1,362 research outputs found
-Matrix of Nonlocal Scalar Quantum Field Theory in the Representation of Basis Functions
Nonlocal quantum theory of one-component scalar field in -dimensional
Euclidean spacetime is studied in representations of -matrix
theory for both polynomial and nonpolynomial interaction Lagrangians. The
theory is formulated on coupling constant in the form of an infrared smooth
function of argument for space without boundary. Nonlocality is given by
evolution of Gaussian propagator for the local free theory with ultraviolet
form factors depending on ultraviolet length parameter . By representation
of the -matrix in terms of abstract functional integral over
primary scalar field, the form of a grand canonical partition
function is found. And, by expression of -matrix in terms of the
partition function, the representation for in terms of basis
functions is obtained. Derivations are given for discrete case where basis
functions are Hermite functions, and for continuous case where basis functions
are trigonometric functions. The obtained expressions for the
-matrix are investigated within the framework of variational
principle based on Jensen inequality. Equations with separable kernels
satisfied by variational function are found and solved, yielding results
for both the polynomial theory and the nonpolynomial sine-Gordon
theory. A new definition of the -matrix is proposed to solve
additional divergences which arise in application of Jensen inequality for the
continuous case. Analytical results are illustrated numerically. For simplicity
of numerical calculation: the case is considered, and propagator for the
free theory is in the form of Gaussian function typically in the
Virton-Quark model. The formulation for nonlocal QFT in momentum space of
extra dimensions with subsequent compactification into physical spacetime is
discussed.Comment: 38 pages, 18 figures; v2: significant text editing; v3: text and
plots edited, references and acknowledgments added; prepared for the special
issue of the journal Particles in memory of G.V. Efimo
Nonlocal Scalar Quantum Field Theory: Functional Integration, Basis Functions Representation and Strong Coupling Expansion
Nonlocal QFT of one-component scalar field in -dimensional
Euclidean spacetime is considered. The generating functional (GF) of complete
Green functions as a functional of external source , coupling
constant , and spatial measure is studied. An expression for GF
in terms of the abstract integral over the primary field
is given. An expression for GF in terms of integrals
over the primary field and separable Hilbert space (HS) is obtained by means of
a separable expansion of the free theory inverse propagator over the
separable HS basis. The classification of functional integration measures
is formulated, according to which trivial and
two nontrivial versions of GF are obtained. Nontrivial versions
of GF are expressed in terms of -norm and -norm,
respectively. The definition of the -norm generator is suggested.
Simple cases of sharp and smooth generators are considered. Expressions for GF
in terms of integrals over the separable HS with new integrands
are obtained. For polynomial theories and for
the nonpolynomial theory , integrals over the separable HS in
terms of a power series over the inverse coupling constant for
both norms (-norm and -norm) are calculated. Critical values of model
parameters when a phase transition occurs are found numerically. A
generalization of the theory to the case of the uncountable integral over HS is
formulated. A comparison of two GFs , one in the case of
uncountable HS integral and one obtained using the Parseval-Plancherel
identity, is given.Comment: 26 pages, 2 figures; v2: significant additions in the text; prepared
for the special issue "QCD and Hadron Structure" of the journal Particles;
v3: minimal corrections; v4: paragraphs added related to Reviewer comment
Revisiting the 'LSND anomaly' II: critique of the data analysis
This paper, together with a preceding paper, questions the so-called 'LSND
anomaly': a 3.8 sigma excess of antielectronneutrino interactions over standard
backgrounds, observed by the LSND Collaboration in a beam dump experiment with
800 MeV protons. That excess has been interpreted as evidence for the
antimuonneutrino to antielectronneutrino oscillation in the \Deltam2 range from
0.2 eV2 to 2 eV2. Such a \Deltam2 range is incompatible with the widely
accepted model of oscillations between three light neutrino species and would
require the existence of at least one light 'sterile' neutrino. In a preceding
paper, it was concluded that the estimates of standard backgrounds must be
significantly increased. In this paper, the LSND Collaboration's estimate of
the number of antielectronneutrino interactions followed by neutron capture,
and of its error, is questioned. The overall conclusion is that the
significance of the 'LSND anomaly' is not larger than 2.3 sigma.Comment: 30 pages, 16 figures, 6 table
Why the paper CERN-PH-EP-2009-015 (arXiv:0903.4762) is scientifically unacceptable
The paper CERN-PH-EP-2009-015 (arXiv:0903.4762) by A. Bagulya et al. violates
standards of quality of work and scientific ethics on several counts. The paper
contains assertions that contradict established detector physics. The paper
falls short of proving the correctness of the authors' concepts and results.
The paper ignores or quotes misleadingly pertinent published work. The paper
ignores the fact that the authors' concepts and results have already been shown
wrong in the published literature. The authors seem unaware that cross-section
results from the 'HARP Collaboration' that are based on the paper's concepts
and algorithms are in gross disagreement with the results of a second analysis
of the same data, and with the results of other experiments.Comment: 8 pages, 3 figure
Reply to 'Corrections to the HARP-CDP Analysis of the LSND Neutrino Oscillation Backgrounds'
The alleged mistakes in recent papers that reanalyze the backgrounds to the
'LSND anomaly' do not exist. We maintain our conclusion that the significance
of the 'LSND anomaly' is not 3.8 sigma but not larger than 2.3 sigma.Comment: 3 page
Cross-sections of large-angle hadron production in proton- and pion-nucleus interactions VII: tin nuclei and beam momenta from \pm3 GeV/c to \pm15 GeV/c
We report on double-differential inclusive cross-sections of the production
of secondary protons, charged pions, and deuterons, in the interactions with a
5% nuclear interaction length thick stationary tin target, of proton and pion
beams with momentum from \pm3 GeV/c to \pm15 GeV/c. Results are given for
secondary particles with production angles between 20 and 125 degrees.
Cross-sections on tin nuclei are compared with cross-sections on beryllium,
carbon, copper, tantalum and lead nuclei.Comment: 68 pages, 13 figure
Comparison of Geant4 hadron generation with data from the interactions with beryllium nuclei of +8.9 GeV/c protons and pions, and of -8 GeV/c pions
Hadron generation in the Geant4 simulation tool kit is compared with
inclusive spectra of secondary protons and pions from the interactions with
beryllium nuclei of +8.9 GeV/c protons and pions, and of -8.0 GeV/c pions. The
data were taken in 2002 at the CERN Proton Synchrotron with the HARP
spectrometer. We report on significant disagreements between data and simulated
data especially in the polar-angle distributions of secondary protons and
pions.Comment: 15 pages, 13 figure
- …