Search

We discuss the transverse single spin asymmetries $A_N$ for very forward neutrons measured by the PHENIX zero-degree calorimeters (ZDCs) in high-energy polarized proton-nucleus ($p$-A) collisions at Relativistic Heavy Ion Collider (RHIC). The ZDCs cover the psudorapidity range of $6.8

Axion as one of the promising dark matter candidates can be detected through narrow radio lines emitted from the magnetic white dwarf stars. Due to the existence of the strong magnetic field, the axion may resonantly convert into the radio photon (Primakoff effect) when it passes through a narrow region in the corona of the magnetic white dwarf, where the plasma frequency is equal to the axion mass. We show that for the magnetic white dwarf WD 2010+310, the future experiment SKA phase 1 with 100 hours of observation can effectively probe the parameter space of the axion-photon coupling gaγ up to ∼10−12 GeV−1 for the axion mass range of 0.2∼3.7 μeV. Note that in the low mass region (ma≲1.5 μeV), the WD 2010+310 could give greater sensitivity than the neutron star RX J0806.4-4123.

The aim of the proposed CERN Gamma Factory is to produce $\sim 10^{17}$ photons per second with energies up to 400 MeV. The photon beam intensity is expected to be a factor of $\mathcal{O}(10^7)$ larger than that of the presently available photon beams in the MeV energy range. In this work, we explore its potential to probe physics beyond the Standard Model. In particular, we discuss searches for axion like particles (ALPs) with dominant couplings to photons and consider various production scenarios - fixed target, photon-photon collision, and conversion by a magnetic field and detection schemes - via decay to photons or back-conversion. We find that the Gamma Factory in a fixed target mode can probe ALPs with mass $m_a \lesssim \mathcal{O}(100\,\mathrm{MeV})$ and decay constants larger than $10^7$ GeV, improving by an order of magnitude the discovery potential of previous beam dump experiments., 12 pages, 4 figures

We study a Lorentz invariance violating extension for the pure photonic sector of the standard model in a supersymmetric scenario. We identify a number of independent background fermion condensates. An effective photonic action is proposed which is induced by the SUSY background fermion condensates. The physical consequences leading to direct measurable effects over the screening and confining properties are considered. In the specific case of the Carroll-Field-Jackiw, we pay special attention in analyzing the dispersion relations to derive the photon and photino masses in terms of the supersymmetric background parameters. In connection with astrophysical aspects of Lorentz-symmetry violation, we discuss the time delay between electromagnetic waves of different frequencies as a consequence of the appearance of the massive photon. We also point out that, in the scenario we propose to accommodate Lorentz-symmetry violation in presence of a supersymmetric background, there is room for a sort of fermionic Primakoff effect in which a photino-photon conversion may be induced by the fermionic sector of the supersymmetric background., Comment: 25 pages. This work has been submitted for publication in the Special Issue, "Lorentz Violation in Astroparticles and Gravitational Waves", of Galaxies

A real-time Data Acquisition (DAQ) system for the CULTASK axion haloscope experiment was constructed and tested. The CULTASK is an experiment to search for cosmic axions using resonant cavities, to detect photons from axion conversion through the inverse Primakoff effect in a few GHz frequency range in a very high magnetic field and at an ultra low temperature. The constructed DAQ system utilizes a Field Programmable Gate Array (FPGA) for data processing and Fast Fourier Transformation. This design along with a custom Ethernet packet designed for real-time data transfer enables 100% DAQ efficiency, which is the key feature compared with a commercial spectrum analyzer. This DAQ system is optimally designed for RF signal detection in the axion experiment, with 100 Hz frequency resolution and 500 kHz analysis window. The noise level of the DAQ system averaged over 100,000 measurements is around -111.7 dBm. From a pseudo-data analysis, an improvement of the signal-to-noise ratio due to repeating and averaging the measurements using this real-time DAQ system was confirmed.

