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CLAS data now give the first virtual-photon polarization observables for π⁺π⁻p electroproduction, plus cleaner unpolarized cross sections ready for resonance electrocouplings.

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CLAS data yield nine improved single-differential and fully integrated π⁺π⁻p electroproduction cross sections plus first TT/LT polarization observables for 2–5 GeV² Q² and 1.4–2.125 GeV W.

T0 review reviewed 2026-07-10 challenge →

load-bearing objection Solid CLAS data paper that supersedes the 2017 unpolarized cross sections on the same set and adds the first TT/LT polarization observables for this channel; ready for electrocoupling work.

arxiv 2607.06793 v1 pith:P34M4AQP submitted 2026-07-07 nucl-ex

Measurements of $\gamma_v p \to \pi^+ \pi^- p'$ Cross Sections with the CLAS Detector for $Q^{2}$ from 2.0--5.0~GeV$^{2}$ and $W$ from 1.400--2.125~GeV

A. Trivedi , R.W. Gothe , E. Phelps , V.I. Mokeev , D.S. Carman , P. Achenbach , J. S. Alvarado , M.J. Amaryan
show 117 more authors
H. Atac H. Avakian N.A. Baltzell L. Barion M. Bashkanov M. Battaglieri F. Benmokhtar A. Bianconi A. Biselli M. Bondi F. Bossu S. Boiarinov K.-Th. Brinkmann W.J. Briscoe S. Bueltmann V.D. Burkert T. Cao R. Capobianco A. Celentano P. Chatagnon V. Chesnokov G. Ciullo P.L. Cole M. Contalbrigo V. Crede A. D'Angelo N. Dashyan R. De Vita A. Deur S. Diehl C. Dilks C. Djalali M. Dugger R. Dupre A. El Alaoui L. El Fassi L. Elouadrhiri S. Fegan A. Filippi G. Gavalian D.I. Glazier Y. Gotra L. Guo K. Hafidi H. Hakobyan M. Hattawy F. Hauenstein D. Heddle M. Hoballah M. Holtrop Yu-Chun Hung Y. Ilieva D.G. Ireland E.L. Isupov H. Jiang H.S. Jo V. Klimenko A. Kripko V. Kubarovsky L. Lanza P. Lenisa S. Liyanaarachchi I .J .D. MacGregor D. Marchand V. Mascagna D. Matamoros M. Maynes B. McKinnon T. Mineeva M. Mirazita C. Munoz Camacho P. Nadel-Turonski T. Nagorna K. Neupane S. Niccolai M. Osipenko P. Pandey M. Paolone L.L. Pappalardo R. Paremuzyan W. Phelps N. Pilleux S. Polcher Rafael Y. Prok T. Reed M. Ripani J. Ritman C. Salgado S. Schadmand A. Schmidt R.A. Schumacher M.B.C. Scott Y.G. Sharabian S. Shrestha D. Sokhan N. Sparveris M. Spreafico S. Stepanyan I.I. Strakovsky S. Strauch J.A. Tan N. Trotta R. Tyson M. Ungaro S. Vallarino L. Venturelli T. Vittorini E. Voutier Y. Wang U. Weerasinghe X. Wei M.H. Wood L. Xu N. Zachariou Z.W. Zhao V. Ziegler M. Zurek
This is my paper
classification nucl-ex PACS 13.40.-f13.40.Gp13.60.Le14.20.Gk
keywords CLASelectron scatteringexclusive meson productionnucleon resonance excitationsdouble-pion electroproductionvirtual-photon polarizationelectrocouplings
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper re-analyzes a large CLAS electron-scattering data set and extracts the nine single-differential and fully integrated cross sections for the reaction γ_v p → π⁺ π⁻ p' over a wide range of photon virtuality and hadronic energy. For the first time it also isolates the interference (TT and LT) pieces of the cross section that depend on the polarization of the virtual photon. The new extraction uses far more Monte-Carlo statistics and a cut on relative acceptance uncertainty that stabilizes the results and shrinks the systematic error tied to detector holes. Because the π⁺π⁻p channel is the only practical window on many higher-lying nucleon resonances, these cleaner observables are the essential input for determining how those resonances couple to a virtual photon as a function of distance scale.

