FLASY 2022 - 9th Workshop on Flavour Symmetries and Consequences in Accelerators and Cosmology

27 Jun 2022, 08:00 → 1 Jul 2022, 21:00 Europe/Lisbon

IST Congress Centre (Instituto Superior Técnico, Lisbon, Portugal)

FLASY2022 is the 9th Workshop on Flavour Symmetries and Consequences in Accelerators and Cosmology.

The workshop is intended to bring together researchers in the field of flavour symmetries, neutrino physics, Higgs physics, CP violation, accelerator physics and cosmology/astroparticle physics to present new results, stimulate discussion and new collaborations.

FLASY2022 will be held at Instituto Superior Técnico-IST Congress Centre (Av. Rovisco Pais 1, Lisbon, Portugal) from the 27th of June to the 1st of July and will be an in-person event. 

Local Organising Committee:	Scientific Secretariat:	Secretariat:
Gustavo Branco Ricardo Felipe Filipe Joaquim (Chair) João Penedo M. (Gui) N. Rebelo Joaquim Silva-Marcos Ivo Varzielas	João Alves     Débora Barreiros Henrique Câmara Bernardo Gonçalves Anton Kuncinas Miguel Levy Pedro Pereira João Seabra	Dulce Conceição    Sandra Oliveira

International Advisory Board:
S. Antusch (University of Basel) A. Aranda (U. Colima, DCPIHEP) G. Bhattacharyya (Saha Institute Kolkata) G. Burdman (U. São Paulo) Gui-Jun Ding (USTC, Hefei) Xiao-Gang He (TDLI Shanghai/NTU Taiwan) G. Hiller (U. Dortmund) S. Jaeger (University of Sussex) T. Kephart (U. Vanderbilt) S. King (U. Southampton)	S. Kovalenko (U. Andres Bello, Chile) M. Lindner (Max Planck Inst. Heidelberg) E. Ma (University of California Riverside) M. Mondragon (UNAM, Mexico) S. Morisi (Naples U.) Y. Nir (Weizmann Institute) H. Päs (T. U. Dortmund) D. Straub (T. U. Munich) M. Tanimoto (Niigata U.) J. W. F. Valle (IFIC/CSIC-Universidad de Valencia)

Supported by:

BookingForm_FLASY HI.pdf

FLASY2022 Info.pdf

posterFLASY.pdf

Turim hotel booking form

Monday, 27 June

08:30 → 09:15 Registration

09:15 → 09:30 Welcoming

09:30 → 10:30 Morning Session

Convener: Gustavo Branco

09:30 Overview of the three-neutrino oscillation picture

This talk will present the current status of global analyses of neutrino oscillation data in the three-flavor framework. I will discuss the hints in favor of normal mass ordering and maximal CP violation and the tensions that appear from the combination of different data samples. I will also comment on future opportunities to improve our knowledge of the oscillation picture as well as on its robustness in the presence of new physics beyond the Standard Model.

Speaker: Mariam Tórtola

MTortola-FLASY2022.pdf

10:00 Lepton flavor phenomena in modular symmetry

We discuss the lepton flavor violation (LFV), the leptonic magnetic moments (g-2)
and the electric dipole moment (EDM) of the electron in the Standard-Model Effective Field Theory (SMEFT) with the modular symmetry. We take the level 3 finite modular group for the flavor symmetry, and discuss the dipole operators at nearby fixed point $\tau=i$, where observed lepton masses and mixing angles are well reproduced.

Speaker: MORIMITSU TANIMOTO

Tanimoto-FLASY2022.pdf

10:30 → 11:00 Coffee Break

11:00 → 12:30 Morning Session

Convener: Jorge Romão

11:00 Automorphic forms and fermion masses

Symmetry principles have long been applied to the flavour puzzle. In a bottom-up approach, the variety of possible symmetry groups and symmetry breaking sectors is huge, the predictability is reduced and the number of allowed models diverges. A relatively well-motivated and more constrained framework is provided by supersymmetric theories where a discrete subgroup Γ of a non-compact Lie group G plays the role of flavour symmetry and the symmetry breaking sector spans a coset space G/K, K being a compact subgroup of G. For a general choice of G, K, Γ and a generic matter content, I show how to construct a minimal K ̈ahler potential and a general superpotential, for both rigid and local N = 1 supersymmetric theories.

Speaker: Ferruccio Feruglio

Feruglio_FLASY2022.pdf

11:30 UV origin of modular flavor symmetries

Modular flavor symmetries are a new and exciting approach to the flavor problem. Simple, successful models have been proposed in the bottom-up approach. In this talk the geometric interpretation and intuition of modular flavor symmetries will be provided by deriving modular flavor symmetries from a torus. It will also be discussed how they emerge from UV complete string compactifications.

Speaker: Michael Ratz

FLASY2022_Ratz.pdf

12:30 → 14:30 Lunch Break

14:30 → 16:00 Afternoon Session

Convener: Marc Sher

14:30 Revisiting puzzles in lifetimes of single charmed hadrons

We provide an extensive study of the lifetimes of singly charmed baryons and
mesons, within the heavy quark expansion with all known corrections included.
We give our predictions for lifetimes, lifetime ratios, and semileptonic branching ratios of singly charmed baryons. Our results accommodate the experimentally-favoured hierarchy of singly charmed baryon lifetimes
τ (Ξ0c)< τ (Λ+c) < τ (Ω0c) < τ (Ξ+c) in contrast to earlier theoretical findings. Predictions for charmed meson lifetimes and semileptonic decay rates are in agreement with a recent comprehensive study and experimental results within uncertainties.

Speaker: Blaženka Melić (Rudjer Boskovic Institute)

Flasy2022_Lifetimes_Melic.pdf

15:00 Heavy neutral leptons as long-lived particles

Interest in searches for heavy neutral leptons (HNLs) has gained significant momentum over the past few years with the appearance of several proposals for new dedicated "far" detectors to search for long-lived particles at the LHC. In this talk, I will briefly discuss HNLs and their possible connection with neutrino masses. I will then introduce NRSMEFT, i.e. standard model effective theory extended with a "light" (i.e. mass around the electro-weak scale) right-handed neutrino. Based on two recent papers, I will discuss the prospects to discover HNLs in this setup at the high-luminosity LHC.

Speaker: Martin Hirsch

MH_Flasy22.pdf

15:30 B0 B0\bar entanglement for an ideal experiment on the direct CP violation gamma phase

B0 B0\bar entanglement offers a conceptual alternative to the single charged B-decay asymmetry for the measurement of the direct CP violating
gamma phase. With f =J/PsiK_L; J/PsiK_S and g =(PiPi)0; (Rho_LRho_L)0 the 16 time-ordered double decay rate Intensities to (f; g) depend on the relative phase between the the f- and g-decay amplitudes given by gamma at tree-level. Several constraining consistencies appear. An intrinsic accuracy of the method at the level of 1º could be achievable at Belle-II with an improved determination of the penguin amplitude to g-channels from existing facilities.

Speaker: Francisco J. Botella (Univ. of Valencia and CSIC (ES))

FLASY_Botella_2022_1.pdf

16:00 → 16:30 Coffee Break

16:30 → 18:30 Afternoon Session

Convener: Mariam Tórtola

16:30 Elusive signals with anomaly detection

Elusive signals of new particles may well be hidden in LHC data. Because the mass of the new particles is unknown, as well as the specific characteristics of the signals, anomaly detection methods are quite valuable to bring these signals to light.

Speaker: Juan Antonio Aguilar Saavedra (Consejo Superior de Investigaciones Cientificas (CSIC) (ES))

SOFIE.pdf

17:00 Status of the R(D(*)) anomaly and complementary LHC probes

I will briefly review the current status of the anomaly in the lepton flavour universality ratios R(D(*)). Subsequently I will discuss ooportunities to probe the underlying New Physics with targeted LHC searches.

Speaker: Monika Blanke (Karlsruhe Institute of Technology)

Blanke-FLASY2022.pdf

17:30 On the interplay between flavour anomalies and neutrino properties

A minimal extension of the Standard Model (SM) featuring two scalar leptoquarks, an SU(2) doublet with hypercharge 1/6 and a singlet with hypercharge 1/3, is proposed as an economical benchmark model for studies of an interplay between flavour physics anomalies and properties of the neutrino sector. The presence of such type of leptoquarks radiatively generates neutrino masses and offers a simultaneous explanation for the current B-physics anomalies involving $b \to s \ell \ell$ and $b \to c \ell \nu_{\ell} $ decays. The model can also accommodate both the muon magnetic moment and the recently reported W boson mass anomalies, while complying with the most stringent lepton flavour violating observables.

