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The $b\bar{b}c\bar{c}$ Fully Heavy Tetraquark at the LHC and the FCC: Multimodal Fragmentation and Observability

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João V. Bulhões, Francesco G. Celiberto, Victor P. Gonçalves

High Energy Physics - Phenomenology · Submitted 19 Oct 2026 · 176 references

Pith's verdict: Useful first fragmentation-function set for the X_{bbcc} tetraquark, but the scalar-diquark 'potentially accessible' claim rests on a Λ_D = 15 GeV choice that is not independently motivated.

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arXiv ID2610.27396 (version 1)
Pith IDCZOWKPT3, Pith's permanent record of this paper and its review
CitationFrancesco G. Celiberto, Jo\~ao V. Bulh\~oes, Victor P. Gon\c{c}alves. "The $b\bar{b}c\bar{c}$ Fully Heavy Tetraquark at the LHC and the FCC: Multimodal Fragmentation and Observability." arXiv:2610.27396 (2026). https://pith.science/paper/CZOWKPT3
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The paper

The paper claims

This paper constructs fragmentation functions for the all-heavy mixed-flavor bar b car c tetraquark and predicts that the direct-multiquark formation mechanism dominates over the scalar-diquark mechanism by roughly three orders of…

The reading

The paper aims to establish whether the yet-unobserved bar b car c tetraquark can be produced in sufficient numbers at present and future hadron colliders via fragmentation. It constructs two distinct microscopic formation mechanisms—direct multiquark fragmentation and sequential scalar-diquark fragmentation—and computes the corresponding fragmentation functions, evolved with DGLAP in a threshold-consistent scheme. The evolved functions are then embedded in a hybrid high-energy and collinear factorization framework to predict semi-inclusive X+jet production. The central finding is that the direct-multiquark mechanism is strongly favored, with predicted rates exceeding those from the diquark mode by about $10^{3}$. Nevertheless, the scalar-diquark mode still yields $10^{4}$ events at the HL-LHC and $10^{6}$ at the FCC, offering a potentially accessible alternative. The work thus provides a quantitative link between how the tetraquark is assembled and its observability.

What carries the argument

The TQ4Qhf1.0 set of collinear fragmentation functions for the bar b car c tetraquark, constructed from Suzuki-inspired initial conditions for both the direct-multiquark and scalar-diquark channels, evolved via DGLAP using the threshold-consistent Heavy-Flavor NonRelativistic evolution (HF-NRevo) scheme, and then embedded in the NLL/NLO+ HyF hybrid high-energy and collinear factorization framework for semi-inclusive X+jet production.

Extended reading notes

Core claim

The direct-multiquark fragmentation mechanism dominates the scalar-diquark mechanism by about three orders of magnitude in the integrated cross section for semi-inclusive bar b car c + jet production at the HL-LHC and FCC. This hierarchy originates from the distinctly different longitudinal-momentum profiles of the two fragmentation functions—direct fragmentation peaks around z~0.6, diquark around z~0.15–0.2—and persists through DGLAP evolution and high-energy resummation. At the nominal HL-LHC luminosity of 3 $ab^{{-1}}$, the direct mode yields ~4×$10^{7}$ produced tetraquarks, while the diquark mode yields ~1.7×$10^{4}$. At the FCC (20 $ab^{{-1}}$), these numbers rise to ~2.4×$10^{9}$ and ~1.7×$10^{6}$, respectively. The paper argues that these production-level statistics are encouraging for future searches, even though branching fractions and detector effects will reduce the detectable yields.

Load-bearing premise

The scalar-diquark form-factor scale Λ_D = 15 GeV, which enters the normalization of the diquark fragmentation function as $Λ_D^{4}$, has no independent determination for the mixed-flavor D(bc) diquark; adopting lower values (5–7 GeV) reduces the already suppressed diquark signal to near-negligible levels.

