Pseudoscalar Interaction Research Articles

Generalised hydrogen interactions with CINCO: a window to new physics

We present semi-analytic solutions for atomic transition rates in hydrogenic atoms induced by scalar, pseudoscalar, vector, axial-vector, and tensor interactions. Our results agree with quantum electrodynamics predictions to ~ 0.005 % precision, and further allow us to calculate absorption and emission rates for axions, hidden photons, light scalars or other dark matter candidates for hydrogen and hydrogenic ions. These results can be used to inform searches for light new physics as well as in calculations relevant to searches for fifth forces or varying fundamental constants, with applications from astrophysics to laboratory spectroscopy experiments. We also provide a dedicated tool for the construction of hydrogenic transition amplitudes: “Computation of hydrogen radial INtegrals and COefficients” (CINCO).

Theoretical study of N(1535) and Σ*(1/2−) in the Cabibbo-favored process Λc+→pK¯0η

Motivated by the recent experimental measurements, we have investigated the Cabibbo-favored process Λc+→pK¯0η, where the N(1535) resonance is dynamically generated from the S-wave pseudoscalar meson-octet baryon interactions within the chiral unitary approach. The contributions from the intermediate N(1650) and the predicted low-lying baryon Σ*(1/2−) are also considered. In addition, a Breit-Wigner amplitude for the N(1535) resonance is checked. By comparing with the measured ηp, K¯0η, and pK¯0 invariant mass squared distributions, our results support the interpretation of N(1535) as a dynamically generated state. Furthermore, we demonstrate that, with the contribution from Σ*(1/2−) taken into account, the calculated invariant mass distributions agree with the Belle measurements. Future precise measurements of the Λc+→pK¯0η process can further elucidate the existence of the low-lying baryon Σ*(1/2−). Published by the American Physical Society 2024

Unleashing the power of EFT in neutrino-nucleus scattering

Neutrino physics is advancing into a precision era with the construction of new experiments, particularly in the few GeV energy range. Within this energy range, neutrinos exhibit diverse interactions with nucleons and nuclei. This study delves in particular into neutrino-nucleus quasi-elastic cross sections, taking into account both standard and, for the first time, non-standard interactions, all within the framework of effective field theory (EFT). The main uncertainties in these cross sections stem from uncertainties in the nucleon-level form factors, and from the approximations necessary to solve the nuclear many-body problem. We explore how these uncertainties influence the potential of neutrino experiments to probe new physics introduced by left-handed, right-handed, scalar, pseudoscalar, and tensor interactions. For some of these interactions the cross section is enhanced, making long-baseline experiments an excellent place to search for them. Our results, including tabulated cross sections for all interaction types and all neutrino flavors, can serve as the foundation for such searches.

Symmetric top molecule YbOCH[formula omitted] in the fundamental [formula omitted], [formula omitted]-violation searches

The symmetric top molecule YbOCH3 is studied for its potential to P, T-violation searches. The influence of the rotations and vibrations of the YbOCH3 on such violating effects as the electron electric dipole moment (eEDM) and the scalar–pseudoscalar electron-nucleon interaction (Ne-SPS) is studied using the coupled channels method. The corresponding sensitivity parameters Eeff and Es are computed.

Equation of spin motion for a particle with electric and magnetic charges and dipole moments

The general classical equation of spin motion is rigorously derived for a particle with electric and magnetic charges and electric and magnetic dipole moments in electromagnetic fields. The equation describing the spin motion relative to the momentum direction in storage rings is also obtained. The importance of the derivation follows from the potential presence of magnetic charges and EDMs due to the pseudoscalar CP-violating electromagnetic interaction caused by dark matter axions.

Unveiling chiral states in the XXZ chain: finite-size scaling probing symmetry-enriched c = 1 conformal field theories

We study the low-energy properties of the one-dimensional spin-1/2 XXZ chain with time-reversal symmetry-breaking pseudo-scalar chiral interaction and propose a phase diagram for the model. In the integrable case of the isotropic Heisenberg model with the chiral interaction, we employ the thermodynamic Bethe ansatz to find “chiralization”, the response of the ground state versus the strength of the pseudo-scalar chiral interaction of a chiral Heisenberg chain. Unlike the magnetization case, the chirality of the ground state remains zero until the transition point corresponding to critical coupling αc = 2J/π with J being the antiferromagnetic spin-exchange interaction. The central-charge c = 1 conformal field theories (CFTs) describe the two phases with zero and finite chirality. We show for this particular case and conjecture more generally for similar phase transitions that the difference between two emergent CFTs with identical central charges lies in the symmetry of their ground state (lightest weight) primary fields, i.e., the two phases are symmetry-enriched CFTs. At finite but small temperatures, the non-chiral Heisenberg phase acquires a finite chirality that scales with the temperature quadratically. We show that the finite-size effect around the transition point probes the transition.

