Search for neutrinoless double beta decay is one of the primary probes to understand the neutrino nature. Its discovery implies lepton-number violation, confirming the Majorana neutrino mass which is realized by introducing sterile neutrinos. The theoretical approach requires somewhat complicated processes connecting fundamental interactions to those at hadronic and nuclear levels. In this...
$CP$-violating interactions at quark level generate $CP$-violating nuclear forces which could be revealed by looking at the presence of a permanent nuclear electric dipole moments. Within the framework of chiral effective field theory and thanks to the modern $ab-initio$ techniques, it is possible to perform realistic calculation for the electric dipole moment of the light nuclei. In this work...
We describe examples of renormalizable field theories where the breaking of chiral symmetry at the UV cutoff leaves behind at low energy dynamically generated elementary particle masses in a way alternative to the Higgs mechanism. In this scenario 1) the scale of the elementary particle masses is set by the RGI scale of the theory 2) masses are kept ``small'' owing to an enhanced chiral...
What is the nature of so-called Dark Matter, and does it interact with regular matter except through gravity? For example, direct detection experiments aim to answer this question. Propagating measurements (or constraints) to the fundamental theory requires bridging several scales—from target nucleus to individual nucleons to the level of quarks & gluons and beyond. However, the sheer number...
I will review recent developments in rare and radiative kaon decays from the theory side, with emphasis on those modes that are actively analyzed by the experimental collaborations.
In this talk we present a relativistic and model-independent method to analytically derive electromagnetic finite-size effects beyond the point-like approximation. Structure-dependence appears in terms of physical form-factors and derivatives thereof. The values of these physical quantities can be taken either from experimental measurements or auxiliary lattice calculations. We first apply our...
The quantitative understanding of hadron structure holds the key to the interpretation of current and future experiments in particle, hadron and nuclear physics, which provide crucial information for the search for New Physics. In this talk I review the status of lattice QCD calculations of structural properties of the nucleon, focussing on the determination of electromagnetic and axial form...
The axial, scalar, and tensor charges of the nucleon are important observables needed to interpret the results of many experiments and probe new physics. In this talk, I will present our recent lattice QCD calculations of the nucleon charges and discuss systematic uncertainties associated with the excited state contamination.
Recently, we established an $N\bar N$ potential within chiral
effective field theory [1] which is fitted to up-to-date $N\bar N$
phase shifts and inelasticities provided by a recently published
phase-shift analysis of available $p \bar p$ scattering data [2].
The quality of the description of those phase shifts but also
of $p \bar p$ observables will be discussed.
As an application of...
Charged particle multiplicity distributions in positron-proton deep inelastic scattering at a centre-of-mass energy $\sqrt{s}=319$ GeV are measured. The data are collected with the H1 detector at HERA corresponding to an integrated luminosity of $136$ pb$^{-1}$. Charged particle multiplicities are measured as a function of photon virtuality $Q^2$, inelasticity $y$ and pseudorapidity $\eta$ in...
Effective Field Theories (EFTs) organized as derivative expansions are controllable as long as the energy of the interacting particles remains small, as they do not respect exact elastic unitarity. This limits their predictive power towards new physics at a higher scale if small separations from the Standard Model are found at the LHC or elsewhere.
This is exemplified by ChPT: though...
In this talk I will provide a brief review of the different results and approaches used in estimating the contributions to the anomalous magnetic moment of the muon, with emphasis on the hadronic contributions. The presentation will follow the review released by the Muon g-2 Theory Initiative.
Model-independent short-distance constraints allow for a reduction of theoretical uncertainties associated to the analytic evaluation of Hadronic Light by Light contributions to muon g-2. In this talk we focus on the region where the three loop virtualities are large. Even when the fourth photon leg is soft, we show how a precise Operator Product Expansion can be applied in that region. The...
In recent years, significant progress in the calculation of the HLbL contribution to the anomalous magnetic moment of the muon has been achieved both with data-driven methods and in lattice QCD. In the talk I will discuss current developments aimed at controlling HLbL scattering at the level of 10%, as required for the final precision of the Fermilab E989 experiment.
The concept of lepton universality, where the muon and tau particles are simply heavier copies of the electron, is a key prediction in the Standard Model (SM). In models beyond the SM, lepton universality can be naturally violated with new physics particles that couple preferentially to the second and third generation leptons. Over the last few years, several hints of lepton universality...
Motivated by the experimental patterns of lepton-universality breaking, we present a simple strategy based on ratios of leptonic and semileptonic B decays which decouple the CKM elements $|V_{ub}|$ and $|V_{cb}|$ from the short-distance coefficients of (pseudo)-scalar, vector and tensor operator contributions associated with $b \rightarrow u$ and $b \rightarrow c$ transitions. We illustrate...
In the context of warped five-dimensional models formulated to understand the physics beyond the Standard Model (SM), we will discuss the prediction of a continuum of Kaluza-Klein modes, on top of the SM zero modes, with different mass gaps for all particles: gauge bosons, fermions, graviton, radion and Higgs boson. In particular, we will study the existence of resonance effects in gauge...
The existence of CP violation in the decays of strange and beauty mesons is very well established experimentally. On the contrary, CP violation in the decays of charmed particles has been elusive for a long time for the experimentalists and has been observed before for the first time in 2018 by the LHCb experiment. During the LHC Run 1 and Run 2, the LHCb collaboration has collected a huge...
We discuss the theoretical implications of the recent discovery of CP violation in two-body charm decays at LHCb. The 2019 breakthrough follows the first discovery of CP violation in kaon decays in 1964 and in beauty decays in 2001. We illustrate that charm physics has the potential for the discovery of physics beyond the Standard Model and will teach us also more about non-perturbative low-energy QCD.
