arXiv subjects
Publications and source records attributed to K. Jungmann.
A new highly sensitive method of looking for electric dipole moments of charged particles in storage rings is described. The major systematic errors inherent in the method are addressed and ways to minimize them are suggested. It seems possible to measure the muon EDM to levels that test speculative theories beyond the standard model.
In this paper a new method is presented for particles in storage rings which could reach a statistical sensitivity of 10**(-27) e cm for the deuteron EDM. This implies an improvement of two orders of magnitude over the present best limits on the T-odd nuclear forces ksi parameter.
Upon a suggestion of Kostelecky et al., we have performed a test of CPT and Lorentz invariance from the microwave spectroscopy of muonium. New terms in their standard model extension violating CPT and Lorentz symmetry would appear as anti-correlated frequency shifts, oscillating at the earth's sidereal frequency, in the two ground state hyperfine transitions involving muon spin flip, $ν_{12}$ and $ν_{34}$, which were measured in a strong magnetic field of 1.7 T. No such time dependence was observed in $ν_{12}$ or $ν_{34}$ at the level of 20 Hz, limiting the size of some CPT and Lorentz violating parameters with Planck scale sensitivity, and representing almost an order of magnitude improvement over previous limits for the muon.
The physics potential of an intense source of low-energy muons is studied. Such a source is a necessary stage towards building the neutrino factories and muon colliders which are being considered at present. The CERN Neutrino Factory could deliver muon beams with intensities 3-4 orders of magnitude higher than available now, with large freedom in the choice of the time structure. Low-energy muon physics contributes to many fields of basic research, including rare muon decays, i.e., decays that do not conserve muon number, measurements of fundamental constants, the muon anomalous magnetic moment, determination of the Lorentz structure of the weak interaction, QED tests, CPT tests, proton and nuclear charge distributions (even for short-lived isotopes), and condensed matter physics. In studying the experimental programme, we analyse the present limitations, list the requirements on the new muon beams, and describe some ideas on how to implement these beam lines in a CERN neutrino factory complex.
Following a suggestion of Kostelecky et al. we have evaluated a test of CPT and Lorentz invariance from the microwave spectroscopy of muonium. Hamiltonian terms beyond the standard model violating CPT and Lorentz invariance would contribute frequency shifts $δν_{12}$ and $δν_{34}$ to $ν_{12}$ and $ν_{34}$, the two transitions involving muon spin flip, which were precisely measured in ground state muonium in a strong magnetic field of 1.7 T. The shifts would be indicated by anti-correlated oscillations in $ν_{12}$ and $ν_{34}$ at the earth's sidereal frequency. No time dependence was found in $ν_{12}$ or $ν_{34}$ at the level of 20 Hz, limiting the size of some CPT and Lorentz violating parameters at the level of $2\times10^{-23}$ GeV, representing Planck scale sensitivity and an order of magnitude improvement in sensitivity over previous limits for the muon.
We are proposing a new method to carry out a dedicated search for a permanent electric dipole moment (EDM) of the muon with a sensitivity at a level of 10^{-24} e cm. The experimental design exploits the strong motional electric field sensed by relativistic particles in a magnetic storage ring. As a key feature, a novel technique has been invented in which the g-2 precession is compensated with radial electric field. This technique will benefit greatly when the intense muon sources advocated by the developers of the muon storage rings and the muon colliders become available.
The pressure shifts of the $3s4s^3S_1 \to 3s3p^3P_{0,1,2}$ transition of magnesium atoms immersed in superfluid helium have been measured at $(1.3\pm0.1 )$K between saturated vapour pressure and $24 $bar. The wavelength is blue shifted linearly by $(0.07\pm0.01) \frac{nm}{bar}$. This value can be satisfactorily described in the framework of the standard bubble model.
The muon magnetic anomaly may contain contributions from physics beyond the standard model. At the Brookhaven National Laboratory (BNL) a precision experiment aims for a measurement of the muon magnetic anomaly $a_μ$ to 0.35 ppm, where conclusions about various theoretical approaches beyond standard theory can be expected. The difference between the spin precession and cyclotron frequencies is measured in a magnetic storage ring with highly homogeneous field. Data taking is in progress and part of all recorded data has been analyzed. Combining all experimental results to date yields preliminarily $a_μ(expt)=1~165~921(5) \cdot 10^{-9}$ (4 ppm) in agreement with standard theory.
The 1s-2s interval has been measured in the muonium ({$μ^+e^-$}) atom by Doppler-free two-photon laser spectroscopy. The frequency separation of the states was determined to be 2 455 528 941.0(9.8) MHz in good agreement with quantum electrodynamics. The muon-electron mass ratio can be extracted and is found to be 206.768 38(17). The result may be interpreted as measurement of the muon-electron charge ratio as $-1- 1.1(2.1)\cdot 10^{-9}$.
A new upper limit for the probability of spontaneous muonium to antimuonium conversion was established at ${\rm P_{M\bar{M}}} \leq 8.2 \cdot 10^{-11}$ (90%C.L.) in 0.1~T magnetic field, which implies consequences for speculative extensions to the standard model. Coupling parameters in R-parity violating supersymmetry and the mass of a flavour diagonal bileptonic gauge boson can be significantly restricted. A Z$_8$ model with radiative mass generation through heavy lepton seed and the minimal version of 331-GUT models are ruled out.
