Parity Violation Research Articles

Challenges in the extraction of physics beyond the Standard Model from electron scattering

Abstract Precise measurements of electron and positron scattering, including parity violation, offer great promise in the search for physics beyond the Standard Model. In this context it is crucial to understand the corrections which might arise from charge symmetry violation, as well as the less well known strange and charm quark distributions. Our analysis, using state of the art parton distributions, suggests that these contributions lead to corrections in the extraction of the weak couplings $g^{eq}_{AV}$ and $g^{eq}_{VA}$ of the order $(1-2)\%$, while they are as large as $4\%$ for $g^{eq}_{AA}$, at a typical scale of $Q^2 = 10\ {\rm GeV}^2$. These results underline the importance of carrying out high precision measurements, which will not only provide information on physics beyond the Standard Model but also reduce the current uncertainties on our knowledge of the strange and charm quark distributions in the proton.

Constraining P and T violating forces with chiral molecules

New sources of parity and time-reversal violation are predicted by well motivated extensions of the Standard Model and can be effectively probed by precision spectroscopy of atoms and molecules. Chiral molecules have distinguished enantiomers which are related by parity transformation. Thus they are promising candidates to search for parity violation at molecular scales, which has yet to be observed. In this work, we show that precision spectroscopy of the hyperfine structure of chiral molecules is sensitive to new physics sources of parity and time-reversal violation. In particular, such a study can be sensitive to regions unexplored by terrestrial experiments of a new chiral spin-1 particle that couples to nucleons. We explore the potential to hunt for time-reversal violation in chiral molecules and show that it can be a complementary measurement to other probes. We assess the feasibility of such hyperfine metrology and project the sensitivity in CHDBrI+. Published by the American Physical Society 2024

Studies of Parity Violation in Atoms

AbstractStudies of the effects of the weak interaction in atomic systems provide tests of the Standard Model of particle physics, and explore physics scenarios beyond the Standard Model. In addition, these studies can offer valuable insights into low‐energy nuclear physics. An overview of the field of atomic parity violation is provided, and implications to nuclear and particle physics and ongoing experimental efforts are discussed. Furthermore, the plans for precision measurements of the signatures of the weak interaction in atomic ytterbium are discussed.

Cosmic topology. Part IIIa. Microwave background parity violation without parity-violating microphysics

The standard cosmological model, which assumes statistical isotropy and parity invariance, predicts the absence of correlations between even-parity and odd-parity observables of the cosmic microwave background (CMB).Contrary to these predictions, large-angle CMB temperature anomalies generically involve correlations between even-ℓ and odd-ℓ angular power spectrum C ℓ , while recent analyses of CMB polarization have revealed non-zero equal-ℓ EB correlations.These findings challenge the conventional understanding, suggesting deviations from statistical isotropy, violations of parity, or both.Cosmic topology, which involves changing only the boundary conditions of space relative to standard cosmology, offers a compelling framework to potentially account for such parity-violating observations.Topology inherently breaks statistical isotropy, and can also break homogeneity and parity, providing a natural paradigm for explaining observations of parity-breaking observables without the need to add parity violation to the underlying microphysics.Our investigation delves into the harmonic space implications of topology for CMB correlations, using as an illustrative example EB correlations generated by tensor perturbations under both parity-preserving and parity-violating scenarios.Consequently, these findings not only challenge the foundational assumptions of the standard cosmological model but also open new avenues for exploring the topological structure of the Universe through CMB observations.

Making sense of ghosts

Ghosts have been a stumbling block in the development of a UV complete quantum field theory for gravity. We discuss how difficulties associated with ghosts are overcome in the context of 0+1d QFT. Obtaining a probability interpretation is the key issue, and for this we discuss how an appropriate inner product can be constructed to define a sensible Born rule. Ghost theories are intrinsically unitary and perturbatively stable. They can also display nonperburbative stability even when the corresponding normal theory does not. The spectra and propagators are numerically obtained at both weak and strong coupling. Normalizable wave functions are obtained for the energy eigenstates and they show a violation of normal parity. We discuss connections to PT-symmetric quantum mechanics.

