Search

We report on the electrostatic trapping of neutral SrF molecules. The molecules are captured from a cryogenic buffer-gas beam source into the moving traps of a 4.5 m long traveling-wave Stark decelerator. The SrF molecules in $X^2\Sigma^+(v=0, N=1)$ state are brought to rest as the velocity of the moving traps is gradually reduced from 190 m/s to zero. The molecules are held for up to 50 ms in multiple electric traps of the decelerator. The trapped packets have a volume (FWHM) of 1 mm$^{3}$ and a velocity spread of 5(1) m/s which corresponds to a temperature of $60(20)$ mK. Our result demonstrates a factor 3 increase in the molecular mass that has been Stark-decelerated and trapped. Heavy molecules (mass$>$100 amu) offer a highly increased sensitivity to probe physics beyond the Standard Model. This work significantly extends the species of neutral molecules of which slow beams can be created for collision studies, precision measurement and trapping experiments.

A supersonic beam source for SrF and BaF molecules is constructed by combining the expansion of carrier gas (a mixture of 2% SF6 and 98% argon) from an Even-Lavie valve with laser ablation of a barium/strontium metal target at a repetition rate of 10 Hz. Molecular beams with a narrow translational velocity spread are produced at relative values of Δv/v = 0.053(11) and 0.054(9) for SrF and BaF, respectively. The relative velocity spread of the beams produced in our source is lower in comparison with the results from other metal fluoride beams produced in supersonic laser ablation sources. The rotational temperature of BaF is measured to be 3.5 K. The source produces 6 × 108 and 107 molecules per steradian per pulse in the X2ς+ (ν = 0, N = 1) state of BaF and SrF molecules, respectively, a state amenable to Stark deceleration and laser cooling.

Time-resolved detection of laser-induced fluorescence from pulsed excitation of electronic states in barium monofluoride (BaF) molecules has been performed in order to determine the lifetimes of the $A{\phantom{\rule{0.16em}{0ex}}}^{2}{\mathrm{\ensuremath{\Pi}}}_{1/2}$ and $A{\phantom{\rule{0.16em}{0ex}}}^{2}{\mathrm{\ensuremath{\Pi}}}_{3/2}$ states. The method permits control over experimental parameters such that systematic biases in the interpretation of the data can be controlled to below ${10}^{\ensuremath{-}3}$ relative accuracy. The statistically limited values for the lifetimes of the $A{\phantom{\rule{0.16em}{0ex}}}^{2}{\mathrm{\ensuremath{\Pi}}}_{1/2}(\ensuremath{\nu}=0)$ and $A{\phantom{\rule{0.16em}{0ex}}}^{2}{\mathrm{\ensuremath{\Pi}}}_{3/2}(\ensuremath{\nu}=0)$ states are 57.1(3) and 47.9(7) ns, respectively. Although discrepancies between presently and previously measured lifetimes and theoretical values persist, the ratio of these values is in good agreement with scaling for the different excitation energies. The results serve as a benchmark for current molecular structure calculations. The investigated molecular states are of relevance for an experimental search for a permanent electric dipole moment of the electron in BaF.

We calculate the lifetime of the deuteron with dimension-nine quark operators that violate baryon number by two units. We construct an effective field theory for $|\Delta B|=2$ interactions that give rise to neutron-antineutron ($n$-$\bar{n}$) oscillations and dinucleon decay within a consistent power counting. We calculate the ratio of the deuteron lifetime to the square of the $n$-$\bar{n}$ oscillation time up to next-to-leading order. Our result, which is analytical and has a quantified uncertainty, is smaller by a factor $\simeq 2.5$ than earlier estimates based on nuclear models, which impacts the indirect bound on he $n$-$\bar{n}$ oscillation time and future experiments. We discuss how combined measurements of $n$-$\bar{n}$ oscillations and deuteron decay can help to identify the sources of baryon-number violation.

