Cornering the Planck AlensA_{lens} tension with future CMB data

The precise measurements of Cosmic Microwave Background Anisotropy angular power spectra made by the Planck satellite show an anomalous value for the lensing amplitude, defined by the parameter $A_{lens}$, at more than $2$ standard deviations. In this paper, after discussing the current status of the anomaly, we quantify the potential of future CMB measurements in confirming/falsifying the $A_{lens}$ tension. We find that a space-based experiment as LiteBIRD could falsify the current $A_{lens}$ tension at the level of $5$ standard deviations. Similar constraints can be achieved by a Stage-III experiment assuming an external prior on the reionization optical depth of $\tau=0.055\pm0.010$ as already provided by the Planck satellite. A Stage-IV experiment could further test the $A_{lens}$ tension at the level of $10$ standard deviations. A comparison between temperature and polarization measurements made at different frequencies could further identify possible systematics responsible for $A_{lens}>1$. We show that, in the case of the CMB-S4 experiment, polarization data alone will have the potential of falsifying the current $A_{lens}$ anomaly at more than five standard deviation and to strongly bound its frequency dependence. We also evaluate the future constraints on a possible scale dependence for $A_{lens}$.Comment: 5 pages, 4 figure

A look at the Hubble speed from first principles

We introduce a novel way of measuring $H_0$ from a combination of independent geometrical datasets, namely Supernovae, Baryon Acoustic Oscillations and Cosmic Chronometers, without the need of calibration nor of the choice of a cosmological model. Our method builds on the \emph{distance duality relation} which sets the ratio of luminosity and angular diameter distances to a fixed scaling with redshift, for any metric theory of gravity with standard photon propagation. In our analysis of the data we employ Gaussian Process algorithms to obtain constraints that are independent from the underlying cosmological model. We find $H_0=69.5\pm1.7$ Km/s/Mpc, showing that it is possible to constrain $H_0$ with an accuracy of $2\%$ with minimal assumptions. While competitive with current astrophysical and cosmological constraints, our result is not precise enough to solve the Hubble tension in a definitive way. However, we uncover some interesting features that hint at a twofold solution of the tension.Comment: 7 pages, 5 figures. Any comments are mostly welcom

Current and Future constraints on single-field α\alpha-Attractor model

We study here the observational constraints on single-field inflationary models achievable with the next generation of CMB experiments. We particularly focus on a Stage-IV like experiment and forecasts its constraints on inflationary parameters in the context of $\alpha$-attractor inflation comprising a large class of single-field models. To tailor our forecasts we use as a fiducial model the results obtained with current CMB and LSS data, assuming the $\alpha$-model a priori. We found that current CMB data are able to place a tight bound on the ratio of the tensor-to-scalar ratio with the alpha parameter $r/\alpha = 3.87^{+0.78}_{-0.94}\cdot 10^{-3}$ and on the running of the scalar index $\alpha_S = -6.4^{+1.6}_{-1.3}\cdot 10^{-4}$ with a value of the scalar index consistent with current constraints. In the optimistic scenario of detection of primordial gravitational waves in the CMB B-mode polarization power spectra, we found that CMB-S4 will be able to achieve a $15\%$ bound on the value of the parameter $\alpha = 1.01^{+0.14}_{-0.18}$. This bound clearly show the ability of CMB-S4 to constrain not only the energy scale of inflation but also the shape of its potential. Enlarging the baseline model to also include the neutrino sector merely reduce the accuracy of $5\%$ leading to $\alpha = 1.07^{+0.18}_{-0.23}$ so that our main conclusions are still valid.Comment: 8 pages, 5 figures. Comments are welcom

What is the amplitude of the Gravitational Waves background expected in the Starobinsky model ?

The inflationary model proposed by Starobinski in 1979 predicts an amplitude of the spectrum of primordial gravitational waves, parametrized by the tensor to scalar ratio, of $r=0.0037$ in case of a scalar spectral index of $n_S=0.965$. This amplitude is currently used as a target value in the design of future CMB experiments with the ultimate goal of measuring it at more than five standard deviations. Here we evaluate how stable are the predictions of the Starobinski model on $r$ considering the experimental uncertainties on $n_S$ and the assumption of $\Lambda$CDM. We also consider inflationary models where the $R^2$ term in Starobinsky action is generalized to a $R^{2p}$ term with index $p$ close to unity. We found that current data place a lower limit of $r>0.0013$ at $95 \%$ C.L. for the classic Starobinski model, and predict also a running of the scalar index different from zero at more than three standard deviation in the range $dn/dlnk=-0.0006_{-0.0001}^{+0.0002}$. A level of gravitational waves of $r\sim0.001$ is therefore possible in the Starobinski scenario and it will not be clearly detectable by future CMB missions as LiteBIRD and CMB-S4. When assuming a more general $R^{2p}$ inflation we found no expected lower limit on $r$, and a running consistent with zero. We found that current data are able to place a tight constraints on the index of $R^{2p}$ models at $95\%$ C.L. i.e. $p= 0.99^{+0.02}_{-0.03}$.Comment: Corrected a typo in the potential normalizatio

