# Nordic String Meeting 2021

Just got back from the Nordic String meeting in Stockholm, Sweden. The event was held at NORDITA and I learned that it’s actually the 30th installment (🤯). The last one took place in 2012 or so. Luckily, Niels Obers and this year’s organizers have decided to revive it this year and continue this beautiful tradition.

Most excitingly for me, I got the chance to give a talk in front of the Scandinavian community. And more importantly, to get to know some of the people. (Yes, I did feel like an invader a bit.)
Just as in Leuven last week, I presented the supergravity paper that we had published some time earlier this year. My original aim had been to take that structure and condense it from a 50 min talk to 20 min one. However, I didn’t really have a good feeling about this idea for some time. Finally, in the train from Groningen to Schiphol I decided to shake it up and came up with a new plan and new slides. The new talk is centered around T-duality and the question of whether there is a sensible notion of T-duality along a lightlike direction. In other words, it is asking the question of whether there is a T dual of the DLCQ of string theory. Naively the answer is a resounding no since the Buscher rule for the Kaluza-Klein scalar $\tilde{P} = P^{-1}$ is blowing up in the limit where the isometry becomes null. Remarkably, however, there is a subtle regularization of this limit making the whole procedure well-defined. The regularization explicitly breaks spacetime isotropy–and hence Lorentzian symmetries. You might have already guessed where this is going: It turns out that DLCQ is T dual to Gomis-Ooguri string theory. As such, the latter can be seen as an alternative approach to define the discrete light cone quantization in the first place. In the rest of the talk I explained how supersymmetry fits into this picture and presented the new multiplet and an outlook.

If you are interested you can have a look at my slides below