{"id":"179e74cf-e90d-4f80-aa96-034b4bb5a0d5","arxiv_id":"2412.08045","paper_version":3,"verdict":"REJECT","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"high","formal_verification":"none","parameter_count":6,"one_line_summary":"A diquark fragmentation model predicts that photon-photon fusion at CEPC and ILC can produce the doubly charmed tetraquark Tcc with thousands of events per year.","lead":"This paper calculates how often the exotic doubly charmed tetraquark Tcc might be made when two photons collide at electron-positron machines like CEPC and ILC. It predicts thousands of events per year, but the estimate depends heavily on unmeasured hadronization inputs and on using the model in a kinematic region where the authors say it does not apply.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Integrated event rates are dominated by the low-pT region that the paper itself excludes from the model's validity, so the 'promising' observability claim rests on the neglected production mechanisms.","rationale":"The reader's REJECT is based on the same observation I find most load-bearing, and my reading agrees. The factorization of Eq. (5) is a model assumption, not a theorem; for it to be useful in making event-rate predictions, it must be applied in a kinematic region where the model is a good approximation. The paper itself stipulates that region to be large pT (Sec. II after Eq. (5)). However, the numerical predictions in Tables I-II integrate over low-pT-dominated ranges. The differential distributions in Figs. 3-4 make this concrete: at CEPC/ILC dσ/dpT decreases monotonically from low pT, so the integral is set by the 1-10 GeV region, far from the scaling region used to identify the fragmentation mechanism. At SuperKEKB the whole available pT range is small, so the model's stated validity condition is never met. The mass-dependence and hadronization-model uncertainties are secondary; even a factor of 40 spread cannot compensate for a mechanism that has been neglected where it would dominate. The proposed check is cheap: applying the same pT cuts used in the paper's own scaling fits to the total cross sections will show whether the 'promising' conclusion survives. I do not see a reason to soften the reader's verdict; REJECT (or at minimum 'unverified as written') is appropriate until the calculation is redone in the model's valid kinematic region.","tokens_in":15039,"tokens_out":4831,"duration_ms":49993,"concrete_test":"Recompute the CEPC and ILC cross sections in Table II with the pT lower cutoff raised to the lower edge of the scaling-fit windows used in Fig. 4 (10 GeV at CEPC, 20 GeV at ILC), and recompute SuperKEKB either with a large-pT cut or as an upper limit. If these restricted yields fall below a few events per year (or below the experimental sensitivity), the 'promising' conclusion is unsupported. A second, complementary check: vary the pT_min for CEPC/ILC from 1 to 10 GeV and quantify how much of the Table II rate comes from pT<10 GeV; if it is >90%, the quoted rate is controlled by the invalid region.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Sec. II (after Eq. (5)) states that the diquark-fragmentation contribution 'becomes dominant only in the large transverse momentum pt region' and that other mechanisms 'would dominate in the relatively small pt region'; the authors say these are neglected. Yet the integrated cross sections in Tables I-II integrate over pT ranges (SuperKEKB 0.2-4 GeV, CEPC 1-50 GeV, ILC 1-100 GeV) whose dominant contributions come from exactly the small-pT region. Fig. 4 shows dσ/dpT falling monotonically from the lower end of the range for both CEPC and ILC, and Fig. 3 has a mild bulge at 0.2-2 GeV; in all cases most of the rate is near the lower cutoff, not in the large-pT regime. The paper's own scaling fits use only 10<pT<50 GeV (CEPC) and 20<pT<100 GeV (ILC) to extract 1/pT^6 and 1/pT^4 shapes. No such cut is applied to the total cross sections, so the quoted yields (0.7-27)x10^3 at CEPC and (0.7-17)x10^4 at ILC are dominated by the neglected small-pT mechanisms. At SuperKEKB the entire pT window is low, so the model's validity condition fails throughout. This is an internal inconsistency in the central argument: the prediction is computed outside the regime where the model is claimed to apply.