Search

This work is part of an ongoing effort to build microscopicallydriven nonlocal optical potentials easily tracktable in scattering codes. Based on the separable 'JνH' structure proposed recently [1], where the potential can be cast as the product of a radial and nonlocality form factors, we investigate its angular dependence in momentum space. We find that scattering observables have a weak angular dependence between the momentum transfer q = k − k′, and K = (k + k′)/2. The study is focussed on proton elastic scattering off 40Ca at 200 MeV, where the JνH structure is found to be inadequate. We conclude that any improvement of the JνH structure of the potential can be made to the lowest order in multipole expansions in Kq−representation of the potential. [ABSTRACT FROM AUTHOR]

The Standard Model (SM) of Particle Physics cannot explain the matter-antimatter asymmetry in the Universe. Especially, new sources of CP-violation are necessary, and this is why physics beyond the SM is being explored. The search for permanent Electric Dipole Moments (EDMs) of elementary particles has the potential to provide a powerful tool to discover new sources of CP-violation. Finding an EDM would be a convincing indication for physics beyond the SM. Moreover, a rotating polarized beam used in EDM searches is sensitive to oscillating EDM caused by axions or axion-like particles (ALPs), the candidates for the dark matter. Storage rings are promising devices to measure EDMs of charged particles by observing the effect of the EDM on the spin motion in the ring. The Cooler Synchrotron COSY at the Forschungszentrum Jülich provides polarized protons and deuterons with momenta up to 3.7 GeV/c and it constitutes an suitable testing ground and starting point for an experimental program to search for EDMs of charged particles. This report provides an overview of the current status of the JEDI project for the first direct measurement of the deuteron EDM at COSY. The analysis is currently ongoing. Due to the complexity of storage rings, this study combines high precision measurements and thorough understanding of the systematic uncertainties involved. [ABSTRACT FROM AUTHOR]

At the Paul Scherrer Institute (PSI) we are developing a high precision instrument to measure the muon electric dipole moment (EDM). The experiment is based on the frozen-spin method in which the spin precession induced by the anomalous magnetic moment is suppressed, thus increasing the signal-to-noise ratio for EDM signals to achieve a sensitivity otherwise unattainable using conventional g - 2 muon storage rings. The expected statistical sensitivity for the EDM after a year of data taking is 6 10−23e cm with the p = 125 MeV/c muon beam available at the PSI. Reaching this goal necessitates a comprehensive analysis on spurious effects that mimic the EDM signal. This work discusses a quantitative approach to study systematic effects for the frozen-spin method when searching for the muon EDM. Equations for the motion of the muon spin in the electromagnetic fields of the experimental system are analytically derived and validated by simulation. [ABSTRACT FROM AUTHOR]

The 13th International Conference on Hypernuclear and Strange Particle Physics (HYP2018) is summarized based on plenary talks given in the conference. It covers recent results and future prospects of theoretical and experimental studies on baryon-baryon interactions, hypernuclei, strangeness production, hadrons and nuclei with heavy flavors, and related subjects. [ABSTRACT FROM AUTHOR]

Charge symmetry is broken in Quantum Chromodynamics (QCD) by the up-down quark mass difference and electromagnetic interactions. In Λ hypernuclei, charge symmetry breaking (CSB) manifests itself in the charge dependence of Λ binding energies, BΛ. The full understanding of the sign, the size, and the spin-dependence of the CSB effect for isospin multiplets of different mass numbers remains one of the unresolved issues of hypernuclear physics. Experimentally, the only sizable CSB effect in hypernuclei was found in the A = 4 isospin mirror pair, making it exceptional among the hypernuclei. A renewed statistical analysis of six published BΛ values for 4ΛH is presented, adopting the Particle Data Group (PDG) procedures for error treatments including correlations. Its binding energy was estimated to be B̄Λ= 2:095 ± 0:043 MeV. The world database of hypernuclear binding energies, in particular for the A = 4 system and the problematic 12ΛC case, is critically reviewed. Obviously, precise binding and excitation energy data represent the fundamental building blocks to study CSB and many other aspects of hypernuclear physics. [ABSTRACT FROM AUTHOR]

