Introduction to discoverology
Can we increase chances for a scientific breakthrough by get trained in discovery-oriented thinking?
physics.pop-ph↗
arXiv subjects
Piotr Homola
Publications and source records attributed to Piotr Homola.
Limits on beyond standard model messengers as ultra high energy cosmic rays
Up to date, there is no consensus regarding the origin of ultra-high energy cosmic rays (UHECR) beyond the Greisen--Zatsepin--Kuzmin (GZK) limit. In order for these UHECRs to reach the Earth, an extremely suppressed interaction between them and the cosmic microwave background (CMB) is required, which is impossible for standard model (SM) particles, except neutrinos. In this letter, we present constraints on the parameter space of models involving axion-like particles and dark photons, as candidates for UHECRs, by assuming that these particles can traverse the visible Universe without decaying. In the case of axion-like particles, the constraints are tighter than those given in previous works. We present for the first time constraints on the parameter space of dark photon models, by considering their kinetic term mixing with SM photons.
astro-ph.HE↗
Asymmetry of the angular distribution of Cherenkov photons of extensive air showers induced by the geomagnetic field
The angular distribution of Cherenkov light in an air shower is closely linked to that of the shower electrons and positrons. As charged particles in extensive air showers are deflected by the magnetic field of the Earth, a deformation of the angular distribution of the Cherenkov light, that would be approximately symmetric about the shower axis if no magnetic field were present, is expected. In this work we study the variation of the Cherenkov light distribution as a function of the azimuth angle in the plane perpendicular to shower axis. It is found that the asymmetry induced by the geomagnetic field is most significant for early stages of shower evolution and for showers arriving almost perpendicular to the vector of the local geomagnetic field. Furthermore, it is shown that ignoring the azimuthal asymmetry of Cherenkov light might lead to a significant under- or overestimation of the Cherenkov light signal especially at sites where the local geomagnetic field is strong. Based on CORSIKA simulations, the azimuthal distribution of Cherenkov light is parametrized in dependence on the magnetic field component perpendicular to the shower axis and the local air density. This parametrization provides an efficient approximation for estimating the asymmetry of the Cherenkov light distribution for shower simulation and reconstruction in cosmic ray and gamma-ray experiments in which the Cherenkov signal of showers with energies above 10^14 eV is observed.
astro-ph.IM↗
A method to calibrate the absolute energy scale of air showers with ultra-high energy photons
Calibrating the absolute energy scale of air showers initiated by ultra-high energy cosmic rays is an important experimental issue. Currently, the corresponding systematic uncertainty amounts to 14-21% using the fluorescence technique. Here we describe a new, independent method which can be applied if ultra-high energy photons are observed. While such photon-initiated showers have not yet been identified, the capabilities of present and future cosmic-ray detectors may allow their discovery. The method makes use of the geomagnetic conversion of UHE photons (preshower effect), which significantly affects the subsequent longitudinal shower development. The conversion probability depends on photon energy and can be calculated accurately by QED. The comparison of the observed fraction of converted photon events to the expected one allows the determination of the absolute energy scale of the observed photon air showers and, thus, an energy calibration of the air shower experiment. We provide details of the method and estimate the accuracy that can be reached as a function of the number of observed photon showers. Already a very small number of UHE photons may help to test and fix the absolute energy scale.
astro-ph.IM↗
Simulation of ultra-high energy photon propagation with PRESHOWER 2.0
In this paper we describe a new release of the PRESHOWER program, a tool for Monte Carlo simulation of propagation of ultra-high energy photons in the magnetic field of the Earth. The PRESHOWER program is designed to calculate magnetic pair production and bremsstrahlung and should be used together with other programs to simulate extensive air showers induced by photons. The main new features of the PRESHOWER code include a much faster algorithm applied in the procedures of simulating the processes of gamma conversion and bremsstrahlung, update of the geomagnetic field model, and a minor correction. The new simulation procedure increases the flexibility of the code so that it can also be applied to other magnetic field configurations such as, for example, encountered in the vicinity of the sun or neutron stars.
astro-ph.IM↗
Search for ultra-high energy photons using air showers
The observation of photons with energies above 10^18 eV would open a new window in cosmic-ray research, with possible impact on astrophysics, particle physics, cosmology and fundamental physics. Current and planned air shower experiments, particularly the Pierre Auger Observatory, offer an unprecedented opportunity to search for such photons and to complement efforts of multimessenger observations of the universe. We summarize motivation, achievements, and prospects of the search for ultra-high energy photons.
astro-ph↗