Families Of Leptons Research Articles

FUNDAMENTAL PARTICLE STRUCTURE IN THE COSMOLOGICAL DARK MATTER

The nonbaryonic dark matter of the universe is assumed to consist of new stable forms of matter. Their stability reflects symmetry of micro-world and mechanisms of its symmetry breaking. Particle candidates for cosmological dark matter are lightest particles that bear new conserved quantum numbers. Dark matter particles may represent ideal gas of noninteracting particles. Self-interacting dark matter weakly or superweakly coupled to ordinary matter is also possible, reflecting nontrivial pattern of particle symmetry in the hidden sector of particle theory. In the early universe the structure of particle symmetry breaking gives rise to cosmological phase transitions, from which macroscopic cosmological defects or primordial nonlinear structures can be originated. Primordial black holes (PBHs) can be not only a candidate for dark matter, but also represent a universal probe for superhigh energy physics in the early universe. Evaporating PBHs turn to be a source of even superweakly interacting particles, while clouds of massive PBHs can serve as nonlinear seeds for galaxy formation. The observed broken symmetry of the three known families may provide a simultaneous solution for the problems of the mass of neutrino and strong CP-violation in the unique framework of models of horizontal unification. Dark matter candidates can also appear in the new families of quarks and leptons and the existence of new stable charged leptons and quarks is possible, hidden in elusive "dark atoms." Such possibility, strongly restricted by the constraints on anomalous isotopes of light elements, is not excluded in scenarios that predict stable double charged particles. The excessive -2 charged particles are bound in these scenarios with primordial helium in O-helium "atoms," maintaining specific nuclear-interacting form of the dark matter, which may provide an interesting solution for the puzzles of the direct dark matter searches. In the context of cosmoparticle physics, studying fundamental relationship of micro- and macro-worlds, the problem of cosmological dark matter implies cross disciplinary theoretical, experimental and observational studies for its solution.

Lepton Electric Charge Swap at the 10 TeV Energy Scale

We investigate the nature of the dark matter by proposing a mechanism for the breaking of local rotational symmetry between ordinary third family leptons and proposed non-regular leptons at energy scales below 10 TeV. This symmetry breaking mechanism involves electric charge swap between ordinary families of leptons can and produces highly massive non-regular leptons of order O (1 TeV) mass unobservable at energy scales below 10 TeV (the scale of LEP I, II and neutrino oscillation experiments). Electric charge swap between ordinary families of leptons produces heavy neutral non-regular leptons with order O (1 TeV) masses, which may form cold dark matter. The existence of these proposed leptons can be tested once the Large Hadron Collider (LHC) becomes operative at 10 TeV energy-scales. This proposition may have far reaching applications in astrophysics and cosmology.

Proton decay and the origin of quark and lepton mixing

It was recently proposed that all flavor mixing has a single source, namely the mixing of the three quark and lepton families with "extra" vectorlike fermions in 5 + 5-bar multiplets of SU(5). This was shown to lead to several testable predictions including neutrino masses and CP-violating phases. Here it is shown that the mixing angles within grand unified fermion multiplets are also predicted. Proton decay branching ratios would thus give several independent tests of the model. Certain model parameters could be determined independently from the quark and lepton spectrum and from proton decay.

