Production of Charmonium at Threshold in Hall A and C at Jefferson Lab

Hafidi, K.; Joosten, S.; Meziani, Z. E.; Qiu, Jian‐Wei

doi:10.1007/s00601-017-1305-3

Cited by 13 publications

(10 citation statements)

References 48 publications

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“…The absence of massless modes in the scalar channel requires that C = Ã. This can also be checked by inserting (7) in (1) and tracing, so that p|T µ µ (0)|p = 2 Cm 2 N in any frame. Similarly, the 00-component of the energy momentum tensor gives p|T 00 (0)|p = 2 Ãp 2 0 → 2 Ãm 2 N , with the rightmost result following in the rest frame only.…”

Section: B D-termmentioning

confidence: 99%

“…While decisive understanding of these two phenomena has been achieved theoretically and numerically using lattice QCD simulations [5,6], empirical measurements to support this understanding is only now emerging at current and dedicated electron machines [7][8][9][10]. Recently, the GlueX collaboration [8] at JLAB has reported threshold data for photoproduction of charmonium J/Ψ that may start to lift the lid on some of these fundamental questions.…”

Section: Introductionmentioning

confidence: 99%

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Nucleon mass radii and distribution: Holographic QCD, Lattice QCD and GlueX data

Mamo,

Zahed

2021

Preprint

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We briefly review and expand our recent analysis for all three invariant A,B,D gravitational form factors of the nucleon in holographic QCD. They compare well to the gluonic gravitational form factors recently measured using lattice QCD simulations. The holographic A-term is fixed by the tensor T = 2 ++ (graviton) Regge trajectory, and the D-term by the difference between the tensor T = 2 ++ (graviton) and scalar S = 0 ++ (dilaton) Regge trajectories. The B-term is null in the absence of a tensor coupling to a Dirac fermion in bulk. A first measurement of the tensor form factor A-term is already accessible using the current GlueX data, and therefore the tensor gluonic mass radius, pressure and shear inside the proton, thanks to holography. The holographic A-term and D-term can be expressed exactly in terms of harmonic numbers. The tensor mass radius from the holographic threshold is found to be r 2 GT ≈ (0.57 − 0.60 fm) 2 , in agreement with r 2 GT ≈ (0.62 fm) 2 as extracted from the overall numerical lattice data, and empirical GlueX data. The scalar mass radius is found to be slightly larger r 2 GS ≈ (0.7 fm) 2 .

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Section: B D-termmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nucleon mass radii and distribution: Holographic QCD, Lattice QCD and GlueX data

Mamo,

Zahed

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Recently, the GlueX collaboration has put forth measurements of threshold charmonium production using virtual photons close to the photon point [15]. Additional measurements at JLab in this channel with higher accuracy using the SoLID detector should improve further the statistics [16]. One purpose of these experiments is the extraction of the gluonic component entering the composition of the nucleon mass.…”

Section: Introductionmentioning

confidence: 99%

Diffractive photoproduction of J/ψ and ϒ using holographic QCD: Gravitational form factors and GPD of gluons in the proton

Mamo

Zahed

2020

Phys. Rev. D

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We present a holographic analysis of diffractive photoproducton of charmonium J/ψ and upsilonium Υ on a proton, considered as a bulk Dirac fermion, for all ranges of √ s, i.e., from near threshold to very high energy. Using the bulk wave functions of the proton and vector mesons, within holographic QCD, and employing Witten diagrams in the bulk, we compute the diffractive photoproduction amplitude of J/ψ and Υ. The holographic amplitude shows elements of the strictures of vector meson dominance (VMD). It is dominated by the exchange of a massive graviton or 2 ++ glueball resonances near threshold, and its higher spin-j counterparts that reggeize at higher energies. Both the differential and total cross sections are controlled by the gravitational form factor A(t), and compare well to the recent results reported by the GlueX collaboration near threshold and the world data at large √ s. The holographic gravitational form factors, including the D-term, which is due to the exchange of massive spin-0 glueballs, are in good agreement with lattice simulations. We use it to extract the holographic pressure and shear forces inside the proton. Finally, using a pertinent integral representation of the holographic gravitational form factor A(t) near threshold, and its Pomeron counterpart way above threshold, we extract the generalized parton distribution (GPD) of gluons inside the proton at different resolutions.

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“…Apart from the light-cone sum rules, an empirical way to measure the gluon contribution to the mass sum rule of the nucleon, is through diffractive photo-or electroproduction of heavy mesons off nucleons near treshold as suggested intially in [27], and pursued experimentally in [28,29]. The threshold cross section is dominated by glueball-like exchanges with tensor and scalar quantum numbers.…”

Section: Form Factors Of the Energy-momentum Tensormentioning

confidence: 99%

Mass structure of hadrons and light-front sum rules in t' Hooft model

Ji,

Liu,

Zahed

2020

Preprint

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We study the mass/energy structure of the bound state of hadrons in two-dimensional quantum chromodynamics in the large number of color limit (t' Hooft model). We analyze separately the contributions from the traceless and trace part of the energy-momentum tensor, and show that the masses are related to the matrix elements of the scalar charge and Coulomb energy. We derive the light-front sum rules for the scalar charge and Coulomb energy, expressed in terms of the light-front wave functions, and find that they are regular at x = 0 without the delta function contribution. We also consider the result for the massless Goldstone boson, as well as the structure of the gravitational form factors of the bound meson states.

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Production of Charmonium at Threshold in Hall A and C at Jefferson Lab

Cited by 13 publications

References 48 publications

Nucleon mass radii and distribution: Holographic QCD, Lattice QCD and GlueX data

Nucleon mass radii and distribution: Holographic QCD, Lattice QCD and GlueX data

Diffractive photoproduction of J/ψ and ϒ using holographic QCD: Gravitational form factors and GPD of gluons in the proton

Mass structure of hadrons and light-front sum rules in t' Hooft model

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