ALBERT

Description: A correction to this paper has been published: 10.1140/epjc/s10052-021-09344-w

Description: As any $$e^+e^-$$ e + e - scattering process can be accompanied by a hard photon emission from the initial state radiation, the analysis of the energy spectrum and angular distributions of those photons can be used to search for hard processes with an invisible final state. Thus high energy $$e^+e^-$$ e + e - colliders offer a unique possibility for the most general search of dark matter (DM) based on the mono-photon signature. We consider production of DM particles at the International Linear Collider (ILC) and Compact Linear Collider (CLIC) experiments via a light mediator exchange. Detector effects are taken into account within the Delphes fast simulation framework. Limits on the light DM production in a simplified model are set as a function of the mediator mass and width based on the expected two-dimensional distributions of the reconstructed mono-photon events. The experimental sensitivity is extracted in terms of the DM production cross section. Limits on the mediator couplings are then presented for a wide range of mediator masses and widths. For light mediators, for masses up to the centre-of-mass energy of the collider, coupling limits derived from the mono-photon analysis are more stringent than those expected from direct resonance searches in decay channels to SM particles.

Description: Remotely sensed data such as satellite photos and radar images can be used to produce geological maps on arid regions, where the vegetation coverage does not have a significant effect. In central Tunisia, the Jebel Meloussi area has unique geological features and characteristic morphology (i.e. flat areas with dune fields in contrast with hills of folded and eroded stratigraphic sequences), which makes it an ideal area for testing new methods of automatic terrain classification. For this, data from the Sentinel 2 satellite sensor and the SRTM-based MERIT DEM (digital elevation model) were used in the present study. Using R scripts and the random forest classification method, modelling was performed on four lithological variables—derived from the different bands of the Sentinel 2 images—and two morphometric parameters for the area of the 1:50,000 geological map sheet no. 103. The four lithological variables were chosen to highlight the iron-bearing minerals since the spectral parameters of the Sentinel 2 sensors are especially useful for this purpose. The training areas of the classification were selected on the geological map. The results of the modelling identified Eocene and Cretaceous evaporite-bearing sedimentary series (such as the Jebs and the Bouhedma Formations) with the highest producer accuracy (〉 60% of the predicted pixels match with the map). The pyritic argillites of the Sidi Khalif Formation were also recognized with the same accuracy, and the Quaternary sebhkas and dunes were also well predicted. The study concludes that the classification-based geological map is useful for field geologist prior to field surveys.

Description: We consider the inverse Seesaw scenario for neutrino masses with the approximate Lepton number symmetry broken dynamically by a scalar with Lepton number two. We show that the Majoron associated to the spontaneous symmetry breaking can alleviate the Hubble tension through its contribution to $$Delta N_ext {eff}$$ Δ N eff and late decays to neutrinos. Among the additional fermionic states required for realizing the inverse Seesaw mechanism, sterile neutrinos at the keV-MeV scale can account for all the dark matter component of the Universe if produced via freeze-in from the decays of heavier degrees of freedom.

Description: We present the software framework underlying the NNPDF4.0 global determination of parton distribution functions (PDFs). The code is released under an open source licence and is accompanied by extensive documentation and examples. The code base is composed by a PDF fitting package, tools to handle experimental data and to efficiently compare it to theoretical predictions, and a versatile analysis framework. In addition to ensuring the reproducibility of the NNPDF4.0 (and subsequent) determination, the public release of the NNPDF fitting framework enables a number of phenomenological applications and the production of PDF fits under user-defined data and theory assumptions.

Description: We report the results of a search for a new vector boson ($$ A'$$ A ′ ) decaying into two dark matter particles $$chi _1 chi _2$$ χ 1 χ 2 of different mass. The heavier $$chi _2$$ χ 2 particle subsequently decays to $$chi _1$$ χ 1 and an off-shell Dark Photon $$ A'^* ightarrow e^+e^-$$ A ′ ∗ → e + e - . For a sufficiently large mass splitting, this model can explain in terms of new physics the recently confirmed discrepancy observed in the muon anomalous magnetic moment at Fermilab. Remarkably, it also predicts the observed yield of thermal dark matter relic abundance. A detailed Monte-Carlo simulation was used to determine the signal yield and detection efficiency for this channel in the NA64 setup. The results were obtained re-analyzing the previous NA64 searches for an invisible decay $$A' ightarrow chi overline{chi }$$ A ′ → χ χ ¯ and axion-like or pseudo-scalar particles $$a ightarrow gamma gamma $$ a → γ γ . With this method, we exclude a significant portion of the parameter space justifying the muon g-2 anomaly and being compatible with the observed dark matter relic density for $$A'$$ A ′ masses from 2$$m_e$$ m e up to 390 MeV and mixing parameter $$varepsilon $$ ε between $$3imes 10^{-5}$$ 3 × 10 - 5 and $$2imes 10^{-2}$$ 2 × 10 - 2 .