Tera-leptons’ shadows over Sinister Universe

The role of Sinister Heavy Fermions in Glashow’s SU(3) × SU(2) × SU(2)′ × U(1) model is to offer in a unique frame relic helium-like products (an ingenious candidate to the dark matter puzzle), a solution to the See-Saw mechanism for light neutrino masses as well as to the strong CP violation problem in QCD. The Sinister model requires three additional families of leptons and quarks, but only the lightest of them, the heavy U-quark and E-electron, are stable. Apparently the final neutral heliumlike (UUUEE) state is an ideal evanescent dark-matter candidate. However, it is reached by multi-body interactions in the early Universe along a tail of more manifest secondary frozen blocks. They should be now here polluting the surrounding matter. Moreover, in opposition to effective $$U\bar U$$ pair annihilation, there is no such an early or late tera-lepton pairs suppression because: (a) electromagnetic interactions are weaker than nuclear ones and (b) the primordial helium nucleus (4He)++ is able to attract and capture (in the first three minutes) E − fixing it into a hybrid tera-helium ion trap. This leads to a pile up of (4HeE −)+ traces, a lethal compound for any Sinister Universe. This capture leaves no tera-lepton frozen in (Ep) relic, otherwise an ideal catalyzer to achieve effective late E + E − annihilations, possibly saving the model. The (4HeE −)+ Coulomb screening is also avoiding the synthesis of the desired (UUUEE) hidden dark matter gas. The (4HeE −)+ E − behave chemically like an anomalous hydrogen isotope. Also terapositronium relics (e − E +) are over-abundant, and they behave like an anomalous hydrogen atom: these gases do not fit by many orders of magnitude the known severe bounds on hydrogen anomalous isotope, making shadows hanging over a Sinister Universe. However a surprising and resolver role for Tera-Pions in UHECR astrophysics has been revealed.

Neutrino masses and mixing inA4models with three Higgs doublets

We study neutrino masses and mixing in the context of flavor models with ${A}_{4}$ symmetry, three scalar doublets in the triplet representation, and three lepton families. We show that there is no representation assignment that yields a dimension-5 mass operator consistent with experiment. We then consider a type-I seesaw with three heavy right-handed neutrinos, explaining in detail why it fails, and allowing us to show that agreement with the present neutrino oscillation data can be recovered with the inclusion of dimension-3 heavy neutrino mass terms that break softly the ${A}_{4}$ symmetry.

Inverted effective supersymmetry with combinedZ′and gravity mediation, and muon anomalous magnetic moment

Effective supersymmetry (SUSY), where the stop is the lightest squark, may run into a two-loop tachyonic problem in some ${Z}^{\ensuremath{'}}$ mediation models. In addition, a large $A$ term and/or a large stop mass are needed to have a $\ensuremath{\sim}126\text{ }\text{ }\mathrm{GeV}$ Higgs boson with three families of quarks and leptons. Thus, we suggest an inverted effective SUSY (IeffSUSY) where the stop mass is larger compared to those of the first two families. In this case, it is possible to have a significant correction to the anomalous magnetic moment of the muon. A three-family IeffSUSY in a ${Z}^{\ensuremath{'}}$ mediation scenario is explicitly studied with the ${Z}^{\ensuremath{'}}$ quantum number related to $B\ensuremath{-}L$. Here we adopt both the ${Z}^{\ensuremath{'}}$ mediation and gravity mediation, where the ${Z}^{\ensuremath{'}}$ mediation is the dominant one for the stop, while the gravity mediation is the dominant one for the muonic leptons and Higgs multiplets. We present a numerical study based on a specific anomaly-free model, and show the existence of the parameter region where all the phenomenological conditions are satisfied.

The Higgs Boson in the Periodic System of Elementary Particles

It is proposed that the observed Higgs Boson at the LHC is the Standard Model Higgs boson that adopts the existence of the hidden lepton condensate. The hidden lepton is in the forbidden lepton family, outside of the three lepton families of the Standard Model. Being forbidden, a single hidden lepton cannot exist alone; so it must exist in the lepton condensate as a composite of μ’ and μ’± hidden leptons and their corresponding antileptons. The calculated average mass of the hidden lepton condensate is 128.8 GeV in good agreements with the observed 125 or 126 GeV. The masses of the hidden lepton condensate and all elementary particles including leptons, quarks, and gauge bosons are derived from the periodic system of elementary particles. The calculated constituent masses are in good agreement with the observed values by using only four known constants: the number of the extra spatial dimensions in the eleven-dimensional membrane, the mass of electron, the mass of Z boson, and the fine structure constant.

