At the Paul Scherrer Institut (PSI) muon rates of up several 10$^8$ $\mu^+$/s are available, produced by its 1.4 MW proton accelerator complex HIPA. While these are currently among the highest muon rates available worldwide, projects in the US and Japan are underway that will be able to surpass these intensities by several orders of magnitude.
In order to maintain PSI’s position at the...
The COMET experiment aims at achieving the sensitivity of mu-e coversion search better than 10^-14 in Phase I and better than 10^-16 in Phase II using highly intense pulsed proton beam provided at J-PARC. The COMET experiment plans to start its engineering run in early 2023 followed by physics data acquisition in 2024. In this presentation, we will report the current status and future prospect...
The Mu3e experiment will search for the charged lepton-flavour violation decay of the muon into two positrons and one electron. With a vanishingly small branching ratio in the Standard Model, any observation of this process will be clear evidence for new physics. A first phase of the experiment aiming for a single event sensitivity of one in $2\cdot 10^{15}$ muon decays is currently under...
The baryon asymmetry of the universe points towards CP-violating sources beyond the Standard Model. If these consist of heavy new particles, their effect at low energies can be described by effective field theories. I will describe theoretical challenges and recent progress within this framework for the extraction of bounds on CP violation from neutron EDM searches. In particular, I will...
Electric dipole moments (EDMs) are a convenient low-energy observable with high-energy implications. They induce violations of parity and time-reversal symmetry in atoms and molecules, which lead to experimental signatures that be precisely measured using atomic physics techniques.
I will provide an overview of EDM searches with atoms and molecules, discuss recent developments, and guess at...
The Standard Model is a well-tested and successful theory of particle physics. However, it does not fully explain the lack of anti-matter observed in the universe. A possible mechanism that could explain this is from new sources of CP violation. This could lead to the existence of a permanent electric dipole moment (EDM) in fundamental particles, through beyond Standard Model interactions....
he Nuclear and Particle Physics (NPP) group of the Institut Laue Langevin (ILL) is operating five public instruments providing an international user community competitive and often unique experimental conditions. We operate the PF1B cold neutron facility – the neutron beam with the worldwide highest flux of cold neutrons, including polarization capability and a large, background free...
Despite decades of effort, quantum electrodynamics (QED) is poorly tested in the regime of strong coulomb fields due to a confluence of difficulties linked to experimental limitations in highly-charged ion spectroscopy and nuclear uncertainties. I will present a new paradigm for probing higher-order QED effects using Rydberg states in exotic atoms, where orders of magnitude stronger field...
The muonium atom is a bound state of a positive muon and an electron, and is one of the hydrogen-like atoms which consists purely of leptons. By measuring the muonium hyperfine structure, the muon mass and the magnetic moment ratio of the proton to the muon can be determined. These values are used to determine the experimental value of muon $g-2$, for which a discrepancy of 4.2$\sigma$ between...
I will present our recent measurement of the n=2, Muonium Lamb Shift of 1047.2(2.5) MHz, which comprises an order of magnitude improvement upon the last determinations and matches with theory within one sigma. This allows us to set limits on Lorentz and CPT violation in the muonic sector, as well as on new physics coupled to muons and electrons which could provide an explanation of the muon...
The proton radius puzzle began in 2010 when the CREMA Collaboration released their measurement of the proton radius (Pohl et. al (2010)) from muonic hydrogen spectroscopy: rp=0.84184(67) fm, This was five standard deviations smaller that the accepted CODATA value at that time (0.8768(69) fm), and sparked an enduring and intriguing puzzle. This puzzle has been addressed in repeated electron...
Measurements of the muonic helium atom hyperfine structure (HFS) is a sensitive tool to test three-body atomic system, bound-state quantum electrodynamics (QED) theory, and determine fundamental constants of the negative muon magnetic moment and mass. The world most intense pulsed negative muon beam at J-PARC MUSE gives an opportunity to improve previous measurements and to test further CPT...
Experimental efforts to probe new physics by measuring atomic parity violating transitions in a trapped radium ion require at least $0.2\,\%$ knowledge of the radium nuclear charge radius. An experiment at the Paul Scherrer Institute (PSI), pursued by the muX collaboration, aims to determine for the first time the absolute nuclear charge radii of $\mathrm{^{226}Ra}$ and other radioactive...
The rate of neutron decay can be precisely calculated, using the theory of electroweak interactions, with an uncertainty on the order of 1e-4. Recent measurements using bottled neutrons have achieved uncertainties below 1 s (0.1 %), but other measurements observing neutron decay in flight disagree by 10 s. Attempts to resolve this discrepancy have spawned much experimental effort as well as...
Different methods of measuring the neutron lifetime lead to discrepant results at about 4.5 sigma. These anomalies are maybe related to yet unfixed systematics but they also can be an indication to new physics beyond the Standard Model. In particular, they can be explained by a neutron transformations in dark matter particles, or they could indicate to new non-standard interactions which...
New measurements of the neutron electric dipole moment (nEDM) will place even tighter constraints on theories involving new sources of CP violation beyond the standard model. It is believed these are required in order to explain the predominance of matter over antimatter (baryon asymmetry) in the universe. The nEDM constrains new physics scenarios at the TeV scale and beyond which do not...
The Fermilab Muon g-2 (E989) collaboration has published the most precise measurement of the muon anomalous magnetic moment $a_{\mu}$ with an uncertainty of 460 ppb in 2021 based on the Run 1 (2018) dataset. The new experimental world average of $a_{\mu}$ deviates by 4.2 standard deviations from the Standard Model prediction provided by the Muon g-2 Theory Initiative.
