Search

Extensive air showers (EAS), produced by cosmic rays in the atmosphere, serve as probes of particle interactions, providing access to energies and kinematical regimes beyond the reach of laboratory experiments. Measurements from multiple cosmic-ray detectors indicate a significant, yet unexplained, discrepancy between the observed muon content in EAS and that predicted by state-of-the-art interaction models, suggesting a need for refinements in our understanding of fundamental physics. Here we show that a tiny, experimentally allowed, violation of the Lorentz invariance (LIV) may result in the suppression of the number of electrons in EAS, leaving the muon number intact and explaining both the ''muon excess'' and its energy dependence. On the other hand, we use the lack of a much stronger discrepancy between EAS data and simulations to obtain strict constraints on the LIV scale. Future experimental tests of this LIV scenario are outlined., Comment: 10 pages, 4 figures. Submitted to Phys. Rev. D

We address the Light-Shining-through thin Wall (LSthinW) laboratory setup to estimate the axion-like particle (ALP) sensitivity of a two radio frequency (RF) cavities immersed in static magnetic field. We show that the sufficiently thin wall between cavities can lead the improved sensitivity of the purely laboratory probes of ALP in the mass range $10^{-6}~\mbox{eV} \lesssim m_a \lesssim 5 \times 10^{-5}~\mbox{eV}$., Comment: 5 pages, 1 figure

We address the radio frequency (RF) cavity experiment for probing dark photons, which is a modification of the light-shining-through-thin-wall (LSthinW) setup with a relatively thin conducting barrier between cylindrical emitter and hollow receiver. The regarding experimental facility allows to probe dark photons effectively even in the off-shell regime, i.~e.~when dark photons mass exceeds the driven frequency of the emitter cavity, that is pumped by electromagnetic mode. We compare the sensitivity of two particular setup configurations: two adjacent cylindrical cavities placed to each other by an end-caps, and the nested geometry of the cavities in which the cylindrical receiver is encapsulated into the emitter. We show that for a certain range of dark photon mass, the nested configuration with $\mbox{TM}_{010}$ pump mode can provide an enhanced sensitivity if one compares that with an adjacent emitter setup. Remarkably, that for $\mbox{TE}_{011}$ pump mode, both nested and adjacent configurations of the cavities can yield comparable expected reaches for the specific geometry type., Comment: 11 pages, 3 figures, 2 tables, major revision

We present shower formation constraints on the Lorentz Invariance Violation (LIV) energy scale for photons with cubic dispersion relation from recent gamma ray observations in $100$ TeV -- PeV energy range by LHAASO observatory. We assume Myers-Pospelov effective field theory framework, and calculate the suppression for the Bethe-Heitler process which is mainly responsible for the formation of photon-initiated atmosphere showers. Comparing the high-energy photon events with the suppressed flux predictions we obtain $95\%$ CL constraints on the LIV energy scale. The obtained shower constraint $E_{\rm LIV} \gtrsim \mathcal{O} \left( 10^{20} \mbox{ GeV}\right)$ is significantly weaker than existing birefringence constraints but is independent., Comment: 11 pages, 1 figure, 1 table; typos corrected, one reference added; results unchanged

We study the process of resonant generation of high-order harmonics in a closed cavity in the model of vacuum nonlinear electrodynamics. Concretely, we study the possibility of resonant generation of the third harmonic induced by a single electromagnetic mode in a radiofrequency cavity, as well as resonant generation of a combined frequency mode induced by two pump modes ($\omega_1$ and $\omega_2$). We explicitly show that the third harmonic as well as the $2\omega_1+\omega_2$ combined frequency mode are not resonantly amplified, while the $2\omega_1-\omega_2$ signal mode is amplified for certain cavity geometry. We discuss the process from the point of view of quantum theory., Comment: 8 pages, 1 figure, 4 tables. Contribution to proceedings of International Conference on Quantum Field Theory, High-Energy Physics, and Cosmology (July 18-21, 2022; JINR, Dubna, Russia), to be published in Phys. Part. Nucl. Lett

