arXiv subjects
Publications and source records attributed to L. B. Okun.
The dependence of the Z-resonance shape on the location of the threshold of the N\bar{N} production (N is the 4th generation neutrino) is analyzed. The bounds on the existence of 4th generation are derived from the comparison of the theoretical expression for the Z-lineshape with the experimental data. The 4th generation is excluded at 95% C. L. for m_N<46.7\pm 0.2 GeV.
Attempts to modify the standard expression for the phase in neutrino oscillations by an extra factor of two are based on misuse of quantum mechanics. Claims to present Bruno Pontecorvo and his coauthors as ``godfathers'' of this ``extra 2'' factor are easily disproved by unbiased reading their articles.
The present volume is the collection of contributions by friends of Holger Bech Nielsen for his 60th birthday. Contents: 1.Unified internal space of spins and charges (N. Mankoc Borstnik) 2.Semitopological Q-Rings (M. Axenides) 3.Non-local axial anomalies in the Standard model (D. Melikhov, B. Stech) 4.Could there be a fourth generation? (C.D. Froggatt) 5.Another complex Bateman equation (D.B. Fairlie) 6.Non-associative loops for Holger Bech Nielsen (P.H. Frampton) 7.Particles, fluids and vortices (J.W. van Holten) 8.Results on 2D current algebras (J.L. Petersen) 9.Phase transition in gauge theories and the Planck scale physics (L.V. Laperashvili and D.A. Ryzhikh) 10.Some remarks on the 'classical' large N limit (P. Olesen) 11.String theory and the size of hadrons (L. Susskind) 12.Relativity and $c/sqrt3$ (S.I. Blinnikov, L.B. Okun and M.I. Vysotsky) 13.Vortices (Jeff Greensite)
Classification of effects of violation of seven symmetries -- C, P, T, CP, PT, TC, and CPT -- is discussed. A graphic mnemonic scheme -- CPT-cube -- is suggested and illustrated by simple examples.
This paper consists of three separate articles on the number of fundamental dimensionful constants in physics. We started our debate in summer 1992 on the terrace of the famous CERN cafeteria. In the summer of 2001 we returned to the subject to find that our views still diverged and decided to explain our current positions. LBO develops the traditional approach with three constants, GV argues in favor of at most two (within superstring theory), while MJD advocates zero.
The predicted value of the higgs mass $m_H$ is analyzed assuming the existence of the fourth generation of leptons ($N, E$) and quarks ($U, D$). The steep and flat directions are found in the five-dimensional parameter space: $m_H$, $m_U$, $m_D$, $m_N$, $m_E$. The LEPTOP fit of the precision electroweak data is compatible (in particular) with $m_H \sim 300$ GeV, $m_N \sim 50$ GeV, $m_E \sim 100$ GeV, $m_U +m_D \sim 500$ GeV, and $|m_U -m_D| \sim 75$ GeV. The quality of fits drastically improves when the data on b- and c-quark asymmetries and new NuTeV data on deep inelastic scattering are ignored.
It is shown that additional chiral generations are not excluded by the latest electroweak precision data if one assumes that there is no mixing with the known three generations. In the case of ``heavy extra generations'', when all four new particles are heavier than $Z$ boson, quality of the fit for the one new generation is as good as for zero new generations (Standard Model). In the case of neutral leptons with masses around 50 GeV (``partially heavy extra generations'') the minimum of $χ^2$ is between one and two extra generations.
We define the critical coordinate velocity v_c. A particle moving radially in Schwarzschild background with this velocity, v_c= c/sqrt 3, is neither accelerated, nor decelerated if gravitational field is weak, r_g << r, where r_g is the gravitational radius, while r is the current one. We find that the numerical coincidence of v_c with velocity of sound in ultrarelativistic plasma, u_s, is accidental, since two velocities are different if the number of spatial dimensions is not equal to 3
Max Planck introduced four natural units: h, c, G, k. Only the first three of them retained their status, representing the so called cube of theories, after the theory of relativity and quantum mechanics were created and became the pillars of physics. This short note is a little pebble on the tombstone of Michael Samuilovich Marinov.