Following Run 1,...
The MEG experiment searches for the μ+ → e+ γ decay and has recently set the most stringent upper limit on its branching ratio B(μ+ → e+ γ) < 4.2 10-13 at 90% C.L., based on the full data sample acquired during 2009-2013 years. It is a factor 30 improvement over the previous limit set by the MEGA experiment (B(μ+ → e+ γ)< 1.2 10-11 at 90% C.L.) and also the strongest bound on any forbidden...
T. Hume $^{1, 2, ∗}$
(on behalf of the muEDM Collaboration)
$^1$ ETH Zürich, 8093 Zürich, Switzerland
$^2$ Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
The current limit on the muon electric dipole moment (muEDM) of $d_\mu<1.8\times10^{-19}\,e\mathrm{cm}\,\,(95\%\,\,\mathrm{C.L.})$[1] could be improved by $\sim10^3$ with a dedicated muEDM Experiment at PSI.
An EDM signal would...
on behalf of the nEDM collaboration
In the n2EDM experiment, the measurement of the neutrons spin state is required. Neutrons are first fully polarised in a super conducting magnet and then subjected to a magnetic field of 1 μT and a strong electric field (around 15 kV/cm). The goal is to measure the neutrons precession frequency and to assess the possible frequency shift induced by the...
The Muon g-2 collaboration has published the most precise measurement of the muon anomalous magnetic moment a? with an uncertainty of 460 ppb in 2021. The new experimental world average of a? deviates by 4.2 standard deviations from the Standard Model prediction provided by the Muon g-2 Theory Initiative. The emerging results from ab-initio lattice QCD calculations allow scrutiny of this...
**The forward neutron-nucleus scattering amplitude has a $T$-odd, $P$-odd component proportional to $\sigma_n \cdot I \times k_n$. Thus the double spin-dependent neutron absorption cross section is a suitable observable in which to search for a new source of CP-violation needed to explain the baryon asymmetry of the universe. Unlike other complementary observables such as the electric dipole...
D. K.-T. Wong, M. T. Hassan, J. F. Burdine, T. E. Chupp, S. M. Clayton, C. Cude-Woods, S. A. Currie, T. M. Ito, C.-Y. Liu, M. Makela, C. L. Morris, C. M. O'Shaughnessy, A. Reid, N. Sachdeva, W. Uhrich
The neutron electric dipole moment (nEDM) experiment that is currently being developed at Los Alamos National Laboratory (LANL) will use ultracold neutrons (UCNs) and Ramsey's method of...
Due to the large overlap between the muon and nuclear wave function, muonic atoms are an exceptionally sensitive system to study short range muon-nuclear/nucleon interactions and probe various nuclear moments. With a physics program focusing on Atomic Parity Violation (APV), the muX collaboration is performing a series of muonic X-ray measurements in medium- and high-Z nuclei, exploiting the...
The energy spectrum of ultracold neutrons (UCN) is an important factor in determining the systematic effects in precision measurements utilizing UCNs. We performed UCN energy spectrum measurements in a large storage tank filled by the PSI UCN source and studied its time evolution using OTUS - an oscillating spectrometer [1]. The obtained results will be compared to the TOF method and a...
Neutron Electric Dipole Moment searches typically compare spin precession of trapped ultra-cold neutrons (UCN) with a stable clock, in an applied high electric field. One approach to limit systematic uncertainties in this type of experiment employs two storage chambers, allowing for simultaneous differential measurements with two electric field orientations. In PanEDM [1] this approach is...
The standard model of particle physics cannot explain the origin of the accelerating expansion of the universe or the hierarchy problem of gravity. Theories beyond the standard model of physics created to solve these problems often also predict the existence of a fifth fundamental force. We search for the existence of a fifth force using neutron pendellösung interference, where the neutron...
The type-I seesaw model is probably the most straightforward and best studied extension of the Standard Model that can account for the neutrino masses determined from neutrino oscillation data. We study the symmetry-protected type-I seesaw, in which the Wilson coefficient of the Weinberg operator is set zero such that sizeable neutrino Yukawas are permissible that can lead to relevant effects...
High precision experiments using muons (μ+) and muonium atoms (μ+e−) offer promising opportunities to test theoretical predictions of the Standard Model in a second-generation, fully-leptonic environment. Such experiments including the measurement of the muon g-2, muonium spectroscopy and muonium gravity would benefit from intense high-quality and low-energy muon beams.
At the Paul Scherrer...
We perform the one-loop renormalization of the low-energy effective field theory (LEFT) in the 't Hooft-Veltman (HV) scheme for $\gamma_5$. We extend the LEFT operator basis by the required set of evanescent operators. Instead of using a pure $\overline{\textrm{MS}}$ procedure, we renormalize physical operators such that they absorb the finite effects from insertions of evanescent operators as...
The n2EDM experiment, which is currently under construction at the Paul Scherrer Institute (PSI), is designed to improve the sensitivity of the neutron electric dipole moment by an order of magnitude.
In order to achieve this goal, it is crucial to stabilize the magnetic fields inside the precession chamber, where neutrons are stored and Ramsey measurements are performed.
For this...
The large enhancement of parity-violation of the weak interaction was found in nuclear reactions for several nuclei [1]. The enhancement is explained as the mixing of parity-unfavored partial amplitudes in the entrance channel of the compound sates, s-p mixing [2]. It is proposed that the time-reversal symmetry violation is also enhanced in compound nuclei by the same mechanism [3]. We are...
