Lepton Flavor Violation in the Two Higgs Doublet Model type III

We consider the Two Higgs Doublet Model (2HDM) of type III which leads to Flavour Changing Neutral Currents (FCNC) at tree level in the leptonic sector. In the framework of this model we can have, in principle, two situations: the case (a) when both doublets acquire a vacuum expectation value different from zero and the case (b) when only one of them is not zero. In addition, we show that we can make two types of rotations for the flavor mixing matrices which generates four types of lagrangians, with the rotation of type I we recover the case (b) from the case (a) in the limit $\tan \beta \to \infty$, and with the rotation of type II we obtain the case (b) from (a) in the limit $\tan \beta \to 0.$Moreover, two of the four possible lagrangians correspond to the models of types I and II plus Flavor Changing (FC) interactions. The analitical expressions of the partial lepton number violating widths $\Gamma (\mu \to eee)$ and $\Gamma (\mu \to e\gamma)$are derived for the cases (a) and (b) and both types of rotations.$$In all cases these widths go asymptotically to zero in the decoupling limit for all Higgses. We present from our analysis upper bounds for the flavour changing transition $\mu \to e,$ and we show that such bounds are sensitive to the VEV structure and the type of rotation utilized.Comment: 7 pages RevTeX4, 4 figures postscript, new section added and some new reference

Polarized Single Top Production at Leptonic Colliders from Broken R Parity Interactions Incorporating CP Violation

The contribution from the R parity violating interactions in the associated production of a top quark with a charm antiquark is examined for high energy leptonic colliders. We concentrate on the reactions associated with the semileptonic top decay. A set of characteristic dynamical distributions for the signal events is evaluated and the results contrasted against those from the standard model W-boson pair production background. Next, we turn to a study of a CP-odd observable, associated with the top spin, which leads to an asymmetry in the energy distribution of the emitted charged leptons for the pair of CP-conjugate final states, $b \bar l \nu \bar c$ and $\bar b l \bar \nu c$. A non vanishing asymmetry arises from a CP-odd phase, embedded in the R parity violating coupling constants, through interference terms between the R parity violating amplitudes at both the tree and loop levels.Comment: revtex file. 17 pages. 7 postscript figures. 1 table. The revised version includes an estimate of experimental uncertainties. Submitted to Phys. Rev.

Texture of Yukawa coupling matrices in general two-Higgs-doublet model

We discuss possible parallel textures of the Yukawa coupling matrices in the generaltwo-Higgs-doublet model (2HDM). In those textures the flavor changing neutral currentsare naturally suppressed. Motivated by a phenomenologically successful texturewith four texture zeros in the standard model, we propose a predictive ansatz for the Yukawa coupling matrices with the same texture in the general 2HDM. Compared with the six texture-zero based ansatz proposed by Cheng and Sher, it is in a better agreement with the data of quark mixings and CP violation. The four texture-zero based ansatz predicts a different hierarchy in the Yukawa coupling matrix elements. As a consequence, in the lepton sector, the related Yukawa couplings are less constrained by the experimental upper bound of $\mu\to e\gamma$, which allows significantly larger predictions for other processes. The contributions from neutral scalar interactions to the lepton number violation decay modes $\ell\to \ell_{1}\ell_{2}\ell_{3}$ are calculated in both ansatz. It is shown that the predictions from the four texture-zero based ansatz could be two order of magnitude greater than that from the six texture-zero based one. The branching ratio of $\mu\to 3e$ and $\tau\to 3\mu$ can reach $7.5 \times 10^{-17}$ and 1.3\tiems 10^{-10} respectively. The predicted ratio of $Br(\mu\to 3e)/Br(\tau\to 3e)$ is also larger and almost parameter independent. Those differences make the two ansatz to be easily distinguished by the future experiments.Comment: 12 pages, 2 figure

Top-Charm Associated Production in High Energy e+e−e^+e^- Collisions

The possibility of exploring the flavor changing neutral current $tcZ/tc\gamma$ couplings in the production vertex for the reaction \epem\to t\bar c + \bar tc is examined. Using a model independent parameterization for the effective Lagrangian to describe the most general three-point interactions, production cross sections are found to be relatively small at LEP II, but potentially sizeable at higher energy \epem colliders. The kinematic characteristics of the signal are studied and a set of cuts are devised for clean separation of the signal from background. The resulting sensitivity to anomalous flavor changing couplings at LEP II with an integrated luminosity of $4\times 500$ pb$^{-1}$ is found to be comparable to their present indirect constraints from loop processes, while at higher energy colliders with $0.5-1$ TeV center-of-mass energy and 50-200 fb$^{-1}$ luminosity, one expects to reach a sensitivity at or below the percentage level.Comment: Latex, 22 page