We investigate photoproduction of axial vector meson ${f}_{1}(1285)$ based on the CLAS experiment $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{f}_{1}(1285)\ensuremath{\rightarrow}p\ensuremath{\eta}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ using the Regge model for ${\ensuremath{\rho}}^{0}+\ensuremath{\omega}$ exchanges. The combined analysis of $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\eta}}^{\ensuremath{'}}\ensuremath{\rightarrow}p\ensuremath{\eta}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ reaction including $\ensuremath{\eta}(1295)$ is accompanied to evaluate the decay mode $\ensuremath{\eta}(1295)\ensuremath{\rightarrow}\ensuremath{\eta}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ from the potential overlap with the ${f}_{1}$ reaction. The predominance of ${\ensuremath{\rho}}^{0}(770)$ exchange over the $\ensuremath{\omega}(782)$ with the coupling constant $\ensuremath{\gamma}{\ensuremath{\rho}}^{0}{f}_{1}$ extracted from the CLAS experiment leads to a good description of the measured cross sections for ${f}_{1}$, while the scale of the cross section is corrected by the branching fraction ${\ensuremath{\eta}}^{\ensuremath{'}}\ensuremath{\rightarrow}\ensuremath{\eta}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and ${f}_{1}\ensuremath{\rightarrow}\ensuremath{\eta}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, respectively. As an extension to study the nonmesonic production mechanism, the Primakoff effect by the virtual photon exchange is investigated in the exclusive reaction $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{f}_{1}$ up to $\sqrt{s}\ensuremath{\approx}50\text{ }\text{ }\mathrm{GeV}$, playing role similar to the Pomeron in the vector meson photoproduction at high energies. Such a unique role of the virtual photon exchange similar to the ${f}_{1}$ case is identified up to $\sqrt{s}\ensuremath{\approx}250\text{ }\text{ }\mathrm{GeV}$ in the $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{0}$ and $\ensuremath{\gamma}p\ensuremath{\rightarrow}p\ensuremath{\eta}$ as well as $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\eta}}^{\ensuremath{'}}$ reactions.

We study the evolution of axions interacting with primordial magnetic fields (PMFs) starting just from the QCD phase transition in the expanding universe. This interaction is owing to the Primakoff effect. Adopting the zero mode approximation for axions, we derive the system of equations for axions and magnetic fields, where the expansion of the universe and the spectra of magnetic fields are accounted for exactly. We find that the contribution of the Primakoff effect to the dynamics of axions and magnetic fields is rather weak. It confirms some previous estimates leading to analogous conclusions, when accounting here for the Hubble expansion both for an uniform axion field and non-uniform PMFs using Fourier spectra for their energy and helicity densities. We solve the corresponding system of the evolution equations and find that the axion zero mode, when evolving during radiation era, has its amplitude at the level sufficient for that axion to be a good candidate for the cold dark matter., Comment: 8 pages in Revtex, 4 eps figures; accepted for publication in Phys.Rev.D

We propose a novel method to search for axion-like particles (ALPs) at particle accelerator experiments (exps). ALPs produced at the target via the Primakoff effect subsequently enter a region with a magnetic field, where they are converted to photons that are then detected. Dubbed Particle Accelerator helioScopes for Slim Axion-like-particle deTection (PASSAT), our proposal uses the principle of the axion helioscope but replaces ALPs produced in Sun with those produced in a target material. Since we rely on ALP-photon conversions, our proposal probes light (slim) ALPs that are otherwise inaccessible to lab-based exps which rely on ALP decay, and complements astrophysical probes that are more model-dependent. We first reinterpret existing data from the NOMAD exp in light of PASSAT, and constrain the parameter space for ALPs lighter than ~100 eV and ALP-photon coupling larger than ~$10^{-4}$ GeV$^{-1}$. As benchmarks of feasible low-cost exps improving over the NOMAD limits, we study the possibility of reusing the magnets of the CAST and the proposed BabyIAXO exps and placing them at the proposed BDF facility at CERN, along with some new detectors. We find that these realizations of PASSAT allow for a direct probe of the parameter space for ALPs lighter than ~100 eV and ALP-photon coupling larger than ~4 x $10^{-6}$ GeV$^{-1}$, which are regions that have not been probed yet by exps with lab-produced ALPs. In contrast to other proposals aiming at detecting 1 or 2-photon only events in hadronic beam dump environments, that rely heavily on Monte Carlo simulations, the background (BG) in our proposal can be directly measured in-situ, its suppression optimized, and the irreducible BG statistically subtracted. Sensitivity studies with other beams will be the subject of future work. The measurements suggested here represent an additional physics case for the BDF beyond those already proposed., 8 pages, 3 figures, 1 table, Journal-submitted version