Recollections about a few episodes from the history of physics of vacuum, connected with the names of Pomeranchuk, Landau, Zeldovich, Sakharov and Kirzhnits. The text of the talk will be published in the Proceedings of the International Conference ``From the Smallest to the Largest Distances'', Tribute to Jean Tran-Thanh-Van, May 24-26, 2001 (``Surveys in High Energy Physics'', Taylor and Francis, 2002, v.16, No.3).
An extended text of the talk given at the conference ``2001: A Spacetime Odyssey'', to be published in the Proceedings of the Inaugural Conference of the Michigan Center for Theoretical Physics, University of Michigan, Ann Arbor, 21-25 May 2001, M.J. Duff and J.T. Liu eds., World Scientific, Singapore, 2002; and of Historical Lecture ``Vacuum as seen from Moscow'' at the CERN Summer School, 10 August, 2001. Contents: Introduction; Pomeranchuk on vacuum; Landau on parity, P, and combined parity, CP; Search and discovery of $K_L^0 \to π^+ π^-$; "Mirror world"; Zeldovich and cosmological term; QCD vacuum condensates; Sakharov and baryonic asymmetry of the universe, BAU; Kirzhnits and phase transitions; Vacuum domain walls; Monopoles, strings, instantons, and sphalerons; False vacuum; Inflation; Brane and Bulk; Acknowledgments; References.
Transparencies of the 18th Henry Primakoff lecture at the University of Pennsylvania, Philadelphia, USA, April 11, 2001 and of the Special lecture given at the 7th International Workshop on Topics in Astroparticle and Underground Physics, TAUP 2001, Laboratori Nazionali del Gran Sasso, Italy, September 9, 2001; to be published by Elsevier Nucl. Phys. B (Proceedings supplements). Various aspects of the concept of mass in modern physics are discussed: 1. Mass in Special Relativity, 2. Atoms in Static Gravity, 3. Photons in Static Gravity, 4. Misleading Terminology, 5. Unsolved Problems of mass.
Gauge invariance is the basis of the modern theory of electroweak and strong interactions (the so called Standard Model). The roots of gauge invariance go back to the year 1820 when electromagnetism was discovered and the first electrodynamic theory was proposed. Subsequent developments led to the discovery that different forms of the vector potential result in the same observable forces. The partial arbitrariness of the vector potential A brought forth various restrictions on it. div A = 0 was proposed by J. C. Maxwell; 4-div A = 0 was proposed L. V. Lorenz in the middle of 1860's . In most of the modern texts the latter condition is attributed to H. A. Lorentz, who half a century later was one of the key figures in the final formulation of classical electrodynamics. In 1926 a relativistic quantum-mechanical equation for charged spinless particles was formulated by E. Schrodinger, O. Klein, and V. Fock. The latter discovered that this equation is invariant with respect to multiplication of the wave function by a phase factor exp(ieX/hc) with the accompanying additions to the scalar potential of -dX/cdt and to the vector potential of grad X. In 1929 H. Weyl proclaimed this invariance as a general principle and called it Eichinvarianz in German and gauge invariance in English. The present era of non-abelian gauge theories started in 1954 with the paper by C. N. Yang and R. L. Mills.
The influence of static gravitational field on frequency, wave-length and velocity of photons and on the energy levels of atoms and nuclei is considered in the most elementary way. The interconnection between these phenomena is stressed.
In order to directly demonstrate that in static gravitational field the rate of clocks increases with their distance from the source a simple thought experiment is proposed.
The existence of extra chiral generations with all fermions heavier than $M_Z$ is strongly disfavored by the precision electroweak data. The exclusion of one additional generation of heavy fermions in SUSY extension of Standard Model is less forbidden if chargino and neutralino have low degenerate masses with $Δm \simeq 1$ GeV. However the data are fitted nicely even by a few extra generations, if one allows neutral leptons to have masses close to 50 GeV. Such heavy neutrino can be searched in the reaction $e^+ e^- \to N\bar{N}γ$ at LEP-200 with total final luminosity of $2600 pb^{-1}$.
The so-called equal velocity prescription for neutrino oscillations is forbidden kinematically.
Using the computer code CompHEP we estimate the number of events and the background, at LEP II and TESLA, for the reaction $e^+ e^- \to N\bar{N}γ$, where $N$ is a hypothetical Dirac neutrino with mass of the order of 50 GeV.