Tests Of Time Reversal Symmetry Research Articles

A direct test of T symmetry in the neutral K meson system at KLOE-2

This work presents prospects for conducting a novel direct test of time-reversal symmetry at the KLOE-2 experiment. Quantum entanglement of neutral K meson pairs uniquely available at KLOE-2 allows to probe the T symmetry directly and independently of CP violation. This is achieved by a comparison of probabilities for a transition and its inverse obtained through an exchange of initial and final states. Such transitions between flavor and CP-definite states of the neutral kaons are only connected by the T conjugation which ensures the CP-independence of the test. While a similar measurement was performed by the BaBar experiment with neutral B mesons, the KLOE-2 detector can test T-violation in the neutral kaons system. Such a test requires i.a. reconstruction of the KL → 3π0 decay accompanied by Ks → π±ℓ∓ν with good timing information. Therefore a new reconstruction method for the KL → 3π0 decay is also presented which is capable of reconstructing this process with decay time resolution of O(1τS).

Study of the $K_{\rm S}K_{\rm L}\to \pi \ell \nu 3\pi ^0$ Process for Time Reversal Symmetry Test at KLOE-2

This work presents prospects for conducting a novel direct test of time-reversal symmetry at the KLOE-2 experiment. Quantum entanglement of neutral K meson pairs uniquely available at KLOE-2 allows to probe directly the time-reversal symmetry (T) independently of CP violation. This is achieved by a comparison of probabilities for a transition between flavour and CP-definite states and its inverse obtained through exchange of initial and final states. As such a test requires the reconstruction of the $K_L\to 3\pi^0$ decay accompanied by $K_S\to\pi^{\pm}\ell^{\mp}\nu$ with good timing information, a new reconstruction method for this process is also presented which is capable of reconstructing the $K_L\to 3\pi^0$ decay with decay time resolution of O(1$\tau_S$).

T-Violation experiment at TRIUMF-ISAC using polarized8Li

Motivated by a search for a new physics beyond the standard model, the MTV experiment (Mott Polarimetry for T-Violation Experiment) is intended to achieve the highest precision test of time-reversal symmetry in polarized nuclear beta decay by measuring a triple correlation (the R -correlation). The first physics run of the MTV experiment was performed in 2010 at TRIUMF-ISAC. This paper gives preliminary results and describes the next generation setup, which involves a cylindrical drift chamber.

The MTV experiment: a test of time reversal symmetry using polarized 8Li

The MTV (Mott Polarimetry for T-Violation Experiment) experiment at TRIUMF-ISAC (Isotope Separator and ACcelerator), which aims to achieve the highest precision test of time reversal symmetry in polarized nuclear beta decay by measuring a triple correlation (R-correlation), is motivated by the search for a new physics beyond the Standard Model. In this experiment, the existence of non-zero transverse electron polarization is examined utilizing the analyzing power of Mott scattering from a thin metal foil. Backward scattering electron tracks are measured using a multi-wire drift chamber for the first time. The MTV experiment was commissioned at ISAC in 2009 using an 80%polarized 8Li beam at 107 pps, resulting in 0.1%statistical precision on the R-parameter in the first physics run performed in 2010. Next generation cylindrical drift chamber (CDC) is now being installed for the future run.

TIME REVERSAL SYMMETRY

Time reversal independent of the CP symmetry is reviewed. Experimental tests of time reversal symmetry are given. Basic theories of time reversal invariance are provided.

Direct test of time reversal symmetry in the entangled neutral kaon system at a ϕ-factory

We present a novel method to perform a direct T (time reversal) symmetry test in the neutral kaon system, independent of any CP and/or CPT symmetry tests. This is based on the comparison of suitable transition probabilities, where the required interchange of in ↔ out states for a given process is obtained exploiting the Einstein–Podolski–Rosen correlations of neutral kaon pairs produced at a ϕ-factory. In the time distribution between the two decays, we compare a reference transition like the one defined by the time-ordered decays (ℓ−,ππ) with the T-conjugated one defined by (3π0,ℓ+). With the use of this and other T-conjugated comparisons, the KLOE-2 experiment at DAΦNE could make a statistically significant test.