Metallic magnetic microcalorimeters (MMCs) represent a promising detection method for broadband high-resolution x-ray spectroscopy. These systems are particularly suitable for the detection of low-energy x-rays, as found in the spectroscopy of low-Z muonic atoms. Such high-resolution spectra would enable precision measurements of charge radii of light nuclei and could thus provide important...
Pseudoscalar pole diagrams are the numerically dominant component of the HLbL contribution to the muon $g-2$. We report on our computation of the pion and eta pole contributions from twisted mass lattice QCD at physical quark masses. Pion and eta transition form factors to two photons are the key intermediate quantity required to derive these contributions; on the lattice, we have access to a...
Cs magnetometer based current source for permanent neutron electric dipole moment measurement
Ren Li$^1$, Judith Vankeirsbilck$^1$, Reza Tavakoli-Dinani$^1$, Nathal Severijns$^1$
$^1$ Instituut voor Kern- en Stralingsfysica, University of Leuven
(on behalf of the nEDM collaboration)
A non-zero permanent Electric Dipole Moment (EDM) in elementary A non-zero permanent Electric Dipole...
The n2EDM experiment at PSI's Ultracold Neutron source aims at searching for the permanent neutron electric dipole moment with a sensitivity of about $1 \times 10^{-27}$ ecm with the baseline setup. In order to correct for first order magnetic field drifts and gradients when using Ramsey’s method of separated oscillating field with ultracold neutrons, this experiment requires a precise...
The measurement of the muon anomalous magnetic moment $a_{\mu}$ is a precision test of the Standard Model and an indirect search for New Physics. The Muon g-2 (E989) collaboration has published the most precise measurement of the muon anomalous magnetic moment with an uncertainty of 460 ppb in 2021, leading to a world average that deviates by 4.2 standard deviations from the Standard Model...
The LEMING experiment aims to measure the free fall of muonium (M $= \mu^+ + e^-$) and thereby testing for the first time the weak equivalence principle using a purely leptonic, second-generation antimatter dominated system. Such a direct measurement requires a high-intensity, low-emittance M beam. We have demonstrated the working principle of this novel M beam by stopping accelerator muons in...
The MEG II experiment searches for the charged lepton flavor violation process, $\mu\rightarrow e^+ +\gamma$, with the target sensitivity of branching ratio : O(10$^{-14}$).
Gamma-rays are detected by the liquid xenon detector to reconstruct their energy, timing, and position. In the liquid xenon detector, 4092 VUV-sensitive MPPCs produced by Hamamatsu photonics are used. Decrease of photon...
The LEMING experiment aims to test the equivalence principle for second-generation matter, using a cold muonium beam (bound μ+e−), where the inertial mass is dominated by the muon.
The feasibility of such a measurement relies on measuring the gravitational deflection of a lifetime-limited atomic beam. In this poster, the feasibility of an atomic interferometer is discussed, which could...
Limiting the value of the permanent electric dipole moment on the electron (eEDM) provides a sensitive probe of the Standard Model of particle physics and its extensions. The current best limit on the eEDM is $|d_e| < 1.1 \times 10^{-29}~\it{e}~\rm{cm}$ [1] using ThO, while experiments have been performed using a number of different atoms and molecules. In our experiment a supersonic source of...
The muEDM experiment at PSI aims to search for the muon electric dipole moment with unprecedented sensitivity. The muon is first injected into a solenoid storage ring, and then a pulsed magnetic field is used to kick the muon onto a stable orbit. To this end, a fast signal is required to trigger the magnetic field, and this is provided by a muon entrance detector consisting of an ultra-thin...
The Mu3e experiment at the Paul Scherrer Institute (PSI) searches for the charged lepton flavour violating decay $\mu^+ \rightarrow e^+ e^+ e^-$.
The experiment aims for an ultimate sensitivity of one in $10^{16}$ $\mu$ decays.
The first phase of the experiment, currently under construction, will reach a branching ratio sensitivity of $2\cdot10^{-15}$ by observing $10^{8}$ $\mu$ decays per...
The High-Intensity Muon Beams (HIMB) project aims to increase the rate of the intensity muon beamlines at Paul Scherrer Institute (PSI) by two orders of magnitude up to 10^10 µ+/s, with a significant impact on low-energy, high-precision muon-based experiments. This is done by improving the surface muon yield with a new target geometry and by increasing capture and transmission with...
Ultralight Axions and axion-like particles are important dark matter candidates. If they are responsible for a significant proportion of dark matter, and are thus present in a large number density, they can be viewed as a galactic-scale classical field oscillating at a frequency proportional to their mass m$_a$. Interactions of a coherently oscillating axion dark matter field with gluons could...
The MEG II experiment searches for $\mu\to e\gamma$ decay which is one of the charged lepton flavor violation decays. The discovery of this decay will be clear evidence of new physics beyond the Standard Model. The liquid xenon (LXe) gamma-ray detector is one of the subdetectors in the MEG II experiment. It measures the energy, position and timing of the gamma-ray from $\mu\to e\gamma$. The...
The High Intensity Muon Beams (HIMB) project at the Paul Scherrer Institute (PSI) will provide an unprecedented rate of 1e10 muons/sec to next-generation intensity frontier particle physics and material science experiments. As part of our work on the beamline design optimisation for the HIMB, we used differential-algebraic transfer maps with system knobs computed using the code COSY INFINITY...
