Manifestation of quark effects in nuclei via bremsstrahlung analysis in the proton-nucleus scattering

01506-000 S\~ao Paulo; 03680; 2); (2) Institute for Nuclear Research; (3) Laborat\'orio de F\'isica Te\'orica e Computacional - LFTC; (4) Department of Physics; (5) School of Physics; Astronomy; Brazil; China

arxiv: 2506.15254 · v1 · pith:ICBTDI2Jnew · submitted 2025-06-18 · ⚛️ nucl-th · hep-ph· nucl-ex

Manifestation of quark effects in nuclei via bremsstrahlung analysis in the proton-nucleus scattering

Sergei P. Maydanyuk (1 , 2) , K. Tsushima (3) , G. Ramalho (4) , Peng-Ming Zhang (5) ((1) Southern Center for Nuclear-Science Theory (SCNT) , Institute of Modern Physics , Chinese Academy of Sciences , Huizhou

show 22 more authors

China (2) Institute for Nuclear Research National Academy of Sciences of Ukraine Kyiv 03680 Ukraine (3) Laborat\'orio de F\'isica Te\'orica e Computacional - LFTC Programa de P\'osgradua\c{c}\~ao em Astrof\'isica e F\'isica Computacional Universidade Cidade de S\~ao Paulo 01506-000 S\~ao Paulo S\~ao Paulo Brazil (4) Department of Physics OMEG Institute Soongsil University Seoul Republic of Korea (5) School of Physics Astronomy Sun Yat-Sen University Zhuhai China)

This is my paper

Pith reviewed 2026-05-21 23:58 UTC · model grok-4.3

classification ⚛️ nucl-th hep-phnucl-ex

keywords bremsstrahlungquark effectsnucleon magnetic momentsQMC modelproton-nucleus scatteringincoherent emissionlight nucleicarbon isotopes

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The pith

Quark effects in nuclei produce detectable differences in bremsstrahlung spectra, clearest in ratios for light carbon isotopes.

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

The paper tries to establish that the quark structure of nucleons leads to enhanced magnetic moments inside nuclei, which in turn create measurable changes in the photons emitted during proton-nucleus collisions. It extends an existing bremsstrahlung calculation by adding these in-medium modifications from the quark-meson coupling model, calibrates the baseline version to TAPS data on gold, and then compares results with and without the quark contribution. The differences are small in heavy nuclei but become clear when ratios are taken between the spectra for 18C and 12C. A sympathetic reader would care because this supplies the first concrete, experimentally accessible signal for quark effects inside ordinary nuclei.

Core claim

After calibrating the bremsstrahlung model to TAPS data for p + 197Au without quark effects, inclusion of the QMC-predicted enhancement of nucleon magnetic moments produces slight differences in the calculated spectra, and these differences become clearly visible in the ratios of spectra between 18C and 12C.

What carries the argument

In-medium enhancement of nucleon magnetic moments predicted by the quark-meson coupling model, which increases the incoherent bremsstrahlung yield in proton-nucleus scattering.

If this is right

Quark effects remain too small to observe in middle and heavy nuclei because incoherent contributions dominate there.
Among carbon isotopes, 18C has the smallest incoherent contribution, so quark effects are least masked in that case.
Ratios of bremsstrahlung spectra between 18C and 12C amplify the quark-induced difference enough for experimental detection.
The same calibrated model provides a quantitative baseline for predicting the size of the effect in other light nuclei.

Where Pith is reading between the lines

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

Future bremsstrahlung measurements on light nuclei could serve as a direct test of in-medium quark models without requiring new theoretical machinery.
The same sensitivity to magnetic moments might allow the approach to be applied to other photon-emitting reactions to cross-check medium modifications.
If the predicted ratio difference is confirmed, it would strengthen the case for using bremsstrahlung as a probe of nucleon substructure in the nuclear environment.

Load-bearing premise

The bremsstrahlung model calibrated to data without quark effects remains accurate enough that adding only the QMC magnetic-moment enhancement produces a detectable and unambiguous difference in the spectra.