The role of $\beta$ decay as a low-energy probe of physics beyond the Standard Model is reviewed. Traditional searches for deviations from the Standard Model structure of the weak interaction in $\beta$ decay are discussed in the light of constraints from the LHC and the neutrino mass. Limits on the violation of time-reversal symmetry in $\beta$ decay are compared to the strong constraints from electric dipole moments. Novel searches for Lorentz symmetry breaking in the weak interaction in $\beta$ decay are also included, where we discuss the unique sensitivity of $\beta$ decay to test Lorentz invariance. We end with a roadmap for future $\beta$-decay experiments., Comment: Accepted for publication in Rev. Mod. Phys. 86 pages, 13 figures

A single Ra+ ion stored in a Paul radio frequency ion trap has excellent potential for a precision measurement of the electroweak mixing angle at low momentum transfer and as the most stable optical clock. The effective transport and cooling of singly charged ions of the isotopes Ra-209 to Ra-214 in a gas filled radio frequency quadrupole device is reported. The absolute frequencies of the transition 7s(2)S(1/)2-7d(2)D(3/2) at wavelength 828 nm have been determined in Ra-212-214(+) with ≤19 MHz uncertainty using laser spectroscopy on small samples of ions trapped in a linear Paul trap at the online facility Trapped Radioactive Isotopes: µicrolaboratories for fundamental Physics (TRIµP) of the Kernfysisch Versneller Instituut.

We classify the parity- and time-reversal-violating operators involving quark and gluon fields that have effective dimension six: the quark electric dipole moment, the quark and gluon chromo-electric dipole moments, and four four-quark operators. We construct the effective chiral Lagrangian with hadronic and electromagnetic interactions that originate from them, which serves as the basis for calculations of low-energy observables. The form of the effective interactions depends on the chiral properties of these operators. We develop a power-counting scheme and calculate within this scheme, as an example, the parity- and time-reversal-violating pion-nucleon form factor. We also discuss the electric dipole moments of the nucleon and light nuclei., Comment: Matches published version

Lorentz invariance in the weak interaction has been tested rather poorly compared to the electromagnetic interaction. In this work we show which tests on the weak interaction should be considered. We focus on one particular test that explores the spin degree of freedom in {\beta} decay. To connect various phenomenological tests of Lorentz invariance in the weak interaction, we exploit a new theoretical model that may provide a framework that relates the different tests.

A single trapped Ra + (Z = 88) ion provides a very promising route towards a most precise measurement of Atomic Parity Violation (APV), since APV effects grow faster than Z 3. This experiment promises the best determination of the electroweak coupling constant at the lowest accessible energies. Such a measurement provides a sensitive test of the Standard Model in particle physics. At the present stage of the experiment, we focus on trapping and laser cooling stable Ba + ions as a precursor for radioactive Ra + . Online laser spectroscopy of the isotopes 209 − 214Ra + in a linear Paul trap has provided information on transition wavelengths, fine and hyperfine structures and excited state lifetimes as test of atomic structure calculations. Additionaly, a single trapped Ra + ion could function as a very stable clock.

We explore the breaking of Lorentz and CPT invariance in strong interactions at low energy in the framework of chiral perturbation theory. Starting from the set of Lorentz-violating operators of mass-dimension five with quark and gluon fields, we construct the effective chiral Lagrangian with hadronic and electromagnetic interactions induced by these operators. We develop the power-counting scheme and discuss loop diagrams and the one-pion-exchange nucleon-nucleon potential. The effective chiral Lagrangian is the basis for calculations of low-energy observables with hadronic degrees of freedom. As examples, we consider clock-comparison experiments with nuclei and spin-precession experiments with nucleons in storage rings. We derive strict limits on the dimension-five tensors that quantify Lorentz and CPT violation., Comment: 38 pages, 1 figure, updated to match published version

Possibilities to test the Lorentz invariance of the weak interaction in muon decay are considered. We derive the direction-dependent muon-decay rate with a general Lorentz-violating addition to the W-boson propagator. We discuss measurements of the directional and boost dependence of the Michel parameters and of the muon lifetime as a function of absolute velocity. The total muon-decay rate in the Lorentz-violating standard model extension is addressed. Suggestions are made for dedicated (re) analyses of the pertinent data and for future experiments. Dutch Stichting voor Fundamenteel Onderzoek der Materie (FOM) under Programmes 104 and 114 and project 08PR2636

Searches for permanent electric dipole moments of particles, nuclei, atoms and molecules offer an extraordinary discovery potential to new mechanisms of CP violation beyond those incorporated in the standard electroweak model. The electric dipole moments induced by speculative scenarios, on different physical systems, require a complementary approach to pave the way to the fundamental CP-violating mechanisms. New avenues presently being explored in order to improve the experimental sensitivities include projects that consider the trapping of neutral particles, the confinement of charged particles in storage rings as well as the use of radioactive nuclei. (C) 2011 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