In this poster presentation, I will discuss the two-photon exchange (TPE) as a crucial higher-order contribution to lepton-proton scattering and the theory of light muonic atoms. In particular, I will focus on the proton polarizability contribution as the dominant uncertainty in the theory prediction of the Lamb shift and the hyperfine splitting (HFS) in muonic hydrogen ($\mu$H). It is...
A new source of ultracold neutrons (UCNs), developed at the Institut Laue-Langevin (ILL) and named SuperSUN, is currently being commissioned. The source converts the cold neutrons, delivered by ILL's existing beam H523, to UCNs in a vessel filled with isotopically pure superfluid helium-4, wherein the inelastic scattering process transfers the neutron's energy and momentum to phonons in the...
Neutron grating interferometers can be employed as powerful tools to perform high-precision measurements of deflection angles and scattering. A novel concept of a symmetric Talbot-Lau interferometer using absorption gratings is under development at the University of Bern. The ultimate goal of this project will be a sensitive measurement of the neutron electric charge. Currently, a...
Extracting particle physics properties from neutrinoless double-beta (0nßß) decay requires a detailed understanding of the involved nuclear structures. Still, modern calculations of the corresponding nuclear matrix elements (NMEs) differ by factors 2-3.
The high momentum transfer of Ordinary Muon Capture (OMC) provides insight into highly excited states similar to those that contribute...
The HOLMES experiment aims to measure directly the neutrino mass with a calorimet- ric approach studying the end point of the 163Ho electron-capture decay spectrum. This isotope is produced via neutron capture by 162Er and its very low Q-value (2.8 keV) makes it a very good choice but introduces two critical aspects. The first one is the need to embed the isotope inside the cryogenic...
A high-fidelity simulation is crucial in the study of systematic errors arising from beam dynamics and detector acceptance in the Muon g-2 experiment at Fermilab. Gm2ringsim, our current Geant4-based simulation package is computationally expensive and has limited the amount of dataset that can be produced for various systematic studies. We propose a “divide and conquer” approach, where the...
A free neutron decays into a proton, an electron, and an antineutrino in a lifetime of about 880 s. The lifetime is an important parameter for particle physics and astrophysics. For example, the abundance ratio of light elements in the early universe in the Big Bang nucleosynthesis is determined using the neutron lifetime, and the lifetime also determines the Vud term of the...
Symmetry under the combined charge and parity (CP) transformations is only known to be viola tedthrough mixing matrices in the Standard Model. This leads to vanishingly small effects in many low energy processes. Positronium (Ps) is a purely leptonic bound state that decays to photons. Any observation of CP violation in Ps would indicate beyond Standard Model physics. We are designing an...
The qBounce collaboration successfully commissioned a new Ramsey-type gravitational resonance spectroscopy (GRS) setup at the Institute Laue-Langevin (Grenoble). This increases the achievable sensitivity significantly with respect to previous implementations. In 2018, we measured the gravitational state transitions with the new setup. This Ramsey-type implementation is not only sensitive to a...
The Mu3e experiment will search for the lepton flavour violating decay $\mu^+ \rightarrow e^+ e^- e^+$ and is aiming for a sensitivity of one in $10^{16}$ muon decays. Since this decay is highly suppressed in the Standard Model to a branching ratio of below $\mathcal{O}(10^{−54})$, an observation would be a clear sign for new physics.
In the Mu3e detector, four layers of silicon pixel...
Using the McMule framework, we present fully differential predictions for the process $e^+e^- \to \mu^+ \mu^-, \tau^+ \tau^-$ with polarised initial states, including the dominant QED corrections at NNLO. Weak corrections are included at NLO in an effective field theory approach. This calculation is important for a wide range of experiments measuring the $R$ ratio (e.g. Daphne, VEPP, ...) or...
The amazing evolution of precision in recent Penning-trap experiments is driving the need for ever-improving cooling techniques. In this talk, the prospect of a new sympathetic cooling technique using an electron-plasma coupled to a single highly charged ion is presented. Utilizing the synchrotron-radiation of electrons in a strong magnetic field enables cooling to very low motional quantum...
Precision experiments in the hydrogen atom have a long tradition and extensive studies of transitions between low lying $n\leq12$ states were carried out [1$-$6]. These measurements can be used to determine values of the Rydberg constant and the proton charge radius. We present a new experimental approach to perform measurements of transition frequencies between the metastable 2s...
The uniformity of the magnetic field inside the inner part of the n2EDM experiment is a crucial condition to achieve the desired sensitivity of $10^{-28} e \ cm$ for the neutron electric dipole moment (EDM). The magnetic-field mapper is a dedicated nonmagnetic robot designed to measure the magnetic field at any point of a large cylindrical volume ($0 \le \rho \le 780 \ mm$, $0 \le \phi \le 360...
A permanent electric dipole moment (EDM) in any elementary particle implies CP symmetry violation and thus could help explain the baryon asymmetry in the universe. Within the Standard Model (SM), the muon EDM is extremely small (~10$^{-42}$ e cm) and therefore any detected signal is a strong hint of new physics beyond the SM. In the Muon g-2 experiment at Fermilab, we aim to perform a more...
A neutron interferometer is a device that splits the wavefunction of a single neutron into two paths, superimposes them, and detects the potential difference between the two paths as a phase difference. Neutron interferometers were practically used in the 1970s, and have contributed greatly to the development of quantum mechanics, such as the verification of spinors and the phase shift of...
