Curiosities: Sudakov Safety

  • Simone Marzani
  • Gregory Soyez
  • Michael Spannowsky
Part of the Lecture Notes in Physics book series (LNP, volume 958)


In this Chapter we go back to the SoftDrop algorithm and we study two variables deeply connected to it: the angular separation of the two subjets that pass SoftDrop and their momentum sharing. We find that while the former can be described using the all-order techniques described so far, the latter one cannot be. It instead exhibits peculiar features. This observable is not collinear safe for all values of the angular exponent β but it belongs to the wider class of Sudakov-safe observables.


  1. 14.
    STAR collaboration, K. Kauder, Measurement of the shared momentum fraction z g using jet reconstruction in p+p and Au+Au collisions with STAR. Nucl. Phys. A967, 516–519 (2017). [1704.03046]Google Scholar
  2. 49.
    A.J. Larkoski, J. Thaler, Unsafe but calculable: ratios of angularities in perturbative QCD. J. High Energy Phys. 1309, 137 (2013) . [1307.1699]Google Scholar
  3. 50.
    A.J. Larkoski, S. Marzani, G. Soyez, J. Thaler, Soft drop. J. High Energy Phys. 1405, 146 (2014). [1402.2657]Google Scholar
  4. 51.
    A.J. Larkoski, S. Marzani, J. Thaler, Sudakov safety in perturbative QCD. Phys. Rev. D91, 111501 (2015) . [1502.01719]Google Scholar
  5. 64.
    M. Cacciari, G.P. Salam, G. Soyez, The catchment area of jets. J. High Energy Phys. 04, 005 (2008) . [0802.1188]ADSCrossRefGoogle Scholar
  6. 65.
    F.A. Dreyer, G.P. Salam, G. Soyez, The Lund jet plane. J. High Energy Phys. 12, 064 (2018). [1807.04758]Google Scholar
  7. 177.
    S. Marzani, L. Schunk, G. Soyez, A study of jet mass distributions with grooming. J. High Energy Phys. 07, 132 (2017). [1704.02210]Google Scholar
  8. 191.
    S. Sapeta, Q.C. Zhang, The mass area of jets. J. High Energy Phys. 06, 038 (2011). [1009.1143]Google Scholar
  9. 192.
    A. Larkoski, S. Marzani, J. Thaler, A. Tripathee, W. Xue, Exposing the QCD splitting function with CMS open data. Phys. Rev. Lett. 119, 132003 (2017). [1704.05066]Google Scholar
  10. 193.
    CMS collaboration, Y. Chen, Jet substructure through splitting functions and mass in pp and PbPb collisions at 5.02 TeV with CMS. Nucl. Phys. A967, 512–515 (2017)Google Scholar
  11. 194.
    ALICE collaboration, D. Caffarri, Exploring jet substructure with jet shapes in ALICE. Nucl. Phys. A967, 528–531 (2017). [1704.05230]Google Scholar
  12. 195.
    K. Lapidus, M.H. Oliver, Hard substructure of quenched jets: a Monte Carlo study. 1711.00897Google Scholar
  13. 203.
    R. Kunnawalkam Elayavalli, K.C. Zapp, Medium response in JEWEL and its impact on jet shape observables in heavy ion collisions. J. High Energy Phys. 07, 141 (2017). [1707.01539]Google Scholar
  14. 204.
    D. Neill, Non-global and clustering effects for groomed multi-prong jet shapes. 1808.04897Google Scholar
  15. 205.
    A. Tripathee, W. Xue, A. Larkoski, S. Marzani, J. Thaler, Jet substructure studies with CMS open data. Phys. Rev. D96, 074003 (2017). [1704.05842]Google Scholar
  16. 206.
    J. Gallicchio, M.D. Schwartz, Seeing in color: jet superstructure. Phys. Rev. Lett. 105, 022001 (2010). [1001.5027]Google Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Simone Marzani
    • 1
  • Gregory Soyez
    • 2
  • Michael Spannowsky
    • 3
  1. 1.Dipartimento di FisicaUniversità di GenovaGenovaItaly
  2. 2.Institut de Physique TheoriqueCNRS UMR 3681, CEA SaclayGif-sur-Yvette cedexFrance
  3. 3.Department of Physics, Institute for Particle Physics PhenomenologyDurham UniversityDurhamUK

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