T-invariance Violation Research Articles

Double polarized deuteron–deuteron scattering and test of T-invariance

A component of the total cross section of the deuteron-deuteron interaction connected with the vector polarized ([Formula: see text]) one initial deuteron and tensor polarized ([Formula: see text]) another one constitutes a null-test signal of the T-invariance violation but P-parity conservation. The energy dependence of this signal is calculated here at beam kinetic energies per nucleon of 0.1–1[Formula: see text]GeV within the Glauber spin-dependent theory of multiple scattering in the S-wave approximation for the deuteron wave function.

Experimental test of an extension of the Rosenzweig-Porter model to mixed integrable-chaotic systems experiencing time-reversal invariance violation

Abstract We report on the theoretical and experimental investigation of the transition of a typical quantum system with mixed regular-integrable classical dynamics to one with violated time-reversal (T) invariance. The measurements are performed with a flat superconducting microwave resonator with circular shape in which chaoticity is induced by using either long antennas or inserting two circular disks into the cavity, and by magnetizing a ferrite disk placed at its center, which leads to violation of T invariance. We propose an extension of the Rosenzweig-Porter (RP) model, which interpolates between mixed regular-chaotic instead of integrable dynamics and fully chaotic dynamics with violated T-invariance, and derive a Wigner-surmise like analytical expression for the corresponding nearest-neighbor spacing distribution. We propose a procedure involving this result and those for the RP model to determine the size of T-invariance violation and chaoticity and validate it employing the experimental eigenfrequency spectra.

Effect of T-Invariance Violation in Scattering of Polarized 3He Nuclei on Tensor-Polarized Deuterons

In the interaction of a transversely polarized nuclear beam with a tensor-polarized deuteron target, a nonzero value of the component of the total cross section corresponding to this combination of polarizations is an unambiguous signal ofT-invariance violation whileP-parity is preserved. The method developed earlier for calculating this component of the total cross section forpdscattering based on the Glauber theory has been generalized by us to the case of3Hedscattering, and its energy dependence in the range of beam energies 0.1–1 GeV/nucleon has been calculated. It is found that in3Hedcollisions, in contrast topdscattering, the contribution of only one type ofT-violating nucleon-nucleon forces dominates, which is essential for extraction of the unknown constant of this interaction from the corresponding data.

Effect of T-Invariance Violation in Scattering of Polarized 3He Nuclei on Tensor-Polarized Deuterons

Effect of T-Invariance Violation in Scattering of Polarized 3He Nuclei on Tensor-Polarized Deuterons

Possible Studies at the First Stage of the NICA Collider Operation with Polarized and Unpolarized Proton and Deuteron Beams

This paper contains suggestions for experiments with usage of the Spin Physics Detector (SPD) at the first stage of the SPD NICA Programme developing at JINR. Double polarized pp-, dd- and pd- collisions at c.m.s. NN energies of 3.4-10 GeV, which will be accessible at the initial stage of experiments, allow one to study spin dependence of the NN interaction, search for multiquark states at double strangeness, charm and beauty thresholds, study the short-range structure of the deuteron. Double polarized pd scattering offer a possibility to test the Standard Model through the search for T-invariance violation.

How time-reversal-invariance violation leads to enhanced backscattering with increasing openness of a wave-chaotic system.

We report on the experimental investigation of the dependence of the elastic enhancement, i.e., enhancement of scattering in the backward direction over scattering in other directions, of a wave-chaotic system with partially violated time-reversal (T) invariance on its openness. The elastic enhancement factor is a characteristic of quantum chaotic scattering which is of particular importance in experiments, like compound-nuclear reactions, where only cross sections, i.e., the moduli of the associated scattering matrix elements, are accessible. In the experiment a quantum billiard with the shape of a quarter bow tie, which generates a chaotic dynamics, is emulated by a flat microwave cavity. Partial T-invariance violation of varying strength 0≤ξ≲1 is induced by two magnetized ferrites. The openness is controlled by increasing the number M of open channels, 2≤M≤9, while keeping the internal absorption unchanged. We investigate the elastic enhancement as function of ξ and find that for a fixed M it decreases with increasing T-invariance violation, whereas it increases with increasing openness beyond a certain value of ξ≳0.2. The latter result is surprising because it is opposite to that observed in systems with preserved Tinvariance (ξ=0). We come to the conclusion that the effect of T-invariance violation on the elastic enhancement then dominates over the openness, which is crucial for experiments which rely on enhanced backscattering, since, generally, a decrease of the openness is unfeasible. Motivated by these experimental results, we performed theoretical investigations based on random matrix theory which confirm our findings.

Critical Comments on the T-Null Theorem and New Approach to Searches for T-Invariance Violation in Quantum Systems

for nuclear reactions that are two-body ones in the initial and final channels and which involve polarized particles, the T-null theorem stating the absence of vanishing observables in such reactions was proven in a number of studies by means of concepts of reaction \({\cal T}\) matrices that take into account general conservation laws along with T-invariance conditions in the “dynamically independent” approach. Not only does this approach focus on known mechanisms of such reactions, but it may also be applicable to their as-yet unknown mechanisms. By employing T-invariance conditions, the selection rules for specific mechanisms that make it possible to describe observables of a → b many-particle multistep nuclear reactions involving polarized particles are analyzed in the present study. It is shown that, in the differential cross sections for the initial nuclear reactions a → b and for \(\overline b \to \overline a \) reactions that are time-reversed with respect to them, the components characterized by specific P and T parities and related by T-invariance conditions are associated with unified mechanisms of their appearance and can be expressed in terms of unified scalar functions differing for a → b and \(\overline b \to \overline a \) reactions by the interchange of the channels and by the sign reversal for the momenta and spins of particles involved in these reactions. First, this permits selecting only one mechanism among all possible T-invariant mechanisms that describes simultaneously the features of the components considered for a → b and \(\overline b \to \overline a \) reactions and discarding all of the remaining mechanisms. Second, this enables one to obtain, in a number of cases, zero values for some components of the differential cross sections for the reactions in question. The latter constrains the applicability region of the aforementioned T-null theorem and makes it possible to use these components in the cross section for the initial reaction a → b to study the nature of T-noninvariant interactions.