The <i>Spin-Charge-Family</i> Theory Is Explaining the Origin of Families, of the Higgs and the Yukawa Couplings

The (extremely efficient) standard model of the elementary particles and fields makes several assumptions, which call for explanations. Any theory offering next step beyond the standard model must explain at least the existence and properties of families and their members and correspondingly the existence of the scalar Higgs and the Yukawa couplings, which in this model take care of masses of fermions and weak bosons and influence the decaying properties of families. The spin-charge-family theory [1-11] is offering a possible explanation for the assumptions of the standard model—for the appearance of families and their members (for the charges of a family members), for the gauge fields, for the scalar fields—interpreting the standard model as its low energy effective manifestation. The spin-charge-family theory predicts at the low energy regime two decoupled groups of four families of quarks and leptons. The predicted fourth family waits to be observed, while the stable fifth family is the candidate to form the dark matter. In this paper properties of families are analysed. The appearance of several scalar fields, all in the bosonic (adjoint) representations with respect to the family groups, while they are doublets with respect to the weak charge, is presented, their properties discussed, it is explained how these scalar fields can effectively be interpreted as the standard model Higgs and the Yukawa couplings. The spin-charge-family theory predicts that there are no supersymmetric partners of the observed fermions and bosons.

A Global SU(5) F-theory model with Wilson line breaking

We engineer compact SU(5) Grand Unified Theories in F-theory in which GUT-breaking is achieved by a discrete Wilson line. Because the internal gauge field is flat, these models avoid the high scale threshold corrections associated with hypercharge flux. Along the way, we exemplify the `local-to-global' approach in F-theory model building and demonstrate how the Tate divisor formalism can be used to address several challenges of extending local models to global ones. These include in particular the construction of G-fluxes that extend non-inherited bundles and the engineering of U(1) symmetries. We go beyond chirality computations and determine the precise (charged) massless spectrum, finding exactly three families of quarks and leptons but excessive doublet and/or triplet pairs in the Higgs sector (depending on the example) and vector-like exotics descending from the adjoint of SU(5)_{GUT}. Understanding why vector-like pairs persist in the Higgs sector without an obvious symmetry to protect them may shed light on new solutions to the mu problem in F-theory GUTs.

Measurement of the [formula omitted] production cross section at [formula omitted

We present a measurement of the cross section for W boson production in association with at least one b-quark jet in proton–antiproton collisions. The measurement is made using data corresponding to an integrated luminosity of 6.1 fb−1 recorded with the D0 detector at the Fermilab Tevatron pp¯ Collider at s=1.96 TeV. We measure an inclusive cross section of σ(W(→μν)+b+X)=1.04±0.05(stat.)±0.12(syst.) pb and σ(W(→eν)+b+X)=1.00±0.04(stat.)±0.12(syst.) pb in the phase space defined by pTν>25 GeV, pTb-jet>20 GeV, |ηb-jet|<1.1, and a muon (electron) with pTℓ>20 GeV and |ημ|<1.7 (|ηe|<1.1 or 1.5<|ηe|<2.5). The combined result per lepton family is σ(W(→ℓν)+b+X)=1.05±0.12(stat.+syst.) pb for |ηℓ|<1.7. The results are in agreement with predictions from next-to-leading order QCD calculations using mcfm, σ(W+b)⋅B(W→ℓν)=1.34−0.34+0.41(syst.) pb, and also with predictions from the sherpa and madgraph Monte Carlo event generators.

A zip-code for quarks, leptons and Higgs bosons

The location of matter fields and the pattern of gauge symmetry in extra dimensions are crucial ingredients for string model building. We analyze realistic MSSM models from the heterotic Z6 Mini-Landscape and extract those properties that are vital for their success. We find that Higgs bosons and the top quark are not localized in extra dimensions and live in the full D=10 dimensional space-time. The first two families of quarks and leptons, however, live at specific fixed points in extra dimensional space and exhibit a (discrete) family symmetry. Within a newly constructed Z2XZ4 orbifold framework we further elaborate on these location properties and the appearance of discrete symmetries. A similar geometrical picture emerges. This particular Zip-code for quarks, leptons and Higgs bosons seems to be of more general validity and thus a useful guideline for realistic model building in string theory.

