The Randall-Sundrum model with a small curvature is considered in which five-dimensional Planck scale lies in the TeV region, and a spectrum of Kaluza-Klein gravitons reminds that in one flat extra dimension. The cross sections for interactions of ultra-high energy cosmic neutrinos with nucleons are calculated. It is shown that effects related with massive graviton excitations can be detected in deeply penetrating inclined air showers induced by these neutrinos. The expected number of air showers at the Auger Observatory is estimated as a function of two parameters of the model.
The increasing cosmic ray statistics collected by present experiments and the future prospects with new large arrays demand accurate calculations of the extensive air shower parameters. The energy of the primary particle is estimated by ground arrays fitting a lateral distribution function (LDF) to the particle densities at a given observing level. However, the lack of appropriate parameterization for these distributions, able to reproduce the data collected from all arrival directions, makes it difficult the experimental analysis. Starting from analytical LDF for vertical showers we study the…
We propose to extract the charge information of high energy muons in very inclined extensive air showers by analyzing their relative lateral positions in the shower transverse plane. We calculate the muon lateral deviation under the geomagnetic field and compare it to dispersive deviations from other causes. By our criterion of resolvability, positive and negative muons with energies above $10^4$ GeV will be clearly separated into two lobes if the shower zenith angle is larger than $70^\circ$. Thus we suggest a possible approach to measure the $μ^+ / μ^-$ ratio for high energy muons.
A report on the characteristics of ultra-high energy air showers simulated with the AIRES program is presented. The AIRES system includes a fast simulating program which is an improved version of the well-known MOCCA program. The AIRES algorithms are briefly described and a series of results coming from the simulations are analyzed.
Most calculations of air shower development have been based on the Bethe-Heitler cross sections for bremsstrahlung and pair production. However, for energetic enough particles, a number of different external factors can reduce these cross sections drastically, slowing shower development and lengthening the showers. Four mechanisms that can suppress bremsstrahlung and pair production cross sections are discussed, and their effect on extremely high energy air showers considered. Besides lengthening the showers, these mechanisms greatly increase the importance of fluctuations in shower developmen…
A report on the characteristics of ultra-high energy air showers simulated with the current version of the AIRES program is presented. The AIRES system includes a fast simulating program, originally designed on the basis of the well-known MOCCA program, and progressively improved and tested. The AIRES algorithms are briefly described and some results coming from the simulations are analyzed.
The objective of this work is to report on the modifications in air shower development due to muon bremsstrahlung and muonic pair production. In order to do that we have implemented new muon bremsstrahlung and muonic pair production procedures in the AIRES air shower simulation system, and have used it to simulate ultra high energy showers in different conditions. The influence of the mentioned processes in the global development of the air shower is important for primary particles of large zenith angles, while they do not introduce significant changes in the position of the shower maximum.
A procedure is suggested for systematically narrowing the choice of possible primaries for (UHECR) air showers with energies beyond the Greisen-Zatsepin-Kuz'min cut-off of $4 \times 10^{19} eV$.
Some general properties of extensive air showers are discussed. The main focus is put on the longitudinal development, in particular the energy flow, and on the lateral distribution of different air shower components. The intention of the paper is to provide a basic introduction to the subject rather than a comprehensive review.
We discuss air shower simulations based on the EPOS hadronic interaction model. A remarkable feature is the fact that the number of produced muons is considerably larger compared to other interaction models. We show that this is due to an improved treatment of baryon-antibaryon production.