The Axion Like Particle (ALP) is a hypothetical pseudo-scalar particle beyond the Standard Model, with a compelling possible connection to dark matter and early universe physics. ALPs can be converted into photons via interactions with magnetic fields in the universe, i.e., the so-called inverse Primakoff effect. In this paper, we propose a novel method to explore ALP-induced photons from X-ray data obtained from the {\it Suzaku} satellite, arising from a possible interaction of ALPs with the direction-dependent Earth's magnetic field viewed from the satellite. {\it Suzaku} data is suitable for this purpose because its low-altitude Earth orbit result in intrinsically low cosmic-ray background radiation. We study whether the X-ray diffuse background (XDB) spectra estimated from the four deep fields collected over eight years, vary with the integrated Earth's magnetic strength in the direction of each target field at each observation epoch, which amounts to $10^2$ Tm-a value greater than that achieved by terrestrial experiments due to the large coherent length. From the detailed analysis, we did not find evidence of the XDB confidence level spectra having dependence on the Earth's magnetic strength. We obtained 99 % confidence level upper limit on a possible residual contribution to the cosmic X-ray background (CXB) surface brightness to be $1.6\times 10^{-9}~{\rm ergs~s}^{-1}{\rm cm}^{-2}{\rm sr}^{-1}$ normalized at $10^4$ T${}^2$ m${}^2$ in the 2-6 keV range, which corresponds to 6-15 % of the observed CXB brightness, depending on which model of unresolved point sources are used in the interpretation. It is consistent with 80-90 % of the CXB now being resolved into point sources., Comment: 13 pages, 4 figures, Prepared for submission to JCAP

Axions or more generally axion-like particles (ALPs) are pseudo-scalar particles predicted by many extensions of the Standard Model of particle physics (SM) and considered as viable candidates for dark matter (DM) in the universe. If they really exist in nature, they are expected to couple with photons in the presence of an external electromagnetic field through a form of the Primakoff effect. In addition, many string theory models of the early universe motivate the existence of a homogeneous Cosmic ALP Background (CAB) with 0.1-1 keV energies analogous to the Cosmic Microwave Background (CMB), arising via the decay of string theory moduli in the very early universe. The coupling between the CAB ALPs traveling in cosmic magnetic fields and photons allows ALPs to oscillate into photons and vice versa. In this work, we test the CAB model that is put forward to explain the soft X-ray excess in the Coma cluster due to CAB ALPs conversion into photons using the M87 jet environment. Then we demonstrate the potential of the active galactic nuclei (AGNs) jet environment to probe low-mass ALP models, and to potentially constrain the model proposed to better explain the Coma cluster soft X-ray excess. We find that the overall X-ray emission for the M87 AGN requires an ALP-photon coupling $g_{a\gamma}$ in the range of $\sim7.50\times 10^{-15}-6.56\times 10^{-14}$ GeV$^{-1}$ for ALP masses $m_a \lesssim 10^{-13}$ eV as long as the M87 jet is misaligned by less than about 20 degrees from the line of sight. These values are up to an order of magnitude smaller than the current best fit value on $g_{a\gamma}\sim 2\times 10^{-13}$ GeV$^{-1}$ obtained in soft X-ray excess CAB model for the Coma cluster. Our results cast doubt on the current limits of the largest allowed value of $g_{a\gamma}$ and suggest a new constraint that $g_{a\gamma}\lesssim 6.56\times 10^{-14}$ GeV$^{-1}$ when a CAB is assumed., Comment: This work is prepared for submission to JCAP

Due to the inverse Primakoff effect it has been shown that when axions interact with a DC magnetic B-field the resulting electrical action will produce an AC electromotive force which oscillates at the Compton frequency of the axion, and may be modeled as an oscillating effective impressed magnetic current boundary source. We use this result to calculate the sensitivity of new experiments to low-mass axions using the quasi-static technique. First, we calculate the current induced in an electric dipole antenna (straight conducting wire) when the DC B-field is spatially constant and show that it has a sensitivity proportional to the axion mass. Following this we extend the topology by making use of the full extent of the spatially varying DC B-field. This extension is achieved by transforming the 1D conducting wire to a 2D winding, to fully link the effective magnetic current boundary source and thus couple to the full axion induced electrical action. In this case the conductor becomes a coil winding where the voltage induced across the winding increases proportionally to the number of windings. We investigate two different topologies: The 1st uses a single winding, and couples to the effective short circuit current generated in the winding, which is read out using a sensitive low impedance SQUID amplifier: The 2nd uses multiple windings, with every turn effectively increasing the the voltage output proportional to the winding number. The read out of this configuration is optimised by implementing a cryogenic low-noise high input impedance voltage amplifier. The end result is a new Broadband Electrical Action Sensing Techniques with orders of magnitude improved sensitivity, which is linearly proportional to the axion photon coupling and capable of detecting QCD dark matter axions., Final accepted journal version. Two misconceptions fixed as required by referee compared to last version. Additions are in color, red for one point of misconception and blue for the other point