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript calculates inclusive production of the doubly charmed tetraquark Tcc in photon-photon fusion at SuperKEKB, CEPC, and ILC. It uses a diquark-fragmentation factorization, Eq. (5), in which a perturbatively produced (cc) diquark in the [3S1]_3bar or [1S0]_6 configuration subsequently hadronizes into Tcc with a model-dependent probability. Two hadronization schemes are compared: a harmonic oscillator potential (HOP) and a heavy diquark-antiquark symmetry (HDAS) fragmentation estimate. The paper reports total cross sections, transverse-momentum and angular distributions, and estimates event yields, concluding that Tcc observation at CEPC and ILC is promising.","tokens_in":15420,"tokens_out":15872,"duration_ms":159979,"significance":"If the factorization were valid over the integration ranges used, the paper would provide useful phenomenological estimates for Tcc searches at current and future e+e- colliders, complementing LHC studies. The manuscript is transparent in presenting the factorization ansatz, the two hadronization schemes, and explicit differential distributions, and it correctly identifies the high-pT scaling behavior (1/pT^6 at CEPC and 1/pT^4 at ILC) in the tails of the distributions. However, the central numerical claim is undermined by the paper's own validity condition for Eq. (5): the integrated cross sections are dominated by the low-pT region that the authors state is outside the model. Because the headline event yields are therefore not predictions of this model, the paper does not currently support its 'promising' conclusion.","major_comments":[{"comment":"The paper states that the diquark-fragmentation contribution of Eq. (5) 'becomes dominant only in the large transverse momentum pt region' and that other mechanisms 'would dominate in the relatively small pt region,' and that these other mechanisms are neglected. The total cross sections and event yields in Tables I-II and Sec. III are nevertheless obtained by integrating down to pT = 0.2 GeV at SuperKEKB and pT = 1 GeV at CEPC and ILC. The differential distributions in Figs. 3-4 fall monotonically from the lower end of the integration range, with only a mild bulge at 0.2-2 GeV at SuperKEKB, so the integrated rates are dominated by exactly the low-pT region that the model is claimed not to cover. At SuperKEKB the entire pT window 0.2-4 GeV lies in that region. Since the quoted yields of (0.7-27) x 10^3 at CEPC and (0.7-17) x 10^4 at ILC are therefore dominated by neglected mechanisms, the conclusion that 'the experimental study of Tcc at CEPC and ILC is promising' is not supported by the calculation; the authors need either to include the neglected mechanisms or to restrict the reported cross sections to the large-pT region and revise the conclusions accordingly.","section":null},{"comment":"The event rates quoted in the text are not clearly tied to the cross sections and the stated D0 decay branching. For example, with a standard 10^7-s year, the CEPC luminosity of 10^34 cm^-2 s^-1 gives 100 fb^-1, so the largest CEPC cross section in Table II (261.52 fb) yields about 2.6 x 10^4 events before any decay branching; multiplying by Br(D0 -> K- pi+)^2 = (3.95%)^2 reduces this to about 40 events per year. The text quotes (0.7-27) x 10^3 events at CEPC and then mentions the D0 branching fraction without stating whether the quoted yields include it. This ambiguity changes the strength of the 'promising' conclusion by orders of magnitude and must be resolved by stating exactly which numbers include reconstruction and branching.","section":null},{"comment":"The SuperKEKB yield estimate 'about 5 ~ 10^4 events of Tcc per year' is not reproducible from Table I. With L = 8 x 10^35 cm^-2 s^-1 and a 10^7-s year, the integrated luminosity is 8000 fb^-1; the cross sections in Table I range from 0.13 x 10^-3 fb to 134.94 x 10^-3 fb, giving roughly 1 to 1080 events per year. Even with a 3.15 x 10^7-s year the maximum is about 3400 events per year. The quoted upper value therefore appears to exceed the model's yield by an order of magnitude, and this discrepancy should be corrected and explained.","section":null}],"minor_comments":[{"comment":"There are several typographical errors: 'produciton' in the abstract, 'decompositron' in Sec. I, 'transver momentum' in Sec. III, 'Cornel potential' for Cornell potential, 'pow-low potential' for power-law potential, and 'The the long-distance' in Sec. II B.","section":null},{"comment":"The phrase 'the reconstruction of Tcc by D0D0pi+ with approximated 100%' is unclear: it should specify whether 100% refers to the detection efficiency for that channel, the branching fraction of Tcc into D0D0pi+, or something else.","section":null},{"comment":"The hadronization probabilities P in Eqs. (19)-(22) are written with units of GeV^3, while Eq. (5) presents them as multiplicative factors multiplying a differential cross section; the text should clarify the dimensional bookkeeping, i.e., how the GeV^3 factor is absorbed into the short-distance