High Energy Physics

Since the Higgs, the LHC has offered no discoveries despite a sweeping hunt for new resonances. However, many well-motivated new physics models would not turn up in resonance searches, but could instead be uncovered in existing and forthcoming LHC data, by searching for novel angular distributions of Standard Model particles. I will show that in the upcoming years at the LHC, (1) through radiative corrections, dark matter can turn up in dilepton scattering angles in the parametric regions where it would elude conventional missing energy-based searches; the scattering patterns can reveal dark matter's mass, self-conjugation property, spin, and chirality of interactions, (2) through tree level interference, leptoquarks may emerge in dilepton scattering angles long before they would in dedicated direct searches; these angular measurements would also overtake the excellent sensitivities of low-energy precision measurements of atomic parity violation, and (3) Higgs Yukawa couplings to light quarks of the size of the bottom Yukawa could be measured using the Higgstrahlung scattering angle.

The talk will review the computation of the three point function of gauge-invariant operators in the planar N=4 SYM theory using integrability-based methods. The structure constant can be decomposed, as proposed by Basso, Komatsu and Vieira, in terms of two form-factor-like objects (hexagons). The multiple sums and integrals implied by the hexagon decomposition can be performed in the large-charge limit, and be compared to the results obtained by semiclassics. I will discuss a method to perform these sums and the contributions currently accessible by this approach.

I will introduce the spectral function method in the context of conformal bootstrap. I will discuss some applications of this method in two dimensions: (1) substantial evidence for the conjecture that the only unitary c>1 CFT with Virasoro primaries of bounded spin is Liouville theory, (2) detailed modular constraints on the spectrum of small c CFTs, (3) spectral density of large c CFTs with large gap, in connection to the (non-)universality of BTZ black hole entropy.

Sub-GeV dark matter is a theoretically motivated but largely unexplored paradigm of dark matter. In this talk, I will discuss recent work on the direct detection of sub-GeV dark matter through dark matter-electron scattering. I will present some motivated models that can be probed with these techniques as well as projections for current and near-term noble liquid, semiconductor, and scintillator experiments. Finally, I will discuss some new techniques that may allow us to more robustly discriminate between dark matter signatures and background.

I will discuss the chiral algebra W_infty which is obtained from the Virasoro algebra by adding fields of spin 3, 4, .... Via a non-local non-linear map one can show that it is equivalent to Tsymbaliuk's Yangian of affine u(1). In this way we find an infinite number of commuting conserved charges. Diagonalizing these, the representation theory reduces to combinatorial study of plane partitions, 3-dimensional generalization of the Young diagrams. Tsymbaliuk's presentation can be derived from RTT relations using Maulik-Okounkov's free boson R-matrix.

Recently a boundary energy-momentum tensor Tzz has been constructed from the soft graviton operator for any 4D quantum theory of gravity in asymptotically flat space. Up to an "anomaly" which is one-loop exact, Tzz generates a Virasoro action on the 2D celestial sphere at null infinity. Here we show by explicit construction that the effects of the IR divergent part of the anomaly can be eliminated by a one-loop renormalization that shifts Tzz.

Utilizing the Fermi measurement of the gamma-ray spectrum toward the Galactic Center, we derive some of the strongest constraints to date on the dark matter (DM) lifetime in the mass range from hundreds of MeV to above an EeV. Our profile-likelihood based analysis relies on 413 weeks of Fermi Pass 8 data from 200 MeV to 2 TeV, along with up-to-date models for diffuse gamma-ray emission within the Milky Way. We model Galactic and extragalactic DM decay and include contributions to the DM-induced gamma-ray flux resulting from both primary emission and inverse-Compton scattering of primary electrons and positrons. For the extragalactic flux, we also calculate the spectrum associated with cascades of high-energy gamma-rays scattering off of the cosmic background radiation. We argue that a decaying DM interpretation for the 10 TeV-1 PeV neutrino flux observed by IceCube is disfavored by our constraints. We interpret the results in terms of individual final states and in the context of simplified scenarios such as a hidden-sector glueball model.

The subject of quantum field theory in mixed states of quantum matter is an old and rich one. The natural setting to discuss field theory in a mixed state is the Schwinger-Keldysh formalism. The subject of this talk is the set of peculiar symmetries that arise in Schwinger-Keldysh theories, and how they may be accounted for in effective field theory. In particular, when the mixed state is thermal, the effective description is constrained by two BRST-like supercharges which, at low energies, generate an algebra akin to minimal supersymmetric quantum mechanics. If time allows, I will also discuss a sort of Schwinger-Keldysh bootstrap for effective actions on more complicated closed-time-contours, which describe the out-of-time-ordered correlation functions that diagnose early-time chaotic growth in quantum systems.

The conformal bootstrap aims to calculate scaling dimensions and correlation functions in various theories, starting from general principles such as unitarity and crossing symmetry.  I will explain that local operators are not independent of each other but organize into analytic functions of spin, and I will present a formula which quantifies the consequences of this fact.  This will include a controlled approximation to the operator spectrum at large spin, as well as new bounds over the strength of bulk higher-derivative interactions in large-N theories with a sparse spectrum. These bounds, previously conjectured to exist using gauge-gravity duality, encode causality of the bulk theory.  Based on 1703.00278.

Just like how milli-electric charged particles can exist, so can milli-magnetic charged particles.  We review simple ways of evading the standard quantization arguments and why there are no model independent constraints on magnetically charged particles, milli-charged or not.  We then provide the first ever model independent bounds coming from magnetar cooling arguments.