. As a process-independent expression of pion properties, ϕ π (x) is a crucial element in computing the leading-twist and leading-order in α-strong results for pion elastic and transition form factors [4][5][6]. For many years, predictions obtained with such formulae have served as motivation for crucial experiments designed to test QCD; e.g., Refs. [7][8][9][10][11][12][13].Regarding the pion, however, appearances have long been deceiving. The unusually low mass of these states signals the intimate connection between dynamical chiral symmetry breaking (DCSB) and the existence and properties of pions. This connection is fascinating because DCSB is a striking emergent feature of QCD, which plays a critical role in forming the bulk of the visi...

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Section: Gevmentioning

confidence: 74%

Pion Distribution Amplitude from Lattice QCD

Cloët¹,

Chang²,

Roberts³

et al. 2013

Phys. Rev. Lett.

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“…Results are compared to data taken from Refs. [1,13] and references within. The shaded bands correspond to values for the scale parameter κ in the range of 150−250 MeV.…”

Section: Formalism and Numerical Resultsmentioning

confidence: 99%

Deuteron electromagnetic structure functions and polarization properties in soft-wall AdS/QCD

2016

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We apply a soft-wall AdS/QCD approach to the description of deuteron structure functions and tensor polarized properties. Present work is a completion of our previous study on electromagnetic form factors. By the appropriate choice of two couplings in the effective action we are able to reproduce both the form factors and structure functions in full consistency with model-independent constraints set by perturbative QCD. Our framework is based on a five-dimensional action in AdS space formulated in terms of vector fields dual to the deuteron and the electromagnetic fields. The AdS fields depend on four Minkowski and one holographic coordinate z. The scale dependence of the form factors and structure functions is consistent with quark counting rules implying the 1/Q 10 behavior of the charge form factor GC(Q 2 ), structure functions A(Q 2 ) and B(Q 2 ), and the 1/Q 12 behavior of the magnetic GM (Q 2 ) and quadrupole GQ(Q 2 ) form factors.

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“…The predictions are in remarkable agreement with measurements. [30,31] 3.1 Holographic embedding and the spin-spin interaction [5] The pion and nucleon trajectories can be consistently described by the superconformal algebraic structure mapped to the light front [4]. A fundamental prediction is a massless pion in the limit of zero quark masses.…”

Section: The Eigenfunctions Of the Hamiltonianmentioning

confidence: 99%

Meson/baryon/tetraquark supersymmetry from superconformal algebra and light-front holography

Brodsky

Téramond

Dosch

et al. 2016

Int. J. Mod. Phys. A

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Superconformal algebra leads to remarkable connections between the masses of mesons and baryons of the same parity -supersymmetric relations between the bosonic and fermionic bound states of QCD. Supercharges connect the mesonic eigenstates to their baryonic superpartners, where the mesons have internal angular momentum one unit higher than the baryons: L M = L B + 1. The dynamics of the superpartner hadrons also match; for example, the power-law fall-off of the form factors are the same for the mesonic and baryonic superpartners, in agreement with twist counting rules. An effective supersymmetric light-front Hamiltonian for hadrons composed of light quarks can be constructed by embedding superconformal quantum mechanics into AdS space. This procedure also generates a spin-spin interaction between the hadronic constituents. A specific breaking of conformal symmetry inside the graded algebra determines a unique quark-confining light-front potential for light hadrons in agreement with the softwall AdS/QCD approach and light-front holography. Only one mass parameter √ λ appears; it sets the confinement mass scale, a universal value for the slope of all Regge trajectories, the nonzero mass of the proton and other hadrons in the chiral limit, as well as the length scale which underlies their structure. The mass for the pion eigenstate vanishes in the chiral limit. When one includes the constituent quark masses using the Feynman-Hellman theorem, the predictions are consistent with the empirical features of the light-quark hadronic spectra. Our analysis can be consistently applied to the excitation spectra of the π, ρ, K, K * and φ meson families as well as to the N, ∆, Λ, Σ, Σ * , Ξ and Ξ * baryons. We also predict the existence of tetraquarks which are degenerate in mass with baryons with the same angular momentum. The mass-squared of the light hadrons can be expressed in a universal and frame-independent decomposition of contributions from the constituent kinetic energy, the confinement potential, and spin-spin contributions. We also predict features of hadron dynamics, including hadronic light-front wavefunctions, distribution amplitudes, form factors, valence structure functions and vector meson electroproduction phenomenology. The mass scale √ λ can be connected to the parameter Λ M S in the QCD running coupling by matching the nonperturbative dynamics, as described by the light-front holographic approach. to the perturbative QCD regime. The result is an effective coupling defined at all momenta. The matching of the high and low momentum-transfer regimes determines a scale Q 0 proportional to √ λ which sets the interface between perturbative and nonperturbative hadron dynamics. The use of Q 0 to resolve the factorization scale uncertainty for structure functions and distribution amplitudes, in combi-2 nation with the scheme-independent Principle of Maximal Conformality (PMC) procedure for setting renormalization scales, can greatly improve the precision of perturbative QCD predictions.

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Transition between nuclear and quark–gluon descriptions of hadrons and light nuclei

Cited by 42 publications

References 257 publications

Pion Distribution Amplitude from Lattice QCD

Pion Distribution Amplitude from Lattice QCD

Deuteron electromagnetic structure functions and polarization properties in soft-wall AdS/QCD

Meson/baryon/tetraquark supersymmetry from superconformal algebra and light-front holography

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