Light thermal dark matter beyond p-wave annihilation in minimal Higgs portal model

This study explores a minimal renormalizable dark matter (DM) model, incorporating a sub-GeV Majorana DM and a singlet scalar particle ϕ. Using scalar and pseudo-scalar interactions (couplings cs and cp), we investigate implications for DM detection, considering s-wave, p-wave, and combined (s+p wave) contributions in DM annihilation cross-section, as well as loop-correction contributions to DM-nucleon elastic scattering. Identifying a broad parameter space (10 MeV < mχ ≲ mϕ) within the 2σ allowed region, we explore scenarios (|cs| ≫ |cp|, |cs| ≪ |cp|, and |cs| ≈ |cp|). We find that (i) a non-zero pseudo-scalar coupling alleviates direct detection constraints as a comparison with the previous pure scalar coupling case; (ii) CMB observations set stringent limits on pseudo-scalar interaction dominant cases, making s-wave annihilation viable only for mχ > 1 GeV; (iii) the preferred ϕ-resonance region can be tested in the future indirect detection experiments, such as e-ASTROGAM.

Study of the B−→K−ηηc decay due to the DD¯ bound state

We study the B−→K−ηηc decay by taking into account the S-wave contributions from the pseudoscalar meson-pseudoscalar meson interactions within the unitary coupled-channel approach, where the DD¯ bound state is dynamically generated. In addition, the contribution from the intermediate resonance K0*(1430)−, with K0*(1430)−→K−η, is also considered. Our results show that there is a clear peak around 3720 MeV in the ηηc invariant mass distribution, which could be associated with the DD¯ bound state. The future precise measurements of the B−→K−ηηc process at the Belle II and LHCb experiments could be, therefore, used to check the existence of the DD¯ bound state, and to deepen our understanding of the hadron-hadron interactions. Published by the American Physical Society 2024

Indirect detection of dark matter with (pseudo)-scalar interactions

Indirect detection is one of the most powerful methods to search for annihilating dark matter. In this work, we investigate the impact of non-perturbative effects in the indirect detection of dark matter. For this purpose we utilize a minimal model consisting of a fermionic dark matter candidate in the TeV mass range that interacts via scalar- and pseudo-scalar interactions with a massive scalar mediator mixing with the Higgs. The scalar interaction induces an attractive Yukawa potential between dark matter particles, such that annihilations are Sommerfeld enhanced, and bound states can form. These non-perturbative effects are systematically dealt with (potential) non-relativistic effective field theories and we derive the relevant cross sections for dark matter. We discuss their impact on the relic density and indirect detection. Annihilations in dwarf galaxies and the Galactic Center require special care and we derive generalized J-factors for these objects that account for the non-trivial velocity dependence of the cross sections in our model. We use limits on the gamma-ray flux based on Fermi-LAT observations and limits on the rate of exotic energy injection from Planck to derive bounds on the parameter space of the model. Finally, we estimate the impact that future limits from the Cherenkov Telescope Array are expected to have on the model.

Two-loop vertices with vacuum polarization insertion

We present the analytic evaluation of the second-order corrections to the massive form factors, due to two-loop vertex diagrams with a vacuum polarization insertion, with exact dependence on the external and internal fermion masses, and on the squared momentum transfer. We consider vector, axial-vector, scalar and pseudoscalar interactions between the external fermion and the external field. After renormalization, the finite expressions of the form factors are expressed in terms of polylogarithms up to weight three.

