Four-neutrino oscillations at SNO

We discuss the potential of the Sudbury Neutrino Observatory (SNO) to constrain the four-neutrino mixing schemes favored by the results of all neutrino oscillations experiments. These schemes allow simultaneous transitions of solar {\ensuremath{\nu}}_{e}'s into active {\ensuremath{\nu}}_{\ensuremath{\mu}}'s, {\ensuremath{\nu}}_{\ensuremath{\tau}}'s, and sterile {\ensuremath{\nu}}_{s} controlled by the additional parameter {\mathrm{cos}}^{2}({\ensuremath{\vartheta}}_{23}){\mathrm{cos}}^{2}({\ensuremath{\vartheta}}_{24}) and they contain as limiting cases the pure {\ensuremath{\nu}}_{e}-active and {\ensuremath{\nu}}_{e}-sterile neutrino oscillations. We first obtain the solutions allowed by the existing data in the framework of the BBP00 standard solar model and quantify the corresponding predictions for the charged current and the neutral current to charged current (NC/CC) event ratios at SNO in the different allowed regions as a function of the active-sterile admixture. Our results show that some information on the value of {\mathrm{cos}}^{2}({\ensuremath{\vartheta}}_{23}){\mathrm{cos}}^{2}({\ensuremath{\vartheta}}_{24}) can be obtained by the first SNO measurement of the CC ratio, while considerable improvement on the knowledge of this mixing will be achievable after the measurement of the NC/CC ratio

The complete HEFT Lagragian after the LHC Run I

The complete effective chiral Lagrangian for a dynamical Higgs is presented and constrained by means of a global analysis including electroweak precision data together with Higgs and triple gauge-boson coupling data from the LHC Run I. The operators' basis up to next-to-leading order in the expansion consists of 148 (188 considering right-handed neutrinos) flavour universal terms and it is presented here making explicit the custodial nature of the operators. This effective Lagrangian provides the most general description of the physical Higgs couplings once the electroweak symmetry is assumed, and it allows for deviations from the SU(2)L doublet nature of the Standard Model Higgs. The comparison with the effective linear Lagrangian constructed with an exact SU(2)L doublet Higgs and considering operators with at most canonical dimension six is presented. A promising strategy to disentangle the two descriptions consists in analysing (i) anomalous signals present only in the chiral Lagrangian and not expected in the linear one, that are potentially relevant for LHC searches, and (ii) decorrelation effects between observables that are predicted to be correlated in the linear case and not in the chiral one. The global analysis presented here, which includes several kinematic distributions, is crucial for reducing the allowed parameter space and for controlling the correlations between parameters. This improves previous studies aimed at investigating the Higgs Nature and the origin of the electroweak symmetry breaking

Solar and atmospheric four-neutrino oscillations

We present an analysis of the neutrino oscillation solutions of the solar and atmospheric neutrino problems in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones and the mass spectra presents two separated doublets. Such scenarios allow for simultaneous transitions of solar $\nu_e$, as well as atmospheric $\nu_\mu$, into active and sterile neutrinos controlled by the additional mixing angles $\vartheta_{23}$ and $\vartheta_{24}$, and they contain as limiting cases the pure solar $\nu_e$-active and $\nu_e$-sterile neutrino oscillations, and the pure atmospheric $\nu_\mu\to\nu_s$ and $\nu_\mu\to\nu_\tau$ oscillations, respectively. We evaluate the allowed active-sterile admixture in both solar and atmospheric oscillations from the combined analysis. Our results show that, although the Super-Kamiokande data disfavour both the pure $\nu_\mu\to\nu_s$ atmospheric channel and the pure $\nu_e\to\nu_s$ solar channel, the result from the combined analysis still favours close-to-pure active and sterile oscillations and disfavours oscillations into a near-maximal active-sterile admixture

Anomalous couplings of the third generation in rare B Decays

We study the potential effect of anomalous couplings of the third generation quarks to gauge bosons in rare B decays. We focus on the constraints from flavor changing neutral current processes such as $b\to s\gamma$ and $b\to s \ell^+\ell^-$. We consider both dimension-four and dimension-five operators and show that the latter can give large deviations from the standard model in the still unobserved dilepton modes, even after the bounds from $b\to s\gamma$ and precision electroweak observables are taken into account

