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A new simple PDF parametrization: Improved description of the HERA data

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Abstract.

We introduce a new parametrization for the parton distribution functions (PDFs) designed to be flexible in the small-x region. We implement it in the xFitter open-source PDF fitting tool, and compare it to the default xFitter parametrization, widely used for many PDF studies, and notably for the HERAPDF determination. We find that we can describe the combined inclusive HERA I+II data using NNLO theory with a significantly higher quality than HERAPDF2.0: the \(\chi^{2}\) is reduced by more than 60 units, having used only four more parameters. Our result highlights a significant parametrization bias in the default xFitter parametrization at small x, which would lead to even more dramatic effects when used for higher-energy colliders, where the small-x region is more relevant. We also find that the inclusion of small-x resummation, that was shown in previous studies to lead to similar improvements in the fit quality, further reduces the \(\chi^{2}\) by approximately 30 extra units.

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References

  1. S. Dulat, T.-J. Hou, J. Gao, M. Guzzi, J. Huston, P. Nadolsky et al., Phys. Rev. D 93, 033006 (2016) arXiv:1506.07443

    Article  ADS  Google Scholar 

  2. L. Harland-Lang, A. Martin, P. Motylinski, R. Thorne, Parton distributions in the LHC era: MMHT 2014 PDFs, arXiv:1412.3989

  3. NNPDF Collaboration (R.D. Ball), Parton distributions from high-precision collider data, arXiv:1706.00428

  4. J. Butterworth et al., J. Phys. G 43, 023001 (2016) arXiv:1510.03865

    Article  ADS  Google Scholar 

  5. S. Alekhin, J. Blümlein, S. Moch, R. Placakyte, Phys. Rev. D 96, 014011 (2017) arXiv:1701.05838

    Article  ADS  Google Scholar 

  6. P. Jimenez-Delgado, E. Reya, Phys. Rev. D 89, 074049 (2014) arXiv:1403.1852

    Article  ADS  Google Scholar 

  7. A. Accardi, L.T. Brady, W. Melnitchouk, J.F. Owens, N. Sato, Phys. Rev. D 93, 114017 (2016) arXiv:1602.03154

    Article  ADS  Google Scholar 

  8. S. Alekhin et al., Eur. Phys. J. C 75, 304 (2015) arXiv:1410.4412

    Article  ADS  Google Scholar 

  9. xFitter Developers' Team Collaboration (V. Bertone et al.), PoS DIS2017, 203 (2018) arXiv:1709.01151

    Google Scholar 

  10. ZEUS, H1 Collaboration (H. Abramowicz et al.), Eur. Phys. J. C 75, 580 (2015) arXiv:1506.06042

    Article  Google Scholar 

  11. ATLAS Collaboration (M. Aaboud et al.), Eur. Phys. J. C 77, 367 (2017) arXiv:1612.03016

    Article  ADS  Google Scholar 

  12. ATLAS Collaboration (M. Aaboud et al.), JHEP 02, 117 (2017) arXiv:1612.03636

    ADS  Google Scholar 

  13. CMS Collaboration (A.M. Sirunyan et al.), Eur. Phys. J. C 77, 459 (2017) arXiv:1703.01630

    Article  Google Scholar 

  14. CMS Collaboration (A.M. Sirunyan et al.), Eur. Phys. J. C 77, 746 (2017) arXiv:1705.02628

    Article  Google Scholar 

  15. M. Ciafaloni, D. Colferai, G. Salam, A. Stasto, Phys. Rev. D 68, 114003 (2003) arXiv:hep-ph/0307188

    Article  ADS  Google Scholar 

  16. M. Ciafaloni, D. Colferai, G. Salam, A. Stasto, JHEP 08, 046 (2007) arXiv:0707.1453

    Article  ADS  Google Scholar 

  17. G. Altarelli, R.D. Ball, S. Forte, Nucl. Phys. B 742, 1 (2006) arXiv:hep-ph/0512237

    Article  ADS  Google Scholar 

  18. G. Altarelli, R.D. Ball, S. Forte, Nucl. Phys. B 799, 199 (2008) arXiv:0802.0032

    Article  ADS  Google Scholar 

  19. R.S. Thorne, Phys. Rev. D 64, 074005 (2001) arXiv:hep-ph/0103210

    Article  ADS  Google Scholar 

  20. C.D. White, R.S. Thorne, Phys. Rev. D 75, 034005 (2007) arXiv:hep-ph/0611204

    Article  ADS  Google Scholar 

  21. R.D. Ball, V. Bertone, M. Bonvini, S. Marzani, J. Rojo, L. Rottoli, Eur. Phys. J. C 78, 321 (2018) arXiv:1710.05935

    Article  ADS  Google Scholar 

  22. xFitter Developers' Team Collaboration (H. Abdolmaleki et al.), Eur. Phys. J. C 78, 621 (2018) arXiv:1802.00064

