bluuebunny/crossref_metadata_2025_split huggingface dataset:
A dark vector resonance at CLIC *
Authors: Callender Constanza , Zerwekh Alfonso R. 
Published: May 2019

Abstract
One of the main problems in particle physics is to understand the origin and nature of dark matter. An exciting possibility is to consider that dark matter belongs to a new complex but hidden sector. In this paper, we assume the existence of a strongly interacting dark sector consisting of a new scalar doublet and new vector resonances, in accordance with the model recently proposed by our group. Since it was found in the previous work that it is very challenging to find the new vector resonances at the LHC, here we study the possibility of finding them at the future Compact Linear Collider (CLIC) running at

TeV. We consider two distinct scenarios. In the first, when the non-standard scalars are heavy, the dark resonance is intense enough to make its discovery possible at CLIC when the resonance mass is in the range [2000, 3000] GeV. In the second scenario, when the non-standard scalars are light, the new vector boson is too broad to be recognized as a resonance, and is not detectable except when the mass of the scalars is close to (but smaller than) half of the resonance mass and the scale of the dark sector is high. In all positive cases, less than a tenth of the maximum integrated luminosity is needed to reach the discovery level. Finally, we also comment on the mono-

production.
Structure, formation, and decay of

system by Faddeev-AGS calculations
Authors: Marri S. , Kalantari S. Z. , Esmaili J. 
Published: May 2019

Abstract
The Faddeev AGS equations for the coupled-channels

system with quantum numbers I= 1/2 and S= 0 are solved. Using separable potentials for the

interaction, we calculate the transition probability for the

reaction. The possibility to observe the trace of the

quasi-bound state in

mass spectra was studied. Various types of chiral-based and phenomenological potentials are used to describe the

interaction. Finally, we show that we can observe the signature of the

quasi-bound state in the mass spectra, as well as the trace of branch points in the observables.
Constraining symmetry energy at subnormal density by isovector giant dipole resonances of spherical nuclei *
Authors: Su Jun 
Published: May 2019

Abstract
In our previous study, the deduced Langevin equation has been applied to investigate the isoscalar giant monopole resonance. In the current study, the framework is extended to study the isovector giant dipole resonance (IVGDR). The potential well in the IVGDR is calculated by separating the neutron and proton densities based on the Hartree-Fock ground state. Subsequently, the Langevin equation is solved self-consistently, resulting in the centroid energy of the IVGDR without width. The symmetry energy around the density of 0.02 fm−3 contributes the most to the potential well in the IVGDR. By comparison with the updated experimental data of IVGDR energies in spherical nuclei, the calculations within 37 sets of Skyrme functionals suggest the symmetry energy to be in the range of 8.13-9.54 MeV at a density of 0.02 fm−3.
New insights on low energy πN scattering amplitudes: comprehensive analyses at

level *
Authors: Wang Yu-Fei , Yao De-Liang , Zheng Han-Qing 
Published: May 2019

Abstract
A production representation of partial-wave S matrix is utilized to construct low-energy elastic pion-nucleon scattering amplitudes from cuts and poles on complex Riemann sheets. Among them, the contribution of left-hand cuts is estimated using the

results obtained in covariant baryon chiral perturbation theory within the extended-on-nass-shell scheme. By fitting to data on partial-wave phase shifts, it is indicated that the existences of hidden poles in S
11 and P
11 channels, as conjectured in our previous paper [Eur. Phys. J. C, 78(7): 543 (2018)], are firmly established. Specifically, the pole mass of the S
11 hidden resonance is determined to be (895±81)−(164±23)i MeV, whereas, the virtual pole in the P
11 channel locates at (966±18) MeV. It is found that analyses at the

level improves significantly the fit quality, comparing with the previous

one. Quantitative studies with cautious physical discussions are also conducted for the other S- and P-wave channels.
Pseudoscalar meson and baryon octet interaction with strangeness zero in the unitary coupled-channel approximation
Authors: Sun Bao-Xi , Zhao Si-Yu , Wang Xiang-Yu 
Published: May 2019