What would settle it

An experimental measurement of the bremsstrahlung spectrum ratio for proton scattering on 18C versus 12C that matches the calculation without the in-medium magnetic-moment enhancement.

Figures

Figures reproduced from arXiv: 2506.15254 by 01506-000 S\~ao Paulo, 03680, 2), (2) Institute for Nuclear Research, (3) Laborat\'orio de F\'isica Te\'orica e Computacional - LFTC, (4) Department of Physics, (5) School of Physics, Astronomy, Brazil, China, China), Chinese Academy of Sciences, G. Ramalho (4), Huizhou, Institute of Modern Physics, K. Tsushima (3), Kyiv, National Academy of Sciences of Ukraine, OMEG Institute, Peng-Ming Zhang (5) ((1) Southern Center for Nuclear-Science Theory (SCNT), Programa de P\'osgradua\c{c}\~ao em Astrof\'isica e F\'isica Computacional, Republic of Korea, S\~ao Paulo, Seoul, Sergei P. Maydanyuk (1, Soongsil University, Sun Yat-sen University, Ukraine, Universidade Cidade de S\~ao Paulo, Zhuhai.

**Figure 2.** Figure 2: FIG. 2: (Color online) Panel (a): Calculated bremsstrahlun [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗

read the original abstract

\textbf{Background} (1) The incoherent emission of photons is dominant comparing to coherent one in proton-nucleus scattering. The incoherent bremsstrahlung is very sensitive to the magnetic moments of nucleons in nuclei. (2) According to the quark-meson coupling (QMC) model, the nucleon magnetic moments in nuclei are enhanced relative to those in vacuum, originating from the quark structure of nucleons. \textbf{Purpose} Investigate possibilities of observing quark effects in nuclei by the analysis of bremsstrahlung in nuclear reactions. \textbf{Methods} Analyse the bremsstrahlung cross sections with established model in proton-nucleus scattering, by extending with inclusion of in-medium modified nucleon magnetic moments in nuclei by the QMC model. \textbf{Results} (1) After calibrating the model without the quark effects for experimental data (TAPS Collaboration data for $p + \isotope[197]{Au}$), we calculate the cross sections and observe the slight difference between the spectra for models with and without quark effects. Such result is found for the first time, confirming possibilities of observing the quark effects in the spectra of bremsstrahlung. (2) As found, quark effects are not enough to be observed in middle and heavy nuclei, as they have dominant incoherent contributions. (3) \isotope[18]{C} has minimal incoherent contribution concerning other carbon isotopes, where the quark effects should be minimal. In ratios between the spectra for \isotope[18]{C} and \isotope[12]{C} with and without the quark effects the difference is clearly observed. \textbf{Conclusions} We establish the new physical observable for the quark effects in nuclei in the bremsstrahlung accompanied in the nuclear reactions, which can be measured. The present suggestion is for the first time in both theoretically and experimentally to study the quark effects in nuclei via the bremsstrahlung.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

The paper proposes bremsstrahlung ratios between 18C and 12C as a new observable for QMC quark effects on nucleon magnetic moments, but the calculated difference is slight and the transfer from heavy-nucleus calibration looks shaky.

read the letter

The key point is that this paper suggests bremsstrahlung spectra ratios in proton scattering on 18C versus 12C could reveal in-medium quark effects through the QMC model's enhancement of nucleon magnetic moments. They take an existing bremsstrahlung model, calibrate it to TAPS data on p + 197Au without quark modifications, then insert the QMC-adjusted moments and recompute. The absolute spectra shift only slightly, but the authors claim the ratio makes the difference stand out because 18C has less incoherent contribution than other carbon isotopes. This is presented as the first such suggestion for studying quark effects this way. The work does a decent job of linking the established reaction formalism to QMC results and using real data for calibration. Focusing on light nuclei where the quark signal might not be swamped is a sensible choice given the model's sensitivity to magnetic moments. The soft spots are more substantial. The difference is described as slight in the spectra, yet no error bars, parameter variations, or statistical measures are given to show whether the ratio shift would actually be measurable. Calibrating on heavy gold and applying the same setup to light carbon isotopes risks missing differences in density, Fermi motion, and final-state interactions that do not cancel cleanly in the ratio. Other in-medium changes beyond magnetic moments are not varied, so the claimed signature could be mimicked by residual model issues. This is for nuclear theorists or experimentalists already working on medium modifications and low-energy reaction observables. A reader familiar with QMC or bremsstrahlung calculations might pick up the idea as a prompt for further checks. I would send it to peer review so the calculations and transfer assumptions can be examined in detail, though it needs added robustness tests to be convincing.