Editorial extensions

If this is right

  • At the HL-LHC with 3 ab^{-1}, the direct-multiquark mode yields about 4×10^7 produced tetraquarks, establishing a robust production baseline for experimental searches.
  • The scalar-diquark mode, though suppressed, yields about 1.7×10^4 events at the HL-LHC, meaning even a single measurement could distinguish the two mechanisms if experimental selection efficiently tags the jet.
  • At the FCC with 20 ab^{-1}, the yields reach 2.4×10^9 (direct) and 1.7×10^6 (diquark), providing a very strong lever arm for precision studies of tetraquark formation.
  • The rapidity-separation spectra for X+jet show similar shapes for the two mechanisms but widely separated normalizations, so the ratio of rates at different rapidity separations can serve as a discriminator.
  • The scalar-diquark mode exhibits a stronger energy scaling (factor ~15 from 14 to 100 TeV at fixed luminosity) than the direct mode (factor ~8.6), reflecting its softer fragmentation pattern, which could be tested by comparing yields at different collider energies.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If the X_{bar b car c} tetraquark is discovered, the ratio of its production rate in the X+jet channel vs. inclusive production, or as a function of transverse momentum, could be used to test which fragmentation scenario is realized in nature, rather than just confirming existence.
  • The strong dominance of the direct-multiquark mode implies that if no signal is seen at the predicted direct-mode rates, either the fragmentation model's parameters (like the transverse-momentum scale or the normalization) are too optimistic, or the tetraquark is too short-lived to be reconstructed; the diquark prediction provides a more conservative lower bound for null searches.
  • The framework can be extended to other mixed-flavor all-heavy tetraquarks (e.g., bar b car c with different J^{PC}, or bar b sar s) and to fully inclusive production without a tagged jet, which would further test the model's internal consistency.
Original abstract

We investigate the production of the all-heavy mixed-flavor $b\bar b c\bar c$ tetraquark through a multimodal fragmentation setup combining direct-multiquark and scalar-diquark mechanisms. Standard Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution is applied while preserving threshold consistency through the Heavy-Flavor NonRelativistic evolution (HF-NRevo) scheme. The resulting fragmentation functions (FFs) are then embedded into hybrid high-energy and collinear factorization at next-to-leading order for semi-inclusive tetraquark-plus-jet production. We compare the two mechanisms through rapidity-separation distributions at the 14 TeV High-Luminosity LHC (HL-LHC) and at the 100 TeV Future Circular Collider (FCC), finding a clear phenomenological preference for the direct-multiquark channel over the scalar-diquark mode. Integrated cross sections and expected event yields provide favorable production-level prospects for future searches at the HL-LHC, with substantially enhanced statistics at FCC energies. These results establish a quantitative connection between microscopic formation mechanisms and the prospective observability of the $b\bar b c\bar c$ tetraquark at present and future hadron colliders.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-10-21: 1 request, 5,226 input tokens.

What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.08 · human participants 0.01 · controlled comparison 0.29 · randomized assignment 0.01 · states quantitative result 0.32 · compares with prior results 0.79 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; .

We investigate the production of the all-heavy mixed-flavor $b\bar b c\bar c$ tetraquark through a multimodal fragmentation setup combining direct-multiquark and scalar-diquark mechanisms. Standard Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution is applied while preserving threshold consistency through the Heavy-Flavor NonRelativistic evolution (HF-NRevo) scheme. The resulting fragmentation functions (FFs) are then embedded into hybrid high-energy and collinear factorization at next-to-leading order for semi-inclusive tetraquark-plus-jet production. We compare the two mechanisms through rapidity-separation distributions at the 14 TeV High-Luminosity LHC (HL-LHC) and at the 100 TeV Future Circular Collider (FCC), finding a clear phenomenological preference for the direct-multiquark channel over the scalar-diquark mode. Integrated cross sections and expected event yields provide favorable production-level prospects for future searches at the HL-LHC, with substantially enhanced statistics at FCC energies. These results establish a quantitative connection between microscopic formation mechanisms and the prospective observability of the $b\bar b c\bar c$ tetraquark at present and future hadron colliders.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 We investigate the production of the all-heavy mixed-flavor $b\bar b c\bar c$ tetraquark through a multimodal fragmentation setup combining direct-multiquark and scalar-diquark mechanisms. contribution 0.95 0.89 0.06 asserted 0.93
s1 Standard Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution is applied while preserving threshold consistency through the Heavy-Flavor NonRelativistic evolution (HF-NRevo) scheme. method 1.00 0.68 0.02 asserted 0.99
s2 The resulting fragmentation functions (FFs) are then embedded into hybrid high-energy and collinear factorization at next-to-leading order for semi-inclusive tetraquark-plus-jet production. method 0.99 0.86 0.04 asserted 0.99
s3 We compare the two mechanisms through rapidity-separation distributions at the 14 TeV High-Luminosity LHC (HL-LHC) and at the 100 TeV Future Circular Collider (FCC), finding a clear phenomenological preference for the direct-multiquark channel over the scalar-diquark mode. result 1.00 0.95 0.57 asserted 1.00
s4 Integrated cross sections and expected event yields provide favorable production-level prospects for future searches at the HL-LHC, with substantially enhanced statistics at FCC energies. result 0.83 0.91 0.20 asserted 0.80
s5 These results establish a quantitative connection between microscopic formation mechanisms and the prospective observability of the $b\bar b c\bar c$ tetraquark at present and future hadron colliders. interpretation 1.00 0.87 0.63 asserted 1.00