Core claim

The nine unpolarized single-differential and fully integrated π⁺π⁻p electroproduction cross sections, together with the first measured TT and LT polarization-dependent observables, have been obtained with substantially improved accuracy and finer binning from the same CLAS data set previously analyzed in 2017, and are now ready for extraction of the γ_v p N* electrocouplings.

What carries the argument

The seven-dimensional sparse-histogram architecture that reconstructs yields, fills detector-blind kinematic holes by scaled Monte-Carlo, applies a relative-acceptance-uncertainty cut, and projects onto the nine one-fold and thirty polarization-dependent observables of the virtual-photon formalism.

Load-bearing premise

Yields inside detector-blind kinematic holes can be reliably recovered by scaling the Monte-Carlo event generator with a single global ratio taken from the non-hole bins.

What would settle it

An independent analysis of the same raw data that leaves the kinematic holes empty, or fills them with a qualitatively different generator, produces single-differential cross sections that disagree with the published hole-filled results outside the quoted systematics.

Watch this falsifier. Get emailed when new claim-graph text bears on it.

If this is right

  • Electrocouplings of all prominent N* states up to 1.8 GeV can now be extracted for Q² = 2–5 GeV² from this single exclusive channel.
  • The newly measured TT and LT interference terms supply direct constraints on the relative phases of resonant and non-resonant amplitudes.
  • The JM23 meson-baryon model already describes the nine unpolarized distributions without additional mechanisms, confirming that the included channels are sufficient in this kinematic domain.
  • Resonant and non-resonant contributions can be cleanly separated because their shapes differ markedly in the angular distributions.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same relative-acceptance-uncertainty cut can be ported to other multi-particle exclusive channels where simulation statistics have historically limited precision.
  • Once the electrocouplings are published, continuum Schwinger-method calculations of the same Q² evolution will face a sharper experimental benchmark in the transition from soft to hard QCD.
  • Machine-learning amplitude analyses trained on the full set of polarization observables may become feasible for the first time.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

0 major / 4 minor

Summary. The manuscript reports nine single-differential and fully integrated unpolarized cross sections for γ_v p → π⁺ π⁻ p′, together with the first extraction of the TT and LT photon-polarization-dependent observables, over 2.0 < Q² < 5.0 GeV² and 1.400 < W < 2.125 GeV from the CLAS e1-6a data set. The unpolarized results supersede the 2017 analysis of the same data through finer 5D binning, an order-of-magnitude increase in Monte-Carlo statistics, a demonstrated stability of the extracted cross sections versus MC sample fraction (Figs. 9–10), a relative-acceptance-uncertainty cut, and a quantified treatment of detector-blind kinematic holes. The observables are obtained from measured yields via the standard single-photon-exchange formalism (Eqs. 2–7); the JM23 model is used only for illustration of resonant/non-resonant contributions and is not required to define the reported cross sections.

Significance. These data constitute the only available high-Q² information on the nine independent single-differential and fully integrated π⁺ π⁻ p cross sections in the third-resonance region and above, and they supply the first TT/LT interference observables for this channel. The improved acceptance evaluation and reduced systematic uncertainty associated with simulation statistics directly strengthen the extraction of γ_v p N* electrocouplings for states with M > 1.55 GeV that cannot be reliably obtained from πN data alone. The results are already being used in a companion electrocoupling analysis and will remain a primary experimental input for continuum Schwinger and quark-model studies of the dressed-quark core versus meson-baryon cloud.

minor comments (4)
  1. In Section III H.3 and Fig. 11 the relative-acceptance-uncertainty cut of 0.65 is stated to be optimal, but a short quantitative statement of how the balance between hole-filling systematics and residual statistical fluctuations was evaluated (e.g., χ² or variance of the integrated cross section) would help readers reproduce the choice.
  2. Figure 17 caption and surrounding text compare the new results with Ref. [7] at one (Q², W) point; a brief remark on residual differences at the lowest W bins (where the 3π background and radiative tail are largest) would clarify the domain of supersession.
  3. Equation (7) mixes differentials “d” with bin-averaged quantities; the parenthetical remark that “Δ” would be more proper is helpful, but a consistent notation throughout Section II C would reduce ambiguity for readers implementing the formula.
  4. Table I lists the (Q², W)-averaged systematics; a sentence noting that the point-to-point values supplied with the CLAS Physics Database entries already incorporate the full covariance would be useful for subsequent amplitude analyses.