The glow of axion quark nugget dark matter

Context. The existence of axion quark nuggets is a potential consequence of the axion field, which provides a possible solution to the charge-conjugation parity violation in quantum chromodynamics. In addition to explaining the cosmological discrepancy of matter-antimatter asymmetry and a visible-to-dark-matter ratio of Ωdark/Ωvisible ≃ 5, these composite compact objects are expected to represent a potentially ubiquitous electromagnetic background radiation by interacting with ordinary baryonic matter. We conducted an in-depth analysis of axion quark nugget-baryonic matter interactions in the environment of the intracluster medium in the constrained cosmological Simulation of the LOcal Web (SLOW). Aims. Here, we aim to provide upper limit predictions on electromagnetic counterparts of axion quark nuggets in the environment of galaxy clusters by inferring their thermal and non-thermal emission spectrum originating from axion quark nugget-cluster gas interactions. Methods. We analyzed the emission of axion quark nuggets in a large sample of 161 simulated galaxy clusters using the SLOW simulation. These clusters are divided into a sub-sample of 150 galaxy clusters, ordered in five mass bins ranging from 0.8 to 31.7 × 1014 M⊙, along with 11 cross-identified galaxy clusters from observations. We investigated dark matter-baryonic matter interactions in galaxy clusters in their present stage at the redshift of z = 0 by assuming all dark matter consists of axion quark nuggets. The resulting electromagnetic signatures were compared to thermal Bremsstrahlung and non-thermal cosmic ray (CR) synchrotron emission in each galaxy cluster. We further investigated individual frequency bands imitating the observable range of the WMAP, Planck, Euclid, and XRISM telescopes for the most promising cross-identified galaxy clusters hosting detectable signatures of axion quark nugget emission. Results. We observed a positive excess in the low- and high-energy frequency windows, where thermal and non-thermal axion quark nugget emission can significantly contribute to (or even outshine) the emission of the intracluster medium (ICM) in frequencies up to νT ≲ 3842.19 GHz and νT ϵ [3.97, 10.99] × 1010GHz, respectively. Emission signatures of axion quark nuggets are found to be observable if CR synchrotron emission of individual clusters is sufficiently low. The degeneracy in the parameters contributing to an emission excess makes it challenging to offer predictions with respect to pinpointing specific regions of a positive axion quark nugget excess; however, a general increase in the total galaxy cluster emission is expected based on this dark matter model. Axion quark nuggets constitute an increment of 4.80% of the total galaxy cluster emission in the low-energy regime of νT ≲ 3842.19 GHz for a selection of cross-identified galaxy clusters. We propose that the Fornax and Virgo clusters represent the most promising candidates in the search for axion quark nugget emission signatures. Conclusions. The results from our simulations point towards the possibility of detecting an axion quark nugget excess in galaxy clusters in observations if their signatures can be sufficiently disentangled from the ICM radiation. While this model proposes a promising explanation for the composition of dark matter, with the potential to have this outcome verified by observations, we propose further changes that are aimed at refining our methods. Our ultimate goal is to identify the extracted electromagnetic counterparts of axion quark nuggets with even greater precision in the near future.

DMRG-Tailored Coupled Cluster Method in the 4c-Relativistic Domain: General Implementation and Application to the NUHFI and NUF3 Molecules.

Heavy atom compounds represent a challenge for computational chemistry due to the need for simultaneous treatment of relativistic and correlation effects. Often such systems also exhibit strong correlation, which hampers the application of perturbation theory or single-reference coupled cluster (CC) methods. As a viable alternative, we have proposed externally correcting the CC method using the density matrix renormalization group (DMRG) wave functions, yielding the DMRG-tailored CC method. In a previous paper [J. Chem. Phys. 2020, 152, 174107], we reported a first implementation of this method in the relativistic context, which was restricted to molecules with real double group symmetry. In this work, we present a fully general implementation of the method, covering complex and quaternion double groups as well. The 4c-TCC method thus becomes applicable to polyatomic molecules, including heavy atoms. For the assessment of the method, we performed calculations of the chiral uranium compound NUHFI, which was previously studied in the context of the enhancement of parity violation effects. In particular, we performed calculations of a cut of the potential energy surface of this molecule along the stretching of the N-U bond, where the system exhibits strong multireference character. Since there are no experimental data for NUHFI, we have performed also an analogous study of the (more symmetric) NUF3 molecule, where the vibrational frequency of the N-U bond can be compared with spectroscopic data.

Apparent Parity Violation in the Observed Galaxy Trispectrum.

Recent measurements of the four-point correlation function in large-scale galaxy surveys have found apparent evidence of parity violation in the distribution of galaxies. This cannot happen via dynamical gravitational effects in general relativity. If such a violation arose from physics in the early Universe it could indicate important new physics beyond the standard model, and would be at odds with most models of inflation. It is therefore now timely to consider the galaxy trispectrum in more detail. While the intrinsic four-point correlation function, or equivalently the trispectrum, its Fourier counterpart, is parity invariant, the observed trispectrum must take redshift-space distortions into account. Although the standard Newtonian correction also respects parity invariance, we show that subleading relativistic corrections do not. We demonstrate that these can be significant at intermediate linear scales and are dominant over the Newtonian parity-invariant part around the equality scale and above. Therefore when observing the galaxy four-point correlation function, we should expect to detect parity violation on large scales.

