Strong coupling and discrete symmetry can work together to generate the flavour structure of the Standard Model. It is proposed that the full UV theory has a discrete flavour symmetry, typically only associated with tribimaximal mixing in the neutrino sector. Hierarchies in the particle masses and mixing matrices ...

We study the set of models in which the Standard Model symmetry is extended with the flavour group A 4 and there are three copies of the Standard Model Higgs that transform as a triplet under this group. In this setup, new channels for flavour violating processes can be studied once the A 4 representations of the fermions in the theory ...

With the standard model gauge group and the three standard left-handed Weyl neutrinos, two minimal scenarios are investigated where an arbitrary non-abelian lepton flavour symmetry group G(sub H) is responsible for a light neutrino with a large magnetic m...

We have studied the restoration of chiral symmetry in lattice QCD at the finite temperature transition from hadronic matter to a quark-gluon plasma. By measuring the screening masses of flavour singlet and non-singlet meson excitations, we have seen evidence that, although flavour chiral symmetry is restored at ...

I review progress in calculating strange quark and antiquark distributions of the nucleon using the meson cloud model. This progress parallels that of the meson cloud model, which is now a useful theoretical basis for understanding symmetry breaking in nucleon parton distribution functions. I examine the breaking of symmetries involving strange quarks and ...

I review progress in calculating strange quark and antiquark distributions of the nucleon using the meson cloud model. This progress parallels that of the meson cloud model, which is now a useful theoretical basis for understanding symmetry breaking in nucleon parton distribution functions. I examine the breaking of symmetries involving strange quarks and ...

We study classes of models which are based on some discrete family symmetry which is completely broken such that the observed neutrino flavour symmetry emerges indirectly as an accidental symmetry. For such ``indirect'' models we discuss the D-term flavon vacuum alignments which are required for such an accidental ...

We analyze CP violation in supersymmetry with Effective Minimal Flavour Violation, as recently proposed in [1]. Unlike the case of standard Minimal Flavour Violation, we show that all the phases allowed by the flavour symmetry can be sizable without violating existing Electric Dipole Moment constraints, thus ...

We apply 't Hooft's anomaly constraint and flavour independence requirement to the rishon model. The limit gc-->0 is taken and we assume the full flavour symmetry SU(6)L � SU(6)R to be partially broken to SU(3)L � SU(3)R. Anomaly equations are constructed in the preserved global flavour ...

The flavour symmetry of the Standard Model (SM) gauge sector is broken by the fermion Yukawa couplings. Promoting the Yukawa matrices to scalar spurion fields, one can break the flavour symmetry spontaneously by giving appropriate vacuum expectation values (VEVs) to the spurion fields, and one encounters Goldstone ...

Making use of the generating functional of the non-Abelian flavour anomalies of QCD, a gauge invariant phenomenological Lagrangian of pseudoscalar and vector mesons was constructed, which is equivalent to the extended Wess-Zumino Lagrangian in the low ene...

The massive Schwinger model with two flavours is studied using the local hamiltonian lattice Monte Carlo method. Chiral symmetry breaking is studied using the fermion condensate as order parameter. For a small ratio of the two fermion masses, degeneracy of the two flavours is found. For a large ratio of the masses, the heavy ...

If supersymmetry (SUSY) will be discovered, successful models of flavour not only have to provide an explanation of the flavour structure of the Standard Model fermions, but also of the flavour structure of their scalar superpartners. We discuss aspects of such "SUSY flavour" models, towards predicting both ...

The exact alignment of the Yukawa structures on multi-Higgs doublet models provides cancellation of tree-level flavour changing couplings of neutral scalar fields. We show that family symmetries can provide a suitable justification for the Yukawa alignment.

It is shown that an exact chiral symmetry can be described for Dirac-Kahler fermions using the two complexes of the geometric discretization. This principle is extended to describe exact flavour projection and it is shown that this necessitates the introduction of a new operator and two new structures of complex. To describe simultaneous chiral and ...

A flavour gauge theory is observable only if the symmetry is broken at relatively low energies. The intrinsic parity-violation of the fermion representations in a flavour theory describing quark, lepton and higgsino masses and mixings generically requires anomaly cancellation by new fermions. Benchmark supersymmetric ...

The observation of neutrino oscillations has demonstrated that individual lepton numbers are not conserved. However, lepton flavour violation has so far not been seen in processes involving charged leptons, despite many models beyond the standard model predicting sizeable rates for decays such as ??e+?. In this talk charged lepton flavour oscillations is ...

We have studied the restoration of chiral symmetry in lattice QCD at the finite temperature transition from hadronic matter to a quark-gluon plasma. By measuring the screening masses of flavour singlet and non-singlet meson excitations, we have seen evide...

