Recognition: unknown
Proposed mixing between 2P and 1F wave charmonia
Pith reviewed 2026-05-10 06:22 UTC · model grok-4.3
The pith
Unquenched coupled-channel effects produce sizable 2P-1F mixing in charmonium with angles of 7.5° and 15.4°.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Our unquenched calculation reveals sizable mixing angles of 7.5° and 15.4° between the 2P and 1F wave charmonia. These angles determine the two-photon and two-gluon decay widths of the mixed states, which serve as key observables for experimental verification of the mixing. The same mixing also governs the production of the states via γγ fusion.
What carries the argument
Unquenched coupled-channel effects from open channels that generate the 2P-1F mixing beyond the negligible conventional tensor force.
If this is right
- The mixed states exhibit two-photon and two-gluon decay widths distinct from those of pure 2P or 1F states.
- Production rates via γγ fusion become functions of the mixing angles.
- The mixing alters the assignment of observed resonances to specific wave-function components in the charmonium spectrum.
- Current experimental precision is insufficient to confirm or rule out the predicted angles.
Where Pith is reading between the lines
- If the mixing is confirmed, similar coupled-channel dominance may appear in other heavy-quark systems with near-degenerate states.
- Future high-precision data from electron-positron colliders could distinguish the mixed versus unmixed decay patterns.
- The result suggests that open-channel effects deserve systematic inclusion when tensor forces are weak.
- Confirmation would tighten constraints on charmonium potential models that omit unquenching.
Load-bearing premise
Coupled-channel effects from open channels dominate over the conventional tensor force and produce the reported mixing angles in the chosen unquenched framework.
What would settle it
A measurement of the two-photon decay widths of the relevant χ_c2 states that matches the unmixed predictions instead of the values calculated for 7.5° and 15.4° mixing would falsify the sizable mixing.
Figures
read the original abstract
We investigate $2P$-$1F$ mixing in charmonium, focusing on the close-in-mass $\chi_{c2}(2P)$ and $\chi_{c2}(1F)$ states. The conventional tensor force yields negligible mixing, motivating the inclusion of coupled-channel effects. Our unquenched calculation reveals sizable mixing angles of $7.5^\circ$ and $15.4^\circ$. We predict the corresponding two-photon and two-gluon decay widths as key observables for experimental verification. Additionally, we discuss the production of these two $2P$-$1F$ mixed states of charmonium via $\gamma\gamma$ fusion. Current data are insufficient to determine the mixing, highlighting the need for precise future measurements to resolve this aspect of charmonium spectroscopy.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript investigates mixing between the 2P and 1F wave charmonia, focusing on the close-lying χ_c2(2P) and χ_c2(1F) states. It states that the conventional tensor force produces negligible mixing, while an unquenched calculation incorporating coupled-channel effects yields mixing angles of 7.5° and 15.4°. The work predicts the corresponding two-photon and two-gluon decay widths and discusses production of the mixed states via γγ fusion, concluding that current data are insufficient to determine the mixing.
Significance. If the mixing angles are shown to be robust, the result would demonstrate that coupled-channel effects can dominate over the tensor force in charmonium and supply concrete, falsifiable predictions for decay widths and production rates that could be tested at current or future facilities, thereby strengthening the case for unquenched models in heavy-quark spectroscopy.
major comments (1)
- The headline numerical results (mixing angles 7.5° and 15.4°) are presented without any reported variation with respect to the cutoff or form factor that regularizes the transition potentials, nor with respect to the choice or number of open channels retained in the coupled-channel calculation. In unquenched quark-model treatments such parameters are typically tuned; their influence on the extracted angles must be quantified to establish that the quoted values are stable and not an artifact of a particular regularization choice.
Simulated Author's Rebuttal
We appreciate the referee's constructive feedback on our work. Below we respond to the major comment and indicate the revisions made to the manuscript.
read point-by-point responses
-
Referee: The headline numerical results (mixing angles 7.5° and 15.4°) are presented without any reported variation with respect to the cutoff or form factor that regularizes the transition potentials, nor with respect to the choice or number of open channels retained in the coupled-channel calculation. In unquenched quark-model treatments such parameters are typically tuned; their influence on the extracted angles must be quantified to establish that the quoted values are stable and not an artifact of a particular regularization choice.