The hyperfine structure of short-lived trapped Ra-211,209(+) ions was investigated by means of laser spectroscopy. The hyperfine structure constants A and B of the 6d(2)D(3/2) level were determined. There is a 2.2 standard deviation difference between the theoretical and the more accurate experimental value for the B coefficient of Ra-211(+). These measurements provide a test for the atomic theory required for upcoming experiments on atomic parity violation and atomic clocks. (C) 2011 Elsevier B.V. All rights reserved.

Atomic parity violation (APV) experiments are sensitive probes of the electroweak interaction at low energy. These experiments are competitive with and complementary to high-energy collider experiments. The APV signal is strongly enhanced in heavy atoms, and it is measurable by exciting suppressed (M1, E2) transitions. The predicted enhancement factor of the APV effect in the S-D transition in Ra(+) is about 50 times larger than the S-S transition in neutral Cs. However, certain spectroscopic information on Ra+, needed to constrain the required atomic many-body theory, was lacking. Using the AGOR cyclotron and the TRI mu P facility at KVI in Groningen, short-lived (212-214)Ra(+) ions were produced and trapped. First ever excited-state laser spectroscopy was performed on the trapped ions. These measurements provide a benchmark for the atomic theory required to extract the electroweak mixing angle to sub 1% accuracy and are an important step towards an APV experiment in a single trapped Ra(+) ion. A lower bound on the radiative lifetime of the 6(2)D(5/2) state was found of 232(4) ms. This experimental confirmation of the long coherence time of the meta-stable 6(2)D(5/2) state is important in light of the possibility of using a single trapped radium ion as an optical frequency standard.

Atomic parity violation (APV) experiments are sensitive probes of the electroweak interaction at low energy. These experiments are competitive with and complementary to high-energy collider experiments. The APV signal is strongly enhanced in heavy atoms, and it is measurable by exciting suppressed (M1, E2) transitions. The predicted enhancement factor of the APV effect in the S-D transition in Ra+ is about 50 times larger than the S-S transition in neutral Cs. However, certain spectroscopic information on Ra+, needed to constrain the required atomic many-body theory, was lacking. Using the AGOR cyclotron and the TRIμP facility at KVI in Groningen, short-lived 212–214Ra+ ions were produced and trapped. First ever excited-state laser spectroscopy was performed on the trapped ions. These measurements provide a benchmark for the atomic theory required to extract the electroweak mixing angle to sub 1% accuracy and are an important step towards an APV experiment in a single trapped Ra+ ion. A lower bound on the radiative lifetime of the 62D5/2 state was found of 232(4) ms. This experimental confirmation of the long coherence time of the meta-stable 62D5/2 state is important in light of the possibility of using a single trapped radium ion as an optical frequency standard.

Atomic parity violation (APV) can be measured in a single Ra+ ion, enabling a precise measurement of the electroweak mixing angle in the Standard Model of particle physics at low momentum transfer. This provides sensitivity to new particles such as extra Z0 bosons or leptoquarks. The Weinberg angle can be measured via a determination of the light shift in the forbidden 72S1/2–62D3/2 transition in a single trapped Ra+. Ultra-narrow transitions in such an ideal system can also be exploited to realize a high stability frequency standard. At the TRIμP facility of KVI, we have succeeded in the production of a series of radioactive short-lived radium isotopes. The radium isotopes produced were stopped and thermalized to Ra+ in a thermal ionizer, mass separated in a Wien filter, cooled in a gas filled radio frequency quadrupole and subsequently trapped as a cloud in a linear Paul trap. Laser spectroscopy in the trapped radium ions has been performed. The results of hyperfine structure, isotope shift, and lifetime measurements are important experimental inputs to test the accuracy of atomic theory, the precision of which is indispensable for extracting the Weinberg angle. These results are also of relevance for a possible atomic clock, based on trapped Ra+.

