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 Ralf Seidl
      To study the strong interaction in nucleon structure and fragmentation


Understanding the strong interaction QCD:

We know, that the strong interaction, Quantum Chromo Dynamics (QCD) is responsible for almost all the visible mass in the universe. While the Higgs field gives quarks its mass the bulk of the mass of protons and neutrons originates from the QCD dynamics.
While it is possible to use QCD quantitatively when the energy scales are very large QCD bound states like the proton as well as their formation cannot be described quantitatively and need to be extracted from experiment
I am working on extracting these distribution and fragmentation functions especially under the inclusion of spin and transverse momentum

BNL photo link


Current Highlights:

- Transverse momentum dependent production cross sections of charged pions, kaons and protons in e+e- annihilation at 10.58 GeV

(RIKEN press release, Japanese) and Phys.Ref D 99, 112006

- the nonzero gluon spin contribution in PHENIX via neutral pions at 510 GeV

(DOE Nuclear Physics highlights) and (BNL Newsroom article)and (RIKEN, Japanese)

- Single spin Asymmetries in forward W production at PHENIX

Phys.Rev.D 98, 032007

BNL photo link


Ongoing Research activities:

  • gluon helicities at PHENIX
  • sea quark helicities at PHENIX
  • transverse spin asymmetries PHENIX
  • spin averaged fragmenation functions at Belle
  • spin dependent fragmenation functions at Belle
  • transverse momentum dependent fragmenation functions at Belle
  • forward RHIC spin upgrades
  • polarized electron ion collider EIC


    Selected recent presentations

  • DIS2016 (Hamburg, Germany, April 2016):"Spin Physics", invited plenary presentation (link)
  • DIS2016 (Hamburg, Germany, April 2016):"Gluon spin measurements in PHENIX", spin parallel session presentation (link)
  • SPIN2016 (Urbana,IL, USA, September 2016):"The Belle fragmentation program", invited presentation (link)
  • Nuclear physics long range plan QCD town meeting, (Philadelphia, PA, USA, September 2014):"Experimental overview: Nucleon spin structure", invited presentation(link)
  • Joint Meeting of the JPS and DNP, (Waikoloa, HI, USA, October 2014):"Three-dimensional imaging and spin: From Valence quarks to the sea", invited presentation in "Future Directions in high energy QCD"(link)
  • Hadron 2013, (Nara, Japan, November 2013):"Fragmentation function measurements", invited plenary presentation(link)

  • Older Research results:

  • Discovery of Sivers and Collins effects in HERMES PRL 94 (2005) (762 citations) and PhD Thesis

  • Measurement of Collins fragmenation in Belle PRL 96 (2006) (305 citations) and PRD 78 (2008)(260 citations)

  • see list of publications for other results

    backup content

  • BNL photo link BNL photo link BNL photo link

    More on Fragmentation

    More on Nucleon spin

    Last modified: Wed Jan 4 13:34:09 JST 2023