Test of Time Reversal Symmetry using polarized 8Li at TRIUMF-ISAC

A new experimental project called MTV (Mott Polarimetry for T-Violation Experiment), is running at TRIUMF. It aims to achieve the highest precision test of time reversal symmetry in polarized nuclear beta decay by measuring a triple correlation (R-correlation), motivated to search a new physics beyond the standard model. It is because the CKM predicts negligible effects on the u-d quark system. In this experiment, the existence of non-zero transverse electron polarization is examined utilizing the analyzing power of Mott scattering from a thin metal foil. Backward scattering electron tracks are measured using a multi-wire drift chamber event-by-event for the first time. The tracking device eliminates the largest systematic effect, which has been limiting the sensitivity of previous studies. The MTV experiment was commissioned at TRIUMF-ISAC in 2009 using an 80% polarized 8Li beam at 10 Mpps resulting in 3.6% precision on the R-parameter, after performing a feasibility test at KEK-TRIAC in 2008 using an 8% polarized beam at 100 kpps yielding 41% statistical precision. In 2010, a physics production run is scheduled, aiming to reach below 0.1% precision. In this document, the preparation status for the 2010 run and results from the commissioning run are described.

Electron Transverse Polarimeter for the MTV experiment at TRIUMF

A new experimental project called MTV(Mott Polarimetry for T-Violation Experiment)-S1183 has started at TRIUMF, aiming to achieve the highest precision test of time reversal symmetry in polarized nuclear beta decay. In this experiment, existence of T-violating transverse polarization of electrons emitted from polarized nuclei is examined, using a multi-wire drift chamber (MWDC) as an electron tracking detector in order to measure Mott scattering asymmetries. In this paper, technical aspects of the electron polarimetry are described. The Mott polarimeter, MWDC, consists of six sense layers. In order to improve the real backward scattering event purity, a new intelligent triggering system using FPGA module to perform on-line hit pattern recognition was developed. The new triggering system was installed for the first commissioning experiment in November 2009 at TRIUMF-ISAC. In addition to the triggering system, a new buffering DAQ system was also developed in order to achieve the needed high triggering rate at ISAC. Details of their performance are also described.

Tests of time reversal symmetry in radioactive nuclei

An effective method to test time reversal invariance in the non-strange sector is to measure parity and time reversal violating (T,P-odd) electromagnetic moments, such as the static electric dipole moment. Parity and time reversal violating components in the nuclear force may produce P,T-odd moments in nuclei which, in turn, induce such moments in atoms. After a short introduction, we discuss the possibility that in some reflection-asymmetric heavy radioactive nuclei these moments are enhanced by several orders of magnitude. This opens the opportunity to improve significantly the limits on time reversal invariance. Some present and future experiments, which will test this idea, are mentioned. Recent theoretical results are briefly discussed.

Demonstration of a Two Species Noble Gas Maser.

We have demonstrated the first two species maser. Ensembles of ${}^{3}\mathrm{He}$ and ${}^{129}\mathrm{Xe}$ gas, co-located in a double-chamber glass cell, performed simultaneous maser oscillations on their nuclear spin- $\frac{1}{2}$ Zeeman transitions. This new device may be used for experiments requiring precision magnetometry combined with frequency measurement of a second free-running species operating in the same volume. For example, the ${}^{3}\mathrm{He}$ maser may serve as a magnetometer, while the ${}^{129}\mathrm{Xe}$ maser may be used to search for a permanent electric dipole moment of the ${}^{129}\mathrm{Xe}$ atom as a test of time reversal symmetry.

Effective T-odd P-even hadronic interactions from quark models.