Modern experiments on neutron and allowed nuclear $\beta$ decay search for new semileptonic interactions, beyond the ``left-handed'' electroweak force. We show that ongoing and planned $\beta$-decay experiments, with isotopes at rest and in flight, can be exploited as sensitive tests of Lorentz invariance. The variety of correlations that involve the nuclear spin, the direction of the emitted $\beta$ particle, and the recoil direction of the daughter nucleus allow for relatively simple experiments that give direct bounds on Lorentz violation. The pertinent observables are decay-rate asymmetries and their dependence on sidereal time. We discuss the potential of several asymmetries that together cover a large part of the parameter space for Lorentz violation in the gauge sector. High counting statistics is required., Comment: Accepted for publication as a Rapid communication in Phys. Rev. C

Searches for Lorentz violation were recently extended to the weak sector, in particular neutron and nuclear $\beta$ decay [1]. From experiments on forbidden $\beta$-decay transitions strong limits in the range of $10^{-6}$-$10^{-8}$ were obtained on Lorentz-violating components of the $W$-boson propagator [2]. In order to improve on these limits strong sources have to be considered. In this Brief Report we study isotopes that undergo orbital electron capture and allow experiments at high decay rates and low dose. We derive the expressions for the Lorentz-violating differential decay rate and discuss the options for competitive experiments and their required precision., Comment: accepted for publication as a Brief Report in Physical Review C

We investigate parity and time-reversal violation in neutron-proton scattering in the optical regime. We calculate the neutron spin rotation and analyzing power in scattering on polarized protons. This allows us to quantify the sensitivity that such experiments should aim for in order to be competitive to present-day measurements of the neutron electric dipole moment in constraining the P- and T-odd two-nucleon interaction. While state-of-the-art techniques fall short by some three orders of magnitude for the neutron-proton case, specific neutron-nucleus experiments look promising, provided certain experimental and theoretical challenges are met.

At the Kernfysisch Versneller Instituut a new facility (TRImuP) is under development which aims, to investigate fundamental interactions using radioactive ions. A spectrum of radioactive isotopes will be produced in inverse-kinematics and fragmentation reactions using heavy-ion beams from the superconducting cyclotron AGOR. The reaction products will be separated from the primary beam in a dual-mode recoil and fragment separator. The beam of isotopes of interest will be transformed into a low-energy, high-quality, bunched beam and, after neutralization, stored in an atom trap. The emphasis will be put on studying the origin of parity violation via beta-v angular correlations and the search for permanent electric dipole moments of atoms and nuclei. The facility will be open to outside users; suggestions for collaborations to extend the scientific program are encouraged. (C) 2003 Elsevier Science B.V. All rights reserved.

After reviewing the method of energy-dependent partial-wave analysis of the two-nucleon scattering data, I report on recent work to include the two-pion-exchange interaction [1,2]. The chiral two-pion-exchange component of the long-range nucleon-nucleon interaction is derived from the effective chiral Lagrangian. Its presence and importance is demonstrated in the partial-wave analysis. The values of the chiral coupling constants c(i) (i = 1,3,4) are determined in a fit to the data, and agree well with those obtained previously from pion-nucleon scattering amplitudes.

Photons originating from coherent bremsstrahlung have been measured over a large dynamic range for the reaction of 200 MeV alpha particles with protons. At low photon energies the bremsstrahlung spectrum exhibits the classical behavior with an approximate 1/E-gamma shape. At higher photon energies there is a pronounced contribution from capture into the unbound ground state and first excited state of Li-5. These results allow one, for the first time, to test theoretical models for a consistent description of bremsstrahlung and radiative capture in a complex system. Calculations predict both features qualitatively but fail to account for their relative importance.

The proton-proton bremsstrahlung process, including both coplanar and non-coplanar kinematics, has been measured with polarized protons of 190 MeV. High-precision cross sections and analyzing powers have been obtained. Cross sections as a function of non-coplanarity angle are presented and show large variations of dynamical origin. Non-coplanar analyzing powers have been measured for the first time and are compared to theoretical predictions. (C) 2000 Elsevier Science B.V. All rights reserved.

An exclusive proton-proton bremsstrahlung measurement has been performed with polarized protons of 190 MeV. Absolute cross sections and analyzing powers have been measured with unprecedented accuracy in a large part of the phase space. The data are compared with state-of-the-art theoretical calculations including higher-order off-shell effects, like the Delta isobar and meson-exchange currents. Surprisingly, the calculations are unable xo describe the data in detail.

