Violations Of Fundamental Symmetries Research Articles

Investigating the effects of Lorentz Invariance Violation on the CP-sensitivities of the Deep Underground Neutrino Experiment

The phenomena of neutrino oscillations offer a great potential for probing new-physics beyond the Standard Model. Any additional effects on neutrino oscillations can help understand the nature of the non-standard effects. The violation of fundamental symmetries may appear as a probe for new-physics in various neutrino experiments. Lorentz symmetry is one such fundamental symmetry in nature and the breakdown of spacetime is a possible motivation for a departure from the standard Lorentz symmetry picture. The Lorentz invariance violation (LIV) is intrinsic in nature and its effects exist even in a vacuum. Neutrinos can be an intriguing probe for exploring such violations of Lorentz symmetry. The effect of violation of Lorentz invariance can be explored through its impact on the neutrino oscillation probabilities. The effect of LIV is treated as a perturbation to the standard neutrino Hamiltonian considering the Standard Model Extension (SME) framework. In this work, we have probed the effects of LIV on the measurement of neutrino oscillation parameters considering Deep Underground Neutrino Experiment (DUNE) as a case study. The inclusion of LIV affects the measurements of various neutrino oscillation parameters as it modifies the standard neutrino oscillation probabilities. We looked into the capability of DUNE in constraining the LIV parameters and then explored the impact of CPT-violating LIV terms on the mass-induced neutrino oscillation probabilities. We have also probed the impact of LIV parameters on the CP-measurement sensitivities at DUNE.

Fundamental Physics with the Thermodynamically Stable Diatomic Trication UF3+

AbstractHighly‐charged UF3+, established by Helmut Schwarz and colleagues as the first thermodynamically stable diatomic trication, is investigated theoretically as a messenger for violations of fundamental symmetries, complementing the neutral, isoelectronic ThO, which experimentally gave one of the tightest bounds on violation of parity and time‐reversal symmetry. Electronic levels of UF3+ are analysed in comparison to the isoelectronic ions PaF2+ and ThF+. Non‐relativistic complete active space self‐consistent field calculations with scalar‐relativistic effective core potentials and a state‐optimized all‐electron two‐component complex Generalized Hartree‐Fock approach are employed to determine electronic states and properties relevant for tests of fundamental physics with these systems.

Molecular enhancement factors for the P,T -violating electric dipole moment of the electron in BaCH3 and YbCH3 symmetric top molecules

High-precision tests of fundamental symmetries are looking for the parity- ($\mathcal{P}$), time-reversal- ($\mathcal{T}$) violating electric dipole moment of the electron (eEDM) as proof of physics beyond the Standard Model. Particularly, in polyatomic molecules, the complex vibrational and rotational structure gives the possibility to reach high enhancement of the $\mathcal{P},\mathcal{T}$-odd effects in moderate electric fields, and with the possibility of increasing the statistical sensitivity by using laser cooling. In this work, we calculate the $\mathcal{P},\mathcal{T}$-odd molecular enhancement factor of the eEDM (${W}_{\mathrm{d}}$) and of the scalar-pseudoscalar interaction (${W}_{\mathrm{s}}$) necessary for the interpretation of future experiments on the promising candidates ${\mathrm{BaCH}}_{3}$ and ${\mathrm{YbCH}}_{3}$. We employ high-accuracy relativistic coupled cluster methods and systematically evaluate the uncertainties of our computational approach. Compared to other Ba- and Yb-containing molecules, ${\mathrm{BaCH}}_{3}$ and ${\mathrm{YbCH}}_{3}$ exhibit larger ${W}_{\mathrm{d}}$ and ${W}_{\mathrm{s}}$ associated to the increased covalent character of the $M$--C bond. The calculated values are $3.22\ifmmode\pm\else\textpm\fi{}0.12\ifmmode\times\else\texttimes\fi{}{10}^{24}\frac{h\text{Hz}}{e\text{cm}}$ and $13.80\ifmmode\pm\else\textpm\fi{}0.35\ifmmode\times\else\texttimes\fi{}{10}^{24}\frac{h\text{Hz}}{e\text{cm}}$ for ${W}_{\mathrm{d}}$, and $8.42\ifmmode\pm\else\textpm\fi{}0.29\phantom{\rule{4pt}{0ex}}h\mathrm{kHz}$ and $50.16\ifmmode\pm\else\textpm\fi{}1.27\phantom{\rule{4pt}{0ex}}h\mathrm{kHz}$ for ${W}_{\mathrm{s}}$, in ${\mathrm{BaCH}}_{3}$ and ${\mathrm{YbCH}}_{3}$, respectively. The robust, accurate, and cost-effective computational scheme reported in this work makes our results suitable for extracting the relevant fundamental properties from future measurements and also can be used to explore other polyatomic molecules sensitive to various violations of fundamental symmetries.