Several persistent problems in strangeness nuclear physics are discussed in this opening talk at HYP2018, Norfolk VA, June 2018: (i) the ³ΛH, and ³Λn if existing, lifetimes; (ii) charge symmetry breaking in Λ hypernuclei; (iii) the overbinding of 5ΛHe which might be related to the hyperon puzzle in neutron stars; and (iv) does Λ ∗(1405) survive in strange hadronic matter? [ABSTRACT FROM AUTHOR]

We have investigated the Gamow-Teller transitions from 10Be(0+ 1 1) →10B(1+0) and 22Ne(0+ 1 1) → 22Na(1+0) by using the isospin projected antisymmetrized molecular dynamics combined with the generator coordinate method (T βγ-AMD+GCM). We have found that the fragmentation of GT strength in 22Ne(0+ 1 1) → 22Na(1+0) can be explained by introducing K-bands originated from a S = 1 proton-neutron (pn) pair in the prolately deformed 20Ne core. The SU(4)-symmetry breaking of the pn pair into S z = 0 and S z = ±1 plays an important role in this GT fragmentation. We have discussed the link of the SU(4)-symmetry and the GT fragmentation in the deformed systems by artificially changing the spin-orbit interaction on the GCM calculation. [ABSTRACT FROM AUTHOR]

AMS applications with lighter nuclei are presented. It will be shown how Carbon-14, Boron-10, Beryllium-10, and Tritium-3 can be used to provide valuable information in forensic science, environmental physics, nuclear pollution, in material science and for diagnose of the plasma confinement in fusion reactors. Small accelerators are reliable, efficient and possess the highest ion beam transmissions that confer high precision in measurements. [ABSTRACT FROM AUTHOR]

Charge symmetry breaking in the A = 4 hypernuclear system is reviewed. The data on binding energies of the mirror nuclei and hypernuclei are examined. At the Mainz Microtron MAMI the high-resolution spectroscopy of decay-pions in strangeness electro-production is used to extract the Λ hyperon ground state binding energy in 4ΛH. This binding energy is used together with the 4ΛHe ground state binding energy from nuclear emulsion experiments and with energy levels of the 1+ excited state for both hypernuclei from γ-ray spectroscopy to address the charge symmetry breaking in the strong interaction. The binding energy difference of the ground states in the mirror pair is reduced from its long accepted value ΔB4Λ(0+g.s.) ≈ 0.35MeV to ≈ 0.24MeV. The energy difference of the excited states becomes ΔB4Λ(1+exc) ≈ −0.08MeV, for the first time with opposite sign. These values were not reproduced by theoretical calculations with the exception of very recent approaches, although with a large systematic dependence. The full understanding of the charge symmetry breaking in the A = 4 hypernuclei still remains one of the open issues of hypernuclear physics. [ABSTRACT FROM AUTHOR]

We discuss a recent global calculation of beta-decay rates in the self-consistent Skyrme quasiparticle random phase approximation (QRPA), with axially symmetric nuclear deformation treated explicitly. The calculation makes makes use of the finite-amplitude method, first proposed by Nakatsukasa and collaborators, to reduce computation time. The results are comparable in quality to those of several other global QRPA calculations. The QRPA may have reached the limit of its accuracy. [ABSTRACT FROM AUTHOR]

Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In order to provide still missing data the physics program of WASA-at-COSY comprises two reaction channels. An exclusive measurement of the dd → ³Hen π0 reaction was carried out to obtain precise data on the total cross section as well as on the differential distributions. In addition, the studies on the reaction dd → 4He π0 have been extended towards higher excess energies in order to provide information on the contribution of higher partial waves in the final state. [ABSTRACT FROM AUTHOR]

I review the effects of charge symmetry breaking CSB on electromagnetic form factors and how that influences extraction of information regarding nucleon strangeness content and the weak mixing angle. It seems that CSB effects are very modest and should not impact the analysis of experiments. [ABSTRACT FROM AUTHOR]

Tetra-quark mesons with exotic quantum numbers and their production rates are studied. [ABSTRACT FROM AUTHOR]

