Neutrinoless double beta decay in effective field theory

We discuss the contributions of lepton-number-violating sources to neutrinoless double beta decay ($0\nu\beta\beta$). Assuming that these sources arise at scales well above the electroweak scale, they can be described within an effective field theory. Here, we outline the steps required to express the $0\nu\beta\beta$ half-life in terms of the effective interactions, focusing on the dimension-five operator that induces a Majorana mass for the neutrinos. This process involves the evolution of the operators down to scales of a few GeV where they can be matched onto Chiral Perturbation Theory. The resulting Chiral Lagrangian can then used be to derive the lepton-number violating potential, which, in combination with many-body methods, gives the $0\nu\beta\beta$ half-life. We will show that consistent renormalization requires the inclusion of a new contact interaction at leading order in this potential. We also briefly comment on the constraints that can be set on the operators appearing beyond dimension five.Comment: Corrected referenc

High- and low-energy constraints on top-Higgs couplings

We study the five chirality-flipping interactions that appear in the top-Higgs sector at leading order in the standard model effective field theory. We consider constraints from collider observables, flavor physics, and electric-dipole-moment experiments. This analysis results in very competitive constraints from indirect observables when one considers a single coupling at a time. In addition, we discuss how these limits are affected in scenarios in which multiple top-Higgs interactions are generated at the scale of new physics.Comment: 7 pages, 1 figure. Contribution to the proceedings of the 9th International Workshop on the CKM Unitarity Triangle, 28 November - 3 December 201

Viability of minimal left-right models with discrete symmetries

We provide a systematic study of minimal left-right models that are invariant under $P$, $C$, and/or $CP$ transformations. Due to the high amount of symmetry such models are quite predictive in the amount and pattern of $CP$ violation they can produce or accommodate at lower energies. Using current experimental constraints some of the models can already be excluded. For this purpose we provide an overview of the experimental constraints on the different left-right symmetric models, considering bounds from colliders, meson-mixing and low-energy observables, such as beta decay and electric dipole moments. The features of the various Yukawa and Higgs sectors are discussed in detail. In particular, we give the Higgs potentials for each case, discuss the possible vacua and investigate the amount of fine-tuning present in these potentials. It turns out that all left-right models with $P$, $C$, and/or $CP$ symmetry have a high degree of fine-tuning, unless supplemented with mechanisms to suppress certain parameters. The models that are symmetric under both $P$ and $C$ are not in accordance with present observations, whereas the models with either $P$, $C$, or $CP$ symmetry can not be excluded by data yet. To further constrain and discriminate between the models measurements of $B$-meson observables at LHCb and $B$-factories will be especially important, while measurements of the EDMs of light nuclei in particular could provide complementary tests of the LRMs.Comment: Minor modifications, added references, matches published version in Nuclear Physics

Renormalization Group Running of Dimension-Six Sources of Parity and Time-Reversal Violation

We perform a systematic study of flavor-diagonal parity- and time-reversal-violating operators of dimension six which could arise from physics beyond the SM. We begin at the unknown high-energy scale where these operators originate. At this scale the operators are constrained by gauge invariance which has important consequences for the form of effective operators at lower energies. In particular for the four-quark operators. We calculate one-loop QCD and, when necessary, electroweak corrections to the operators and evolve them down to the electroweak scale and subsequently to hadronic scales. We find that for most operators QCD corrections are not particularly significant. We derive a set of operators at low energy which is expected to dominate hadronic and nuclear EDMs due to physics beyond the SM and obtain quantitative relations between these operators and the original dimension-six operators at the high-energy scale. We use the limit on the neutron EDM to set bounds on the dimension-six operators.Comment: Matches published version, 35 pages, 6 figures, minor correction

T violation in radiative β\beta decay and electric dipole moments

In radiative $\beta$ decay, $T$ violation can be studied through a spin-independent $T$-odd correlation. We consider contributions to this correlation by beyond the standard model (BSM) sources of $T$-violation, arising above the electroweak scale. At the same time such sources, parametrized by dimension-6 operators, can induce electric dipole moments (EDMs). As a consequence, the manifestations of the $T$-odd BSM physics in radiative $\beta$ decay and EDMs are not independent. Here we exploit this connection to show that current EDM bounds already strongly constrain the spin-independent $T$-odd correlation in radiative $\beta$ decay.Comment: 11 pages, 2 figure

NLO QCD corrections to SM-EFT dilepton and electroweak Higgs boson production, matched to parton shower in POWHEG

We discuss the Standard Model Effective Field Theory (SM-EFT) contributions to neutral- and charge-current Drell-Yan production, associated production of the Higgs and a vector boson, and Higgs boson production via vector boson fusion. We consider all the dimension-six SM-EFT operators that contribute to these processes at leading order, include next-to-leading order QCD corrections, and interface them with parton showering and hadronization in Pythia8 according to the POWHEG method. We discuss existing constraints on the coefficients of dimension-six operators and identify differential and angular distributions that can differentiate between different effective operators, pointing to specific features of Beyond-the-Standard-Model physics.Comment: 42 pages, 8 Figure