MASS 2014 Talks Monday May 19, 2014

Present and Future of axion searches: the International AXion Observatory IAXO

By Igor G. Irastorza (Zaragoza)
Axions are a natural consequence of the Peccei-Quinn mechanism, the most compelling solution to the strong-CP problem. Similar axion-like particles (ALPs) also appear in a number of possible extensions of the Standard Model, notably in string theories. Both axions and ALPs are very well motivated candidates for the Dark Matter, and are subject of increasing interest by experimentalists. I will present the different experimental strategies to detect these particles, and I will briefly review their current status and future prospects. Then I will focus on the International Axion Observatory (IAXO), the most ambitious project currently under consideration. IAXO will be a fourth generation axion helioscope. As its primary physics goal, IAXO will look for axions or ALPs originating in the Sun via the Primakoff conversion of the solar plasma photons. In terms of signal to background ratio, IAXO will be about 4-5 orders of magnitude more sensitive than CAST, the most sensitive axion helioscope to- date. IAXO has also potential to host additional detection setups. Most interestingly, the large magnetic volume of IAXO could be used to detect relic axion or ALPs potentially composing the galactic halo of Dark Matter. IAXO has the potential to serve as a multi-purpose facility for generic axion and ALP research in the next decade.

Mass and Lattice QCD

By Laurent Lellouch (CPT Marseille, CNRS & Aix-Marseille U)
While elementary particles get their mass from a Higgs-like mechanism, the origin of the mass of ordinary matter is non-perturbative, strong interaction dynamics. This has been unambiguously confirmed in the last few years, thanks to the tremendous progress undergone by ab-initio calculations in lattice quantum chromodynamics (QCD). After reviewing this progress, I will show how lattice QCD is allowing us to investigate many different aspects of mass. These applications range from providing the theory required to “measure” quark masses, to explaining important aspects of the stability of ordinary matter, through determining the coupling of possible WIMP dark matter, which could constitute 85% of the total matter in the universe, to the ordinary matter of WIMP detectors.

Right-Handed Neutrinos as the Origin of the Electroweak Scale

By Hooman Davoudiasl (BNL)
The insular nature of the Standard Model may be explained if the Higgs potential is only sensitive to quantum corrections from masses associated with physical states. Starting from a scale-free electroweak sector, we show that heavy right-handed neutrinos can be the origin of mass for scalar dark matter, in a framework with two scalar doublets. In turn, below the mass of heavy neutrinos, the dark matter sector sets the scale of electroweak symmetry breaking. The successive transmission of mass scale from right-handed neutrinos occurs at the quantum level. This framework includes all the necessary ingredients to provide a viable dark matter candidate, realistic light neutrino masses, and the baryon asymmetry of the Universe via thermal leptogenesis.

Do interacting UV fixed points exist, and if so, what can we do with them?

The talk by Daniel Litim (Sussex) will be available later.

From lowe energy neutrino data to mass models (and back) with leptogenesis.

By Pasquale Di Bari (Southampton)
I will discuss how imposing the successful leptogenesis bound one obtains interesting constraints on those high energy parameters characterising right-handed (RH) neutrino parameters in the see-saw mechanism. This provides a useful guidance among the many existing models especially when a condition of independence of the initial conditions is further added (strong thermal leptogenesis condition). In this case a particular (hierarchical) RH neutrino mass spectrum is singled out that, interestingly, is realised in SO(10)-inspired models. I will also discuss how the strong thermal leptogenesis condition by itself (i.e. model independently) favours values of the absolute neutrino mass scale that imply deviations from the hierarchical limit that might be experimentally detected in absolute neutrino mass scale experiments, especially in the case of normally ordered light neutrinos. In this way, leptogenesis acts as an important tool to connect low energy neutrino data to models.

Non-perturbative propagators and running coupling in the conformal window of QCD

By Reinhard Alkofer (Graz)
QCD with a relatively large number of fundamentally charged quark flavours in the chiral limit is considered. A self-consistent solution of the quark, gluon and ghost propagator Dyson-Schwinger equations in Landau gauge exhibits a phase transition. Above the critical number of fermion flavours the non-perturbative running coupling develops a plateau over a wide momentum range, and the propagators follow a power law behaviour for these momenta. Hereby, the critical number of quark flavours depends crucially on the non-perturbative tensor structures of the quark-gluon vertex.

Lattice Radial Quantization

By George T. Fleming (Yale University)
I present the current status of a program to formulate D-dimensional strongly-coupled relativistic quantum field theories on lattice discretizations of cylindrical manifolds whose cross-section is a (D-1)-dimensional sphere. Critical points in such theories should correspond to Conformal Field Theories (CFTs) if the full rotational symmetry of the sphere can be recovered in the continuum limit. If the formulation is successful, studying these CFTs should be numerically much less expensive that the equivalent calculations on a D-dimensional torus.

Conformal bootstrap in 4D

The talk by Oleg Antipin (INFN) will be available later.