Abstract
The interaction of the pseudoscalar meson and the baryon octet is investigated by solving the Bethe-Salpeter equation in the unitary coupled-channel approximation. In addition to the Weinberg-Tomozawa term, the contribution of the

and

channel potentials in the S-wave approximation are taken into account. In the sector of isospin

and strangeness

, a pole is detected in a reasonable region of the complex energy plane of

in the center-of-mass frame by analyzing the behavior of the scattering amplitude, which is higher than the

threshold and lies on the third Riemann sheet. Thus, it can be regarded as a resonance state and might correspond to the

particle of the Particle Data Group (PDG) review. The coupling constants of this resonance state to the

,

,

and

channels are calculated, and it is found that this resonance state couples strongly to the hidden strange channels. Apparently, the hidden strange channels play an important role in the generation of resonance states with strangeness zero. The interaction of the pseudoscalar meson and the baryon octet is repulsive in the sector of isospin

and strangeness

, so that no resonance state can be generated dynamically.
Time-crystal ground state and production of gravitational waves from QCD phase transition *
Authors: Addazi Andrea , Marcianò Antonino , Pasechnik Roman 
Published: May 2019

Abstract
We propose a novel mechanism for the production of gravitational waves in the early Universe that originates from the relaxation processes induced by the QCD phase transition. While the energy density of the quark-gluon mean-field is monotonously decaying in real time, its pressure undergoes a series of violent oscillations at the characteristic QCD time scales that generate a primordial multi-peaked gravitational waves signal in the radio frequencies’ domain. The signal is an echo of the QCD phase transition that is accessible by planned measurements at the FAST and SKA telescopes.
Numerical analysis of advection-diffusion problems on 2D general-shaped domains by means of a RBF Collocation Meshless Method
Authors: Zamolo Riccardo , Nobile Enrico 
Published: May 2019

Abstract
A Collocation Meshless Method based on local Radial Basis Function (RBF) interpolation is employed to solve two-dimensional advection-diffusion problems with particular reference to the incompressible Navier-Stokes equations in their transient form, i.e., unsteady flows, using primitive variables (u, p). A projection scheme is employed to decouple the continuity and momentum equations; particular attention is given to the choice of the required solvers. This approach is applied to the simulation of unsteady flows for two typical test cases, i.e., the lid-driven cavity problem and the flow past a circular cylinder between parallel walls. Numerical results compare very favorably with literature ones, confirming that this approach can be effectively employed in the numerical simulation of unsteady flows on practical geometries where complex node distributions and large number of nodes are required.
Low-order dynamic model of a domestic electric oven Part II: parameter identification and model validation for the static heating mode
Authors: Lucchi Michael , Lorenzini Marco , Roberti Giovanni 
Published: May 2019

Abstract
Appliances are responsible for almost the 25% of the overall environmental impact of buildings, and, among these, electric domestic ovens represent a low-efficiency category when considering flats, with an energy efficiency between 10% and 12%, thus stimulating the development of more efficient technologies. The energy performance of such an appliance is determined through a test according to the EN 60350-1 European standard, which, among others, requires suitable control of the oven centre temperature. Since the development of reliable dynamic models represents a high-potential tool to design better control strategies, the aim of this work is to create a model simulating the transient thermal behaviour during the static, i.e. non-ventilated, heating mode of an electric domestic oven within the cabinet adopted for energy consumption tests; the model must be able to predict the main temperatures within the cavity, with particular attention to the oven centre. A lumped parameter approach based on the thermoelectric analogy was chosen, in order to obtain a low-order dynamic model suitable for control design purposes. Since the model strives to reproduce the transient behaviour of the oven centre temperature, a single lumped parameter simulating the thermal behaviour of the whole oven cavity was unsuitable and a certain level of macroscopic discretization had therefore to be introduced. Thus, the oven cavity was modelled with eight parameters, representing its main parts like the walls, the glass door and the air in the cavity; also, the temperature probe, a Pt500 as is customary for such devices, was included in the model, since this is the only temperature feedback during operation and its presence in the model could lead to an easier implementation of efficient control logics. Three lumped parameters simulating the thermal behaviour of the heaters were also considered, leading to an 11
th
order model.
A Mesoscale-Microscale approach for the energy analysis of buildings
Authors: Montelpare S , D’Alessandro V , Lops C , Costanzo E , Ricci R 
Published: May 2019

