Mar 20, 2018
Tuesday

11:00 AM  12:00 PM


Periods and quasiperiods of modular forms and Dbrane masses on the quintic
Albrecht Klemm (Hausdorff Research Institute for Mathematics, University of Bonn)

 Location
 MSRI: Simons Auditorium
 Video

 Abstract
We consider one complex structure parameter mirror families $W$ of CalabiYau 3folds with PicardFuchs equations of hypergeometric type. By mirror symmetry the even Dbrane masses of the orginal CalabiYau $M$ can be identified with four periods w.r.t. to an integral symplectic basis of $H_3(W,Z)$ at the point of maximal unipotent monodromy. It was discovered by Chad Schoen in 1986 that the singular fibre of the quintic at the conifold point gives rise to a Hecke eigen form of weight four $f_4$ on $\Gamma_0(25)$ whose Fourier coefficients $a_p$ are determined by counting solutions in that fibre over the finite field $\mathbb{F}_{p^k}$. The Dbrane masses at the conifold are given by the transition matrix $T_{mc}$ between the integral symplectic basis and a Frobenius basis at the conifold. We predict and verify to very high precision that the entries of $T_{mc}$ relevant for the D2 and D4 brane masses are given by the two periods (or Lvalues) of $f_4$. These values also determine the behaviour of the WeilPetersson metric and its curvature at the conifold. Moreover we describe a notion of quasi periods and find that the two quasi period of $f_4$ appear in $T_{mc}$. We extend the analysis to the other hypergeometric one parameter 3folds and comment on simpler applications to local CalabiYau 3folds and polarized K3 surfaces.
 Supplements



