Roberto Mignani

More about Lorentz transformations and tachyons: answer to the comments by Ramachandran, Tagare and Kolaskar

I n a no t e (1), RAMACHA~DI~AN et al. h a v e c o m m e n t e d a b o u t a r ecen t , b r ie f l e t t e r b y 0LKHOVSKY a n d one of us (2), r ega rd ing L o r e n t z t r a n s f o r m a t i o n s (LT) a n d fas ter t han l i gh t -pa r t i c l e s (3.~). E v e n if t h e i r c o m m e n t s d id n o t a p p e a r to us to be v e r y p e r t i n e n t , we are grafefu l to t h e m for th i s occasion, since i t allows us to c lar i fy our p r e l i m i n a r y l e t t e r (2), wh ich r e m a i n e d indeed a t t h e surface of t h e p rob lems . I n pa r t i cu la r , we shal l show t h a t ou r p rev ious cons ide ra t ions can be founded m u c h b e t t e r t h a n in ref. (2).

MAGNETIC MONOPOLES AND TACHYONS

SummaryConnection between magnetic monopoles and faster-than-light particles is shown, in the framework of extended special-relativity theory, by generalizing the Maxwell equations to Superluminal sources.

Magnetic Monopoles and Tachyons in Special Relativity

Abstract The mere special relativity does not explicitly predict existence of (sub-luminal) monopoles, but on the contrary explicitly predicts existence of super-luminal (tachyon) monopoles, with magnetic charge about 100 times less than usually assumed. This fact is relevant also at the light of current experiments looking for magnetic poles.

Piezonuclear decay of thorium

We show that cavitation of a solution of thorium-228 in water induces its transformation at a rate 10000 times faster than the natural radioactive decay would do. This result agrees with the alteration of the secular equilibrium of thorium-234 obtained by a Russian team via explosion of titanium foils in water and solutions. These evidences further support some preliminary clues for the possibility of piezonuclear reactions (namely nuclear reactions induced by pressure waves) obtained in the last ten years.

Possible manifestations of the existence of a fourth-generation neutrino

A fourth generation of fermions predicted by the phenomenological heterotic string models can possess a new, strictly conserved charge. Among other things, this leads to the hypothesis of the existence of a fourth massive stable neutrino. A comparison of this hypothesis with the data obtained in the DAMA underground experiment to search for massive weakly-interacting cosmic particles with hidden mass and with the EGRET measurements of the >1 GeV galactic gamma-ray background gives a value m≈50 GeV for the possible mass of the fourth neutrino. It is shown that the hypothesis can be checked in accelerator experiments. The positron signal from annihilation of massive relic neutrinos in the galaxy is calculated. A search for this signal is is within the reach of planned cosmic-ray investigations.

Bose realization of a non-canonical Heisenberg algebra

The authors find out the Bose realization of a generalized Heisenberg algebra, in which the bracket of the annihilation and creation operators is proportional to a polynomial function of the number operator. The eigenvalues of the corresponding oscillator are derived in a special case. They stress also the connection between non-canonical commutation relations and q-algebras.

Quantum groups and Lie-admissible time evolution

The time evolution of operators for q-oscillators is derived for the first time by exploiting the connection between q-deformation algebras and Lie-admissible algebras.

ARE MUON NEUTRINOS FASTER-THAN-LIGHT PARTICLES?

Abstract Some papers have appeared recently which are noticeable since they call attention to interesting experimental results referring to the old-dated question whether neutrinos are superluminal (or not). They are complemented therefore, from the theoretical point of view, and some experimental predictions are added that could be tested, especially in connection with neutrino oscillations.

Broken Lorentz Invariance and Metric Description of Interactions in a Deformed Minkowski Space

We discuss the possible breakdown of Lorentz invariance—at distances greater than the Planck length—from both the theoretical and the phenomenological point of view. The theoretical tool to deal with such a problem is provided by a “deformation” of the Minkowski metric, with parameters dependent on the energy of the physical system considered. Such a deformed metric realizes, for any interaction, the “solidarity principle” between interactions and spacetime geometry (usually assumed for gravitation), according to which the peculiar features of every interaction determine—locally—its own spacetinie structure. The generalized theory of relativity, based on the locally deformed Minkowski spacetime, is called “deformed special relativity” (DSR). In the first part of the paper, we give the foundations and the basic laws of DSR. In the second part, we analyze some experimental data, which admit an interpretation in terms of the DSR formalism and are, therefore, candidates for displaying a breakdown of the Lorentz symmetry. They are (i) the superluminal propagation of evanescent electromagnetic waves in waveguides, (ii) the meanlife of the KS0, (iii) the Bose-Einstein correlation in pion production and (iv) the comparison of clock rates in the gravitational field of Earth. Such analysis provides us with the explicit forms of the related deformed metrics as functions of the energy, thus putting in evidence, in all four cases (and therefore for all four fundamental interactions), departures from the usual Minkowski metric. This preliminary evidence for a broken Lorentz invariance may be regarded as the signature of possible nonlocal effects involved in the processes examined. Moreover, the corresponding deformed metrics obtained by our analysis provide an effective dynamical description of the interactions (at least in the energy range considered).

Signature of relic heavy stable neutrinos in underground experiments

Considering heavy stable neutrinos of 4th generation we calculate the relic density of such neutrinos in the Universe. Taking into account the condensation of heavy neutrinos in the Galaxy and applying the results of calculations to experimental data from underground experiments on search for WIMPs in elastic neutral current scattering on nuclei we found an exclusion region of neutrino mass 60 GeV<m<290 GeV. The bounds obtained from present underground experiments while confirming the previous bounds derived from analysis of cosmic ray spectra are more relible ones. We discuss also the first indication of elastic scattering induced by WIMP in DAMA experiment finding a very narrow window of neutrino mass 45 GeV<m<50 GeV compatible with the possible signal rate in the detector.Considering heavy stable neutrinos of the 4th generation, we calculate the relic density of such neutrinos in the Universe. Taking into account the condensation of heavy neutrinos in the Galaxy and applying the results of calculations to experimental data from underground experiments on search for WIMPs in elastic neutral current scattering on nuclei, we find an exclusion region of neutrino mass 60 GeV<m< 290 GeV. The bounds obtained from the present underground experiments, while confirming the previous bounds derived from analysis of cosmic ray spectra, are more reliable. We also discuss the first indication of elastic scattering induced by WIMPs in the DAMA experiment, finding a very narrow window of neutrino mass 45 GeV<m<50 GeV compatible with the possible signal rate in the detector.