Particle Physics

In this talk, I will discuss various aspects of UV-complete R-symmetric QFTs. In particular, I will focus on a small set of operators that are well-defined in many such theories, and I will argue that one can use these operators to get a (partial) non-perturbative handle on the deep IR physics, including, possibly, a handle on certain aspects of the emergent symmetries. Throughout, I will highlight applications to particle physics.

The full machinery of supergravity (SUGRA) is required to fully understand many supersymmetric models. For the purpose of understanding phenomenology at colliders and in cosmology, the main concern is to ascertain the effects of SUGRA on the vacuum structure and particle spectrum. Practical calculations often require cumbersome manipulations of component field terms involving the full gravity multiplet. In this talk I will present an alternative gauge fixing for conformal SUGRA which decouples these gravity complications from SUGRA computations. This yields a simplified tree-level action for the matter fields in SUGRA which can be expressed compactly in terms of superfields and a modified conformal compensator. As a concrete application I will finally show the example of the mass spectrum of goldstini arising from a general admixture of F-term, D-term, and almost no-scale supersymmetry breaking.

I will discuss how to construct a consistent effective field theory when the differing modes of the theory have the same invariant mass scale. I will sketch some phenomenological applications of the formalism relevant for the LHC.

After a short introduction to general gauge mediation, we use the operator product expansion (OPE) to explore the dynamics of the hidden sector of SUSY breaking, much like the OPE is used in e+e- scattering to hadrons in QCD. Along the way we derive consequences that the N=1 superconformal symmetry puts on three-point functions of two current superfields with an arbitrary superconformal primary operator. Using those constraints we construct a ``supermultiplet'' of OPEs. Finally, we give approximations to soft masses, which can be used even in strongly-coupled theories.  
References: arXiv:1107.1721, 1109.4940

I will present a class of models in which the dark matter particle carries flavor quantum numbers, and has renormalizable contact interactions with Standard Model fields. In particular, I will focus on models where the dark matter flavor is identified with lepton flavor in the Standard Model. The region of parameter space where the dark matter has the right abundance to be a thermal relic is accessible at current direct detection experiments. A full simulation of the signal and backgrounds, including detector effects, shows that in a significant part of parameter space these theories can be discovered above Standard Model backgrounds at the LHC. Further, flavor and charge correlations among the final state leptons might allow models of this type to be distinguished from theories where dark matter couples to leptons but does not carry flavor.

We present strategies of searching for supersymmetric non-standard decays of Standard Model (SM)-like Higgs bosons (h2) at the Large Hadron Collider (LHC), motivated by ''Dark Light Higgs'' (DLH) scenario. The DLH sccenario represents a limit of the nearly-Peccei-Quinn-symmetric Next-to-Minimal Supersymmetric Standard Model, where there naturally co-exist two light singlet-like particles: a scalar (h1), a pseudoscalar (a1), and a light singlino-like DM candidate (\chi_1), all with masses of order 10 GeV or below. In this scenario, the SM-like Higgs boson typically decays dominantly into a pair of neutralinos, allowing themselves to be as light as below 100 GeV. We systematically study the searches of both the SM-like and the light Higgs bosons at the LHC, using the supersymmetric non-standard decay chains: h2 -> \chi_1 \chi_2, \chi_2 -> \chi_1 (h1, a1) with the h1 or a1 further decayed into a pair of fermions (including diMuon, diTau and b bbar, etc).

The channeling of the ion recoiling after a collision with a WIMP produces a larger ionization/scintillation signal in direct dark matter detection experiments than otherwise expected. I will present estimates of the channeling fractions and their impact on data fits. I will also discuss the possibility of having a daily modulation of the signal due to channeling. Since this modulation depends on the recoil directions and thus on the orientation of the detector with respect to the galaxy, it would be a background free signature. Finally, I will discuss other novel signatures which depend on the direction of recoils and are relevant for directional detectors: a ring of maximum recoil rate around the average arrival direction of WIMPs, aberration features and directional annual modulation amplitudes, in particular the North and South Galactic hemisphere annual modulation.

We investigate the theoretical implications of scale without conformal invariance in quantum field theory. We argue that the RG flows of such theories correspond to recurrent behaviors, i.e. limit cycles or ergodicity. We discuss the implications for the a-theorem and show how dilatation generators do generate dilatations. Finally, we discuss possible well-behaved non-conformal scale-invariant examples.

I will discuss magnetic properties of superconductors, first in a model independent way and then by using holographic models. This approach has the advantage of highlighting the generic features of superconducting materials and, at the same time, the predictions of specific models. I will start with the Meissner effect and the vortices. Given the importance of the magnetic field dynamics in these phenomena, I will describe how to introduce a dynamical gauge field in holography. Then I will show that the holographic superconductor, like all known high-temperature superconductors, is Type II. Finally, I will discuss the case of hollow cylindrical superconductors threaded by an axial magnetic field. The physics of these systems is periodic with respect to the magnetic flux, with a period that depends on weather non-local quantum effects are suppressed or not. In the holographic model these effects are not suppressed when the radius of the cylinder is below the critical value at which the Hawking-Page phase transition takes place.

The Standard Model is currently the theory which describes the most fundamental constituents of matter and the forces which govern their interactions. Since the start-up of the LHC accelerator, the ATLAS detector has collected sufficient data to allow tests of this theory at the smallest distance scales ever probed. The objective is to find significant deviations between the observed data and the Standard Model predictions, revealing the existence of new phenomena. For example, some theories in which the universe has more than 4 space-time dimensions predict that LHC collisions could produce gravitons - the particles responsible for the gravitational interaction. Such events would feature a single jet of hadronic particles in the detector and a large amount of

We propose models of symmetric WIMP dark matter in which dark matter annihilations generate the baryon asymmetry. We call this mechanism "WIMPy baryogenesis". This provides a dynamical connection between the late-time abundances of both dark matter and baryons. We construct explicit models of leptogenesis and baryogenesis at the weak scale, and find the "miraculous" result that, for order one couplings and weak scale masses for any new fields, the baryon asymmetry and dark matter relic density from WIMPy baryogenesis match the observed values. We also discuss implications for the LHC and dark matter detection experiments.