Baby-IAXO is a new helioscope, a demonstration version of the proposed full-size IAXO, the International Axions Observatory. It is currently under design and once installed it will search via the Primakoff effect for axions or axion-like particles (ALPs) originating in the Sun. Axions can transform into photons in the presence of a significant magnetic field, and then be detected. The superconducting magnet for Baby-IAXO comprises two 10 m long racetrack coils, spaced by 0.8 m, operated in a quadrupole configuration and generating an average magnetic field of 2.1 T in the two 700 mm diameter free bores for axion-to-photons decay positioned in between the coils. Cool down and operational cryogenic requirements are handled by a combination of single and double stage cryocoolers. For the cool down of the 18.5 t cold mass within 22 days and for current leads cooling, the use of powerful single stage cryocoolers is of paramount importance. The cooling power is distributed across the cold mass and thermal shield using helium gas flow enforced by cryocirculators. The design of the 10 kA conduction cooled current leads is presented as well, since at 70 K these represent the dominant heat load. The cryogenic system allows for a constant heat load of 1.2 kW at the first stage and 8.5 W at the 4.2 K cold mass. Alternatively, the magnet may be operated in persistent mode, thereby reducing the heat load and the number of cryocoolers. It requires a more complex cooling circuit, implementation of a 10 kA persistent mode switch, and a delicate balance of energizing and operational heat loads.

International audience; More than 80 years after the postulation of dark matter, its nature remains one of the fundamental questions in cosmology. Axions are currently one of the leading candidates for the hypothetical, non-baryonic dark matter that is expected to account for about 25% of the energy density of the Universe. Especially in the light of the Large Hadron Collider at CERN slowly closing in on Weakly-Interacting Massive Particle (WIMP) searches, axions and axion-like particles (ALPs) provide a viable alternative approach to solving the dark matter problem. The fact that makes them particularly appealing is that they were initially introduced to solve a long-standing problem in quantum chromodynamics and the Standard Model of particle physics.Helioscopes are a type of axion experiment searching for axions produced in the core of the Sun via the Primakoff effect. The International Axion Observatory (IAXO) is a next generation axion helioscope aiming at a sensitivity to the axion-photon coupling of 1 − 1.5 orders of magnitude beyond the current most sensitive axion helioscope, which is the CERN Axion Solar Telescope (CAST). IAXO will be able to challenge the stringent bounds from supernova SN1987A and test the axion interpretation of anomalous white-dwarf cooling. Beyond standard axions, this new experiment will also be able to search for a large variety of axion-like particles and other novel excitations at the low-energy frontier of elementary particle physics. BabyIAXO is proposed as an intermediate-scale experiment increasing the sensitivity to axion-photon couplings down to a few 10$^{−11}$ GeV$^{−1}$ and thus delivering significant physics results while demonstrating the feasibility of the full-scale IAXO experiment. Here we introduce the IAXO and BabyIAXO experiments, report on the current status of both and outline the expected IAXO science reach.

We advocate the idea that there is a fundamentally new mechanism for the axion production in the Sun, which has never been discussed previously in the literature. This novel mechanism of the axion production is based on the so-called Axion Quark Nugget (AQN) Dark Matter Model. These axions will be produced in addition to well studied axions emitted due to the Primakoff effect. The AQN model was originally invented as a natural explanation of the observed ratio $\Omega_{\rm dark} \sim \Omega_{\rm visible}$ when the DM and visible matter densities assume the same order of magnitude values, irrespectively to the axion mass $m_a$ or initial misalignment angle $\theta_0$. This model, without adjustment of any parameters, reproduces reasonably the intensity of the extreme UV (EUV) radiation from the solar corona as a result of the AQN annihilation events with the solar material. This extra energy released in corona represents a resolution, within AQN framework, a long standing puzzle known in the literature as the "solar corona heating mystery". The same annihilation events also produce the relativistic axions. This represents a new mechanism of the axion production, and constitutes the main subject of this work. The flux of these axions is unambiguously fixed in this model and expressed in terms of the EUV luminosity from corona. We also compute the spectral properties of these axions and make few comments on the potentials for the discovery of these solar axions by the upgraded CAST (CERN Axion Solar Axion) experiment., Comment: matches the published version