Circularity Check

0 steps flagged

No significant circularity: measured cross sections and polarization observables are extracted from yields via standard single-photon-exchange formalism and acceptance corrections; model fits are illustrative only.

full rationale

The paper reports experimental extractions of nine single-differential/fully integrated unpolarized cross sections plus the first TT/LT photon-polarization-dependent observables from CLAS ep o e'π+π-p' data. The 7D cross section (Eq. 7) is constructed directly from measured yields Δ^{7}N_ER, empty-target subtraction, luminosity, radiative factor R, and MC-derived acceptance A (with hole-filling Δ^{7}N_EH scaled by a global non-hole ratio). Polarization terms are obtained by projecting onto ϕ and fitting the known sinusoidal form of Eq. 6. Stability under MC statistics (Figs. 9–10) and a relative-acceptance cut (Fig. 11) are demonstrated empirically; systematics (Table I) are quantified, including 5.7% for hole-filling. The JM23 model is adjusted post-extraction only for illustration of resonant/non-resonant separation and is not used to define the reported observables. No step reduces a claimed prediction or first-principles result to its own inputs by construction, self-definition, or load-bearing self-citation of an unverified uniqueness claim. The derivation chain is the standard experimental pipeline and is self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

3 free parameters · 3 axioms · 0 invented entities

Experimental extraction rests on standard single-photon-exchange QED, the CLAS detector response model, and a set of analysis cuts whose systematic impact is quantified. No new dynamical entities are postulated; free parameters are limited to conventional cut thresholds and the global hole-filling scale factor.

free parameters (3)
  • relative acceptance uncertainty cut = 0.65
    Value 0.65 chosen after studying 0.50/0.65/0.95 to balance statistical fluctuations against hole-filling systematics (Section III H.3).
  • MM² cut window = [−0.04, 0.06] GeV²
    Nominal −0.04 to 0.06 GeV² optimized for signal-to-background; varied for systematics (Section III E).
  • hole-filling scale factor
    Global ratio of acceptance-corrected reconstructed to thrown MC yields used to populate detector-blind 7-D cells (Section III F.3).
axioms (3)
  • domain assumption Single-photon-exchange approximation factorizes the 7-D cross section into virtual-photon flux Γ_v and hadronic 5-D cross section (Eqs. 2–3).
    Standard for exclusive electroproduction analyses; higher-order QED corrections absorbed into the radiative factor R.
  • domain assumption CLAS GEANT3 simulation plus smearing reproduces detector acceptance and resolution sufficiently for efficiency evaluation.
    Validated by matching data/MC missing-mass and angular distributions; residual differences assigned 2 % systematic.
  • standard math Parity conservation forces sine coefficients of the ϕ expansion to vanish except when the projected variable is an α angle.
    Used to reduce the number of independent polarization observables (Section II B).

reviewed 2026-07-10 · how reviews work

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Cite this review

Pith. "Pith review of Measurements of $\gamma_v p \to \pi^+ \pi^- p'$ Cross Sections with the CLAS Detector for $Q^{2}$ from 2.0--5.0~GeV$^{2}$ and $W$ from 1.400--2.125~GeV." pith.science (2026). https://pith.science/paper/P34M4AQP

@misc{pith2026260706793,
  author       = {Pith},
  title        = {Pith review of: Measurements of $\gamma_v p \to \pi^+ \pi^- p'$ Cross Sections with the CLAS Detector for $Q^2$ from 2.0--5.0~GeV$^2$ and $W$ from 1.400--2.125~GeV},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/P34M4AQP}},
  note         = {Machine review of arXiv:2607.06793}
}
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abstract

Observables in the electroproduction of the $\pi^+\pi^-p$ reaction channel off the proton that are sensitive to the polarization of the virtual photon are presented for the first time in addition to the extraction of the nine single-differential and fully integrated cross sections within the kinematics area of 2.0~GeV$^2 < Q^2 < 5.0$~GeV$^2$ and 1.400~GeV $< W < 2.125$~GeV measured with the CLAS detector in Hall B at Jefferson Lab. The extraction of the unpolarized cross sections has been considerably improved in comparison with previously published results from this same dataset, offering finer binning over the five-dimensional hadronic reaction phase space, and including essential advances in the acceptance evaluation by implementing a new technique to stabilize the cross section extraction and minimize the systematic uncertainty associated with the simulation statistics. These improvements are of particular importance for the extraction of the $\gamma_v p N^*$ electrocouplings from these data.