Should muon-to-electron conversion in the field of a nucleus be found in the current generation of experiments, the measurement of the atomic number dependence of the process will become an important experimental goal. We present a new treatment of the (Z,A) dependence of muon-to-electron conversion. Our approach differs from earlier work in that it combines nuclear charge distribution...
The $\tau$SPECT experiment aims at measuring the free neutron lifetime, which is a key ingredient for high-precision tests of the Standard Model of Particle Physics and is also fundamental for understanding the production of light elements during the Big Bang Nucleosynthesis.
Neutrons with energies in the range of tens of nano electronvolts are loaded by spin flipping into the tSPECT...
The search for charged Lepton Flavour Violation in muon decays is a key tool to test the Standard Model at the intensity frontier. The MEG II and Mu3e experiments at PSI are respectively designed to detect $\mu \to e \gamma$ and $\mu \to eee$ with an unprecedented accuracy. Moreover, both experiments are competitive in searching for muon decays involving an invisible axion-like particle $X$....
The $^3$He/$^{129}$Xe co-magnetometer is a high precision experiment that can address a variety of fundamental questions including the measurement of the \textit{CP}-violating permanent electric dipole moment (EDM) of the $^{129}$Xe atom, looking for a violation of Lorentz Invariance, and searching for a spin-dependent \textit{P}- and \textit{CP}-violating nucleon-nucleon interaction mediated...
Ever since the discovery of accelerated expansion, the cosmological standard model Lambda-CDM has been our best description of the universe on large scales. In recent years, however, significant tensions have appeared that cast doubt on the validity of dark matter being a cold non-interacting fluid, and the cosmological constant being a global parameter. Moreover, searches for weakly...
The abundant production of beauty and charm hadrons in the $5\cdot 10^{12}$ Z boson decays expected at FCC-ee offers outstanding opportunities in flavour physics that exceed those available at Belle II by a factor of 20, and are complementary to the LHC heavy-flavour programme. A wide range of measurements will be possible in heavy-flavour spectroscopy, rare decays of heavy-flavoured...
Precision measurements in nuclear beta decay have proven in the past years their capability to search for new physics beyond the standard model (SM), by looking for deviations of certain sensitive observables away from their SM predictions. The study of the full beta energy spectrum offers a great medium for probing these observables and thus searching for new physics.
The long-term goal of...
The advent of silicon detectors with an internal gain mechanism has opened new avenues in the field of low-energy precision physics. However, these sensors need to be modified before they can be used in the field of precision low-energy physics. One sensor, with such modifications, is the so-called pLGAD (proton Low Gain Avalanche Detector) [1]. The sensor stems from the iLGAD (inverse Low...
The SUN-2 source [1] at the Institut Laue-Langevin (ILL) is a prototype source of ultracold neutrons (UCN) that converts cold neutrons into UCN via downscattering in superfluid helium. UCN, which have kinetic energies on the order of hundreds of nanoelectronvolts, can be trapped in material-walled storage vessels and used, for example, in experimental searches for the neutron electric dipole...
In the Paul Scherrer Institute, we operate a solid deuterium moderated Ultracold Neutron (UCN) source. UCNs are storable for several minutes, which makes them suitable for measuring neutron properties.
The UCN source will be used in the n2EDM experiment, which will measure the neutron electric dipole moment. This is CP violating and could help explain the Baryon Asymmetry of the...
ACCELERATION EFFECT IN QUANTUM MECHANICS AND NEUTRON OPTICS
A.I. Frank, M.A. Zakharov and G.V. Kulin
Joint Institute for Nuclear Research, Dubna, Russia.
frank@nf.jinr.ru
The report is devoted to the problem of interaction of neutrons with accelerating objects. As was recently shown [1], the previously known Accelerating Matter Effect (AME) [2], is only a special case...
The n2EDM experiment searching for the neutron electric dipole moment is currently being commissioned at PSI. Essential for a tenfold sensitivity improvement relative to the current best result is a uniform magnetic field ($\sigma(B_z) < 170$pT). Any localized magnetic contamination of the apparatus may result in a systematic error of the measurement.
Parts in the direct vicinity of the...
Due to the close bond between orbiting muon and nucleus, the energy levels of muonic atoms are highly sensitive to effects of the nuclear structure. In order to study the magnetic structure of the proton, we are preparing a measurement of the ground-state hyperfine splitting in muonic hydrogen ($\mu$p) at Paul Scherrer Institute (PSI). In this experiment, $\mu$p atoms diffuse through a...
The neutron Electric Dipole Moment (EDM) has attracted interest as a promising channel for finding new physics for a long time. The existence of a neutron EDM would violate CP symmetry given CPT conservation. This new source of CP violation could explain the baryon asymmetry of the universe. The BeamEDM experiment aims to measure the neutron EDM using a novel technique which overcomes the...
The discovery of an electric dipole moment (EDM) of the muon would break time invariance and violate the combined symmetry of charge and parity (CP), shedding light on the imaginary parts of coupling constants in the muon sector of beyond standard model physics (BSM). A search for a muon EDM is an exciting test of the standard model complementary to the recently reported combined 4.2σ...
At the Paul Scherrer Institute we are developing of a high precision instrument to measure the muon electric dipole moment (EDM) using the frozen-spin technique. The presence of a permanent EDM in an elementary particle implies Charge-Parity symmetry violation and, within the context of the Standard Model, the electric dipole moment of elementary particles is extremely small. However, many...