At high energy, cosmic rays can only be studied by measuring the extensive air showers they produce in the atmosphere of the Earth. Although the main features of air showers can be understood within a simple model of successive interactions, detailed simulations and a realistic description of particle production are needed to calculate observables relevant to air shower experiments. Currently hadronic interaction models are the main source of uncertainty of such simulations. We will study the effect of using different hadronic models available in CORSIKA and CONEX on extensive air shower predi…
We assess the capabilities of a ground-based gamma-ray observatory to detect astrophysical neutrinos with energies in the $100\,{\rm TeV}$ to $100\,{\rm PeV}$ range. The identification of these events would be done through the measurement of very inclined extensive air showers induced by downward-going and upward-going neutrinos. The discrimination of neutrino-induced showers in the overwhelming cosmic-ray background is achieved by analysing the balance of the total electromagnetic and muonic signals of the shower at the ground. We demonstrate that a ${\rm km^2}$-scale wide field-of-view groun…
Amplified Tau-airshower at horizons may well open a novel powerful windows, at PeV-EeV energy, to Neutrino Astronomy. Neutrino induced air-showering astronomy rise because of neutrino masses, their mixing and the consequent replenishment of tau flavor during neutrino flight into spaces; Tau-Air-Showers escaping the Earth are the main traces amplified by its millions muon, billions gamma and thousand billions photon secondaries. Earth edges and its sharp shadows is the huge beam-dump detector for UHE neutrino and the almost noise-free screen for tau air-showers (as well as for PeVs anti-neutrin…
We review some of the properties of extensive cosmic ray air showers and describe a simple model of the radio-frequency radiation generated by shower electrons and positrons as they bend in the Earth's magnetic field. We perform simulations by calculating the trajectory and radiation of a few thousand charged shower particles. The results are then transformed to predict the strength and polarization of the electromagnetic radiation emitted by the whole shower.
The objective of this work is to report on the influence of muon interactions on the development of air showers initiated by astroparticles. We make a comparative study of the different theoretical approaches to muon bremsstrahlung and muonic pair production interactions. A detailed algorithm that includes all the relevant characteristics of such processes has been implemented in the AIRES air shower simulation system. We have simulated ultra high energy showers in different conditions in order to measure the influence of these muonic electromagnetic interactions. We have found that during the…
We present a macroscopic calculation of coherent electro-magnetic radiation from air showers initiated by ultra-high energy cosmic rays, based on currents obtained from Monte Carlo simulations of air showers in a realistic geo-magnetic field. We can clearly relate the time signal to the time dependence of the currents. We find that the the most important contribution to the pulse is related to the time variation of the currents. For showers forming a sufficiently large angle with the magnetic field, the contribution due to the currents induced by the geo-magnetic field is dominant, but neither…
The AIRES (AIR-shower Extended Simulations) system is a set of programs and subroutines to realistically simulate particle showers produced after the incidence of high energy cosmic rays on the Earth's atmosphere, and to manage all the related output data. The current version includes a series of improvements with respect to previous releases that are explained in detail in this manual and/or the web site aires.fisica.unlp.edu.ar from where the software can be downloaded. Among such improvements, it is worth mentioning: (i) High energy hadronic collisions can be simulated usign the the well-kn…
The suggestion is made that air showers with energies beyond the Greisen-Zatsepin-Kuz'min spectral cut-off may have primary vertices some 6 km lower in height than those of proton initiated showers with energies below the GZK cut-off. This estimate is based on the assumption that post-GZK showers are due to neutrinos having acquired strong interactions from generation-changing dual gluon exchange as recently proposed.
We present an introductory lecture on general features of cosmic rays, for non-experts, and some recent developments concerning cascade equations for air shower developments.
An analysis of the differences introduced by the hadronic interaction event generators during the development of the showers is presented. We have generated proton and nuclei induced air showers with energies up to $10^{20.5}$ eV, ``herded up'' by the code aires + sibyll/ qgsjet. The most relevant observables are taken into account for the comparison.