Speaker: António Morais (University of Aveiro)

LQs-2.pdf

18:00 (g-2) and lepton flavor violation in low scale flavor symmetries

Low-energy flavour symmetries could contribute to the observed muon anomalous magnetic moment discrepancy. However, the stringent experimental bound on $\mu \to e\gamma$ is compatible with a simultaneous and sizable new physics contribution to the muon only if we assume a mostly (quasi)diagonal texture for models with a low flavor breaking scale. We propose a mechanism in which the realization of the (g-2)​ correction is manifestly related to the mass generation through a flavor symmetry. A radiative flavon correction to the fermion mass gives a contribution to the anomalous magnetic moment. We argue that many of the popular flavor models in the literature designed to explain the fermion masses and mixings are not suitable for reproducing the observed discrepancy in (g-2) which requires a delicate balance of maintaining a low flavor scale while simultaneously satisfying strong LFV constraints. Then, we present two concrete examples of models where a sub-TeV scale breaking of their respective T13 and A5 flavor symmetries is able to account for the recently observed discrepancy in the muon anomalous magnetic moment

Speaker: Oscar Manuel Vives Garcia (Univ. of Valencia and CSIC (ES))

g-2muT13Lisbon.pdf

19:30 → 22:00 Welcome Reception

Tuesday, 28 June

09:00 → 10:30 Morning Session

Convener: Francisco Botella

09:30 Flavor-Changing Neutral Currents in the Higgs Sector

In extensions of the Higgs sector, tree-level flavor-changing neutral currents will generally occur unless suppressed with a discrete symmetry. I'll review three different approaches to tree-level FCNC. The first, with a popular mass-matrix ansatz, appears to be under severe experimental challenge. The second involves models with "minimal flavor violation" - a common UV completion is the BGL models. Finally, so-called "flavorful models" will be discussed.

Speaker: Marc Sher

flasy2022.pdf

10:00 The Muon-Specific Model

The Muon-Specific Model is a version of the Two Higgs Doublet Model (2HDM) with a flavour-breaking symmetry that enhances or suppresses scalars' interactions with muons, compared with other 2HDMs. It was proposed by Abe, Sato, and Yagyu in 2017 in an attempt to explain the muon g-2 anomaly. We will review the main tenets of the model, including the interesting feature of it containaing flavour-violating interactions but no flavour-changing neutral currents. We will then proceed to show anaylse the predictions for the Higgs dimuon rate at the LHC within this model, as well as its contributions to the muon g-2 with added vector-like leptons.

Speaker: Pedro Ferreira

FLASY 2022.ppt

10:30 → 11:00 Coffee Break

11:00 → 12:30 Morning Session

Convener: Ferruccio Feruglio

11:00 Fermion Mass Hierarchies and Modulus Stabilisation in Modular-Invariant Models of Flavour

In modular-invariant models of flavour, hierarchical fermion mass matrices may
arise solely due to the proximity of the modulus $\tau$ to a point of
residual symmetry. This mechanism does not require flavon fields
and may produce viable fermion (charged-lepton and quark)
mass hierarchies without fine-tuning. Models of lepton flavour in which
the indicated idea is realised are presented.
The problem of modulus stabilisation in the framework of the modular
symmetry approach to the flavour problem is discussed as well.
By analysing simple UV-motivated
CP-invariant potentials for the modulus $\tau$ it is shown that a class of
these potentials has (non-fine-tuned) CP-breaking minima in the vicinity
of the point of residual $Z^{\rm ST}_3$
symmetry, $\tau \simeq e^{i 2\pi/3}$. Stabilising the modulus at these
novel minima breaks spontaneously the CP symmetry and
can naturally explain the mass hierarchies of charged leptons and
possibly of quarks.

Speaker: Serguey Petcov (INFN/SISSA, Trieste, Italy, and Kavli IPMU, Univ. of Tokyo, Japapn)

Petcov_FLASY2022.pdf

11:30 Precision of Model Predictions and Modular Flavor Symmetries

I will discuss the precision of predictions in models based on modular flavor symmetries aiming to address the fermion mass and mixing problem. I will describe a framework based on quasi-eclectic modular symmetries and its potential to reduce the theoretical uncertainties of model predictions.

Speaker: Mu-Chun Chen (University of California - Irvine)

2022FLASY_MCChen.pdf

12:00 Modular Flavor Symmetries and CP from the top down

The framework of compactified heterotic string theory offers consistent UV completions of the Standard Model of particle physics. In this approach, the existence of flavor symmetries beyond the Standard Model is imperative and the flavor symmetries can be derived from the top down. Such a derivation uncovers a unified origin of traditional discrete flavor symmetries, discrete modular flavor symmetries, discrete R symmetries of supersymmetry, as well as CP symmetry - altogether dubbed the eclectic flavor symmetry. I will illustrate how the eclectic flavor symmetry is unambiguously computed from the top-down construction, discuss the different arising sources of spontaneous flavor symmetry breaking, and expose possible lessons for bottom-up flavor model building. Finally, I will focus on one explicit example model that provides a successful fit to all available experimental data while giving rise to concrete predictions for so-far undetermined parameters.

Speaker: Andreas Trautner

Trautner_FLASY_22.pdf

12:30 → 14:30 Lunch Break

14:30 → 16:00 Afternoon Session

Convener: Blazenka Melic

14:30 Questioning New Physics in Rare Semileptonic B, D, and K decays

We investigate the consequences of deviations from the Standard Model observed in b→sμμ transitions for flavour-changing neutral-current processes involving down-type quarks and neutrinos. We derive the relevant Wilson coefficients within an effective field theory approach respecting the SM gauge symmetry, including right-handed currents, a flavour structure based on approximate U(2) symmetry, and assuming only SM-like light neutrinos. We discuss correlations among B→K(∗)νν and K→πνν branching ratios.
Assuming that NP has a CP-violating phase, we search for the observables which can test it. Then we discuss the correlation of New Physics in D→πll, D→πνν, K→πνν and K→π ll decays.

Speaker: Svjetlana Fajfer

Fajfer-FLASY.pdf

15:00 Semi-dark Higgs decays: sweeping the Higgs neutrino floor

We study exotic Higgs decays $h \to Z X$, with $X$ an invisible BSM particle, resulting in a semi-dark final state. Such exotic Higgs decays may occur in theories of axion-like-particles (ALPs), dark photons or pseudoscalar mediators between the SM and dark matter. The SM process $h\to Z\nu\bar{\nu}$ represents an irreducible ``Higgs neutrino floor'' background to these new physics searches, providing also a target experimental sensitivity for them. We analyze $h \to Z X$, $X \to E^{\mathrm{miss}}_T$ searches at the LHC and a future ILC, showing that these exotic Higgs decays can yield sensitivity to unexplored regions of parameter space for ALPs and dark matter models.

Speaker: Jose Miguel No (IFT-UAM/CSIC)

Flasy_2022_JMNo.pdf

15:30 Two component dark matter models: combined particle physics and cosmological approach

We explore the possibility of incorporating particle physics motivated scalar fields to the dark matter cosmological model. We consider two scalar fields, one that does not interact in any way, except via the gravitational interaction, with the rest of the matter in the Universe (which we denote as classical). The second scalar is a BSM field, which can be either a Higgs-like or an axion-like field Then, both the classical and the BSM fields would contribute to the dark matter relic density observed today, and we explore which proportions of each field today are consistent with BBN in the early Universe. We motivate this kind of approach through flavour models where more than one particle candidate to dark matter exists, allowing for a combined cosmological and particle physics approach.

Speaker: Myriam Mondragón

Mondragon_FLASY2022.pdf

16:00 → 16:30 Coffee Break

16:45 → 18:30 Parallel Session I.1

Convener: Mu-Chun Chen

16:45 Leptogenesis assisted by complex scalar singlet

I will discuss our recent work on the contribution to leptogenesis of a complex scalar singlet added to the type-I seesaw extension of the Standard Model. In this scenario, CP is broken spontaneously from the complex vacuum expectation value of the new scalar rather than the complex character of yukawa couplings, allowing to explain leptonic CP violation at the electroweak scale and also contributing to non-zero leptonic CP asymmetries at the leptogenesis scale.