Measuring the stability of fundamental constants with a network of clocks

The detection of variations of fundamental constants of the Standard Model would provide us with compelling evidence of new physics, and could lift the veil on the nature of dark matter and dark energy. In this work, we discuss how a network of atomic and molecular clocks can be used to look for such variations with unprecedented sensitivity over a wide range of time scales. This is precisely the goal of the recently launched QSNET project: A network of clocks for measuring the stability of fundamental constants. QSNET will include state-of-the-art atomic clocks, but will also develop next-generation molecular and highly charged ion clocks with enhanced sensitivity to variations of fundamental constants. We describe the technological and scientific aims of QSNET and evaluate its expected performance. We show that in the range of parameters probed by QSNET, either we will discover new physics, or we will impose new constraints on violations of fundamental symmetries and a range of theories beyond the Standard Model, including dark matter and dark energy models.

Ab initio study and assignment of electronic states in molecular RaCl

Radium compounds have attracted recently considerable attention due to both development of experimental techniques for high-precision laser spectroscopy of molecules with short-lived nuclei and amenability of certain radium compounds for direct cooling with lasers. Currently, radium monofluoride (RaF) is one of the most studied molecules among the radium compounds, both theoretically and recently also experimentally. Complementary studies of further diatomic radium derivatives are highly desired to assess the influence of chemical substitution on diverse molecular parameters, especially on those connected with laser cooling, such as vibronic transition probabilities, and those related to violations of fundamental symmetries. In this article high-precision ab initio studies of electronic and vibronic levels of diatomic radium monochloride (RaCl) are presented. Recently developed approaches for treating electronic correlation with Fock-space coupled cluster methods are applied for this purpose. Theoretical results are compared to an early experimental investigation by Lagerqvist and used to partially reassign the experimentally observed transitions and molecular electronic levels of RaCl. Effective constants of P-odd hyperfine interaction Wa and P,T-odd scalar-pseudoscalar nucleus-electron interaction Ws in the ground electronic state of RaCl are estimated within the framework of a quasirelativistic Zeroth-Order Regular Approximation approach and compared to parameters in RaF and RaOH.

Probing Fundamental Symmetries of Deformed Nuclei in Symmetric Top Molecules

Precision measurements of Schiff moments in heavy, deformed nuclei are sensitive probes of beyond standard model T, P violation in the hadronic sector. While the most stringent limits on Schiff moments to date are set with diamagnetic atoms, polar polyatomic molecules can offer higher sensitivities with unique experimental advantages. In particular, symmetric top molecular ions possess K doublets of opposite parity with especially small splittings, leading to full polarization at low fields, internal comagnetometer states useful for rejection of systematic effects, and the ability to perform sensitive searches for T, P violation using a small number of trapped ions containing heavy exotic nuclei. We consider the symmetric top cation ^{225}RaOCH_{3}^{+} as a prototypical and candidate platform for performing sensitive nuclear Schiff measurements and characterize in detail its internal structure using relativistic abinitio methods. The combination of enhancements from a deformed nucleus, large polarizability, and unique molecular structure make this molecule a promising platform to search for fundamental symmetry violation even with a single trapped ion.

Coherent laser spectroscopy of highly charged ions using quantum logic.

Precision spectroscopy of atomic systems1 is an invaluable tool for the study of fundamental interactions and symmetries2. Recently, highly charged ions have been proposed to enable sensitive tests of physics beyond the standard model2-5 and the realization of high-accuracy atomic clocks3,5, owing to their high sensitivity to fundamental physics and insensitivity to external perturbations, which result from the high binding energies of their outer electrons. However, the implementation of these ideas has been hindered by the low spectroscopic accuracies (of the order of parts per million) achieved so far6-8. Here we cool trapped, highly charged argon ions to the lowest temperature reported so far, and study them using coherent laser spectroscopy, achieving an increase in precision of eight orders of magnitude. We use quantum logic spectroscopy9,10 to probe the forbidden optical transition in 40Ar13+ at a wavelength of 441nanometres and measure its excited-state lifetime and g-factor. Our work unlocks the potential of highly charged ions as ubiquitous atomic systems for use in quantum information processing, as frequency standards and in highly sensitive tests of fundamental physics, such as searches for dark-matter candidates11 or violations of fundamental symmetries2.