Figures

Figures reproduced from arXiv: 2607.06793 by A. Bianconi, A. Biselli, A. Celentano, A. D'Angelo, A. Deur, A. El Alaoui, A. Filippi, A. Kripko, A. Schmidt, A. Trivedi, B. McKinnon, C. Dilks, C. Djalali, C. Munoz Camacho, C. Salgado, D.G. Ireland, D. Heddle, D.I. Glazier, D. Marchand, D. Matamoros, D.S. Carman, D. Sokhan, E.L. Isupov, E. Phelps, E. Voutier, F. Benmokhtar, F. Bossu, F. Hauenstein, G. Ciullo, G. Gavalian, H. Atac, H. Avakian, H. Hakobyan, H. Jiang, H.S. Jo, I.I. Strakovsky, I .J .D. MacGregor, J.A. Tan, J. Ritman, J. S. Alvarado, K. Hafidi, K. Neupane, K.-Th. Brinkmann, L. Barion, L. El Fassi, L. Elouadrhiri, L. Guo, L. Lanza, L.L. Pappalardo, L. Venturelli, L. Xu, M. Bashkanov, M. Battaglieri, M.B.C. Scott, M. Bondi, M. Contalbrigo, M. Dugger, M. Hattawy, M. Hoballah, M. Holtrop, M.H. Wood, M.J. Amaryan, M. Maynes, M. Mirazita, M. Osipenko, M. Paolone, M. Ripani, M. Spreafico, M. Ungaro, M. Zurek, N.A. Baltzell, N. Dashyan, N. Pilleux, N. Sparveris, N. Trotta, N. Zachariou, P. Achenbach, P. Chatagnon, P.L. Cole, P. Lenisa, P. Nadel-Turonski, P. Pandey, R.A. Schumacher, R. Capobianco, R. De Vita, R. Dupre, R. Paremuzyan, R. Tyson, R.W. Gothe, S. Boiarinov, S. Bueltmann, S. Diehl, S. Fegan, S. Liyanaarachchi, S. Niccolai, S. Polcher Rafael, S. Schadmand, S. Shrestha, S. Stepanyan, S. Strauch, S. Vallarino, T. Cao, T. Mineeva, T. Nagorna, T. Reed, T. Vittorini, U. Weerasinghe, V. Chesnokov, V. Crede, V.D. Burkert, V.I. Mokeev, V. Klimenko, V. Kubarovsky, V. Mascagna, V. Ziegler, W.J. Briscoe, W. Phelps, X. Wei, Y. Gotra, Y.G. Sharabian, Y. Ilieva, Y. Prok, Yu-Chun Hung, Y. Wang, Z.W. Zhao.

