Neutron–antineutron oscillation and discrete symmetries

2018 ◽  
Vol 33 (31) ◽  
pp. 1844016 ◽  
Author(s):  
Zurab Berezhiani ◽  
Arkady Vainshtein
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Text Classification ◽  
Discrete Symmetries ◽  
Rotational Invariance ◽  
Baryon Charge ◽  
Free Particles ◽  
Definition Of ◽  
Charge Formula

We analyze status of [Formula: see text], [Formula: see text] and [Formula: see text] discrete symmetries in application to neutron–antineutron transitions breaking conservation of baryon charge [Formula: see text] by two units. At the level of free particles, all these symmetries are preserved. This includes [Formula: see text] reflection in spite of the opposite internal parities usually ascribed to neutron and antineutron. Explanation, which goes back to the 1937 papers by Majorana and Racah, is based on a definition of parity satisfying [Formula: see text], instead of [Formula: see text], and ascribing [Formula: see text] to both, neutron and antineutron. We apply this to [Formula: see text], [Formula: see text] and [Formula: see text] classification of six-quark operators with [Formula: see text]. It allows to specify operators contributing to neutron–antineutron oscillations. Remaining operators contribute to other [Formula: see text] processes and, in particular, to nuclei instability. We also show that presence of external magnetic field does not induce any new operator mixing the neutron and antineutron provided that rotational invariance is not broken.

scholarly journals DECAY OF SPIN-ONE PARTICLE INTO TWO PHOTONS IN PRESENCE OF UNIFORM EXTERNAL MAGNETIC FIELD

2007 ◽  
Vol 22 (04) ◽  
pp. 707-720 ◽  
Author(s):  
DILIP ANGOM ◽  
KAUSHIK BHATTACHARYA ◽  
SAURABH D. RINDANI
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Elementary Particles ◽  
Decay Process ◽  
Rotational Invariance ◽  
Atomic Transitions ◽  
Uniform External Magnetic Field ◽  
Cp Invariance

Yang's theorem states that an initial J = 1 state cannot decay into two photons. Because of this result some reactions relating to elementary particles or atomic transitions can be ruled out. The theorem is not valid in the presence of background electric or magnetic fields. In this work we show that the decay of a J = 1 particle into two photons is permitted by the Bose symmetry and rotational invariance when the background of the decay process is not pure vacuum but contains an external classical magnetic/electric field. We also discuss constraints on these amplitudes from the CP invariance.

scholarly journals External Magnetic Field Measurements in UME Kibble Balance

ACTA IMEKO ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 33
Author(s):  
Haci Ahmedov ◽  
Beste Korutlu ◽  
Lev Dorosinskiy ◽  
Recep Orhan ◽  
Ozlen Tuncel
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Vertical Direction ◽  
Field Measurements ◽  
Magnetic Flux Density ◽  
National Metrology Institute ◽  
Mass Unit ◽  
Long Term Stability ◽  
Faraday’S Law ◽  
Definition Of

The new definition of kilogram in terms of the fixed value of Planck constant ensures the long-term stability of SI mass unit and enables traceability from more than one source. Kibble balance experiments offer an effective primary realization method for the new definition of kilogram. Kibble Balance apparatus operating at National Metrology Institute of Turkey is designed with a stationary coil and an oscillating magnet. In contradistinction to traditional moving coil Kibble balance experiments, external magnetic field brings an asymmetry between the Ampere’s law of force and the Faraday’s law of induction in moving magnet experiments. In this paper, we develop a method based on the external magnetic flux density difference measurements in vertical direction to take into account the effect of the external magnetic field on the realization of kilogram. The proposed model in this approach fits well with the data such that the kilogram realization requirement is met within the accuracy of the measuring instrument.

scholarly journals The effective susceptibility of a paramagnetic powder

1941 ◽  
Vol 178 (972) ◽  
pp. 86-92 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Material ◽  
External Magnetic Field ◽  
Curie Temperature ◽  
Temperature Scale ◽  
Preceding Paper ◽  
Theoretical Expression ◽  
Demagnetizing Field ◽  
Definition Of ◽  
Packed Powder

The effective susceptibility (that is, the magnetic moment divided by the external magnetic field) of a paramagnetic powder loosely packed into an ellipsoidal container has been measured against the vapour pressure of liquid helium, and hence, using the results of the preceding paper, against the susceptibility of the compact salt. The definition of the ‘Curie’ temperature scale is based on the latter, and it is found that the correction to be applied in calculating the Curie temperature from the effective susceptibility of the powder agrees with that given by a theoretical expression derived from Breit’s calculation of the demagnetizing field of a powder. This is of importance both in experiments using a loosely packed powder and in experiments using a paramagnetic powder mixed with a non-magnetic material.

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