Referee Report

2 major / 1 minor

Summary. The manuscript proposes bremsstrahlung in proton-nucleus scattering as a probe for quark effects in nuclei. An established bremsstrahlung model is calibrated to TAPS data on p + 197Au without quark effects; in-medium nucleon magnetic-moment enhancements from the QMC model are then added. A slight difference appears in the absolute spectra, but the authors report that the difference becomes clearly visible in the 18C/12C spectral ratio, which they present as a new measurable observable for quark effects in nuclei.

Significance. If the result holds, the work would introduce a novel experimental signature for in-medium quark-structure modifications via a ratio of bremsstrahlung spectra. The sensitivity of incoherent bremsstrahlung to magnetic moments and the use of isotopic ratios to suppress common systematics are conceptually sound. The connection to a concrete QMC prediction adds falsifiability. Realization of this significance, however, requires demonstration that the reported difference survives quantitative uncertainty analysis and is not an artifact of the calibration procedure or unaccounted nuclear-mass dependence.

major comments (2)

[Abstract, Results (1)] Abstract, Results (1): the claim of a 'slight difference' between spectra with and without QMC magnetic-moment enhancement is presented without numerical values, uncertainty bands, or comparison to typical experimental resolution. This omission prevents assessment of whether the difference is detectable and undermines the assertion that the effect 'can be measured'.
[Abstract, Results (3)] Abstract, Results (3) and Conclusions: the central claim requires that the bremsstrahlung model, once fixed to p + 197Au data, remains sufficiently accurate for 12C and 18C that adding only the QMC-predicted magnetic-moment increase produces an unambiguous difference in the 18C/12C ratio. No justification is given for the transferability of the calibration across nuclei that differ substantially in mass, density, and Fermi motion; residual model deficiencies that vary between the two carbon isotopes could mimic or mask the reported ratio signature.

minor comments (1)

[Abstract, Results (2)] The abstract states that quark effects 'are not enough to be observed in middle and heavy nuclei' but provides no quantitative comparison of incoherent versus coherent contributions or of the relative size of the QMC correction across mass ranges.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the detailed review and valuable suggestions. We address the major comments point by point below, indicating where revisions will be made to the manuscript.

read point-by-point responses

Referee: [Abstract, Results (1)] Abstract, Results (1): the claim of a 'slight difference' between spectra with and without QMC magnetic-moment enhancement is presented without numerical values, uncertainty bands, or comparison to typical experimental resolution. This omission prevents assessment of whether the difference is detectable and undermines the assertion that the effect 'can be measured'.

Authors: We concur that the presentation of the 'slight difference' would benefit from quantitative details. In the revised manuscript, we will provide specific numerical values for the relative difference in the bremsstrahlung spectra, include uncertainty bands derived from variations in the model parameters, and compare the effect size to the experimental resolution of the TAPS detector to support the measurability claim. revision: yes
Referee: [Abstract, Results (3)] Abstract, Results (3) and Conclusions: the central claim requires that the bremsstrahlung model, once fixed to p + 197Au data, remains sufficiently accurate for 12C and 18C that adding only the QMC-predicted magnetic-moment increase produces an unambiguous difference in the 18C/12C ratio. No justification is given for the transferability of the calibration across nuclei that differ substantially in mass, density, and Fermi motion; residual model deficiencies that vary between the two carbon isotopes could mimic or mask the reported ratio signature.

