The European Physical Journal D最新文献

We present a systematic study of the nucleon-electron tensor-pseudotensor (Ne-TPT) interaction in the francium-silver (FrAg), cesium-silver (CsAg), and francium-lithium (FrLi) molecules which are candidates for next-generation experimental searches for new sources of charge-parity violation. The considered molecules are all amenable to assembly from laser-cooled atoms, with the FrAg molecule previously shown to be the most sensitive to the Schiff moment interaction in this set. Interelectron correlation effects are treated through relativistic general-excitation-rank configuration interaction theory in the framework of the Dirac–Coulomb Hamiltonian. We find in FrAg the Ne-TPT interaction constant to be (W_T({text {Fr}}) = 2.57 pm 0.21 [left<Sigma right>_A textrm{kHz}]), considering the Francium atom as target of the measurement. Taking into account nuclear structure in a multi-source interpretation of a measured electric dipole moment, FrAg is found to be an excellent probe of physics beyond the standard model as this system will in addition to its sizeable Ne-TPT interaction constant greatly constrain fundamental parameters such as the semileptonic four-fermion interaction (C_{text {lequ}}) from which nuclear and atomic (mathcal{{CP}})-violating properties arise.

Nucleon–electron tensorpseudotensor interaction on the Francium target nucleus in the Francium-Silver molecule, where the corresponding Hamiltonian operator is parity- and time-reversal violating. Details of the interaction are explained in the paper body. These interactions give rise to molecular charge-parity violating effects that can be detected by experiments.

Experimental dielectronic recombination spectra of highly charged ions, measured at the storage ring using the electron-ion merged-beam technique, are known for their high resolutions at low collision energies. This resolutions is quite in contrast to the present computations of the low-lying resonances and plasma rate coefficients, which are still a challenge for modern atomic theory. In this study, we investigate the dielectronic and tri-electronic recombination strengths of low-lying resonances for beryllium-like argon ions in the low energy range (0–5 eV) by using the newly developed Jena Atomic Calculator (JAC). JAC is a relativistic computational code based on the multi-configuration Dirac–Hartree–Fock (MCDHF) method. Our calculated strengths are compared with both experimental data and recent theoretical calculations by Zhang et al. (Phys Rev A 108:022801, 2023), showing good agreement within experimental uncertainties. Furthermore, in combination with a dielectronic cascade model, we derive the plasma rate coefficients for the (Delta n = 0) transition over a wide temperature range from (10^3) K to (10^7) K. These rapidly derived, reliable plasma rate coefficients have potential applications in astrophysics and plasma physics.

The potential of circulating antideuterons ((mathrm {overline{d}})) in the AD/ELENA facility at CERN is under active investigation. Approximately 100 (mathrm {overline{d}}) per bunch could be delivered as a ({100,textrm{keV}}) beam based on measured cross-sections. These (mathrm {overline{d}}) could be further decelerated to ({12,textrm{keV}}) using the GBAR scheme, enabling the synthesis of antideuterium ((mathrm {overline{D}})) via charge exchange with positronium, a technique successfully demonstrated with ({6,textrm{keV}}) antiprotons for antihydrogen production. The AD/ELENA facility is currently studying the possibility of increasing the (mathrm {overline{d}}) rate using an optimized new target geometry. Assuming this is feasible, we propose further enhancing the anti-atom production by using laser-excited positronium in the 2P state within a cavity, which is expected to increase the (mathrm {overline{D}}(2S)) production cross-section by almost an order of magnitude for (mathrm {overline{d}}) with ({2,textrm{keV}}) energy. We present the projected precision for measuring the antideuterium Lamb shift and extracting the antideuteron charge radius, as a function of the beam flux.

(mathrm {overline{D}}) production rate assuming 1e9 ortho-(textrm{Ps}) from a flat target interact with (mathrm {overline{d}}) with ({12,mathrm{text {k}text {eV}}}) (blue) or inside a cavity (orange). Within the cavity, (textrm{Ps}) can be excited to the 2P state, further increasing the charge exchange cross-section for (mathrm {overline{d}}) at ({2,mathrm{text {k}text {eV}}}) (green). Cross-sections are calculated using the Convergent Close Coupling (CCC, solid) method [36] and the Coulomb-Born approximation (CBA, dashed) [37]

Positronium and muonium, as purely leptonic atoms without internal structure, provide ideal systems for high-precision tests of quantum electrodynamics (QED) and measurements of fundamental constants. However, the high velocities of these lightweight atoms complicate precision spectroscopy, particularly in the 1 S-2 S transition, due to transit time broadening and second-order Doppler shifts. To overcome these challenges, we propose a novel method combining two-photon Ramsey spectroscopy with a technique to correct the second-order Doppler shifts on an atom-by-atom basis. Additionally, this approach suppresses systematic effects of the AC Stark shift to a negligible level compared to the target precision. Simulations predict that for both positronium and muonium, this method could improve the measurement precision of the 1 S-2 S transition by more than two orders of magnitude compared to the current state of the art. This approach opens up new avenues for rigorous bound state QED tests and searches for physics beyond the standard model.