Speaker: Débora Marques Barreiros

Barreiros_FLASY2022.pdf

17:00 Role of Higher-Dimensional Operators in an Anomaly-free U(1) extension

We consider an anomaly-free U(1) extension of the Standard Model with three right-handed neutrinos (RHNs) and two complex scalars, wherein the charge assignments preclude all tree-level mass terms for the neutrinos. Considering this setup, in turn, to be only a low-energy effective theory, we introduce higher-dimensional terms {\em a la} Froggatt-Nielsen to naturally generate tiny neutrino masses. One of the RHNs turns out to be very light, thereby constituting the main decay mode for the $Z'$ and hence relaxing the LHC dilepton resonance search constraints. The lightest RHN has a lifetime comparable to or bigger than the age of the Universe, and, hence, could account for a non-negligible fraction of the dark matter. The two heavy RHNs can lead to resonant leptogenesis provided they are nearly degenerate and their mass splitting is of the order of the decay width.

Speaker: Kuldeep Deka

KuldeepDeka_Flasy22.pdf

17:15 Neutrino mass and the early universe

The long-existing problem of neutrino mass and mixing can be connected to cosmological phenomena, such as the leptogenesis and the existence of dark matter (DM). In the extension of the type I seesaw model with two right-handed (RH) neutrinos, the seesaw Yukawa can drive the DM production, even with the competition from gravitational effect and constraints from leptogenesis. However, the DM production driven by the seesaw Yukawa is not compatible with the testability of the traditional type I seesaw model, which motivates us to seek a variation. By considering two Higgs doublets, a new type Ib seesaw model is proposed, which can explain the neutrino mass, dark matter and leptogenesis simultaneously while keeping its testability. Moreover, the type Ib seesaw model allows a different approach to dark matter production and stability through a $U(1)'$ extension.

Speaker: Bowen Fu

Neutrino.pdf

17:30 Cosmology-friendly time-varying neutrino masses in beta decay experiments

The original sterile neutrino explanation to short baseline anomalies is in strong tension with cosmological observations, because of the copious thermalisation of an extra degrees of freedom. However, we show that this will no longer be an issue in the context of the mass-varying sterile neutrino, for which the sterile neutrino production can be greatly suppressed by the time-varying potential in the early Universe. The time-varying mass is assumed to be generated by the coupling between the sterile neutrino and an ultralight scalar field.

We show how the presence of such mass-varying neutrinos can have relevant implications for terrestrial neutrino experiments. In particular, we study the signatures expected in beta decay experiments, focusing in KATRIN.

Speaker: Pablo Martinez-Mirave (IFIC (CSIC-Univ. Valencia))

PMartinez-Mirave_FLASY2022.pdf

17:45 Neutrino Portal to FIMP Dark Matter with an Early Matter Era

In this talk, I will discuss the freeze-in production of Feebly Interacting Massive Particle (FIMP) dark matter candidates through a neutrino portal, in the case where an early matter-dominated era took place for some period between inflation and Big Bang Nucleosynthesis. In this model, we consider a hidden sector comprised of a fermion and a complex scalar, with the lightest one regarded as a FIMP candidate, and three heavy neutrinos, responsible for mediating the interactions between the Standard Model and the dark matter sectors and for generating the masses of the Standard Model neutrinos. I will present the dynamics of the dark matter candidate throughout the modified cosmic history, evaluate the relevant constraints of the model, and discuss the consequences of the duration of the early matter-dominated era for dark matter production. Finally, I will show that, under some circumstances, this scenario becomes testable through indirect detection searches.

Speaker: Catarina Cosme

Catarina_Cosme_FLASY.pdf

18:00 First direct detection constraints on Planck-scale mass dark matter in DEAP-3600

According to a wide range of astrophysical observations, about one-fourth of all the energy of the universe is due to "dark matter", a non-relativistic and non-luminous kind of matter, different from ordinary “baryonic" matter. While its present abundance is constrained, its mass and the way it interacts with baryonic matter and with itself is still unknown. A confirmed direct detection in a ground-based detector would allow the discovery of dark matter particles, together with the inference of their properties. One of the most promising candidates is the WIMP (Weakly interacting massive particle), thermal relic from primordial universe in the mass range of about (1-10^5) GeV.
In the absence of any confirmed detection in the last two decades, the attention on other dark matter candidates, even up to Planck scale masses, has recently increased, motivating the search in the same experiments. These candidates are expected for instance in Great Unification Theories, as decays of particles out of thermal equilibrium or as dark monopoles. Alternatively, they can result from inflationary gravitational particle production or can be Hawking radiation from primordial black holes. DEAP-3600, with a target of 3.3 tonnes of liquid argon, is the largest running direct detection experiment, set at SNOLAB, in Ontario. Even though it is designed for the WIMP search, it is also sensitive to candidates with masses above 10^{16} GeV and cross-sections in argon above 10^{-24} cm^2. Due to the high cross-sectional area of the detector, the expected signal from these candidates is unique, as it consists of a track of collinear nuclear recoils. Such a change of paradigm motivated the development of a custom analysis of three years of data, looking for multi-scattering dark matter signals. After unblinding, no events were found, leading to world-leading constraints on two composite dark matter models, with masses up to the Planck-scale one.

Speaker: Michela Lai (Cagliati State University)

Michela_Lai_FLASY2022.pdf

16:45 → 18:30 Parallel Session II.1

Convener: Monika Blanke

16:45 Long-lived particles and meson decays in $N_R$LEFT

Electroweak scale neutrino mass models predict the existence of heavy neutral leptons (HNLs) at an energy range that could be within reach of collider experiments. In particular, GeV scale HNLs could be produced in heavy meson decays at the LHC. In this scenario, the relevant theory to study HNL phenomenology is the low-energy effective field theory extended with right-handed neutrinos, $N_R$, denoted by $N_R$LEFT. We are especially interested in the regime where the HNLs produced from meson decays are long-lived and can potentially decay within proposed future (far) detectors at the LHC. We determine the expected sensitivities of these far detectors to HNLs for $N_R$LEFT four-fermion operators containing $N_R$ and a pair of quarks.

Speaker: Rebeca Beltran (IFIC (CSIC-UV))

HNL_RB_FLASYv2.pdf

17:00 Multiboson signals in the UN2HDM

Cascade decays of new particles like a heavy Z’ gauge boson might produce distinctive experimental signatures that are still uncovered by new physics searches at the Large Hadron Collider. We introduce in this work the UN2HDM, which enlarges the gauge symmetry of the Next-to-two-Higgs doublet model (N2HDM), a Standard Model extension with two complex Higgs doublets and one complex Higgs singlet, with an extra U(1) group. For regions of UN2HDM’s parameter space allowed by theoretical and experimental constraints, we show that multiboson signals with sizeable branching ratios may arise, as a result of cascade decays of heavy Z’ bosons. These results motivate the development of new physics searches that cover multiboson signals, in particular those observed in the context of the UN2HDM.

Speaker: João Seabra

UN2HDM_FLASY.pptx

17:15 Collider phenomenology of neutral scalars in a flavoured muti-Higgs model

In this presentation, I shall discuss on collider signatures with a focus on new physics scenarios that are predicted in various classes of multi-Higgs doublet models, with a focus on a recently proposed BGL-like model, enhanced with an abelian U(1) flavour symmetry. A thorough analysis of one of these signatures is conducted in the context of the Large Hadron collider, based on a topology with two charged leptons and 4 jets arising from first/second generation chiral quarks. I discuss how the kinematics of the scalar fields can be used to efficiently separate the signal from the dominant backgrounds and its implications in future runs of the LHC.

