相关论文: Dramatic implications of unitarity for meson spect…
Recently the CDF Collaboration has announced a new precise measurement of the $W$-boson mass $M_W$ that deviates from the Standard Model (SM) prediction by $7\sigma$. The discrepancy in $M_W$ is about $\Delta_W\simeq70$ MeV and probably…
A diboson excess has been observed ---albeit with very limited statistical significance--- in $WW$, $WZ$ and $ZZ$ final states at the LHC experiments using the accumulated 8 TeV data. Assuming that these signals are due to resonances…
The CDF collaboration has recently published a precision measurement of the W-boson mass that differs from the Standard Model prediction by seven standard deviations. This result can be explained with additional electroweak multiplets that…
The full complex phase structure of the meson-baryon reaction amplitude in coupled channels approach is investigated, including also the photon-baryon channel. The result may be viewed as a generalization of the well-known Watson's theorem.…
Branching ratios for the decay of hadrons with large width or near thresholds depend on their definition. We test different definitions and show that rather different branching ratios can be obtained. For wide resonances and for sequential…
A unitary multi-channel approach, first developed by the Carnegie-Mellon- Berkeley group, is applied to extract the pole positions, masses, and partial decay widths of nucleon resonances. Input used are the partial wave amplitudes for the…
Broad resonances challenge the standard Monte-Carlo treatment of unstable particles, which introduces a Breit-Wigner width into leading-order matrix elements and can generate unphysical gauge artifacts. We develop a gauge-consistent…
Extensions of the Standard Model are required to give mass to the light neutrinos and explain neutrino oscillations. One of the simplest ideas is to introduce new heavy, gauge singlet fermions that play the role of right-handed neutrinos in…
If the Electroweak Symmetry Breaking Sector turns out to be strongly interacting, the actively investigated effective theory for longitudinal gauge bosons plus Higgs can be efficiently extended to cover the regime of saturation of unitarity…
In the presence of mixing between massive neutrino states, the distortion of the electron spectrum in beta decay is, in general, a function of several masses and mixing angles. For $3\nu$-schemes which describe the solar and atmospheric…
Recent calculations have significantly decreased the scheme and residual scale dependence of basic radiative corrections of the Standard Electroweak Model. This leads to a theoretically accurate prediction of the W-boson mass M(W), as well…
We study the scattering of longitudinally polarized W bosons in extensions of the Standard Model where anomalous Higgs couplings to gauge sector and higher order O(p^4) operators are considered. These new couplings with respect to the…
The available data on the a0(980), f0(980), f0(1300) and K*0(1430) mesons are fitted as a distorted 0++ nonet using only 6 parameters and a very general model. This includes all light two-pseudoscalar thresholds, constraints from Adler…
It has been confirmed experimentally the existence of a mass gap between Standard Model (SM) and eventual Beyond Standard Model (BSM) fields. Therefore, the use of effective approaches to search for fingerprints of New Physics is very…
We analyze $\pi\pi-K\bar{K}$ and $\pi\eta-K\bar{K}$ couple channel [1,1] matrix Pad\'e amplitudes of $SU(3)\times SU(3)$ chiral perturbation theory. By fitting phase shift and inelasticity data, we determine pole positions in different…
By introducing three right-handed neutrino singlets, the popular canonical seesaw mechanism is able to simultaneously explain the tiny masses of Majorana neutrinos and the baryon asymmetry of the Universe. In this paper, we provide an…
Neutrino oscillations are well established and the relevant parameters determined with good precision, except for the CP phase, in terms of a unitary lepton mixing matrix. Seesaw extensions of the Standard Model predict unitarity deviations…
It is shown from a very general model and an analysis of data on the lightest 0++ meson nonet that the f0(980) and f0(1200) resonance poles are two manifestations of the same ss state. Similarily the a0(980) and the a0(1450) are likely to…
Properties of scalar-isoscalar mesons are analysed using separable interactions in three decay channels: pion-pion, kaon-antikaon and an effective 2pion-2pion. We obtain different solutions by fitting various data on the pion-pion and…
We consider the production and scattering amplitudes of heavy mesons in a situation, where there are two closely spaced narrow resonances, which structure we refer to as a diresonance. Assuming strong overlapping of the resonances coupled…