Talks

The ordinary atoms that make up the known universe, from our bodies and the air we breathe to the planets and stars, constitute only 5 percent of all matter and energy in the cosmos. The remaining 95 percent is a recipe of 25 percent dark matter and 70 percent dark energy, both nonluminous components whose nature remains a mystery.

In her March 2 public lecture, Katherine Freese will recount the hunt for dark matter, from the discoveries of visionary scientists like Fritz Zwicky, the Swiss astronomer who coined the term "dark matter" in 1933, to the deluge of data today from underground laboratories, satellites in space, and the Large Hadron Collider.

We study two-dimensional (4, 4) superconformal field theories of central charge c = 6, corresponding to nonlinear sigma models on K3 surfaces, using the superconformal bootstrap method. This is made possible through a surprising relation between the BPS N = 4 superconformal blocks of c = 6 and bosonic Virasoro conformal blocks of c = 28, and an exact result on the moduli dependence of a certain integrated BPS 4-point function. Nontrivial bounds on the non-BPS spectrum are obtained in the K3 CFT as functions of the CFT moduli, that interpolate between the free orbifold points and singular CFT points. We observe directly from the CFT perspective the signature of a continuous spectrum above a gap at the singular moduli, and find numerically an upper bound on this gap that is saturated by the A1 N = 4 cigar CFT.