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A proposed experimentum crucis for the orthopositronium lifetime anomalies.

Expansion of the Standard Model (SM) for the quantitative description of the orthopositronium lifetime anomalies allows formulation of additional experimental tests of supersymmetry in the final state of the positron beta-decay of nuclei such as [sup.22]Na, [sup.68]Ga, and resolution of the results of the last Michigan experiment (2003).


In 2003, at the University of Michigan (Ann Arbor), a measurement of the o-Ps annihilation rate was carried out, and the researchers reported complete agreement between the experimental value, [[lambda].sub.T] = 7.0404(10)(8) [[micro]s.sup.-1], and the value calculated in the frame of QED, [[lambda].sub.T(theor)] = 7.039979(11)[[micro]s.sup.-1] [1]. These measurements were performed by a different technique, namely, a dc electric field of 7 kV/cm was introduced into the measurement cell. For this reason, and since they disregarded the "isotope anomaly" of o-Ps in gaseous neon in "resonance conditions" [2, 3], authors [1] could not include the additional action of the electric field on the observed o-Ps self-annihilation rate [[lambda].sub.Y(exp)] [3], notwithstanding the provisions they undertook to ensure complete o-Ps thermalization. The additional action of the electric field E~7kV/cm oriented parallel to the force of gravity should suppress the excess [DELTA][[lambda].sub.T][??]0.19 o 0.14% over the calculated value [[lambda].sub.T(theor)], which had been reported earlier by the Michigan group and referred to quantitatively as the macroscopic quantum effect (the "[[lambda].sub.T]-anomaly" [3]) *.

This is why rejection [1] of the conclusions drawn from the earlier high-precision [[lambda].sub.T] measurements does not appear unambiguous.

The uncertainty we are presently witnessing can be resolved only by performing a program of additional measurements.

Consider the scheme of a Gedanken experiment for a measuring cell filled with a gas (Fig. 1).


Could one substantiate a program of comparative measurements which would yield as a final result the doubling of the parameter V to be measured with the external dc electric field orientation changed from horizontal to vertical? This would be certainly impossible within the SM. An analysis of the o-Ps anomalies within the concept of spontaneously broken complete relativity opens up such a possibility; indeed, restoration of the symmetry under discussion "should be accompanied by doubling of the space-time dimension" [4].

The uniqueness of orthopositronium dynamics (virtual single-quantum (!) annihilation, CP-invariance) make it an intriguing probe to double the space-time (see [5]).

Consider in this connection again the standard experimental technique used to measure positron/orthopositronium annihilation lifetime spectra.

Figure 2 presents a block diagram of a fast-slow lifetime spectrometer of delayed [[gamma].sub.n] - [[gamma].sub.a] coincidences.


Recording of real coincidences (in the start-stop arrangement) with a time resolution of 1.7 x [10.sup.-9] s [2] between the signal produced by a nuclear [[gamma].sub.n] quantum of energy [??] 1.28 MeV ("start") with the signal generated by the detected [[gamma].sub.a] annihilation quantum of energy [??]0.34 o 0.51MeV ("stop", corresponding, accordingly, to 3[gamma] and 2[gamma]-annihilation) is accompanied by the energy (amplitude) discrimination in the slow ("side") coincidence channels (with a resolution [delta][[tau].sub.s] ~ [10.sup.-6] s between the corresponding signals from the last-but-one dynodes of the lifetime PM tubes, an approach that cuts efficiently random coincidence noise.

After subtraction of the random coincidence background, the positron annihilation lifetime spectra of inert gases would represent the sums of exponentials with characteristic annihilation rate constants [[lambda].sub.i]


where [[lambda].sub.0] and [I.sub.0] are, respectively, the rate and intensity of two-quantum annihilation of the para-positronium component (p-Ps), [[lambda].sup.1] and [I.sup.1] are the components of two-quantum annihilation of the quasi-free positrons that have not formed positronium (with so-called "shoulder" peculiarity [5]), and [[lambda].sup.2] and [I.sup.2] are those of three-quantum annihilation of the orthopositronium component.

Experimental bounds accumulated in the two decades of intense studies of the orthopositronium problem lead one to the conclusion that the additional single-quantum mode of orthopositronium annihilation involves not a photon but rather a notoph ([lambda][degrees] is a zero-mass, zero-helicity particle which is complementary in properties to the photon) [7] and two mirror photons [gamma]' with a negative total energy of 3.6 x [10.sup.-4] eV [3, 5]:


This was how the broadening of the framework in which the nature of the o-Ps anomalies could be analyzed (from QED to SQED) and the phenomenology of the mechanism of energy and momentum deficit compensation in a single-quantum mode were first formulated [7].

Treated from the SM standpoint, however, detection of a quantum of energy 1.022MeV in the "stop" channel of the fast-slow coincidences is forbidden (see the "lower" and "upper" detection thresholds of ~0.34 o 0.51 MeV, respectively, in Fig. 2).

We now come back to the principal question of how the additional realization of supersymmetry would be established in the experiment.

