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We analyse the strength of CP violation in an extension of the standard model with an extra $Q=-1/3$ vector-like singlet quark, in the framework of the hypothesis of universality of strength of Yukawa couplings connecting standard quarks.…

High Energy Physics - Phenomenology · Physics 2013-07-02 G. C. Branco , H. R. Colaço Ferreira , A. G. Hessler , J. I. Silva-Marcos

We do a systematic analysis of the question of calculability of CKM matrix elements in terms of quark mass ratios, within the framework of the hypothesis of universality of strength for Yukawa couplings (USY), where all Yukawa couplings…

High Energy Physics - Phenomenology · Physics 2014-11-17 G. C. Branco , D. Emmanuel-Costa , J. I. Silva-Marcos

We study the question of calculability of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements within the framework of universal strength for Yukawa couplings (USY). We first classify all solutions leading to $m_u=m_d=0$ within USY and then…

High Energy Physics - Phenomenology · Physics 2009-10-28 G. C. Branco , J. I. Silva-Marcos

We give a procedure to construct a special class of symmetric quark mass matrices near the democratic limit of equal Yukawa couplings for each sector. It is shown that within appropriate weak-bases, the requirements of symmetry and…

High Energy Physics - Phenomenology · Physics 2009-10-31 J. I. Silva-Marcos

We analyse, within the framework of universal strength for Yukawa couplings (USY), various structures for the Dirac and Majorana neutrino mass matrices giving rise, through the see-saw mechanism, to a degenerate mass spectrum. A specific…

High Energy Physics - Phenomenology · Physics 2009-10-31 G. C. Branco , M. N. Rebelo , J. I. Silva-Marcos

We assume the universal Yukawa coupling (democratic mass matrix) with small violations for quarks, charged leptons and neutrinos masses. We could reproduce the mass hierarchy for quark masses and V_{CKM} matrix elements precisely. We adopt…

High Energy Physics - Phenomenology · Physics 2009-10-31 T. Teshima , T. Asai

The principles of finiteness and reduction of couplings can be applied to achieve Gauge-Yukawa Unification. It is found that the observed top-bottom hierarchy and the top quark mass naturally follow if there exists Gauge-Yukawa Unification…

High Energy Physics - Theory · Physics 2016-09-06 Jisuke Kubo , Myriam Mondragon , George Zoupanos

Based on the hierarchy exhibited by quarks masses at low energies, we assume that Yukawa couplings of up and down quarks are related by $Y_u\propto Y_d^2$ at grand unification scales. This ansatz gives rise to a symmetrical CKM matrix at…

High Energy Physics - Phenomenology · Physics 2008-11-26 H. González , S. R. Juárez W. , P. Kielanowski , G. López Castro

The observed hierarchy of quark and lepton masses and mixings may be obtained by adding an abelian family symmetry to the Minimal Supersymmetric Model and coupling quarks and leptons to an electroweak singlet scalar field. In a large class…

High Energy Physics - Phenomenology · Physics 2009-10-28 P. Binétruy , S. Lavignac , P. Ramond

We analyse the quark mass hierarchy and CKM matrix using the universal Yukawa coupling model with small violations precisely. We estimate the ranges of the values of 8 violation parameters (delta1u, delta2u, delta3u, delta1d, delta2d,…

High Energy Physics - Phenomenology · Physics 2016-09-06 Tadayuki Teshima , Toyokazu Sakai

A simple ansatz is proposed for neutrino and charged lepton mass matrices, within the framework of universal strength for Yukawa couplings. In this framework all Yukawa couplings have equal moduli and the flavour dependence is only in their…

High Energy Physics - Phenomenology · Physics 2011-03-10 G. C. Branco , M. N. Rebelo , J. I. Silva-Marcos

The evolution of the Cabibbo-Kobayashi-Maskawa matrix and the quark Yukawa couplings is performed for the one-loop renormalization group equations in the universal extra dimension model. It is found that the evolution of mixing angles and…

High Energy Physics - Phenomenology · Physics 2015-03-17 A. S. Cornell , Lu-Xin Liu

We propose a new mass matrix ansatz: At the grand unified (GU) scale, the standard model (SM) Yukawa coupling matrix elements are integer powers of the square root of the GU gauge coupling constant \varepsilon \equiv…

High Energy Physics - Phenomenology · Physics 2014-11-20 Yong-Chao Zhang , De-Hai Zhang

The unification of gauge and Yukawa couplings within the minimal supersymmetric standard model is studied at the two loop level. We derive an expression for the effective scale, $T_{SUSY}$, which characterizes the supersymmetric particle…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Carena , S. Pokorski , C. E. M. Wagner

Within a specific texture of the quark mass matrix the notion of a maximal violation of the $CP$ symmetry can be defined. The experimental constraints from weak decays imply that in reality one is close to the case of maximal $CP$…

High Energy Physics - Phenomenology · Physics 2010-11-01 Harald Fritzsch , Zhi-zong Xing

We propose a universal mixing hypothesis between quark and lepton sectors at high energy scale (probably GUT scale) where quark-lepton universality holds. Namely in the charged lepton diagonal base, all the other mass matrices for up and…

High Energy Physics - Phenomenology · Physics 2013-11-26 Hiroyuki Nishiura , Takeshi Fukuyama

The flavor changing charged currents of the weak sector of the Standard Model are studied in the framework of a quantum statistical approach. The quantum superposition of same-type quarks, generated by the Cabibbo-Kobayashi-Maskawa matrix,…

High Energy Physics - Phenomenology · Physics 2012-06-07 Miguel C. N. Fiolhais

General issues in the renormalization group evolution of fermion masses and mixings is discussed. An effective fixed point in the top quark Yukawa coupling can strongly constrain its value at the electroweak scale. Predictions following…

High Energy Physics - Phenomenology · Physics 2007-05-23 V. Barger , M. S. Berger , P. Ohmann

We study systematically the possibility for realizing realistic values of quark mass ratios $m_c/m_t$ and $m_s/m_b$ and the mixing angle $V_{cb}$ by using only renormalizable Yukawa couplings derived from heterotic orbifold models. We…

High Energy Physics - Phenomenology · Physics 2009-11-10 Pyungwon Ko , Tatsuo Kobayashi , Jae-hyeon Park

We consider the problem of the ordinary charged fermion mass patterns in the framework of a version of the 3-3-1 electroweak gauge model, which includes charged heavy leptons. The masses of the top and the bottom quarks are given at the…

High Energy Physics - Phenomenology · Physics 2009-11-07 M. D. Tonasse
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