The chiral two-pion exchange component of the long-range pp interaction is studied in an energy-dependent partial-wave analysis. We demonstrate its presence and importance, and determine the chiral parameters c_i (i=1,3,4). The values agree well with those obtained from pion-nucleon amplitudes., 13 pages, no figures

We re-examine the puzzling π + emission from the weak decay of Λ 4 He and propose an explanation in terms of a three-body decay of the virtual Σ + . Such a resolution of the π + decay puzzle is consistent with the calculated Σ + probability in light Λ hypernuclei as well as the experimentally observed π + energy spectrum and s -wave angular distribution.

The situation in low-energy pion-nucleon scattering is reviewed, using an energy-dependent PWA as a tool. The method and some conclusions of this new PWA of πN scattering data across the Δ(1232) are summarized. In particular, the “inconsistencies” in the low-energy database are addressed, and the state-of-the-art of the NNπ coupling constant and of the πN σ-term is discussed.

We consider the possibility of Lorentz-invariance violation in weak-decay processes. We present a general approach that entails modifying the W-boson propagator by adding a Lorentz-violating tensor to it. We describe the effects of Lorentz violation on nuclear beta decay in this scenario. In particular we show the expression for a first-forbidden transition with a spin change of two. Using data from an old experiment on the rotational invariance of yttrium-90, we derive several bounds on the Lorentz-violating parameters of the order of 10^(-6)-10^(-8).

The KLOE collaboration recently reported bounds on the directional dependence of the lifetime of the short-lived neutral kaon K_S with respect to the cosmic microwave background dipole anisotropy. We interpret their results in a general framework developed to probe Lorentz violation in the weak interaction. In this approach a Lorentz-violating tensor \chi_{\mu\nu} is added to the standard propagator of the W boson. We derive the K_S decay rate in a naive tree-level model and calculate the asymmetry for the lifetime. By using the KLOE data the real vector part of \chi_{\mu\nu} is found to be smaller than 10^-2. We briefly discuss the theoretical challenges concerning nonleptonic decays.

The KLOE collaboration recently reported bounds on the directional dependence of the lifetime of the short-lived neutral kaon $K^0_S$ with respect to the dipole anisotropy of the cosmic microwave background. We interpret their results in an effective field theory framework developed to probe the violation of Lorentz invariance in the weak interaction and previously applied to semileptonic processes, in particular $\beta$ decay. In this approach a general Lorentz-violating tensor $\chi^{\mu\nu}$ is added to the standard propagator of the $W$ boson. We perform an exploratory study of the prospects to search for Lorentz violation in nonleptonic decays. For the kaon, we find that the sensitivity to Lorentz violation is limited by the velocity of the kaons and by the extent to which hadronic effects can be calculated. In a simple model we derive the $K^0_S$ decay rate and calculate the asymmetry for the lifetime. Using the KLOE data, limits on the values of $\chi^{\mu\nu}$ are determined., Comment: accepted for publication in Physics Letters B

A new test of Lorentz invariance in the weak interactions has been made by searching for variations in the decay rate of spin-polarized 20Na nuclei. This test is unique to Gamow-Teller transitions, as was shown in the framework of a recently developed theory that assumes a Lorentz symmetry breaking background field of tensor nature. The nuclear spins were polarized in the up and down direction, putting a limit on the amplitude of sidereal variations of the form |(\Gamma_{up} - \Gamma_{down})| / (\Gamma_{up} + \Gamma_{down}) < 3 * 10^{-3}. This measurement shows a possible route toward a more detailed testing of Lorentz symmetry in weak interactions., Comment: 11 pages, 6 figures

We study charmed and strange odd-parity baryon resonances that are generated dynamically by a unitary baryon-meson coupled-channels model which incorporates heavy-quark spin symmetry. This is accomplished by extending the SU(3) Weinberg-Tomozawa chiral Lagrangian to SU(8) spin-flavor symmetry plus a suitable symmetry breaking. The model generates resonances with negative parity from the s-wave interaction of pseudoscalar and vector mesons with 1/2(+) and 3/2(+) baryons in all the isospin, spin, and strange sectors with one, two, and three charm units. Some of our results can be identified with experimental data from several facilities, such as the CLEO, Belle, or BaBar Collaborations, as well as with other theoretical models, whereas others do not have a straightforward identification and require the compilation of more data and also a refinement of the model., This research was supported by DGI and FEDER funds, under contracts FIS2011-28853-C02-02, FIS2011-24149, FPA2010-16963 and the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042), by Junta de Andalucia grant FQM-225, by Generalitat Valenciana under contract PROMETEO/2009/0090 and by the EU HadronPhysics2 project, grant agreement No. 227431. O.R. wishes to acknowledge support from the Rosalind Franklin Fellowship. L.T. acknowledges support from Ramon y Cajal Research Programme, and from FP7-PEOPLE-2011-CIG under contract PCIG09-GA-2011-291679.