Implications of ultrahigh energy neutrino flux constraints for Lorentz-invariance violating cosmogenic neutrinos

We consider the implications of Lorentz-invariance violation (LIV) on cosmogenic neutrino observations, with particular focus on the constraints imposed on several well-developed models for ultrahigh energy cosmogenic neutrino production by recent results from the ANITA long-duration balloon payload, and RICE at the South Pole. Under a scenario proposed originally by Coleman and Glashow, each lepton family may attain maximum velocities that can exceed $c$, leading to energy-loss through several interaction channels during propagation. We show that future observations of cosmogenic neutrinos will provide by far the most stringent limit on LIV in the neutrino sector. We derive the implied level of LIV required to suppress observation of predicted fluxes from several mainstream cosmogenic neutrino models, and specifically those recently constrained by the ANITA and RICE experiments. We simulate via detailed Monte Carlo code the propagation of cosmogenic neutrino fluxes in the presence of LIV-induced energy losses. We show that this process produces several detectable effects in the resulting attenuated neutrino spectra, even at LIV-induced neutrino superluminality of $({u}_{\ensuremath{\nu}}\ensuremath{-}c)/c\ensuremath{\simeq}{10}^{\ensuremath{-}26}$, about 13 orders of magnitude below current bounds.

A simple grand unified relation between neutrino mixing and quark mixing

It is proposed that all flavor mixing is caused by the mixing of the three quark and lepton families with vectorlike fermions in 5 + 5-bar multiplets of SU(5). This simple assumption implies that both V_{CKM} and U_{MNS} are generated by a single matrix. The entire 3-by-3 complex mass matrix of the neutrinos M_{nu} is then found to have a simple expression in terms of two complex parameters and an overall scale. Thus, all the presently unknown neutrino parameters are predicted. The best fits are for theta_{atm} less than or approximately 40 degrees. The leptonic Dirac CP phase is found to be somewhat greater than pi radians.

Onset of Magnetic Monopole-Antimonopole Condensation

We determine the critical strength of the effective electric coupling for the onset of Bose condensation of stable magnetic monopoles and antimonopoles in SU(2) Yang-Mills thermodynamics. Two scenarios are considered: infinitely fast and infinitely slow downward approaches of the critical temperature. Our results support the claim that the first lepton family and the weak interactions emerge from pure SU(2) gauge dynamics of scale MeV.

Muon [formula omitted] and lepton flavor violation in a two Higgs doublets model for the fourth generation

In the minimal Standard Model (SM) with four generations (the so-called SM4) and in “standard” two Higgs doublets model (2HDM) setups, e.g., the type II 2HDM with four fermion generations, the contribution of the 4th family heavy leptons to the muon magnetic moment is suppressed and cannot accommodate the measured ∼3σ access with respect to the SM prediction. We show that in a 2HDM for the 4th generation (the 4G2HDM), which we view as a low energy effective theory for dynamical electroweak symmetry breaking, with one of the Higgs doublets coupling only to the 4th family leptons and quarks (thus effectively addressing their large masses), the loop exchanges of the heavy 4th generation neutrino can account for the measured value of the muon anomalous magnetic moment. We also discuss the sensitivity of the lepton flavor violating decays μ→eγ and τ→μγ and of the decay Bs→μμ to the new couplings which control the muon g−2 in our model.

Running coupling in electroweak interactions of leptons from f(R)-gravity with torsion

The f(R)-gravitational theory with torsion is considered for one family of leptons; it is found that the torsion tensor gives rise to interactions having the structure of the weak forces, while the intrinsic non-linearity of the f(R) function provides an energy-dependent coupling: in this way, torsional f(R) gravity naturally generates both structure and strength of the electroweak interactions among leptons. This implies that the weak interactions among the lepton fields could be addressed as a geometric effect due to the interactions among spinors induced by the presence of torsion in the most general f(R) gravity. Phenomenological considerations are given.