Cerenkov Telescopes and Scintillators set on a Crown-like arrays facing the Horizons may reveal far Cosmic Rays Showers, nearer Anti-Neutrino-Electron + Electron --> W- shower in air and upgoing Tau Neutrino + N--> tau + X, --> Shower, Earth-Skimming tau air-showers. Even UHE SUSY Chi + e--> Selectron--> Chi + e at tens PeVs-EeV energy may blaze at Horizons, as anti-neutrino electron at Glashow peak - Burst shower. We show first estimate on down and up-going Horizontal Showers traces for present and future Magic-like Crown Arrays and their correlated Scintillator-like twin Crown Arrays. The on…
The existence of extra degrees of freedom beyond the electroweak scale may allow the formation of black holes in nearly horizontal neutrino air showers. In this paper we examine the average properties of the light descendants of these black holes. Our analysis indicates that black hole decay gives rise to deeply penetrating showers with an electromagnetic component which differs substantially from that in conventional neutrino interactions, allowing a good characterization of the phenomenon against background. Naturally occurring black holes in horizontal neutrino showers could be detected and…
Whereas air shower simulations are very valuable tools for interpreting cosmic ray data, there is a long standing problem: is seems to be impossible to accommodate at the same time the longitudinal development of air showers and the number of muons measured at ground. Using a new hadronic interaction model (EPOS) in air shower simulations produces considerably more muons, in agreement with results from the HiRes-MIA experiment. We find that this is mainly due to a better description of baryon-antibaryon production in hadronic interactions. This is a new aspect of air shower physics which has n…
We discuss the relation between remnant fragmentation in inelastic high-energy hadronic interactions and muon production in extensive cosmic ray air showers. Using a newly developed tool, a simple and flexible hadronic event generator, we analyze the forward region of hadronic interactions. We show that measurements of the Feynman-x distribution in the beam fragmentation region at LHCf will be key to understanding muon production in air showers quantitatively.
The discovery of the Higgs boson marks a key ingredient to establish the electroweak structure of the Standard Model. Its non-abelian gauge structure gives rise to, yet unobserved, non-perturbative baryon and lepton number violating processes. We propose to use cosmic ray air showers, as measured at the Pierre Auger Observatory, to set a limit on the hadronic production cross section of sphalerons. We identify several observables to discriminate between sphaleron and QCD induced air showers.
Since recent RHIC data and the development of new theories for small x physics, a new interest appeared for forward physics. At LHC, a correct description of multiple parton interactions will be crucial to understand all the results. On the other hand, forward particle production and multiple interactions are the key points of air shower development. That's why air shower measurements done by precise experiments like KASCADE can help to understand high energy interactions, using hadronic models which are able to reproduce both accelerator and air shower data. In the framework of the EPOS model…
We demonstrate that the shower-to-shower fluctuations of the muon content of extensive air showers correlate with the fluctuations of a variable of the first interaction of Ultra High Energy Cosmic Rays, which is computed from the fraction of energy carried by the hadrons that sustain the hadronic cascade. The influence of subsequent stages of the shower development is found to play a sub-dominant role. As a consequence, the shower-to-shower distribution of the muon content is a direct probe of the hadron energy spectrum of interactions beyond 100 TeV center of mass energies.
It has been proposed recently that, within the framework of split Supersymmetry, long lived gluinos generated in astrophysical sources could be detected using the signatures of the air showers they produce, thus providing a lower bound for their lifetime and for the scale of SUSY breaking. We present the longitudinal profile and lateral spread of $G$-hadron induced extensive air showers and consider the possibility of measuring them with a detector with the characteristics of the Pierre Auger Observatory.
Hadronic cross sections at ultra-high energy have a significant impact on the development of extensive air shower cascades. Therefore the interpretation of air shower data depends critically on hadronic interaction models that extrapolate the cross section from accelerator measurements to the highest cosmic ray energies. We discuss how extreme scenarios of cross section extrapolations can affect the interpretation of air shower data. We find that the theoretical uncertainty of the extrapolated proton-air cross section at ultra-high energies is much larger than suggested by the existing spread …
The Sydney University Giant Air-shower Recorder (SUGAR) measured the muon component of extensive air showers with a unique array of muon detectors. The SUGAR data allow us to reconstruct the empirical dependence of muon density on the distance from the axis of the shower, the lateral distribution function (LDF). We compare the shape of this function with the predictions of hadronic-interaction models, QGSJET-II-04 and EPOS-LHC, in the energy range 10^17.6 - 10^18.6 eV. We find a difference between the observed data and the simulation: the observed muon density falls faster with the increased c…
We note that the new unitarity regime when scattering amplitude goes beyond the black disc limit (antishadowing) could help in the explanation of the regularities such as knee in the energy spectrum, existence of penetrating and long-flying particles and other features observed in the measurements of the extensive air showers which originate from cosmic particles interactions with the atmosphere.