Authors: The model used is an established one previously validated for various nuclei, and the parameters calibrated on the heavy 197Au system are expected to apply to lighter nuclei as they relate to fundamental interaction strengths rather than nucleus-specific features. The ratio of 18C to 12C is chosen precisely to minimize differences in nuclear structure effects. Nevertheless, we recognize the need for explicit justification. We will add a discussion in the revised manuscript explaining the model's transferability, referencing its prior applications to light nuclei and arguing that any residual deficiencies are largely common to both carbon isotopes and thus cancel in the ratio. revision: yes

Circularity Check

0 steps flagged

No significant circularity; calibration uses external data and QMC input is independent

full rationale

The derivation calibrates the bremsstrahlung model to external TAPS p+197Au data without quark effects, then adds independent QMC-predicted magnetic-moment enhancements to compute spectral differences and ratios for 12C/18C. This does not reduce any claimed prediction or observable to the inputs by construction, nor does it rely on self-citation chains or ansatze smuggled from prior author work. The central result (detectable ratio difference) is obtained by explicit calculation after external calibration and remains falsifiable against new measurements on the carbon isotopes. No load-bearing step equates the output to a fitted parameter or self-defined quantity.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 0 invented entities

The central claim rests on the QMC model supplying the correct in-medium magnetic-moment enhancement and on the bremsstrahlung formalism remaining valid after calibration to one data set; no new entities are postulated.

free parameters (1)

calibration parameters for bremsstrahlung model
Used to match TAPS Collaboration data for p + 197Au without quark effects before adding the QMC modification.

axioms (1)

domain assumption Incoherent bremsstrahlung dominates coherent emission and is very sensitive to nucleon magnetic moments in nuclei.
Stated in the Background section of the abstract as the basis for sensitivity to quark effects.

pith-pipeline@v0.9.0 · 6088 in / 1529 out tokens · 56133 ms · 2026-05-21T23:58:45.576109+00:00 · methodology

discussion (0)

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

IndisputableMonolith/Cost/FunctionalEquation.lean washburn_uniqueness_aczel unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

After calibrating the model without the quark effects for the experimental data (TAPS Collaboration data for p + 197Au), we calculate the cross sections and observe the slight difference between the spectra for models with and without quark effects.
IndisputableMonolith/Foundation/RealityFromDistinction.lean reality_from_one_distinction unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

the incoherent bremsstrahlung is very sensitive to the magnetic moments of nucleons in nuclei... QMC model, the nucleon magnetic moments in nuclei are enhanced

What do these tags mean?

matches: The paper's claim is directly supported by a theorem in the formal canon.
supports: The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends: The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses: The paper appears to rely on the theorem as machinery.
contradicts: The paper's claim conflicts with a theorem or certificate in the canon.
unclear: Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Forward citations

Cited by 1 Pith paper

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Reference graph

Works this paper leans on

16 extracted references · 16 canonical work pages · cited by 1 Pith paper

[1]

S. P. Maydanyuk, Enhancement of incoherent bremsstrahlung in proton-nucle us scattering in the ∆-resonance energy region, Phys. Rev. C 107 , 024618 (2023)

work page 2023
[2]

S. P. Maydanyuk and P.-M. Zhang, New approach to determine proton-nucleus interactions fro m experimental bremsstrahlung data, Phys. Rev. C 91 , 024605 (2015)

work page 2015
[3]

M. J. van Goethem, L. Aphecetche, J. C. S. Bacelar, H. Dela grange, J. Diaz, D. d’Enterria, M. Hoefman, R. Holzmann, H. Huisman, N. Kalantar-Nayestanaki, A. Kugler, H. L¨ ohner, G. Martinez, J. G. Messchendorp, R. W. Ostendorf, S. Schad- mand, R. H. Siemssen, R. S. Simon, Y. Schutz, R. Turrisi, M. Vo lkerts, V. Wagner, and H. W. Wilschut, Suppresion of so...

work page 2002
[4]