Constraints on parity and Lorentz violations in gravity from GWTC-3 through a parametrization of modified gravitational wave propagations

Constraints on parity and Lorentz violations in gravity from GWTC-3 through a parametrization of modified gravitational wave propagations

Evolution and fluctuations of chiral chemical potential in heavy ion collisions

The possible appearance of the effects of local parity breaking in the QCD medium formed in heavy ion collisions due to violation of chiral symmetry can be quantified by corresponding chiral chemical potential [Formula: see text]. The experimental observables sensitive to the effects of local parity violation in strong interaction include search for polarization splitting of the [Formula: see text] and [Formula: see text] mesons via angular dependence of spectral functions in their decay to leptons. In this paper, we study the space-time evolution and fluctuations of [Formula: see text] using relativistic hydrodynamics and estimate their effect on the light vector meson polarization splitting in Pb–Pb collisions at LHC energy.

Parity-violating scalar-tensor theory

We investigate the parity-violating scalar-tensor theory and pay special attention to terms that are free of the Ostrogradsky ghost in the unitary gauge, i.e., when the scalar field possesses a timelike gradient. We exhaustively identify the generally covariant scalar-tensor theory (GST) monomials with parity violation up to d=4, where d is the total number of derivatives in the unitary gauge. According to the correspondence between GST terms and the spatially covariant gravity (SCG) terms in the unitary gauge, we also exhaustively identify the SCG monomials with parity violation up to d=4, where the Lie derivatives of the extrinsic curvature and the lapse function are necessarily introduced. We find a total of nine independent parity-violating SCG monomials, of which seven contain no higher-order Lie derivatives and are thus automatically free of ghosts, while two involve Lie derivatives of the extrinsic curvature and the lapse function and are thus potentially dangerous. By explicitly deriving their generally covariant correspondence, we obtain seven independent scalar-tensor terms dubbed the “Qi-Xiu” Lagrangians, which are the most general parity-violating scalar-tensor theories that are ghost-free in the unitary gauge up to d=4. Our results include the existing theories in the literature, such as the Chern-Simons term and the chiral scalar-tensor theories, as special cases. Published by the American Physical Society 2024

Unlocking the hidden dimension: power of chirality in scientific exploration.

In the boundless landscape of scientific exploration, there exists a hidden, yet easily accessible, dimension that has often not only intrigued and puzzled researchers but also provided the key. This dimension is chirality, the property that describes the handedness of objects. The influence of chirality extends across diverse fields of study from the parity violation in electroweak interactions to the extremely large macroscopic systems such as galaxies. In this opinion piece, we will delve into the power of chirality in scientific exploration by examining some examples that, at different scales, demonstrate its role as a key to a better understanding of our world. Our goal is to incite researchers from all fields to seek, implement and utilize chirality in their research. Going this extra mile might be more rewarding than it seems at first glance, in particular with regard to the increasing demand for new functional materials in response to the contemporary scientific and technological challenges we are facing. This article is part of the theme issue 'Celebrating the 15th anniversary of the Royal Society Newton International Fellowship'.

Compatibility of Gravitational Baryogenesis with theoretical framework of [formula omitted] Gravity

The primary goal of this article is to analyze the disproportion between matter and antimatter in the Universe using the phenomenon of gravitational baryogenesis under the framework of f(R,G,T) gravity, where R, G and T are Ricci Scalar, Gauss–Bonnet invariant and the trace of energy momentum tensor. This phenomenon based on charge parity violation interactions and in this article we generate it through the coupling between the baryon matter current (Jν) and ∂ν(R+G+T) as well as for generalized case with (Jν) and ∂νf(R+G+T). We evaluate the ratio ηBS (baryon to entropy) of the propose model of f(R,G,T) gravity for gravitational baryogenesis and generalized gravitational baryogenesis with power-law form consideration for the scale factor in different eras of the Universe. We notice that the results of (ηBS) are compatible with its observational bound under the optimal choice of model parameters and hence we say that this gravity is good for gravitational baryogenesis under certain constraints of model parameters.