Figure 1
Figure 1. Figure 1: FIG. 1. Kinematic variables for the description of the re [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Distribution of the number of photoelectrons for a [PITH_FULL_IMAGE:figures/full_fig_p007_2.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. Illustration of the drift chamber based fiducial cuts [PITH_FULL_IMAGE:figures/full_fig_p008_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: FIG. 6 [PITH_FULL_IMAGE:figures/full_fig_p010_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: FIG. 7. Example [PITH_FULL_IMAGE:figures/full_fig_p010_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: shows the average 5D acceptance per (Q2 , W), labeled ⟨SA5 ⟩, computed in only those bins that are filled in the experimental data (labeled ⟨ER5 ⟩) using Eq. 16. (The corresponding figures for ⟨ST 5 ⟩ and ⟨SR5 ⟩ can be found in Ref. [36].) It is important to note that only the 5D acceptance in the experimentally filled phase space was required to estimate the true ex￾perimental yield. The simulation, howev… view at source ↗
Figure 9
Figure 9. Figure 9: FIG. 9. Single-differential cross sections [PITH_FULL_IMAGE:figures/full_fig_p013_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: FIG. 10. Single-differential cross sections [PITH_FULL_IMAGE:figures/full_fig_p014_10.png] view at source ↗
Figure 12
Figure 12. Figure 12: FIG. 12. Yield distribution in terms of [PITH_FULL_IMAGE:figures/full_fig_p015_12.png] view at source ↗
Figure 11
Figure 11. Figure 11: FIG. 11. Distribution of the acceptance [PITH_FULL_IMAGE:figures/full_fig_p015_11.png] view at source ↗
Figure 13
Figure 13. Figure 13: FIG. 13. Single differential cross sections for the representative ( [PITH_FULL_IMAGE:figures/full_fig_p016_13.png] view at source ↗
Figure 14
Figure 14. Figure 14: FIG. 14 [PITH_FULL_IMAGE:figures/full_fig_p017_14.png] view at source ↗
Figure 15
Figure 15. Figure 15: FIG. 15 [PITH_FULL_IMAGE:figures/full_fig_p018_15.png] view at source ↗
Figure 16
Figure 16. Figure 16: FIG. 16 [PITH_FULL_IMAGE:figures/full_fig_p019_16.png] view at source ↗
Figure 17
Figure 17. Figure 17: FIG. 17. Single-differential cross sections for a representative bin [PITH_FULL_IMAGE:figures/full_fig_p020_17.png] view at source ↗
Figure 18
Figure 18. Figure 18: FIG. 18. Description of the nine one-fold differential cross [PITH_FULL_IMAGE:figures/full_fig_p021_18.png] view at source ↗
Figure 19
Figure 19. Figure 19: FIG. 19. Resonant (red solid lines) and non-resonant (blue [PITH_FULL_IMAGE:figures/full_fig_p021_19.png] view at source ↗

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Reference graph

Works this paper leans on

48 extracted references · 48 canonical work pages

  1. [1]

    Mp′π+ , M π+π− , θ π− , ϕ π− , α [π−p][π+p′]

    work page

  2. [2]

    Mp′π+ , M p′π− , θ π+ , ϕ π+ , α [π+p][π−p′]

    work page

  3. [3]

    R” with “R2

    Mp′π+ , M π+π− , θ p′, ϕ p′, α [π+π−][pp′]. (1) The sets include the 3 di-hadron invariant mass com- binations (M p′π+,M π+π−,M p′π−), the 3 hadron CM polar angles (θπ−,θ π+,θ p′), the 3 hadron CM azimuthal angles (ϕπ−,ϕ π+,ϕ p′), defined as the angle between the electron scattering plane and the planes formed by the three-momenta of the final-state hadro...

    work page 2001

  4. [4]

    peaking approximation

    Radiative correction factorR. Radiative effects must be taken into account when determining an electroproduction cross section. To calculate the acceptance a MC event generator was employed that contained radiative effects, including photon emission from the initial and scattered electron, as well as soft loop corrections. The acceptance- corrected yield ...

    work page

  5. [5]

    The event selection includes a target vertex cut that included the 15-µm-thick target cell alu- minum endcap windows

    Empty-target correction factor ∆ 7Netgt ·Q ratio. The event selection includes a target vertex cut that included the 15-µm-thick target cell alu- minum endcap windows. To account for these events and remove them from the final yield, data from runs taken with an empty cryocell were em- ployed scaling the collected data to account for the relative luminosi...

    work page

  6. [6]

    Inaccessible kinematic holes ∆ 7NEH. In order to extract the integrated single-differential cross sec- tions, see Section II C, the fully differential (7D) cross sections and, hence, the experimental yields in all possible 7D bins, must be obtained. But not all of these 7D kinematic bins can be directly filled using the experimental data because the kinem...

    work page

  7. [7]

    Acceptance Calculation The acceptance was obtained from MC in each of the 7D bins of the analysis as the ratio of the total number of reconstructed events that survive all cuts to the total number of generated events as SA7 = SR7 ST 7 .(16) HereST 7,SR 7, andSA 7 are total the number of thrown events, the total number of reconstructed events that survive ...