Suárez y la primera certeza del sentido común

The first certainty of common sense originally proves a multiplicity of things irreducible to each other. The unity of the ens is not an original empirical datum, but a derived concept, precisely because it is common to many things. From this point of view, it is necessary to distinguish between the Suarezian philosophy and the Parmenidean philosophy. In particular, the way that the question concerning the dialectical opposition between being and nothing is approached in the Metaphysical Disputations cannot be interpreted as the manifestation of a Parmenidean position. The starting point of the Suarezian reflection is the plurality of the entities.La primera certeza del sentido común comprueba originariamente una multiplicidad de cosas irreductibles entre sí. La unidad del ens no es un dato empírico originario, sino un concepto derivado, precisamente porque es común a muchas cosas. Desde este punto de vista, hay que distinguir entre la filosofía suarista y la filosofía parmenídea. En particular, la manera en que se aborda la cuestión concerniente a la oposición dialéctica entre el ser y la nada en las Disputaciones metafísicas no puede ser interpretada como la manifestación de una postura parmenídea. El punto de arranque de la reflexión suarista es la pluralidad de los entes

Observaciones acerca de la compatibilidad entre la filosofía suarista y la lógica alética

Livi's alethic logic is compatible with Suárez's philosophy. First, the Suarezian thesis that the verb “sum” of a proposition includes in itself its own participle does not represent a denial of the Livian thesis that existential judgments logically precede attributive judgments. Second, Livi and Suárez have the same conception about the scientific status of metaphysics. Finally, both the Italian philosopher and the Spanish metaphysician maintain that the first principles can acquire a cognitive significance only if they are related to what is manifested in experience.  La lógica alética de Livi es compatible con la filosofía de Suárez. En primer lugar, la tesis suarista de que el verbo “sum” de una proposición incluye en sí mismo su propio participio no representa una negación de la tesis liviana de que los juicios existenciales preceden lógicamente a los juicios atributivos. En segundo lugar, Livi y Suárez tienen la misma concepción sobre el estatuto científico de la metafísica. Por último, tanto el filósofo italiano como el metafísico español sostienen que los primeros principios pueden adquirir una significación cognitiva solo si están relacionados con lo que se manifiesta en la experiencia

Higher-Curvature Corrections and Tensor Modes

Higher-curvature corrections to the effective gravitational action may leave signatures in the spectrum of primordial tensor perturbations if the inflationary energy scale is sufficiently high. In this paper we further investigate the effects of a coupling of the Inflaton field to higher-curvature tensors in models with a minimal breaking of conformal symmetry. We show that an observable violation of the tensor consistency relation from higher-curvature tensors implies also a relatively large running of the tensor tilt, enhanced even by some order of magnitude with respect to the standard slow roll case. This may leave signatures in the tensor two-point function that we could test to recognize higher-curvature effects, above all if they are translated into a blue tilted spectrum visible by future Gravitational Wave experiments. Exploiting current cosmic microwave background and gravitational wave data we also derive constraints on the inflationary parameters, inferring that large higher-curvature corrections seem to be disfavored.Comment: 11 pages, 3 figure

use of diesel biodiesel bioethanol blends in farm tractors first results obtained with a mixed experimental numerical approach

Abstract The fuelling of internal combustion engines with biofuels has certainly many environmental and energetic advantages. These advantages are particularly effective in the agricultural sector, where an integrated biofuel supply-chain would further benefit the overall carbon balance. Unfortunately, there are also some drawbacks, mainly concerning the engine performances (lowering of the torque curve), but also environmental (possible raising of the NOx emissions). However, by appropriately mixing two biofuels with known opposite effects on the combustion process, it is theoretically possible to compensate the aforementioned disadvantages. In this work, some experiments were carried out in this direction by fuelling a farm tractor with four different fuel mixes; the collected data were processed through the Response Surface Methodology to obtain multi-parameter regression equations useful to identify the optimal fuel mixtures composition. Thanks to this approach, it was found that biodiesel has a positive effect on the torque, while the addition of bioethanol has a much bigger detrimental effect; on the contrary, bioethanol should be added to a mixture with a minimum of 8-12 % of biodiesel to get advantages in terms of NOx concentration reduction

Strongly lensed supernovae as a self-sufficient probe of the distance duality relation

Theoretical Physic