Tests of time-reversal symmetry at low and medium energies may be analyzed in the framework of effective hadronic interactions. Here, we consider the quark structure of hadrons to make a connection to the more fundamental degrees of freedom. It turns out that for {ital P}-even {ital T}-odd interactions hadronic matrix elements evaluated in terms of quark models give rise to factors of 2 to 5. Also, it is possible to relate the strength of the anomalous part of the effective {rho}-type {ital T}-odd {ital P}-even tensor coupling to quark structure effects. {copyright} {ital 1996 The American Physical Society.}

Limit on the electric-dipole moment of 199Hg using synchronous optical pumping.

Synchronously driven optically pumped atomic oscillators have been used to measure the electric-dipole moment of $^{199}\mathrm{Hg}$ as a test of time-reversal symmetry. Our result, d${(}^{199}$Hg)8.7\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}28}$e cm, is the smallest experimental limit on the size of an electric-dipole moment and sets stringent bounds on several sources of time-reversal symmetry violation in atomic systems. This article describes the details of the experimental apparatus, the measurement procedure, and the implications of the result for CP violation in elementary particle interactions.

Test of time-reversal symmetry in the proton-deuteron system

Internal target experiments with high-quality proton beams allow for a new class of experiments providing null tests of time-reversal symmetry in forward scattering. This could yield more stringent limits on T-odd P-even observables. An excellent candidate for such experiments is the proton-deuteron system. This system is analyzed in terms of effective T-violating P-conserving nucleon-nucleon interactions and bounds on coupling strengths that might be expected are given.

Model analysis of time-reversal symmetry test in the 57Fe gamma -transition experiment.

The CALTECH \ensuremath{\gamma}-transition experiment testing time-reversal symmetry via the E2/M1 multipole mixing ratio of the 122-keV \ensuremath{\gamma} line in $^{57}\mathrm{Fe}$ has already been performed in 1977. Extending an earlier analysis in terms of an effective one-body potential, this experiment is now analyzed in terms of effective one-boson-exchange T-odd P-even nucleon-nucleon potentials. Within the model space considered for the $^{57}\mathrm{Fe}$ nucleus no contribution from isovector \ensuremath{\rho}-type exchange is possible. The bound on the coupling strength ${\mathrm{\ensuremath{\varphi}}}_{\mathit{A}}$ from effective short-range axial-vector-type exchange induced by the experimental bound on sin\ensuremath{\eta} leads to ${\mathrm{\ensuremath{\varphi}}}_{\mathit{A}}$\ensuremath{\le}${10}^{\mathrm{\ensuremath{-}}2}$.

Tenfold improvement of limits on T violation in thallium fluoride.

We have made a stringent test of time-reversal symmetry using nuclear-spin resonance in a rotationally cold, supersonic beam of thallium fluoride molecules. We searched for a shift of the 120-kHz thallium spin resonance when a 29.5 kV/cm external electric field was reversed relative to the nuclear spin and found this to be (1.4\ifmmode\pm\else\textpm\fi{}2.4)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}4}$ Hz. This is a tenfold improvement over our previous measurement in thallium fluoride. The derived constraints on the proton and electron electric dipole moments and on T violation in both strong and weak interactions are correspondingly improved.

Detailed-balance test of time-reversal symmetry for a pair of close-lying resonances.

We present a thorough analysis of tests of detailed balance involving a pair of interfering resonances. For two close-lying (overlapping) compound-nucleus resonances in a regime where the average resonance spacing is much larger than the average resonance width, we find enhancement factors as large as ${10}^{3}$--${10}^{4}$.

Theory of time-reversal symmetry breaking in compound-nucleus reactions

The interpretation of experimental tests of time-reversal symmetry in compound-nucleus reactions requires the theoretical calculation of a correlation coefficientR. We evaluateR in the framework of a statistical model, and relate it to the observables.

Tests of time-reversal symmetry in compound-nucleus reactions.

Using a generating function with both commuting and anticommuting variables, we calculate perturbatively the violation of the principle of detailed balance due to breaking of time-reversal symmetry in a statistical nuclear reaction. We apply this result to the best data and establish upper bounds for the strength of, and the spreading width associated with, the symmetry-breaking part of the Hamiltonian. We argue that the spreading width is the fundamental parameter of the theory. A way of further improving the upper bounds is suggested.