In this talk we present a possible explanation of the presence of high muon multiplicity events registered recenty by CERN ALICE experiment in its dedicated cosmic ray run.
Very high energy cosmic rays are typically studied by measuring extensive air showers formed by secondary particles produced in collisions with air nuclei. The indirect character of the measurement makes the physics interpretation of cosmic ray data strongly dependent on simulations of multiparticle production in showers. In April 2002 about 50 physicists met in Karlsruhe to discuss various aspects of hadronic multiparticle production with the aim of intensifying the interaction between high energy physics and cosmic ray groups. Current and upcoming possibilities at accelerators for measuring …
We present a comprehensive study of TeV black hole events in Earth's atmosphere originated by cosmic rays of very high energy. An advanced fortran Monte Carlo code is developed and used to simulate black hole extensive air showers from ultrahigh-energy neutrino-nucleon interactions. We investigate the characteristics of these events, compare the black hole air showers to standard model air showers, and test different theoretical and phenomenological models of black hole formation and evolution. The main features of black hole air showers are found to be independent of the model considered. No …
Studies of the nature of cosmic ray particles at the highest energies are based on the measurement of extensive air showers. Most cosmic ray properties can therefore only be obtained from the interpretation of air shower data and are thus depending on predictions of hadronic interaction models at ultra-high energies. We discuss different scenarios of model extrapolations from accelerator data to air shower energies and investigate their impact on the corresponding air shower predictions. To explore the effect of different extrapolations by hadronic interaction models we developed an ad hoc mod…
We find that the ratio r_{mu e} of the muon to the electromagnetic component of an extended air shower at the ground level provides an indirect measure of the depth X_{max} of the shower maximum. This result, obtained with the air-shower code AIRES, is independent of the hadronic model used in the simulation. We show that the value of r_{mu e} in a particular shower discriminates its proton or iron nature with a 98% efficiency. We also show that the eventual production of forward heavy quarks inside the shower may introduce anomalous values of r_{mu e} in isolated events.
The generalized solution for the warp factor of the Randall-Sundrum metric is presented which is symmetric with respect to both branes and explicitly periodic in extra variable. Given that the curvature of the 5-dimensional space-time is small, the expected rate of neutrino-induced inclined events at the Surface Detector of the Pierre Auger Observatory is calculated. Both the "downward-going" (DG) and "Earth-skimming" (ES) neutrinos are considered. By comparing the expected event rate with the recent Auger data on searching for neutrino candidates, the lower bound on the fundamental gravity sc…
A simulation study of the energy released by extensive air showers in the form of MHz radiation is performed using the CoREAS simulation code. We develop an efficient method to extract this radiation energy from air-shower simulations. We determine the longitudinal profile of the radiation energy release and compare it to the longitudinal profile of the energy deposit by the electromagnetic component of the air shower. We find that the radiation energy corrected for the geometric dependence of the geomagnetic emission scales quadratically with the energy in the electromagnetic component of the…
In this article we identify the key elements that govern the propagation of muons from the production in extensive air showers to ground. We describe a model based on simple assumptions that propagates the muons starting from the few relevant distributions at production. We compare the results to the ground distributions given by a full air shower Monte Carlo. This study is motivated by the need of modeling the muon component in extensive air showers with the goal of experimentally reconstructing their distributions at production, which act as a footprint of the hadronic cascade.
