QCD corrections to BB-meson mixing at two loops and beyond

We report on the updated theoretical predictions for the width difference $ΔΓ_s$ and the flavor-specific CP asymmetry $a^s_{fs}$ in the $B_s−\bar{B}_s$ mixing. Working at leading power in the Heavy Quark Expansion we evaluated all previously unknown two-loop contributions to this observable, which marks an important step in the task of reducing uncomfortably large scale uncertainties stemming from uncalculated QCD corrections. Our new the Standard-Model prediction for the ratio of the width and mass differences in the $\overline{MS}$ scheme reads $ΔΓ_s/ΔM_s=(5.20±0.69)⋅10^{−3}$

NNLO QCD corrections to B-meson mixing

We report on the calculation of next-to-next-to-leading order (NNLO) QCD corrections to the width difference $\Delta \Gamma_s$ in the neutral B-meson mixing process $B^0_s$ - $\bar{B}^0_s$. These contributions represent an important step in the task of reducing the existing large perturbative errors in the theory prediction for $\Delta \Gamma_s$ and approaching the current experimental uncertainties. We explain the theoretical framework employed in this computation and point out important subtleties in the treatment of evanescent operators and the renormalization. Part of our new results is already available in the literature, while the remaining pieces are expected to be published later this year

NNLO QCD corrections to B-meson mixing

We report on the calculation of next-to-next-to-leading order (NNLO) QCD corrections to the width difference $\Delta \Gamma_s$ in the neutral B-meson mixing process $B^0_s$ - $\bar{B}^0_s$. These contributions represent an important step in the task of reducing the existing large perturbative errors in the theory prediction for $\Delta \Gamma_s$ and approaching the current experimental uncertainties. We explain the theoretical framework employed in this computation and point out important subtleties in the treatment of evanescent operators and the renormalization. Part of our new results is already available in the literature, while the remaining pieces are expected to be published later this year

Non-relativistic and potential non-relativistic effective field theories for scalar mediators

Yukawa-type interactions between heavy Dirac fermions and a scalar field are a common ingredient in various extensions of the Standard Model. Despite of that, the non-relativistic limit of the scalar Yukawa theory has not yet been studied in full generality in a rigorous and model-independent way. In this paper we intend to fill this gap by initiating a series of investigations that make use of modern effective field theory (EFT) techniques. In particular, we aim at constructing suitable non-relativistic and potential non-relativistic EFTs of Yukawa interactions (denoted as NRY and pNRY respectively) in close analogy to the well known and phenomenologically successful non-relativistic QCD (NRQCD) and potential non-relativistic QCD (pNRQCD). The phenomenological motivation for our study lies in the possibility to explain the existing cosmological observations by introducing heavy fermionic dark matter particles that interact with each other by exchanging a light scalar mediator. A systematic study of this compelling scenario in the framework of non-relativistic EFTs (NREFTs) constitutes the main novelty of our approach as compared to the existing studies.Comment: 50 pages, 12 figure

Bound-state formation, dissociation and decays of darkonium with potential non-relativistic Yukawa theory for scalar and pseudoscalar mediators

Dark matter models with light mediators featuring sizable interactions among dark particles enjoy an increasing attention in the model building community due to the elegance with which they can potentially explain the scaling relations governing galactic halos and clusters of galaxies. In the present work we continue our study of such models using non-relativistic and potential non-relativistic effective field theories (NREFTs and pNREFTs) and explore the properties of a Yukawa-type model with scalar and pseudoscalar interactions between a low-energetic scalar mediator and heavy dark matter fermions. In particular, we make first steps towards the formulation of such theories at finite temperature by providing the thermal bound-state formation rate and the thermal break-up of bound states from the self-energies of the dark-pair fields, that interact with the thermal environment. We estimate numerically bound-state effects on the dark matter energy density, that provide up to a 35% correction depending on the relative size of the model couplings