We analyze macroscopic effects of TeV-scale black holes, such as could possibly be produced at the LHC, in what is regarded as an extremely hypothetical scenario in which they are stable and, if trapped inside Earth, begin to accrete matter. We examine a wide variety of TeV-scale gravity scenarios, basing the resulting accretion models on first-principles, basic, and well-tested physical laws. These scenarios fall into two classes, depending on whether accretion could have any macroscopic effect on the Earth at times shorter than the Sun's natural lifetime. We argue that cases with such effect at shorter times than the solar lifetime are ruled out, since in these scenarios black holes produced by cosmic rays impinging on much denser white dwarfs and neutron stars would then catalyze their decay on timescales incompatible with their known lifetimes. We also comment on relevant lifetimes for astronomical objects that capture primordial black holes. In short, this study finds no basis for concerns that TeV-scale black holes from the LHC could pose a risk to Earth on time scales shorter than the Earth's natural lifetime. Indeed, conservative arguments based on detailed calculations and the best-available scientific knowledge, including solid astronomical data, conclude, from multiple perspectives, that there is no risk of any significance whatsoever from such black holes.
We study the phenomenology of TeV-scale black holes predicted in theories with large extra dimensions, under the further assumption that they are absolutely stable. Our goal is to present an exhaustive analysis of safety of the proposed 100 TeV collider, as it was done in the case of the LHC. We consider the theories with different number of extra dimensions and identify those for which a possible accretion to macroscopic size would have timescales shorter than the lifetime of the Solar system. We calculate the cross sections of the black hole production at the proposed 100 TeV collider, the f…
Neutrinos with energy greater than GeV are copiously produced in the p(A,p) interactions occurring in several astrophysical sites such as (i) the earth atmosphere, (ii) our galactic plane as well as in (iii) the galaxy clusters. A comparison of the tau and mu neutrino flux in the presence of neutrino oscillations from these three representative astrophysical sites is presented. It is pointed out that the non-atmospheric tau neutrino flux starts dominating over the downward going atmospheric tau neutrino flux for neutrino energy E as low as 10 GeV. This energy value is much lower than the energ…
Measuring neutrino mixing above 1 TeV with astrophysical neutrinos
Niels Bohr International Academy, Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔国际学院、尼尔斯·玻尔研究所）；Queen’s University（女王大学）；Arthur B. McDonald Canadian Astroparticle Physics Research Institute（阿瑟·B·麦克唐纳加拿大高能天体物理研究所）；Perimeter Institute for Theoretical Physics（理论物理前沿研究所）；Simon Fraser University（西蒙菲莎大学）；Universitat de València-CSIC（瓦伦西亚大学-西班牙国家科学研究委员会）
Astrophysical bounds on the high-energy evolution of neutrino mixing
Niels Bohr International Academy, Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯玻尔国际学院、尼尔斯玻尔研究所）；Department of Physics, Simon Fraser University（西蒙菲莎大学物理系）；Arthur B. McDonald Canadian Astroparticle Physics Research Institute（阿瑟·B·麦克唐纳加拿大高能粒子物理研究所）；Departament de Física Teórica and IFIC, Universitat de València-CSIC（瓦伦西亚大学-西班牙国家研究委员会理论物理系及IFIC研究所）
Ultra-high energy cosmic neutrinos are incisive probes of both astrophysical sources and new TeV-scale physics. Such neutrinos would create extensive air showers deep in the atmosphere. The absence of such showers implies upper limits on incoming neutrino fluxes and cross sections. Combining the exposures of AGASA, the largest existing ground array, with the exposure of the Fly's Eye fluorescence detector integrated over all its operating epochs, we derive 95% CL bounds that substantially improve existing limits. We begin with model-independent bounds on astrophysical fluxes, assuming standard…
