The main goal of this workshop is to bring together a group of researchers with common interests from the different countries participating in the COST action "Connecting insights in fundamental physics", allowing them to share experiences and to discuss possible collaborations in the field of Higgs and Flavour Physics, including Neutrino Physics. This workshop will also provide an opportunity to present the GAMBIT collaboration and some of the existing modules for different calculations.
The emphasis of the workshop is on the topics:
The afternoon of the 17th of January will be dedicated to the code GAMBIT, including a tutorial.
A seminar for the general public will take place late in one of the afternoons.
The registration fee is 200 euros (100 euros for students and postdocs) and 70 euros for accompanying persons (for more details on registration see here).
Local Organising Committee:
COST Organising Committee:
The EW vacuum lifetime is extremely sensitive to unknown (although necessarily present) high energy new physics. The latter can enormously lower the EW vacuum lifetime, posing a serious problem for the stability of our universe. After presenting the general issue of vacuum stability, and the reasons why new physics can be so highly destabilizing, I will discuss symmetries, physical models, as well as model-independent effects, that can provide the stabilization mechanism protecting our universe from decaying.
Scenarios with a dark sector involving a light gauge boson have attracted considerable attention recently. The kinetic mixing of such a "dark photon" with the standard photon has to satisfy very stringent experimental bounds, which are violated in the simplest case where kinetic mixing is generated at the one-loop level. I will present scenarios where a sufficiently small kinetic mixing can be obtained.
After discussing the general form of a Majorana neutrino mass matrix I will introduce a master parametrization for the Yukawa matrices in agreement with neutrino oscillation data. This parametrization extends previous results in the literature and can be used for any model that induces Majorana neutrino masses with the seesaw mechanism (with the only exception of the type-II seesaw). The application of the master parametrization will be illustrated in several example models, with special focus on their lepton flavor violating phenomenology.
Neutrinoless double beta decay can significantly help to shed light on the issue of non-zero neutrino mass, as observation of this lepton number violating process would imply neutrinos are Majorana particles. However, the underlying interaction does not have to be as simple as the standard neutrino mass mechanism. The entire variety of neutrinoless double beta decay mechanisms can be approached effectively. In this talk I will focus on a theoretical description of short-range effective contributions to neutrinoless double beta decay, which are equivalent to 9-dimensional effective operators as well as a novel mode with a Majoron-like scalar particle emitted in the decay.
I will first review the kind of constraints and requirements coming from leptogenesis on flavour models and then focus on those I consider more attractive showing their predictions and how we can test them. In particular I will show the important role played by unknowns in the leptonic mixing matrix in combination with the information from absolute neutrino mass scale experiments: on the sum of neutrino masses from cosmological observations and on the low neutrino mass matrix ee entry from neutrino less double beta decay experiments.
I discuss how Yukawa alignment in Multi-Higgs models can arise from flavour symmetries.
Contrary to common perception, we show that the current Higgs data does not eliminate the possibility of a sequential fourth generation that gets its mass through the same Higgs mechanism as the first three generations. The inability to fix the sign of the bottom-quark Yukawa coupling from the available data plays a crucial role in accommodating a chiral fourth generation which is consistent with the bounds on the Higgs signal strengths. We show that the effects of such a fourth generation can remain completely hidden not only in the production of the Higgs boson through gluon fusion but also to its subsequent decay to two photons and Z-photon. This, however, is feasible only if the scalar sector of the standard model is extended. We also provide a practical example illustrating how our general prescription can be embedded in a realistic model.
We investigate the muon anomalous magnetic moment, the μ→eγ branching ratio and the μ→e conversion rate in the nuclei from the point of view of the planned μ→e conversion experiments. In the MSSM these processes are strongly correlated through tanβ enhanced contributions. We demonstrate how in the Minimal R-symmetric Supersymmetric Standard Model the μ→eγ branching ratio and the μ→e conversion rate in the nuclei give distinct bounds on the parameter space. We also consider the supersymmetric contributions to the muon anomalous magnetic moment, generated by a subset of topologies contributing to the LFV observables. We briefly discuss the generic implementation of the aforementioned observables into the FlexibleSUSY spectrum-generator generator. Looking at the current μ→eγ searches, the analysis points to the need of constructing a dedicated μ→e conversion experiment to cover as large parameter space as possible in the non-minimal supersymmetric models.
In a model containing two scalar doublets and a scalar singlet with a specific discrete symmetry, spontaneous symmetry breaking yields Standard Model-like phenomenology, as well as a hidden scalar sector which provides a viable dark matter candidate. CP violation in the scalar sector occurs exclusively in the hidden sector, and possible experimental signatures of this CP violation will be presented.