What kind of paper the classifier reports this is: theoretical result 0.55 · evidence from simulation or computation 0.99.

What was examined, and what was not

sources read
  • arXiv listing abstract v1
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. Representative LO diagrams for the collinear fragmentation of a constituent charm
Figure 2. Representative LO diagrams for the collinear fragmentation of a constituent charm
Figure 3. Charm-initiated Xb¯bcc¯ FFs in the direct-multiquark mode (left) and scalar-diquark mode (right), shown as functions of z. Results are presented for µF = 40, 80, and 160 GeV. Solid curves denote the central predictions, while the shaded bands represent the corresponding uncertainty estimates. The lower panels display separately the F-MHOU and F-NPWF uncer￾tainty contributions, normalized to the central predictions. Nonperturbative uncertainties are instead estimated through F-NPWF variations of the transverse-momentum parameter ⟨⃗q 2 T ⟩, which controls the intrinsic momentum…
Figure 4. Bottom-initiated Xb¯bcc¯ FFs in the direct-multiquark mode (left) and scalar-diquark mode (right), shown as functions of z. Results are presented for µF = 40, 80, and 160 GeV. Solid curves denote the central predictions, while the shaded bands represent the corresponding uncertainty estimates. The lower panels display separately the F-MHOU and F-NPWF uncer￾tainty contributions, normalized to the central predictions. figurations encoding the F-MHOU and F-NPWF variations described above. We now turn to the phenomenological structure of the evolved FFs. Figures 3 and 4 display the…
Figure 5. Gluon-initiated Xb¯bcc¯ FFs in the direct-multiquark mode (left) and scalar-diquark mode (right), shown as functions of z. Results are presented for µF = 40, 80, and 160 GeV. Solid curves denote the central predictions, while the shaded bands represent the corresponding uncertainty estimates. The lower panels display separately the F-MHOU and F-NPWF uncer￾tainty contributions, normalized to the central predictions. Figures 3 and 4 reveal a clear separation between the direct-multiquark and scalar-diquark fragmentation patterns. For both charm- and bottom-initiated channels, the…
Figure 6. Diagrammatic sketch of the semi-inclusive hadroproduction of a
Figure 7. Predictions for the ∆Y -distributions of semi-inclusive Xb¯bcc¯ plus jet production in the direct-multiquark fragmentation mode at the 14 TeV HL-LHC (left) and the 100 TeV nominal FCC (right). Results are shown at NLL/NLO+, LL/LO, and HE-NLO+ accuracy. The upper panels display the total uncertainty bands, combining H-MHOU, F-MHOU, F￾NPWF, and numerical-integration uncertainties. The lower panels show, from top to bottom: a) the LL/LO- and HE-NLO+-to-NLL/NLO+ ratios, including H-MHOU variations only; b) the F-MHOU uncertainty band; and c) the F-NPWF uncertainty band, with the latter…
Figure 8. Predictions for the ∆Y -distributions of semi-inclusive Xb¯bcc¯ plus jet production in the scalar-diquark fragmentation mode at the 14 TeV HL-LHC (left) and the 100 TeV nominal FCC (right). Results are shown at NLL/NLO+, LL/LO, and HE-NLO+ accuracy. The upper panels display the total uncertainty bands, combining H-MHOU, F-MHOU, F-NPWF, and numerical-integration uncertainties. The lower panels show, from top to bottom: a) the LL/LO￾and HE-NLO+-to-NLL/NLO+ ratios, including H-MHOU variations only; b) the F-MHOU uncertainty band; and c) the F-NPWF uncertainty band, with the latter two…

Figures reproduced from arXiv:2610.27396 by the authors.

References

Discussion

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