coefficient, so that the final cross section has standard units.","section":null},{"comment":"The lower end of the quoted CEPC yield range appears to sum the [1S0]6 and [3S1] HDAS cross sections for mc = 1.94 GeV, while the upper end uses only the [3S1] HOP cross section for mc = 1.5 GeV; the text should state explicitly how the quoted ranges are constructed from the table entries.","section":null},{"comment":"The labels '1/pt^6 line shape' and '1/pt^4 line shape' in Fig. 4 should state that these are fits to the last three data points of each curve, as described in the text; otherwise the reader may infer a global scaling behavior.","section":null}],"recommendation":"reject","confidential_remarks":"I recommend reject. The main conclusion is undermined by an internal inconsistency: the model's stated validity region excludes the low-pT domain that dominates the integrated cross sections, so the quoted yields are not predictions of the model as written. Fixing this would require either computing the neglected mechanisms or changing the paper's central claim, which is a substantial reworking. The event-rate arithmetic also needs correction. The paper may be salvageable as a study of the high-pT fragmentation contribution, but not as a prediction of total Tcc yields at these colliders."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Short version: the paper does a real calculation that hasn't been done before, and the authors are honest about their model's uncertainty. But the headline claim—that Tcc should be observable at CEPC and ILC—does not follow from their own numbers. They state that the diquark fragmentation contribution they calculate only becomes dominant at large transverse momentum, and that other, neglected mechanisms dominate at small pT. Then they integrate the total cross section from pT = 0.2 GeV (SuperKEKB) or 1 GeV (CEPC/ILC). The dsigma/dpT curves in Figs. 3–4 fall monotonically from the lower cutoff, so the integrated rates are built on exactly the region they told us the model does not cover. That is not a minor caveat; it is the load-bearing part of the observability claim.\n\nCredit where due: applying the diquark fragmentation model to photon-photon fusion for Tcc is new, covering both the [3S1]bar3 and [1S0]6 diquark channels. The authors also compare two hadronization schemes and show the resulting order-of-magnitude spread in rates, which is transparent. The large-pT scaling fits with 1/pT^6 and 1/pT^4 are a useful check on the underlying mechanism. That part of the analysis looks fine.\n\nWhere it goes soft: the internal inconsistency above is the main problem. The hadronization probabilities themselves are taken from outside sources and carry large uncertainty; the paper acknowledges this, but it means the central prediction is a range, not a benchmark. No code or data files accompany the 40-diagram calculation, so independent verification is not immediate. These are secondary to the pT issue, though.\n\nWho should read it: people who work on Tcc production mechanisms and lepton collider prospects. The paper is a reasonable starting point for a large-pT calculation, but as written it is not a reliable forecast of Tcc yields.\n\nFor peer review: I would not desk reject. The calculation is new, the flaw is clear and fixable, and a revision that applies a genuine large-pT cut—or adds the neglected low-pT mechanisms—would make the paper useful. As it stands, I would expect major revision.","headline":"A new gamma-gamma fusion calculation for Tcc that is undercut by its own kinematic caveat: the quoted event rates are dominated by the small-pT region the model explicitly says it does not cover.","tokens_in":15974,"tokens_out":3631,"would_cite":false,"duration_ms":36529,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"Under a diquark-fragmentation model, photon-photon fusion at future electron-positron colliders is predicted to produce the doubly charmed tetraquark Tcc in observable numbers.","keywords":["doubly charmed tetraquark","Tcc(3875)","photon-photon fusion","diquark fragmentation","electron-positron collider","CEPC","ILC","hadronization"],"falsifier":"A dedicated photon-photon run at SuperKEKB or CEPC/ILC that reconstructs $T_{cc}$ in the $D^0D^0\\pi^+$ channel and measures $d\\sigma/dp_t$ would settle the claim: the diquark-fragmentation model predicts a specific low-$p_t$ behavior, and a measured low-$p_t$ yield above that prediction would show that neglected direct hadronization contributes, invalidating the quoted rates as full predictions.","tokens_in":14795,"feed_emoji":"⚛️","tokens_out":10813,"duration_ms":100314,"temperature":0.7,"pith_summary":"This paper