Speaker: João Pedro Pino Gonçalves (University of Aveiro)

JoaoPino_FLASY.pdf

17:30 Exploring multi-Higgs models with softly broken large discrete symmetry groups

We develop methods to study the scalar sector of multi-Higgs models with large discrete symmetry groups that are softly broken. While in the exact symmetry limit, the model has very few parameters and can be studied analytically, proliferation of quadratic couplings in the most general softly broken case makes the analysis cumbersome. We identify two sets of soft breaking terms which play different roles: those which preserve the symmetric vacuum expectation value alignment, and the remaining terms which shift it. Focusing on alignment preserving terms, we check which structural features of the symmetric parent model are conserved and which are modified. We find remarkable examples of structural features which are inherited from the parent symmetric model and which persist even when no exact symmetry is left. The general procedure is illustrated with the example of the three-Higgs-doublet model with the softly broken symmetry group $\Sigma(36)$.

Speaker: Miguel Levy (CFTP/IST)

Levy.pdf

17:45 A flavor model for cobimaximal mixing

The lepton mixing ansatz, known as cobimaximal mixing, still remains an allowed mixing scheme for leptons which predicts a maximal value for the atmospheric mixing angle ($\theta_{23}=45^{\circ}$) and the Dirac CP phase is fixed at $\delta=\pm 90^{\circ}$. Here we analyze a minimal model to understand the cobimaximal lepton mixing based on $A_4$ non-Abelian discrete flavor symmetry. Tiny neutrino mass and mixing is obtained by relying on such a flavor symmetric type-I seesaw mechanism. Subsequently, we study the associated phenomenology and predict the absolute neutrino mass and effective neutrino mass parameter responsible for neutrinoless double-beta decay. We further comment on the lepton asymmetry of the universe in this context.

Speaker: Biswajit Karmakar

biswajit-flasy-2022.pdf

18:00 Hunting for Discrete Goldstone Bosons

Pseudo Goldstone Bosons (pGBs) arising from the spontaneous breaking of an exact discrete symmetry have non-zero scalar masses which are immune to quadratic corrections. This is at variance with non-linearly realized continuous symmetries, for which the masses of pGBs require an explicit breaking mechanism and enjoy no such protection. The resulting symmetry-protected masses and potentials offer promising physics avenues, both theoretically and in view of the blooming experimental search for ALPs and other BSM particles. We develop this theoretical setup using invariant theory and focusing on the so-called natural minima of the potential, which are independent of the specific ultraviolet completion of the theory. Typically, a subgroup of the discrete symmetry —which is otherwise non-linearly realized— remains explicit in the spectrum, i.e. realized “à la Wigner”. This suggests tell-tale experimental signals: at least two degenerate scalars produced simultaneously, plus specific ratios of multi-scalar amplitudes. The examples of A4 and A5 as subgroups of SO(3) are explored in substantial detail and other cases of phenomenological interest are discussed.

Speaker: Víctor Enguita-Vileta (Universidad Autónoma de Madrid)

Enguita FLASY22.pdf

18:15 Heavy neutrino-antineutrino oscillations at the HL-LHC

The Standard Model lacks an explanation for the observed light neutrino oscillation data. This can be alleviated by adding at least two right-handed Majorana fermions in order to generate neutrino masses via the seesaw mechanism. These right-handed Majorana fermions can be light enough to be collider accessible as long as they are nearly mass degenerate. These pseudo-Dirac heavy neutral leptons exhibit a unique phenomenology. The most striking feature is the appearance of neutrino antineutrino oscillations. We demonstrate that it is in principle possible to measure the heavy neutrino oscillation length at the HL-LHC.

Speaker: Jan Hajer (Universidade de Lisboa)

Heavy neutrino-antineutrino oscillations at the HL-LHC

16:45 → 18:30 Parallel Session III.1

Convener: Luca Merlo

16:45 The Cost of an ALP Solution to the Neutral B-Anomalies

Speaker: Jesús Bonilla

The Cost of an ALP Solution to the_Full.pdf

17:00 Nonresonant Searches for Axion-Like Particles in Vector Boson Scattering Processes at the LHC

We propose a new search for Axion-Like Particles (ALPs), targeting Vector Boson Scattering (VBS) processes at the LHC. We consider nonresonant ALP-mediated VBS, where the ALP participates as an off-shell mediator. This process occurs whenever the ALP is too light to be produced resonantly, and it takes advantage of the derivative nature of ALP interactions with the electroweak Standard Model bosons. We study the production of $ZZ$, $Z\gamma$, $W^{\pm}\gamma$, $W^{\pm}Z$ and $W^{\pm}W^{\pm}$ pairs with large diboson invariant masses in association with two jets. Working in a gauge-invariant framework, upper limits on ALP couplings to electroweak bosons are obtained from a reinterpretation of Run 2 public CMS VBS analyses. The constraints inferred on ALP couplings to $ZZ$, $Z\gamma$ and $W^{\pm}W^{\pm}$ pairs are very competitive for ALP masses up to 100 GeV. They have the advantage of being independent of the ALP coupling to gluons and of the ALP decay width. Simple projections for LHC Run 3 and HL-LHC are also calculated, demonstrating the power of future dedicated analyses at ATLAS and CMS.

Speaker: Jonathan Machado-Rodríguez (Instituto de Física Teórica - UAM)

jmachado-FLASY-v2.pdf

17:15 Effects of squared four-fermion operators of the Standard Model Effective Field Theory on meson mixing

The Standard Model Effective Field Theory (SMEFT) is a universal way of parametrizing New Physics (NP) manifesting as new, heavy particle interactions with the Standard Model (SM) degrees of freedom, that respect the SM gauged symmetries. Higher order terms in the NP interactions possibly lead to sizable effects, mandatory for meaningful phenomenological studies, such as contributions to neutral meson mixing, which typically pushes the scale of NP to energy scales much beyond the reach of direct searches in colliders. I discuss the leading-order renormalization of double-insertions of dimension-6 four-fermion operators that change quark flavor by one unit (i.e., $ | \Delta F | = 1 $, $ F = $ strange-, charm-, or bottom-flavor) by dimension-8 operators relevant to meson mixing (i.e., $ | \Delta F | = 2 $) in SMEFT, and consider the phenomenological implications of contributions proportional to large Yukawas, setting then bounds on the Wilson coefficients of operators of dimension-6. Given the underlying interest of SMEFT to encode full-fledged models at low energies, this work stresses the need to consider dimension-8 operators in phenomenological applications of dimension-6 operators of SMEFT.

Speaker: Luiz Vale Silva

Vale_Silva_2.pdf

17:30 Addressing the CKM unitarity problem with a vector-like up quark

We point out that hints of deviations from unitarity in the first row of the CKM matrix may be explained by the presence of a single vector-like top. We study how the stringent experimental constraints arising from CP Violation in the kaon sector and from meson mixing can be satisfied in the proposed framework. In order for the deviations from unitarity to be of the required size while keeping the theory perturbative, the new top quark should have a mass below 7 TeV, which could be probed in upcoming experiments at the energy frontier.

Speaker: Pedro M. F. Pereira (Instituto Superior Tecnico)

FLASY_PedroMFPereira.pdf

17:45 CP violation in hadronic two-body D meson decays: A global fit under the SM hypothesis

In 2019 the LHCb experiment discovered for the first time a clear signal of direct CP violation in the charm meson decays to $\pi^+\pi^-$ and $K^+K^-$, a result which is expected to be further refined in the upcoming decade. However, the theoretical SM determination of the strong part of those amplitudes remains incomplete up to date. In this work, we make use of dispersion relations to properly treat final-state interactions in the 2-channel case, with the strong mixing matrix being extracted from data on pion and kaon rescattering. The results of our method are then inputted into a global fit to current experimental data on branching fractions and CP asymmetries in order to extract the magnitude of penguin diagrams.

Speaker: Eleftheria Solomonidi (IFIC (CSIC-Univ. of Valencia))

SolomonidiFLASY.pdf

18:00 Stabilizing the SM with Vector-like Fermions

We address the notorious (meta-)stability issue of the standard model and pose it as a model building question: What does it take, in a minimally invasive way, to extend the standard model into a model that has neither poles nor instabilities up to the Planck scale?
We point out new ways to achieve this using vector-like fermions, which correspond to BSM quarks or leptons. We identify viable ranges of BSM parameters such as fermion multiplicities, masses and Yukawa interactions, which give rise to stable and predictive RG trajectories up to the Planckian regime. The vector-like fermions can be in the TeV-range, and searched for at the LHC. For a nontrivial flavor structure of the BSM sector severe constraints arise from tree-level FCNC's yielding lower mass bounds of up to several hundred TeV.