    Article  Google Scholar 

  23. J. Gao, M. Guzzi, J. Huston, H.-L. Lai, Z. Li et al., Phys. Rev. D 89, 033009 (2014) arXiv:1302.6246

    Article  ADS  Google Scholar 

  24. P.D.B. Collins, An Introduction to Regge Theory and High-Energy Physics, in Cambridge Monographs on Mathematical Physics (Cambridge University Press, Cambridge, UK, 2009) https://doi.org/10.1017/CBO9780511897603

  25. R. Thorne, Phys. Rev. D 86, 074017 (2012) arXiv:1201.6180

    Article  ADS  Google Scholar 

  26. R.S. Thorne, R.G. Roberts, Phys. Rev. D 57, 6871 (1998) arXiv:hep-ph/9709442

    Article  ADS  Google Scholar 

  27. R. Thorne, Phys. Rev. D 73, 054019 (2006) arXiv:hep-ph/0601245

    Article  ADS  Google Scholar 

  28. L.A. Harland-Lang, A.D. Martin, P. Motylinski, R.S. Thorne, Eur. Phys. J. C 76, 186 (2016) arXiv:1601.03413

    Article  ADS  Google Scholar 

  29. T.-J. Hou, S. Dulat, J. Gao, M. Guzzi, J. Huston, P. Nadolsky et al., Phys. Rev. D 95, 034003 (2017) arXiv:1609.07968

    Article  ADS  Google Scholar 

  30. NNPDF Collaboration (R.D. Ball et al.), JHEP 04, 040 (2015) arXiv:1410.8849

    Google Scholar 

  31. V. Bertone, S. Carrazza, J. Rojo, Comput. Phys. Commun. 185, 1647 (2014) arXiv:1310.1394

    Article  ADS  MathSciNet  Google Scholar 

  32. M. Bonvini, S. Marzani, T. Peraro, Eur. Phys. J. C 76, 597 (2016) arXiv:1607.02153

    Article  ADS  Google Scholar 

  33. M. Bonvini, S. Marzani, C. Muselli, JHEP 12, 117 (2017) arXiv:1708.07510

    Article  ADS  Google Scholar 

  34. M. Bonvini, S. Marzani, JHEP 06, 145 (2018) arXiv:1805.06460

    Article  ADS  Google Scholar 

  35. M. Bonvini, Eur. Phys. J. C 78, 834 (2018) arXiv:1805.08785

    Article  ADS  Google Scholar 

  36. S. Forte, E. Laenen, P. Nason, J. Rojo, Nucl. Phys. B 834, 116 (2010) arXiv:1001.2312

    Article  ADS  Google Scholar 

  37. M. Bonvini, A.S. Papanastasiou, F.J. Tackmann, Resummation and Matching of $b$-quark Mass Effects in $b\bar{b}H$ Production, arXiv:1508.03288

  38. R.D. Ball, M. Bonvini, L. Rottoli, JHEP 11, 122 (2015) arXiv:1510.02491

    Article  ADS  Google Scholar 

  39. M. Botje, Comput. Phys. Commun. 182, 490 (2011) arXiv:1005.1481

    Article  ADS  Google Scholar 

  40. M. Bonvini, S. Marzani, Phys. Rev. Lett. 120, 202003 (2018) arXiv:1802.07758

    Article  ADS  Google Scholar 

  41. V. Bertone, R. Gauld, J. Rojo, JHEP 01, 217 (2019) arXiv:1808.02034

    Article  ADS  Google Scholar 

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Authors and Affiliations

  1. INFN, Sezione di Roma 1, Piazzale Aldo Moro 5, 00185, Roma, Italy

    Marco Bonvini

  2. University of Rome Tor Vergata and INFN, Sezione di Roma 2, Via della Ricerca Scientifica 1, 00133, Roma, Italy

    Francesco Giuli

Authors
  1. Marco Bonvini
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  2. Francesco Giuli
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Correspondence to Marco Bonvini.

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Bonvini, M., Giuli, F. A new simple PDF parametrization: Improved description of the HERA data. Eur. Phys. J. Plus 134, 531 (2019). https://doi.org/10.1140/epjp/i2019-12872-x

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  • DOI: https://doi.org/10.1140/epjp/i2019-12872-x

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