arXiv subjects

E. Díaz

Publications and source records attributed to E. Díaz.

9 recordsLinked to original sources

arXiv2026

Fermion mass hierarchy and flavor signals from a $D_4$ dihedral symmetry within a 2HDM-Tx with four-zero textures

We propose an extended Texturized Two-Higgs Doublet Model (2HDM-Tx) where a discrete $D_4$ symmetry predicts a four-zero texture in the fermion mass matrices. In contrast to the standard ansatz where the underlying Yukawa matrices are assumed to be structurally identical, we introduce a novel configuration of non-equivalent matrices that complementarily generate a specific Hermitian four-zero mass structure. This framework naturally suppresses flavor-changing neutral currents and provides a structural rationale for the fermion mass hierarchy, while in addition including a dark matter candidate. As a concrete phenomenological application, we show that the model simultaneously accommodates the persistent neutral resonance excesses at $95\text{ GeV}$ and $152\text{ GeV}$, satisfies current \text{LHC} Higgs data, and is consistent with the stringent upper bounds from lepton flavor violation processes. These combined constraints severely restrict the parameter space of the scalar phenomenology. Finally, we study the prospects for the discovery of the lepton-flavor violating process $h \to τμ$ at the High-Luminosity LHC.

hep-ph↗

arXiv2023

The Multipurpose Interferometric Array and the development of its technological demonstrator

We present a proposal for the construction and development of a new instrument for radio astronomical observations based on interferometric techniques, that will provide high angular resolution in the 21 cm band, with the intention of improving and extending the current performance of the instruments used at the Argentine Institute of Radio Astronomy. This will allow internationally competitive scientific research and the acquisition of cutting-edge scientific and technological know-how in the aforementioned techniques, enabling interferometric measurements and the development of very long baseline or VLBI techniques. This project is called MIA, an acronym for "Multipurpose Interferometric Array".

astro-ph.IM↗

arXiv2019

Sigmoidal Inflation

In this paper we present a new cosmological inflationary model which is constructed using the Ivanov-Salopek-Bond method with a logistic generating function. We derive the inflationary observables as well as the duration and temperature of the subsequent reheating epoch of our model exactly, with no need to recur to the slow roll approximation. The obtained scalar spectral index and tensor-to-scalar ratio of perturbations fall comfortably within the range of the measurements presented by the Planck collaboration. On the other hand, for the reheating era, our model predicts a relatively small number of e-folds and thus high temperatures, still within range of Planck's bounds.

hep-ph↗

arXiv2017

$τ^{-}\to \ell_i^{-} \ell_i^{+} \ell_j^{-} \barν_{j} ν_τ$ decays with a magnetic dipole term

Using the massive helicity formalism we calculate the five-body average square amplitude of the decays $τ^{-}\to \ell_i^{-} \ell_i^{+} \ell_j^{-} \barν_{j} ν_τ$ $(\ell=e,\,μ)$ within the Standard Model (SM), we then introduce a dimension-five effective vertex $Γ^{ττγ}$ in order to determine the feasibility of imposing limits on the tau anomalous magnetic dipole moment ($a_τ$) via the current or future experimental measurements of the branching ratio for the decay $τ^{-}\to e^{-} e^{+} e^{-} \barν_{e} ν_τ$.

hep-ph↗

arXiv2014

Spin-dependent THz oscillator based on hybrid graphene superlattices

We theoretically study the occurrence of Bloch oscillations in biased hybrid graphene systems with spin-dependent superlattices. The spin-dependent potential is realized by a set of ferromagnetic insulator strips deposited on top of a gapped graphene nanoribbon, which induce a proximity exchange splitting of the electronic states in the graphene monolayer. We numerically solve the Dirac equation and study Bloch oscillations in the lowest conduction band of the spin-dependent superlattice. While the Bloch frequency is the same for both spins, we find the Bloch amplitude to be spin dependent. This difference results in a spin-polarized ac electric current in the THz range.

cond-mat.mes-hall↗

arXiv2014

Contact effects in spin transport along double-helical molecules

We report on spin transport along double-helical molecular systems by considering various contact configurations and asymmetries between the two helical strands in the regime of completely coherent charge transport. Our results reveal that no spin polarization appears in two-terminal molecular devices when coupled to one-dimensional electrodes. The same holds in the case of finite-width electrodes if there is a \emph{bottleneck} of one single site in the system electrode--molecule--electrode. Then, additional dephasing is necessary to induce spin-filtering effects. In contrast, nonzero spin polarization is found in molecular devices with multiple terminals or with two finite-width electrodes, each of them connected to more than one site of the molecule. Then, the magnitude of spin polarization can be enhanced by increasing the asymmetry between the two strands. We point out that the spin-filtering effects could emerge in double-helical molecular devices at low temperature without dephasing by a proper choice of the electrode number and the connection between the molecule and the electrodes.

cond-mat.mes-hall↗

arXiv2011

Super Bloch oscillations in the Peyrard-Bishop-Holstein model

Recently, polarons in the Peyrard-Bishop-Holstein model under DC electric fields were established to perform Bloch oscillations, provided the charge-lattice coupling is not large. In this work, we study this model when the charge is subjected to an applied field with both DC and AC components. Similarly to what happens in the rigid lattice, we find that the carrier undergoes a directed motion or coherent oscillations when the AC field is resonant or detuned with respect to the Bloch frequency, respectively. The electric density current and its Fourier spectrum are also studied to reveal the frequencies involved in the polaron dynamics.

cond-mat.mes-hall↗

arXiv2011

Slow light in molecular aggregates nanofilms

We study slow light performance of molecular aggregates arranged in nanofilms by means of coherent population oscillations (CPO). The molecular cooperative behavior inside the aggregate enhances the delay of input signals in the GHz range in comparison with other CPO-based devices. Moreover, the problem of residual absorption present in CPO processes, is removed. We also propose an optical switch between different delays by exploiting the optical bistability of these aggregates.

physics.optics↗

arXiv2008

Intraband exciton relaxation in a biased lattice with long-range correlated disorder

We study numerically the intraband exciton relaxation in a one-dimensional lattice with scale-free disorder, in the presence of a linear bias. Exciton transport is considered as incoherent hoppings over the eigenstates of the static lattice. The site potential of the unbiased lattice is long-range-correlated with a power-law spectral density $S(k) \sim 1/k^α$, $α> 0$. The lattice supports a phase of extended states at the center of the band, provided $α$ is larger than a critical value $α_c$ [F. A. B. F. de Moura and M. L. Lyra, Phys. Rev. Lett. \textbf{81}, 3735 (1998)]. When the bias is applied, the absorption spectrum displays clear signatures of the Wannier-Stark ladder [E. D\'ıaz \emph{et al.}, Phys. Rev. B\textbf{73}, 172410 (2006)]. We demonstrate that in unbiased lattices and in weakly correlated potentials the decay law is non-exponential. However, the decay is purely exponential when the bias increases and $α$ is large. We relate this exponential decay to the occurrence of the Wannier-Stark ladder in the exciton band.

cond-mat.dis-nn↗