Soft Pomerons and the Forward LHC Data

Recent data from LHC13 by the TOTEM Collaboration on $\sigma_{tot}$ and $\rho$ have indicated disagreement with all the Pomeron model predictions by the COMPETE Collaboration (2002). On the other hand, as recently demonstrated by Martynov and Nicolescu (MN), the new $\sigma_{tot}$ datum and the unexpected decrease in the $\rho$ value are well described by the maximal Odderon dominance at the highest energies. Here, we discuss the applicability of Pomeron dominance through fits to the \textit{most complete set} of forward data from $pp$ and $\bar{p}p$ scattering. We consider an analytic parametrization for $\sigma_{tot}(s)$ consisting of non-degenerated Regge trajectories for even and odd amplitudes (as in the MN analysis) and two Pomeron components associated with double and triple poles in the complex angular momentum plane. The $\rho$ parameter is analytically determined by means of dispersion relations. We carry out fits to $pp$ and $\bar{p}p$ data on $\sigma_{tot}$ and $\rho$ in the interval 5 GeV - 13 TeV (as in the MN analysis). Two novel aspects of our analysis are: (1) the dataset comprises all the accelerator data below 7 TeV and we consider \textit{three independent ensembles} by adding: either only the TOTEM data (as in the MN analysis), or only the ATLAS data, or both sets; (2) in the data reductions to each ensemble, uncertainty regions are evaluated through error propagation from the fit parameters, with 90 \% CL. We argument that, within the uncertainties, this analytic model corresponding to soft Pomeron dominance, does not seem to be excluded by the \textit{complete} set of experimental data presently available.Comment: 10 pages, 4 figures, 1 table. Two paragraphs and four references added. Accepted for publication in Phys. Lett.

Proton-proton forward scattering at the LHC

Recently the TOTEM experiment at the LHC has released measurements at $\sqrt{s} = 13$ TeV of the proton-proton total cross section, $\sigma_{tot}$, and the ratio of the real to imaginary parts of the forward elastic amplitude, $\rho$. Since then an intense debate on the $C$-parity asymptotic nature of the scattering amplitude was initiated. We examine the proton-proton and the antiproton-proton forward data above 10 GeV in the context of an eikonal QCD-based model, where nonperturbative effects are readily included via a QCD effective charge. We show that, despite an overall satisfactory description of the forward data is obtained by a model in which the scattering amplitude is dominated by only crossing-even elastic terms, there is evidence that the introduction of a crossing-odd term may improve the agreement with the measurements of $\rho$ at $\sqrt{s} = 13$ TeV. In the Regge language the dominant even(odd)-under-crossing object is the so called Pomeron (Odderon).Comment: 5 pages, 2 figures, 1 table. Phenomenological approach revised, results and conclusions changed, suggesting now the presence of Odderon effects in forward scattering (once confirmed the TOTEM data at 13 TeV

Soft Pomeron in light of the LHC correlated data

The LHC has released precise measurements of elastic proton-proton scattering that provide a unique constraint on the asymptotic behavior of the scattering amplitude at high energies. Recent reanalyses of part of these data indicate that the central values of some forward quantities would be different than initially observed. We introduce correlation information between the original and the reanalyzed data sets in a way suitable for a global fitting analysis of all data. The careful treatment of correlated errors leads to much less stringent limits on the $\rho$ uncertainty and sets up the stage for describing the forward data using a scattering amplitude dominated by only crossing-even terms. In the light of these correlated data we determine the parameters of the soft Pomeron from the Regge theory. We use Born-level and eikonalized amplitudes. In the Born-level case we estimate the contribution of the double Pomeron exchange, while in the latter case we investigate the role of the eikonalization in both the one- and two-channel models. The role of the proton-Pomeron vertex form and of the nearest $t$-channel singularity in the Pomeron trajectory receives particular attention. We discuss the implications of our results and present predictions for the total cross section and the $\rho$ parameter in proton-proton collisions at LHC and cosmic ray energies.Comment: 17 pages, 6 figures, 5 tables, minor typos fixed. Version to be published in Phys. Rev. D. arXiv admin note: text overlap with arXiv:1908.0104

Medición de impactos en una terraza verde para la definición de estandares de eficiencia en sistemas de techos verdes intensivos y extensivos en condiciones urbanas. Caso de estudio: Ciudad de Córdoba

Una alternativa para moderar el equilibrio en los ecosistemas urbanos e integrar la vegetación a las ciudades, lo constituyen los techos verdes. Dichos sistemas aportan servicios ecosistemicos, como la mitigación de las variaciones de temperatura entre el exterior y el interior de las unidades habitacionales, contribuyendo a la eficiencia energética de las construcciones edilicias. En el presente proyecto de investigación se evalúa la adecuación de esta tecnología a condiciones constructivas reales; como así también el impacto de los dos tipos de sistemas: el extensivo y el intensivo, comparándolos con un techo blanco como testigo. En dos aulas taller contiguas de la facultad de arquitectura se instaló un sistema extensivo de techos verdes (80 m2) y la otra se pintó la loza de blanco (testigo). En el techo del aula testigo se instalaron 3 cubos de simulación de 1 m3 para simular ambos sistemas (extensivo e intensivo) y comparar con el testigo. Se colocaron sensores exteriores, de loza e interiores tanto en ambas aulas como en los cubos, para evaluar la eficiencia energética y en los cubos además, la escorrentía. Se están procesando y analizando los datos recibidos para estimar las propiedades térmicas, las diferencias de temperaturas en los diferentes espacios, así como el impacto energéticode ambos sistemas. Al mismo tiempo se está analizando la detección y detención de la escorrentía de las lluvias recibidas en ese período. Este proyecto permite medir el impacto positivo del techo verde, establecer comparaciones entre sistemas constructivos, y dimensionar la magnitud de algunos de los servicos ecosistémicos que este mismo presta (e.g. regulación térmica, colecta del agua de lluvia, retención y detención de escorrentía, entre otros). La estimación certera de estos beneficios potenciales permitirá la definición de estándares de eficiencia