COSY, a storage and cooler synchrotron, which is fed by an injector cyclotron, is operated at Forschungszentrum Jülich (Germany). It provides phase space cooled polarized or unpolarized beams of protons and deuterons with momenta between 0.3 and 3.7 GeV/c for internal experiments and to external target stations. The major experimental facilities, used for the ongoing physics program, are ANKE and WASA (internal) and TOF (external). A new internal target station to investigate polarization build-up by spin-filtering (PAX) has recently been commissioned. COSY is the machine for hadron spin physics on a world-wide scale, which is also used for tests in conjunction with plans to build a dedicated storage ring for electric dipole moment (EDM) measurements of proton, deuteron and 3He. In this contribution recent results as well as future plans are summarized. [ABSTRACT FROM AUTHOR]

We report on the recent developments of chiral effective field theory for nuclear physics based on Weinberg's power counting. Continuum calculations for deuteron photodisintegration, pion production in neutron-proton fusion and baryon-baryon interactions with strangeness S = -3 and S = -4 are discussed. The lattice formulation of the nuclear forces offers the possibility to study the nuclear many-problem. First results of this approach and some estimates for future simulations are shown. [ABSTRACT FROM AUTHOR]

We show on two examples, namely a calculation for charge symmetry breaking in pn→dπ0 that allows one to extract the quark mass difference induced part of the proton-neutron mass difference and a high precision calculation for pion-deuteron scattering and its implications for the value of the charged pion-nucleon coupling constant, how QCD tests can be performed from low energy hadronic observables. [ABSTRACT FROM AUTHOR]

Angular correlations arising from particle-particle propagation in nuclear matter are presented. Their account emerges from an exact treatment of the Pauli blocking on intermediate states while retaining the angular structure of the energy denominator. As a result, a correlation form factor appears from the Cauchy principal-value of the particle-particle propagator, while the imaginary part becomes structurally different from those in Lippmann-Schwinger-type equations. In selfconsistent runs these features alter the behavior of the mass operator near the Fermi surface, modifying the saturation properties of infinite nuclear matter. [ABSTRACT FROM AUTHOR]

The Chao matrix formalism allows analytic calculations of a beam’s polarization behavior inside a spin resonance. We recently tested its prediction of polarization oscillations occurring in a stored beam of polarized particles near a spin resonance. Using a 1.85 GeV/c polarized deuteron beam stored in COSY, we swept a new rf solenoid’s frequency rather rapidly through 400 Hz during 100 ms, while varying the distance between the sweep’s end frequency and the central frequency of an rf-induced spin resonance. Our measurements of the deuteron’s polarization for sweeps ending near and inside the resonance agree with the Chao formalism’s predicted oscillations. [ABSTRACT FROM AUTHOR]

Recent progress in our three nucleon force study with three nucleon scattering at intermediate energies (E/A≈100 MeV) is presented, especially focusing on experimental deuteron-proton elastic scattering and breakup reactions at RIKEN. One signature of three nucleon forces is identified in the cross section minimum for deuteron-proton elastic scattering by direct comparison between precision data and state-of-the-art Faddeev calculations based on realistic nucleon-nucleon forces plus 2π-exchange three nucleon forces. However, the polarization observables are not always well described by adding the model three nucleon forces, indicating that components other than a 2π-exchange three nucleon force are required to describe the data. [ABSTRACT FROM AUTHOR]

Following an introduction to the physics motivation for the search for an intrinsic electric dipole moment, the possibility of developing a storage ring search using a polarized deuteron beam is reviewed. Such a search involves continuous monitoring of the deuteron beam polarization during the beam store. Polarimeter concepts for this project are developed. [ABSTRACT FROM AUTHOR]