Extensive Air Showers are complex macroscopic objects initiated by single ultra-high energy particles. They are the result of millions of high energy reactions in the atmosphere and can be described as the superposition of hadronic and electromagnetic cascades. The hadronic cascade is the air shower backbone, and it is mainly made of pions. Decays of neutral pions initiate electromagnetic cascades, while the decays of charged pions produce muons which leave the hadronic core and travel many kilometers almost unaffected. Muons are smoking guns of the hadronic cascade: the energy, transverse mom…
We present a microscopic computation of the radio emission from air showers initiated by ultra-high energy cosmic rays in the atmosphere. The strategy adopted is to compute each secondary particle contribution of the electromagnetic component and to construct the total signal at any location. SELFAS2 is a code which doesn't rely on air shower generators like AIRES or CORSIKA and it is based on the concept of air shower universality which makes it completely autonomous. Each positron and electron of the air shower is generated randomly following relevant distributions and tracking them along th…
In the sub-TeV regime, the most widely used hadronic interaction models disagree significantly in their predictions of particle spectra from cosmic ray induced air showers. We investigate the nature and impact of model uncertainties, focussing on air shower primaries with energies around the transition between high and low energy hadronic interaction models, where the dissimilarities are largest and which constitute the bulk of the interactions in air showers.
We study the role new gauge interactions in extensions of the standard model play in air showers initiated by ultrahigh-energy cosmic rays. Hadron-hadron events remain dominated by quantum chromodynamics, while projectiles and/or targets from beyond the standard model permit us to see qualitative differences arising due to the new interactions.
Double Extensive Air Showers and aligned events were discovered at energies E {\gtsim} 1016 eV over fourth century back. But up to now there is no sufficiently identical explanation of their nature. In this paper it is expected that both types of events are the result of breakup of the string formed in the collisions of super high energy particles.
The Sydney University Giant Air-shower Recorder (SUGAR) measured the energy spectrum of ultra-high-energy cosmic rays reconstructed from muon-detector readings, while the Pierre Auger Observatory, looking at the same Southern sky, uses the calorimetric fluorescence method for the same purpose. Comparison of their two spectra allows us to reconstruct the empirical dependence of the number of muons in the shower on the primary energy for energies between $10^{17}$ and $10^{18.5}$ eV. We compare this dependence with the predictions of hadronic interaction models \mbox{QGSJET-II-04} and \mbox{EPOS…
In extensive air shower experiments, the number of muons crossing a detector at a given position, as well as their arrival time, arrival direction, and energy, are determined by a more fundamental 3-dimensional distribution linked to the hadronic core of the shower. Muons are produced high up in the atmosphere after the decay of mesons in the hadronic cascade. The distributions of production depth, energy, and transverse momentum of muons are enough to fully predict the muon component of air showers in any particular observational condition. By using air-shower simulations with the state-of-th…
Inspired by recent astrophysical observations of leptonic excesses measured by satellite experiments, we consider the impact of some general models of the dark sector on the muon production in extensive air showers. We present a compact approximative expression for the bremsstrahlung of a massive photon from an electron and use it within Monte Carlo simulations to estimate the amount of weakly interacting photon-like massive particles that could be produced in an extensive air shower. We find that the resulting muon production is by many orders of magnitude below the average muon count in a sh…
Forward hadron production in proton-air collisions above LHC energies through the fluctuations of extensive air showers
Departamento de Física, Instituto Superior Técnico (IST), Universidade de Lisboa（里斯本大学高等理工学院物理系）；Laboratório de Instrumentação e Física Experimental de Partículas (LIP)（粒子实验与仪器实验室）；Technische Universität Dortmund（多特蒙德工业大学）
The understanding of the basic properties of the ultra - high energy extensive air showers is strongly dependent on the description of the hadronic interactions in a energy range beyond that probed by the LHC. One of the uncertainties present in the modeling of the air showers is the treatment of diffractive interactions, which are dominated by non - perturbative physics and usually described by phenomenological models. These interactions are expect to affect the development of the air showers, since they provide a way of transporting substantial amounts of energy deep in the atmosphere, modif…
