arXiv subjects

J. Jaeckel

Publications and source records attributed to J. Jaeckel.

At least 19 recordsLinked to original sources

arXiv2026

Testing New Scalar Interactions in Few-Electron Highly Charged Ions

We investigate how a hypothetical scalar boson mediating an interaction between electrons as well as between electrons and nucleons would affect the g factor of lithium-like highly charged ions. In such ions, the strong nuclear Coulomb fields enhance electron-electron interactions, making them ideal systems for detecting subtle new physics signatures. Exceptionally accurate quantum electrodynamic predictions and experimental data in such few-electron systems allow for sensitive probes, thereby enabling bounds on the boson's coupling strength. Exploiting the enhanced sensitivity of highly charged ions to short-range interactions, we combine g-factor measurements and quantum electrodynamic theory predictions of lithium- and hydrogen-like ions with the free-electron magnetic moment and an isotope-shift measurement to constrain simultaneously the electron-proton, electron-neutron, and electron-electron coupling combinations as functions of the scalar mass. We find that precision g-factor spectroscopy provides competitive constraints on scalar interactions over a broad mass range and, in particular, yields bounds on electron-electron interactions from bound-state QED observables.

hep-ph↗

arXiv2025

Summary Report of the Physics Beyond Colliders Study at CERN

The Physics Beyond Collider (PBC) Study Group was initially mandated by the CERN Management to prepare the previous European Particle Physics Strategy Update for CERN projects other than the high-energy frontier colliders. The main findings were summarized in an PBC Summary Report submitted to the Strategy Update. Following the Update process, the PBC Study Group was confirmed on a permanent basis with an updated mandate taking into account the strategy recommendations. The Study Group is now in charge of supporting the proponents of new ideas to address the technical issues and physics motivation of the projects ahead of their review by the CERN Scientific Committees and decision by the Management. The present document updates the previous PBC summary report to inform the new ongoing European Particle Physics Strategy Update process, taking into account the evolution of the CERN and worldwide landscapes and the new projects under consideration within the Study Group.

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arXiv2025

Limits on New Lorentz-violating Bosons

We obtain novel constraints on new scalar fields interacting with Standard Model fermions through Lorentz-violating couplings, bridging searches for scalar particles and Lorentz-symmetry tests. These constraints arise from torsion-balance experiments, magnetometer searches, and an excessive energy loss in Red Giant stars. Torsion-balance experiments impose stringent constraints, benefitting from large macroscopic sources including the Sun and Earth. Magnetometer-based searches, which detect pseudo-magnetic fields through spin precession, offer additional limiting power to low-mass scalar fields. Meanwhile, observations of Red Giant stars place strong limits on additional energy loss mechanisms, extending these constraints to higher scalar mass ranges and a wider range of Lorentz-violating couplings. Combining data from laboratory experiments and astrophysical observations, this approach strengthens constraints on Lorentz-violating interactions and paves the way for future investigations into physics beyond the Standard Model.

hep-ph↗

arXiv2023

Post-LS3 Experimental Options in ECN3

The Experimental Cavern North 3 (ECN3) is an underground experimental cavern on the CERN Pr\'evessin site. ECN3 currently hosts the NA62 experiment, with a physics programme devoted to rare kaon decays and searches of hidden particles approved until Long Shutdown 3 (LS3). Several options are proposed on the longer term in order to make best use of the worldwide unique potential of the high-intensity/high-energy proton beam extracted from the Super Proton Synchrotron (SPS) in ECN3. The current status of their study by the CERN Physics Beyond Colliders (PBC) Study Group is presented, including considerations on beam requirements and upgrades, detector R&D and construction, schedules and cost, as well as physics potential within the CERN and worldwide landscape.

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arXiv2022

New Horizons: Scalar and Vector Ultralight Dark Matter

The last decade has seen unprecedented effort in dark matter model building at all mass scales coupled with the design of numerous new detection strategies. Transformative advances in quantum technologies have led to a plethora of new high-precision quantum sensors and dark matter detection strategies for ultralight ($<10\,$eV) bosonic dark matter that can be described by an oscillating classical, largely coherent field. This white paper focuses on searches for wavelike scalar and vector dark matter candidates.

hep-ex↗

arXiv2022

Axion Dark Matter

Axions are well-motivated dark matter candidates with simple cosmological production mechanisms. They were originally introduced to solve the strong CP problem, but also arise in a wide range of extensions to the Standard Model. This Snowmass white paper summarizes axion phenomenology and outlines next-generation laboratory experiments proposed to detect axion dark matter. There are vibrant synergies with astrophysical searches and advances in instrumentation including quantum-enabled readout, high-Q resonators and cavities and large high-field magnets. This white paper outlines a clear roadmap to discovery, and shows that the US is well-positioned to be at the forefront of the search for axion dark matter in the coming decade.