Speaker: Tim Höhne

Höhne.pdf

18:15 Yukawa ratios and nucleon decay fingerprints in SU(5) GUTs

We investigate the predictions for various nucleon decay rates in non-supersymmetric SU(5) models, where the masses of the third and second family down-type quarks and charged leptons each stem dominantly from single GUT operators and present a ``fingerprinting'' method to distinguish between GUT models with different flavor structure with the use of future experimental results.

Speaker: Kevin Hinze

Presentation_FLASY_2022.pdf

Wednesday, 29 June

09:00 → 10:30 Morning Session

Convener: Gustavo Burdman

09:00 On gauge and matter unification in composite Higgs models

The gauge and matter structure of the SM hint at gauge and matter unification not far below the Planck scale. Preserving this in composite Higgs imposes restrictions on the embedding of the SM symmetry, and the standard composite-Higgs custodial symmetries, into the strong-sector symmetry group. I describe a minimal setup which, remarkably, automatically includes a vector leptoquark of the kind suggested by the flavour anomalies, and can be phenomenologically viable in the face of collider, electroweak and cosmological constraints. I will briefly remark on flavour, which as usual is more model-dependent.

Speaker: Sebastian Jaeger

jaeger-flasy2022.pdf

09:30 Scotogenic A_5 to A_4 Dirac Neutrinos

Radiative Dirac neutrino masses and their mixing are linked to dark matter through the non-Abelian discrete symmetry A_5 of the 4-dimensional pentatope, softly broken to A_4 of the 3-dimensional tetrahedron. Dark neutral fermions are produced through Higgs decay.

Speaker: Ernest Ma

Ma_FLASY2022.pdf

10:00 Flavour anomalies meet flavour symmetry

We propose an extension of the Standard Model with a leptoquark and a flavour symmetry that is the direct product of a dihedral and a cyclic group. We show that both the flavour anomalies in $R(D)$ and $R(D^\star)$ and of the anomalous magnetic moment of the muon as well as the charged fermion mass hierarchy and the quark mixing pattern can be explained. At the same time, constraints imposed from e.g. the non-observation of charged lepton flavour violating processes can be passed in this model for masses of the leptoquark as small as 2 TeV. The flavour structure of the couplings between the leptoquark and the Standard Model fermions is determined by a residual group of the flavour symmetry. Only four spurions, acquiring different vacuum expectation values, are necessary in order to achieve the desired form of the leptoquark couplings and of the charged fermion mass matrices. We study the phenomenology of this model with analytic estimates as well as perform numerical scans of its parameter space.

Speaker: Claudia Hagedorn

Hagedorn_FLASY2022.pdf

10:30 → 11:00 Coffee Break

11:00 → 12:30 Morning Session

Convener: Myriam Mondragón

11:00 Neutrino transition in dark matter

An ultralight dark matter may have interesting implications in neutrino physics which have been studied actively in recent years. There can occur yet unexplored medium effect of neutrino transition which must be taken into account when describing the oscillations of neutrinos propagating through dark matter. Strong constraints on the model parameters are obtained considering the solar neutrino oscillation.

Speaker: Eung Jin Chun

EJChun-FLASY2022.pdf

11:30 Multi-component dark sectors: symmetries, asymmetries and conversions

Dark matter may be part of a complex dark sector, possibly involving several stable components. It may also comprise both symmetric and asymmetric components. In this talk, I will present the framework needed to compute the relic abundance in these extended dark sectors, discuss the role of dark matter conversions, and show some recent results.

Speaker: Juan Herrero Garcia (IFIC, UV/CSIC)

talk_Lisbon.pdf

12:00 Neutrino phenomenology in the presence of light gauge bosons

Neutrino masses and the existence of non-baryonic Dark Matter (DM) are, together with the Baryon asymmetry in the Universe, three pieces of evidence that the Standard Model is not the final theory of particle physics. In this talk, we will discuss scenarios with a gauged U(1)´ symmetry in the light of current and future coherent elastic neutrino-nucleus scattering experiments. We will also discuss how the generation of neutrino masses can be linked to the DM sector.

Speaker: Eduardo Peinado

Peinado-Flasy2022.pdf

12:30 → 12:40 Group Photo: Group photo

12:40 → 14:40 Lunch Break

17:10 → 19:30 Boat Trip

20:00 → 22:00 Dinner

Thursday, 30 June

09:00 → 10:30 Morning Session

Convener: Stefan Antusch

09:00 Neutrino and Flavour Models, from the Planck Scale to the Electroweak Scale

We discuss various approaches to the flavour problem of the Standard Model, including the LFU violation anomalies in B decays, in which the Yukawa couplings may be determined by symmetry or anarchy and may be renormalizable or effective. If the Yukawa couplings are effective, in principle the flavour scale can be anywhere from the Planck scale to the Electroweak scale, where SUSY/GUTs suggest a high scale theory, while LFU anomalies in B decays require a low flavour scale. In the symmetry approach, large neutrino mixing suggests the use of non-Abelian symmetry, possibly due to a finite modular symmetry, and we such discuss examples of this. We also discuss an anarchical example of fermion masses based on the Twin Pati-Salam gauge group, where the effective low scale Yukawa couplings arise from exchange of fourth family vector-like fermions, which also mediate the couplings to TeV scale vector leptoquarks which could be responsible for the LFU violation anomalies.

Speaker: Steve King

09:30 Quantum-Gravitational Decoherence and the Number of Flavors in the Universe

We discuss the interplay of wave packet decoherence and decoherence induced by quantum gravity via interactions with spacetime foam for high energy astrophysical neutrinos. In this context we point out a compelling consequence of the expectation that quantum gravity should break global symmetries, namely that quantum-gravity induced decoherence may not only be the most sensitive probe for quantum properties of spacetime, but also can provide both a powerful tool for the search for new particles, including totally decoupled backgrounds interacting only gravitationally, and at the same time a window into the intricacies of black hole information processing.

Speaker: Heinrich Päs (TU Dortmund)

QG-Deco-FLASY.pdf

10:00 Completing the Standard Model

In this talk I will describe symmetry-based approaches to some of the main drawbacks of the standard model.

Speaker: Jose W.F. Valle

flasy-2022-valle.pdf

10:30 → 11:00 Coffee Break

11:00 → 12:30 Morning Session

Convener: Ernest Ma

11:00 Progress in baryogenesis via neutrino oscillations

Low energy baryogenesis via sterile neutrino oscillations has received recently considerable attention, since it can be testable in future experiments such as SHIP and FCC. Focusing on the minimal model with just two heavy sterile neutrinos, we have studied bounds on the mixing among them and the active ones from successful baryogenesis, both through a numerical scan and by deriving analytic approximations. We also draw some conclusions about the flavour structure of the neutrino Yukawa couplings, depending on the mass degeneracy of the heavy states.

Speaker: Nuria Rius

Rius_FLASY2022.pdf

11:30 VISHnu: flavour-variant DFSZ axion model for inflation, neutrino masses, dark matter and baryogenesis

The nuDFSZ model identifies the Peccei-Quinn scale with the type-I seesaw scale, so accommodates neutrino mass generation and baryogenesis via leptogenesis. It also features axion dark matter, and of course solves the strong-CP problem. In this talk I will introduce VISHnu, a modification of nuDFSZ that uses flavour-dependent Higgs Yukawa couplings to (i) remove the usual DFSZ cosmological domain wall problem, and (ii) add inflationary dynamics, thereby progressing the scenario towards having a complete and successful cosmological history.

Speaker: Raymond Volkas

Volkas-FLASY-2022.pdf

12:00 Unconventional axions and ALPs

Axions which solve the strong CP problem but can be much heavier or much lighter than the canonical QCD axion will be discussed, as well as recent theoretical developments protecting ALPs from ultraviolet sensitivity and resulting in degenerate ALPs.

Speaker: Belen Gavela

Gavela-Flasy-2022-Lisbon.pdf

12:30 → 14:30 Lunch Break

14:30 → 16:00 Afternoon Session

Convener: Svjetlana Fajfer

14:30 Beyond Jarlskog: Playing with Flavor Invariants

The talk will be about CP violation but also about axion shift-invariance breaking. In both cases, Jarlskog-like flavour invariants capture collective breaking effects and allow one to define parameters orders that measure the amount of symmetry breaking and that could be used to define a self-consistent power counting closed under the renormalisation group evolution.