A new class of particle physics models of inflation based on the phase transition associated with the spontaneous breaking of family symmetry is proposed. The Higgs fields responsible for the breaking of family symmetry, the flavons, are natural inflaton candidates or waterfall fields in hybrid inflation. This opens up a rich vein of possible inflation ...

We build on a recent paper by Grinstein, Redi and Villadoro, where a seesaw like mechanism for quark masses was derived in the context of spontaneously broken gauged flavour symmetries. The see-saw mechanism is induced by heavy Dirac fermions which are added to the Standard Model spectrum in order to render the flavour ...

Induced flavour-changing neutral currents (FCNC) in supersymmetric unified theories are investigated both in models with the standard SU(2)sub(L) x U(1) gauge symmetry and in models with an extra U tilde(1) gauge symmetry. Supersymmetric extension of the ...

We discuss in what way flavour symmetry breaking through nondegenerate light quark masses and through the mixing of {pi}{sup 0}, {eta}, {eta}{prime} modifies the Goldberger-Treiman relations for the triplet, octet and in particular, for the generalizations to the flavour singlet channel. We derive simple new algebraic expressions for ...

The most general two-Higgs doublet model contains new sources of flavour violation that are usually in conflict with the experimental constraints. One possibility to suppress the exotic contribution to the flavour changing neutral currents consists on imposing the alignment of the Yukawa couplings. This condition presumably holds at a high-energy scale and ...

We study effects of pole-model-induced SU(4)-symmetry breaking in parity violating amplitudes of Cabibbo-favoured nonleptonic decays of charmed baryons. A simple technique generalizing the expressions of current algebra to the case of flavour symmetry bre...

We survey some of the recent promising developments in the search for the theory behind neutrino mass and tri-bimaximal mixing, and indeed all fermion masses and mixing. We focus in particular on models with discrete family symmetry and unification, and show how such models can also solve the SUSY flavour and CP problems. We also discuss the theoretical ...

We show how quantum corrections above the GUT scale can result in supersymmetric models where lepton flavour violation is naturally suppressed, in agreement with all experimental bounds. Within this framework, a soft term structure as predicted by an Abelian flavour symmetry combined with SU(5) RGEs for scales above MGUT, results to an ...

Elementary particle physics in the next decade will be focused on the investigation of the origin of electroweak symmetry breaking and the search for extensions of the Standard Model (SM) at the TeV scale. The discovery of New Physics will likely produce ...

From a necessary condition for 'open door' decays of tetraquarks into two pseudoscalar mesons or into a vector and pseudoscalar mesons, we deduce that the lighter states may have strong couplings into these final states.

We formulate a consistent model predicting, in the leading order approximation, maximal atmospheric mixing angle, vanishing reactor angle and tan ? 12 = 1 /? where ? = {{{( {1 + sqrt {5} } )}} / {2} .} is the Golden Ratio. The model is based on the flavour symmetry A 5 � Z 5 � Z 3, spontaneously broken by a set of flavon fields. By minimizing the ...

We consider an extension of the Standard Model in which the symmetry is enlarged by a global flavour factor A 4 and the scalar sector accounts for three copies of the Standard Model Higgs, transforming as a triplet of A 4. In this context, we study the most general scalar potential and its minima, performing for each of them a model independent analysis on ...

We discuss how a Le-L?-L? flavour symmetry that is softly broken leads to keV sterile neutrinos, which are a prime candidate for Warm Dark Matter. This is to our knowledge the first model where flavour symmetries are applied simultaneously to active and sterile neutrinos explaining at the same time active neutrino ...

We study renormalization group running effects on neutrino mixing patterns when a (type I) seesaw model is implemented by suitable flavour symmetries. We are particularly interested in mass-independent mixing patterns to which the widely studied tribimaximal mixing pattern belongs. In this class of flavour models, the running ...

We analyze the most general dimension-six effective Lagrangian, invariant under the flavour symmetry A�Z�U(1 proposed to reproduce the near tri-bimaximal lepton mixing observed in neutrino oscillations. The effective Lagrangian includes four-lepton operators that violate the individual lepton numbers in the limit of exact flavour ...

We perform an extensive study of FCNC and CP Violation within Supersymmetric (SUSY) theories with particular emphasis put on processes governed by b?s transitions and of their correlations with processes governed by b?d transitions, s?d transitions, D0-D� oscillations, lepton flavour violating decays, electric dipole moments and (. We first perform a comprehensive ...

We perform an extensive study of FCNC and CP Violation within Supersymmetric (SUSY) theories with particular emphasis put on processes governed by b->s transitions and of their correlations with processes governed by b->d transitions, s->d transitions, $D^0-\\bar D^0$ oscillations, lepton flavour violating decays, electric dipole moments and (g-2)_mu. We first perform ...

