144 research outputs found
Towards a matrix multi-level model of quark-gluon media
The key feature of the model is an infinite sequence of canonical immersions of groups: U(2) into U(3), U(2) into U(4), and so on. Let us refer to these groups as to levels: U(2) – the 0th level (that is, ours common), U(3) – the 1st, U(4) – the 2nd and so on. Levels relate to (quarks’) generations whereas flavor and color are also defined purely mathematically. According to the model, quarks can be interpreted as ‘sank’ protons (during the beginning of the reaction process, proton (or rather the support U(2) of its wave function) is merely pushed into a deeper level. The model seems to be compatible with detection of point-like constituents within the proton in highly inelastic electron-proton scattering (and with elastic electron-quark scattering). To introduce gluons, we deal with proton-antiproton pairs (tensor product). At each level, a gluon can be interpreted as a colored photon. Not each and every feature of the model coincides with the corresponding standard assumption about quarks and gluons. In particular, the total number of colors is level-dependent. The model predicts three new quarks (of the 4th generation)
Causal Topology in Future and Past Distinguishing Spacetimes
The causal structure of a strongly causal spacetime is particularly well
endowed. Not only does it determine the conformal spacetime geometry when the
spacetime dimension n >2, as shown by Malament and Hawking-King-McCarthy
(MHKM), but also the manifold dimension. The MHKM result, however, applies more
generally to spacetimes satisfying the weaker causality condition of future and
past distinguishability (FPD), and it is an important question whether the
causal structure of such spacetimes can determine the manifold dimension. In
this work we show that the answer to this question is in the affirmative. We
investigate the properties of future or past distinguishing spacetimes and show
that their causal structures determine the manifold dimension. This gives a
non-trivial generalisation of the MHKM theorem and suggests that there is a
causal topology for FPD spacetimes which encodes manifold dimension and which
is strictly finer than the Alexandrov topology. We show that such a causal
topology does exist. We construct it using a convergence criterion based on
sequences of "chain-intervals" which are the causal analogs of null geodesic
segments. We show that when the region of strong causality violation satisfies
a local achronality condition, this topology is equivalent to the manifold
topology in an FPD spacetime.Comment: 20 pages, 4 figures. Minor revisions. In particular, (i) terminology
in one of the Lemmas corrected, (ii) numbering of Lemmas, Theorems, etc.
uniformised. To appear in Classical and Quantum Gravit
The Random Discrete Action for 2-Dimensional Spacetime
A one-parameter family of random variables, called the Discrete Action, is
defined for a 2-dimensional Lorentzian spacetime of finite volume. The single
parameter is a discreteness scale. The expectation value of this Discrete
Action is calculated for various regions of 2D Minkowski spacetime. When a
causally convex region of 2D Minkowski spacetime is divided into subregions
using null lines the mean of the Discrete Action is equal to the alternating
sum of the numbers of vertices, edges and faces of the null tiling, up to
corrections that tend to zero as the discreteness scale is taken to zero. This
result is used to predict that the mean of the Discrete Action of the flat
Lorentzian cylinder is zero up to corrections, which is verified. The
``topological'' character of the Discrete Action breaks down for causally
convex regions of the flat trousers spacetime that contain the singularity and
for non-causally convex rectangles.Comment: 20 pages, 10 figures, Typos correcte
Measurement of decay rate and parameters at KEDR
Using the inclusive photon spectrum based on a data sample collected at the
peak with the KEDR detector at the VEPP-4M collider, we
measured the rate of the radiative decay as well
as mass and width. Taking into account an asymmetric photon
lineshape we obtained keV, MeV/, MeV.Comment: 6 pages, 3 figure
Measurement of J/psi to eta_c gamma at KEDR
We present a study of the inclusive photon spectra from 5.9 million J/psi
decays collected with the KEDR detector at the VEPP-4M e+e- collider. We
measure the branching fraction of radiative decay J/psi to eta_c gamma, eta_c
width and mass. Our preliminary results are: M(eta_c) = 2979.4+-1.5+-1.9 MeV,
G(eta_c) = 27.8+-5.1+-3.3 MeV, B(J/psi to eta_c gamma) = (2.34+-0.15+-0.40)%.Comment: To be published in Proceedings of the PhiPsi09, Oct. 13-16, 2009,
Beijing, Chin
Precise measurement of and between 1.84 and 3.72 GeV at the KEDR detector
The present work continues a series of the KEDR measurements of the value
that started in 2010 at the VEPP-4M collider. By combining new data
with our previous results in this energy range we measured the values of
and at nine center-of-mass energies between 3.08 and 3.72
GeV. The total accuracy is about or better than at most of energy
points with a systematic uncertainty of about . Together with the
previous precise measurement at KEDR in the energy range 1.84-3.05 GeV, it
constitutes the most detailed high-precision measurement near the
charmonium production threshold.Comment: arXiv admin note: text overlap with arXiv:1610.02827 and substantial
text overlap with arXiv:1510.0266
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