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Electroweak effects in process
No full textElectroweak radiative corrections to the cross section of the process are considered. The complete one-loop electroweak radiative corrections are evaluated with the help of the SANC system. Higher-order contributions of the initial state radiation are computed in the QED structure function formalism. Numerical results are produced by a new version of the ReneSANCe event generator and MCSANCee integrator for the conditions of future electron-positron colliders. The resulting theoretical uncertainty in the description of this process is estimated
Hybrid neutron stars in the mass-radius diagram
No full textWe present a systematic investigation of the possible locations for the special point (SP), a unique feature of hybrid neutron stars in the mass-radius. The study is performed within the two-phase approach where the high-density (quark matter) phase is described by the constant-sound-speed (CSS) equation of state (EoS) and the nuclear matter phase around saturation density is varied from very soft (APR) to stiff (DD2 with excluded nucleon volume. Different construction schemes for the deconfinement transition are applied: Maxwell construction, mixed phase construction and parabolic interpolation. We demonstrate for the first time that the SP is invariant not only against changing the nuclear matter EoS, but also against variation of the construction schemes for the phase transition. Since the SP serves as a proxy for the maximum mass and accessible radii of massive hybrid stars, we draw conclusions for the limiting masses and radii of hybrid neutron stars
TMDlib2 and TMDplotter: a platform for 3D hadron structure studies
No full textA common library, TMDlib2, for Transverse-Momentum-Dependent distributions (TMDs) and unintegrated parton distributions (uPDFs) is described, which allows for easy access of commonly used TMDs and uPDFs, providing a three-dimensional (3D) picture of the partonic structure of hadrons. The tool TMDplotter allows for web-based plotting of distributions implemented in TMDlib2, together with collinear pdfs as available in LHAPDF
Si(p,γ)P direct proton capture by means of the asymptotic normalization coefficients method for mirror nuclei
No full textThe Si26(p,γ)P27 reaction might be relevant in understanding the Si26 depletion and Al26 production in stars. The asymptotic normalization coefficients (ANC) for the Si26(p,γ)P27 reaction were extracted earlier from the reanalysis of Mg26(d,p)Mg27 and Mg26(t,d)Mg27 reactions, in which the deduced ANC's show significant discrepancies. In this work, a dedicated (d,p) measurement is presented: the ANC for the Mg27→Mg26+n virtual decay is deduced from the Mg26(d,p)Mg27 reaction populating the ground and the first excited state of Mg27 using the distorted wave Born approximation (DWBA). The charge symmetry properties for mirror nuclei have been used to calculate the ANC for the direct capture Si26+p→P27 populating the ground state of P27. By means of the same formalism, the Γp width for the first excited state has also been deduced. The reaction rate is also updated using recent values for the Γγ/Γp ratio measured by [Sun , Phys. Rev. C 99, 064312 (2019)2469-998510.1103/PhysRevC.99.064312; Sun , Phys. Lett. B 802, 135213 (2020)PYLBAJ0370-269310.1016/j.physletb.2020.135213]
Determination of Zenith Angle Dependence of Incoherent Cosmic Ray Muon Flux Using Smartphones of the CREDO Project
No full textThe Cosmic-Ray Extremely Distributed Observatory (CREDO) was established to detect and study ultra high-energy cosmic ray particles. In addition to making use of traditional methods for finding rare and extended cosmic ray events such as professional-grade Extensive Air Shower (EAS) arrays, as well as educational ‘class-room’ detectors, CREDO also makes use of cameras in smartphones as particle detectors. Beyond the primary scientific goal of the CREDO project, to detect Cosmic Ray Ensembles, is the equally important educational goal of the project. To use smartphones for EAS detection, it is necessary to demonstrate that they are capable of effectively registering relativistic charged particles. In this article, we show that the events recorded in the CREDO project database are indeed tracing incoherent cosmic ray muons. The specific observed distribution of zenith angle of charged particle direction corresponds to that expected for muons. It is difficult, if not impossible, to imagine different mechanisms leading to such a distribution, and we believe it clearly demonstrates the suitability of smartphone-based detectors in supporting the more traditional cosmic ray detectors
SU(2|1) chiral superfields and spinning models
No full textWe consider the coupling of dynamical and semi-dynamical (spin) multiplets described by superfields living on the generalized SU(2|1), d=1 chiral superspace. The interaction term of both multiplets is constructed as a superpotential term, where the dynamical multiplet is defined as a chiral multiplet , while the semi-dynamical multiplet is associated with a mirror multiplet
Formation of He in the Be(π, p)X and B(π, pp)X Stopped Pion Absorption Reactions
No full textThe structure of levels of the He heavy helium isotope has been studied in the Be and B stopped pion absorption reactions. Measurements have been performed with a two-arm multilayer semiconductor spectrometer at the LANL. Indications to the existence of a soft dipole mode at the excitation energy MeV have been obtained. A state with a high excitation energy of 12.2(5) MeV has been observed for the first time
Parameter mapping between the microscopic nonlocal Nambu-Jona-Lasinio and constant-sound-speed models
No full textA covariant nonlocal Nambu-Jona-Lasinio (nlNJL) model, used to describe the color superconducting quark matter phase in hybrid neutron stars, is parametrized with two free parameters, the dimensionless vector and diquark coupling strengths and . Changing the values of these parameters results in different equations of state (EoS) with varying stiffness. On the other hand, the constant-sound-speed (CSS) model is a frequently used, simple quark matter equation of state with three parameters: the slope parameter , the speed of sound and the bag pressure . We show that the CSS model EoS provides an excellent fit to that of the nlNJL model. This work provides a simple functional form for the mapping between the parameter spaces of these two models, i.e. the and parameter sets. These results allow for a simplified description of the quark matter phase in neutron stars and for an interpretation of hybrid neutron star phenomenology in terms of parameters of a Lagrangian quark matter model
Induced Surface and Curvature Tensions Equation of State of Hadrons with Relativistic Excluded Volumes and its Relation to Morphological Thermodynamics
No full textAn analytical formula that accurately accounts for the Lorentz contraction of the excluded volume of two relativistic hadrons with hard-core repulsion is worked out. Using the obtained expression we heuristically derive the equation of state of Boltzmann particles with relativistic excluded volumes in terms of system pressure and its surface and curvature tension coefficients. The behavior of effective excluded volumes of lightest baryons and mesons is studied at very high temperatures (particle number densities) and for very large values of degeneracy factors. Several parameterizations of the obtained equation of state demonstrate a universal asymptotics of the effective excluded volume at high particle number densities. It is peculiar, that the found maximal packing fraction of Lorentz contracted particles is very close to the dense packing limit of classical hard spheres of same radius . We show that the developed equation of state is the grand canonical formulation of the morphological thermodynamics approach applied to Lorentz contracted rigid spheres