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Hydrogen is one of the most promising candidates for clean energy production. Photoelectrochemical devices look promising for the decomposition of the water molecule into 2H$_2$ + O$_2$. Oxynitrides, like the solid solution Sr$_{1-x}$Ca$_x$O$_2$N, are good candidates due to the low band gap that lies into the maximum zone of the solar radiation spectrum. A necessary condition for the photoelectrochemical process to work without a bias voltage is that the minimum of the semiconductor conduction band must be more positive than the reduction potential H$^+$ to H$_2$, whereas the maximum of the semiconductor valence band must be more negative than the oxidation potential of H$_2$O to O$_2$. Thus, band alignment studies in interfaces of semiconductors with water become of great importance. They present several subtleties, as different or simplistic modelling will result in few decimes of eV difference that would lead to a wrong prediction in the alignment. So, to find a trustful method is desirable. In this work, first principles calculations based on density functional theory (DFT) in the all electron and the pseudopotential approaches have been performed for the analysis of the band alignment in Sr$_{1-x}$Ca$_x$O$_2$N /H$_2$O interfaces. A detailed study of the modelling of the surface, supercells, and interface with water molecules was done. Experimental data were taken for the structures and photoelectrochemical behaviour and well reproduced by the methodology implemented. The analysis carried out led to theoretical results compatible with the experimental results: the calculations show that the Sr$_{1-x}$Ca$_x$O$_2$N /H$_2$O is suitable for photoelectrochemical applications, and the partial substitution of Sr by Ca enables the gap and alignment tuning thus enhancing the complex performance.

Let $A \in \mathbb{R}^{n \times (n - d)}$ be a random matrix with independent uniformly anti-concentrated entries satisfying $\mathbb{E}\lvert A\rvert_{HS}^2 \leq Kn(n-d)$ and let $H$ be the subspace spanned by $H$. Let $X \in \mathbb{R}^n$ be a random vector with uniformly anti-concentrated entries. We show that when $1 \leq d \leq \lambda n/\log n$ the distance between between $X$ and $H$ satisfies the following following small ball probability estimate: \[ \Pr\left( \text{dis}(X,H) \leq t\sqrt{d} \right) \leq (Ct)^{d} + e^{-cn}, \] for some constants $\lambda,c,C > 0$. This extends the distance theorems of Rudelson and Vershynin, Livshyts, and Livshyts,Tikhomirov, and Vershynin by dropping any identical distribution assumptions about the entries of $X$ and $A$. Furthermore it can be applied to prove numerous results about random matrices in the inhomogenous setting. These include lower tail estimates on the smallest singular value of rectangular matrices and upper tail estimates on the smallest singular value of square matrices. To obtain a distance theorem for inhomogenous rectangular matrices we introduce a new tool for this new general ensemble of random matrices, Randomized Logarithmic LCD, a natural combination of the Randomized LCD, used in study of smallest singular values of inhomogenous square matrices, and of the Logarithmic LCD, used in the study of no-gaps delocalization of eigenvectors and the smallest singular values of Hermitian random matrices.

Generalized parton distributions (GPDs) are off-forward matrix elements of quark and gluon operators that work as a window to the total angular momentum of partons and their transverse imaging (nucleon tomography). To access GPDs one needs to look into exclusive processes which are usually studied in a kinematic regime known as the Bj\"orken limit. In this limit, the photon virtualities are much larger than the hadron mass $M$, and the kick to the hadron measured by the Mandelstam's variable $t$. It turns out that this is not enough for the purposes of a precise GPD extraction and, in particular, of nucleon tomography for which measurements in a sizable range of $t$ are required. Deviation with respect to the Bj\"orken limit induces kinematic higher-twist corrections which enter the amplitudes with powers of $|t|/\mathbb{Q}^2$ and $M^2/\mathbb{Q}^2$, where $\mathbb{Q}^2$ denotes the scale of the process (basically, the sum of photon virtualities in the case of DDVCS). There are also corrections by the name of "genuine" higher twists which are a separate topic and are not the subject of this research study. In this manuscript, we present novel calculations of DDVCS amplitudes off a (pseudo-)scalar target including up to kinematic twist-4 corrections. These results are important for measuring DDVCS, DVCS and TCS through the Sullivan process and off helium-4 target at the future Electron-Ion Collider (EIC) and JLab experiments. Preliminary numerical estimates for the pion target are provided., Comment: 5 pages, 2 figures, conference proceedings for the 31st International Workshop on Deep Inelastic Scattering (DIS2024)