Actinide and lanthanide molecules to search for strong CP-violation.

The existence of the fundamental CP-violating interactions inside the nucleus leads to the existence of a nuclear Schiff moment. The Schiff moment potential corresponds to the electric field localized inside the nucleus and directed along its spin. This field can interact with electrons of an atom and induce the permanent electric dipole moment (EDM) of the whole system. The Schiff moment and the corresponding electric field are enhanced in the nuclei with octupole deformation leading to an enhanced atomic EDM. There is also a few-order enhancement of the T,P-violating effects in molecules due to the existence of energetically close levels of opposite parity. We study the Schiff moment enhancement in the class of diatomic molecules with octupole-deformed lanthanide and actinide nuclei: 227AcF, 227AcN, 227AcO+, 229ThO, 153EuO+ and 153EuN. Projecting the existing experimental achievements to measure the EDM in diamagnetic molecules with a spherical nucleus (205TlF) to the considered systems one can expect very high sensitivity to the quantum chromodynamics parameter [small theta, Greek, macron] and other hadronic CP-violation parameters surpassing the current best limits by several orders of magnitude. It can have a dramatic impact on the modern understanding of the nature of CP-violating fundamental interactions.

Caliope: a search for CPT-violation in o-ps

CALIOPE, or CP(T) Aberrant Leptons in ortho-Positronium Experiment, is a tabletop search for fundamental symmetry violations, including CP- and CPT-violation, in ortho-positronium (o-Ps). We use a tagged 22Na source adjacent to a cylinder of aerogel to generate o-Ps at the center of a cylindrical array of 24 NaI(Tl) bars. We search for CPT - violating angular correlations in the gamma rays emitted in the decay of o-Ps. With an angular acceptance of 75% of 4π, and the ability to acquire statistics over a longer period of time, CALIOPE will improve upon the limit set by previous experiments. The experimental setup can also be used in a search for CP-violation in o-Ps with the addition of an electromagnet. We describe the design of the experiment, results from a characterization of the systematics for the CPT- and CP-violating measurements, and a demonstration of the DAQ.

The role of Lattice QCD in searches for violations of fundamental symmetries and signals for new physics

This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for Lattice Quantum Chromodynamics (LQCD) in the research frontier in fundamental symmetries and signals for new physics. LQCD, in synergy with effective field theories and nuclear many-body studies, provides theoretical support to ongoing and planned experimental programs in searches for electric dipole moments of the nucleon, nuclei and atoms, decay of the proton, $n$-$\overline{n}$ oscillations, neutrinoless double-$\beta$ decay of a nucleus, conversion of muon to electron, precision measurements of weak decays of the nucleon and of nuclei, precision isotope-shift spectroscopy, as well as direct dark matter detection experiments using nuclear targets. This whitepaper details the objectives of the LQCD program in the area of Fundamental Symmetries within the USQCD collaboration, identifies priorities that can be addressed within the next five years, and elaborates on the areas that will likely demand a high degree of innovation in both numerical and analytical frontiers of the LQCD research.

RaH as a potential candidate for electron electric-dipole-moment searches

Diatomic polar molecules have been the focus of research in the recent past as candidates for electron electric dipole moment (eEDM), de, measurements. In the present work, we focus on RaH molecule and have calculated three of its properties (in the X2Σ+ state) the effective electric field (Eeff), the scalar-pseudoscalar (S-PS) interaction coefficient (Ws,A), and permanent electric dipole moment (PDM) that play crucial roles in probing fundamental symmetry violations. The calculations were based on the relativistic coupled-cluster singles and doubles (RCCSD) frame work. Our results for Eeff, Ws,A, and PDM are 80.31 GV/cm, 216.82 kHz, and 4.44 D respectively. In addition to possessing high magnitudes of Eeff and Ws,A, RaH also has a large PDM, which is a highly desirable criterion for eEDM experiments. The analysis of our results clearly indicates the spectacular role of electron correlation in enhancing their magnitudes ≈16% for PDM and ≈31% for Eeff and Ws,A. The ratio of Eeff to Ws,A for RaH is 89.56×1018e−1 cm−1. Based on our results and other experimental considerations, we propose RaH as a future candidate for experiments in this field.