Speaker: Christophe Grojean (DESY (Hamburg) and Humboldt University (Berlin))

Grojean_FLASY (1).pdf

15:00 New Physics in Yukawa Couplings with Flavour Symmetries

Colliders and flavour facilities provide complementary information on fermion-Higgs couplings. Within the SMEFT approach, bounds on the new physics scale affecting the Yukawa couplings are obtained assuming the presence of a flavour symmetry. Limits on the diagonal couplings arise from Higgs boson production and decays at the LHC experiments, while bounds on non-diagonal couplings from a variety of FCNC and radiative decay processes. With the present precision of the LHC data, the FCNC data give stronger bounds on the scale of new physics than the collider data (obviously, for the MFV ansatz only collider data are relevant), obtaining bounds in the TeV range. In case of CP violating sources, electron EDM provides the strongest limits.

Speaker: Luca Merlo (Universidad Autonoma de Madrid)

Merlo, FLASY.pdf

15:30 Flavour symmetries in the SMEFT

The talk will discuss the role of flavor symmetries in defining the structure of the Standard Model Effective Field Theory and it will give an overview of their implications for searches of indirect new physics signals at the LHC.

Speaker: Ilaria Brivio (University of Heidelberg)

slides_Flasy2022.pdf

16:00 → 16:30 Coffee Break

16:45 → 18:30 Parallel Session I.2

Convener: Andreas Trautner

16:45 An ultraviolet completion for the Scotogenic model

The Scotogenic model is an economical scenario that generates neutrino masses at the 1-loop level and includes a dark matter candidate. This is achieved by means of an ad-hoc $Z_2$ symmetry, which forbids the tree-level generation of neutrino masses and stabilizes the lightest $Z_2$-odd state. Neutrino masses are also suppressed by a quartic coupling, usually denoted by $\lambda_5$. While the smallness of this parameter is natural, it is not explained in the context of the Scotogenic model. We construct an ultraviolet completion of the Scotogenic model that provides a natural explanation for the smallness of the $\lambda_5$ parameter and induces the $Z_2$ parity as the low-energy remnant of a global $U(1)$ symmetry at high energies. The low-energy spectrum contains, besides the usual Scotogenic states, a massive scalar and a massless Goldstone boson, hence leading to novel phenomenological predictions in flavor observables, dark matter physics and colliders.

Speaker: Pablo Escribano

FLASY2022_Escribano.pdf

17:00 Scotogenic Majorana neutrino masses in an orbifold theory of flavor

An extra-dimensional extension of the standard model is presented. It displays a flavor $A_4$ symmetry among the three generations of fermions at the high energy regime. The model offers a symmetrical origin to quark and lepton mixings in a unified framework. The neutrino masses in the model emerge at one loop in a scotogenic fashion. The minimalist set up of the model is highly predictive and includes a dark sector whose lightest particle can be identified as a dark matter candidate.

Speaker: Omar Medina (Instituto de Física Corpuscular (CSIC - Universitat de València))

Flasy2022-OmarMedina.pdf

17:15 Flavored Dark Matter: Scotogenic Dark Symmetry from Flavor symmetry

It is well known in the literature that the "Scotogenic" model explains dark-matter (DM) along with neutrino mass generation in a very simple and elegant way. However, it needs an 'ad-hoc' $Z_2$ symmetry to explain DM and also does not shed any light on the neutrino flavor sector, for which typically another "flavor symmetry" needs to be added to the model. Furthermore, neither the dark symmetry nor the flavor symmetry shed any light on the existence of two different mass square scales in neutrino oscillation data. In this talk, we will show how the scotogenic dark symmetry and scoto-seesaw mass mechanism can naturally arise from the $A_4$ flavor symmetry. It will be discussed that the breaking of the flavor $A_4$ symmetry to its $Z_2$ sub-group automatically leads to a hybrid mass mechanism where neutrinos get mass from a combination of seesaw and loop mechanism. In addition, the unbroken $Z_2$ sub-group plays the role of the scotogenic dark symmetry. We will show that the model successfully explains the dark matter phenomenology. Finally, we will analyze the potential of testing the model for neutrino oscillations as well as at $0\nu\beta\beta$ decay experiments.

Speaker: Newton Nath (INFN Bari)

NN-FLASY22.pdf

17:30 Flavour and dark matter in a hybrid seesaw/scotogenic model

I will present our recent work based on a hybrid Type-II seesaw/scotogenic model supplemented with a discrete flavour symmetry where CP is broken by the vacuum. Namely, we analyse compatibility with low-energy neutrino observables, study the charged lepton flavour violation implications and review the scalar and fermionic dark matter prospects of our framework.

Speaker: Henrique Brito Câmara

HBCâmara_FLASY_2022.pdf

17:45 Sterile neutrino portals to Majorana dark matter

Stringent constraints on the interactions of dark matter with the Standard Model suggest that dark matter does not take part in gauge interactions. In this regard, the possibility of communicating between the visible and dark sectors via gauge singlets seems rather natural. We consider a framework where the dark matter talks to the Standard Model through its coupling to sterile neutrinos, which generate active neutrino masses. We focus on the case of Majorana dark matter, with its relic abundance set by thermal freeze-out through annihilations into sterile neutrinos. We use an effective field theory approach to study the possible sterile neutrino portals to dark matter. We find that both lepton-number-conserving and lepton-number-violating operators are possible, yielding an interesting connection with the Dirac/Majorana character of active neutrinos. In a second step, we open the different operators and outline the possible renormalisable models. We analyse the phenomenology of the most promising ones, including a particular case in which the Majorana mass of the sterile neutrinos is generated radiatively.

Speaker: Arsenii Titov (University of Valencia and IFIC)

NDM_portals_FLASY_2022_Titov.pdf

18:00 Tasting Flavoured Majorana Dark Matter

I will discuss a flavoured dark matter (DM) model set up in the so called Dark Minimal Flavour Violation (DMFV) framework. The model extends the Standard Model by a DM flavour triplet and a scalar mediator, through which the new dark fermions couple to right-handed up-type quarks. This interaction is governed by a new coupling matrix which is assumed to constitute the only new source of flavour and CP violation. After briefly presenting the details of this simplified model and the DMFV framework in the first part, I will continue and discuss its phenomenology in the context of collider, flavour, cosmology and direct detection constraints. I will further ‚taste‘ the flavour of the DM field by discussing which DM flavour is preferred after a combined analysis of all experimental constraints mentioned above. In the last part, I will present an estimation of the direct CP asymmetry in charm decays in this model and conclude my talk by discussing if it is capable of explaining the large measured value of this asymmetry.

Speaker: Harun Acaroglu (Karlsruhe Institute of Technology)

Acaroglu_Flasy2022.pdf

18:15 Dark matter in three-Higgs-doublet models with S$_{3}$ symmetry

Models with two or more scalar doublets with discrete or global symmetries can have vacua with vanishing vacuum expectation values in the bases where symmetries are imposed. If a suitable symmetry stabilises such vacua, these models may lead to interesting dark matter (DM) candidates, provided that the symmetry prevents couplings among the DM candidates and the fermions. We analyse three-Higgs-doublet models with an underlying S$_3$ symmetry. These models have many distinct vacua with one or two vanishing vacuum expectation values (1) which can be stabilised by a remnant of the S$_3$ symmetry which survived spontaneous symmetry breaking. In our framework the stability of the DM sector results from a $\mathbb{Z}_2$ symmetry. We identify all possible DM models based on vacua in the context of S$_3$-symmetric three-Higgs-doublet models, allowing also for softly broken S$_3$ scalar potential.

We focus on two specific models R-II-1a (2) and C-III-a. In these cases one of the scalar doublets provides the DM sector, while the other two are active. The way the fermions couple to the scalar sector is constrained by the S$_3$ symmetry and is such that the flavour structure of the model is solely governed by the $V_\mathrm{CKM}$ matrix which, in our framework, is not constrained by the S$_3$ symmetry. The main difference between the models is that there is no CP violation in R-II-1a, while in C-III-a there is an irremovable phase present. We explore models numerically, based on theoretical and experimental constraints. After applying a number of successive checks over the parameter space we found a viable DM mass region to be [52.5, 89] GeV for R-II-1a and [6.5, 44.5] GeV for C-III-a.

