Joao P. Silva

Generalized CP symmetries and special regions of parameter space in the two-Higgs-doublet model

We consider the impact of imposing generalized CP symmetries on the Higgs sector of the two-Higgs-doublet model, and identify three classes of symmetries. Two of these classes constrain the scalar potential parameters to an exceptional region of parameter space, which respects either a Z{sub 2} discrete flavor symmetry or a U(1) symmetry. We exhibit a basis-invariant quantity that distinguishes between these two possible symmetries. We also show that the consequences of imposing these two classes of CP symmetry can be achieved by combining Higgs family symmetries, and that this is not possible for the usual CP symmetry. We comment on the vacuum structure and on renormalization in the presence of these symmetries. Finally, we demonstrate that the standard CP symmetry can be used to build all the models we identify, including those based on Higgs family symmetries.

Can one detect new physics in I=0 and/or I=2 contributions to the decays B{yields}{pi}{pi}

We study the effects of new-physics contributions to B{yields}{pi}{pi} decays, which can be parametrized as four new complex quantities. A simple analysis is provided by utilizing the reparametrization invariance of the decay amplitudes. We find that six quantities can be reabsorbed into the definitions of Standard Model-like parameters. As a result, the usual isospin analysis provides only two constraints on new physics which are independent of estimates for the Standard Model contributions. In particular, we show that one is not sensitive to new physics affecting the I=0 amplitudes. On the other hand, I=2 new physics can be detected, and its parameters can be measured by using independent determinations of the weak phases. We obtain constraints on these new-physics parameters through a fit to the current experimental data.

Abelian symmetries in the two-Higgs-doublet model with fermions

We classify all possible implementations of an abelian symmetry in the two-Higgs-doublet model with fermions. We identify those symmetries which are consistent with non-vanishing quark masses and a CKM matrix which is not block-diagonal. Our analysis takes us from a plethora of possibilities down to 246 relevant cases, requiring only 34 distinct matrix forms. We show that applying Z_n with n geq 4 to the scalar sector leads to a continuous U(1) symmetry in the whole Lagrangian. Finally, we address the possibilities of spontaneous CP violation and of natural suppression of the flavour changing neutral currents. We explain why our work is relevant even for non-abelian symmetries.

Evading death by vacuum

In the Standard Model, the Higgs potential allows only one minimum at tree level. But the open possibility that there might be two scalar doublets enriches the vacuum structure, allowing for the risk that we might now be in a metastable state, which we dub the panic vacuum. Current experiments at the LHC are probing the Higgs particle predicted as a result of the spontaneous symmetry breaking. Remarkably, in the two Higgs model with a softly broken U(1) symmetry, the LHC experiments already allow to exclude many panic vacuum solutions.

Basis invariant conditions for supersymmetry in the two-Higgs-doublet model

The minimal supersymmetric standard model involves a rather restrictive Higgs potential with two Higgs fields. Recently, the full set of classes of symmetries allowed in the most general two-Higgs-doublet model was identified; these classes do not include the supersymmetric limit as a particular class. Thus, a physically meaningful definition of the supersymmetric limit must involve the interaction of the Higgs sector with other sectors of the theory. Here we show how one can construct basis invariant probes of supersymmetry involving both the Higgs sector and the gaugino-Higgsino-Higgs interactions.

Zeolite-coated ceramic foams for VOCs removal

Abstract Copper (Cu) and Platinum (Pt) based MFI catalysts have been supported on cordierite foams by an improved washcoating method. Uniform catalyst coatings with a mean thickness as low as 27 μm presenting a good adherence onto the foam surface (weight losses of about 0.4±0.05 wt.%) were obtained. With catalyst contents around 8–10 wt.%, these coated-foam catalysts revealed better catalytic behaviours than their bulk-form counterparts for the deep oxidation of isopropanol. Conversions into CO 2 of about 100% are reached for the platinum-coated foam at 160°C.

Decoupling or nondecoupling: Is that the R(

The top quark is well known for the nondecoupling effects it implies in ρ and Rb. The recent experimental Rb data exhibits a disagreement with the SM prediction at more than the 3σ level. It is tempting to explore whether this might be due to nondecoupling New Physics effects, opposite to those of the top. We investigate this issue in the context of models with an extra family of right or left handed, singlet or doublet quarks. It is shown that, contrary to what

b

Petiveria alliacea L. (Phytolaccaceae) is an Amazonian shrub used in traditional medicine for many purposes. This study investigated the genotoxicity of the hydroalcoholic extract of P. alliacea (EHPa). In addition, we conducted pharmacognostic characterization and phytochemical investigation. Phytochemical screening and thin layer chromatography (TLC) were used to determine the chemical composition of the extract. Genotoxicity was evaluated using an in vitro comet assay in human lymphocytes (50, 100, and 250 mg/ml) and an in vivo micronucleus assay in mice orally treated with the extract (50, 100, and 250 mg/kg b.w., p.o.). The phytochemical screening identified the metabolites reducing sugars, alkaloids and saponins. TLC analyses identified organosulfur compounds in EHPa. Comet assay data showed that EHPa induced exacerbated DNA damage at 100 mg/ml treatments (EHPa 100 mg/ml: TL 219.13 ± 48.38 mm, % DNA-t 59.33 ± 18.98%, TM 134.99 ± 61.34, OM 87.48 ± 32.98) as compared with negative control (Roswell Park Memorial Institute (RPMI): TL 37.79 ± 24.79 mm, % DNA-t 9.73 ± 6.56%, TM 4.86 ± 5.79, OM 6.90 ± 5.80; p<0.01). These effects were similar to positive control (hydrogen peroxide). The micronucleus assay, however, showed that EHPa induce slight genotoxicity in vivo. However, EHPa induced an exacerbated DNA damage in vitro, but this effect was slight in the animal model. These in vitro effects may be related to the chemical composition of the extract. n n Key words: Petiveria alliacea, genetic toxicity, DNA damage, comet assay, micronucleus assay.

) question?

The two-Higgs doublet model (2HDM) can have two electroweak breaking, CP-conserving, minima. The possibility arises that the minimum which corresponds to the known elementary particle spectrum is metastable, a possibility we call the panic vacuum. We present analytical bounds on the parameters of the softly broken Peccei-Quinn 2HDM which are necessary and sufficient conditions to avoid this possibility. We also show that, for this particular model, the current LHC data already tell us that we are necessarily in the global minimum of the theory, regardless of any cosmological considerations about the lifetime of the false vacua.