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arXiv2020

Limits from the Funk Experiment on the Mixing Strength of Hidden-Photon Dark Matter in the Visible and Near-Ultraviolet Wavelength Range

We present results from the FUNK experiment in the search for hidden-photon dark matter. Near the surface of a mirror, hidden photons may be converted into ordinary photons. These photons are emitted perpendicular to the surface and have an energy equal to the mass of the dark matter hidden photon. Our experimental setup consists of a large, spherical mirror with an area of more than 14 m$^2$, which concentrates the emitted photons into its central point. Using a detector sensitive to visible and near-UV photons, we can exclude a kinetic-mixing coupling of stronger than $χ\approx 10^{-12}$ in the mass range of 2.5 to 7 eV, assuming hidden photons comprise all of the dark matter. The experimental setup and analysis used to obtain this limit are discussed in detail.

astro-ph.CO↗

arXiv2019

Physics Beyond Colliders at CERN: Beyond the Standard Model Working Group Report

The Physics Beyond Colliders initiative is an exploratory study aimed at exploiting the full scientific potential of the CERN's accelerator complex and scientific infrastructures through projects complementary to the LHC and other possible future colliders. These projects will target fundamental physics questions in modern particle physics. This document presents the status of the proposals presented in the framework of the Beyond the Standard Model physics working group, and explore their physics reach and the impact that CERN could have in the next 10-20 years on the international landscape.

hep-ex↗

arXiv2019

Summary Report of Physics Beyond Colliders at CERN

Physics Beyond Colliders is an exploratory study aimed at exploiting the full scientific potential of CERN's accelerator complex and its scientific infrastructure in the next two decades through projects complementary to the LHC, HL-LHC and other possible future colliders. These projects should target fundamental physics questions that are similar in spirit to those addressed by high-energy colliders, but that require different types of beams and experiments. A kick-off workshop held in September 2016 identified a number of areas of interest and working groups have been set-up to study and develop these directions. All projects currently under consideration are presented including physics motivation, a brief outline of the experimental set-up and the status of the corresponding beam and detector technological studies. The proposals are also put in context of the worldwide landscape and their implementation issues are discussed.

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arXiv2018

Decay photons from the ALP burst of type-II supernovae

We determine limits from SN 1987A on massive axion-like particles (ALPs) with masses in the 10 keV - 100 MeV range and purely coupled to two photons. ALPs produced in the core collapse escape from the star and decay into photons that can be observed as a delayed and diffuse burst. We discuss the time and angular distribution of such a signal. Looking into the future we also estimate the possible improvements if the red supergiant Betelgeuse explodes in a supernova event.

hep-ph↗

arXiv2018

Attractive vs. repulsive interactions in the Bose-Einstein condensation dynamics of relativistic field theories

We study the impact of attractive self-interactions on the nonequilibrium dynamics of relativistic quantum fields with large occupancies at low momenta. Our primary focus is on Bose-Einstein condensation and nonthermal fixed points in such systems. As a model system we consider O(N)-symmetric scalar field theories. We use classical-statistical real-time simulations, as well as a systematic 1/N expansion of the quantum (2PI) effective action to next-to-leading order. When the mean self-interactions are repulsive, condensation occurs as a consequence of a universal inverse particle cascade to the zero-momentum mode with self-similar scaling behavior. For attractive mean self-interactions the inverse cascade is absent and the particle annihilation rate is enhanced compared to the repulsive case, which counteracts the formation of coherent field configurations. For N >= 2, the presence of a nonvanishing conserved charge can suppress number changing processes and lead to the formation of stable localized charge clumps, i.e. Q-balls.

hep-ph↗

arXiv2017

Search for hidden-photon dark matter with the FUNK experiment

Many extensions of the Standard Model of particle physics predict a parallel sector of a new U(1) symmetry, giving rise to hidden photons. These hidden photons are candidate particles for cold dark matter. They are expected to kinetically mix with regular photons, which leads to a tiny oscillating electric-field component accompanying dark matter particles. A conducting surface can convert such dark matter particles into photons which are emitted almost perpendicularly to the surface. The corresponding photon frequency follows from the mass of the hidden photons. In this contribution we present a preliminary result on a hidden photon search in the visible and near-UV wavelength range that was done with a large, 14 m2 spherical metallic mirror and discuss future dark matter searches in the eV and sub-eV range by application of different detectors for electromagnetic radiation.