    work page

  8. [8]

    Furthermore, electroproduction mea- surements have many more kinematic bins compared to photoproduction

    Required Level of Simulation Statistics In comparison to the two-particle final state of the single-meson electroproduction channel, the three- particle final state of the double-pion electroproduc- tion channel has a significantly larger and more com- plex phase space. Furthermore, electroproduction mea- surements have many more kinematic bins compared t...

    work page

  9. [9]

    These plots reveal two prominent features

    Relative Acceptance Uncertainty Cut Figure 11 shows the acceptanceSA 5 and its relative uncertainty for a representative (Q 2, W) bin. These plots reveal two prominent features. The distribution of the acceptance over all of the 5D bins has a peak at zero. Also, the distribution of the relative uncertainty shows several peaks above 0.5. Both features resu...

    work page

  10. [10]

    Achenbach, D

    P. Achenbach, D. S. Carman, R. W. Gothe, K. Joo, V. I. Mokeev, and C. D. Roberts, Symmetry17, 1106 (2025)

    work page 2025

  11. [11]

    D. S. Carman, R. W. Gothe, V. I. Mokeev, and C. D. Roberts, Particles6, 416 (2023)

    work page 2023

  12. [12]

    Burkert, G

    V. Burkert, G. Eichmann, and E. Klempt, Prog. Part. Nucl. Phys.146, 104214 (2026)

    work page 2026

  13. [13]

    V. I. Mokeev and D. S. Carman, Few Body Syst.63, 59 (2022)

    work page 2022

  14. [14]

    Ripaniet al.(CLAS Collaboration), Phys

    M. Ripaniet al.(CLAS Collaboration), Phys. Rev. Lett. 91, 022002 (2003)

    work page 2003

  15. [15]

    G. V. Fedotovet al.(CLAS Collaboration), Phys. Rev. C79, 015204 (2009)

    work page 2009

  16. [16]

    E. L. Isupovet al.(CLAS Collaboration), Phys. Rev. C96, 025209 (2017)

    work page 2017

  17. [17]

    G. V. Fedotovet al.(CLAS Collaboration), Phys. Rev. C98, 025203 (2018)

    work page 2018

  18. [18]

    V. I. Mokeev, P. Achenbach, V. D. Burkert, D. S. Car- man, R. W. Gothe, A. N. Hiller Blin, E. L. Isupov, K. Joo, K. Neupane, and A. Trivedi, Phys. Rev. C 108, 025204 (2023)

    work page 2023

  19. [19]

    V. I. Mokeevet al., Phys. Lett. B805, 135457 (2020)

    work page 2020

  20. [20]

    V. I. Mokeevet al., Phys. Rev.C93, 025206 (2016)

    work page 2016

  21. [21]

    V. I. Mokeev (CLAS Collaboration), Few Body Syst. 59, 46 (2018)

    work page 2018

  22. [22]

    I. G. Aznauryan and V. D. Burkert, Phys. Rev.C92, 015203 (2015)

    work page 2015

  23. [23]

    Parket al.(CLAS Collaboration), Phys

    K. Parket al.(CLAS Collaboration), Phys. Rev.C91, 045203 (2015)

    work page 2015

  24. [24]

    I. G. Aznauryan and V. D. Burkert, Prog. Part. Nucl. Phys.67, 1 (2012)

    work page 2012

  25. [25]

    Y.-F. Wang, M. D¨ oring, J. Hergenrather, M. Mai, T. Mart, U.-G. Meißner, D. R¨ onchen, and R. Work- man (J¨ ulich-Bonn-Washington), Phys. Rev. Lett.133, 101901 (2024)

    work page 2024

  26. [26]

    Kamano, S

    H. Kamano, S. X. Nakamura, T. S. H. Lee, and T. Sato, Phys. Rev. C94, 015201 (2016)

    work page 2016

  27. [27]

    Kamano, Few Body Syst.59, 24 (2018)

    H. Kamano, Few Body Syst.59, 24 (2018)

    work page 2018

  28. [28]