Many theoretical models that expand boundaries of the Standard Model of elementary particles predict the existence of the hidden sector of particles, which can very weakly interact with the visible sector of Standard Model particles. The exchange of virtual particles characterizes a new type of spin-spin interactions, which are different from the well-known electromagnetic ones. The Authors of...
The PERC facility is currently under construction at the FRM II in Garching, Germany. It will serve as an intense and clean source of electrons and protons from neutron beta decay for precision studies. It aims to improve the measurements of the properties of weak interaction by one order of magnitude and to search for new physics via new effective couplings.
PERC's central component is a 12...
The PERC (Proton Electron Radiation Channel) instrument is a neutron decay facility currently being set up at the research reactor FRM II of the Heinz Maier-Leibnitz Zentrum in Garching. Its main component is a 12-meter long superconducting magnet system, which was recently delivered to the FRM II.
We aim to measure several correlation coefficients in neutron beta decay one order of...
Clathrate hydrates [1] are water-based solids with large unit cells that show promise as potential moderators for use in the development of new, more intense sources of very cold neutrons (VCN). Such sources have the potential to enhance existing neutron scattering techniques, and to increase the reach of particle physics experiments that employ beams of slow neutrons. These include...
The neutron electric dipole moment experiment at the Spallation Neutron Source (nEDM@SNS) will implement a novel method, which utilizes polarized ultra-cold neutrons (UCN) and polarized $^3$He in a bath of superfluid $^4$He, to place a new limit on the nEDM down to 2-3$\times$10$^{-28}$ e·cm. The experiment will employ a cryogenic magnet and magnetic shielding package to provide the required...
Non-commutativity of a class of space-time, called $\kappa$-Minkowski, corresponds to curvatures of the momentum space.
In the rigorous treatment of fields on $\kappa$-Minkowski space and using the concept of antipode, one can find actions of discrete symmetries C, P, and T on fields and explicitly derive a subtle difference between Lorentz transformations of particles and antiparticles,...
The Mu3e experiment searches for the lepton flavor violating decay $\mu^+\rightarrow e^+e^-e^+$ with an ultimate aimed sensitivity of $1$ event in $10^{16}$ decays.
For this goal a very high momentum resolution is required.
This goal can only be achieved by reducing the material budget per tracking layer to $X/X_0 \approx 0.1\,\%$ and by using gaseous helium as coolant, a novelty for...
Lepton-flavor-violating decays of light pseudoscalars, $P=\pi^0,\eta,\eta'\to\mu e$, are stringently suppressed in the Standard Model up to tiny contributions from neutrino oscillations, so that their observation would be a clear indication for physics beyond the Standard Model. However, in effective field theory such decays proceed via axial-vector, pseudoscalar, or gluonic operators, which...
We evaluate the exact two-photon exchange (TPE) correction to the unpolarized elastic lepton-proton scattering at small momentum transfer using a low energy effective field theory, heavy baryon chiral perturbation theory. The infrared divergent four- point box diagram with one heavy proton propagator is evaluated analytically via dimensional regularization. We present a numerical comparison of...
The Matter’s Origin from RadioActivity (MORA) project focuses on ion manipulation in traps and laser orientation methods for the searches for New Physics (NP) in nuclear beta decay, aimed at explaining the matter-antimatter asymmetry observed in the Universe.
Precision experiments studying nuclear decay complement high-energy physics measurements searching for signatures of physics beyond...
Recent developments in the muon $g-2$ anomaly may bring about a renaissance of $\mu$ (and $\tau$) physics. The anomaly can be accounted for in the general two Higgs doublet model (without ad hoc $Z_2$ symmetry) via one-loop exchange of nondegenerate scalar $H$ and pseudoscalar $A$ bosons that have flavor changing neutral Yukawa couplings $\rho_{\tau\mu}$ and $\rho_{\mu\tau}$ at $\sim...
The Systematic and Operations Studies (SOS) for the neutron electric dipole moment (nEDM) experiment at the Spallation Neutron Source (SNS) will measure the trajectory correlation functions of $^{3}He$ and neutrons in order the determine the expected frequency shift from the geometric phase effect in the nEDM@SNS experiment. To this end the SOS apparatus will utilize Metastability Exchange...
Recently, various indications of lepton non-universality have been remarked in semileptonic $B$ meson decay processes, both in the neutral-current ($b \to s ll $) and charged-current ($b \to c l \bar \nu_l$) transitions. Influenced by these fascinating quotients, we examined the semileptonic decays involving the $b \to c l \nu_l$ quark level transitions. We executed it through a model...
The GERmanium Detector Array (GERDA) experiment at the Laboratori Nazionali del Gran Sasso (LNGS, Italy) searched for the lepton-number-violating neutrinoless double-beta ($0\nu\beta\beta$) decay of $^{76}$Ge. The potential discovery of such phenomenon would have significant implications in cosmology and particle physics, helping unrevealing the Majorana nature of neutrinos.
The main feature...
(UCNA and UCNτ Collaboration)
Beta decay of a free neutron is the simplest form of "semi-leptonic" weak interaction and is free from nuclear structure effects. Despite the simplicity, the lifetime measurement remains one of the most challenging measurements, bearing different results depending on the technique ("bottle" or "beam") experiment [1, 2]. Another critical measurement from the decay...
Time and frequency are the most accurately measurable quantities in physics. Some optical atomic clocks reach a relative frequency uncertainty close to 10-18 and allow to search for deviations in the predictions of Einstein’s general relativity, test modern unifying theories and to develop new sensors for gravity and navigation.