Clayton, W

J. Clayton, W. Benenson, M. Cronqvist, R. Fox, D. Krofche ck, R. Pfaﬀ, M. F. Mohar, C. Bloch, D. E. Fields, High energy gamma ray production in proton-induced reactions at 104, 14 5, and 195 MeV , Phys. Rev. C 45 , 1815 (1992)

work page 1992
[5]

J. E. Clayton, High energy gamma ray production in proton induced reaction s at energies of 104, 145, and 195 MeV , PhD thesis (Michigan State University, 1991)

work page 1991
[6]

X. Liu, S. P. Maydanyuk, P.-M. Zhang, and L. Liu, First investigation of hypernuclei in reactions via analys is of emitted bremsstrahlung photons, Phys. Rev. C 99 , 064614 (2019)

work page 2019
[7]

P. A. M. Guichon, A Possible Quark Mechanism for the Saturation of Nuclear Mat ter, Phys. Lett. B 200, 235 (1988)

work page 1988
[8]

Saito, K

K. Saito, K. Tsushima and A. W. Thomas, Nucleon and hadron structure changes in the nuclear medium a nd impact on observables, Prog. Part. Nucl. Phys. 58, 1 (2007)

work page 2007
[9]

Krein, A

G. Krein, A. W. Thomas and K. Tsushima, Nuclear-bound quarkonia and heavy-ﬂavor hadrons , Prog. Part. Nucl. Phys. 100, 161 (2018)

work page 2018
[10]

P. A. M. Guichon, J. R. Stone and A. W. Thomas, Quark-Meson-Coupling (QMC) model for ﬁnite nuclei, nuclea r matter and beyond , Prog. Part. Nucl. Phys. 100, 262 (2018)

work page 2018
[11]

D. H. Lu, A. W. Thomas, K. Tsushima, A. G. Williams and K. S aito, In-medium electron-nucleon scattering, Phys. Lett. B 417, 217 (1998)

work page 1998
[12]

D. H. Lu, K. Tsushima, A. W. Thomas, A. G. Williams and K. S aito, Electromagnetic form-factors of the bound nucleon , Phys. Rev. C 60 , 068201 (1999)

work page 1999
[13]

See Supplemental Material for this paper for details of calculations of the operator of emission and matrix element of emission of photons

work page
[15]

S. P. Maydanyuk, P.-M. Zhang, and L.-P. Zou, New approach for obtaining information on the many-nucleon structure in α decay from accompanying bremsstrahlung emission , Phys. Rev. C 93 , 014617 (2016)

work page 2016
[16]

S. P. Maydanyuk, Model for bremsstrahlung emission accompanying interacti ons between protons and nuclei from low energies up to intermediate energies: Role of magnetic emis sion, Phys. Rev. C 86 , 014618 (2012)

work page 2012
[17]

Tsushima, Magnetic moments of the octet, decuplet, low-lying charm, a nd low-lying bottom baryons in a nuclear medium , PTEP 043D02 (2022)

K. Tsushima, Magnetic moments of the octet, decuplet, low-lying charm, a nd low-lying bottom baryons in a nuclear medium , PTEP 043D02 (2022). 1 Manifestation of quark eﬀects in nuclei via bremsstrahlung analysis in the proton-nucleus scattering Supplemental Material I. MODEL A. Hamiltonian of proton-nucleus scattering and bremsstra hlung photon emission ...

work page doi:10.1103/physrevc.107.024618 2022

[1] [1]

S. P. Maydanyuk, Enhancement of incoherent bremsstrahlung in proton-nucle us scattering in the ∆-resonance energy region, Phys. Rev. C 107 , 024618 (2023)

work page 2023

[2] [2]

S. P. Maydanyuk and P.-M. Zhang, New approach to determine proton-nucleus interactions fro m experimental bremsstrahlung data, Phys. Rev. C 91 , 024605 (2015)

work page 2015

[3] [3]

