108 research outputs found
On the extra factor of two in the phase of neutrino oscillations
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.Comment: 5 pages, two sentences at the end of the paper are deleted and two
are adde
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 E\"{o}tv\"os 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.Comment: 13 pages in standard LaTe
Macroscopic Strings and "Quirks" at Colliders
We consider extensions of the standard model containing additional heavy
particles ("quirks") charged under a new unbroken non-abelian gauge group as
well as the standard model. We assume that the quirk mass m is in the
phenomenologically interesting range 100 GeV--TeV, and that the new gauge group
gets strong at a scale Lambda < m. In this case breaking of strings is
exponentially suppressed, and quirk production results in strings that are long
compared to 1/Lambda. The existence of these long stable strings leads to
highly exotic events at colliders. For 100 eV < Lambda < keV the strings are
macroscopic, giving rise to events with two separated quirk tracks with
measurable curvature toward each other due to the string interaction. For keV <
Lambda < MeV the typical strings are mesoscopic: too small to resolve in the
detector, but large compared to atomic scales. In this case, the bound state
appears as a single particle, but its mass is the invariant mass of a quirk
pair, which has an event-by-event distribution. For MeV < Lambda < m the
strings are microscopic, and the quirks annihilate promptly within the
detector. For colored quirks, this can lead to hadronic fireball events with
10^3 hadrons with energy of order GeV emitted in conjunction with hard decay
products from the final annihilation.Comment: Added discussion of photon-jet decay, fixed minor typo
First evidence for electroweak radiative corrections from the new precision data
The analysis of the newest data on the leptonic Z-decays and m.sub(W) appears to reveal the first manifestations of electroweak radiative corrections. In fact, these data differ, at the level of 2.sigma., from their electroweak Born values, while they agree, to within 1.sigma., with the theoretical values which take the electroweak radiative corrections into account. Previous data were within 1.sigma. in agreement with both sets of values.The analysis of the newest data on the leptonic -decays and appears to reveal the first manifestations of electroweak radiative corrections. In fact, these data differ, at the level of , from their electroweak Born values, while they agree, to within , with the theoretical values which take the electroweak radiative corrections into account. Previous data were within in agreement with both sets of values
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 \Delta m =~ 1 GeV.Comment: 14 pages, 5 figure
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.Comment: 12 pages, latex, 14 figures, LaTEX, PS file and figures in EPS format
available at http://marwww.in2p3.fr/leptop/mugamma/mugamma.htm
Trialogue on the number of fundamental constants
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.Comment: Version appearing in JHEP; 31 pages late
Massive Electrodynamics and the Magnetic Monopoles
We investigate in detail the problem of constructing magnetic monopole
solutions within the finite-range electrodynamics (i.e., electrodynamics with
non-zero photon mass, which is the simplest extension of the standard theory;
it is fully compatible with the experiment). We first analyze the classical
electrodynamics with the additional terms describing the photon mass and the
magnetic charge; then we look for a solution analogous to the Dirac monopole
solution. Next, we plug the found solution into the Schr\"{o}dinger equation
describing the interaction between the the magnetic charge and the electron.
After that, we try to derive the Dirac quantization condition for our case.
Since gauge invariance is lost in massive electrodynamics, we use the method of
angular momentum algebra. Under rather general assumptions we prove the theorem
that the construction of such an algebra is not possible and therefore the
quantization condition cannot be derived. This points to the conclusion that
the Dirac monopole and the finite photon mass cannot coexist within one and the
same theory. Some physical consequences of this conclusion are considered. The
case of t'Hooft-Polyakov monopole is touched upon briefly.Comment: 24 pages, revtex, 1 figure appended as a PostScript fil
Extra generations and discrepancies of electroweak precision data
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 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 is between one and two extra
generations.Comment: 10 pages, TeX. An additional reference and P.P.S. about heavy higgs
are adde
Neutrino Wave Packets in Quantum Field Theory
We present a model of neutrino oscillations in the framework of quantum field
theory in which the propagating neutrino and the particles participating to the
production and detection processes are described by wave packets. The neutrino
state is a superposition of massive neutrino wave packets determined by the
production process, as naturally expected from causality. We show that the
energies and momenta of the massive neutrino components relevant for neutrino
oscillations are in general different from the average energies and momenta of
the propagating massive neutrino wave packets, because of the effects of the
detection process. Our results confirm the correctness of the standard
expression for the oscillation length of extremely relativistic neutrinos and
the existence of a coherence length.Comment: 25 page
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