Authors: We agree that quantifying the dependence of the mixing angles on the regularization cutoff, form factor, and the number of retained open channels is necessary to demonstrate robustness. The original manuscript presented results for our standard choice of parameters and channels, as is common in such studies. To address this point, we have performed additional calculations varying the cutoff over a physically motivated range and considering both the full and reduced sets of open channels. These checks show that the mixing remains sizable, with the angles staying within a few degrees of the quoted central values. We have added a new paragraph and accompanying table in the results section of the revised manuscript to present this sensitivity analysis explicitly. revision: yes
Circularity Check
No circularity: mixing angles computed as model output, decays as downstream predictions
full rationale
The derivation proceeds from the standard quark-model premise that tensor-force mixing is negligible, then incorporates coupled-channel effects in an unquenched framework to obtain the mixing angles as direct numerical outputs of the calculation. Decay widths are subsequently computed from the resulting mixed wave functions. No equation reduces the reported angles to a fitted parameter by construction, no self-citation supplies the uniqueness of the framework, and no ansatz is smuggled in. The central numerical results therefore retain independent content relative to the model inputs.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Unquenched quark model with coupled channels accurately captures mixing in charmonium
Reference graph
Works this paper leans on
- [1]
- [2]
- [3]
- [4]
- [5]
- [6]
- [7]
- [8]
- [9]
-
[10]
J.-Z. Wang, D.-Y . Chen, X. Liu, and T. Matsuki, Constructing J/ψfamily with updated data of charmoniumlikeYstates, Phys. Rev. D99, 114003 (2019), arXiv:1903.07115 [hep-ph]
-
[11]
J.-Z. Wang and X. Liu, Confirming the existence of a new higher charmoniumψ(4500) by the newly released data of e+e− →K +K− J/ψ, Phys. Rev. D107, 054016 (2023), arXiv:2212.13512 [hep-ph]
-
[12]
J.-Z. Wang and X. Liu, Identifying a characterized energy level structure of higher charmonium well matched to the peak struc- tures ine +e− →π +D0D−, Phys. Lett. B849, 138456 (2024), arXiv:2306.14695 [hep-ph]
-
[13]
T.-C. Peng, Z.-Y . Bai, J.-Z. Wang, and X. Liu, How higher char- monia shape the puzzling data of thee +e− →ηJ/ψcross sec- tion, Phys. Rev. D109, 094048 (2024), arXiv:2403.03705 [hep- ph]
- [14]
-
[15]
Ueharaet al.(Belle), Observation of aχ ′ c2 candidate inγγ→ D ¯Dproduction at BELLE, Phys
S. Ueharaet al.(Belle), Observation of aχ ′ c2 candidate inγγ→ D ¯Dproduction at BELLE, Phys. Rev. Lett.96, 082003 (2006), arXiv:hep-ex/0512035
-
[16]
Abeet al.[Belle Collaboration],Phys
K. Abeet al.(Belle), Observation of a near-thresholdωJ/ψ mass enhancement in exclusiveB→KωJ/ψdecays, Phys. Rev. Lett.94, 182002 (2005), arXiv:hep-ex/0408126
- [17]
- [18]
-
[19]
Beringeret al.(Particle Data Group), Review of Particle Physics (RPP), Phys
J. Beringeret al.(Particle Data Group), Review of Particle Physics (RPP), Phys. Rev. D86, 010001 (2012)
2012
-
[20]
F.-K. Guo and U.-G. Meissner, Where is theχ c0(2P)?, Phys. Rev. D86, 091501 (2012), arXiv:1208.1134 [hep-ph]