Compactifications of heterotic M-theory are shown to provide solutions to the weak-scale hierarchy problem as a consequence of warped large extra dimensions. They allow a description that is reminiscent of the so-called continuous clockwork mechanism. The models constructed here cover a new region of clockwork parameter space and exhibit unexplored spectra and couplings of Kaluza-Klein modes. Relations to previously proposed models as well as roles played by vector multiplets and the universal hypermultiplet in 5D-supergravity are also discussed.
We discuss the appearance of various topological defects in SO(10) grand unification and how some may survive cosmic inflation. Dark matter candidates are briefly discussed.
The origin of masses and mixings of the three families of fermions remains one of the main problems of the Standard Model. Flavor symmetries provide a compelling way to explain these of arbitrary parameters in the Yukawa sector. In Supersymmetric extensions of the Standard Model, where the mediation of SUSY breaking occurs at scales larger than the breaking of flavor, this symmetry must be respected not only by the Yukawas of the superpotential, but by the soft-breaking masses and trilinear terms as well. In this case, even starting with completely flavor blind soft-breaking in the full theory at high scales, the low-energy sfermion mass matrices and trilinear terms of the effective theory, obtained upon integrating out the heavy mediator fields, are strongly non-universal. We explore the phenomenology of several SUSY flavor models after the latest LHC searches for new physics.
I am going to discuss properties of heavy Higgs bosons in the alignment limit of a generic 2HDM. This model constitutes a simple and attractive extension of the SM that is consistent with the observation of the SM-like Higgs boson and precision electroweak observables, while providing potential new sources of CP-violation.
The Inert Doublet Model is an intriguing extension of the Standard Model that provides a dark matter candidate and is yet only marginally constrained by current collider data. I will discuss prospects of investigation this model at the LC as well as future e+e- colliders, and present the most recent constraints on the models parameter space.
We derive the mass exclusion limits for the hypothetical vector resonances of a strongly interacting extension of the Standard Model using the most recent upper bounds on the cross sections for various resonance production processes. The SU(2)_L+R triplet of the vector resonances under consideration is embedded into the effective Lagrangian based on the non-linear sigma model with the 125-GeV SU(2) L+R scalar singlet.
The Standard Model fields can interact through non-renormalizable operators, the simplest of which is the one mentioned by Weinberg, with dimension 5. The list of all such operators up to dimension 6 is known and, since the last few years, so is the number of all effective interactions up to dimension 15. However, counting operators and listing them explicitly are different things. In this presentation I will talk about the challenges associated with writing down the non-renormalizable interactions of Standard Model fields beyond dimension 6.
A viable Two Higgs Doublet Model with CP violation of spontaneous origin is presented. In this model, based on a generalised Branco-Grimus-Lavoura model with a flavoured $Z_2$ symmetry, the lagrangian respects CP invariance, while the vacuum has a CP violating phase, which is able to generate a complex CKM matrix. Scalar mediated flavour changing neutral couplings are analysed, stressing the connection between the generation of a complex CKM matrix and the unavoidable presence of scalar FCNC. The scalar sector is also presented in detail, showing that the new scalars are necessarily lighter than 1 TeV. Finally, a phenomenological analysis of the model including the most relevant constraints is discussed, exploring, in particular, definite implications for the observation of New Physics signals.
In view of several hints of lepton non universality, observed in B meson decays, we find that with a minimal modification to the SM in terms of an effective theory, the charged as well as neutral current anomalies can well be explained by introducing just two new parameters. This class of operators predict some interesting signatures both in the context of B decays as well as high-energy collisions.
In the context of the minimal type-I seesaw model, we study the implications of considering maximally-restricted texture-zero patterns in the lepton Yukawa coupling and mass matrices. All possible patterns are analysed in the light of the most recent neutrino oscillation data and, in case of compatibility, predictions for leptonic CP violation, the effective mass relevant for neutrinoless double-beta decay, and the baryon asymmetry of the Universe are obtained.
A minimal extension to the Standard Model with three positive chirality neutrinos is devised, under the Seesaw Type I framework. A novel parametrization is exploited, which enables to control all deviations from unitarity through a single $3 \times 3$ matrix, which is denoted by $X$, that also connects the mixing of the light and heavy neutrinos in the context of type I seesaw. This parametrization is adequate for a general and exact treatment, independent of the scale of the right handed neutrino mass term. Examples with sizeable deviations from unitarity and heavy neutrinos with not very large masses are presented. The problem of possibly large one-loop mass corrections to the light neutrino masses is taken into account.
The recent intriguing hints for new physics in semi-leptonic B decays point towards lepton flavor universality violating extensions of the SM. Prime candidates for such new particles are leptoquarks which can provide the desired effects. After reviewing the current experimental and theoretical situation, I discuss the phenomenology of the vector leptoquark SU(1) singlet with was proposed already a long time ago in the context of the famous Pati-Salam model.
Summary of present status of oscillation parameters, current improvements and discussion on future plans will be prasentad. Some details about measurement metodelogy and experimental limitations will also be given.
