Narrow Results

String structures in degree 4 are associated with cancelation of anomalies of string theory in 10 dimensions. Fivebrane structures in degree 8 have recently been shown to be associated with cancelation of anomalies associated to fivebranes in string theory and M-theory. We introduce and describe Ninebrane structures in degree 12 and demonstrate how they capture some anomaly cancelation phenomena in M-theory. Along the way we also define certain variants, considered as intermediate cases in degrees 9 and 10, which we call 2-Orientation and 2-Spin structures, respectively. As in the lower degree cases, we also discuss the natural twists of these structures and characterize the corresponding topological groups associated to each of the structures, which likewise admit refinements to differential cohomology.

An extension of the general coordinate transformations algebra is constructed by means geometrical consistency conditions. A class of infinite invariants is derived. In particular we construct the consistent extension of the gravitational anomaly for each even dimension. The new contributions for these anomalies allow to define an improved Ward operator for which the symmetry is restored.

Evolutionary and cognitive examples are used to motivate an approach to the brittleness problem and automated flexible cognition, centering on the notion of an anomaly as the key focus of processing. Ongoing investigations based on this approach are discussed, including hypotheses regarding its promise for robust versatile machines.

In recent years, commodity markets have become increasingly popular among financial investors. While previous studies document a factor structure, not much is known about how prominent anomalies are priced in commodity futures markets. We examine a large set of such anomaly variables. We identify sizable premia for jump risk, momentum, skewness, and volatility-of-volatility. Other prominent variables, such as downside beta, idiosyncratic volatility, and MAX, are not priced in commodity futures markets. Commodity investors should rebalance their portfolios regularly. Returns for annual holding periods are substantially weaker than for monthly rebalancing.

This paper predicts the two most common stock market exits — mergers and drops — using logit models based on firm-level variables and analyzes the returns of stocks that have high exit probabilities. Such analysis is important for investors given that frequent exits are partly responsible for the large US listing gap (Doidge et al., 2017). High merger probability stocks have positive 3-factor alphas and lower-than-average volatility. Firms with high drop probabilities have anomalously negative 3-, 4-, and 5-factor alphas between $-1.8$% and $-4$% per month. Results are robust to controlling for the effects of skewness, volatility, and turnover on returns.

Experimental era of rare B-decays started with the measurement of B → K^*γ by CLEO in 1993, followed by the measurement of the inclusive decay B → X_sγ in 1995, which serves as the standard candle in this field. The frontier has moved in the meanwhile to the experiments at the LHC, in particular, LHCb, with the decay B⁰ → μ⁺μ⁻ at about 1 part in 1010 being the smallest branching fraction measured so far. Experimental precision achieved in this area has put the standard model to unprecedented stringent tests and more are in the offing in the near future. I review some key measurements in radiative, semileptonic and leptonic rare B-decays, contrast them with their estimates in the SM, and focus on several mismatches reported recently. They are too numerous to be ignored, yet, standing alone, none of them is significant enough to warrant the breakdown of the SM. Rare B-decays find themselves at the crossroads, possibly pointing to new horizons, but quite likely requiring an improved theoretical description in the context of the SM. An independent precision experiment such as Belle II may help greatly in clearing some of the current experimental issues.

In this presentation we review our work on Abelian Maxwell-Chern-Simons theory in three-dimensional AdS black brane backgrounds, with both integer and non-integer Chern-Simons coupling. Such theories can be derived from several string theory constructions, and we found exact solutions in the low frequency, low momentum limit (ω, k ≪ T, the hydrodynamic limit). Our results are translated into correlation functions of vector operators in the dual strongly coupled 1 + 1-dimensional quantum field theory with a chiral anomaly at non-zero temperature T, via the holographic correspondence. The applicability of the hydrodynamic limit is discussed, together with the comparison between an exact field theoretic computation and the found holographic correlation functions in the conformal case.

Anomaly cancellation between different sectors of a theory may mediate new interactions between gauge bosons. Such interactions lead to observable effects both at precision laboratory experiments and at accelerators. Such experiments may reveal the presence of hidden sectors or hidden extra dimensions.

Two-dimensional toy models display, in a gentler setting, many salient aspects of Quantum Field Theory. Here I discuss a concrete two-dimensional case, the Thirring model, which illustrates several important concepts of this theory: the anomalous dimension of the fields; the exact solvability; the anomalies of the Ward-Takahashi identities. Besides, I give a glimpse of the decisive role that this model plays in the study of an apparently unrelated topic: correlation critical exponents of two dimensional lattice systems of Statistical Mechanics.