We show that existing data suggest a simple scenario in which the nucleon and the Delta and Roper resonances act as chiral partners in a reducible representation of the full QCD chiral symmetry group. We discuss the peculiar interpretation of this scenario using spin-flavour symmetries of the naive constituent quark model, as well as ...

A generalized permutation group is introduced as a possible horizontal symmetry for SU(2)subL x U(1) gauge theories. It leads to the unique two generation quark mass matrices with a correct prediction for the Cabibbo angle. For three generations the model...

We discuss a particularly symmetric model of neutrino mixings where, with good accuracy, the atmospheric mixing angle ? is maximal, ?=0 and the solar angle satisfies sin?=1/3 (Harrison Perkins Scott (HPS) matrix). The discrete symmetry A is a suitable symmetry group for the realization of this type of model. We construct a model where the HPS matrix is ...

Both Grand Unified symmetries and discrete flavour symmetries are appealing ways to describe apparent structures in the gauge and flavour sectors of the Standard Model. Both symmetries put constraints on the high energy behaviour of the theory. This can give rise to unexpected interplay when ...

The impact of right-handed currents in both charged- and neutral-current flavour-violating processes is analysed by means of an effective theory approach. More explicitly, we analyse the structure of dimension-six operators assuming a left-right symmetric flavour group, commuting with an underlying SU(2�SU(2�U(1 global symmetry, ...

We perform a detailed analysis of thermal leptogenesis in the framework of seesaw models which approximately conserve lepton number. These models are known to allow for large Yukawa couplings and a low seesaw scale in agreement with neutrino mass constraints, and hence to lead to large lepton flavour violating rates that can be probed experimentally. Although large Yukawa ...

We analyze the most natural formulations of the minimal lepton flavour violation hypothesis compatible with a type-I seesaw structure with three heavy singlet neutrinos N, and satisfying the requirement of being predictive, in the sense that all LFV effects can be expressed in terms of low energy observables. We find a new interesting realization based on the ...

We compute the branching ratios for ??e?, ???? and ??e? in a supersymmetric model invariant under the flavour symmetry group A�Z�U(1, in which near tri-bimaximal lepton mixing is naturally predicted. At leading order in the small symmetry breaking parameter u, which is of the same order as the reactor mixing angle ?, we find that ...

The evidence for point-like quarks and their quantum numbers is reviewed, together with the arguments which suggest a `colour' degree of freedom for them, corresponding to an SU(3)C colour symmetry. Gauging the colour current leads directly to the theory known as quantum chromodynamics, a theory which is renormalizable, has asymptotic freedom, and may have quite naturally both ...

In the two Higgs doublet model, natural flavour conservation can be achieved through the use of a discrete Z symmetry. A less restrictive condition is the requirement of alignment in the Yukawa sector. So far, alignment has been an ansatz, not rooted in a specific model. In this Letter we present a model for alignment, which starts with 2+N Higgs doublets, ...

We construct a simple model of fermion masses based on a spontaneously broken S�Z flavour group. At the leading order, in the neutrino sector S is broken down to a ? ? parity subgroup that enforces a maximal atmospheric mixing angle and a vanishing ?. In the charged lepton sector the ? ? parity is maximally broken and the resulting mass matrix is nearly diagonal. The charged ...

The rishon model is studied in the limit gc --> 0, ? --> 0 when its global flavour symmetry is SU(6) � SU(6) � U(1) analogous to six massless flavour QCD. Recently it was shown that the ad hoc breaking SU(6) � SU(6) --> SU(3) � SU(3) allows the anomaly constraint to be satisfied. In this paper this is shown to be but ...

We study flavour violation in a supersymmetric SO(10) implementation of the type II seesaw mechanism, which provides a predictive realization of triplet leptogenesis. The experimental upper bounds on lepton flavour violating processes have a significant impact on the leptogenesis dynamics, in particular they exclude the strong washout regime. Requiring ...

We propose a supersymmetric A4�SU(5) model of quasidegenerate neutrinos which predicts the effective neutrino mass mee relevant for neutrinoless double beta decay to be proportional to the neutrino mass scale, thereby allowing its determination approximately independently of unknown Majorana phases. Such a natural quasidegeneracy is achieved by using ...

Rather than sticking to the full U(3)3 approximate symmetry normally invoked in Minimal Flavour Violation, we analyze the consequences on the current flavour data of a suitably broken U(2)3 symmetry acting on the first two generations of quarks and squarks. A definite correlation emerges between the ?F=2 amplitudes ...