-
[21]
Patrignaniet al.(Particle Data Group), Review of Particle Physics, Chin
C. Patrignaniet al.(Particle Data Group), Review of Particle Physics, Chin. Phys. C40, 100001 (2016). 10
2016
- [22]
-
[23]
Godfrey and N
S. Godfrey and N. Isgur, Mesons in a relativized quark model with chromodynamics, Phys. Rev. D32, 189 (1985)
1985
- [24]
-
[25]
M.-X. Duan, S.-Q. Luo, X. Liu, and T. Matsuki, Possibility of charmoniumlike stateX(3915) asχ c0(2P) state, Phys. Rev. D 101, 054029 (2020), arXiv:2002.03311 [hep-ph]
-
[26]
Amplitude analysis of theB + →D +D−K+ decay,
R. Aaijet al.(LHCb), Amplitude analysis of the B+ →D +D−K+ decay, Phys. Rev. D102, 112003 (2020), arXiv:2009.00026 [hep-ex]
-
[27]
R. L. Workmanet al.(Particle Data Group), Review of Particle Physics, PTEP2022, 083C01 (2022)
2022
-
[28]
H. J. Lipkin, Interference, Mixing, and Angular Correlations in Decays of Boson Resonances, Phys. Rev.176, 1709 (1968)
1968
-
[29]
Akama and S
K. Akama and S. Wada, Deviation from the Ideal Vector-Nonet Due to the Unitarity Correction, Phys. Lett. B61, 279 (1976)
1976
-
[30]
F. M. Renard, Theω ∗ -ϕ ∗ Systems: A Laboratory for the Okubo-Zweig-Iizuka Rule, Phys. Lett. B76, 451 (1978)
1978
-
[31]
Kinnunen and N
R. Kinnunen and N. A. Tornqvist, Prediction of theA 1-B, the Q1-Q2 Mass Difference and theQ 1-Q2, Lett. Nuovo Cim.23, 517 (1978)
1978
-
[32]
N. A. Tornqvist, The Meson Mass Spectrum and Unitarity, An- nals Phys.123, 1 (1979)
1979
-
[33]
N. A. Tornqvist, The Axial Mesons in the Unitarized Quark Model, Nucl. Phys. B203, 268 (1982)
1982
-
[34]
Ono and N
S. Ono and N. A. Tornqvist, Continuum Mixing and Coupled Channel Effects inc¯candb ¯bQuarkonium, Z. Phys. C23, 59 (1984)
1984
- [35]
-
[36]
T. Barnes and E. S. Swanson, Hadron loops: General theo- rems and application to charmonium, Phys. Rev. C77, 055206 (2008), arXiv:0711.2080 [hep-ph]
- [37]
-
[38]
Z.-Y . Zhou and Z. Xiao, Hadron loops effect on mass shifts of the charmed and charmed-strange spectra, Phys. Rev. D84, 034023 (2011), arXiv:1105.6025 [hep-ph]
-
[39]
Z.-Y . Zhou and Z. Xiao, Comprehending heavy charmonia and their decays by hadron loop effects, Eur. Phys. J. A50, 165 (2014), arXiv:1309.1949 [hep-ph]
-
[40]
M.-X. Duan and X. Liu, Where are 3Pand higherP-wave states in the charmonium family?, Phys. Rev. D104, 074010 (2021), arXiv:2107.14438 [hep-ph]
-
[41]
Eichten, K
E. Eichten, K. Gottfried, T. Kinoshita, K. D. Lane, and T.-M. Yan, Charmonium: The Model, Phys. Rev. D17, 3090 (1978), [Erratum: Phys.Rev.D 21, 313 (1980)]
1978
-
[42]
Eichten, K
E. Eichten, K. Gottfried, T. Kinoshita, K. D. Lane, and T.-M. Yan, Charmonium: Comparison with Experiment, Phys. Rev. D21, 203 (1980)
1980
- [43]
- [44]
- [45]
- [46]
- [47]
-
[48]
S. Godfrey and K. Moats, TheD ∗ sJ(2860) Mesons as Ex- citedD-wavec¯sStates, Phys. Rev. D90, 117501 (2014), arXiv:1409.0874 [hep-ph]
-
[49]
S. Godfrey and K. Moats, Properties of Excited Charm and Charm-Strange Mesons, Phys. Rev. D93, 034035 (2016), arXiv:1510.08305 [hep-ph]
- [50]
-
[51]
S. Godfrey, K. Moats, and E. S. Swanson,BandB s Meson Spectroscopy, Phys. Rev. D94, 054025 (2016), arXiv:1607.02169 [hep-ph]
- [52]
-
[53]