The upcoming generation of telescopes, instruments, and surveys is poised to usher in an unprecedented "Big Data" era in the field of astronomy. Within this context, even seemingly modest tasks such as spectral line analyses could become increasingly challenging for astronomers. In this paper, we announce the release of ${\rm L{\small I}M{\small E}}$. This package is tailored for multidisciplinary observations with long-slit and integral field spectroscopy (IFS) support. ${\rm L{\small I}M{\small E}}$ functions encompass the reading of observational files, detecting lines, conditioned line fitting, and the plotting and storage of results. Most importantly, these measurements are structured to support the subsequent chemical and kinematic analyses. To reduce the coding effort required from users, we introduced a notation system for atomic transitions that is accessible to humans and machine-readable. Along with this system, we present an extensive database of line bands, spanning from the ultraviolet to the infrared wavelength range. Additionally, we propose a model designed to train machine learning algorithms in line detection. ${\rm L{\small I}M{\small E}}$ features a comprehensive online documentation, which details the command attributes and includes several tutorials. These tutorials range from measuring a single line to analyzing an entire IFS data cube. This library functions and measurements are showcased in an online virtual observatory. The data in this interactive website come from the JWST NIRSpec observations of the CEERs survey. In this regard, ${\rm L{\small I}M{\small E}}$ offers improvements related to the dissemination and accessibility of astronomical spectra., Comment: Accepted for publication in A&A

The ultraviolet continuum traces young stars while the near-infrared unveils older stellar populations and dust-obscured regions. Balmer emission lines provide insights on gas properties and young stellar objects but are highly affected by dust attenuation. The near-infrared Paschen lines suffer less dust attenuation and can be used to measure star formation rates (SFRs) in star-forming regions obscured by dust clouds. We select 13 sources between redshifts 1 and 3 observed with HST, JWST/NIRCam and NIRSpec based on the availability of at least one Balmer and one Paschen line with S/N > 5. With a newly-developed version of CIGALE, we fit their hydrogen line equivalent widths (EWs) and photometric data. We assess the impacts of the removal of spectroscopic data by comparing the quality of the fits of the spectro-photometric data to those with photometric data only. We compare the single (BC03) vs binary (BPASS) stellar populations models in the fitting process of spectro-photometric data. We derive the differential attenuation and explore different attenuation recipes by fitting spectro-photometric data with BC03. For each stellar model and for each input dataset (with and without EWs), we quantify the deviation on the SFRs and stellar masses from the "standard" choice. On average, the SFRs are overestimated and the stellar masses are underestimated when EWs are not included as input data. We find a major contribution of the H${\alpha}$ emission line to the broadband photometric measurements of our sources, and a trend of increasing contribution with specific SFR. Using the BPASS models has a significant impact on the derived SFRs and stellar masses. We show that a flexible attenuation recipe provides more accurate estimates of the dust attenuation parameters, especially the differential attenuation which agrees with the original value of Charlot & Fall (2000)., Comment: Accepted in Astronomy & Astrophysics, 19 pages, 15 figures

The clique chromatic number of a graph is the smallest number of colors in a vertex coloring so that no maximal clique is monochromatic. In this paper, we determine the order of magnitude of the clique chromatic number of the random graph G_{n,p} for most edge-probabilities p in the range n^{-2/5} \ll p \ll 1. This resolves open problems and questions of Lichev, Mitsche and Warnke as well as Alon and Krievelevich. One major proof difficulty stems from high-degree vertices, which prevent maximal cliques in their neighborhoods: we deal with these vertices by an intricate union bound argument, that combines the probabilistic method with new degree counting arguments in order to enable Janson's inequality. This way we determine the asymptotics of the clique chromatic number of G_{n,p} in some ranges, and discover a surprising new phenomenon that contradicts earlier predictions for edge-probabilities p close to n^{-2/5}., Comment: 24 pages; minor edits