Search for T-invariance violation in pd-scattering

Scattering of protons with transversal polarization Py p on deuterons with tensor polarization Pxz provides a null-test signal for time reversal invariance violating but P-parity conserving effects. The dedicated experiment will be done at COSY facility at proton beam energy 135 MeV using internal deuteron target. I give a brief review of results of theoretical calculations of the null-test observable within the spin-dependent Glauber theory at beam energies 100-1000 MeV considering phenomenological T-violating Pconserving NN-interactions.

Searching for T-invariance violation effects in spin observables of pd-scattering

Relationships imposed by the T-invariance on differential spin observables Ay, Py, Kxz, and Kzx of elastic pd-scattering are considered, and the degree to which these relationships are violated is estimated with allowance for the T-odd P-even interaction. The result is compared to a similar estimate for a null test experiment in which it is planned to measure the integral cross section of interaction between transversely polarized protons and aligned deuterons. The spin observables are calculated using a modification of the Glauber theory.

Spin observables in proton-deuteron scattering and T-invariance test

The total cross section for the interaction of transversely polarized protons ppy and deuterons that have a tensor polarization Pxz provides a null-test signal of T-invariance violation under the condition of P invariance. The relevant experiment is planned by the PAX Collaboration at the COSY accelerator with protons accelerated to the energy of 135 MeV. A modified Glauber theory is used here to calculate the differential spin observables Ay, Cy,y, Cxz,y, Cz,x, and Cx,z and the differential and total cross sections for proton-deuteron scattering in the case of T-even P-even proton-nucleon interactions. This makes it possible to estimate background conditions of the planned experiment.

Current status of research on T invariance in neutron-nuclear reactions

In this work, the current state of research on T invariance in neutron-nuclear reactions is considered. The promising character of investigations in this field related to possible enhancement of T-invariance violation in compound states of medium and heavy nuclei is underlined. Progress in preparation of experimental tests of T invariance using three-and five-vector correlations in cross sections of interaction of polarized neutrons with aligned nuclei is described in detail. T-invariance tests in reactions of radiative neutron capture and in coherent scattering of polarized neutrons on crystals are also considered.

The laser in the axial electric field as a tool to search for P-, T-invariance violation

We consider rotation of the polarization plane of the laser light when a gas laser is placed in a longitudinal electric field (10 kV cm−1). It is shown that residual anisotropy of the laser cavity 10−6 and the sensitivity to the angle of polarization plane rotation about 10−11–10−12 rad allow one to measure an electron EDM with the sensitivity about 10−30e cm.

Dissymmetry of magnetic crystals and its consequences

The term “dissymmetry” is proposed to be used in connection with the specific T-invariance violation at magnetic phase transitions. Well-known analogues of the similar dissymmetry with respect to the mirror reflection are biological molecules and realization of one enantiomorphous form at the growth of some crystals, the problems that are far from the solution at present time. For magnetic crystals, the problem is known for a long time, but till now a complete confusion exists in literature about the content of the matter. We have started systematic investigations in this direction by studying the mechanisms of the magnetic-induced anisotropy. This paper presents a brief summary of the obtained results.

Peculiarities in experiments searching for T-invariance violation in the free neutron decay

Possible sources of methodical errors at a level of 10 −4 in the measurement of the three-vector correlation coefficient D are investigated by the IAE research project.

Enhancement effects of the P-conserving T-invariance violation in neutron transmission.

The theoretical estimates of the $P$-conserving $T$-invariance violation in neutron transmission are reexamined. It is shown that the previously omitted factors of dynamical enhancement caused by the $T$-nonconserving interaction of the two closely lying resonances might sum up to an overall amplification of the effect by 3-5 orders of magnitude.

Can confinement ensure natural CP invariance of strong interactions?

P- and T-invariance violation in quantum chromodynamics due to the so-called θ-term is discussed. It is shown that irrespectively of how the confinement works there emerge observable P- and T-odd effects. The proof is based on the assumption that QCD resolves the U(1) problem, i.e., the mass of the singlet pseudoscalar meson does not vanish in the chiral limit. We suggest a modification of the axion scheme which restores the natural P and T invariance of the theory and cannot be ruled out experimentally.

Check of the T-invariance principle in 635 MeV pn-scattering

The “polarization-asymmetry” relation resulting from the T-invariance of strong interactions has been tested in a 635 MeV pn double-scattering experiment. No effects of T-invariance violation have been observed within the accuracy obtained of some percent in the angular range of (34–124)°. The T-odd scattering phase λ 1 has been obtained as λ 1=0.01 ± 0.02, which exceeds the accuracy of determining the λ 2 phase of pp-scattering at other energies.