Search results for "unitarity"
showing 5 items of 245 documents
Charge fluctuations and electric mass in a hot meson gas
2006
Net-Charge fluctuations in a hadron gas are studied using an effective hadronic interaction. The emphasis of this work is to investigate the corrections of hadronic interactions to the charge fluctuations of a non-interacting resonance gas. Several methods, such as loop, density and virial expansions are employed. The calculations are also extended to SU(3) and some resummation schemes are considered. Although the various corrections are sizable individually, they cancel to a large extent. As a consequence we find that charge fluctuations are rather well described by the free resonance gas.
Phenomenology of non-standard neutrino interactions
2016
Today neutrino physics is in a privileged position within the fascinating field of particle physics. From the discovery of neutrino oscillations by Super-Kamiokande in 1998, the door to physics beyond the Standard Model (SM in what follows) has been opened. This fact implies that neutrinos have to be massive in opposition to the Standard Model assumption. However, this is not a surprise completely, but it was already hinted from theoretical and experimental observations in the two decades prior to the discovery of the oscillatory phenomenon, as neutrino masses included in unification models or the observed deficit of the atmospheric and solar neutrino fluxes. As a consequence of this new pa…
Testing the nature of the Λ(1520)-resonance in proton-induced production
2006
The $\Lambda(1520)$ resonance has been recently studied in a unitarized coupled channel formalism with $\pi\Sigma(1385)$, $K\Xi(1530)$, $\bar{K}N$ and $\pi\Sigma$ as constituents blocks. We provide a theoretical study of the predictions of this model in physical observables of the $pp\to pK^+K^-p$ and $pp\to pK^+\pi^0\pi^0\Lambda$ reactions. In particular, we show that the ratio between the $\pi^0\pi^0\Lambda$ and $K^-p$ mass distributions can provide valuable information on the ratio of the couplings of the $\Lambda(1520)$ resonance to $\pi\Sigma(1385)$ and $\bar{K}N$ that the theory predicts. Calculations are done for energies which are accessible in an experimental facility like COSY at …
Stronger C -odd color charge correlations in the proton at higher energy
2023
The non-forward eikonal scattering matrix for dipole-proton scattering at high energy obtains an imaginary part due to a $C$-odd three gluon exchange. We present numerical estimates for the perturbative Odderon amplitude as a function of dipole size, impact parameter, their relative azimuthal angle, and light-cone momentum cutoff $x$. The proton is approximated as $\psi_\mathrm{qqq}|qqq\rangle + \psi_\mathrm{qqqg}|qqqg\rangle$, where $\psi_\mathrm{qqq}$ is a non-perturbative three quark model wave function while the gluon emission is computed in light-cone perturbation theory. We find that the Odderon amplitude increases as $x$ decreases from 0.1 to 0.01. At yet lower $x$, the reversal of t…
Role of the N-*(1535) in the J/psi -> pp and J/psi -> p(+)Lambda reactions
2009
We study the J/psi -> p eta p and J/psi -> pK(+)Lambda reactions with a unitary chiral approach. We find that the unitary chiral approach, which generates the N-*(1535) dynamically, can describe the data reasonably well, particularly the ratio of the integrated cross sections. This study provides further support for the unitary chiral description of the N-*(1535). We also discuss some subtle differences between the coupling constants determined from the unitary chiral approach and those determined from phenomenological studies