Particle Physics

I discuss a new scenario called Hylogenesis (hylo=matter) that explains the baryon and dark matter densities of Universe in a unified way. Early universe dynamics generate the baryon asymmetry and an equal antibaryon asymmetry in a GeV-scale hidden sector. The hidden antibaryons are dark matter. Our model has a striking signature that dark matter can annihilate baryons, mimicking nucleon decay. I discuss the effective nucleon decay rates and implications for existing nucleon decay searches.

Recent observations first made in string theory led to the realization that introducing various ``deformations" (finite volume, appropriate double-trace operators...) allows for an analytic study of many nonperturbative aspects of arbitrary four-dimensional gauge theories. Notably, the confinement mechanism, the generation of mass gap, and, in some cases, chiral symmetry breaking can be studied in a theoretically controlled manner. In this talk, I will review: i.) the ideas and tools involved, ii.) the main results obtained so far in this approach (and its limitations), iii.) our understanding of its relation to other approaches to (non-)supersymmetric gauge dynamics, iv.) ongoing and possible future work.

The D0 Collaboration recently reported a 3.2sigma deviation from the standard model prediction in the like-sign dimuon asymmetry. I will discuss the implications of this anomaly assuming that new physics contributes only to B_{d,s} mixing. The data allow universal new physics with similar contributions relative to the SM in the B_d and B_s systems, but favors a larger deviation in B_s than in B_d mixing. The general minimal flavor violation framework with flavor diagonal CP violating phases can account for the former and remarkably even for the latter case. This observation makes it simpler to speculate about which extensions with general flavor structure may also fit the data.

Higher derivative extensions of the Standard Model are renormalizable but without a quadratic divergent higgs mass. Electroweak presision data constraint the scale of the higher derivatives to at least a few TeV, but then these models have no flavor problem. We skim through these and other interesting results, most remarkably causality as an emergent characteristic at long distances. But we start by explaining the indefinite metric quantization procedure proposed by Lee and Wick which is necessary for unitary.

The idea of an effective conformal theory describing the low-lying spectrum of the dilatation operator in a CFT is developed. Such an effective theory is useful when the spectrum contains a hierarchy in the dimension of operators, and a small parameter whose role is similar to that of 1/N in a large N gauge theory. These criteria insure that there is a regime where the dilatation operator is modified perturbatively. Global AdS is the natural framework for perturbations of the dilatation operator respecting conformal invariance, much as Minkowski space naturally describes Lorentz invariant perturbations of the Hamiltonian. Assuming that the lowest-dimension single-trace operator is a scalar, O, I consider the anomalous dimensions, gamma(n,l), of the double-trace operators of the form O (del^2)^n (del)^l O. Purely from the CFT, perturbative unitarity places a bound on these dimensions; non-renormalizable AdS interactions lead to violations of the bound at large values of n. I also consider the case that these interactions are generated by integrating out a heavy scalar field in AdS. The presence of the heavy field "unitarizes" the growth in the anomalous dimensions, and leads to a resonance-like behavior in gamma(n,l) when n is close to the dimension of the CFT operator dual to the heavy field. Finally, I demonstrate that bulk flat-space S-matrix elements can be extracted from the large n behavior of the anomalous dimensions. This leads to a direct connection between the spectrum of anomalous dimensions in d-dimensional CFTs and flat-space S-matrix elements in d+1 dimensions

CRESST is a cryogenic dark matter search located at the Laboratori Nazionali del Gran Sasso in Italy. Scintillating CaWO4 crystals are operated as cryogenic calorimeters. The phonon (heat) signal measured with a tungten transition edge sensor on the surface of these crystals allows a precise determination of the energy deposited in the crystal, independent of the type of interaction. A light signal, simultaneously registered by a separate cryogenic detector, serves to identify the type of interaction. This phonon/light technique allows a discrimination of electron recoils induced by radioative backgrounds from the searched nuclear recoils with high efficiency ,and, to some extent, even to determine which type of nucleus was recoiling. I will present results from 564 kg-days of data of the presently still ongoing run, which reveal an unexpected excess of oxygen recoils. To shine some light on the nature of these events, I will discuss possible backgrounds in some detail.

The consequences of the fact that electroweak scale particles are often produced beyond threshold has been appreciated only recently. Decay products of boosted objects tend to be collimated and their final state radiation (FSR) might overlap. It has been shown that it can be advantageous to collect all FSR of a decaying resonance in a so-called 'fat jet' and apply subjet techniques to it to obtain a good mass reconstruction of the resonance and an improved background rejection. In my talk I would like to cover recent developments in this field and discuss applications to Higgs searches and top reconstruction within and beyond the Standard Model.

We formulate a numerical procedure to calculate Hawking radiation during non-equilibrium black hole formation. The procedure is applied to a static string in thermal AdS and it is shown that for an arbitrary initial state, the final state is an equilibrated heavy quark string. The fluctuations in the quark string are transmitted from the horizon to the boundary leading to Brownian motion in the boundary theory.

I will discuss the collider signatures of heavy, long-lived, neutral particles that decay to charged particles plus missing energy. The focus will be the case of a neutralino NLSP decaying to Z and gravitino within the context of General Gauge Mediation (based on arXiv:1006.4575). I will show that the LHC has the potential for early discovery of such a long-lived particle if its lifetime (c tau) is between about 0.1 millimeters and 100 meters. I will also discuss the use of timing and pointing measurements to fully reconstruct kinematics in events with displaced decays.

Large mixing angles and a mild mass hierarchy are observed in neutrino oscillations, in stark contrast with the quarks and charged leptons sectors where very hierarchical masses come along with small mixings. We review and discuss the neutrino mass patterns that are technically natural, in the context of the seesaw mechanism and with a quark-lepton unification perspective. We show that a seesaw in six dimensions offers an elegant and unique solution to the flavor puzzle. An explicit model is constructed, with a vortex background on a sphere. It offers an explanation for the replication of families in the Standard Model, and predicts suppressed flavour violating interactions.