Electron Compton scattering is the best known fundamental QED process, however, a precision measurement of its cross section for a beam energy above 1 GeV has been lacking up to now. An updated high precision measurement of the neutral pion lifetime via the Primakoff effect (PrimEx-II) experiment was performed in Hall B of Jefferson Lab in 2010. The experiment used small angle coherent photoproduction of π 0’s in the Coulomb field of a nucleus, i:e: the Primakoff effect, to determine the lifetime with a precision of less than 1:5% . It therefore requires thorough understanding of the underlying systematic uncertainties. To facilitate that data for well known electromagnetic processes were taken concurrently with the photoproduction data. This analysis pertains to measuring the Compton scattering cross section, which occurs with similar kinematics to the primary process. The combination of the well established theory for this process with large collected statistics allowed to extract this cross section with high precision in an energy region of 4-5 GeV for 12C and 28Si targets. The results of this analysis will be presented.

Axion haloscope detectors use microwave cavities permeated by a magnetic field to resonate photons that are converted from axions due to the inverse Primakoff effect. The sensitivity of a detector is proportional to the form factor of the cavity’s search mode. Transverse symmetry breaking is used to tune the search modes for scanning across a range of axion masses. However, numerical analysis shows transverse and longitudinal symmetry breaking reduce the sensitivity of the search mode. Simulations also show longitudinal symmetry breaking leads to other undesired consequences like mode mixing and mode crowding. The results complicate axion dark matter searches and further reduce the search capabilities of detectors. The findings of a numerical analysis of symmetry breaking in haloscope microwave cavities are presented.

The CERN Axion Solar Telescope (CAST) is a helioscope looking for axions arising from the solar core plasma and arriving to Earth. The experiment, located in Geneva (Switzerland) is able to follow the Sun during sunrise and sunset. Four x-ray detectors mounted on both ends of the magnet wait for photons from axion-to-photon conversion due to the Primakoff effect. Up to date, with the completion of Phases I and II, CAST has been looking for axions that could be produced in the Sun by both, hadronic and non-hadronic mechanisms.

Highly magnetized neutron stars known as magnetars are some of the most interesting objects in the Universe. Non-baryonic dark matter candidate axions are produced in the highly magnetized neutron star via Bremsstrahlung process in the highly dense medium. These axions thus produced are then converted into photons in the strong magnetic field via Primakoff effect giving rise to the observed X-ray luminosity level of these objects. Our results are found within observational limit of SGRs(1806-20, 1900 $$+$$ 14,0526-66 and 1627-41) and AXPs(4U0142 $$+$$ 61,1E1048-5937,RXS1708-4009 and 1E1841-045).

We review the achievements of the project B.5 , that deals with the calculation of in-medium properties of vector mesons and an analysis of their experimental signals, with a particular emphasis on the ω photoproduction data from CBELSA/TAPS. Other topics addressed include color transparency, pion electroproduction on nucleons, the Primakoff effect for nuclear targets and studies of hadronization at the EIC.

The coherent Bragg scattering of photons converted from solar axions inside crystals would boost the signal for axion-photon coupling enhancing experimental sensitivity for these hypothetical particles. Knowledge of the scattering angle of solar axions with respect to the crystal lattice is required to make theoretical predications of signal strength. Hence, both the lattice axis angle within a crystal and the absolute angle between the crystal and the Sun must be known. In this paper, we examine how the experimental sensitivity changes with respect to various experimental parameters. We also demonstrate that, in a multiple-crystal setup, knowledge of the relative axis orientation between multiple crystals can improve the experimental sensitivity, or equivalently, relax the precision on the absolute solar angle measurement. However, if absolute angles of all crystal axes are measured, we find that a precision of 2-4 degrees will suffice for an energy resolution of $\sigma_E=0.04{\rm E}$ and a flat background. Finally, we also show that, given a minimum number of detectors, a signal model averaged over angles can substitute for precise crystal angular measurements, with some loss of sensitivity., Comment: 16 pages, 12 figures. Published version with improvements suggested by referee