We have calculated the W-loop SM contribution to the amplitude of the decay H → Z + γ and also for H → γ + γ in the Rξ-gauge using dimensional regularization (DimReg) and in the unitary gauge through the dispersion method. We show that the results of the calculations with DimReg and the dispersion method, adopting the boundary condition at the limit MW → 0 defined by the Goldstone boson equivalence theorem (GBET), completely coincide. This implies that DimReg is compatible with the dispersion method obeying the GBET. Thus, our results also agree with the “classical” ones. The advantage of the applied dispersion method is that we work with finite quantities and no regularization is required.
The second data taking period of the LHC has just ended, having delivered about 150/fb worth of pp collisions to ATLAS/CMS at the record energy of 13TeV, as well as collisions involving heavy ions. This exceeds by a factor of 5 the amount of data recorded during the first datataking period. With only part of these data having been analyzed, a good number of results have been already extracted, which resulted in considerable jumps in sensitivity. I will present a selection of recent results obtained with CMS.
We consider an anomaly free extension of the standard model gauge group GSM by an abelian group to GSM ⊗ U(1)Z. The condition of anomaly cancellation is known to fix the Z-charges of the particles, but two. We fix one remaining charge by allowing for all possible Yukawa interactions the known left handed neutrinos and new right-handed ones that obtain their masses through interaction with a new scalar field whose vacuum is broken spontaneously. We discuss some of the possible consequences of the model and ways of constraining the parameter space.
With the first Higgs doublet established, a second doublet is rather likely. We give several arguments why the usual Z2 symmetry that removes extra Yukawa couplings should be discarded. We then show that this provides a rather robust mechanism for electroweak baryogenesis, by the combined presence of lambda_t ~ 1 and Im(rho_tt) ~ 1, where rho_tt is the extra top Yukawa, while rho_tc could provide a backup mechanism. We show that the prerequisite of Higgs quartic couplings, eta_i, also of O(1), can relatively easily give rise to the observed approximate alignment, that the observed h(125) appear so close to SM-Higgs. As a most likely next New Physics, extra Yukawas, whether flavor changing or conserving, are numerous, but they are quite well hidden by flavor hierarchies, alignment, and heavy Higgs at 500 GeV or higher. The remainder of the talk discusses where and how to unveil these couplings.
I discuss the production of a single top quark in the t-channel and its subsequent decay is studied at NLO accuracy in QCD, augmented with the relevant dimension-6 effective operators from the Standard Model Effective Theory. I show results for various kinematic and angular distributions for the LHC at 13 TeV, in order to assess the sensitivity to these operators, both with and without the top quark narrow width approximation. I show also the amount of sensitivity to a possible extra source of CP violation due to the weak dipole operator.
We address the B-physics anomalies within a two scalar leptoquark model. The low-energy flavor structure of our set-up originates from two SU(5) operators that relate Yukawa couplings of the two leptoquarks. The proposed scenario has a UV completion, can accommodate all measured lepton flavor universality ratios in B-meson decays, is consistent with related flavor observables, and is compatible with direct searches at the LHC. We provide prospects for future discoveries of the two light leptoquarks at the LHC and predict several yet-to-be-measured flavor observables.
The current flavour anomalies seem to indicate lepton flavour non-universality. To explain all the anomalies simultaneously, it is believed that exotic new physics beyond the Standard Model is needed, such as the existence of leptoquarks etc. I shall show that simultaneous explanation to all current flavour anomalies can be obtained in three Higgs doublet models. The prediction of this scenario is an existence of GeV scale right-handed neutrinos. Thus the current anomalies might be connected to extra Higgses and to low scale leptogenesis.
The most powerful approach for assessing the level of agreement between a new theory and experimental results is to perform a "global fit" -- a comprehensive and statistically rigorous comparison of theory predictions against all the available data. In this talk I will give an introduction to BSM global fits and the software tool GAMBIT, an open-source package for performing large-scale global fits. The presentation will be followed by a demonstration and tutorial on how to use GAMBIT.
The occurrence of flavour-violating decays of hadrons and leptons into light axion-like particles is a generic consequence of spontaneously-broken global U(1) symmetries with flavour non-universal charges, and a powerful probe of such kind of scenarios. A well-motivated example is the flavour-violating QCD axion arising in the context of a Froggatt-Nielsen model of fermion masses and mixing. I will discuss both the latter specific case and the more generic setup with a focus on their phenomenology at flavour experiments.
I review scenarii in which the particles that account for the dark matter in the universe interact only through their couplings with the Higgs sector of the theory, the so-called Higgs-portal models. I summarize and update the present constraints and future prospects from the collider physics perspective and compare them to what can be obtained from the cosmological relic abundance as well as from direct and indirect dark matter detection in astroparticle physics experiments.