Neutrino masses and a fourth generation of fermions

We study neutrino mass generation in models with four chiral families of leptons and quarks and four right handed neutrinos. Generically, in these models there are three different contributions to the light neutrino masses: the usual see-saw contribution, the tree-level contribution due to mixing of light neutrinos with neutrino of the fourth generation, and the two loop contribution due to the Majorana mass term of the fourth neutrino. We study properties of these contributions and their experimental bounds. The regions of the parameters (mixings of the fourth neutrino, masses of RH neutrino components, etc.) have been identified where various contributions dominate. New possibilities of a realisation of the flavour symmetries in the four family context are explored. In particular, we consider applications of the smallest groups, e.g. SG ( 20 , 3 ) , with irreducible representation 4 ̲ .

Towards a systematic construction of realistic D-brane models on a del Pezzo singularity

A systematic approach is followed in order to identify realistic D-brane models at toric del Pezzo singularities. Requiring quark and lepton spectrum and Yukawas from D3 branes and massless hypercharge, we are led to Pati-Salam extensions of the Standard Model. Hierarchies of masses, flavour mixings and control of couplings select higher order del Pezzo singularities, minimising the Higgs sector prefers toric del Pezzos with dP 3 providing the most successful compromise. Then a supersymmetric local string model is presented with the following properties at low energies: (i) the MSSM spectrum plus a local B − L gauge field or additional Higgs fields depending on the breaking pattern, (ii) a realistic hierarchy of quark and lepton masses and (iii) realistic flavour mixing between quark and lepton families with computable CKM and PMNS matrices, and CP violation consistent with observations. In this construction, kinetic terms are diagonal and under calculational control suppressing standard FCNC contributions. Proton decay operators of dimension 4, 5, 6 are suppressed, and gauge couplings can unify depending on the breaking scales from string scales at energies in the range 1012–1016 GeV, consistent with TeV soft-masses from moduli mediated supersymmetry breaking. The GUT scale model corresponds to D3 branes at dP 3 with two copies of the Pati-Salam gauge symmetry SU(4) × SU(2) R × SU(2) L . D-brane instantons generate a non-vanishing μ-term. Right handed sneutrinos can break the B − L symmetry and induce a see-saw mechanism of neutrino masses and R-parity violating operators with observable low-energy implications.

Discovering Technicolor

We provide a pedagogical introduction to extensions of the Standard Model in which the Higgs is composite. These extensions are known as models of dynamical electroweak symmetry breaking or, in brief, Technicolor. Material covered includes: motivations for Technicolor, the construction of underlying gauge theories leading to minimal models of Technicolor, the comparison with electroweak precision data, the low-energy effective theory, the spectrum of the states common to most of the Technicolor models, the decays of the composite particles and the experimental signals at the Large Hadron Collider. The level of the presentation is aimed at readers familiar with the Standard Model but who have little or no prior exposure to Technicolor. Several extensions of the Standard Model featuring a composite Higgs can be reduced to the effective Lagrangian introduced in the text. We establish the relevant experimental benchmarks for Vanilla, Running, Walking, and Custodial Technicolor, and a natural fourth family of leptons, by laying out the framework to discover these models at the Large Hadron Collider.

FOURTH GENERATION LEPTONS SEARCH IN γγ → ℓ-ℓ+ PROCESS AT THE CERN-LHC

The pp → pXp production is known to be one of the cleanest channels at the Large Hadron Collider (LHC). In this work, we investigate the potential of the exclusive pp → pℓ-ℓ+p process to probe fourth family leptons via anomalous interactions at the LHC by considering three forward detector acceptances: 0.0015 &lt; ξ &lt; 0.5, 0.0015 &lt; ξ &lt;0 .15, and 0.1 &lt; ξ &lt; 0.5. The sensitivity of the model parameters have been obtained at the 95% confidence level.