Dianionic tin clusters (textrm{Sn}_{34}^{2-}) stored in a Penning trap are excited by nanosecond laser pulses with photon energies ranging from 2.0 to (4.7,textrm{eV}), resulting in delayed decays. Time-resolved measurements with varying delays between laser irradiation and fragment analysis from a few ten microseconds to a second reveal matching exponential appearance constants of several singly charged dissociation products. This indicates that the dianions undergo fission into competing pairs of (textrm{Sn}_{10}^{-}) + (textrm{Sn}_{24}^{-}) and (textrm{Sn}_{15}^{-}) + (textrm{Sn}_{19}^{-}). Furthermore, matching decay constants for high photon energies of twice the low-energy values indicate that the decay observed at the low energies results from two-photon excitation.The delayed photodecay of dianionic tin clusters shows competing dissociation pathways by fission into two singly charged product clusters. Further sequential decay processes are investigated.

Methods of angular momenta are modified and used to solve some actual problems in quantum mechanics. In particular, we re-derive some known formulas for analytical and numerical calculations of matrix elements of the vector physical quantities. These formulas are applied to a large number of quantum systems which have an explicit spherical symmetry. Multiple commutators of different powers of the angular momenta ({hat{textbf{J}}}^{2}) and vector-operator ({hat{textbf{A}}}) are determined in the general form. Calculations of the expectation values averaged over orbital angular momenta are also described in detail. This effective and elegant old technique, which was successfully used by Enrico Fermi and Aage Bohr, is almost forgotten in modern times. We also discuss quantum systems with additional relations (or constraints) between some vector-operators and orbital angular momentum. For similar systems such relations allow one to obtain some valuable additional information about their properties, including the bound state spectra, correct asymptotics of actual wave functions, etc. As an example of unsolved problems we consider applications of the algebras of angular momenta to investigation of the one-electron, two-center (Coulomb) problem ((Q_1, Q_2)). For this problem it is possible to obtain the closed analytical solutions which are written as the ‘correct’ linear combinations of products of the two one-electron wave functions of the hydrogen-like ions with the nuclear charges (Q_1 + Q_2) and (Q_1 - Q_2), respectively. However, in contrast with the usual hydrogen-like ions such hydrogenic wave functions must be constructed in three-dimensional pseudo-Euclidean space with the metric ((-1,-1,1)).

Plasma screening effects on the above-threshold ionization (ATI) of the argon atom in Gaussian windowed soft-core Coulomb (GSC) potential is investigated using the time-dependent Schrödinger equation (TDSE), by employing the Crank–Nicolson numerical method. The variation in the ground-state population and ionization probabilities with time is calculated in the Debye plasma environment. The effect of laser intensity variations on the ATI spectra of argon atom is calculated, and ATI spectra show a similar pattern of redshift, as discussed in the available literature. Plasma screening effects on the population of ground state, ionization probabilities, and ATI spectra of argon atom are studied in GSC potential for the first time, at different laser intensities and Debye lengths.

A tripartite state is said to be a potential resource for secret sharing if in addition to being useful for the secret reconstruction (Singh and Chakrabarty in: Phys Rev A 109(3):032406, 2024), it imposes restrictions on the teleportation fidelity of the bipartite channels associated with three-qubit states (dealer–reconstructor and dealer–assistant channels). It is important to ask the question: for a given class of states satisfying some constraint, which secret sharing resources will have the maximum possible reconstruction fidelity? Here, we address this question for a pure three-qubit GHZ class of states (sometimes referred as Acin states) (Antonio Acín et al. in: J Phys A Math Gen 34(35):6725, 2001; Acín et al. in: Phys Rev Lett 87(4):040401, 2001). We are able to characterize the set of states with maximum possible reconstruction fidelity (called as maximal secret reconstructible state [MSR]). Here, the constraint in characterizing the states is a fixed value of the maximum of the teleportation fidelity of both the bipartite (dealer–receivers) channels. In that spirit our result paves the way in setting the practical information transfer limit in a possible resource theoretic extension of secret sharing. Similarly for a value giving the maximum of Bell-CHSH value of both bipartite channels (dealer–reconstructor and dealer–assistant), we are able to find the maximum achievable reconstruction fidelity. Interestingly, we find that all secret shareable states satisfy Bell’s inequality in both the channels (dealer–reconstructor and dealer–assistant partitions). This brings out a new mutual exclusivity between secret shareable state and Bell’s inequality violation.