We report observational evidence of highly turbulent ionized gas kinematics in a sample of 20 Lyman continuum (LyC) emitters (LCEs) at low redshift ($z\sim 0.3$). Detailed Gaussian modeling of optical emission line profiles in high-dispersion spectra consistently shows that both bright recombination and collisionally excited lines can be fitted as one or two narrow components with intrinsic velocity dispersion of $\sigma$ $\sim$ 40-100 km s$^{-1}$, in addition to a broader component with $\sigma \sim$ 100-300 km s$^{-1}$, which contributes up to $\sim$40% of the total flux and is preferentially blueshifted from the systemic velocity. We interpret the narrow emission as highly ionized gas close to the young massive star clusters and the broader emission as a signpost of unresolved ionized outflows, resulting from massive stars and supernova feedback. We find a significant correlation between the width of the broad emission and the LyC escape fraction, with strong LCEs exhibiting more complex and broader line profiles than galaxies with weaker or undetected LyC emission. We provide new observational evidence supporting predictions from models and simulations; our findings suggest that gas turbulence and outflows resulting from strong radiative and mechanical feedback play a key role in clearing channels through which LyC photons escape from galaxies. We propose that the detection of blueshifted broad emission in the nebular lines of compact extreme emission-line galaxies can provide a new indirect diagnostic of Lyman photon escape, which could be useful to identify potential LyC leakers in the epoch of reionization with the JWST., Comment: 11 Pages, 7 Figures. A&A in Press

Double deeply virtual Compton scattering (DDVCS) is a very precise tool for the nucleon tomography. Its measurement requires high luminosity electron beams and precise dedicated detectors, since its amplitude is quite small in the interesting kinematical domain where collinear QCD factorization allows the extraction of quark and gluon generalized parton distributions (GPDs). We analyze the prospects for its study in the JLab energy domain as well as in higher energy electron-ion colliders. Our results are very encouraging for various observables both with an unpolarized and polarized lepton beam. Using various realistic models for GPDs, we demonstrate that DDVCS measurements are indeed very sensitive to their behaviour. Implementing our lowest order cross-section formulae in the EpIC Monte Carlo generator, we estimate the expected number of interesting events., Comment: 6 pages, 5 figures, 1 table, conference proceedings for the 25th International Spin Physics Symposium (SPIN 2023)

In this paper we prove that the $\ell_0$ isoperimetric coefficient for any axis-aligned cubes, $\psi_{\mathcal{C}}$, is $\Theta(n^{-1/2})$ and that the isoperimetric coefficient for any measurable body $K$, $\psi_K$, is of order $O(n^{-1/2})$. As a corollary we deduce that axis-aligned cubes essentially "maximize" the $\ell_0$ isoperimetric coefficient: There exists a positive constant $q > 0$ such that $\psi_K \leq q \cdot \psi_{\mathcal{C}}$, whenever $\mathcal{C}$ is an axis-aligned cube and $K$ is any measurable set. Lastly, we give immediate applications of our results to the mixing time of Coordinate-Hit-and-Run for sampling points uniformly from convex bodies., Comment: 18 pages

Double deeply virtual Compton scattering (DDVCS) is the process where an electron scatters off a nucleon and produces a lepton pair. The main advantage of this process in contrast with deeply virtual and timelike Compton scatterings (DVCS and TCS) is the possibility of directly measuring GPDs for $x\neq\pm\xi$ at leading order in $\alpha_s$ (LO). We present a new calculation of the DDVCS amplitude based on spinor techniques which produce expressions for amplitudes that are perfectly suited for their implementation in numerical simulations. Elements of impact studies, including predictions for experiments at JLab12, JLab20+ and the Electron-Ion Collider (EIC), are studied by means of the PARTONS software and the EpIC Monte Carlo event generator., Comment: 6 pages, 4 figures, proceedings for the DIS2023: XXX International Workshop on Deep-Inelastic Scattering and Related Subjects. arXiv admin note: text overlap with arXiv:2304.03704