A new experiment has been set up at the Paul Scherrer Institut to search for muonium to antimuonium conversion. No event was found to fulfil the requested signature which consists of the coincident detection of both constituents of the antiatom in its decay. Assuming an effective (V-A)$\times$(V-A) type interaction an improved upper limit is established for the conversion probability of ${\rm P_{M\bar{M}}} \leq 8 \cdot 10^{-9}$ (90%C.L.), which is almost two orders of magnitude lower compared to previous results and provides a sensitive test for theoretical extensions of the standard model.
We present ionization probability and line shape calculations for the two-step 3-photon ionization process, $1S \stackrel{2\hbar ω}{\longrightarrow}2S \stackrel{\hbar ω}{\longrightarrow}εP $, of the ground state of hydrogenic atoms in a non-monochromatic laser field with a time--dependent amplitude. Within the framework of a three--level model, the {\it AC Stark} shifts and non-zero ionization rates of all states involved were taken into account together with spatial and temporal inhomogeneities of the laser signal. In contrast with the usual perturbative technique, the time evolution of the atomic states was simulated by direct numerically solving the system of coupled time--dependent inhomogeneous differential equations, being equivalent to the appropriate non-stationary Schrödinger equation. Particular numerical results were obtained for typical parameters of the pulsed laser field that are employed in a new experiment to measure the $1S-2S$ energy separation in muonium at the Rutherford Appleton Laboratory. The shifts and asymmetries of the photoionization line shapes revealed may be of relevance for ultra-high precision experiments in hydrogen in CW laser fields.
A positive muon ($μ^+$) and an electron ($e^-$) form the the hydrogen-like muonium atom ($M$=$μ^+ e^-$). Since it consists of two leptonic particles which are according to present knowledge point-like, accurate calculations of its level energies can be performed in the framework of standard theory. In particular, the theoretical description of this system is possible almost exclusively by Quantum Electrodynamics (QED) which has been verified in various very high precision experiments. Due to the close confinement of the bound state the muonium atom renders in addition the possibility for sensitive searches for electron--muon interactions not included in the standard model. Such exotic processes could affect the energy of the quantum states at a level of the same order of magnitude as the precision achievable in modern spectroscopic experiments.Oscillations between muonium and antimuonium ($\bar{M}$=$μ^- e^+$) would violate separate additive lepton number conservation which is a purely empirical law.
Quantum Electrodynamics describes electromagnetic interactions of free muons and of muon and electron in the muonium atom to very high accuracy. Contributions of other and yet unknown interactions can be investigated in precision experiments, e.g. by searching for muonium-antimuonium conversion and by measuring the muon magnetic anomaly.
The hydrogen-like muonium atom ($μ^+e^-$) consists of a positive muon ($μ^+$) and an electron ($e^-$). Since it was first observed by Hughes et al. in 1960, a series of precision experiments could be carried out testing bound state Quantum Electrodynamics (QED) and the nature of the muon as a point-like leptonic particle. Precision values for fundamental constants could be obtained, including the fine structure constant $α$ and the muon's magnetic moment $μ_μ$. Since no internal structure could be revealed for leptons down to dimensions of $10^{-18}$m, the accuracy of theoretical calculations of term energies is higher than for the natural hydrogen atom and its isotopes deuterium and tritium as well as exotic hydrogen-like systems which contain hadrons. Internal structure effects of these particles spoil the precision of theoretical results. Of particular interest for precision muonium experiments, which are carried out in order to test standard theory and to extract accurate values for fundamental constants, are the ground state hyperfine structure splitting $Δν_{HFS}$ and the 1s-2s interval $Δν_{1s2s}$. Both cases involve the n=1 ground state in which the atoms can be produced in sufficient quantities.
The observed interactions between particles are not fully explained in the successful theoretical description of the standard model to date. Due to the close confinement of the bound state muonium ($M = μ^+ e^-$) can be used as an ideal probe of quantum electrodynamics and weak interaction and also for a search for additional interactions between leptons. Of special interest is the lepton number violating process of sponteanous conversion of muonium to antimuonium.
A new superferric magnetic storage ring with highly homogeneous field at 1.45 T and weak electrostatic focussing is described which has been set up at the Brookhaven National Laboratory (BNL), USA, for a precision measurement of the magnetic anomaly of the muon. The toroidal storage volume has a radius of 7 m and a diameter of 9 cm. Precision magnetic field determination based on pulsed NMR on protons in H$_2$O yields the field to better than 0.1 ppm everywhere within the storage region. Follow on experiments using the setup have been already suggested to search for a finite mass of the muon neutrino and to search for an electric dipole moment of the muon with significantly increased accuracy. The high homogeneity of the field suggests the usage of such devices as a mass spectrometer for heavier particles as well.
A new experimental search for muonium-antimuonium conversion was conducted at the Paul Scherrer Institute, Villigen, Switzerland. The preliminary analysis yielded one event fulfilling all required criteria at an expected background of 1.7(2) events due to accidental coincidences. An upper limit for the conversion probability in 0.1 T magnetic field is extracted as $8 \cdot 10^{-11}$ (90% CL).