In my talk, I will introduce the concepts of optical clocks and...
Neutron decay is the prototype for nuclear beta decay and other semileptonic weak interactions. The value of the neutron lifetime and angular correlation coefficients can be used to determine the weak coupling constants $G_A$, $G_V$, and the CKM matrix element $V_{ud}$. Neutron decay was important in the early universe and the lifetime is needed in theoretical calculations of primordial...
Measurements of the neutron electric dipole moment (EDM) occupy an important place in today's particle physics. A finite value of the neutron EDM would indicate time-reversal symmetry violation, and based on the CPT theorem, also CP violation. Hence, it serves as a sensitive probe for CP violation. The current best upper limit of $1.8\times 10^{-26}\,e\cdot\mathrm{cm}$ (90% C.L.) [1] is...
Hadronic contributions to the anomalous magnetic moment of the muon
Interpretation of the recent experimental result for the anomalous magnetic moment of the muon by the Fermilab E989 experiment (and even more so of future updates with yet increased precision) depends crucially on the accuracy of the Standard-Model prediction, especially control over hadronic corrections. In the talk, I...
High-precision Penning trap mass spectrometry is the most precise technique employed to measure masses of nuclides with half-lives as short as a few ten ms. Currently, there are about a dozen high-precision Penning-trap mass spectrometers located in North America and Europe. The majority of them are part of various Rare Ion Beam (RIB) facilities and aim at measurements of masses of...
The LUXE experiment (Laser Und XFEL Experiment) is an experiment in planning at DESY, Hamburg, using the electron beam of the European XFEL. LUXE is intended to study collisions between a high-intensity optical laser pulse and 16.5 GeV electrons from the XFEL electron beam, as well as collisions between the laser pulse and high-energy secondary photons. This will elucidate quantum...
Despite the immense success of the Standard Model (SM), it is well known to be incomplete in describing Nature. Most obviously it is not incorporating gravity, and also falling short in explaining cosmological observations like the baryon asymmetry of the Universe, or the nature of dark matter and dark energy. Recent tensions concerning lepton universality are also persistent in the latest...
In this talk, I will discuss light muonic atoms, with a focus on the theory of two-photon-exchange corrections in muonic hydrogen and deuterium. In addition, I will give a summary of the satellite workshop "Proton structure in and out of muonic hydrogen — the ground-state hyperfine splitting”.
The electric dipole moment of the neutron (nEDM) is exceedingly small in standard model of particle physics. However, beyond standard model theories allow for larger values of the nEDM, possibly within the reach of upcoming experiments. This talk will present an overview and status of the nEDM experiment under development at the Los Alamos National Laboratory (LANL) ultracold neutron source...
Over the last decade, measurements of both b→sl+l- and b→clν decays have consistently shown tensions with Standard Model predictions. These tensions are referred to collectively as the flavour or B anomalies. Key drivers of the flavour anomalies include measurements of Lepton Flavour Universality and of the angular distributions of b→sl+ l-decays. This talk will give an overview of the...
The NA62 experiment at CERN collected the world’s largest data set of charged kaon decays in 2016-2018, leading to the first measurement of the Branching Fraction of the ultra-rare $K^+ –> \pi^+ \nu \nu$ decay. The $K^+→\pi^+\nu\bar{\nu}$ decay was observed with a significance of 3.4$\sigma$, based on 20 candidate events. This measurement also sets limits on BR($K^+→\pi^+X$), where X is a...
An experimental apparatus dedicated to search for the permanent electric dipole moment (EDM) of laser cooled francium atoms has been constructed at RIKEN Nishina Center, Japan. In this talk, the principle of the EDM measurement using francium atoms and the experimental status using the newly built apparatus will be presented.
Neutron and nuclear beta decay correlation coefficients are sensitive to the exotic scalar and tensor interactions that are not included in the Standard Model (SM). The experiment BRAND will measure simultaneously seven neutron correlation coefficients: H, L, N, R, S, U and V that depend on the transverse electron polarization – a quantity which vanishes in the SM. Five of these...
The new g-2 measurement suggests new physics in the anomalous magnetic moment of the muon. While this is related to real part of the corresponding Wilson coefficient, the imaginary part gives rise to an electric dipole moment. In this talk, I show that in models with heavy new physics (i.e. realized above the EW scale) one naturally expect a sizable muon EDM within the reach of the planned PSI...
The J-PARC muon g-2/EDM experiment aims to measure g-2 and EDM of muon by using a reaccelerated thermal muon beam and a compact muon storage magnet at J-PARC MLF muon facility. A new surface muon beamline (H-line) has been partially constructed. The first beam was delivered in January, 2022. Remaining parts of construction are in progress. In this talk, status of the experimental preparation...
The goal of MuSun is a first precise measurement of a weak process in the 2-nucleon (2N) system. These reactions include muon capture on the deuteron, μ + d → n + n + ν, together with two astrophysics reactions of fundamental importance, solar pp fusion and νd reactions. The above interactions involve the same, but poorly known axial-vector coupling at a four-nucleon vertex, which also enters...
The ASACUSA collaboration proposed a hyperfine structure (HFS) measurement on a beam of antihydrogen at the antiproton decelerator of CERN to test CPT invariance. Supporting matter experiments are of high relevance in antihydrogen research. They have been performed for the sigma transition ($F$,$M_F$: 1,0 $\rightarrow$ 0,0) of the hydrogen HFS at 1.42 GHz with the noteworthy precision of 2.7...