hep-ex↗

arXiv2017

Search for hidden-photon Dark Matter with FUNK

It has been proposed that an additional U(1) sector of hidden photons could account for the Dark Matter observed in the Universe. When passing through an interface of materials with different dielectric properties, hidden photons can give rise to photons whose wavelengths are related to the mass of the hidden photons. In this contribution we report on measurements covering the visible and near-UV spectrum that were done with a large, 14 m2 spherical metallic mirror and discuss future dark-matter searches in the eV and sub-eV range by application of different electromagnetic radiation detectors.

hep-ex↗

arXiv2014

Conceptual Design of the International Axion Observatory (IAXO)

The International Axion Observatory (IAXO) will be a forth generation axion helioscope. As its primary physics goal, IAXO will look for axions or axion-like particles (ALPs) originating in the Sun via the Primakoff conversion of the solar plasma photons. In terms of signal-to-noise ratio, IAXO will be about 4-5 orders of magnitude more sensitive than CAST, currently the most powerful axion helioscope, reaching sensitivity to axion-photon couplings down to a few $\times 10^{-12}$ GeV$^{-1}$ and thus probing a large fraction of the currently unexplored axion and ALP parameter space. IAXO will also be sensitive to solar axions produced by mechanisms mediated by the axion-electron coupling $g_{ae}$ with sensitivity $-$for the first time$-$ to values of $g_{ae}$ not previously excluded by astrophysics. With several other possible physics cases, IAXO has the potential to serve as a multi-purpose facility for generic axion and ALP research in the next decade. In this paper we present the conceptual design of IAXO, which follows the layout of an enhanced axion helioscope, based on a purpose-built 20m-long 8-coils toroidal superconducting magnet. All the eight 60cm-diameter magnet bores are equipped with focusing x-ray optics, able to focus the signal photons into $\sim 0.2$ cm$^2$ spots that are imaged by ultra-low-background Micromegas x-ray detectors. The magnet is built into a structure with elevation and azimuth drives that will allow for solar tracking for $\sim$12 h each day.

physics.ins-det↗

arXiv2013

Dark Sectors and New, Light, Weakly-Coupled Particles

Dark sectors, consisting of new, light, weakly-coupled particles that do not interact with the known strong, weak, or electromagnetic forces, are a particularly compelling possibility for new physics. Nature may contain numerous dark sectors, each with their own beautiful structure, distinct particles, and forces. This review summarizes the physics motivation for dark sectors and the exciting opportunities for experimental exploration. It is the summary of the Intensity Frontier subgroup "New, Light, Weakly-coupled Particles" of the Community Summer Study 2013 (Snowmass). We discuss axions, which solve the strong CP problem and are an excellent dark matter candidate, and their generalization to axion-like particles. We also review dark photons and other dark-sector particles, including sub-GeV dark matter, which are theoretically natural, provide for dark matter candidates or new dark matter interactions, and could resolve outstanding puzzles in particle and astro-particle physics. In many cases, the exploration of dark sectors can proceed with existing facilities and comparatively modest experiments. A rich, diverse, and low-cost experimental program has been identified that has the potential for one or more game-changing discoveries. These physics opportunities should be vigorously pursued in the US and elsewhere.

hep-ph↗

arXiv2013

The quest for axions and other new light particles

Standard Model extensions often predict low-mass and very weakly interacting particles, such as the axion. A number of small-scale experiments at the intensity/precision frontier are actively searching for these elusive particles, complementing searches for physics beyond the Standard Model at colliders. Whilst a next generation of experiments will give access to a huge unexplored parameter space, a discovery would have a tremendous impact on our understanding of fundamental physics.

hep-ph↗

arXiv2013

IAXO - The International Axion Observatory

The International Axion Observatory (IAXO) is a next generation axion helioscope aiming at a sensitivity to the axion-photon coupling of a few 10^{-12} GeV^{-1}, i.e. 1-1.5 orders of magnitude beyond sensitivities achieved by the currently most sensitive axion helioscope, the CERN Axion Solar Telescope (CAST). Crucial factors in improving the sensitivity for IAXO are the increase of the magnetic field volume together with the extensive use of x-ray focusing optics and low background detectors, innovations already successfully tested at CAST. Electron-coupled axions invoked to explain the white dwarf cooling, relic axions, and a large variety of more generic axion-like particles (ALPs) along with other novel excitations at the low-energy frontier of elementary particle physics could provide additional physics motivation for IAXO.

physics.ins-det↗

arXiv2010

Notes from the 3rd Axion Strategy Meeting

In this note we briefly summarize the main future targets and strategies for axion and general low energy particle physics identified in the "3rd axion strategy meeting" held during the AXIONS 2010 workshop. This summary follows a wide discussion with contributions from many of the workshop attendees.

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