Abstract
This work is aimed to suggest a numerical approach able to select the most useful building orientation with respect to the local wind in complex urban areas. It is showed a mesoscale-microscale numerical approach able to predict local flow patterns for building designers. The city of Ancona was selected to analyse wind patterns over complex orography in presence of buildings. The analysed area is characterized by a densely built hilly promontory flanked by a poorly urbanized valley. Two buildings were chosen to carry out energy analyses. At first, the MM5 weather prediction model is used to assess the wind patterns and the wind occurrence distribution. The 2010 year was simulated and compared with real data from a met-mast. After, computational fluid dynamic (CFD) analyses are conducted with and without the surrounding buildings to appreciate speed and inflow e˙ects. CFD results showed great changes in the examined building area. The final step was the energy simulation, by means of EnergyPlus, of two multistoried buildings equipped with a double skin façade; results show a great impact on the energy consumption by comparing a wrong orientation with respect to the best solution derived from the mesoscale-microscale approach.
Sustainability assessment and performance evaluation of a Ground Coupled Heat Pump system: coupling a model based on COMSOL Multiphysics and a MATLAB heat pump model
Authors: Alimonti C , Soldo E , Minniti S , Speetjens MFM 
Published: May 2019

Abstract
The present study investigates the sustainable use of a ground coupled heat pump (GCHP). In order to assess the performance of this type of installation, a computer model composed by two parts has been developed. The Borehole Heat Exchanger (BHE) model is developed in COMSOL Multiphysics, based on numerical methods. Part of the results are fed to the heat pump energy model, developed in MATLAB. A real case study has been used to validate the model: the Faculty of Engineering of La Sapienza University in Latina, undertaking a renewal project for an abandoned part of the building. After the renovation, the building will host a research center on the topic of low-enthalpy geothermal systems. The analysis have demonstrated that the modelled GCHP system can supply a significant share of the energy required from the future research center. This amount of energy can be provided keeping almost stable the thermal balance of the surrounding region in the subsoil, operating in a sustainable way. The range of variation of the ground temperature with respect to the average value is within the limit of 5°C, which is the cap set by the international legislation.
Comparison of isothermal and isoflux g-functions for borehole-heat-exchanger fields
Authors: Naldi C , Zanchini E 
Published: May 2019

Abstract
A new numerical approach to determine the g-function of a borehole field with the boundary condition of uniform temperature and time-constant mean heat flux at the surface of the boreholes is presented. The method is employed to compare the g-functions obtained by this boundary condition with those obtained by the usual condition of uniform and constant heat flux, for a single borehole and for a field of six boreholes placed in two lines. Boreholes with length 150 m, diameter 15 cm, buried depth 1.5 m and mutual distance 7.5 m, for the field, are considered. The results show that the difference between the two kinds of g-functions is less than 1.5 % for a single borehole, while it reaches 8.7 % for the borehole field, at high values of time. Finally, we show that the superposition of the effects of the single boreholes yields correctly the g-function of the field in the case of uniform heat flux, but overestimates the g-function in the case of uniform temperature and constant mean heat flux.
Ventilated pitched roof with forced ventilation and flow homogenizer device: testing and performance assessment
Authors: Ferrari C , Muscio A 
Published: May 2019