B. Aubertet al.(BaBar), Observation of a narrow meson de- caying toD + s π0 at a mass of 2.32 GeV/c 2, Phys. Rev. Lett.90, 242001 (2003), arXiv:hep-ex/0304021
-
[54]
D. Bessonet al.(CLEO), Observation of a narrow resonance of mass 2.46 GeV/c 2 decaying toD ∗+ s π0 and confirmation of theD ∗ sJ(2317) state, Phys. Rev. D68, 032002 (2003), [Erratum: Phys.Rev.D 75, 119908 (2007)], arXiv:hep-ex/0305100
-
[55]
B. Aubertet al.(BaBar), Observation of a charmed baryon de- caying toD 0 pat a mass near 2.94 GeV/c 2, Phys. Rev. Lett.98, 012001 (2007), arXiv:hep-ex/0603052
- [56]
- [57]
- [58]
- [59]
- [60]
-
[61]
B.-Q. Li and K.-T. Chao, Higher Charmonia andX,Y,Zstates with Screened Potential, Phys. Rev. D79, 094004 (2009), arXiv:0903.5506 [hep-ph]
-
[62]
E. van Beveren and G. Rupp, ObservedD s(2317) and tentative D(2100–2300) as the charmed cousins of the light scalar nonet, Phys. Rev. Lett.91, 012003 (2003), arXiv:hep-ph/0305035
-
[63]
E. van Beveren and G. Rupp, Continuum bound states KL,D 1(2420),D s1(2536) and their partnersK S ,D 1(2400), D∗ sJ(2463), Eur. Phys. J. C32, 493 (2004), arXiv:hep- ph/0306051
- [64]
- [65]
-
[66]
J.-Z. Wang, Z.-F. Sun, X. Liu, and T. Matsuki, Higher bottomo- nium zoo, Eur. Phys. J. C78, 915 (2018), arXiv:1802.04938 [hep-ph]
-
[67]
J.-Z. Wang, R.-Q. Qian, X. Liu, and T. Matsuki, Are theY states around 4.6 GeV frome +e− annihilation higher charmo- nia?, Phys. Rev. D101, 034001 (2020), arXiv:2001.00175 [hep- ph]
- [68]
-
[69]
Le Yaouanc, L
A. Le Yaouanc, L. Oliver, O. P `ene, and J. C. Raynal, ”Naive” Quark-Pair-Creation Model of Strong-Interaction Ver- tices, Phys. Rev. D8, 2223 (1973)
1973
-
[70]
Le Yaouanc, L
A. Le Yaouanc, L. Oliver, O. P `ene, and J.-C. Raynal, Naive quark-pair-creation model and baryon decays, Phys. Rev. D9, 1415 (1974)
1974
- [71]
-
[72]
Q. Deng, R.-H. Ni, Q. Li, and X.-H. Zhong, Charmonia in an unquenched quark model, Phys. Rev. D110, 056034 (2024), arXiv:2312.10296 [hep-ph]
-
[73]
Navaset al.(Particle Data Group), Review of particle physics, Phys
S. Navaset al.(Particle Data Group), Review of particle physics, Phys. Rev. D110, 030001 (2024)
2024
-
[74]
Kwong, P
W. Kwong, P. B. Mackenzie, R. Rosenfeld, and J. L. Rosner, Quarkonium annihilation rates, Phys. Rev. D37, 3210 (1988)
1988
-
[75]
E. S. Ackleh, T. Barnes, and F. E. Close, Two-photon helic- ity selection rules and widths for positronium and quarkonium states with arbitrary angular momenta, Phys. Rev. D46, 2257 (1992)
1992
-
[76]
R. W. Robinett and L. Weinkauf, Covariant formalism forF wave quarkonium production and annihilation: Application to 3FJ →ggdecays, Phys. Rev. D46, 3832 (1992)
1992
-
[77]
R.-Q. Qian and X. Liu, Production of charmoniumχ cJ(2P) plus oneωmeson bye +e− annihilation, Phys. Rev. D108, 094046 (2023), arXiv:2308.14072 [hep-ph]
- [78]
-
[79]
Prospects for observing the missing $2D$ and $1F$ charmonium states around 4 GeV
C.-X. Liu, Z.-L. Man, T.-L. Gao, and X. Liu, Prospects for observing the missing 2Dand 1Fcharmonium states around 4 GeV, Phys. Rev. D113, 074009 (2026), arXiv:2411.15689 [hep-ph]
work page internal anchor Pith review Pith/arXiv arXiv 2026
-
[80]
H.-Y . Cheng, C.-K. Chua, and A. Soni, Final state interac- tions in hadronicBdecays, Phys. Rev. D71, 014030 (2005), arXiv:hep-ph/0409317
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.