The Sun albedo of cosmic rays at GeVs energy has been discovered recently by FERMI satellite. They are traces of atmospheric CR hitting solar atmosphere and reflecting skimming gamma photons. Even if relevant for astrophysics, as being trace of atmospheric solar Cosmic Ray noises they cannot offer any signal of neutrino astronomy. On the contrary the Moon, with no atmosphere, may become soon a novel filtering calorimeter and an amplifier of energetic muon astronomical neutrinos (at TeV up to hundred TeV energy); these lepton tracks leave an imprint in their beta decay while in flight to Earth.…
The number of events observed in neutrino telescopes depends on the neutrino fluxes in the Earth, their absorption while crossing the Earth and their interaction in the detector. In this paper, we investigate the impact of the QCD dynamics at high energies on the energy dependence of the average inelasticity and angular dependence of the absorption probability during the neutrino propagation through the Earth, as well in the determination of the properties of the incident astrophysical neutrino flux. Moreover, the number of events at the IceCube and IceCube - Gen2 are estimated considering dif…
Pions, like nucleons, are composed primarily of up and down quarks and gluons. Constraints on spin-independent Lorentz violation in the proton, neutron, and pion sectors translate into bounds on Lorentz violation for the fundamental fields. The best bounds on pion Lorentz violation come from astrophysical measurements. The absence of the absorption process gamma --> pi^(+) + pi^(-) for up to 50 TeV photons constrains the possibility that pions' maximum achievable velocities are less than 1 at the 1.5 x 10^(-11) level. The fact that pions with energies up to 30 TeV are observed to decay into ph…
We discuss astrophysical implications of $κ$-Minkowski space-time, in which there appears space-time noncommutativity. We first derive a velocity formula for particles based on the motion of a wave packet. The result is that a massless particle moves at a constant speed as in the usual Minkowski space-time, which implies that an arrival time analysis by $γ$-rays from Markarian (Mk) 421 does not exclude space-time noncommutativity. Based on this observation, we analyze reaction processes in $κ$-Minkowski space-time which are related to the puzzling detections of extremely high-energy cosmic ray…
Generation of TeV Photons by PeV Neutrinos in Dense Astrophysical Environments
The Hong Kong University of Science and Technology（香港科技大学）；Jockey Club Institute for Advanced Study, The Hong Kong University of Science and Technology（香港科技大学聚龙高等研究院）；School of Physics, Peking University（北京大学物理学院）；Center for Gravitational Wave Experiment, National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences（中国科学院力学研究所微重力国家实验室引力波实验中心）；Department of Physics, Chongqing University（重庆大学物理学院）；School of Physics, Zhengzhou University（郑州大学物理学院）
Cosmic strings can arise in hidden sector models with a spontaneously broken Abelian symmetry group. We have studied the couplings of the Standard Model fields to these so-called dark strings in the companion paper. Here we survey the cosmological and astrophysical observables that could be associated with the presence of dark strings in our universe with an emphasis on low-scale models, perhaps TeV. Specifically, we consider constraints from nucleosynthesis and CMB spectral distortions, and we calculate the predicted fluxes of diffuse gamma ray cascade photons and cosmic rays. For strings as …
Earth absorbs $\nue$ and $\numu$ of energies above about 100 TeV. As is well-known, although $\nutau$ will also disappear through charged-current interactions, the $\nutau$ flux will be regenerated by prompt tau decays. We show that this process also produces relatively large fluxes of secondary $\nube$ and $\nubmu$, greatly enhancing the detectability of the initial $\nutau$. This is particularly important because at these energies $\nutau$ is a significant fraction of the expected astrophysical neutrino flux, and only a tiny portion of the atmospheric neutrino flux.