Kaon decay studies at CERN SPS in the last decades

This review summarizes the kaon experimental results obtained in the last 15 years on the basis of data collected on the SPS in CERN with a participance of JINR physicists. These results contribute essentially into the Standard Model checks and search for its extension, fundamental symmetry violations and low energy strong interactions theory development. A progress in the experimental technique and prospects for the future results are also discussed.

Solar neutrinos and neutrino physics

Solar neutrino studies triggered and largely motivated the major developments in neutrino physics in the last 50 years. Theory of neutrino propagation in different media with matter and fields has been elaborated. It includes oscillations in vacuum and matter, resonance flavor conversion and resonance oscillations, spin and spin-flavor precession, etc. LMA MSW has been established as the true solution of the solar neutrino problem. Parameters theta12 and Delta_m21^2 have been measured; theta13 extracted from the solar data is in agreement with results from reactor experiments. Solar neutrino studies provide a sensitive way to test theory of neutrino oscillations and conversion. Characterized by long baseline, huge fluxes and low energies they are a powerful set-up to search for new physics beyond the standard 3nu paradigm: new neutrino states, sterile neutrinos, non-standard neutrino interactions, effects of violation of fundamental symmetries, new dynamics of neutrino propagation, probes of space and time. These searches allow us to get stringent, and in some cases unique bounds on new physics. We summarize the results on physics of propagation, neutrino properties and physics beyond the standard model obtained from studies of solar neutrinos.

Measurement of electric dipole moments at storage rings

The electric dipole moment (EDM) is a fundamental property of a particle, like mass, charge and magnetic moment. What makes this property in particular interesting is the fact that a fundamental particle can only acquire an EDM via and violating processes. EDM measurements contribute to the understanding of the matter over anti-matter dominance in the universe, a question closely related to the violation of fundamental symmetries. Up to now measurements of EDMs have concentrated on neutral particles. Charged particle EDMs can be measured at storage ring. Plans at Forschungszentrum Jülich and results of first test measurements at the COoler SYnchrotron COSY will be presented.

Testing Lorentz invariance in the weak decay of polarized atoms

Symmetries of space time, and Lorentz and CPT symmetry in particular, are a cornerstone of modern physics and lie at the foundation of quantum field theory (QFT) and Einstein's theory of general relativity, the two most successful theories in physics which together describe the four fundamental forces of nature. However, the inability to incorporate gravity as described by general relativity into the QFT standard model of particle physics, which very successfully combines the electromagnetic, strong and weak interactions, has led to the development of alternative so-called Grand Unified Theories (GUTs) or theories of quantum gravity. Since many of these theories break Lorentz symmetry at some small level 1-4, experimental searches for Lorentz-violating effects could help shed light on new physics beyond the standard model (SM) and provide clues as to the nature of quantum gravity. Parameterization of such effects within the Lorentz-violating Standard Model Extension (SME) developed by A. Kostelecky 5 has allowed direct comparison of many experiments, ranging from table-top precision measurements to observations of ultra-high energy cosmic and gamma rays to astrophysical observations. The SME has proven to be a remarkable tool in the search for Lorentz violation across the landscape of experimental physics. Up until the present, experimental results have taken the form of upper bounds on the SME coefficients and are tabulated in the Data Tables for Lorentz and CPT Violation 6. On a closer look, however, Lorentz invariance has been tested poorly in the weak interaction 7, 8, which is all the more surprising since violations of fundamental symmetries could be observed only in the weak sector: The first discovery of a violation of presumed (discrete) space-time symmetry was that of parity violation in nuclear β decay 9. C. S. Wu and her collaborators found that when a specific nucleus (60Co) was placed in a magnetic field, electrons from the beta decay were preferentially emitted in the direction opposite that of the aligned angular momentum of the nucleus. When it is possible to distinguish these two cases in a mirror, parity is not conserved. If the mirror not only reverses spatial direction but also changes matter to antimatter, then the experiment in front of the mirror would look just like its mirror image. The separate violations of P symmetry and C symmetry cancel to preserve CP symmetry. These symmetry violations arise only from the weak interaction, not from the strong and electromagnetic interactions, and therefore shows up strongly only in beta decay. Until 1964 it was thought that the combination CP was a valid symmetry of the Universe. That year, Christenson, Cronin, Fitch, and Turlay performed their historic experiment to see if the long-lived neutral K meson could occasionally decay to π+ π−. They found that indeed it did 10! And the observed CP violation implies, by CPT invariance, violations of T-symmetry as well.