Hidden strange Bc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_{c}$$\\end{document}-like molecular states

With the chiral unitary approach, we evaluate the hidden strange Bc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_{c}$$\\end{document}-like molecular states of bc¯ss¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$b{\\bar{c}}s{\\bar{s}}$$\\end{document} systems B¯sD¯s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\bar{B}}_{s}{\\bar{D}}_{s}$$\\end{document}, B¯s∗D¯s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\bar{B}}_{s}^{*}{\\bar{D}}_{s}$$\\end{document}, B¯sD¯s∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\bar{B}}_{s}{\\bar{D}}_{s}^{*}$$\\end{document}, and B¯s∗D¯s∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\bar{B}}_{s}^{*}{\\bar{D}}_{s}^{*}$$\\end{document} coupled to the non-strange channels. The S-wave scattering amplitudes are calculated based on the vector meson exchange, four pseudoscalar mesons contact interactions, and four vector mesons contact interactions obtained from the extended local hidden gauge approach. We find six states below the threshold of the most relevant channel. The binding energies of these states are around 1–10 MeV and the widths are around 0.2–0.7 MeV. Our research is a supplement to the mass spectra of Bc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_{c}$$\\end{document}-like states, which may be useful for the experimental search in the future.

Exact solution of the 1D Dirac equation for a pseudoscalar interaction potential with the inverse-square-root variation law

We present the exact solution of the one-dimensional stationary Dirac equation for the pseudoscalar interaction potential, which consists of a constant and a term that varies in accordance with the inverse-square-root law. The general solution of the problem is written in terms of irreducible linear combinations of two Kummer confluent hypergeometric functions and two Hermite functions with non-integer indices. Depending on the value of the indicated constant, the effective potential for the Schrödinger-type equation to which the problem is reduced can form a barrier or well. This well can support an infinite number of bound states. We derive the exact equation for the energy spectrum and construct a rather accurate approximation for the energies of bound states. The Maslov index involved turns out to be non-trivial; it depends on the parameters of the potential.

Lepton flavor violating decays

A number of measurements in decays induced by the semileptonic b → s and b → c transitions hint towards a possible role of new physics in both sectors. Motivated by these anomalies, we investigate the lepton flavor violating decays. We calculate the two-fold angular distribution of decay in the presence of vector, axial-vector, scalar and pseudo-scalar new physics interactions. We then compute the branching fraction and lepton forward–backward asymmetry in the framework of vector leptoquark which is a viable solution to the current B anomalies. We find that the upper limits are and at 90% C.L.

Conditionally exactly solvable Dirac potential, including x 1/3 pseudoscalar interaction

We study the solution of the 1D Dirac equation for a pseudoscalar potential, which includes an interaction term proportional to and a term with a fixed strength. This is a conditionally exactly solvable singular potential, symmetric with respect to the origin. A feature of the potential is that the effective potential for the Schrödinger equation, to which the Dirac equation can be reduced, splits into two known potentials: the first Stillinger potential and the second Exton potential for the positive and negative semiaxes, respectively. We present the solution and analyze the energy spectrum and wave functions of the bound states. Our results reveal notable differences between the Schrödinger and Dirac behaviors.

Constraints on the axial-vector and pseudo-scalar mediated WIMP-nucleus interactions from PandaX-4T experiment

We present the constraints on the axial-vector and pseudo-scalar mediated WIMP-nucleus interactions from the PandaX-4T experiment, using the data set corresponding to a total exposure of 0.63 tonne⋅year. No significant signal excess is observed, and the most stringent constraints to date on the mediator mass are set for the axial-vector and pseudo-scalar simplified models. The maximum excluded mass of an axial-vector mediator is 825 GeV/c2 and that of a pseudo-scalar mediator is 106 GeV/c2. In addition, the upper limits on the spin-dependent WIMP-nucleon scattering cross-section for conventional neutron-only and proton-only interactions are derived.

Bound-state formation, dissociation and decays of darkonium with potential non-relativistic Yukawa theory for scalar and pseudoscalar mediators

Dark matter models with light mediators featuring sizable interactions among dark particles enjoy an increasing attention in the model building community due to the elegance with which they can potentially explain the scaling relations governing galactic halos and clusters of galaxies. In the present work we continue our study of such models using non-relativistic and potential non-relativistic effective field theories (NREFTs and pNREFTs) and explore the properties of a Yukawa-type model with scalar and pseudoscalar interactions between a low-energetic scalar mediator and heavy dark matter fermions. In particular, we make first steps towards the formulation of such theories at finite temperature by providing the thermal bound-state formation rate and the thermal break-up of bound states from the self-energies of the dark-pair fields, that interact with the thermal environment. We estimate numerically bound-state effects on the dark matter energy density, that provide up to a 35% correction depending on the relative size of the model couplings.