Speaker: Anton Kuncinas (CFTP/IST, U. Lisboa)

7 Kuncinas.pdf

16:45 → 18:30 Parallel Session II.2

Convener: Michael Ratz

16:45 The hidden side of scalar-triplet models with spontaneous CP violation

The Standard Model of particle physics is in remarkable agreement with most experimental data so far. However, a lot of questions remain unanswered, such as the origin of neutrino masses or the need for extra sources of CP violation. Possible solutions rest on scalar sector extensions, popular beyond-the-Standard-Model scenarios. The addition of scalar triplets is an attractive possibility, with small neutrino masses being generated via the type-II seesaw mechanism. Such models are much studied in the literature, but they still hide some features underneath. Although not possible with just one triplet, a CP-breaking vacuum is possible with the addition of two triplets, which could lead to interesting leptonic CP-violating effects. However, it also introduces novel and unexpected features in its scalar spectrum. In this work, we briefly present such hidden features. Based on https://arxiv.org/pdf/2109.13179.pdf.

Speaker: Bernardo Lopes Gonçalves

Talk_FLASY22.pdf

17:00 Phenomenology of a flavoured multiscalar BGL-like model with three generations of massive neutrinos

In this talk, I will present several possible anomaly-free implementations of the Branco-Grimus-Lavoura (BGL) model with two Higgs doublets and one singlet scalar. The model also includes three generations of massive neutrinos that get their mass via a type-I seesaw mechanism. A particular anomaly-free realization, which we dub νBGL-1 scenario, is subjected to an extensive phenomenological analysis, from the perspective of electroweak precision, Higgs and flavour observables

Speaker: Vasileios Vatellis

Vasileios_FLASY2022.pdf

17:15 Neutrino mass and flavor anomalies

Experimental hints for lepton flavor universality violation in beauty-quark decay both in neutral- and charged-current transitions require an extension of the Standard Model for which scalar leptoquarks (LQs) are the prime candidates. Besides, these same LQs can resolve the long-standing tension in the muon and the recently reported deviation in the electron $g-2$ anomalies. These tantalizing flavor anomalies have discrepancies in the range of $2.5\sigma-4.2\sigma$, indicating that the Standard Model of particle physics may finally be cracking. In this talk, we propose a resolution to all these anomalies within a unified framework that sheds light on the origin of neutrino mass. In this model, the LQs that address flavor anomalies run through the loops and generate neutrino mass at the two-loop order while satisfying all constraints from collider searches, including those from flavor physics.

Speaker: shaikh saad (University of Basel)

Saad_FLASY2022.pdf

17:30 Lepton masses from a flavorful Peccei-Quinn-Froggat Nielsen U(1) symmetry

We consider a model where a global U(1) symmetry is simultaneously responsible for solving the Strong CP problem à la Peccei-Quinn and for explaining the lepton mass hierarchies à la Froggatt-Nielsen. The axion resulting from the symmetry breaking can have sizeable flavor violating couplings, which propagate to the SM 126 GeV Higgs through scalar mixing. We investigate the bounds from Higgs flavor violating decays in the LHC, as well as projections for HL-LHC and ILC/CLIC.

Speaker: Leon Manuel Garcia de la Vega

LeonM_FLASY2022.pdf

17:45 Absolute neutrino mass scale and dark matter stability from flavour symmetry

We explore a simple but extremely predictive extension of the scotogenic model. We promote the scotogenic symmetry $\mathbb{Z}_2$ to the flavour non-Abelian symmetry $\Sigma(81)$, which can also automatically protect dark matter stability. In addition, $\Sigma(81)$ leads to striking predictions in the lepton sector: only Inverted Ordering is realised, the absolute neutrino mass scale is predicted to be $m_\text{lightest} \approx 7.5 \times 10^{-4}$ eV and the Majorana phases are correlated in such a way that $|m_{ee}| \approx 0.018$ eV. The model also leads to a strong correlation between the solar mixing angle $\theta_{12}$ and $\delta_{CP}$, which may be falsified by the next generation of neutrino oscillation experiments. The setup is minimal in the sense that no additional symmetries or flavons are required.

Speaker: Salvador Centelles Chuliá (MPIK (Heidelberg))

talk-centelles.pdf

18:00 Automatic Nelson-Barr from Gauged Flavor

Despite exceptional appeal of the Peccei-Quinn mechanism, alternative solutions
to the strong CP problem should be pursued. In this direction and given the tight
connection of the strong CP problem with flavor, we explore how a Nelson-
Barr mechanism (NB) arises automatically in the context of gauged flavor models and solves some of the issues of usual NB realizations.

Speaker: Pablo Quilez Lasanta (Deutsches Elektronen-Synchrotron (DE))

Automatic NB from gauged flavor.pdf

16:45 → 18:30 Parallel Session III.2

Convener: Valentina De Romeri

16:45 Decoherence and Neutrino Oscillations: from Microscopic to Macroscopic

We present a generic structure (the layer structure) for decoherence effects in neutrino oscillations by combining the concept of the open quantum system and quantum field theory, which includes and parameterize decoherence effects from quantum mechanical and classical uncertainties. With the help of the layer structure, we classify the former as state decoherence (SD) and the latter phase decoherence (PD), then further conclude that both SD and PD result from phase wash-out effects of different phase structures on different layers. Such effects admit for simple numerical calculations of decoherence for a given width and shape of uncertainties. While our structure is generic, so are the uncertainties, nonetheless, a few notable ones are: the wavepacket size of the external particles, the effective interaction volume at production and detection, the energy reconstruction model and the neutrino production profile. Furthermore, we estimate the experimental sensitivities for SD and PD, parameterized by the uncertainty parameters, for reactor neutrinos and decay-at-rest neutrinos, using a traditional rate measuring method and a novel
phase measuring method.

Speaker: Ting Cheng

FLASY_Cheng.pdf

17:00 Exploring BSM models at Long Baseline neutrino experiments

Standard three-neutrino oscillations are a well known phenomenon; however, the uncertainties on the mixing parameters do not allow us to exclude the possibility of the presence of new physics effects in the lepton sector. Future long-baseline (LBL) accelerator experiments may be able to probe different BSM models in neutrino oscillations. Indeed, these experiments should be able to look at different oscillation channels and to search for new physics phenomena at both short (near detectors) and long (far detectors) distances.
We studied the performances of two of the most promising experiments, namely DUNE and T2HKK in constraining different models.

For instance, we considered the effects of the possible Non-Unitarity of the mixing matrix at the detectors of such experiments. Moreover, we show how the precision on the $\delta_{CP}$ measurements could be affected if any deviation from unitarity of the PMSN matrix is present.

Furthermore, we explored the capabilities of the DUNE experiment in measuring scalar and vector Non Standard Interaction (NSI) parameters, taking into account different benchmark scenarios.

Speaker: Alessio Giarnetti (Roma Tre University & INFN)

Giarnetti_FLASY.pdf

17:15 A novel window into Dirac vs. Majorana nature of neutrinos using CE$\nu$NS experiments

In the presence of transition magnetic moments between active and sterile neutrinos, the search for a Primakoff upscattering process at Coherent Elastic Neutrino Nucleus Scattering (CE$\nu$NS) experiments provide very stringent constraints on the neutrino magnetic moment. I will discuss how a radiative upscattering process with a photon emitted in the final state can provide a novel experimental mode to probe neutrino transition magnetic moments beyond existing limits and how the differential distributions for such a radiative mode can also be sensitive to the Dirac vs. Majorana nature of neutrinos.

Speaker: Chandan Hati

CH_FLASY22_pdf.pdf

17:30 Correlating Muon g−2 Anomaly with Neutrino Magnetic Moments

We show that the models that induce neutrino magnetic moments while maintaining their small masses naturally also predict observable shifts in the muon anomalous magnetic moment. This shift is of the right magnitude to be consistent with the Brookhaven measurement as well as the recent Fermilab measurement of the muon g−2. This is pointing out the direct correlation between the magnetic moment of SM charged lepton and neutral lepton (neutrino) by showing that the measurement of muon g−2 by the Fermilab experiment can be an in-direct and novel test of the neutrino magnetic-moment hypothesis, which can be as sensitive as other ongoing-neutrino/dark matter experiments. Such a correlation between muon g−2 and the neutrino magnetic moment is generic in models employing leptonic family symmetry to explain a naturally large neutrino magnetic moment. This talk will be based on results obtained with K.S. Babu, Manfred Lindner, and Vishnu P.K. and presented in hep-ph 2007.04291 and 2104.03291.