The paper studies resonant generation of higher-order harmonics in a closed cavity in Euler-Heisenberg electrodynamics from the point of view of pure quantum field theory. We consider quantum states of the electromagnetic field in a rectangular cavity with conducting boundary conditions, and calculate the cross-section for the merging of three quanta of cavity modes into a single one ($3 \to 1$ process) as well as the scattering of two cavity mode quanta ($2 \to 2$ process). We show that the amplitude of the merging process vanishes for a cavity with an arbitrary aspect ratio, and provide an explanation based on plane wave decomposition for cavity modes. Contrary, the scattering amplitude is nonzero for specific cavity aspect ratio. This $2 \to 2$ scattering is a crucial elementary process for the generation of a quantum of a high-order harmonics with frequency $2\omega_1 - \omega_2$ in an interaction of two coherent states of cavity modes with frequencies $\omega_1$ and $\omega_2$. For this process we calculate the mean number of quanta in the final state in a model with dissipation, which supports the previous result of resonant higher-order harmonics generation in an effective field theory approach., Comment: 11 pages

We discuss the aspects of axion-like-particles (ALPs) searches with Light-Shining-through-Wall (LSW) experimental setups consisted of two radio-frequency cavities. We compare the efficiencies of three setups which involve the cavity pump modes and external magnetic fields. Additionally, we discuss the sensitivity dependence both on the relative position of two cylindrical cavities and on their radius-to-length ratio., Comment: 9 pages, 6 figures, 1 table. Revised version, accepted to JETP Letters

The exploration of the universe has recently entered a new era thanks to the multi-messenger paradigm, characterized by a continuous increase in the quantity and quality of experimental data that is obtained by the detection of the various cosmic messengers (photons, neutrinos, cosmic rays and gravitational waves) from numerous origins. They give us information about their sources in the universe and the properties of the intergalactic medium. Moreover, multi-messenger astronomy opens up the possibility to search for phenomenological signatures of quantum gravity. On the one hand, the most energetic events allow us to test our physical theories at energy regimes which are not directly accessible in accelerators; on the other hand, tiny effects in the propagation of very high energy particles could be amplified by cosmological distances. After decades of merely theoretical investigations, the possibility of obtaining phenomenological indications of Planck-scale effects is a revolutionary step in the quest for a quantum theory of gravity, but it requires cooperation between different communities of physicists (both theoretical and experimental). This review is aimed at promoting this cooperation by giving a state-of-the art account of the interdisciplinary expertise that is needed in the effective search of quantum gravity footprints in the production, propagation and detection of cosmic messengers., Comment: This review was written by participants of the COST Action CA18108. Further information on the review can be found at https://qg-mm.unizar.es/review/, updated to published version

The paper explores a theoretical possibility of resonant amplification of electromagnetic modes generated by a nonlinear effect in Euler-Heisenberg electrodynamics. Precisely, we examine the possibility of the amplification for the third harmonics induced by a single electromagnetic mode in radiofrequency cavity, as well as the generation of signal mode of combined frequencies induced by two pump modes ($\omega_1$ and $\omega_2$) in the cavity. Solving inhomogeneous wave equations for the signal mode, we formulate two resonant conditions for a cavity of arbitrary shape, and apply the obtained formalism to linear and rectangular cavities. We explicitly show that the third harmonics as well as the mode of combined frequency $2\omega_1 + \omega_2$ are not resonantly amplified while the signal mode with frequency $2\omega_1 - \omega_2$ is amplified for a certain cavity geometry., Comment: 10 pages, 5 tables

We present new two-sided constraints on Lorentz Invariance violation energy scale for photons with quartic dispersion relation from recent gamma ray observations by Tibet-AS$\gamma$ and LHAASO experiments. The constraints are based on the consideration of the processes of photon triple splitting (superluminal scenario) and the suppression of shower formation (subluminal). The constraints in subluminal scenario are better than the pair production constraints and are the strongest in the literature., Comment: 11 pages, 2 figures, 1 table. v2: the effect of pair production on CMB has been added

We address production of massive axion-like particles by two electromagnetic modes inside a superconducting radio-frequency (SRF) cylindrical cavity. We discuss in detail the choice of pump modes and cavity design. We numerically compute time-averaged energy density of produced axion field for various cavity modes and wide range of axion masses. This allows us to estimate optimal conditions for axion production within a cavity. In addition, we consider photon regeneration process initiated by produced axion field in a screened radio-frequency cavity and derive constraints in parameter space $(g_{a\gamma\gamma},\ m_a)$ for different choice of pump modes., Comment: 22 pages, 6 figures, 1 table

Recently two collaborations, Tibet and HAWC, presented new measurements of gamma-ray spectrum from Crab Nebula \cite{Amenomori:2019rjd},\cite{Abeysekara:2019edl} which continues beyond $100$ TeV. We use these data to establish two-sided constraints on parameters of Lorentz Invariance violation in quantum electrodynamics. The limits on Lorentz violating mass scale for quartic dispersion relation are $4.1\times 10^{14}\ \mbox{GeV}$ (photon splitting) and $1.9\times 10^{13}\ \mbox{GeV}$ (photon decay) for superluminal case, and $1.4\times 10^{12}$ GeV (suppression of shower formation) for subluminal case., Comment: 9 pages

