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Measurability of pressure inside the proton

Nature volume 570, pages E1–E2 (2019)Cite this article

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The Original Article was published on 16 May 2018

ARISING FROM V. D. Burkert et al. Nature https://doi.org/10.1038/s41586-018-0060-z (2018)

Understanding the internal structure of the proton—that is, how it is built from its fundamental constituents, quarks and gluons—is one of the great challenges of modern high-energy physics. Recently, Burkert et al.1 determined the quark pressure distribution inside the proton from experimental data on deeply virtual Compton scattering (DVCS) obtained by the CLAS Collaboration, using the parameterization of DVCS structure functions proposed by Kumerički and Müller2 (KM). This study repeats this procedure using more flexible parameterization by neural networks to improve the analysis of the uncertainty. The obtained results demonstrate that the experimental data used by Burkert et al.1 are actually consistent with zero quark pressure in the proton.

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Fig. 1: Imaginary (left) and real (right) part of H\(\left({\boldsymbol{\xi }},{\boldsymbol{t}}){\boldsymbol{.}}\right)\)

Data availability

The experimental data used in this work are publicly available at http://clasweb.jlab.org/physicsdb. A Fourier transformed version of these data is available at https://github.com/openhep/dterm18.

Code availability

The code used for the analysis is available at https://github.com/openhep/dterm18. This code is to be used together with the neural network software package PyBrain13 and the software implementation of formulas for DVCS cross-sections by Belitsky et al.14.

References

  1. Burkert, V. D., Elouadrhiri, L. & Girod, F. X. The pressure distribution inside the proton. Nature 557, 396–399 (2018).

    Article  CAS  ADS  Google Scholar 

  2. Kumerički, K. & Müller, D. Deeply virtual Compton scattering at small x B and the access to the GPD H. Nucl. Phys. B 841, 1–58 (2010).

    Article  ADS  Google Scholar 

  3. Polyakov, M. V. Generalized parton distributions and strong forces inside nucleons and nuclei. Phys. Lett. B 555, 57–62 (2003).

    Article  CAS  ADS  MathSciNet  Google Scholar 

  4. Polyakov, M. V. & Weiss, C. Skewed and double distributions in pion and nucleon. Phys. Rev. D 60, 114017 (1999).

    Article  ADS  Google Scholar 

  5. Teryaev, O. V. Analytic properties of hard exclusive amplitudes. Preprint at http://arXiv.org/abs/hep-ph/0510031 (2005).

  6. Polyakov, M. V. & Son, H.-D. Nucleon gravitational form factors from instantons: forces between quark and gluon subsystems. J. High Energ. Phys. 2018, 156 (2018).

    Article  Google Scholar 

  7. Polyakov, M. V. & Schweitzer, P. Forces inside hadrons: pressure, surface tension, mechanical radius, and all that. Int. J. Mod. Phys. A 33, 1830025 (2018).

    Article  CAS  ADS  Google Scholar 

  8. Anikin, I. V. et al. Nucleon and nuclear structure through dilepton production. Acta Phys. Pol. B 49, 741–784 (2018).

    Article  ADS  MathSciNet  Google Scholar 

  9. Kumerički, K., Müller, D. & Schäfer, A. Neural network generated parametrizations of deeply virtual Compton form factors. J. High Energ. Phys. 2011, 073 (2011).

    Article  Google Scholar 

  10. Girod, F. X. et al. Measurement of deeply virtual Compton scattering beam-spin asymmetries. Phys. Rev. Lett. 100, 162002 (2008).

    Article  CAS  ADS  Google Scholar 

  11. Jo, H. et al. Cross sections for the exclusive photon electroproduction on the proton and generalized parton distributions. Phys. Rev. Lett. 115, 212003 (2015).

    Article  CAS  ADS  Google Scholar 

  12. Dupré, R., Guidal, M., Niccolai, S. & Vanderhaeghen, M. Analysis of deeply virtual Compton scattering data at Jefferson Lab and proton tomography. Eur. Phys. J. A 53, 171 (2017).

    Article  ADS  Google Scholar 

  13. Schaul, T. et al. PYBRAIN. J. Mach. Learn. Res. 11, 743–746 (2010).

    Google Scholar 

  14. Belitsky, A. V., Müller, D. & Ji, Y. Compton scattering: from deeply virtual to quasi-real. Nucl. Phys. B 878, 214–268 (2014).

    Article  CAS  ADS  MathSciNet  Google Scholar 

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Acknowledgements

I thank V. D. Burkert, F. X. Girod, D. Müller, M. Polyakov and P. Schweitzer for discussions. This work is supported by the Croatian Science Foundation under project number 8799 and by the QuantiXLie Center of Excellence through grant KK.01.1.1.01.0004.

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  1. Department of Physics, Faculty of Science, University of Zagreb, Zagreb, Croatia

    Krešimir Kumerički

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Correspondence to Krešimir Kumerički.

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Kumerički, K. Measurability of pressure inside the proton. Nature 570, E1–E2 (2019). https://doi.org/10.1038/s41586-019-1211-6

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