T. Paul

ULTRAHIGH ENERGY COSMIC RAYS: THE STATE OF THE ART BEFORE THE AUGER OBSERVATORY

In this review we discuss the important progress made in recent years towards understanding the experimental data on cosmic rays with energies

The offline software framework of the Pierre Auger Observatory

\agt 10^{19}

What IceCube data tell us about neutrino emission from star-forming galaxies (so far)

eV. We begin with a brief survey of the available data, including a description of the energy spectrum, mass composition, and arrival directions. At this point we also give a short overview of experimental techniques. After that, we introduce the fundamentals of acceleration and propagation in order to discuss the conjectured nearby cosmic ray sources. We then turn to theoretical notions of physics beyond the Standard Model where we consider both exotic primaries and exotic physical laws. Particular attention is given to the role that TeV-scale gravity could play in addressing the origin of the highest energy cosmic rays. In the final part of the review we discuss the potential of future cosmic ray experiments for the discovery of tiny black holes that should be produced in the Earths atmosphere if TeV-scale gravity is realized in Nature.

High energy physics in the atmosphere: Phenomenology of cosmic ray air showers

The Pierre Auger Observatory is designed to unveil the nature and the origins of the highest energy cosmic rays. The large and geographically dispersed collaboration of physicists and the wide-ranging collection of simulation and reconstruction tasks pose some special challenges for the offline analysis software. We have designed and implemented a general purpose framework which allows collaborators to contribute algorithms and sequencing instructions to build up the variety of applications they require. The framework includes machinery to manage these user codes, to organize the abundance of user-contributed configuration files, to facilitate multi-format file handling, and to provide access to event and time-dependent detector information which can reside in various data sources. A number of utilities are also provided, including a novel geometry package which allows manipulation of abstract geometrical objects independent of coordinate system choice. The framework is implemented in C++, and takes advantage of object oriented design and common open source tools, while keeping the user side simple enough for C++ novices to learn in a reasonable time. The distribution system incorporates unit and acceptance testing in order to support rapid development of both the core framework and contributed user code

Extensive air showers with TeV scale quantum gravity

Very recently, the IceCube Collaboration reported a flux of neutrinos in the energy range 50 TeV < E_\nu < 2 PeV, which departs from expectations from atmospheric background at the 5.7\sigma level. This flux is in remarkable agreement with the expected diffuse flux of neutrinos from starburst galaxies, and the 3 highest energy events have uncertainty contours encompassing some of such systems. These events, all of which have well-measured energies above 1 PeV, exhibit shower topologies, for which the angular resolution is about 15^\circ. Due to this angular uncertainty and the a posteriori nature of cuts used in our study it is not possible to assign a robust statistical significance to this association. Using muon tracks, which have angular resolution < 1^\circ, we compute the number of observations required to make a statistically significant statement, and show that in a few years of operation the upgraded IceCube detector should be able to confirm or refute this hypothesis. We also note that double bang topology rates constitute a possible discriminator among various astrophysical sources.

End of the cosmic neutrino energy spectrum

The properties of cosmic rays with energies above 10 6 GeV have to be deduced from the spacetime structure and particle content of the air showers which they initiate. In this review we summarize the phenomenology of these giant air showers. We describe the hadronic interaction models used to extrapolate results from collider data to ultra high energies, and discuss the prospects for insights into forward physics at the LHC. We also describe the main electromagnetic processes that govern the longitudinal shower evolution, as well as the lateral spread of particles. Armed with these two principal shower ingredients and motivation from the underlying physics, we provide an overview of some of the different methods proposed to distinguish primary species. The properties of neutrino interactions and the potential of forthcoming experiments to isolate deeply penetrating showers from baryonic cascades are also discussed. We finally venture into a terra incognita endowed with TeV-scale gravity and explore anomalous neutrino-induced showers.

Weinberg’s Higgs portal confronting recent LUX and LHC results together with upper limits on B + and K + decay into invisibles

One of the possible consequences of the existence of extra degrees of freedom beyond the electroweak scale is the increase of neutrino-nucleon cross sections ({sigma}{sub {nu}N}) beyond standard model predictions. At ultrahigh energies this may allow the existence of neutrino-initiated extensive air showers. In this paper, we examine the most relevant observables of such showers. Our analysis indicates that the future Pierre Auger Observatory could be potentially powerful in probing models with large compact dimensions.

Estimating the contribution of Galactic sources to the diffuse neutrino flux

Abstract There may be a high-energy cutoff of neutrino events in IceCube data. In particular, IceCube does not observe either continuum events above 2 PeV, or the Standard Model Glashow-resonance events expected at 6.3 PeV. There are also no higher energy neutrino signatures in the ANITA and Auger experiments. This absence of high-energy neutrino events motivates a fundamental restriction on neutrino energies above a few PeV. We postulate a simple scenario to terminate the neutrino spectrum that is Lorentz-invariance violating, but with a limiting neutrino velocity that is always smaller than the speed of light. If the limiting velocity of the neutrino applies also to its associated charged lepton, then a significant consequence is that the two-body decay modes of the charged pion are forbidden above two times the maximum neutrino energy, while the radiative decay modes are suppressed at higher energies. Such stabilized pions may serve as cosmic ray primaries.

Using cosmic neutrinos to search for nonperturbative physics at the Pierre Auger Observatory

We discuss a number of experimental constraints on Weinbergs Higgs portal model. In this framework, the standard model (SM) particle spectrum is extended to include one complex scalar field S and one Dirac fermion \psi. These new fields are singlets under the SM gauge group and are charged under a global U(1) symmetry. Breaking of this U(1) symmetry results in a massless Goldstone boson \alpha and a massive CP-even scalar r, and splits the Dirac fermion into two new mass-eigenstates \psi_\pm, corresponding to Majorana fermions. The interest on such a minimal SM extension is twofold. On the one hand, if the Goldstone bosons are in thermal equilibrium with SM particles until the era of muon annihilation their contribution to the effective number of neutrino species can explain the hints from cosmological observations of extra relativistic degrees of freedom at the epoch of last scattering. On the other hand, the lightest Majorana fermion \psi_- provides a plausible dark matter candidate. Mixing of r with the Higgs doublet \phi is characterized by the mass of hidden scalar m_h and the mixing angle \theta. We constrain this parameter space using a variety of experimental data, including heavy meson decays with missing energy, the invisible Higgs width, and direct dark matter searches. We show that different experimental results compress the allowed parameter space in complementary ways, covering a large range of \psi_- masses (5 GeV \alt m_- \alt 100 GeV). Though current results narrow the parameter space significantly (for the mass range of interest, \theta \alt 10^{-3} to 10^{-4}), there is still room for discovery (\alpha decoupling at the muon annihilation era requires \theta \agt 10^{-5} to 10^{-4}). In the near future, measurements from ATLAS, CMS, LHCb, NA62, XENON1T, LUX, and CDMSlite will probe nearly the full parameter space.

Radiative tau lepton pair production as a probe of anomalous electromagnetic couplings of the tau

Motivated by recent IceCube observations we re-examine the idea that microquasars are high energy neutrino emitters. By stretching to the maximum the parameters of the Fermi engine we show that the nearby high-mass X-ray binary LS 5039 could accelerate protons up to above about 20 PeV. These highly relativistic protons could subsequently interact with the plasma producing neutrinos up to the maximum observed energies. After that we adopt the spatial density distribution of high-mass X-ray binaries obtained from the deep INTEGRAL Galactic plane survey and we assume LS 5039 typifies the microquasar population to demonstrate that these powerful compact sources could provide a dominant contribution to the di use neutrino flux recently observed by IceCube.