Forbidden (slow) beta decays offer new opportunities to test the invariance of the weak interaction under Lorentz transformations. Within a general effective field theory framework we analyze and reinterpret the only two relevant experiments, performed in the 1970s, dedicated to search for a preferred direction in space in first- and second-forbidden beta decays. We show that the results of these experiments put strong and unique limits on Lorentz violation, and in particular on the presence of several interactions in the modern Lorentz-violating Standard Model extension. We discuss prospects to improve on these limits., 10 pages

Background: The search for violations of Lorentz invariance is nowadays motivated by attempts to unify the standard model of particle physics with general relativity. Such theories of ``quantum gravity'' predict Lorentz-violating signals that could be detected in low-energy precision experiments. In this context, Lorentz invariance has been tested poorly in the weak interaction.Purpose: We explore the possibility that the weak interaction violates Lorentz, and in particular rotational, invariance in neutron and allowed nuclear $\ensuremath{\beta}$ decay.Method: A broad class of Lorentz-violating effects is considered in an effective field theory approach, wherein the standard propagator of the $W$ boson acquires an additional Lorentz-violating tensor.Results: The general decay rate for allowed $\ensuremath{\beta}$ decay that incorporates the modified $W$-boson propagator is derived. The resulting Lorentz-violating signals are discussed for the different types of $\ensuremath{\beta}$-decay transitions: Fermi, Gamow-Teller, and mixed. We study the implications of our formalism for dedicated $\ensuremath{\beta}$-decay experiments. We give a short overview of the few relevant experiments that have been performed in the past or are ongoing.Conclusions: Our work provides a general theoretical framework that should be used for designing and interpreting $\ensuremath{\beta}$-decay experiments that search for Lorentz violation. In particular, it determines the kind of experiments that are necessary to probe different parameters that quantify Lorentz violation, and it establishes their sensitivity.

Several topics in pion-nucleon scattering at low energies are addressed. First, we review the predictions of chiral symmetry for the near-threshold region. The pion-nucleon scattering lengths and the Cheng-Dashen theorem with the related issue of the strangeness content of the nucleon are discussed in some detail. Finally, the status of the scalar mesons and the relevance of the pomeron and the concept of duality for pion-nucleon dynamics is pointed out.

We calculate the toroidal quadrupole moment and form factor of the deuteron, which violate time-reversal symmetry but conserve parity, at leading order in two-flavor chiral effective field theory with perturbative pion exchange. We take into account time-reversal and parity violation owing to the QCD vacuum angle combined with parity violation resulting from the weak interaction in the Standard Model. We also consider time-reversal and parity violation that at the quark-gluon level results from effective dimension-six operators originating from physics beyond the Standard Model.

We investigate the polarization parameters in low-energy antiproton-proton elastic ((p) over barp -> (p) over barp) and charge-exchange ((p) over barp -> (n) over barn) scattering. The predictions for unmeasured observables are based on our new energy-dependent partial-wave analysis of all antiproton-proton scattering data below 925 MeV/c antiproton laboratory momentum, which gives an optimal description of the existing database. Sizable and remarkable spin effects are observed, in particular for charge-exchange scattering. These result from the spin dependence of the long- and medium-range one- and two-pion exchange antinucleon-nucleon potential and the state dependence of the parametrized short-range interaction. We study the possibility of polarizing a circulating antiproton beam with a polarized proton target by exploiting the spin dependence of the (p) over barp total cross section. It appears feasible to achieve a significant transverse polarization of an antiproton beam within a reasonable time.

