سازگاری کنش مؤثر نظریه ریسمان با T-دوگانی نیازمند شرایط مرزی خاصی در مرزهای فضاست. این شرایط مرزی قیدهایی را بر بازتعریف میدان‌ها و اصلاحاتی را برای تبدیلات T-دوگانی ایجاب می‌کند. دکتر محمد رضا گروسی در این زمینه در گروه فیزیک انرژی-بالا در پژوهشکدهٔ فیزیک پژوهشگاه دانش‌های بنیادی (IPM) سخنرانی کرده است.
عنوان سخنرانی: بازتعریف میدان‌ها با مشتقات مرتبه بالاتر در حضور شرایط مرزی
سخنران: دکتر محمد رضا گروسی (دانشگاه فردوسی مشهد)
ویدیوی این سخنرانی در زیر در دسترس است.
Title: Higher-derivative field redefinitions in the presence of boundary
Speaker: Mohammad Reza Garousi
Affiliation: Ferdowsi University of Mashhad
Abstract:
Recently it has been proposed that the consistency with T-duality requires the effective action of string theory at order $\alpha’^n$ satisfies the least action principle provided that the values of the massless fields and their derivatives up to order $n$ are known on the boundary. In this lecture, I speculate that this boundary condition constrains the field redefinitions and the corrections to the T-duality transformations in the presence of the boundary, e.g. at order, $\alpha’$, the metric does not change and all other massless fields should change to include only the first derivative of the massless fields. Using these field redefinitions, we write all gauge-invariant bulk and boundary couplings in the bosonic string theory at order $\alpha’$ in a minimal scheme. Then using the assumption that the classical effective action of the string theory at the critical dimension is background independent, we fix the coefficients of the independent gauge-invariant couplings by imposing$O(1,1)$ symmetry when the background has a circle and by imposing $O(d,d)$ symmetry when the background has $T^d$. These constraints fix the bulk action up to an overall factor, and the boundary action up to three parameters. By requiring the gravity couplings in the boundary action to be consistent with those in the Chern-Simons gravity, the three boundary parameters are also fixed. Up to the above restricted field redefinitions, the bulk and boundary couplings are exactly those in the K.A. Meissner action and its corresponding boundary action.
Date: Tuesday, December 21st – ۳۰ آذرماه
2:00 p.m (Tehran time)