ON WEAK INTERACTIONS AS SHORT-DISTANCE MANIFESTATIONS OF GRAVITY

We conjecture that weak interactions are peculiar manifestations of quantum gravity at the Fermi scale, and that the Fermi constant is related to the Newtonian constant of gravitation. In this framework one may understand the violations of fundamental symmetries by the weak interactions, in particular parity violations, as due to fluctuations of the spacetime geometry at a Planck scale coinciding with the Fermi scale. As a consequence, gravitational phenomena should play a more important role in the microworld, and experimental settings are suggested to test this hypothesis.

Special Issue: Seventh congress of the international society for theoretical chemical physics

This volume collects 58 selected papers from the scientific contributions presented at the Seventh Congress of the International Society for Theoretical Chemical Physics (ISTCP-VII), organized by t ...

Proposed search forT-odd,P-even interactions in spectra of chaotic atoms

Violation of fundamental symmetries in atoms is the subject of intense experimental and theoretical interest. P-odd, T-even transitions have been observed and are in excellent agreement with electroweak theory. Searches for permanent electric dipole moments have placed bounds on T-odd, P-odd interactions, constraining proposed extensions to the Standard Model of elementary particles. Here we propose a new search for T-odd, P-even (TOPE) interactions in atoms. We consider open-shell atoms, such as the rare-earth atoms, which have dense, chaotic excitation spectra with strong level repulsion. The strength of the level repulsion depends on the underlying symmetries of the atomic Hamiltonian. TOPE interactions lead to enhanced level repulsion. We demonstrate how a statistical analysis of many chaotic spectra can determine the strength of level repulsion; in particular, the variance of the number of levels in an energy range has been shown to be a useful measure. We estimate that, using frequency comb spectroscopy, a sufficient number of chaotic levels could be measured to match or exceed the current experimental bounds on TOPE interactions.

Testing discrete symmetries with the cosmic microwave background: current constraints and Planck forecasts

Anisotropy and polarization of the CMB are probing cosmological models with unprecedented precision. The WMAP satellite data are largely consistent with concordance ACDM cosmology. However, intriguing flukes are known to exist that may pinpoint at physics beyond the standard model. Constraining the violations of discrete symmetries in the CMB pattern is a promising mean to investigate these discrepancies.In this paper we constrain the Parity and \U0001d49e\U0001d4b1\U0001d4af symmetries through CMB datasets. We describe the basic formalism, the relevant estimators and the overall analysis strategy. We provide marginal evidence for large scale Parity anomaly in the WMAP data that may be soon confirmed or discarded by the Planck satellite. Planck is currently measuring CMB anisotropies and their polarization with a level of precision that will remain unparalleled for many years to come. We also show how the CMB can be used to constrain fundamental symmetry violations in the photon sector through the so-called cosmological birefringence phenomenon. Finally, we provide forecasts for Planck and we discuss how emission from a specific diffuse foreground component arising within the Solar System needs to be kept under strict control to avoid incurring into false positive detections.

Search for variation of fundamental constants and violations of fundamental symmetries using isotope comparisons

Atomic microwave clocks based on hyperfine transitions, such as the caesium standard, tick with a frequency that is proportional to the magnetic moment of the nucleus. This magnetic moment varies strongly between isotopes of the same atom, while all atomic electron parameters remain the same. Therefore the comparison of two microwave clocks based on different isotopes of the same atom can be used to constrain variation of fundamental constants. In this paper we calculate the neutron and proton contributions to the nuclear magnetic moments, as well as their sensitivity to any potential quark mass variation, in a number of isotopes of experimental interest including 201,199Hg and 87,85Rb, where experiments are underway. We also include a brief treatment of the dependence of the hyperfine transitions to variation in nuclear radius, which in turn is proportional to any change in quark mass. Our calculations of expectation-values of proton and neutron spin in nuclei are also needed to interpret measurements of violations of fundamental symmetries.