Pseudovector and pseudoscalar spin-dependent interactions in atoms

Hitherto unknown elementary particles can be searched for with atomic spectroscopy. We conduct such a search using a potential that results from the longitudinal polarization of a pseudovector particle. We show that such a potential, inversely proportional to the boson's mass squared, $V \propto 1/M^2$, can stay finite at $M \to 0$ if the theory is renormalizable. We also look for a pseudoscalar boson, which induces a contact spin-dependent potential that does not contribute to new forces searched for in experiments with macroscopic objects, but may be seen in atomic spectroscopy. We extract limits on the interaction constants of these potentials from the experimental spectra of antiprotonic helium, muonium, positronium, helium, and hydrogen.

Effective field theory of dark matter direct detection with collective excitations

We develop a framework for computing light dark matter direct detection rates through single phonon and magnon excitations via general effective operators. Our work generalizes previous calculations focused on spin-independent interactions involving the total nucleon and electron numbers $N$ (the usual route to excite phonons) and spin-dependent interactions involving the total electron spin $\mathbit{S}$ (the usual route to excite magnons), leading us to identify new responses involving the orbital angular momenta $\mathbit{L}$, as well as spin-orbit couplings $\mathbit{L}\ensuremath{\bigotimes}\mathbit{S}$ in the target. All four types of responses can excite phonons, while couplings to electron's $\mathbit{S}$ and $\mathbit{L}$ can also excite magnons. We apply the effective field theory approach to a set of well-motivated relativistic benchmark models, including (pseudo) scalar mediated interactions, and models where dark matter interacts via a multipole moment, such as a dark electric dipole, magnetic dipole or anapole moment. We find that couplings to pointlike degrees of freedom $N$ and $\mathbit{S}$ often dominate dark matter detection rates, implying that exotic materials with orbital $\mathbit{L}$ order or large spin-orbit couplings $\mathbit{L}\ensuremath{\bigotimes}\mathbit{S}$ are not necessary to have strong reach to a broad class of DM models. We highlight that phonon based crystal experiments in active R (such as SPICE) will probe light dark matter models well beyond those having a simple spin-independent interaction, including e.g., models with dipole and anapole interactions. Lastly, we make publicly available a code, $\mathsf{PhonoDark}$, which computes single phonon production rates in a wide variety of materials with the effective field theory framework.

Large-scale gauge spectra and pseudoscalar couplings

It is shown that the slopes of the superhorizon hypermagnetic spectra produced by the variation of the gauge couplings are practically unaffected by the relative strength of the parity-breaking terms. A new method is proposed for the estimate of the gauge power spectra in the presence of pseudoscalar interactions during inflation. To corroborate the general results, various concrete examples are explicitly analyzed. Since the large-scale gauge spectra also determine the late-time magnetic fields, it turns out that the pseudoscalar contributions have little impact on the magnetogenesis requirement. Conversely the parity-breaking terms crucially affect the gyrotropic spectra that may seed, in certain models, the baryon asymmetry of the Universe. In the most interesting regions of the parameter space, the modes reentering prior to symmetry breaking lead to a sufficiently large baryon asymmetry while the magnetic power spectra associated with the modes reentering after symmetry breaking may even be of the order of a few hundredths of a nG over typical length scales comparable with the Mpc prior to the collapse of the protogalaxy. From the viewpoint of the effective field theory description of magnetogenesis scenarios, these considerations hold generically for the whole class of inflationary models where the inflaton is not constrained by any underlying symmetry.

Electron beam dump constraints on light bosons with lepton flavor violating couplings

We study constraints on light and feebly interacting bosons having charged lepton flavor violating couplings from electron beam dump experiments. Scalar, pseudoscalar, vector, and dipole type interactions of the bosons are analyzed, and excluded regions from the searches for decays into electron-positron pairs are derived. It is found that parameter regions unconstrained by flavor violating decays of muon can be excluded using the results of the E137 experiment. We also discuss the impact of the search for flavor violating decays of the light bosons in electron beam dump experiments.