For few body systems, the treatment of charge symmetry breaking (CSB) that is based on meson-exchange models is being replaced by effective field theories whose CSB originates in the down-up quark mass difference and quark electromagnetic effects. In parallel, two new observations of CSB in π0 production (the fore-aft asymmetry in n+p→d+π0 and the total cross section for d+d→4He+π0) provide applicable data. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Recent results on three-nucleon scattering at intermediate energies (E/A ≈ 100 MeV) are presented. Differences between the experimental data and the Faddeev calculations with high precision nucleon-nucleon forces are identified. For the cross section data of elastic deuteron-proton scattering, the agreement is improved by incorporating 2π-exchange three nucleon forces. However the polarization observables are not always described by the three nucleon forces, indicating that components other than 2π-exchange three nucleon forces are required to describe the data. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Fundamental properties of the scalar resonances a0/f0(980), like their masses, widths and couplings to KK, are poorly known. In particular, precise knowledge of the latter quantity would be of great importance since it can be related to the KK content of these resonances. An experimental program is under way at COSY-Jülich aiming at the extraction of the isospin violating a0/f0 mixing amplitude Λ which is in leading order proportional to the product of the coupling constants of the a0 and f0 to kaons. a0/f0 production is studied in pp, pn and dd interactions, both for the KK and the πη/ππ decays, using the ANKE and WASA spectrometers. The latter will be available for measurements at COSY in 2007. As a first step, isovector KK production has been measured in the reaction pp → dK+K0. The data reveal dominance of the a0+ channel, thus demonstrating the feasibility of scalar meson studies at COSY. Analyses of KK- and Kd-FSI effects yield the corresponding scattering lengths, a(KK)I=1 = -(0.02 ± 0.03) - i(0.61 ± 0.05) fm and |Re a(Kd)|≤1.3 fm, Im a(Kd)≤1.3 fm. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Adiabatic approximations to few-body models of nuclear scattering are described with emphasis on reactions with deuterons and halo nuclei (frozen halo approximation) as projectiles. The different ways the approximation should be implemented in a consistent theory of elastic scattering, stripping and break-up are explained and the conditions for the theory’s validity are briefly discussed. A formalism which links few-body models and the underlying many-body system is outlined and the connection between the adiabatic and CDCC methods is reviewed. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Recent results on three-nucleon scattering, especially focusing on elastic nucleon-deuteron scattering at intermediate energies (E/A ≈ 100 MeV) are reviewed. Differences between the experimental data and the Faddeev calculations with high precision nucleon-nucleon forces are identified. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

This report discusses two recent experiments that have produced new results in charge symmetry breaking, the fore-aft cross section asymmetry in n + p → d + π0 and the observation of the isospin-forbidden d + d → 4He + π0 reaction. These experiments are being analyzed using effective field theory that establishes a connection to the quark-level processes that generate all charge symmetry breaking: the down-up quark mass difference and electromagnetic effects among the quarks. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The status of the theoretical effort to calculate charge-symmetry-breaking pion production reactions will be presented. The main emphasis will be on the dd → απ0 reaction, especially in relation to the recent IUCF experiment. Suggestions for future theoretical and experimental work will be made. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

This contribution covers the absolute calibration to better than 1% of the in-beam proton polarimeters at IUCF. The polarimeters observe p+d elastic scattering from thin CD[sub 2] targets at θ[sub lab](d)=42.6°. The calibration standard was double scattering using a [sup 12]C first target and the focal plane polarimeter of the K600 magnetic spectrometer. This procedure gave the beam polarization and the analyzing powers from both targets. Systematic errors are discussed. [ABSTRACT FROM AUTHOR]

We have measured the normal-component spin-transfer observable K[sub NN'] for ↛p elastic scattering to a precision of ±0.02 at 15 angles in the far-backward region (105° ≤ θ[sub cm] ≤ 172°) at a neutron bombarding energy of 187 MeV. This kinematic regime is of particular interest in that the scattering is mediated predominantly through exchange of a single charged pion, and hence is expected to depend sensitively on the strength of the π±NN coupling constant g[sup 2, sub c], a quantity whose precise value remains highly controversial. This controversy has been heightened by new np absolute cross section data, also taken at back angles, which appear to favor the higher values of g&sup2[sub c] obtained in earlier partial-wave analyses, but disagree with most recent predictions. After reviewing the current situation, I will describe the experimental apparatus used in our measurement and our data acquisition and analysis procedures, paying particular attention to potential sources of systematic error and their effect on the data. Our primary result is that these new values for K[sub NN'], in contrast with the recent cross section data, agree most closely with the predictions of modern NN potential models in which a relatively weak πNN coupling is used. [ABSTRACT FROM AUTHOR]