In the bound state in continuum (BIC) the mass of a composite particle is greater than the total mass of its constituent particles. The BIC states that are stable due to confinement mechanisms, have been found in various fields but particle physics has evolved without analyzing these states. The work's idea is to apply the BIC phenomenon to some elementary particles. The study focuses on a composite fermion of the three light leptons, $(e^{-}e^{+}e^{\pm})_{BIC}$. In the present theory the free electron and free positron is treated as different particles, each being characterized by the complete set of the Dirac plane waves. Using the Bethe-Salpeter equation, the wave function of the fermion with the mass of 207 electron masses was found numerically. The results obtained predict the particle radius equal to 65.9 Fm. The representation of muons as the composite fermions formed by the three electron-like leptons in the BIC states, is analyzed.
In this talk, I will present the status of lepton flavor physics in composite Higgs models with partial compositeness in the light of recent data in the lepton sector. I will consider anarchic flavor setups, scenarios with flavor symmetries, and minimal incarnations of the see-saw mechanism that naturally predict non-negligible lepton compositeness. The focus will be on lepton flavor violating processes, dipole moments, and on probes of lepton flavor universality, all providing stringent tests of partial compositeness. The expected size of effects in the different approaches to lepton flavor a…
A compsite model of quarks and leptons is proposed. The quarks and leptons are given by three body states which are composed of constituents $(w_1, w_2, c_1, c_2, c_3)$ of SU(5)$_{flavor}$ and $(f_1, f_2, f_3)$ of SU(3)$_{family}$
Partial compositeness as a theory of flavor in the lepton sector is assessed. We begin presenting the first systematic analysis of neutrino mass generation in this context, and identifying the distinctive mass textures. We then update the bounds from charged lepton flavor and CP violating observables. We put forward a $U(1)^3\times CP$ symmetry of the composite sector, in order to allow the new physics to be not far above the TeV scale. This hypothesis effectively suppresses the new contributions to the electron EDM and $μ\to eγ$, by far the most constraining observables, and results in a nove…
Neutrino Masses from an A4 Symmetry in Holographic Composite Higgs Models
我们表明，全息复合希格斯模型与离散A4对称性自然预测层次带电轻子质量和近似的三双极大轻子混合与正确的中微子质量的规模。它们还满足电弱精密测试、轻子味破坏和轻子混合在大范围参数空间中的电流约束。在这些模型中出现了两个现象学上相关的特征。首先，对轻子汤川耦合的额外抑制使τ轻子比从其质量天真地预期的更复杂。因此，新的轻轻子共振，质量低至几百GeV，大耦合到τ和一个非常典型的对撞机现象，是很有可能的。其次，离散对称性A4与模型结构一起提供了双层风味保护，其允许将树水平介导的过程保持在当前实验极限以下。然而，违反轻子味道的单圈过程，如mu -> e gamma，可能在未来的实验中观察到。
We consider the $L$-$R$ symmetric composite model for quarks and leptons where constituent preons possessing some local $SU(N)_{MF}$ metaflavor symmetry are bound by the chiral $SO(n)_{L}\times SO(n)_{R}$ gauge metacolor forces. The strengthening of the 't Hooft's anomaly matching condition, when the massless fermion composites are required to complete a single representation of the $SU(N)_{MF}$ rather than some set of its representations, allows to fix the number of basic metaflavors $N$. Particularly, just eight left-handed and eight right-handed preons and their composites preserving the gl…
Within the context of composite Higgs models, recent hints on lepton-flavour non-universality in $B$ decays can be explained by a vector resonance $V$ with sizeable couplings to the Standard Model leptons ($\ell$). We argue that, in such a case, spin-$1/2$ leptonic resonances ($L$) are most probably light enough to open the decay mode $V \rightarrow L\ell$. This implies, in combination with the fact that couplings between composite resonances are much larger than those between composite and elementary fields, that this new decay can be important. In this paper, we explore under which condition…
We present a model for third-family quark-lepton unification at the TeV scale featuring a composite Higgs sector. The model is based on a variant of the Pati-Salam model, the so-called 4321 model, consisting of the gauge group $SU(4)\times SU(3)^\prime\times SU(2)_L\times U(1)_X$. The spontaneous symmetry breaking to the SM gauge group is triggered dynamically by a QCD-like confining sector. The same strong dynamics also produces the Higgs as a pseudo Nambu-Goldstone boson, connecting the energy scales of both sectors. The model predicts a massive $U_1$ vector leptoquark coupled dominantly to …
We present a new class of models of lepton flavor in the composite Higgs framework. Following the concept of minimality, they lead to a rich phenomenology in good agreement with the current experimental picture. Because of a unification of the right-handed leptons, our scenario is very predictive and can naturally lead to a violation of lepton-flavor universality in neutral current interactions. We will show that, in particular, the anomaly in $R_K= {\cal B}(B \to K μ^+ μ^-)/{\cal B}(B \to K e^+ e^-)$, found by LHCb, can be addressed, while other constraints from quark- and lepton-flavor physi…