Speaker: Dr Sudip Jana (Max-Planck-Institut für Kernphysik)

FLASY22.pdf

17:45 Indirect search for sub-GeV dark matter with neutrino telescopes

We discuss indirect searches for sub-GeV dark matter (DM) that annihilates directly to a neutrino pair or a pair of new bosons subsequently decaying to neutrinos. The neutrino spectrum from the DM annihilation is monochromatic in the former process and a polynomial shape in the latter case. As a benchmark scenario, we consider a gauged U(1)$_{L_\mu-L_\tau}$ model under which a DM field is charged, and evaluate the sensitivity at Super-Kamiokande and future Hyper-Kamiokande experiments. We also discuss the interplay between the muon g-2 anomaly and DM physics.

Speaker: Shohei Okawa (ICCUB)

FLASY_Okawa.pdf

18:00 A new software to compute MSSM squared amplitudes for particle physics and relic density calculations

The increasing need of numerical predictions for dark matter models is not always easy to satisfy looking at the software available today. With this work, we present a code to compute 2 to 2 squared scattering amplitudes using MARTY, with all the benefits of having a fully open source C++ code to handle. The numerical library generated in this way has been enriched with additional features, aiming at allowing the user to easily include and use such a library in external softwares. We restricted ourselves to the tree-level amplitudes in the MSSM relevant to solve the Boltzmann equation in a freeze-out scenario. Future development of this work will provide a direct interface with SuperIso Relic and the possibility to choose more general models.

Speaker: Marco PALMIOTTO (Institut de physique des deux infinis Lyon, Université Claude Bernard Lyon 1)

presentation_flasy.pdf

18:15 An Event Generator For New Physics in $B \to D^* \ell \nu$ decay

In this talk I am going to present our newly developed event generator tool based on EvtGen that allows us to simulate new physics (NP) signatures in charged current semileptonic $\bar{B}\to D^{*+} \ell^- \bar{\nu}_\ell$ decays. Recent experimental results from Belle, Babar and LHCb have all pointed towards new physics in the weak $b\to c$ transitions which urge for an immediate need of advanced analysis techniques which we achieve through this simulator. We have used our Monte Carlo (MC) tool to study in detail the semileptonic decay with muon and electron in the final state. Throughout our analysis we have assumed that the electron mode decay is well described by the SM. We have examined the signatures of new physics in the muon mode which are consistent with current data. Angular asymmetries such as $A_{FB}$, $𝑆_3$, $S_5$ and $S_7$, that can be extracted from the fully reconstructed angular distribution, are found to be highly sensitive to the presence of NP. In order to reduce the dependence on form factor uncertainties, we introduce $\Delta$-observables for the angular asymmetries by taking the difference between the observables for the muon and electron final states. Apart from analyzing the $\Delta$ observables for three distinct NP scenarios, we have additionally exhibited the prospects of probing such NP couplings with the future 50 ab$^{−1}$ of Belle II data.

Speaker: Lopamudra Mukherjee (University of Mississippi)

FLASY22_Lopa.pdf

Friday, 1 July

08:55 → 10:30 Morning Session

Convener: Morimitsu Tanimoto

09:00 Flavour seesaw and phenomenological consequences

Speaker: Manfred Lindner (Max-Planck-Institut fuer Kernphysik, Heidelberg, Germany)

Lindner_FLASY2022.pdf

09:30 Implications of the Zero 1-3 Flavour Mixing Hypothesis: Predictions for \theta_{23}^PMNS and \delta_PMNS$

We revisit mixing sum rule relations in the lepton and quark sectors under the assumption that the 1-3 elements of the flavour mixing matrices ($V^u_L,V^d_L,V^e_L,V^\nu_L$) are zero in the flavour basis. We consider the exact relations resulting from the validity of this zero 1-3 flavour mixing hypothesis and analyse their implications based on the current experimental data, including effects from RG running. In particular, we analyse how the existing precise measurement of $\theta_{13}^\mathrm{PMNS}$ allows to derive predictions for $\theta_{23}^\mathrm{PMNS}$ in models with constrained $\theta_{12}^\mathrm{e}$. As examples, we discuss the predictions for $\theta_{23}^\mathrm{PMNS}$ which arise in classes of Pati-Salam models and SU(5) GUTs that relate $\theta_{12}^\mathrm{e}$ to $\theta_{12}^\mathrm{d}$. We also derive a novel lepton phase sum rule, valid under the additional assumption of small charged lepton mixing contributions. We furthermore point out that, in the context of GUT flavour models, the quark and lepton CP violating phases $\delta^\mathrm{CKM}$ and $\delta^\mathrm{PMNS}$ can both be predicted from a single imaginary element in the mass matrices.

Speaker: Stefan Antusch

Antusch_Flasy_2022.pdf

10:00 Momentum Dependence in Higgs Couplings from Physics Beyond the Standard Model

I will consider momentum dependent effects in Higgs couplings generated by physics beyond the standard model. I will explore a model dependent approach, in which we can compute fully the non-local effects from physics not directly reachable by the LHC energy. This information is encapsulated in form factors. I will briefly compare this method with the effective field theory approach. I will then consider a few examples generating these effects in Higgs couplings and consider the phenomenological consequences for their detection at the LHC and future facilities.

Speaker: Gustavo Burdman (University of Sao Paulo, Brazil)

Burdman_FLASY.pdf

10:30 → 11:00 Coffee Break

11:00 → 12:30 Morning Session

Convener: Manfred Lindner

11:00 Precision CEvNS

I will discuss the impact of quenching factor and nuclear form factor uncertainties on the interpretation of coherent elastic neutrino-nucleus scattering data.

Speaker: Danny Marfatia

Marfatia_FLASY2022.pdf

11:30 Coherent elastic neutrino-nucleus scattering in the Standard Model and beyond

In this talk, I will present the physics potential of the coherent elastic neutrino-nucleus scattering (CEvNS) process. I will first briefly review the status of current observations. Then I will comment about their implications for both precision tests of the Standard Model and for new physics in the neutrino sector. Finally I will discuss the relevance of these measurements for direct dark matter detection probes.

Speaker: Valentina De Romeri

De_Romeri_FLASY22.pdf

12:00 Double Beta Decay as a Probe of New Physics

Neutrinoless double beta decay is crucial in determining the nature of neutrinos, and thereby the mechanism beyond the Standard Model (SM) with which they acquire their masses. I will review searches for neutrinoless double beta decay and discuss the prospects and consequences of observing neutrinoless double beta decay. I will likewise highlight related modes such as Majoron emission and two-neutrino double beta decay. The latter, SM-allowed process is being measured with increasing precision as experiments become more sensitive and can itself be used as a probe of New Physics.

Speaker: Frank F Deppisch

deppisch-flasy22.pdf

12:30 → 14:30 Lunch Break

14:30 → 15:30 Afternoon Session

Convener: Jose Valle

14:30 Universal inverse seesaw and radiative neutrino masses

In this talk I will describe a theory where the Inverse seesaw mechanism is implemented not only in the neutrino sector but also in the SM charged fermion sector in order to explain the pattern of SM fermion masses. To the best of my knowledge, that model corresponds to the first implementation of the inverse seesaw mechanism for the charged fermion sector. I will discuss its implications in the muon and electon anomalous magnetic moments, meson oscillations, dark matter and leptogenesis. Finally, I will explain a scotogenic neutrino mass model where the fermionic particles mediating the one-loop level radiative seesaw mechanism are crucial for achieving successful gauge coupling unification.

Speaker: Antonio Enrique Cárcamo Hernández

TalkACarcamoHFLASY2022.pdf

15:00 Kaon and B-meson decays with neutrino pairs

We discuss rare kaon and B meson decays with final state neutrino pairs in the context of non-standard neutrino interactions that add incoherently to standard model rates. We use existing experimental limits to constrain neutrino lepton flavour violation, neutrino lepton number violation, and additional light neutrino species contributions to these modes.

Speaker: German Valencia (Monash University (AU))

valencia_flasy.pdf

15:30 → 15:45 Closing

16:00 → 16:30 Coffee Break