Double deeply virtual Compton scattering (DDVCS) is the process where an electron scatters off a nucleon and produces a lepton pair. The main advantage of this process in contrast with deeply virtual and timelike Compton scatterings (DVCS and TCS) is the possibility of directly measuring GPDs for $x\neq\pm\xi$ at leading order in $\alpha_s$ (LO). We present a new calculation of the DDVCS amplitude based on the methods developed by R. Kleiss and W. J. Stirling in the 1980s. These techniques produce expressions for amplitudes that are perfectly suited for implementation in numerical simulations. Via the PARTONS software, the correctness of this new formulation has been tested by comparing the DVCS and TCS limits of DDVCS with independent calculations of DVCS and TCS., Comment: 5 pages, 4 figures, proceedings for the XXIX Cracow Epiphany Conference

We revisit the phenomenology of the deep exclusive electroproduction of a lepton pair, i.e. double deeply virtual Compton scattering (DDVCS), in view of new experiments planned in the near future. The importance of DDVCS in the reconstruction of generalized parton distributions (GPDs) in their full kinematic domain is emphasized. Using Kleiss-Stirling spinor techniques, we provide the leading order complex amplitudes for both DDVCS and Bethe-Heithler sub-processes. Such a formulation turns out to be convenient for practical implementation in the PARTONS framework and EpIC Monte Carlo generator that we use in simulation studies., Comment: 21 pages, 13 figures

Nearby metal-poor starburst dwarf galaxies present a unique opportunity to probe the physics of high-density star formation with a detail and sensitivity unmatched by any observation of the high-z Universe. Here we present the first results from a chemodynamical study of the nearby, gas-rich starburst dwarf CGCG 007-025. We use VLT/MUSE integral field spectroscopy to characterise the properties of the star-forming (SF) gas, from its metal content to its kinematics. The star formation rate (SFR) surface density presents a clumpy distribution, with the brightest knot hosting a 5 Myr young, Wolf-Rayet (WR) population (revealed by the presence of the characteristic 5808\AA~WR bump). The ionised gas kinematics are dominated by disordered motions. A superposition of a narrow ($\sigma \approx$ 50 km s$^{-1}$), intermediate (150 km s$^{-1}$) and broad (1000 km s$^{-1}$) kinematic components are needed to model the emission line profiles in the brightest SF region, suggesting the presence of energetic outflows from massive stars. The gas-phase metallicity of the galaxy spans 0.6 dex and displays a strong anti-correlation with SFR surface density, dropping to 12+log(O/H) = 7.7 in the central SF knot. The spatially-resolved BPTs indicates the gas is being ionised purely by SF processes. Finally, the anti-correlation between the SFR and the gas metallicity points out to accretion of metal-poor gas as the origin of the recent off-centre starburst, in which the infalling material ignites the SF episode., Comment: 15 pages, 11 figures, 1 table; published in MNRAS

In the search for new renewable energy to replace fossil fuels, Hydrogen is one of the most promising candidates for clean energy production. But cheap Hydrogen separation and storage is still a big challenge. Photoelectrochemical devices look promising for the decomposition of the water molecule into $2H_2+O_2$. Every day new materials and combinations are discovered or invented to improve the efficiency of the complex total process. A necessary condition for the photoelectrochemical process to work without a bias voltage is that the minimum of the semiconductor conduction band (CBM) must be more positive than the reduction potential $H^{+}$ to $H_2$, whereas the highest value of the semiconductor valence band (VBM) must be more negative than the oxidation potential of $H_2O$ to $O_2$. Thus, band alignment studies in interfaces of semiconductors with water become of vital importance. In this work, first principles calculations based on density functional theory (DFT) in the all electron and the pseudo potential approaches have been performed for the analysis of the band alignment in $SrTaO_2N/H_2O$ interfaces. Different surface terminations were analyzed, together with the dependence of the gap and band alignment with lattice constants for systems grown on mismatched substrates. Water structures were built from classical molecular dynamics and its electronic structure calculated using DFT. The calculations show that the $SrTaO_2N$ (001) is suitable for photoelectrochemical applications on a wide range of lattice constant a, except for a compression/elongation of -2%, -1% and 3%, while STN (110) results suitable for photoelectrochemical devices over a wider range of lattice constants from -1% to 3%., Comment: 13 pages, 7 figures

Subresiduated lattices were introduced during the decade of 1970 by Epstein and Horn as an algebraic counterpart of some logics with strong implication previously studied by Lewy and Hacking. These logics are examples of subuintuitionistic logics, i.e., logics in the language of intuitionistic logic that are defined semantically by using Kripke models, in the same way as intuitionistic logic is defined, but without requiring of the models some of the properties required in the intuitionistic case. Also in relation with the study of subintuitionistic logics, Celani and Jansana get these algebras as the elements of a subvariety of that of weak Heyting algebras. Here, we study both the implicative and the implicative-infimum subreducts of subresiduated lattices. Besides, we propose a calculus whose algebraic semantics is given by these classes of algebras. Several expansions of this calculi are also studied together to some interesting properties of them.