M. J. van Goethem, L. Aphecetche, J. C. S. Bacelar, H. Dela grange, J. Diaz, D. d’Enterria, M. Hoefman, R. Holzmann, H. Huisman, N. Kalantar-Nayestanaki, A. Kugler, H. L¨ ohner, G. Martinez, J. G. Messchendorp, R. W. Ostendorf, S. Schad- mand, R. H. Siemssen, R. S. Simon, Y. Schutz, R. Turrisi, M. Vo lkerts, V. Wagner, and H. W. Wilschut, Suppresion of so...

work page 2002

[4] [4]

Clayton, W

J. Clayton, W. Benenson, M. Cronqvist, R. Fox, D. Krofche ck, R. Pfaﬀ, M. F. Mohar, C. Bloch, D. E. Fields, High energy gamma ray production in proton-induced reactions at 104, 14 5, and 195 MeV , Phys. Rev. C 45 , 1815 (1992)

work page 1992

[5] [5]

J. E. Clayton, High energy gamma ray production in proton induced reaction s at energies of 104, 145, and 195 MeV , PhD thesis (Michigan State University, 1991)

work page 1991

[6] [6]

X. Liu, S. P. Maydanyuk, P.-M. Zhang, and L. Liu, First investigation of hypernuclei in reactions via analys is of emitted bremsstrahlung photons, Phys. Rev. C 99 , 064614 (2019)

work page 2019

[7] [7]

P. A. M. Guichon, A Possible Quark Mechanism for the Saturation of Nuclear Mat ter, Phys. Lett. B 200, 235 (1988)

work page 1988

[8] [8]

Saito, K

K. Saito, K. Tsushima and A. W. Thomas, Nucleon and hadron structure changes in the nuclear medium a nd impact on observables, Prog. Part. Nucl. Phys. 58, 1 (2007)

work page 2007

[9] [9]

Krein, A

G. Krein, A. W. Thomas and K. Tsushima, Nuclear-bound quarkonia and heavy-ﬂavor hadrons , Prog. Part. Nucl. Phys. 100, 161 (2018)

work page 2018

[10] [10]

P. A. M. Guichon, J. R. Stone and A. W. Thomas, Quark-Meson-Coupling (QMC) model for ﬁnite nuclei, nuclea r matter and beyond , Prog. Part. Nucl. Phys. 100, 262 (2018)

work page 2018

[11] [11]

D. H. Lu, A. W. Thomas, K. Tsushima, A. G. Williams and K. S aito, In-medium electron-nucleon scattering, Phys. Lett. B 417, 217 (1998)

work page 1998

[12] [12]

D. H. Lu, K. Tsushima, A. W. Thomas, A. G. Williams and K. S aito, Electromagnetic form-factors of the bound nucleon , Phys. Rev. C 60 , 068201 (1999)

work page 1999

[13] [13]

See Supplemental Material for this paper for details of calculations of the operator of emission and matrix element of emission of photons

work page

[14] [15]

S. P. Maydanyuk, P.-M. Zhang, and L.-P. Zou, New approach for obtaining information on the many-nucleon structure in α decay from accompanying bremsstrahlung emission , Phys. Rev. C 93 , 014617 (2016)

work page 2016

[15] [16]

S. P. Maydanyuk, Model for bremsstrahlung emission accompanying interacti ons between protons and nuclei from low energies up to intermediate energies: Role of magnetic emis sion, Phys. Rev. C 86 , 014618 (2012)

work page 2012

[16] [17]

Tsushima, Magnetic moments of the octet, decuplet, low-lying charm, a nd low-lying bottom baryons in a nuclear medium , PTEP 043D02 (2022)

K. Tsushima, Magnetic moments of the octet, decuplet, low-lying charm, a nd low-lying bottom baryons in a nuclear medium , PTEP 043D02 (2022). 1 Manifestation of quark eﬀects in nuclei via bremsstrahlung analysis in the proton-nucleus scattering Supplemental Material I. MODEL A. Hamiltonian of proton-nucleus scattering and bremsstra hlung photon emission ...

work page doi:10.1103/physrevc.107.024618 2022