arXiv subjects

L. B. Okun

Publications and source records attributed to L. B. Okun.

51 records · Page 3Linked to original sources

arXiv1999

Extra quark-lepton generations and precision measurements

The existence of extra chiral generations with all fermions heavier than M_Z is strongly disfavoured by the precision electroweak data. However the data are fitted nicely even by a few extra generations, if one allows neutral leptons to have masses close to 50 GeV. The data allow inclusion of one additional generation of heavy fermions in SUSY extension of Standard Model if chargino and neutralino have masses close to 60 GeV with Δm =~ 1 GeV.

hep-ph↗

arXiv1999

On the Interpretation of the Redshift in a Static Gravitational Field

The classical phenomenon of the redshift of light in a static gravitational potential, usually called the gravitational redshift, is described in the literature essentially in two ways: on the one hand the phenomenon is explained through the behaviour of clocks which run the faster the higher they are located in the potential, whereas the energy and frequency of the propagating photon do not change with height. The light thus appears to be redshifted relative to the frequency of the clock. On the other hand the phenomenon is alternatively discussed (even in some authoritative texts) in terms of an energy loss of a photon as it overcomes the gravitational attraction of the massive body. This second approach operates with notions such as the "gravitational mass" or the "potential energy" of a photon and we assert that it is misleading. We do not claim to present any original ideas or to give a comprehensive review of the subject, our goal being essentially a pedagogical one.

physics.ed-ph↗

arXiv1999

Theory of Z boson decays

The precision data on Z boson decays from LEP-I and SLC colliders are compared with the predictions based on the Minimal Standard Theory. The Born approximation of the theory is based on three most accurately known observables: G_mu -- the four fermion coupling constant of muon decay, m_Z -- the mass of the Z boson, and alpha(m_Z) -- the value of the running fine structure constant at the scale of m_Z. The electroweak loop corrections are expressed, in addition, in terms of the masses of higgs, m_H, of the top and bottom quarks, m_t and m_b, and of the strong interaction constant alpha_s(m_Z). The main emphasis of the review is focused on the one-electroweak-loop approximation. Two electroweak loops have been calculated in the literature only partly. Possible manifestations of new physics are briefly discussed.

hep-ph↗

arXiv1997

On the search for muonic photons in neutrino experiments

Conserved muonic number may turn out to be a conserved muonic charge, coupled to muonic photons, gamma_mu. Muons and muonic neutrinos would emit gamma_mu's, which might be discovered by analysing the data from the past and future high energy neutrino experiments (like CHARM II, CCFR, CHORUS, NOMAD, etc.). There are two sources of gamma_mu's in these experiments: 1) internal bremsstrahlung in pion and kaon decays into mu and nu_mu, which provide neutrino beams; 2) external bremsstrahlung of muons in the shielding of the neutrino beam. In both cases the gamma_mu's would pass freely through the shielding and produce narrow muonic pairs in the neutrino detectors. These pairs could be distinguished from the trident events nu_mu + Z -> nu_mu + mu^+ + mu^- + Z by their kinematical properties: small p_t of the muon pair, small invariant mass, etc. All the above processes are quantitatively analysed in this paper.

hep-ph↗

arXiv1997

LEP, SLC and the Standard Model

A simple way of deriving and analyzing electroweak radiative corrections to the $Z$ boson decays is presented in the framework of the Standard Model. This paper is an updated and revised version of a plenary talk given at the Second Sakharov Conference; Lebedev Physical Institute, Moscow, May 20-24, 1996.

hep-ph↗

arXiv1997

Do muons oscillate ?

We develop a theory of the EPR-like effects due to neutrino oscillations in the $π\to μν$ decays. Its experimental implications are space-time correlations of neutrino and muon when they are both detected, while the pion decay point is not fixed. However, the more radical possibility of muon oscillations in experiments where only muons are detected (as it has been suggested in hep-ph/9509261), is ruled out. We start by discussing decays of monochromatic pions, and point out a few ``paradoxes''. Then we consider pion wave packets, solve the ``paradoxes'', and show that the formulas for $μnu$ correlations can be transformed into the usual expressions, describing neutrino oscillations, as soon as the pion decay point is fixed.

