Spontaneous CP Violating Phase as The CKM Matrix Phase

We propose that the CP violating phase in the CKM mixing matrix is identical to the CP phases responsible for the spontaneous CP violation in the Higgs potential. A specific multi-Higgs model with Peccei-Quinn (PQ) symmetry is constructed to realize this idea. The CP violating phase does not vanish when all Higgs masses become large. There are flavor changing neutral current (FCNC) interactions mediated by neutral Higgs bosons at the tree level. However, unlike general multi-Higgs models, the FCNC Yukawa couplings are fixed in terms of the quark masses and CKM mixing angles. Implications for meson-anti-meson mixing, including recent data on $D-\bar D$ mixing, and neutron electric dipole moment (EDM) are studied. We find that the neutral Higgs boson masses can be at the order of one hundred GeV. The neutron EDM can be close to the present experimental upper bound.Comment: 16 pages, RevTex. Several typos corrected, and one reference adde

Center or Limit Cycle: Renormalization Group as a Probe

Based on our studies done on two-dimensional autonomous systems, forced non-autonomous systems and time-delayed systems, we propose a unified methodology - that uses renormalization group theory - for finding out existence of periodic solutions in a plethora of nonlinear dynamical systems appearing across disciplines. The technique will be shown to have a non-trivial ability of classifying the solutions into limit cycles and periodic orbits surrounding a center. Moreover, the methodology has a definite advantage over linear stability analysis in analyzing centers

Probing top flavour-changing neutral scalar couplings at the CERN LHC

Top decays into a light Higgs boson and an up or charm quark can reach detectable levels in Standard Model extensions with two Higgs doublets or with new exotic quarks, and in the Minimal Supersymmetric Standard Model. Using both a standard and a neural network analysis we show that the CERN Large Hadron Collider will give 3 sigma evidence of decays with Br(t -> Hc) >= 6.5 10^-5 or set a limit Br(t -> Hc) <= 4.5 10^-5 with a 95% confidence level if these decays are not observed. We also consider limits obtained from single top production associated with a neutral Higgs boson.Comment: Uses elsart.cls. 16 pages, 9 PS figures. Some comments and references added. Final version to appear in PL

Form factors in RQM approaches: constraints from space-time translations

Different relativistic quantum mechanics approaches have recently been used to calculate properties of various systems, form factors in particular. It is known that predictions, which most often rely on a single-particle current approximation, can lead to predictions with a very large range. It was shown that accounting for constraints related to space-time translations could considerably reduce this range. It is shown here that predictions can be made identical for a large range of cases. These ones include the following approaches: instant form, front form, and "point-form" in arbitrary momentum configurations and a dispersion-relation approach which can be considered as the approach which the other ones should converge to. This important result supposes both an implementation of the above constraints and an appropriate single-particle-like current. The change of variables that allows one to establish the equivalence of the approaches is given. Some points are illustrated with numerical results for the ground state of a system consisting of scalar particles.Comment: 37 pages, 7 figures; further comments in ps 16 and 19; further references; modified presentation of some formulas; corrected misprint

Spontaneous CP Violating Phase as the Phase in PMNS Matrix

We study the possibility of identifying the CP violating phases in the PMNS mixing matrix in the lepton sector and also that in the CKM mixing matrix in the quark sector with the phase responsible for the spontaneous CP violation in the Higgs potential, and some implications. Since the phase in the CKM mixing matrix is determined by experimental data, the phase in the lepton sector is therefore also fixed. The mass matrix for neutrinos is constrained leading to constraints on the Jarlskog CP violating parameter $J$, and the effective mass $$ for neutrinoless double beta decay. The Yukawa couplings are also constrained. Different ways of identifying the phases have different predictions for $\mu \to e e\bar e$ and $\tau \to l_1 l_2 \bar l_3$. Future experimental data can be used to distinguish different models.Comment: 16 pages, 3 figure

