New Precision Determination of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>Mass from Pionic X Rays

Jeckelmann, B.; Nakada, T.; Beer, W.; G, de Chambrier; Elsenhans, O.; Kl, Giovanetti; Pf, Goudsmit; Hj, Leisi; Rüetschi, A.; Piller, O.; Schwitz, W.

doi:10.1103/physrevlett.56.1444

Cited by 42 publications

(15 citation statements)

References 11 publications

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“…#6 Furthermore, in many laboratory experiments measuring direct kinematical limits, the measured 4-impulse squared of neutrinos appears to be negative. The experimental data involving p 2 < 0 for electron [c)] and muon [a) and b)] neutrinos has been deduced out from: a) observation of pion decay, [28] b) precision measurements of π − mass, [29] c) kinematical analysis of tritium beta-decay. [30−35] Let us mention the experimental results for m 2 (eV) 2 found in c): (−65±85±65) [30] ; (−24±48±61) [31] ; (−147±68±41) [32] ; (−39±34±15) [33] ; (−72±41±30) [34] .…”

Section: Duality Between Momentum and Velocitymentioning

confidence: 99%

Slower-Than-Light Spin-$\frac{1}{2}$ Particles Endowed with Negative Mass Squared

Salesi

1997

Int. J. Mod. Phys. A

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Extending in a straightforward way the standard Dirac theory, we study a quantum mechanical wave-equation describing free spinning particles -which we propose to call Pseudotachyons (PT's)-which behave like tachyons in the momentum space (p 2 = −m 2 ), but like subluminal particles (v < c) in the ordinary space. This is allowed since, as it happens in every quantum theory for spin-1 2 particles, the momentum operator, −i∇, (that is conserved) and the velocity operator α (that is not) are independent operators, which refer to independent quantities: p = m v. As a consequence, at variance with ordinary Dirac particles, for PT's the average velocity v ≡ ψ † αψ / ψ † ψ is not equal to the classical velocity v cl = p/ε, but actually to the velocity "dual" of v cl : εp/p 2 . Being reciprocal of |v cl |, the speed of PT's is therefore smaller than the speed of light. Since a lot of experimental data seems to involve a negative mass squared for neutrinos, we suggest that these particles might be PT's, travelling, because of their very small mass, at subluminal speeds very close to c. The present theory is shown to be separately invariant under the C, P , T transformations; the covariance under Lorentz transformations is also proved. Furthermore, we derive the kinematical constraints linking 4-impulse, 4-velocity and 4-polarization of free PT's.

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Section: Duality Between Momentum and Velocitymentioning

confidence: 99%

Slower-Than-Light Spin-$\frac{1}{2}$ Particles Endowed with Negative Mass Squared

Salesi

1997

Int. J. Mod. Phys. A

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“…The determination of the pionic cascade in Mg, on the other hand, may help to eliminate the largest uncertainty in the determination of the pion mass [12] from the energy of the ~z(4f--+ 3d) transition, the electron-screening correction, which is caused by insufficient knowledge about the electrons present in the moment of the transition.…”

Section: Introductionmentioning

confidence: 99%

Absolute pionic x-ray intensities in Mg and Fe

Hartmann

Daniel

Neumann

et al. 1991

Z. Physik A - Hadrons and Nuclei

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Absolute pionic x-ray intensities have been measured for Mg and Fe. The accuracy achieved was 2% of the line intensity for the most prominent transitions. In the Balmer series of Mg and the Paschen series of Fe the crossover transitions were found to be even more attenuated than the transitions between circular states, as deduced, for example, by comparison with muonic atoms; no crossover transitions were observed in the Fe Balmer series. According to cascade calculations based on the experimental intensities more than half of the pions are absorbed in Fe already from levels with principal quantum number n > 17 by strong interaction.

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“…Five recent experiments [4,5,6,7,8] have measured the squared mass of the electron neutrino to be negative, with the mean more than two standard deviations from zero. Measurements of the squared mass of the muon neutrino over the past decade [9,10,11,12,13] have similarly produced negative values, with the latest being five standard deviations from zero. The situation in the muonic case has been altered very recently by a remeasurement of a crucial pionic x-ray intensity, which allows a new solution for the pion mass that yields a muon-neutrino squared mass compatible with zero [14].…”

Section: Introductionmentioning

confidence: 99%