A theoretical model for two new tellurite-sulfates, namely Na$_2$Cu$_5$(TeO$_3$)(SO$_4$)$_3$(OH)$_4$ and K$_2$Cu$_5$(TeO$_3$)(SO$_4$)$_3$ (OH)$_4$ is determined to be compatible with ab-initio calculations. The results obtained in this work show that some previous speculations in the literature about the couplings are correct, obtaining a model with a mixture of ferromagnetic and antiferromagnetic couplings. We use a combination of numerical techniques to study the magnetic properties of the model. Our numerical calculations based on the density-matrix renormalization group method reveal that the system presents Ising-like magnetization plateaux at rational values of the saturation magnetization., Comment: 7 pages, 8 figures

Most of the hydrogen in the intergalactic medium (IGM) was rapidly ionized at high-redshifts. While observations have established that reionization occurred, observational constraints on the emissivity of ionizing photons at high-redshift remains elusive. Here, we present a new analysis of the Low-redshift Lyman Continuum Survey (LzLCS) and archival observations, a combined sample of 89 star-forming galaxies at z~0.3 with Hubble Space Telescope observations of their ionizing continua (or Lyman Continuum, LyC). We find a strong (6$\sigma$ significant) inverse correlation between the continuum slope at 1550\r{A} (defined as F$_\lambda\propto\lambda^{\beta}$) and both the LyC escape fraction (f$_{esc}$) and f$_{esc}$ times the ionizing photon production efficiency ($\xi_{ ion}$). On average, galaxies with redder continuum slopes have smaller f$_{esc}$ than galaxies with bluer slopes due to higher dust attenuation. More than 5% (20%) of the LyC emission escapes galaxies with $\beta$<-2.1 (-2.6). We find strong correlations between $\beta$ and the gas-phase ionization ([OIII]/[OII] flux ratio; at 7.5$\sigma$ significance), galaxy stellar mass (at 5.9$\sigma$), the gas-phase metallicity (at 4.6$\sigma$), and the observed FUV absolute magnitude (M$_{UV}$ at 3.4$\sigma$). Using previous observations of $\beta$ at high-redshift, we estimate the evolution of f$_{esc}$ with both $z$ and M$_{UV}$. The LzLCS suggest that fainter and lower mass galaxies dominate the ionizing photon budget at higher redshift, possibly due to their rapidly evolving metal and dust content. Finally, we use our correlation between $\beta$ and f$_{ esc}\times\xi_{ion}$ to predict the ionizing emissivity of galaxies during the epoch of reionization. Our estimated emissivities match IGM observations, and suggest that star-forming galaxies emit sufficient LyC photons into the IGM to exceed recombinations near redshifts of 7-8., Comment: 14 pages plus appendix. Submitted to MNRAS. Comments encouraged

The properties that govern the production and escape of hydrogen ionizing photons (Lyman continuum, LyC; with energies >13.6 eV) in star-forming galaxies are still poorly understood, but they are key to identifying and characterizing the sources that reionized the Universe. Here we empirically explore the relationship between the hardness of ionizing radiation and the LyC leakage in a large sample of low-$z$ star-forming galaxies from the recent Hubble Space Telescope Low-$z$ Lyman Continuum Survey. Using Sloan Digital Sky Survey stacks and deep XShooter observations, we investigate the hardness of the ionizing spectra ($Q_{\rm He^+}/Q_{\rm H}$) between 54.4 eV (He$^{+}$) and 13.6 eV (H) from the optical recombination lines HeII 4686A and H$\beta$ 4861A for galaxies with LyC escape fractions spanning a wide range, $f_{\rm esc} \rm (LyC) \simeq 0 - 90\%$. We find that the observed intensity of HeII/H$\beta$ is primarily driven by variations in the metallicity, but is not correlated with LyC leakage. Both very strong ($ \simeq 0.5$) and nonleakers ($ < f_{\rm esc} \rm (LyC) > \simeq 0$) present similar observed intensities of HeII/H$\beta$ at comparable metallicity, between $\simeq 0.01$ and $\simeq 0.02$ for $12 + \log({\rm O/H}) > 8.0$ and $<8.0$, respectively. Our results demonstrate that $Q_{\rm He^+}/Q_{\rm H}$ does not correlate with $f_{\rm esc} \rm (LyC)$, which implies that strong LyC emitters do not show harder ionizing spectra than nonleakers at similar metallicity., Comment: 6 pages, 2 figures, 1 tables. Accepted for publication in A&A Letters. v2: updated to match published version, including new title

