Status of experiments on<i>P</i>and<i>T</i>parity nonconservation at Novosibirsk

Барков, Л.М.; Zolotorev, M.; Melik-Pashaev, D. A.

doi:10.1070/qe1988v018n06abeh012271

Cited by 20 publications

(35 citation statements)

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“…• The e + e − → π + π − π + π − final state was studied by the experiments OLYA [64], ND [51], CMD [65], DM1 [66,67], DM2 [58,59,60], CMD-2 [61] and SND [62]. The experiments agree reasonably well within their quoted uncertainties (see Fig.…”

Section: Annihilation Datasupporting

confidence: 67%

“…• The cross sections of the six-pion final states 3π + 3π − and 2π + 2π − 2π 0 were measured by DM1 [70], CMD [65] and DM2 [71]. For the missing channel π + π − 4π 0 one can rely on isospin relations in order to estimate its contribution.…”

Section: Annihilation Datamentioning

confidence: 99%

“…• The e + e − → π + π − π + π − π 0 data are taken from M3N [56] and CMD [65]. It contains a contribution from the ηπ + π − channel with η → π + π − π 0 which has to be treated separately because the η decay violates isospin.…”

Section: Annihilation Datamentioning

confidence: 99%

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Confronting spectral functions from ee annihilation and $\tau$ decays: consequences for the muon magnetic moment

et al. 2003

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Vacuum polarization integrals involve the vector spectral functions which can be experimentally determined from two sources: (i) e + e − annihilation cross sections and (ii) hadronic τ decays. Recently results with comparable precision have become available from CMD-2 on one side, and ALEPH, CLEO and OPAL on the other. The comparison of the respective spectral functions involves a correction from isospin-breaking effects, which is evaluated. After the correction it is found that the dominant ππ spectral functions do not agree within experimental and theoretical uncertainties. Some disagreement is also found for the 4π spectral functions. The consequences of these discrepancies for vacuum polarization calculations are presented, with the emphasis on the muon anomalous magnetic moment. The work includes a complete re-evaluation of all exclusive cross sections, taking into account the most recent data that became available in particular from the Novosibirsk experiments and applying corrections for the missing radiative corrections. The values found for the lowest-order hadronic vacuum polarization contributions are a had,LO µ = (684.7 ± 6.0 exp ± 3.6 rad ) 10 −10 [e + e − −based] , (709.0 ± 5.1 exp ± 1.2 rad ± 2.8 SU (2) where the errors account for the hadronic, light-by-light scattering and electroweak contributions. We observe deviations with the recent BNL measurement at the 3.0 (e + e − ) and 0.9 (τ ) σ level, when adding experimental and theoretical errors in quadrature.

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Section: Annihilation Datasupporting

confidence: 67%

Section: Annihilation Datamentioning

confidence: 99%

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Confronting spectral functions from ee annihilation and $\tau$ decays: consequences for the muon magnetic moment

et al. 2003

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“…2) is the relaxation rate of atomic polarization. The zero-field resonances can be applied to low-field NMOR-magnetometry [3], with all of the advantages of the frequency-modulation technique as in the case of linear optical rotation [4,5].…”

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confidence: 99%

“…In order to avoid such problems, a light frequency modulation technique was introduced in Refs. [4,5] and was applied to measurements of linear magneto-optical rotation and parity-violating optical rotation. This technique allowed detection of optical rotation at the light modulation frequency without introducing additional optical elements (such as a Faraday modulator) between the polarizer and analyzer, considerably reducing spurious rotations.…”

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confidence: 99%

Nonlinear magneto-optical rotation with frequency-modulated light

et al. 2002

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A magnetometric technique is demonstrated that may be suitable for precision measurements of fields ranging from the sub-microgauss level to above the Earth field. It is based on resonant nonlinear magneto-optical rotation caused by atoms contained in a vapor cell with anti-relaxation wall coating. Linearly polarized, frequency-modulated laser light is used for optical pumping and probing. If the time-dependent optical rotation is measured at the first harmonic of the modulation frequency, ultra-narrow (∼ a few Hz) resonances are observed at near-zero magnetic fields, and at fields where the Larmor frequency coincides with half the light modulation frequency. Upon optimization, the sensitivity of the technique is expected to exceed 10 −11 G/ √ Hz.When light near-resonant to an atomic transition propagates through an atomic medium immersed in a magnetic field, the light polarization can be affected. For example, when a magnetic field is applied along the direction of light propagation, there is light-power-dependent rotation of the polarization plane known as nonlinear magneto-optical (Faraday) rotation (NMOR). Recently [1], we observed ultra-narrow (∼ 1 Hz) zero-field resonances in NMOR with rubidium atoms contained in vapor cells with high-quality anti-relaxation coating [2]. These resonances arise due to preservation of atomic polarization over thousands of collisions with the walls of the cell. The sensitivity of an NMOR-based magnetometer for sub-microgauss fields could, in principle, exceed 10 −11 G/ √ Hz [3], approaching the fundamental shot-noise limit (given the number of atoms in the cell and the polarization relaxation rate). In the present work, we describe a new technique that involves both inducing and measuring NMOR with a single frequencymodulated light beam. Additional ultra-narrow resonances are observed when the light modulation frequency coincides with twice the Larmor frequency, 2Ω L (and also with Ω L , etc.), the use of which can extend the dynamic range of an NMOR-based magnetometer to above the Earth field range (∼ 1 G) of interest in many applications.The high sensitivity of NMOR magnetometry is based in part on the ability of the polarimeter to measure small optical rotation angles. The sensitivity of polarimeters without modulation is limited by low-frequency noise. Therefore, the most successful polarimetric techniques always involve some type of fast modulation. In our previous work [1, 3], we used polarization-modulation polarimetry, where in addition to the vapor cell under investigation, a Faraday rotator is inserted between the crossed polarizer and analyzer. The Faraday rotator modulates the polarization direction at a frequency of ∼ 1 kHz, and the rotation angle is determined by measuring the first harmonic of the signal from a photodetector in the dark output of the analyzer. Such a method allows detection of signals at high frequencies, eliminating sensitivity to excess low-frequency noise. However, the polarization modulation technique has a number of shortcomings. Important...

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Fundamental Symmetry Aspects of Molecular Chirality

Barron

1991

New Developments in Molecular Chirality

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Status of experiments onPandTparity nonconservation at Novosibirsk

Cited by 20 publications

References 0 publications

Confronting spectral functions from ee annihilation and $\tau$ decays: consequences for the muon magnetic moment

Confronting spectral functions from ee annihilation and $\tau$ decays: consequences for the muon magnetic moment

Nonlinear magneto-optical rotation with frequency-modulated light

Fundamental Symmetry Aspects of Molecular Chirality

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