In the present work we study a relativistic quark model at finite temperature and density with non-local quark-antiquark and quark-quark interactions with SU(2) flavour and SU(3) color symmetries. After proper bosonization, we analyze the structure of the corresponding phase diagram and discuss the competition between the chiral and 2SC phases.

It is now possible to formulate QCD on a space-time lattice with correct chiral and flavour symmetries, and to simulate the dynamical effects of the u, d and s quarks with masses close to their physical values. This short review for non-experts describes the status of the simulation results, and how they are helping us to understand the strong interaction, ...

By the end of 2009 the KLOE-2 detector is expected to start data taking at the improved DAphiNE ?-factory of the Laboratori Nazionali di Frascati of INFN. The KLOE-2 physics program is wide, spanning from studies on neutral kaon quantum interferometry, to precise tests of lepton flavour violation, to low energy QCD studies. In this paper, the status of the project is ...

NLO fits, a polarised high energy collider would be required to provide the necessary large range in Q target fragments hadron initial nucleon p = ( E ,p k=(E,k) Fig. 1. Schematic diagram of a deep inelastic . The more dangerous assumptions of SU(3) flavour symmetry and that the strange sea quarks are unpolarised

We present results for the phase diagram of QCD with two massless quark flavours as obtained from a first-principles functional renormalisation group approach. In particular we compute order parameters for chiral symmetry breaking and quark confinement at vanishing and non-zero imaginary chemical potential. Our analytical and numerical results suggest a ...

Charmless B ? PP decays are studied using flavour SU(3) symmetry. Amplitude with charming penguin topology is considered for two cases: with zero and with arbitrary strong phase. Two sets of data (an older and the most recent one) are used in the fits, so that the stability of the fits is tested. It is shown that within the present uncertainties in the ...

We calculate low-energy meson decay processes and pion-pion scattering lengths in a two-flavour linear sigma model with global chiral symmetry, exploring the scenario in which the scalar mesons f0 (600) and a0 (980) are assumed to be qq states. �

The decay constants of B and D mesons are computed in quenched lattice QCD at two different values of the coupling. The action and operators are ? (a) improved with non-perturbative coefficients where available. The results and systematic errors are discussed in detail. Results for vector decay constants, flavour symmetry breaking ratios of decay ...

A composite quark model based on the symmetry group SU(10)sub(flavour) x SU(10)sub(colour) with the assumption of mass non-degenerate sub-quarks is considered. Magnetic moments of quarks and sub-quarks are obtained from the observed nucleon magnetic momen...

This document is part of Subvolume A �Theory and Experiments� of Volume 21 �Elementary Particles� of Landolt-B�rnstein - Group I �Elementary Particles, Nuclei and Atoms�. It contains of the Chapter �10 Symmetry Violations and Quark Flavour Physics� the Section �10.7 Weak quark mixing and the CKM matrix�.

INTRODUCTION An important element in the testing of the Kobayashi--Maskawa picture of CP violation to an exciting picture [21]. 2 B ! #25;K DECAYS Using the isospin flavour symmetry of strong interactions, relations;n) ; � (c;n) ; #17; : (4) Here q (c;n) denotes the ratio of electroweak (EW) penguins to ``trees'', r (c

Chiral symmetry is known to be decisive for an understanding of the low-energy sector of strong interactions. It is thus important for a model of relativistic heavy ion collisions to incorporate the dynamical breaking and restoration of chiral symmetry. Thus we study an expansion scenario for a quark-meson plasma using the Nambu-Jona-Lasinio (NJL) model in ...

The LHC is set to achieve a total 14 TeV collision energy for every pair of protons colliding. At this energy it will be possible to study interactions of the SM particles that may contain particles beyond it. We therefore will continue improving our understanding of particle physics, at the very least. Ideally many particles would be discovered and its interactions would be studied. A framework ...

The value of the nucleon's flavour-singlet axial-charge extracted from polarised deep inelastic scattering is sensitive to the value of the octet axial-charge gA(8) which is usually taken from an analysis of hyperon ?-decays within the framework of SU(3) symmetry, namely 0.58�0.03. Using the Cloudy Bag model we find that the value of gA(8) is reduced by ...

We study spectral distortions of diffuse ultra-high energy (UHE) neutrino flavour fluxes resulting due to physics beyond the Standard Model (SM). Even large spectral differences between flavours at the source are massaged into a common shape at earth by SM oscillations, thus, any significant observed spectral differences are an indicator of new physics ...

Diagonal and off-diagonal flavour and conserved charge susceptibilities reveal the prevalent degrees of freedom of heated strongly-interacting matter. Results obtained from lattice simulations are compared with various model estimates in an effort to weed down various possible pictures of a quark-gluon plasma. We argue that the vanishing of the off-diagonal quark ...