The assumption of a single astrophysical power-law flux to explain the IceCube 6-year HESE extraterrestrial events yields a large spectral index that is in tension with gamma-ray observations and the 6-year up-going muon neutrinos data. Adopting a spectral index belonging to the range $\left[2.0,2.2\right]$, which is compatible with the one deduced by the analysis performed on the 6-year up-going muon neutrinos data and with $p$-$p$ astrophysical sources, the latest IceCube data show an up to $2.6\,σ$ excess in the number of events in the energy range 40--200 TeV. We interpret such an excess a…
Theories involving extra dimensions, a low (TeV) string scale and bulk singlet neutrinos will produce an effective neutrino magnetic moment which may be large (< 10^{-11} mu_B). The effective magnetic moment increases with neutrino energy, and therefore high energy reactions are most useful for limiting the allowed number of extra dimensions. We examine constraints from both neutrino-electron scattering and also astrophysical environments. We find that supernova energy loss considerations require a number of extra dimensions, n > 1, for an electron neutrino-bulk neutrino Yukawa coupling of ord…
In the framework of brane-world models lowering the Planck scale to the TeV range, it has recently been pointed out that small black holes could be formed at particle colliders or by neutrinos interactions in the atmosphere. This article aims at reviewing other places and epochs where microscopic black holes could be formed : the interstellar medium and the early Universe. The related decay channels and the propagation of the emitted particles are studied to conclude that, in spite of the large creation rate for such black holes, the amount of produced particles do not conflict with experiment…
We study the spectrum, couplings and cosmological and astrophysical implications of the moduli fields for the class of Calabi-Yau IIB string compactifications for which moduli stabilisation leads to an exponentially large volume V ~ 10^{15} l_s^6 and an intermediate string scale m_s ~ 10^{11}GeV, with TeV-scale observable supersymmetry breaking. All Kähler moduli except for the overall volume are heavier than the susy breaking scale, with m ~ ln(M_P/m_{3/2}) m_{3/2} ~ (\ln(M_P/m_{3/2}))^2 m_{susy} ~ 500 TeV and, contrary to standard expectations, have matter couplings suppressed only by the st…
We calculate the atmospheric neutrino fluxes in the energy range $100$ GeV -- $10$ PeV with the use of several known hadronic models and a few parametrizations of the cosmic ray spectra which take into account the knee. The calculations are compared with the atmospheric neutrino measurements by Frejus, AMANDA, IceCube and ANTARES. An analytic description is presented for the conventional ($ν_μ+\barν_μ$) and ($ν_e+\barν_e$) energy spectra, averaged over zenith angles, which can be used to obtain test data of the neutrino event reconstruction in neutrino telescopes. The sum of the calculated atm…
We explore the possibility that high energy astrophysical neutrinos can interact with the dark matter on their way to Earth. Keeping in mind that new physics might leave its signature at such energies, we have considered all possible topologies for effective interactions between neutrino and dark matter. Building models, that give rise to a significant flux suppression of astrophysical neutrinos at Earth, is rather difficult. We present a $Z^{\prime}$-mediated model in this context. Encompassing a large variety of models, a wide range of dark matter masses from $10^{-21}$ eV up to a TeV, this …
Astrophysical gamma-ray sources come in a variety of sizes and magnetizations. We deduce general conditions under which gamma-ray spectra from such sources would be significantly affected by axion-photon mixing. We show that, depending on strength and coherence of the magnetic field, axion couplings down to ~ 1/(10**13 GeV) can give rise to significant axion-photon conversions in the environment of accreting massive black holes. Resonances can occur between the axion mass term and the plasma frequency term as well as between the plasma frequency term and the vacuum Cotton-Mouton shift. Both re…
The IceCube Neutrino Observatory at the South Pole has measured astrophysical neutrinos using through-going and starting events in the TeV to PeV energy range. The origin of these astrophysical neutrinos is still largely unresolved, and among their potential sources could be dark matter decay. Measurements of the astrophysical flux using muon neutrinos are in slight tension with starting event measurements. This tension is driven by an excess observed in the energy range of 40-200 TeV with respect to the through-going expectation. Previous works have considered the possibility that this excess…
We analyze the scenario where the IceCube high energy neutrino events are explained in terms of an extraterrestrial flux due to two different components: a contribution coming from know astrophysical sources for energies up to few hundreds TeV and a top-down contribution originated by the decay of heavy dark matter particles with a mass of few PeV. Contrary to previous approaches, we consider a leptophilic three-body decay that dominates at PeV energies due to the absence of quarks in the final state. We find that the theoretical predictions of such a scenario are in a slightly better agreemen…
We present a novel interpretation of IceCube high energy neutrino events (with energy larger than 60 TeV) in terms of an extraterrestrial flux due to two different contributions: a flux originated by known astrophysical sources and dominating IceCube observations up to few hundreds TeV, and a new flux component where the most energetic neutrinos come from the leptophilic three-body decays of dark matter particles with a mass of few PeV. Differently from other approaches, we provide two examples of elementary particle models that do not require extremely tiny coupling constants. We find the com…
We study scenarios in which there is a hierarchy of two sets of large compactified extra dimensions. One particularly interesting case has a single millimeter size extra dimension and five TeV^{-1} size dimensions. The Standard Model gauge bosons have Kaluza-Klein excitations with respect to one of the TeV scale dimensions. We discuss astrophysical constraints on this scenario, as well as prospects for signals at future high energy colliders.