Two critical questions in particle physics remain unanswered--what is the particle nature of dark matter, and why is there no antimatter in the universe? Searches for neutron oscillations are an essential component of the worldwide program to understand baryon number violation and what comprises dark matter, but are underexplored experimentally. If dark matter is made up of a rich hidden...
The origin of matter and dark matter might be explained by models invoking copies of the Standard Model, e.g. mirror matter, which are sterile under ordinary Standard Model forces. Previous experiments constrained neutron to mirror neutron (n-n’) oscillations by searching for anomalous neutron losses during the storage of ultracold neutrons (UCN). However, the presence of a mirror magnetic...
The instrument PERKEO III was used to measure most precisely the beta asymmetry in neutron decay at the cold neutron beam line PF1b of the ILL, Grenoble. From this measurement, we extract the ratio of nucleon axial-vector and vector couplings. When combined with the neutron lifetime, this provides the CKM matrix element $V_{ud}$ with only a factor two in precision to the combined result from...
The aSPECT collaboration published in 2020 the most precise value on the electron-antineutrino correlation coefficient $a=-0.10407(82)$ of neutron $\beta$-decay. Meanwhile we revised some systematic errors and reanalysed our data including the Fierz interference term $b$. We will present our new value for $a$, which only marginally differs from our previous published result together with the...
Historically, pion and muon decays have provided essential information regarding nature of the electroweak interactions. In modern times, pions and muons are theoretically studied to a high precision within the extremely well understood Standard Model framework. This simplicity permits pion decays to be used as sensitive probes for physics Beyond the Standard Model (BSM). The comparison of...
A next-generation rare pion decay experiment, PIONEER, is motivated by several inconsistencies between Standard Model predictions and data pointing towards the potential violation of lepton flavor universality. PIONEER will measure the charged-pion branching ratio to electrons vs muons (R_pi), a quantity which is very sensitive to a wide variety of new physics effects - including those at...
Astronomical and cosmological observations strongly suggest that most of the matter in our Universe is non-luminous and made of an unknown substance called Dark Matter. But, currently, it remains invisible and undetectable directly on Earth and makes it one of the greatest mysteries in particle physics. Even if its direct detection escapes to the scientific community in our time, dark matter...
The evidence of dark matter so far is based only on gravitational effects observed at cosmological and astrophysical level. To explain these effects, many theoretical models suggest other non-gravitational very-weak interactions between dark matter and ordinary matter. To test this hypothesis, different experiments are trying to directly produce dark matter at particle accelerators.
The...
The search for neutrinoless double beta (0$\nu\beta\beta$) decay is considered as the most promising way to prove the Majorana nature of neutrinos as well as to give indication on the mass hierarchy and on the absolute mass scale. The discovery of 0$\nu\beta\beta$ decay would moreover open the way for theories predicting the observed matter anti-matter asymmetry of the Universe being a...
At the institute of nuclear physics in Mainz, the Mainz Energy-Recovery Superconducting Accelerator MESA is currently under construction. The talk will discuss the physics program of this new high-intensity facility. The polarized extracted beam will be used for parity-violation experiments with the P2 setup, in particular a precision measurement of the weak mixing angle sin$^2 \theta_W$ in...
The current best estimate for the universe’s matter content consists of 84% dark matter, and the search for its composition remains of great interest. One possible candidate is a so-far undetected ultra-low-mass axion. Various astronomical observations and laboratory experiments constrain the axion mass and its interaction strength in the allowed phase space. In this talk, we report on a...
With the Standard Model (SM) of particle physics undisputedly established and well-tested nevertheless a number of major open questions in modern physics remain. These include the observed asymmetric abundances of matter and antimatter in our known universe after baryogenesis. The NNBAR experiment [1] was proposed to search for baryon number violation (BNV) due to conversion of a neutron (n)...
While neutrino oscillations disprove massless neutrinos, decay kinematics give access to their absolute mass value. Using high-precision tritium beta-decay spectroscopy, the KATRIN experiment places the current best limit on the effective electron anti-neutrino mass at 0.8 eV (90% CL). New operational conditions for an improved signal-to-background ratio, the reduction of systematic...
Cyclotron radiation emission spectroscopy (CRES) is a new avenue towards high-precision measurements of nuclear ?-decay spectra. High energy resolution and intrinsic low background have been demonstrated for CRES. As frequency-based technology CRES has an independent set of systematic uncertainty contributions in comparison to most classical electron spectroscopy techniques. Combined with an...
S. Ulmer$^1$, C. Smorra$^{1,2}$, F. Abbass$^2$, K. Blaum$^3$, M. Bohman$^{1,3}$, M. Borchert1,$^4$, J. A. Devlin$^{1,5}$, S. R. Erlewein$^{1,3,5}$, M. Fleck$^{1,6}$, P. Geissler$^{1,5}, J. I. Jaeger$^{1,3}, B. M. Latacz$^1$, D. Popper$^2$, G. Umbrazunas$^{1,7}$, M. Wiesinger$^{1,3}$, C. Will$^3$, E. J. Wursten$^{1,3}$, Y. Matsuda$^6$, C. Ospelkaus$^4$, W. Quint$^7$, A. Soter$^8$, J....
At CERN, we have recently become able to study atoms of antihydrogen - the antimatter equivalent of hydrogen. The question to be addressed is fundamental and profound: “Do matter and antimatter obey the same laws of physics?” The Standard Model requires that hydrogen and antihydrogen have the same spectrum. The possibility of applying the precision measurement techniques of atomic physics to...