Description:  In the present study, a small piled raft foundation has been simulated numerically through PLAXIS 3-D software. The objective of this study was to investigate the effect of governing parameters such as pile length, pile spacing, pile diameter, and number of piles on the settlement and load-bearing behavior of piled raft, so as to achieve the optimum design for small piled raft configurations. An optimized design of a piled raft is defined as a design with allowable center and differential settlements and satisfactory bearing behavior for a given raft geometry and loading. The results indicated that, with increase in pile length, pile spacing, pile diameter, and number of piles, both the center settlement ratio and differential settlement ratio decreased. The load-bearing capacity of piled raft increased with increase in pile length, pile spacing, pile diameter, and number of piles. Furthermore, the percentage load carried by the piles increased as the pile length, pile spacing, pile diameter, and number of piles increased. The bending moment and shear force in corner pile are noted to be more, and they decreased towards the center pile. With increase in pile length, the maximum raft bending moment decreased, whereas the maximum shear force in the raft increased. Further, with increase in pile spacing, pile diameter, and number of piles, the maximum bending moment and maximum shear force in the raft increased. The optimum parameters for the piled raft foundation can be selected efficiently with the consideration of maximum bending moment and maximum shear force while designing the piled raft foundation. Thus, the results of this study can be used as guidelines for achieving optimum design for small piled raft foundation.

Description: In this paper, we study Friedmann cosmology with time-varying vacuum energy density in the context of Brans–Dicke theory. We consider an isotropic and homogeneous flat space, filled with a matter-dominated perfect fluid and a dynamical cosmological term $$varLambda (t) $$ Λ ( t ) , obeying the equation of state of the vacuum. As the exact nature of a possible time-varying vacuum is yet to be found, we explore $$varLambda (t)$$ Λ ( t ) given by the phenomenological law $$varLambda (t)=lambda +sigma H$$ Λ ( t ) = λ + σ H , where $$lambda $$ λ and $$sigma $$ σ are positive constants. We solve the model and then focus on two different cases $$varLambda _{H1}$$ Λ H 1 and $$varLambda _{H2}$$ Λ H 2 by assuming $$varLambda =lambda $$ Λ = λ and $$varLambda =sigma H$$ Λ = σ H , respectively. Notice that $$varLambda _{H1}$$ Λ H 1 is the analog of the standard $$varLambda $$ Λ CDM, but within the Brans–Dicke cosmology. We find the analytical solution of the main cosmological functions such as the Hubble parameter, the scale factor, deceleration and equation of state parameters for these models. In order to test the viability of the cosmological scenarios, we perform two sets of joint observational analyses of the recent Type Ia supernova data (Pantheon), observational measurements of Hubble parameter data, Baryon acoustic oscillation/Cosmic microwave background data and Local Hubble constant for each model. For the sake of comparison, the same data analysis is performed for the $$varLambda $$ Λ CDM model. Each model shows a transition from decelerated phase to accelerated phase and can be viewed as an effective quintessence behavior. Using the model selection criteria AIC and BIC to distinguish from existing dark energy models, we find that the Brans–Dicke analog of the $$varLambda $$ Λ -cosmology (i.e. our model $$varLambda _{H1}$$ Λ H 1 ) performs at a level comparable to the standard $$varLambda $$ Λ CDM, whereas $$varLambda _{H2}$$ Λ H 2 is less favoured.

Description: We develop a method for computing the Bogoliubov transformation experienced by a confined quantum scalar field in a globally hyperbolic spacetime, due to the changes in the geometry and/or the confining boundaries. The method constructs a basis of solutions to the Klein–Gordon equation associated to each compact Cauchy hypersurface of constant time. It then provides a differential equation for the linear transformation between bases at different times. The transformation can be interpreted physically as a Bogoliubov transformation when it connects two regions in which a time symmetry allows for a Fock quantisation. This second article on the method is dedicated to spacetimes with timelike boundaries that do not remain static in any synchronous gauge. The method proves especially useful in the regime of small perturbations, where it allows one to easily make quantitative predictions on the amplitude of the resonances of the field. Therefore, it provides a crucial tool in the growing research area of confined quantum fields in table-top experiments. We prove this utility by addressing two problems in the perturbative regime: Dynamical Casimir Effect and gravitational wave resonance. We reproduce many previous results on these phenomena and find novel results in an unified way. Possible extensions of the method are indicated. We expect that our method will become standard in quantum field theory for confined fields.

Description: The Sermo Reservoir is located in Kulon Progo District, Special Region of Yogyakarta, Indonesia. It plays a vital role in providing water to its surrounding communities. According to the geological structure of this area, a fault exists near the Ngrancah River and passes through the reservoir’s inundation. At present, a network consists of 15 Global Navigation Satellite System (GNSS) monitoring stations spread around the Sermo Fault to monitor its deformation. However, this network was designed without consideration of geological parameters. This study aimed to design an optimal deformation monitoring network of the Sermo Fault by taking into account geological information and evaluate the existing network, specifically, the optimal distance for the station to the fault plane. Geological surveys were carried out to obtain information regarding the type and characteristics of the fault. This information was used as one of the parameters in the optimization design, using sensitivity criteria, of a network to monitor for the optimal distance between the observation station and fault. Using the strike-slip fault model, the optimal distance obtained was from 4.5 to 8.5 km from the fault plane. The existing stations of the Sermo Fault deformation monitoring network are about 0.07–3.3 km away from the fault. Therefore, the network is insufficiently sensitive and needs to be developed by adding stations that are more than 4.5 km away from the fault. This study designed an alternative network by rearranging the stations’ location to obtain a better configuration and sensitivity.