Journal club

We are organizing a seminar on string field theory (SFT) and related topics (worldsheet theory, string amplitudes, compactifications, homotopy algebras…) on Thursday every 2 weeks. Talks are typically 1.5 hours long, but they may be longer for topics when necessary.

Our goal is to offer reviews, mini-lectures and communications of recent results. In the latter case, the recommended format is a general introduction of 30 min for students and non-specialists, followed by 1 hour of talk + discussions intertwined. However, speakers are free to organize their time differently. Speakers can present one of their papers, work in progress or even other papers they want to discuss. We hope that this regular journal club will help foster discussions within the SFT community and related fields and seed new collaborations and applications.

Structure (reference timezone is CEST, see this website for conversion):

  • 15:00 – 16:30 (CEST) [9:00 (EST), 19:30 (IST), 23:00 (JST)] : talk

Please register on the mailing list for announcements and obtaining the Zoom link. If you don’t see emails, please check your spam folder and, if necessary, mark the email as non-spam.


  • Subhroneel Chakrabarti
  • Harold Erbin
  • Renann Lipinski Jusinskas

Talks will be announced on this page and through the mailing list. You can also consult the calendar or events pages or subscribe to the SFT Google Calendar (ics version). Talks are also listed on Everyone is invited to discuss on Zulip.

Videos of the recorded talks will be posted in the String field theory Youtube channel.

Past seminars:

You can contact us for suggesting speakers.


  • Thursday 26 October 2023 : Olaf Hohm (Humboldt U.)
    Title: Double Copy, Double Field Theory & Homotopy Algebras

    Abstract: The double copy denotes a technology to relate the scattering amplitudes of Yang-Mills theory to those of gravity. While enormously successful at the level of scattering amplitudes, until recently there was no first-principle understanding of how to derive such relations. Such an understanding would be needed in order to describe, for instance, a double copy of classical solutions. I present an approach based on homotopy algebras such as L-infinity algebras that allows one to provide such a first-principle derivation, at least to some finite order in perturbation theory. To this end I review how to formulate Yang-Mills theory as an L-infinity algebra, how to “strip off” color to obtain a different kind of homotopy algebra and, finally, how to combine two copies of these exotic algebras to obtain the L-infinity algebra of gravity in the form of double field theory.

  • Thursday 26 October 2023 : Minjae Cho (Princeton U.)
    Title: On the symplectic form of the open string field theory

    Abstract: We explore the construction of the symplectic form on the phase space of classical solutions in open string field theory. We demonstrate its practical application by computing the energy of open string rolling tachyon solutions, which agrees with Sen’s proposal based on boundary conformal field theory.