Search for anomalous top-gluon couplings at LHC revisited

Through top-quark pair productions at LHC, we study possible effects of nonstandard top-gluon couplings yielded by SU(3)xSU(2)xU(1) invariant dimension-6 effective operators. We calculate the total cross section and also some distributions for p p -> t tbar X as functions of two anomalous-coupling parameters, i.e., the chromoelectric and chromomagnetic moments of the top, which are constrained by the total cross section sigma(p pbar -> t tbar X) measured at Tevatron. We find that LHC might give us some chances to observe sizable effects induced by those new couplings.Comment: One comment and related two refs. added. Final version (to appear in Eur.Phys.J. C

Pillared two-dimensional metal-organic frameworks based on a lower-rim acid appended calix[4]arene

Solvothermal reactions of the lower-rim functionalized diacid calix[4]arene 25,27-bis(methoxycarboxylic acid)-26,28-dihydroxy-4-tert-butylcalix[4]arene (LH₂) with Zn(NO₃)₂•6H₂O and the dipyridyl ligands 4,4/-bipyridyl (4,4/-bipy), 1,2-di(4-pyridyl)ethylene (DPE) or 4,4/-azopyridyl (4,4/-azopy) afforded a series of 2-D structures of the formulae {[Zn(4,4/-bipy)(L)]•2¼DEF}n (1), {[Zn₂(L)(DPE)]•DEF}n (2) and {[Zn(OH₂)₂(L)(4,4/-azopy)]•DEF}n (3) (DEF = diethylformamide)

Large Tree Level CP Violation in e+e−→ttˉH0e^+e^-\to t\bar{t}H^0 in The Two Higgs Doublet Model

We find a large CP violation effect within the Two-Higgs-Doublet-Model for the reaction $e^+e^-\to t\bar{t}H^0$ at future linear colliders. The CP-asymmetry arises already at the tree level as a result of interference between diagrams with $H^0$ emission from $t$ (and $\bar{t}$) and its emission from a $Z^0$ and can be about 10--20\%. In the best case one needs a few hundred $t\bar{t}H^0$ events to observe CP violation at the 3$\sigma$ level.Comment: UU encoded tar compressed tex file with postscript figure

Heavy quark polarizations of e+e−→qqˉhe^+e^-\to q \bar q h in the general two Higgs doublet model

The polarizations of the heavy quark ($q=t$ or $b$) in the process $e^+e^- \to q \bar q h$ have been calculated in the general two Higgs doublet model. The CP violating normal polarization of the top quark can reach 8%, and $2 \sim 3$ for the bottom quark, while it is zero in the standard model. The longitudinal and transverse polarizations of the bottom quark can be significantly different from those in SM and consequently could aslo be used as the probe of the new physics.Comment: 12 pages, discussion on statistic significance added, version to appear in PR

Three heavy jet events at hadron colliders as a sensitive probe of the Higgs sector

Assuming that a non-standard neutral Higgs with an enhanced Yukawa coupling to a bottom quark is observed at future hadron experiments, we propose a method for a better understanding of the Higgs sector. Our procedure is based on "counting" the number of events with heavy jets (where "heavy" stands for a c or b jet) versus b jets, in the final state of processes in which the Higgs is produced in association with a single high p_T c or b jet. We show that an observed signal of the type proposed, at either the Tevatron or the LHC, will rule out the popular two Higgs doublet model of type II as well as its supersymmetric version - the Minimal Supersymmetric Standard Model (MSSM), and may provide new evidence in favor of some more exotic multi Higgs scenarios. As an example, we show that in a version of a two Higgs doublet model which naturally accounts for the large mass of the top quark, our signal can be easily detected at the LHC within that framework. We also find that such a signal may be observable at the upgraded Tevatron RunIII, if the neutral Higgs in this model has a mass around 100 GeV and \tan\beta > 50 and if the efficiency for distinguishing a c jet from a light jet will reach the level of 50%.Comment: Revtex, 11 pages, 4 figures embedded in the text. Main changes with respect to Version 1: Numerical results re-calculated using the CTEQ5L pdf, improved discussion on the experimental consequences, new references added. Conclusions remain unchanged. As will appear in Phys. Rev.