First-principle calculation of ${\eta }_c\to 2\gamma$ decay width from lattice QCD

Abstract

We perform a lattice QCD calculation of the ${\eta }_c\to 2\gamma$ decay width using a model-independent method that requires no momentum extrapolation of the off-shell form factors. This method also provides a straightforward and simple way to examine the finite-volume effects. The calculation is accomplished using $N_f=2$ twisted mass fermion ensembles. The statistically significant excited-state effects are observed and eliminated using a multi-state fit.The impact of fine-tuning the charm quark mass is also examined and confirmed to be well-controlled. Finally, using three lattice spacings for the continuum extrapolation, we obtain the decay width ${\Gamma }_{{\eta }_c\gamma \gamma }=6.67(16{)}_{\mathrm{stat}}(6{)}_{\mathrm{syst}}$ keV, which differs significantly from the Particle Data Group's reported value of ${\Gamma }_{{\eta }_c\gamma \gamma }=5.4(4)$ keV (2.9~$\sigma$ tension). We provide insight into the comparison between our findings, previous theoretical predictions, and experimental measurements.

arXiv comment8 pages + 2 page supplemental material, 5 figures,4 tables. Published version by Science Bulletin

References in corpus (43)

• Rigorous QCD Analysis of Inclusive Annihilation and Production of Heavy Quarkonium
• Heavy quarkonium: progress, puzzles, and opportunities
• Quarkonium Wave Functions at the Origin
• Light Meson Physics from Maximally Twisted Mass Lattice QCD
• Pseudoscalar decay constants of kaon and D-mesons from Nf=2 twisted mass Lattice QCD
• Observation of eta_c^{prime} Production in gamma gamma Fusion at CLEO
• The low-lying baryon spectrum with two dynamical twisted mass fermions
• Lattice calculation of the pion transition form factor ${\pi }^0\to {\gamma }^{\ast }{\gamma }^{\ast }$
• Two Photon Decays of Charmonia from Lattice QCD
• Lattice QCD study of the radiative decays $J/\psi \to {\eta }_c\gamma$ and $h_c\to {\eta }_c\gamma$
• Charmonium properties from lattice QCD + QED: hyperfine splitting, $J/\psi$ leptonic width, charm quark mass and $a_{\mu }^c$
• First-principles calculation of electroweak box diagrams from lattice QCD
• First lattice calculation of radiative leptonic decay rates of pseudoscalar mesons
• QED self energies from lattice QCD without power-law finite-volume errors
• Can NRQCD explain the $\gamma {\gamma }^{\ast }\to {\eta }_c$ transition form factor data?
• Charm annihilation effects on the hyperfine splitting in charmonium
• Long-distance Contributions to Neutrinoless Double Beta Decay ${\pi }^{-}\to {\pi }^{+}ee$
• Lattice QCD calculation of the electroweak box diagrams for the kaon semileptonic decays
• Measurement of gamma gamma -> p p-bar production at Belle
• Next-to-next-to-leading-order QCD corrections to hadronic width of pseudoscalar quarkonium
• Lattice QCD calculation of the pion charge radius using a model-independent method
• Two-photon decay of the neutral pion in lattice QCD
• Observation of J/psi --> 3 gamma
• An estimate of the flavour singlet contributions to the hyperfine splitting in charmonium
• Contribution of disconnected diagrams to the hyperfine splitting of charmonium
• Lattice QCD Calculation of the Pion Mass Splitting
• Formation of the ${\eta }_c$ in Two-Photon Collisions at LEP
• Measurements of the Mass, total Width and Two-Photon Partila Width of the ${\eta }_c$ Meson
• Lattice QCD calculation of ${\pi }^0\to e^{+}{e}^{-}$ decay
• First study of η_c, η(1760) and X(1835) production via η'π^+π^- final states in two-photon collisions
• Lattice QCD calculation of the two-photon exchange contribution to the muonic-hydrogen Lamb shift
• Evidence for ${\eta }_c\to \gamma \gamma$ and Measurement of $J/\psi \to 3\gamma$
• Two Photon Decays of ${\eta }_c$ from Lattice QCD
• The Glueball content of ${\eta }_c$
• Spectra of heavy-light and heavy-heavy mesons containing charm quarks, including higher spin states for $N_f=2+1$
• Lattice QCD calculation of $K\to \ell {\nu }_{\ell }{\ell }^{\prime +}{\ell }^{\prime -}$ decay width
• Finite-volume effects in long-distance processes with massless leptonic propagators
• New puzzle in charmonium decays
• Lattice QCD calculation of light sterile neutrino contribution in $0\nu 2\beta$ decay
• Exclusive quarkonium production or decay in soft gluon factorization
• The eta_c(2980) formation in two-photon collisions at LEP energies
• Three Photon Decay of $J/\psi$ from Lattice QCD
• Measurements of the Absolute Branching Fractions of B^\pm --> K^\pm X_{c\bar c}

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• Improved evaluation of the electroweak contribution to muon $g-2$
• First lattice QCD calculation of $J/\psi$ semileptonic decay containing $D$ and $D_s$ particles
• Hadronic light-by-light scattering in the anomalous magnetic moments of electron and $\tau$
• Observation of the charmonium decay ${\eta }_c\to \gamma \gamma$ in $J/\psi \to \gamma {\eta }_c$
• Self-consistent analysis for the ${\eta }_c\to \gamma \gamma$ process
• Lattice study of $J/\psi \to \gamma {\eta }_c$ using a method without momentum extrapolation
• Study of the Magnetic Dipole Transition of $J/\psi \to \gamma {\eta }_c$ via ${\eta }_c\to p\bar{p}$
• Lattice determination of the neutrino background for $J/\psi \to \gamma +\text{invisible}$