Detection of a single-notoph o-Ps annihilation mode should also be accompanied by observation of an energy deficit in the "stop" channel of the lifetime spectrometer: indeed, single-notoph annihilation is identified in the scintillator by the Compton-scattered electron e, which is bound in the long-range atom "shell" in a "pair" e[bar.e] with the "electronic hole" [bar.e] (negative mass) in the "C-field/mirror Universe" structure. Half of the notoph energy, ~0.51 MeV, is transferred to the e hole ([bar.e]) and, thus, "disappears" (anti-Compton scattering). As a result, the additional single-notoph mode is detected by the lifetime spectrometer in the "stop" channel by Compton scattering of an electron e of energy [less than or equal to] 0.51 eV.

The experiment is in agreement with the phenomenology proposed for quantitative description of the o-Ps anomalies provided we assume that the additional single-notoph annihilation mode contributes to the instantaneous coincidence peak [5]. This means that one half of the intensity of the long-lived lifetime spectral component obtained under "resonance conditions" for neon of natural isotope abundance ([I.sub.2]) transfers to the t ~ 0 region. An electric field of 7 kV/cm applied parallel to the force of gravity should suppress the additional mode and double the orthopositronium component (2[I.sub.2]). Accordingly, in the Michigan experiment (non-resonance conditions) an electric field oriented along the force of gravity would bring about complete agreement between [[lambda].sub.T(exp)] with the QED-calculated value [[lambda].sub.T(theor)]; and the disagreement of about [DELTA][[lambda].sup.T]/[[lambda].sub.T] [??] 0.19 o 0.14% found previously (in experiments without electric field) should again appear after the action of the electric field has been neutralized (by applying it perpendicular to the force of gravity) [3].

The term "anti-Compton scattering" has been borrowed from J. L. Synge [8]; it appears appropriate to cite here an excerpt from the abstract of this paper written by a celebrated proponent of the theory of relativity:
 "The purpose of this paper is to answer the following
 question in terms of concepts of classical relativistic
 mechanics: How is Compton scattering altered if we
 replace the photon by a particle of zero rest mass
 and negative energy, and apply the conservation of 4-momentum?
 [...] Since particles with negative energies
 are not accepted in modern physics, it is perhaps
 best to regard this work as a kinematical exercise in
 Minkowskian geometry, worth recording because the
 results are not obvious".

Observation of orthopositronium anomalies gives one physical grounds to broaden the present-day SM. It now appears appropriate to analyze "anti-Compton scattering" in connection with the detection of notoph in the proposed program of additional measurements, which aim at proving the existence of a connection between gravity and electromagnetism [3].

We may add that the concept of the supersymmetric version of a spin-1/2 quasi-particle and a hole as supersymmetric partners has been discussed in the literature [9].

To sum up: one should carry out additional measurements because the result, inconceivable in the frame of the SM, becomes an expected result in the program of experimentum crucis (Fig. 3).


A positive result of this crucial experiment would mean the birth of new physics that would be complementary to the Standard Model.

* Here and so forth the sign o means that the values were obtained in the gas and vacuum experiments respectively.


[1.] Vallery R. S., Gidley D.W. and Zitzewitz P.W. Resolution of orthopositronium-lifetime puzzle. Phys. Rev. Lett., 2003, v. 90(20), 203402 (1-4).

[2.] Levin B. M., Kochenda L. M., Markov A. A. and Shantarovich V. P. Time spectra of annihilation of positron ([sup.22]Na) in gaseous neon of various isotopic compositions. Sov. J. Nucl. Phys., 1987, v. 45(6), 1119-1120.

[3.] Kotov B. A., Levin B. M. and Sokolov V. I. Orthopositronium: on the possible relation of gravity to electricity. Preprint-1784, A. F. Ioffe Physical Technical Institute of Russian Academy of Sciences. St.-Petersburg, 2005; arXiv: quant-ph/0604171.

[4.] Andreev A. F. Spontaneously broken complete relativity. JETF Lett., 1982, v. 36(3), 100.

[5.] Levin B. M. Orthopositronium: annihilation of positron in gaseous neon. arXiv: quant-ph/0303166.

[6.] Ogievetskii V. I. and Polubarinov I.V. Notoph and its possible interactions. Sov. J. Nucl. Res., 1966, v. 4(1), 156.

[7.] Levin B. M. On the kinematics of one-photon annihilation of orthopositronium. Phys. At. Nucl., 1995, v. 58 (2). 332.

[8.] Synge J. L. Anti-Compton scattering. Proc. Roy. Ir. Acad., 1974, v.A74 (9), 67.

[9.] Lee C. J. Spin-1/2 particle and hole as supersymmetry partners. Phys. Rev. A, 1994, v.50, R4 (4-6).

Boris M. Levin


Submitted on January 24, 2007 Accepted on January 30, 2007
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Author:Levin, Boris M.
Publication:Progress in Physics
Geographic Code:1U3MI
Date:Apr 1, 2007
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