In these proceedings we discuss a flavor-safe explanation of the anomaly found in $R_K= {\cal B}(B \to K μ^+ μ^-)/{\cal B}(B \to K e^+ e^-)$ by LHCb, within the framework of composite Higgs models. We present a model featuring a non-negligible degree of compositeness for all three generations of right-handed leptons, which leads to a violation of lepton-flavor universality in neutral current interactions while other constraints from quark- and lepton-flavor physics are met. Moreoever, the particular embedding of the lepton sector considered in this setup provides a parametrically enhanded cont…
Composite Higgs models feature new strong dynamics leading to the description of the Higgs boson as a bound state arising from the breaking of a global (flavour) symmetry. These models generally include light states generated by the same dynamics, the detection of which may present the first observable signs of compositeness. One such state is a pseudo-scalar boson resulting from the breaking of a $U(1)$ symmetry common to most composite setups, and whose hints are expected to be visible through low-mass resonance searches at present and future hadron and lepton colliders. In this work we stud…
We consider the production of excited electrons with spin-1/2 at the future SPPC-based electron-proton colliders with center-of-mass energies of $8.4$, $11.6$, $26.6$ and $36.8$ TeV. These exotic particles are predicted in the composite models. We calculate the production cross-sections and concentrate on the photon decay channel of the excited electrons with the process of $ep\rightarrow e^{\star}X\rightarrow eγX$ . The pseudorapidity and transverse momentum distributions of the electrons and photons in the final-state have been plotted in order to determine the kinematical cuts best suited f…
Minimal Composite Higgs Models (MCHM) have long provided a solution to the hierarchy problem of the Standard Model, yet suffer from various sources of fine tuning that are becoming increasingly problematic with the lack of new physics observations at the LHC. We develop a new fine tuning measure that accurately counts each contribution to fine tuning (single, double, triple, etc) that can occur in a theory with $n_p$ parameters, that must reproduce $n_o$ observables. We then use a novel scanning procedure to perform a comprehensive study of three different two-site, 4D, $SO(5)\rightarrow SO(4)…
In the composite Higgs models, originally proposed by Georgi and Kaplan, the Higgs boson is a pseudo Nambu-Goldstone boson (pNGB) of spontaneous breaking of a global symmetry. In the minimal version of such models, global SO(5) symmetry is spontaneously broken to SO(4), and the pNGBs form an isospin doublet field, which corresponds to the Higgs doublet in the Standard Model (SM). Predicted coupling constants of the Higgs boson can in general deviate from the SM predictions, depending on the compositeness parameter. The deviation pattern is determined also by the detail of the matter sector. We…
In the chiral $SU(15)$ gauge theory presented here, the quarks and leptons are bound states ("prebaryons") of massless preons. The Standard Model charges of the preons imply 3 generations of quarks and leptons, plus some vectorlike fermions lighter than the confining scale $Λ_{\rm pre}$. Under certain assumptions about the chiral dynamics, bound states of two prebaryons behave as Higgs fields. The QCD and electroweak groups may unify above $Λ_{\rm pre}$, while $SU(15)$ prevents rapid proton decay.
We propose a model which explains the baryon asymmetry of the universe and dark matter relic density at the same time. In this model, dark matter candidate is the dark baryon composed by dark quarks. A scalar mediator, which couples to the standard model leptons and dark quarks, is introduced to generate the asymmetry of baryon and dark baryon simultaneously. Direct detection and collider detection of this model are studied. We find that current underground direct detection experiments and LHC can hardly detect this model. But future lepton colliders, such as CEPC, have great potential to dete…
Quarks, Leptons as Fermion-Boson Composite Objects and Flavor-Mixings by Substructure Dynamics
A fermion-boson-type composite model for quarks and leptons is proposed. Elementary fields are only one kind of spin-1/2 and spin-0 preon. Both are in the global supersymmetric pair with the common electric charge of e/6 and belong to the fundamental representations of (3,2,2) under the spontaneously unbroken SU(3)_C*SU(2)_L*SU(2)_R gauge symmetry induced necessarily by the concept of ``Cartan connection'' equipped with ``Soldering Mechanism''. Preons are composed into subquarks which are ``intermediate clusters'' towards quarks and leptons. The mechanism of making higher generations is obtain…
In composite Higgs (CH) models, large mixings between the top quark and the new strongly interacting sector are required to generate its sizeable Yukawa coupling. Precise measurements involving top as well as left-handed bottom quarks therefore offer an interesting opportunity to probe such new physics scenarios. We study the impact of third-generation-quark pair production at future lepton colliders, translating prospective effective-field-theory sensitivities into the CH parameter space. Our results show that one can probe a significant fraction of the natural CH parameter space through the …
The leptons, quarks and weak bosons are bound states of new constituents. An isosinglet weak boson should exist, the X particle, which might have a mass of about 400 GeV and a width of about 20 GeV.
Some aspects of electroweak physics for a composite Higgs boson: application to the Z gauge boson decaying into two leptons and two pseudoscalar mesons
