Schedule: Spring Term 2025-26

The seminars are taking place on Zoom every second Tuesday at 11 am (all times in US Eastern Time Zone).

The Seminar Series on String Phenomenology is currently in session!

Jan 27th 2025: 

• 11:00: "Toward an Effective Theory of the Volume Modulus", Naman Agarwal, University of Manitoba

Abstract: We investigate the 4-dimensional effective theory of the warped volume modulus in the presence of stabilizing effects from gaugino condensation by analyzing the linearized 10-dimensional supergravity equations of motion. Warping is generally expected to scale down the masses of bulk modes to the IR scale at the tip of a throat. We find that the mass of the warped volume modulus evades expectations and is largely insensitive to the effects of warping, even in strongly warped backgrounds. Instead, the mass is parametrically tied to the 4-dimensional AdS curvature scale $m^2 \sim \mathcal{O}(1) \hat{R}_{AdS}$, presenting a challenge for scale separation in these backgrounds. We trace this effect to a universal contribution arising from the 10-dimensional equations of motion, and comment on the importance of a 10-dimensional treatment of the warped volume modulus for effective field theories and model building.

• 11:30: "The Gravitational Wave Landscape of Cosmic String Networks with Time-Dependent Tension",  Luca Brunelli, University of Bologna

Abstract: In this talk, I will present the phenomenology of cosmic string networks with a time-dependent tension within the framework of Type IIB string theory. The time dependence of the tension is inherited by the dynamics of the compactification moduli, which set all the physical scales of the 4d effective field theory.  Hence, the post-inflationary evolution of the moduli can be directly linked to the dynamics of the cosmic string network, capturing its history from formation to gravitational wave emission. In the first part of the talk, I will describe the mechanism by which a population of isolated loops of fundamental or effective strings can grow in comoving size and eventually percolate into a network, depending on the dynamics of the moduli. In the second part, I will show how the time variation of the tension of cosmic strings is constrained by dynamical bounds inspired by the Swampland program. As a consequence, also the spectral index of the gravitational wave spectrum emitted by a scaling network of cosmic strings with time-dependent tension is similarly bounded.