We calculate the decay width of the photon splitting into three photons in a model of quantum electrodynamics with broken Lorentz invariance. We show that this process can lead to a cut-off in the very-high-energy part of a photon spectra of astrophysical sources. We obtain the 95\% CL bound on the Lorentz violating mass scale for photons from the analysis of the very-high-energy part of the Crab Nebula spectrum, obtained by HEGRA. This bound improves previous constraints by more than an order of magnitude., Comment: 15 pages, 2 figures

We calculate a finite momentum-dependent part of the photon polarization operator in a simple model of Lorentz-violating quantum electrodynamics nonperturbatively at all orders of Lorentz-violating parameters. We sum one-particle reducible diagrams into the modified photon propagator, and determine the physical photon dispersion relation as the location of its pole. The photon dispersion relation, as well as its group velocity, acquires the one-loop momentum-dependent radiative correction. We constrain the Lorentz-violating parameters for heavy charged fermions (muon, $\tau$-lepton, top-quark) from the photon timing observations., Comment: 14 pages, revisited version

We discuss the effect of hypothetical violation of Lorentz invariance at high energies on the formation of atmospheric showers by very-high-energy gamma rays. In the scenario where Lorentz invariance violation leads to a decrease of the photon velocity with energy the formation of the showers is suppressed compared to the Lorentz invariant case. Absence of such suppression in the high-energy part of spectrum of the Crab nebula measured independently by HEGRA and H.E.S.S. collaborations is used to set lower bounds on the energy scale of Lorentz invariance violation. These bounds are competitive with the strongest existing constraints obtained from timing of variable astrophysical sources and the absorption of TeV photons on the extragalactic background light. They will be further improved by the next generation of multi-TeV gamma-ray observatories., Comment: 21 pages, 4 figures. References added

We study the process of neutrino decay to electron and $W$-boson in the external magnetic field using the semiclassical "worldline instanton" approach. Being interested only in the leading exponential factor, we make calculations in a toy model, treating all particles as scalars. This calculation determines the effective threshold energy of the reaction as a function of the magnetic field. Possible astrophysical applications are discussed. It is emphasized that the method is general and is applicable to a decay of an arbitrary neutral particle into charged ones in the external electromagnetic field., Comment: 13 pages, 2 figures

We point out that violation of Lorentz invariance affects the interaction of high-energy photons with the Earth's atmosphere and magnetic field. In certain parameter region this interaction becomes suppressed and the photons escape observation passing through the atmosphere without producing air showers. We argue that a detection of photon-induced air showers with energies above 10^19 eV, implying the absence of suppression as well as the absence of photon decay, will put tight double-sided limits on Lorentz violation in the sector of quantum electrodynamics. These constraints will be by several orders of magnitude stronger than the existing ones and will be robust against any assumptions about the astrophysical origin of the detected photons., Comment: 6 pages, revtex; significant additions compared to the previous version

We show that violation of the Lorentz symmetry in quantum electrodynamics can suppress the rates of the interactions crucial for the formation of photon-induced air showers, such as pair production on nuclei and in the geomagnetic field. As a consequence, the allowed region in the space of Lorentz-violating parameters will be seriously restricted if several photons with energies $\gtrsim\,10^{19}\, {eV}$ are detected., Comment: Presented at the Sixth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, June 17-21, 2013

We present an elementary derivation of the width of photon decay in a weak magnetic field using the semiclassical method of worldline instantons. The calculation is generalized to a model of quantum electrodynamics with broken Lorentz symmetry. Implications for the search of deviations from Lorentz invariance in the cosmic ray experiments are discussed., Comment: 12 pages, 1 figure

We develop a systematic approach to the calculation of scattering cross sections in theories with violation of the Lorentz invariance taking into account the whole information about the theory Lagrangian. As an illustration we derive the Feynman rules and formulas for sums over polarizations in spinor electrodynamics with Lorentz violating operators of dimensions four and six. These rules are applied to compute the probabilities of several astrophysically relevant processes. We calculate the rates of photon decay and vacuum Cherenkov radiation along with the cross sections of electron-positron pair production on background radiation and in the Coulomb field. The latter process is essential for detection of photon-induced air showers in the atmosphere., Comment: 23 pages, 1 figure