Kalb-Ramond field and gravitational parity violation

Kalb-Ramond field and gravitational parity violation

Near-complete chiral selection in rotational quantum states

Controlling the internal quantum states of chiral molecules for a selected enantiomer has a wide range of fundamental applications from collision and reaction studies, quantum information to precision spectroscopy. Achieving full enantiomer-specific state transfer is a key requirement for such applications. Using tailored microwave fields, a chosen rotational state can be enriched for a selected enantiomer, even starting from a racemic mixture. This enables rapid switching between samples of different enantiomers in a given state, holding great promise, for instance, for measuring parity violation in chiral molecules. Although perfect state-specific enantiomeric enrichment is theoretically feasible, achieving the required experimental conditions seemed unrealistic. Here, we realize near-ideal conditions, overcoming both the limitations of thermal population and spatial degeneracy in rotational states. We achieve over 92% enantiomer-specific state transfer efficiency using enantiopure samples. This indicates that 96% state-specific enantiomeric purity can be obtained from a racemic mixture, in an approach that is universally applicable to all chiral molecules of C1 symmetry. Our work integrates the control over internal quantum states with molecular chirality, thus expanding the field of state-selective molecular beams studies to include chiral research.

Refined determination of the weak mixing angle at low energy

The weak mixing angle is a fundamental parameter of the electroweak theory of the standard model whose measurement in the low-energy regime is still not precisely determined. Different probes are sensitive to its value, including atomic parity violation, coherent elastic neutrino-nucleus scattering, and parity-violating electron scattering on different nuclei. In this work, we attempt for the first time to combine all these various determinations by performing a global fit that also takes into account the unavoidable dependence on the experimentally poorly known neutron distribution radius of the nuclei employed, for which a new measurement using proton-cesium elastic scattering became available. By using all present direct determinations of the neutron distribution radius of cesium, we find sin2ϑW=0.2396−0.0019+0.0020, which should supersede the previous value determined from atomic parity violation on cesium. When including electroweak only, but also indirect, determinations of the neutron distribution radius of cesium, the uncertainty reduces to 0.0017, maintaining the same central value and showing excellent agreement independently of the method used. Published by the American Physical Society 2024

Parity-Odd power spectra: Concise statistics for cosmological parity violation

Abstract We introduce the Parity-Odd Power (POP) spectra, a novel set of observables for probing parity violation in cosmological N-point statistics. POP spectra are derived from composite fields obtained by applying nonlinear transformations, involving also gradients, curls, and filtering functions, to a scalar field. This compresses the parity-odd trispectrum into a power spectrum. These new statistics offer several advantages: they are computationally fast to construct, estimating their covariance is less demanding compared to estimating that of the full parity-odd trispectrum, and they are simple to model theoretically. We measure the POP spectra on simulations of a scalar field with a specific parity-odd trispectrum shape. We compare these measurements to semi-analytic theoretical calculations and find agreement. We also explore extensions and generalizations of these parity-odd observables.

No evidence for parity violation in BOSS

Recent studies have found evidence for parity violation in the BOSS spectroscopic galaxy survey, with statistical significance as high as 7σ. These analyses assess the significance of the parity-odd four-point correlation function (4PCF) with a statistic called X 2. This statistic is biased if the parity-even eight-point correlation function (8PCF) of the data differs from the mock catalogs. We construct new statistics X 2 ×, X 2 null that separate the parity violation signal from the 8PCF bias term, allowing them to be jointly constrained. Applying these statistics to BOSS, we find that the parity violation signal ranges from 0 to 2.5σ depending on analysis choices, whereas the 8PCF bias term is ~ 6σ. We conclude that there is no compelling evidence for parity violation in BOSS. Our new statistics can be used to search for parity violation in future surveys, such as DESI, without 8PCF biases.

Scalar induced gravitational waves in chiral scalar–tensor theory of gravity

We study the scalar induced gravitational waves (SIGWs) from a chiral scalar–tensor theory of gravity. The parity-violating (PV) Lagrangian contains the Chern–Simons (CS) term and PV scalar–tensor terms, which are built of the quadratic Riemann tensor term and first-order derivatives of a scalar field. We consider SIGWs in two cases, in which the semi-analytic expression to calculate SIGWs can be obtained. Then, we calculate the fractional energy density of SIGWs with a monochromatic power spectrum for the curvature perturbation. We find that the SIGWs in chiral scalar–tensor gravity behave differently from those in GR before and after the peak frequency, which results in a large degree of circular polarization.

Electroweak Nuclear Properties from Single Molecular Ions in a Penning Trap.

We present a novel technique to probe electroweak nuclear properties by measuring parity violation (PV) in single molecular ions in a Penning trap. The trap's strong magnetic field Zeeman shifts opposite-parity rotational and hyperfine molecular states into near degeneracy. The weak interaction-induced mixing between these degenerate states can be larger than in atoms by more than 12 orders of magnitude, thereby vastly amplifying PV effects. The single molecule sensitivity would be suitable for applications to nuclei across the nuclear chart, including rare and unstable nuclei.