New Higgs couplings at e^+ e^- and hadronic colliders

We examine the potentiality of both CERN LEP and Fermilab Tevatron colliders to establish bounds on new couplings involving the bosonic sector of the standard model. We pay particular attention to the anomalous Higgs interactions with $\gamma$, $W^{\pm}$ and $Z^0$. A combined exclusion plot for the coefficients of different anomalous operators is presented. The sensitivity that can be achieved at the Next Linear Collider and at the upgraded Tevatron is briefly discussed

Zenith angle distributions at Super-Kamiokande and SNO and the solution of the solar neutrino problem

We have performed a detailed study of the zenith angle dependence of the regeneration factor and distributions of events at SNO and SK for different solutions of the solar neutrino problem. In particular, we discuss the oscillatory behavior and the synchronization effect in the distribution for the LMA solution, the parametric peak for the LOW solution, etc. A physical interpretation of the effects is given. We suggest a new binning of events which emphasizes the distinctive features of the zenith angle distributions for the different solutions. We also find the correlations between the integrated day-night asymmetry and the rates of events in different zenith angle bins. The study of these correlations strengthens the identification power of the analysis

Global analyses of neutrino oscillation experiments

We summarize the determination of some neutrino properties from the global analysis of solar, atmospheric, reactor, and accelerator neutrino data in the framework of three-neutrino mixing as well as in some extended scenarios such as the mixing with eV-scale sterile neutrinos invoked for the interpretation of the short baseline anomalies, and the presence of non-standard neutrino interactions

Robust determination of the Higgs couplings: Power to the data

We study the indirect effects of new physics on the phenomenology of the recently discovered "Higgs-like" particle. In a model-independent framework these effects can be parametrized in terms of an effective Lagrangian at the electroweak scale. In a theory in which the S U ( 2 ) L × U ( 1 ) Y gauge symmetry is linearly realized they appear at lowest order as dimension-six operators, containing all the standard model fields including the light scalar doublet, with unknown coefficients. We discuss the choice of operator basis which allows us to make better use of all the available data to determine the coefficients of the new operators. We illustrate our present knowledge of those by performing a global five-parameter fit to the existing data which allows simultaneous determination of the Higgs couplings to gluons, electroweak gauge bosons, bottom quarks, and tau leptons. We find that for all scenarios considered the standard model predictions for each individual Higgs coupling and observable are within the corresponding 90% C.L. allowed range, the only exception being the Higgs branching ratio into two photons for the scenario with standard couplings of the Higgs to fermions. We finish by commenting on the implications of the results for unitarity of processes at higher energies

Constraining anomalous Higgs boson interactions

The recently announced Higgs boson discovery marks the dawn of the direct probing of the electroweak symmetry breaking sector. Sorting out the dynamics responsible for electroweak symmetry breaking now requires probing the Higgs boson interactions and searching for additional states connected to this sector. In this work, we analyze the constraints on Higgs boson couplings to the standard model gauge bosons using the available data from Tevatron and LHC. We work in a model-independent framework expressing the departure of the Higgs boson couplings to gauge bosons by dimension-six operators. This allows for independent modifications of its couplings to gluons, photons, and weak gauge bosons while still preserving the Standard Model (SM) gauge invariance. Our results indicate that best overall agreement with data is obtained if the cross section of Higgs boson production via gluon fusion is suppressed with respect to its SM value and the Higgs boson branching ratio into two photons is enhanced, while keeping the production and decays associated to couplings to weak gauge bosons close to their SM prediction

Determining Triple Gauge Boson Couplings from Higgs Data

In the framework of effective Lagrangians with the S U ( 2 ) L × U ( 1 ) Y symmetry linearly realized, modifications of the couplings of the Higgs field to the electroweak gauge bosons are related to anomalous triple gauge couplings (TGCs). Here, we show that the analysis of the latest Higgs boson production data at the LHC and Tevatron give rise to strong bounds on TGCs that are complementary to those from direct TGC analysis. We present the constraints on TGCs obtained by combining all available data on direct TGC studies and on Higgs production analysis