hep-ph↗

arXiv1996

LEP, Top and the Standard Model

A simple way of deriving and analyzing electroweak radiative corrections to the Z boson decays is presented in the framework of the Standard Model. The talk is based on a review article by the authors "Electroweak radiative corrections in Z decays" published in Uspekhi Fizicheskikh Nauk, 166 (1996) 539-574, in the May issue dedicated to 75th birthday o f A.D.Sakharov. The English translation of the article may be found on WWW (hep-ph/9606253).

hep-ph↗

arXiv1996

Fundamental Role of Experiments in High Energy Physics

An introductory talk at a Meeting on results and prospects of collaboration of Russian research organizations with European organization for nuclear research (CERN), which took place at the Ministry of science and technical policy of Russia on 8 July, 1996.

hep-ph↗

arXiv1996

Tests of CPT

A few remarks concerning theoretical suggestions and experimental tests of CPT during 1980's - 1990's. Is it worth to search for the particle-antiparticle mass differences in sectors other than $K^0\bar{K}^0$?

hep-ph↗

arXiv1996

Fundamental Constants of Nature

A brief review, from basic atomic constants to "Mendeleev Table" of leptons, quarks, fundamental bosons, and then to superunification of all forces and particles.

hep-ph↗

arXiv1996

Leptonic Photon and Light Element Abundancies

In the framework of a model, in which a single leptonic photon $γ_l$ has the same coupling to the doublets $μν_μ$ and $\barτ\barν_τ$, there is no cosmological bound on the strength of this coupling.

hep-ph↗

arXiv1995

How strong can the coupling of leptonic photons be?

Consequences of possible existence of leptonic photon are considered for a range of values of leptonic charge. In the case of a strong Coulomb-like leptonic repulsion between electrons the existence of ordinary condensed matter is impossible: antineutrinos cannot neutralize this destructive repulsion. The upper limit of leptonic charge is inferred from the Eötvös type experiments. If however there exist light stable scalar bosons with leptonic charge (e.g. singlet antisneutrinos) they may neutralize the electron repulsion. Possible experimental manifestations of such leptonic bosons in gases and condensed matter are briefly discussed.

hep-ph↗

arXiv1994

First Evidence for Electroweak Radiative Corrections from the New Precision Data

The analysis of the newest data on the leptonic $Z$-decays and $m_W$ appears to reveal the first manifestations of electroweak radiative corrections. In fact, these data differ, at the level of $2σ$, from their electroweak Born values, while they agree, to within $1σ$, with the theoretical values which take the electroweak radiative corrections into account. Previous data were within $1σ$ in agreement with both sets of values.

hep-ph↗

arXiv1994

The Values of $m_t$ and $\bar{α_s}$ Derived from the Non-Observation of Electroweak Radiative Corrections at LEP: Global Fit

A set of equations representing the $W/Z$ mass ratio and various observables of $Z$ decays in terms of $\barα\equivα(m_Z)$, $G_μ$, $m_Z$, $m_t$, $m_H$, $\barα_{s} \equivα_{s} (m_Z)$, $m_b$ and $m_τ$ (all other fermion masses being neglected) are compared with the latest data of the four LEP detectors, which at the level of one standard deviation coincide with their Born values. Our global fit gives: $m_t = 161^{+ 15 +16}_{-16 -22} \barα_{s} = 0.119 \pm 0.006 \pm 0.002$, where the central values correspond to $m_H = 300$ GeV, the first errors are statistical and the second ones represent shifts of the central values corresponding to $m_H = 1000$ GeV($+$) and 60 GeV($-$). The predicted mass of the top is smaller than in the recent fits by 4 GeV. The {\it predicted} values of $m_W/m_Z$ and the LEP observables, based on the fitted values of $m_t$ and $\barα_s$, show a weak dependence on $m_H$ and differ by several {\it predicted} standard deviations from the corresponding Born values. The uncertainties of the predicted values and their deviations from the corresponding Born values determine the experimental accuracy required to observe electroweak radiative corrections.

hep-ph↗

arXiv1993

Do Present LEP Data Provide Evidence for Electroweak Corrections?

The Born approximation, based on $\barα\equivα(m_Z)$ instead of $α$, reproduces all electroweak precision measurements within their $(1σ)$ accuracy. The low upper limits for the genuinely electroweak corrections constitute one of the major achievements of LEP. The astonishing smallness of these corrections results from the cancellation of a large positive contribution from the heavy top quark and large negative contributions from all other virtual particles. It is precisely the non-observation of electroweak radiative corrections that places stringent upper and lower limits on the top mass.

hep-ph↗