At the Kernfysisch Versneller Instituut (KVI) a new facility (TRIμP) is under development. It aims for producing a spectrum of radioactive isotopes in direct, inverse kiematics fusion and evaporation or fragmentation reactions with heavy ion beams from the superconducting cyclotron AGOR. The products will be slowed down and trapped for accurate measurements of fundamental symmetries and interactions in physics. The scientific focus of the local KVI research groups includes precision studies of nuclear β-decays through β-neutrino (recoil nucleus) momentum correlations in weak decays and searches for permanent electric dipole moments in heavy atomic systems. This research programme offers a large potential for discovering new physics or to limit parameters in models beyond standard theory significantly. The scientific approach chosen in TRIμP can be regarded as complementary to such high energy physics. The TRIμP facility in Groningen will be open for users worldwide.

Background: There is a renewed experimental interest in antiproton-proton scattering with an intense, possibly polarized antiproton beam. On the theoretical side, significant progress has been made in the understanding of the nuclear force from chiral effective field theory.Purpose: We provide a high-quality model-independent description of the available low-energy antiproton-proton scattering data. Method: We perform a new energy-dependent partial-wave analysis of all antiproton-proton elastic ((p) over barp -> (p) over barp) and charge-exchange ((p) over barp -> (n) over barn) scattering data below 925 MeV/c antiproton laboratory momentum. The Schrodinger equation is solved for the coupled (p) over barp and (n) over barn channels. The relevant long-range parts of the electromagnetic and the one-and two-pion exchange interactions are included exactly. The short-range interactions, including the coupling to the mesonic annihilation channels, are parametrized by a complex boundary condition at a radius of r = 1.2 fm.Results: The updated database, which includes significantly more high-quality charge-exchange data, contains 3749 scattering data. The fit gives chi(2)(min)/N-df = 1.048, where N-df = 3578 is the number of degrees of freedom. We discuss the description of the experimental data and we present the antiproton-proton phase-shift parameters.Conclusions: Chiral effective field theory provides an excellent long-range antinucleon-nucleon interaction. The results of the PWA should serve as the starting point for future theoretical and experimental investigations of low-energy antiproton-proton scattering.

We present a combined analysis of the available isotope-shift data from the optical spectra of Ra atoms and Ra${}^{+}$ ions. Atomic structure calculations of the field-shift and specific mass-shift constants of the low-lying levels in Ra${}^{+}$ are used. The nuclear radial differences $\ensuremath{\delta}\ensuremath{\langle}{r}^{2}\ensuremath{\rangle}$ for the radium isotopes are derived and compared to previous analyses and nuclear models. We discuss the relevance of our results to measurements of atomic parity violation in a chain of Ra${}^{+}$ isotopes.

We calculate the magnetic quadrupole moment (MQM) of the deuteron at leading order in the systematic expansion provided by chiral effective field theory. We take into account parity (P) and time-reversal (T) violation which, at the quark-gluon level, results from the QCD vacuum angle and dimension-six operators that originate from physics beyond the Standard Model. We show that the deuteron MQM can be expressed in terms of five low-energy constants that appear in the P- and T-violating nuclear potential and electromagnetic current, four of which also contribute to the electric dipole moments of light nuclei. We conclude that the deuteron MQM has an enhanced sensitivity to the QCD vacuum angle and that its measurement would be complementary to the proposed measurements of light-nuclear EDMs. (C) 2012 Elsevier B.V. All rights reserved.

We set up the framework for the calculation of electric dipole moments (EDMs) of light nuclei using the systematic expansion provided by chiral effective field theory (EFT). We take into account parity (P) and timer-reversal (T) violation which, at the quark-gluon level, originates from the QCD vacuum angle and dimension-six operators capturing physics beyond the standard model. We argue that EDMs of light nuclei can be expressed in terms of six low-energy constants that appear in the P- and T-violating nuclear potential and electric current. As examples, we calculate the EDMs of the deuteron, the triton, and (3)He in leading order in the EFT expansion.

Laser spectroscopy of short-lived radium isotopes in a linear Paul trap has been performed. The isotope shifts of the $6d\phantom{\rule{0.16em}{0ex}}{{}^{2}\phantom{\rule{-0.16em}{0ex}}D}_{3/2}\phantom{\rule{0.16em}{0ex}}$--$7\phantom{\rule{-0.16em}{0ex}}p\phantom{\rule{0.16em}{0ex}}{{}^{2}\phantom{\rule{-0.16em}{0ex}}P}_{1/2}\phantom{\rule{0.16em}{0ex}}$ transition in ${}^{209\ensuremath{-}214}$Ra${}^{+}$, which are sensitive to the short-range part of the atomic wave functions, were measured. The results are essential experimental input for improving the precision of atomic structure calculations. This is indispensable for parity violation in Ra${}^{+}$ aiming at the determination of the weak mixing angle.