Abstract
Ventilated tile roofs are common objects in the construction sector of Italy. A preferred type is characterized by a ventilated air space between the upper tile layer and the roof structure below. The air enters through openings at the gutters level, flows up below sheathing in the air space along the pitch and is finally discharged through openings along the ridge. This setup, which leaves the room below the roof sealed and habitable, allows removing the heat brought by the absorbed solar radiation thanks to the flow that is established by natural ventilation in the air space. However, its actual performance is often weak and also unpredictable due to continuously changing buoyancy forces. Nonetheless, a permanent and adequate flow can be ensured even through a relatively thin air space and for whichever irradiance and wind conditions by forced ventilation: a properly designed fan can provide the desired flow rate by extracting the air after this is collected along the ridge by a manifold. A thorough design and manufacturing of the manifold is needed, however, to avoid a highly inhomogeneous flow, which would follow the easiest path and leave most of the pitch practically unventilated. As an alternative, a throttling shutter parallel to the ridge has been proposed to progressively choke the flow entering the manifold through parallel climbing ducts as the fan is approached, possibly allowing onsite adjustment after installation. In this work the solution, developed by means of a small scale test bed, is illustrated in details and some methods to assess the performance are presented.
Application of RELAP5/Mod3.3 – Fluent coupling codes to CIRCE-HERO
Authors: Forgione N , Angelucci M , Ulissi C , Martelli D , Barone G , Ciolini R , Tarantino M 
Published: May 2019

Abstract
This paper presents the work ongoing at the DICI (Dipartimento di Ingegneria Civile e Industriale) of the University of Pisa on the application of coupled methodology between Fluent CFD code and RELAP5/Mod3.3 system code. In particular, this methodology was applied to the LBE-water heat exchanger HERO, with the aim to analyse the performances of this component. The test section object of this study is installed inside the vessel S100 of the CIRCE facility, built at ENEA Brasimone Research Centre.
In the proposed methodology the CFD code is adopted to simulate the LBE side of the HERO heat exchanger, whereas the secondary side (two-phase flow, water-vapour) is simulated by the STH code. In this procedure, the variables exchanged between the boundaries of the two codes are: the bulk temperature and heat transfer coefficient of the ascending water (in two-phase flow) obtained from RELAP5 and transferred to Fluent code; the wall temperature at the water side surface of the pipes is calculated by Fluent and passed to RELAP5 code.
The coupling procedure was verified by comparing the obtained results with the analogous ones achieved with the RELAP5 stand-alone calculation, proving that the developed coupling methodology is reliable. Further, the coupled simulation allows to obtain more accurate information on the LBE side.
Relative importance of entrained liquid fraction and mass transfer at the interface on pressure drop of annular flows
Authors: Lillo G , Mastrullo R , Mauro A W , Revellin R 
Published: May 2019

Abstract
Fully developed adiabatic two-phase flows are commonly encountered in practice and their modeling is of primary importance for accurate, local calculations of pressure gradients and void fraction for the design of several industrial applications as heat exchangers and long fluid transfer piping. For large void fractions, the entrainment of liquid droplets into the vapor core can have a large effect on the pressure gradients. In this paper starting from theoretical considerations about the modeling of the pressure gradients in an annular two-phase flow, a numerical analysis as well as a discussion are proposed in order to quantify the relative importance of the entrainment on the calculations and to address further experimental studies and models on this topic.
Onset of convective instability within an inclined porous layer with a permeable boundary
Authors: Celli Michele , Barletta Antonio 
Published: May 2019

Abstract
The investigation of the thresholds that identify the onset of convective instability in a fluid saturated porous layer is performed. The layer is inclined with respect to the horizontal and the boundaries are held at different uniform temperatures. The layer is also semi-permeable: one boundary is impermeable and the other one is permeable. This configuration yields a basic state characterised by a single convective cell, with zero mass flow rate, that fades for small inclination becoming completely motionless for the horizontal case. Since the central part of this cell is considered, the basic flow is parallel and the basic temperature profile is dominated by conduction. This basic state is perturbed employing small-amplitude disturbances such that the linear stability analysis can be performed. A Squire-type transformation is applied to reduce the complexity of the problem. A numerical procedure is employed to obtain the critical values of the governing parameters.
Modified Vlasov Equation and Collective Oscillations of Relativistic Radiating Electron Plasma
Authors: de Parga G. Ares , García-Camacho J. F. 
Published: May 2019