In this work, we study the non-hermitian Swanson hamiltonian, particularly the non-PT symmetry phase. We use the formalism of Gel'fand triplet to construct the generalized eigenfunctions and the corresponding spectrum. Depending on the region of the parameter model space, we show that the Swanson hamiltonian represents different physical systems, i.e. parabolic barrier, negative mass oscillators. We also discussed the presence of Exceptional Points of infinite order., Comment: Highlights: 1) PT-symmetry Swanson Hamiltonian 2) Exceptional Points 3) Gel'fand triplet

The Minimal Linear $\sigma$ Model is a useful theoretical laboratory. One can investigate in a perturbative renormalisable model the properties of the Higgs boson as a pseudo-Goldstone boson, the phenomenological effects of the radial mode of the field $\mathtt{s}$ which spontaneously breaks the global $SO(5)$ symmetry and the validity of conclusions based on the Effective Field Theory approach with the field $\mathtt{s}$ in the spectrum, after the decoupling of heavy degrees of freedom. In this paper all those issues are discussed in the framework of the Minimal Linear $\sigma$ Model with CP violating phases leading to pseudoscalar components in the effective Standard Model Yukawa couplings. Also the character of the electroweak phase transition in the presence of the field $\mathtt{s}$ is investigated., Comment: 32 pages, 6 figures, V2: improved discussion on the EFT treatment and on first order phase transition; references added; main results unchanged; version accepted for publication on EPJC

This paper presents the application of two classical models to high-resolution electric field measurements carried out in a hollow cathode discharge operated in pure hydrogen plasma. The electric field determination has been done via the Stark shifting and splitting of the 2S level of hydrogen, followed by optogalvanic detection. Two classical models, Rickards' and Wro{\'n}ski's, are applied to these measurements with the objective of obtaining a first estimation on the discharge dynamics. The chosen models provide an idea of the ions movement, their energy and their mean free path at the cathode fall region, as well as the electric field strength behaviour depending on the discharge characteristics.

In this work, a non-intrusive, spatially resolved, spectro-tomographic optical diagnostic of the electronic density and temperature on the linear plasma column Mistral is presented. Coupling of spectroscopy and tomography technique gives access to the local plasma light emission at different wavelengths (visible and near IR) in an argon plasma. Taking advantage of the symmetry of the Mistral experiment, the diagnostic results are validated and the plasma is found to correspond to a corona equilibrium state. With the use of another spectrometer and a Langmuir probe, we propose a non-intrusive method to determine the electronic density and temperature of each pixel of the tomographic images of the plasma. The obtained results are in good agreement with the Langmuir probe ones.

In this paper, it is presented a novel strategy to optimize the determination of magnetic couplings by using ab-initio calculations of the energy. This approach allows determining efficiently, in terms of a proposed effective magnetic spin model, an optimal set of magnetic configurations to be simulated by DFT methods. Moreover, a procedure to estimate the values of the coupling constants and their error bounds from the estimated energies is proposed. This method, based on Monte Carlo sampling, takes into account the accuracy of the ab - initio simulations. A strategy to refine models reusing previously computed configuration energies is also presented. We apply the method to determine a magnetic model for the recently synthesized material Bi$_3$Mn$_4$O$_{12}$(NO$_3$). Finally, an open source software that implements and automatizes the whole process is presented., Comment: 8 pages, 4 figures