Hierarchical Neutrino Mass Matrices, CP violation and Leptogenesis

In this work we study examples of hierarchical neutrino mass matrices inspired by family symmetries, compatible with experiments on neutrino oscillations, and for which there is a connection among the low energy CP violation phase associated to neutrino oscillations, the phases appearing in the amplitude of neutrinoless double beta decay, and the phases relevant for leptogenesis. In particular, we determine the predictions from a texture based on an underlying SU(3) family symmetry together with a GUT symmetry, and a strong hierarchy for the masses of the heavy right handed Majorana masses. We also give some examples of inverted hierarchies of neutrino masses, which may be motivated in the context of U(1) family symmetries.Comment: 34 pages. Replaced with published version -typos, corrections and references adde

Possibility of extracting the weak phase γ\gamma from Λb→ΛD0\Lambda_b \to \Lambda D^0 decays

We explore the possibility of extracting the weak phase $\gamma$ from pure tree decays $\Lambda_b \to \Lambda (D^0, \bar{D^0}, D^0_{CP})$ in a model independent way. The CP violating weak phase $\gamma$ can be determined cleanly, without any hadronic uncertainties, as these decay modes are free from the penguin pollutions. Furthermore, neither tagging nor time dependent studies are required to extract the angle $\gamma$ with these modes.Comment: 12 pages, LaTex, Minor changes in the text, version to appear in Phys. Rev.

Protecting the primordial baryon asymmetry in the seesaw model compatible with WMAP and KamLAND

We require that the primordial baryon asymmetry is not washed out in the seesaw model compatible with the recent results of WMAP and the neutrino oscillation experiments including the first results of KamLAND. We find that only the case of the normal neutrino mass hierarchy with an approximate $L_{e}$-symmetry satisfies the requirement. We further derive, depending on the signs of neutrino mass eigenvalues, three types of neutrino mass matrixes, where the values of each element are rather precisely fixed.Comment: 21pages; added reference

Vanishing Effective Mass of the Neutrinoless Double Beta Decay?

We stress that massive neutrinos may be Majorana particles even if the effective mass of the neutrinoless double beta decay m_ee vanishes. We show that current neutrino oscillation data do allow m_ee = 0 to hold, if the Majorana CP-violating phases lie in two specific regions. Strong constraints on three neutrino masses can then be obtained. We find that the neutrino mass spectrum performs a normal hierarchy: m_1 < m_2 < m_3. A possible texture of the neutrino mass matrix is also illustrated under the m_ee = 0 condition.Comment: RevTex 9 pages (2 PS figures included). More discussions and references added. Results partly changed. To appear in Phys. Rev.

'Mu-Tau' symmetry, tribimaximal mixing and four zero neutrino Yukawa textures

Within the type-I seesaw framework with three heavy right chiral neutrinos and in the basis where the latter and the charged leptons are mass diagonal, a near `mu-tau' symmetry in the neutrino sector is strongly suggested by the neutrino oscillation data. There is further evidence for a close to the tribimaximal mixing pattern which subsumes `mu-tau' symmetry. On the other hand, the assumption of a (maximally allowed) four zero texture in the Yukawa coupling matrix Y_nu in the same basis leads to a highly constrained and predictive theoretical scheme. We show that the requirement of an exact `mu-tau' symmetry, coupled with observational constraints, reduces the `seventy two' allowed textures in such a `Y_nu' to 'only four' corresponding to just two different forms of the light neutrino mass matrix `m_nu'. The effect of each of these on measurable quantities can be described, apart from an overall factor of the neutrino mass scale, in terms of two real parameters and a phase angle all of which are within very constrained ranges. The additional input of a tribimaximal mixing reduces these three parameters to `only one' with a very nearly fixed value. Implications for both flavored and unflavored leptogenesis as well as radiative lepton flavor violating decays are discussed. We also investigate the stability of these conclusions under small deviations due to renormalization group running from a high scale where the four zero texture as well as `mu-tau' symmetry or the tribimaximal mixing pattern are imposed.Comment: Typographical changes,accepted for publication in JHE