Abstract
A Covariant Statistical Mechanics is developed for a system of electrons within the limits of plasma physics. By using the Landau-Lifshitz equation of motion for point charged particles, the phase space reduces to be a seven dimensional space instead of the ten dimensional space proposed by Hakim and Mangeney [J. Math. Phys. 1968, 9, 1, 116]. A modified Vlasov equation is obtained which permits one to deduce a general expression for the dispersion relations. Unlike other works, neither the Special Relativity nor any of the properties of the gauge are used to discard some of the wave modes. Instead, the continuity equation is used as a constraint embedded in the definition of the 4—vector current. This permits to make a mathematical analysis for calculating and discarding the transverse and longitudinal modes for any temperature. An expression for the longitudinal wave modes is deduced for any temperature and wave number. Usually, certain approximations are made to obtain such an expression that matches our result. But in general, without making such approximations, the result differs by a factor. The Landau damping and the damping due to the radiation reaction force are obtained and contrasted at low and high temperature cases. The results are compared with the ones obtained within Magnetohydrodynamics. Moreover, a numerical method is applied in order to compare the dispersion relations obtained with the approximations made. Surprisingly, it is sampled numerically that the dispersion relations are bounded for each temperature and that there is a cut-off for each wave number.
A non-relativistic magnetized vector boson gas at any temperature
Authors: Suárez-González LC. , Quintero Angulo G. , Pérez Martínez A. , Pérez Rojas H. 
Published: May 2019

Abstract
We study the thermodynamic properties of a neutral vector boson gas in presence of a constant magnetic field, by means of a semi-classical approach that allows to introduce the spin in the non-relativistic spectrum of the bosons. Bose-Einstein condensation is obtained and it turns out to depend on all the parameters involved in the problem: temperature, particle density and magnetic field. A spontaneous magnetization appears at low temperature as a consequence of the condensed state. The axial symmetry imposed in the system by the magnetic field presence, splits the pressure in two components, one along and another perpendicular to the magnetic axis. Under certain conditions, the perpendicular pressure becomes negative signaling that the system undergoes a transversal magnetic collapse. The spontaneous magnetization might be useful to model magnetic field production inside compact stars, while the negative pressures imposes certain limits to the temperatures and densities needed inside these objects to support a given magnetic field.
The Effect of Retardation on Galactic Rotation Curves
Authors: Yahalom Asher 
Published: May 2019

Abstract
Galaxies are huge physical systems having dimensions of many tens of thousands of light years. Thus any change at the galactic center will be noticed at the rim only tens of thousands of years later. Those retardation effects seems to be neglected in present day galactic modelling used to calculate rotational velocities of matter in the rims of the galaxy and surrounding gas. The significant differences between the predictions of Newtonian instantaneous action at a distance and observed velocities are usually explained by either assuming dark matter or by modifying the laws of gravity (MOND). In this paper we will show that taking general relativity seriously without neglecting retardation effects one can explain the radial velocities of galactic matter without postulating dark matter.
Relativistic Beaming as a Probe of Stellar and Planetary Masses
Authors: Placek Ben 
Published: May 2019

Abstract
The primary method of extra-solar planet (exoplanet) detection and characterization is through planetary transits. These events occur when a planet is observed to pass in front of it’s host star with respect to the observers line of sight, which causes a small dimming event. Transits alone yield information on the orbital properties such as period, inclination, semi-major axis as well as physical properties such as the planetary radius. With high-precision photometry, a new photometric effect has emerged as a probe of short-period exoplanet masses. This effect is known as relativistic Doppler beaming (or boosting), and has been used to estimate the masses and densities of numerous exoplanets and stars in binary systems. Here, this effect is discussed in detail along with the prospect of utilizing it with next generation space-based telescopes that will be devoted to the detection and characterization of exoplanets. Prospects for the characterization of binary systems will also be examined.