    A. N. Hiller Blinet al., Phys. Rev. C100, 035201 (2019)

    work page 2019

  29. [29]

    Segovia, C

    J. Segovia, C. Chen, Z. F. Cui, Y. Lu, and C. D. Roberts, AIP Conf. Proc.2249, 020010 (2020)

    work page 2020

  30. [30]

    M. Ding, C. D. Roberts, and S. M. Schmidt, Particles 6, 57 (2023)

    work page 2023

  31. [31]

    I. G. Aznauryan and V. D. Burkert, Phys. Rev.C85, 055202 (2012)

    work page 2012

  32. [32]

    I. G. Aznauryanet al., Int. J. Mod. Phys. E22, 1330015 (2013)

    work page 2013

  33. [33]

    I. G. Aznauryan and V. D. Burkert, Few Body Syst.59, 98 (2018)

    work page 2018

  34. [34]

    M. M. Giannini and E. Santopinto, Chin. J. Phys.53, 020301 (2015)

    work page 2015

  35. [35]

    Ramalho and D

    G. Ramalho and D. Melnikov, Phys. Rev. D97, 034037 (2018)

    work page 2018

  36. [36]

    Ramalho, Few Body Syst.59, 92 (2018)

    G. Ramalho, Few Body Syst.59, 92 (2018)

    work page 2018

  37. [37]

    Ramalho and M

    G. Ramalho and M. T. Pe˜ na, Prog. Part. Nucl. Phys. 136, 104097 (2024)

    work page 2024

  38. [38]

    Suzuki, T

    N. Suzuki, T. Sato, and T. S. H. Lee, Phys. Rev.C82, 045206 (2010)

    work page 2010

  39. [39]

    V. D. Burkert and C. D. Roberts, Rev. Mod. Phys.91, 011003 (2019)

    work page 2019

  40. [40]

    V. I. Mokeev and D. S. Carman, Acta Phys. Polon. B 57, 2 (2026)

    work page 2026

  41. [41]

    First Results on Nucleon Resonance Electroexcitation Amplitudes fromep→ e′π+π−p′ Cross Sections atWfrom 1.56–1.76 GeV and Q2 from 2.0–5.0 GeV 2,

    V. I. Mokeev, P. Achenbach, V. D. Burkert, D. S. Car- man, R. W. Gothe, E. L. Isupov, K. Joo, K. Neu- pane, and Y. Wunderlich, “First Results on Nucleon Resonance Electroexcitation Amplitudes fromep→ e′π+π−p′ Cross Sections atWfrom 1.56–1.76 GeV and Q2 from 2.0–5.0 GeV 2,” (2026), to be submitted in Phys. Rev. C

    work page 2026

  42. [42]

    Byckling and K

    E. Byckling and K. Kajantie,Particle Kinematics: (Chapters I-VI, X)(University of Jyvaskyla, Jyvaskyla, Finland, 1971)

    work page 1971

  43. [43]

    I. A. Skorodumina, V. D. Burkert, E. N. Golovach, R. W. Gothe, E. L. Isupov, B. S. Ishkhanov, V. I. Mo- keev, and G. V. Fedotov, Moscow University Physics Bulletin70, 429 (2015)

    work page 2015

  44. [44]

    Knochlein, D

    G. Knochlein, D. Drechsel, and L. Tiator, Z. Phys. A 352, 327 (1995)

    work page 1995

  45. [45]

    Trivedi and R

    A. Trivedi and R. W. Gothe,Measurement of New Observables from thepπ +π− Electroproduc- tion off the Proton - CLAS-Note 2026-001(2018), https://jlabdoc.jlab.org/docushare/dsweb/Get/ Document-307878/26-033.pdf

    work page 2026

  46. [46]

    B. A. Meckinget al., Nucl. Instrum. Meth. A503, 513 (2003)

    work page 2003

  47. [47]

    L. W. Mo and Y.-S. Tsai, Rev. Mod. Phys.41, 205 (1969)

    work page 1969

  48. [48]

    CLAS Physics Database,

    “CLAS Physics Database,”http://clasweb.jlab. org/physicsdb(2025)

    work page 2025

This paper was first reviewed by grok-4.5 on July 10, 2026.