We calculate the electric-dipole and magnetic-quadrupole form factors of the deuteron that arise as a low-energy manifestation of parity and time-reversal violation in quark-gluon interactions. We consider the QCD vacuum angle and the dimension-six operators that originate from physics beyond the standard model: the quark electric and chromoelectric dipole moments and the gluon chromoelectric dipole moment. Within the framework of two-flavor chiral perturbation theory, we show that in combination with the nucleon electric dipole moment, the deuteron moments would allow an identification of the dominant source(s) of symmetry violation.

We explore the potential of the electric quadrupole transitions 7s {sup 2}S{sub 1/2}-6d {sup 2}D{sub 3/2}, 6d {sup 2}D{sub 5/2} in radium isotopes as single-ion optical frequency standards. The frequency shifts of the clock transitions due to external fields and the corresponding uncertainties are calculated. Several competitive {sup A}Ra{sup +} candidates, with A= 223-229, are identified. In particular, we show that the transition 7s {sup 2}S{sub 1/2} (F=2,m{sub F}=0)-6d {sup 2}D{sub 3/2} (F=0,m{sub F}=0) at 828 nm in {sup 223}Ra{sup +}, with no linear Zeeman and electric quadrupole shifts, stands out as a relatively simple case, which could be exploited as a compact, robust, and low-cost atomic clock operating at a fractional frequency uncertainty of 10{sup -17}. With more experimental effort, the {sup 223,225,226}Ra{sup +} clocks could be pushed to a projected performance reaching the 10{sup -18} level.

As an important step toward an atomic parity violation experiment in one single trapped Ra${}^{+}$ ion, laser spectroscopy on short-lived $^{212,213,214}\mathrm{Ra}$${}^{+}$ ions was conducted. The isotope shift of the $6 {}^{2}{D}_{3/2}$-$7 {}^{2}{P}_{1/2} $and $6 {}^{2}{D}_{3/2}$-$7 {}^{2}{P}_{3/2} $transitions and the hyperfine structure constants of the $7 {}^{2}{P}_{1/2} $and $6 {}^{2}{D}_{3/2} $states in $^{213}\mathrm{Ra}$${}^{+}$ were measured, which provides a benchmark for the required atomic theory. A lower limit of $232(4)$ ms for $6 {}^{2}{D}_{5/2} $state lifetime was determined.

We calculate the electric dipole form factor of the nucleon that arises as a low-energy manifestation of time-reversal violation in quark-gluon interactions of effective dimension 6: the quark electric and chromoelectric dipole moments, and the gluon chromoelectric dipole moment. We use the framework of two-flavor chiral perturbation theory to one loop. (C) 2010 Elsevier B.V. All rights reserved.

Static dipole polarizabilities are calculated in the ground and metastable states of Sr{sup +}, Ba{sup +} and Ra{sup +} using the relativistic coupled-cluster method. Trends of the electron correlation effects are investigated in these atomic ions. We also estimate the Stark and black-body radiation shifts from these results for these systems for the transitions proposed for the optical frequency standards and compare them with available experimental data.

We present an analysis of the recent measurements of the light-shift ratio in ${\text{Ba}}^{+}$ at two different wavelengths that enables us to reduce the uncertainty of the largest $E1$ dipole matrix elements of ${\text{Ba}}^{+}$. These matrix elements are, for instance, of interest for the proposed parity-nonconservation (PNC) experiment in ${\text{Ba}}^{+}$. We show that a new measurement of the light-shift ratio in ${\text{Ba}}^{+}$ at a wavelength of 350 nm could further reduce the uncertainty of the (for PNC studies most important) $⟨5{D}_{3/2}||D||6{P}_{1/2}⟩$ matrix element. Finally, as groundwork for the planned PNC experiment at KVI, we present relativistic coupled-cluster calculations of the $E1$ matrix elements for ${\text{Ra}}^{+}$, and investigate the potential of similar light-shift ratio measurements in this ion.