We report the first search for dark sectors performed at the NA64 experiment employing a high energy muon beam and a missing energy-momentum technique. Muons from the M2 beamline at the CERN Super ...Proton Synchrotron with a momentum of 160 GeV / c are directed to an active target. The signal signature consists of a single scattered muon with momentum < 80 GeV / c in the final state, accompanied by missing energy, i.e., no detectable activity in the downstream calorimeters. For a total dataset of ( 1.98 ± 0.02 ) × 10 10 muons on target, no event is observed in the expected signal region. This allows us to set new limits on the remaining ( m Z ′ , g Z ′ ) parameter space of a new Z ′ ( L μ − L τ ) vector boson which could explain the muon ( g − 2 ) μ anomaly. Additionally, our study excludes part of the parameter space suggested by the thermal dark matter relic abundance. Our results pave the way to explore dark sectors and light dark matter with muon beams in a unique and complementary way to other experiments. Published by the American Physical Society 2024
We discuss new physics phenomenology of hidden scalar ( S ), pseudoscalar ( P ), vector ( V ) and axial-vector ( A ) particles coupled to nucleons and leptons, which could give contributions to ...proton charge radius, ( g − 2 )μ, 8Be − 4He anomaly and electric dipole moment (EDM) of Standard Model (SM) particles. In particular, we estimate sensitivity of NA 64μ experiment to observe muon missing energy events involving hidden scalar and vector particles. That analysis is based on geant4 Monte Carlo simulation of the signal process of muon scattering off target nuclei μN → μN S (V) followed by invisible boson decay into dark matter (DM) particles, S ( V ) → χ χ . The existence of light sub-GeV bosons could possibly explain the muon ( g − 2 ) anomaly observed. We also summarize existing bounds on ATOMKI X 17 ( JP = 0−, 1±) boson coupling with neutron, proton, and electron. We implement these constraints to estimate the contribution of P, V. and A particles to proton charge radius via direct 1-loop calculation of Sachs form factors. The analysis reveals the corresponding contribution is negligible. We also calculate bounds on dark axion portal couplings of dimension-five operators, which contribute to the EDMs of leptons and neutron.
The search for new comparably light (well below the electroweak scale) feebly interacting particles is an exciting possibility to explain some mysterious phenomena in physics, among them the origin ...of Dark Matter. The sensitivity study through detailed simulation of projected experiments is a key point in estimating their potential for discovery.
Several years ago we created the DMG4 package for the simulation of DM (Dark Matter) particles in fixed target experiments. The natural approach is to integrate this simulation into the same program that performs the full simulation of particles in the experiment setup. The Geant4 toolkit framework was chosen as the most popular and versatile solution nowadays.
The simulation of DM particles production by this package accommodates several possible scenarios, employing electron, muon or photon beams and involving various mediators, such as vector, axial vector, scalar, pseudoscalar, or spin 2 particles. The bremsstrahlung, annihilation or Primakoff processes can be simulated.
The package DMG4 contains a subpackage DarkMatter with cross section methods weakly connected to Geant4. It can be used in different frameworks.
In this paper, we present the latest developments of the package, such as extending the list of possible mediator particle types, refining formulas for the simulation and extending the mediator mass range. The user interface is also made more flexible and convenient.
In this work, we also demonstrate the usage of the package, the improvements in the simulation accuracy and some cross check validations.
Program title: DMG4
CPC Library link to program files:https://doi.org/10.17632/cmr4bcrj6j.1
Licensing provisions: GNU General Public License 3
Programming language: c++
Journal reference of previous version: Comput. Phys. Commun. 269 (2021) 108129
Does the new version supersede the previous version?: Yes
Reasons for the new version: Numerous developments, addition of new features
Summary of revisions: WW approximation cross sections for the muon beam are implemented and cross-checked, models with semivisible A′ (inelastic Dark Matter) and spin 2 mediators are added. The range of possible mediator masses is extended. Several important improvements for the annihilation processes are made, the number of possible annihilation processes is extended. User interface is improved. Several bugs are fixed.
Nature of problem: For the simulation of Dark Matter production processes in fixed target experiments a code that can be easily integrated in programs for the full simulation of experimental setup is needed.
Solution method: A fully Geant4 compatible DM simulation package DMG4 was presented in 2020. We present numerous further developments of this package.
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 \(10^{-6}~\mbox{eV} \lesssim m_a \lesssim 5 \times 10^{-5}~\mbox{eV}\).
Objective: to conduct a critical analysis of the existing definitions of artificial intelligence and develop an authors’ version of the concept acceptable for legal sciences.Methods: the ...methodological basis of the study is a set of scientific cognition methods, including abstract-logical method, comparison and correlation analysis.Results: the main regularities of decision-making by artificial intelligence are identified; the mechanism of its perception of objective reality is determined; the fundamental ability of machine learning to conform its behavior to socially acceptable processes is confirmed. It is assumed that there are many ways to describe artificial intelligence: by indicating the action mechanism, the basic operation principles, the range of tasks to be solved, etc. However, the most convincing and consistent is position of those researchers who tend to describe the AI phenomenon by designating its properties and characteristics. The authors state that there is no definition of “artificial intelligence” in the modern legal doctrine. As a result of a comprehensive analysis of various scientific sources in a systematic unity with own judgments, it is proposed to introduce the author’s version of the “artificial intelligence” concept into scientific circulation.Scientific novelty: the paper presents an assessment of the “artificial intelligence” concept definitions available in the scientific literature and legal framework, as well as the authors’ opinion on their relevance, comprehensiveness and topicality; there is an attempt to formulate the definition taking into account all the significant properties of artificial intelligence.Practical significance: is due to the current impossibility to apply legal norms and rules to relations involving artificial intelligence taking into account their specifics. The main provisions and conclusions of the study can be used to improve the mechanisms of legal regulation of artificial intelligence in the Russian Federation.
We discuss the thermal target curves of Majorana, Dirac, scalar and vector light dark matter (DM) that are associated with the freeze-out mechanism via the annihilation into \(e^+e^-\) pair through ...the electron-specific spin-0 mediator of dark matter. We also discuss the mechanism to produce the regarding DM mediator in the electron (positron) fixed-target experiments such as NA64e and LDMX. We derive the corresponding experimental reaches of the NA64e and LDMX that are complementary to the DM thermal target parameter space.
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