predicts that the doubly charmed tetraquark $T_{cc}$ — a state with quark content $cc\\bar u\\bar d$ — can be produced in photon-photon collisions at electron-positron machines in numbers large enough to study. The calculation treats production in two steps: a perturbative stage in which two photons create a heavy $(cc)$ diquark plus two charm antiquarks, and a nonperturbative stage in which the diquark hadronizes into the tetraquark. The spin-triplet color-antitriplet diquark configuration $(cc)[{}^3S_1]_{\\bar 3}$ dominates over the spin-singlet color-sextuplet $(cc)[{}^1S_0]_6$. Depending on the hadronization model and the assumed constituent charm mass, the expected yields are $5\\text{--}10^4$ events per year at SuperKEKB, $(0.7\\text{--}27.0)\\times10^3$ per year at CEPC, and $(0.7\\text{--}17.0)\\times10^4$ per year at ILC, leading the authors to conclude that CEPC and ILC could observe $T_{cc}$ in this channel. The result matters because a measured rate and spectrum would test how a colored diquark turns into an exotic hadron.","feed_headline":"Photon collisions could yield thousands of Tcc tetraquarks a year","feed_subtitle":"Diquark-fragmentation model projects up to 27,000 events yearly at CEPC and 170,000 at ILC.","key_machinery":"The machinery is the factored cross section $d\\sigma=\\int dx_1dx_2\\, f_\\gamma(x_1)f_\\gamma(x_2)\\,d\\hat\\sigma(\\gamma\\gamma\\to T_{cc}[n]+\\bar c+\\bar c)$, with $d\\hat\\sigma(\\gamma\\gamma\\to T_{cc}[n]+\\bar c+\\bar c)=d\\hat\\sigma(\\gamma\\gamma\\to(cc)[n]+\\bar c+\\bar c)\\,P((cc)[n]\\to T_{cc}[n])$. The photon fluxes are the Weizsäcker-Williams spectrum for SuperKEKB and CEPC and the laser-backscattering spectrum for ILC. The short-distance part is computed by transforming known charmonium production amplitudes through a charge-conjugation relation and applying the NRQCD diquark projector of Eq. (13), which puts the two charm quarks into the spin-singlet or spin-triplet color state. The long-distance factor is either the Schrödinger wave function at the origin from a harmonic-oscillator potential, giving $P((cc)[{}^3S_1]_{\\bar 3}\\to T_{cc})=0.089\\,\\mathrm{GeV}^3$, or the heavy-diquark-antiquark-symmetry estimate $|\\Psi_{cc}(0)|^2 f(c\\to\\Lambda_c^+)=0.00243\\,\\mathrm{GeV}^3$. These two hadronization probabilities are the main source of model dependence in the predicted yields.","core_discovery":"The paper's central claim is that $T_{cc}$ production in $\\gamma\\gamma$ fusion is calculable as the product of a perturbative short-distance cross section for producing a $(cc)[n]$ diquark and a long-distance hadronization probability $P((cc)[n]\\to T_{cc}[n])$, with the factorization written in Eqs. (1) and (5). The $(cc)[{}^3S_1]_{\\bar 3}$ configuration dominates, and under the harmonic-oscillator-potential hadronization scheme its cross section reaches hundreds of femtobarns at CEPC and ILC, translating into thousands of events per year. The heavy-diquark-antiquark-symmetry scheme, which uses the measured $c\\to\\Lambda_c^+$ fragmentation fraction, suppresses the hadronization probability to about 2.7% of the harmonic-oscillator value and lowers the yields correspondingly. The authors emphasize that the cross sections are sensitive to the constituent charm mass in the diquark and to the choice of hadronization model.","pith_inferences":["If the factorization survives comparison with data, the same $\\gamma\\gamma$ channel could be used to extract the $(cc)$-diquark wave function and the hadronization probability, turning $T_{cc}$ production into a quantitative probe of nonperturbative diquark dynamics.","Because the paper integrates over transverse-momentum ranges whose low end is dominated by mechanisms it neglects, the quoted yields are best read as the diquark-fragmentation contribution; measurements that separate low- and high-$p_t$ could quantify the missing direct-production component.","The same factorization machinery could be applied to other doubly heavy tetraquarks, such as $T_{bb}$, or to doubly heavy baryons in photon-photon collisions, giving a family of related predictions testable at future colliders."],"forward_implications":["The $(cc)[{}^3S_1]_{\\bar 3}$ diquark configuration dominates $T_{cc}$ production by more than an order of magnitude over $(cc)[{}^1S_0]_6$ in the same hadronization scheme, so spin-color selection is a clear prediction.","Lowering the assumed constituent charm mass from 1.94 GeV to 1.5 GeV increases the cross section by factors of roughly 2 to 6, with the largest effect near threshold, so the mass scheme must be pinned down before precise rate predictions are possible.","The HDAS hadronization scheme suppresses the $[{}^3S_1]_{\\bar 3}$ contribution by about a factor of 37 relative to the harmonic-oscillator scheme, meaning an event-rate measurement would discriminate between hadronization models.","The large-transverse-momentum spectrum scales as $1/p_t^6$ at CEPC and $1/p_t^4$ at ILC, indicating double-parton fragmentation in one case and single-parton fragmentation in the other; the turnover point is testable.","Counting rates reach $(0.7\\text{--}27.0)\\times10^3$ events per year at CEPC and $(0.7\\text{--}17.0)\\times10^4$ events per year at ILC, enough for a first $\\gamma\\gamma$ search for $T_{cc}$."],"supporting_citations":[{"why":"Reports the experimental discovery of Tcc, the state whose production is predicted.","marker":"[3, 4]"},{"why":"Supplies the harmonic-oscillator-potential hadronization probabilities used for the two Tcc diquark configurations.","marker":"[38]"},{"why":"Establishes the factorization approach in which doubly heavy hadron production is split into short-distance diquark production and long-distance hadronization.","marker":"[23]"},{"why":"Provides the two-step heavy-diquark-to-tetraquark hadronization scheme used in the HDAS estimate.","marker":"[30, 35]"},{"why":"Gives the measured charm-quark fragmentation fraction f(c -> Lambda_c^+) used in the HDAS hadronization probability.","marker":"[60]"},{"why":"Supplies the amplitude transformation that converts quarkonium production amplitudes into diquark production amplitudes.","marker":"[49]"},{"why":"Supplies the NRQCD formalism and projectors used to compute the short-distance coefficient.","marker":"[50]"},{"why":"Supplies the Weizsäcker-Williams equivalent-photon spectrum used for photon fluxes at SuperKEKB and CEPC.","marker":"[43-45]"},{"why":"Supplies the laser-backscattering photon spectrum used for the ILC calculation.","marker":"[47]"}],"fun_headline_variants":["Photon fusion yields up to 170k Tcc tetraquarks yearly at ILC","Photon-photon fusion could create 27k Tcc tetraquarks a year at CEPC","Photon fusion predicts 27k Tcc events at CEPC and 170k at ILC","Tcc tetraquark rate in photon collisions up to 170k per year at ILC"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The calculation assumes that the factorized diquark-fragmentation formula of Eq. (5) is the only production mechanism that matters over the entire transverse-momentum ranges integrated, although the paper itself says other mechanisms dominate at small $p_t$ where the cross section is largest.","fun_headline_variants_meta":{"raw":{"variants":["Photon fusion yields up to 170k Tcc tetraquarks yearly at ILC","Photon-photon fusion could create 27k Tcc tetraquarks a year at CEPC","Photon fusion predicts 27k Tcc events at CEPC and 170k at ILC","Tcc tetraquark rate in photon collisions up to 170k per year at ILC"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.001264,"raw_usage":{"total_tokens":5207,"prompt_tokens":1008,"completion_tokens":4199,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":624,"completion_tokens_details":{"reasoning_tokens":4097}},"tokens_in":624,"tokens_out":4199,"duration_ms":31113,"temperature":1.0,"reasoning_tokens":4097,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T18:17:15.791432+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A dedicated photon-photon run at SuperKEKB or CEPC/ILC that reconstructs $T_{cc}$ in the $D^0D^0\\pi^+$ channel and measures $d\\sigma/dp_t$ would settle the claim: the diquark-fragmentation model predicts a specific low-$p_t$ behavior, and a measured low-$p_t$ yield above that prediction would show that neglected direct hadronization contributes, invalidating the quoted rates as full predictions.","supporting_citations":[{"cited_title":"Doubly heavy hadrons and the domain of validity of doubly heavy diquark-anti-quark symmetry,","cited_arxiv_id":null,"evidence_quote":"Gives the measured charm-quark fragmentation fraction f(c -> Lambda_c^+) used in the HDAS hadronization probability."},{"cited_title":"Problems of Obtaining γγ and γϵ Colliding Beams at Linear Colliders,","cited_arxiv_id":null,"evidence_quote":"Supplies the amplitude transformation that converts quarkonium production amplitudes into diquark production amplitudes."},{"cited_title":"Doubly Heavy Baryon Production at A High Luminosity $e^+ e^-$ Collider","cited_arxiv_id":"1208.3051","evidence_quote":"Supplies the NRQCD formalism and projectors used to compute the short-distance coefficient."},{"cited_title":"Evidence for Colour-Octet Mechanism from CERN LEP2 gamma gamma -> J/psi + X Data","cited_arxiv_id":"hep-ph/0112259","evidence_quote":"Supplies the laser-backscattering photon spectrum used for the ILC calculation."}],"review_version":1}