Relativistic two-photon and two-gluon decay rates of heavy quarkonia

Gupta, Suraj N.; Johnson, James M.; Repko, Wayne W.

doi:10.1103/physrevd.54.2075

Cited by 74 publications

(65 citation statements)

References 13 publications

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“…As in our approach, they include the effects of the bound state wave function on the initial decaying particle. Gupta, Johnson, and Repko [44] follow a similar approach. The two numbers displayed in their column correspond to two distinct approaches used in incorporating off shell effects.…”

Section: A Charmoniummentioning

confidence: 99%

“…To be more explicit, the portion of the Feynman propagator (p − − k 1 ) 2 + m 2 − i0 in the approaches of [16] and the first of [44] is treated as 2p · k+w p 2 + m 2 , in the second of [44] as 2p · k+w 2 /2 and in the constraint approach as (p − k) 2 + m 2 . The treatment of the spin-dependent aspects of the wave function in [16], [44], and [45] is similar to that appearing in our earlier paper on positronium decay in [15]. We point out, however, that in our paper here, the spin dependent aspects of the wave function do not arise from the free spinor factors in the Feynman decay amplitude, but rather from the multicomponent structure of the interacting TBDE.…”

Section: A Charmoniummentioning

confidence: 99%

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Tests of two-body Dirac equation wave functions in the decays of quarkonium and positronium into two photons

2006

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Two-Body Dirac equations of constraint dynamics provide a covariant framework to investigate the problem of highly relativistic quarks in meson bound states. This formalism eliminates automatically the problems of relative time and energy, leading to a covariant three dimensional formalism with the same number of degrees of freedom as appears in the corresponding nonrelativistic problem. It provides bound state wave equations with the simplicity of the nonrelativistic Schrödinger equation. Here we begin important tests of the relativistic sixteen component wave function solutions obtained in a recent work on meson spectroscopy, extending a method developed previously for positronium decay into two photons. Preliminary to this we examine the positronium decay in the 3 P0,2 states as well as the 1 S0. The two-gamma quarkonium decays that we investigate are for the η c , η ′ c , χ c0 , χ c2 , π 0 , π2, a2,and f ′ 2 mesons. Our results for the four charmonium states compare well with those from other quark models and show the particular importance of including all components of the wave function as well as strong and CM energy dependent potential effects on the norm and amplitude. The results for the π 0 , although off the experimental rate by 15%, is much closer than the usual expectations from a potential model. We conclude that the Two-Body Dirac equations lead to wave functions which provide good descriptions of the two-gamma decay amplitude and can be used with some confidence for other purposes.

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Section: A Charmoniummentioning

confidence: 99%

Section: A Charmoniummentioning

confidence: 99%

Tests of two-body Dirac equation wave functions in the decays of quarkonium and positronium into two photons

2006

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“…Among them, the electromagnetic decay χ c0,2 → γγ provide a particularly interesting, and, rich testing ground of QCD [3,4]. In the past decades, these decay channels have been extensively studied from various theoretical angles, such as nonrelativistic potential model [5,6], relativistic quark model [7][8][9], Bethe-Salpeter approach [10], nonrelativistic QCD (NRQCD) factorization [11,12], as well as lattice QCD [13]. On the experimental side, they were previously measured by .…”

mentioning

confidence: 99%

“…This is impressively consistent with the measurement (2a). Nevertheless, these processes are sensitive to the next-to-leading-order (NLO) radiative correction [17,18], with the predicted R scattered in the range from 0.09 to 0.36 [6,7].…”

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confidence: 99%

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Next-to-next-to-leading-order QCD corrections to χc0,2→γγ

et al. 2016

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We calculate the next-to-next-to-leading-order (NNLO) perturbative corrections to P -wave quarkonia annihilation decay to two photons, in the framework of nonrelativistic QCD (NRQCD) factorization. The order-α 2 s short-distance coefficients associated with each helicity amplitude are presented in a semi-analytic form, including the "light-by-light" contributions. With substantial NNLO corrections, we find disquieting discrepancy when confronting our state-of-the-art predictions with the latest BESIII measurements, especially fail to account for the measured χc2 → γγ width. Incorporating the effects of spin-dependent forces would even exacerbate the situation, since it lifts the degeneracy between the nonperturbative NRQCD matrix elements of χc0 and χc2 toward the wrong direction. We also present the order-α 2 s predictions to χ b0,2 → γγ, which await the future experimental test. Charmonium decay has historically played an important role in establishing the asymptotic freedom of QCD, and served as a clean platform to probe the interplay between pertubative and nonperturbative dynamics [1,2]. Among them, the electromagnetic decay χ c0,2 → γγ provide a particularly interesting, and, rich testing ground of QCD [3,4]. In the past decades, these decay channels have been extensively studied from various theoretical angles, such as nonrelativistic potential model [5,6], relativistic quark model [7][8][9], Bethe-Salpeter approach [10], nonrelativistic QCD (NRQCD) factorization [11,12], as well as lattice QCD [13]. On the experimental side, they were previously measured by . BESIII experiment [15] has recently reported their high precision results, Γ γγ (χ c0 ) = (2.33 ± 0.20 ± 0.13 ± 0.17) keV, (1a) Γ γγ (χ c2 ) = (0.63 ± 0.04 ± 0.04 ± 0.04) keV. (1b)

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Measurement of two-photon decay width of χc2(1P) in γγ → χc2(1P) → J/ψγ at Belle

Seino¹,

Hayasaka²,

Uehara³

et al. 2023

J. High Energ. Phys.

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We report the measurement of the two-photon decay width of χc2(1P) in two-photon processes at the Belle experiment. We analyze the process γγ → χc2(1P) → J/ψγ, J/ψ → ℓ+ℓ− (ℓ = e or μ) using a data sample of 971 fb−1 collected with the Belle detector at the KEKB e+e− collider. In this analysis, the product of the two-photon decay width of χc2(1P) and the branching fraction is determined to be $$ {\Gamma}_{\gamma \gamma}\left({\chi}_{c2}(1P)\right)\mathcal{B}\left({\chi}_{c2}(1P)\to J/\psi \gamma \right)\mathcal{B}\left(J/\psi \to {\ell}^{+}{\ell}^{-}\right)=14.8\pm 0.3\left(\textrm{stat}.\right)\pm 0.7\left(\textrm{syst}.\right) $$ Γ γγ χ c 2 1 P B χ c 2 1 P → J / ψγ B J / ψ → ℓ + ℓ − = 14.8 ± 0.3 stat . ± 0.7 syst . eV, which corresponds to Γγγ(χc2(1P)) = 653 ± 13(stat.) ± 31(syst.) ± 17(B.R.) eV, where the third uncertainty is from $$ \mathcal{B} $$ B (χc2(1P) → J/ψγ) and $$ \mathcal{B} $$ B (J/ψ → ℓ+ℓ−).

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Relativistic two-photon and two-gluon decay rates of heavy quarkonia

Cited by 74 publications

References 13 publications

Tests of two-body Dirac equation wave functions in the decays of quarkonium and positronium into two photons

Tests of two-body Dirac equation wave functions in the decays of quarkonium and positronium into two photons

Next-to-next-to-leading-order QCD corrections to χc0,2→γγ

Measurement of two-photon decay width of χc2(1P) in γγ → χc2(1P) → J/ψγ at Belle

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