1,704 research outputs found
A general class of phase transition models with weighted interface energy
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Form Factors and Correlation Functions of the Stress--Energy Tensor in Massive Deformation of the Minimal Models
The magnetic deformation of the Ising Model, the thermal deformations of both
the Tricritical Ising Model and the Tricritical Potts Model are governed by an
algebraic structure based on the Dynkin diagram associated to the exceptional
algebras (respectively for ). We make use of these underlying
structures as well as of the discrete symmetries of the models to compute the
matrix elements of the stress--energy tensor and its two--point correlation
function by means of the spectral representation method.Comment: 52 page
Mathematical structure of the temporal gauge
The mathematical structure of the temporal gauge of QED is critically
examined in both the alternative formulations characterized by either
positivity or regularity of the Weyl algebra. The conflict between time
translation invariance and Gauss law constraint is shown to lead to peculiar
features. In the positive case only the correlations of exponentials of fields
exist (non regularity), the space translations are not strongly continuous, so
that their generators do not exist, a theta vacuum degeneracy occurs,
associated to a spontaneous symmetry breaking. In the indefinite case the
spectral condition only holds in terms of positivity of the energy, gauge
invariant theta-vacua exist on the observables, with no extension to time
translation invariant states on the field algebra, the vacuum is faithful on
the longitudinal algebra and a KMS structure emerges. Functional integral
representations are derived in both cases, with the alternative between ergodic
measures on real random fields or complex Gaussian random fields.Comment: Late
SiPM and front-end electronics development for Cherenkov light detection
The Italian Institute of Nuclear Physics (INFN) is involved in the
development of a demonstrator for a SiPM-based camera for the Cherenkov
Telescope Array (CTA) experiment, with a pixel size of 66 mm. The
camera houses about two thousands electronics channels and is both light and
compact. In this framework, a R&D program for the development of SiPMs suitable
for Cherenkov light detection (so called NUV SiPMs) is ongoing. Different
photosensors have been produced at Fondazione Bruno Kessler (FBK), with
different micro-cell dimensions and fill factors, in different geometrical
arrangements. At the same time, INFN is developing front-end electronics based
on the waveform sampling technique optimized for the new NUV SiPM. Measurements
on 11 mm, 33 mm, and 66 mm NUV SiPMs
coupled to the front-end electronics are presentedComment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
On the Form Factors of Relevant Operators and their Cluster Property
We compute the Form Factors of the relevant scaling operators in a class of
integrable models without internal symmetries by exploiting their cluster
properties. Their identification is established by computing the corresponding
anomalous dimensions by means of Delfino--Simonetti--Cardy sum--rule and
further confirmed by comparing some universal ratios of the nearby
non--integrable quantum field theories with their independent numerical
determination.Comment: Latex file, 35 pages with 5 Postscript figure
Boundary Asymptotic Analysis for an Incompressible Viscous Flow: Navier Wall Laws
We consider a new way of establishing Navier wall laws. Considering a bounded
domain of R N , N=2,3, surrounded by a thin layer ,
along a part 2 of its boundary , we consider a
Navier-Stokes flow in with
Reynolds' number of order 1/ in . Using
-convergence arguments, we describe the asymptotic behaviour of the
solution of this problem and get a general Navier law involving a matrix of
Borel measures having the same support contained in the interface 2. We
then consider two special cases where we characterize this matrix of measures.
As a further application, we consider an optimal control problem within this
context
Correlation Functions in the Two-dimensional Ising Model in a Magnetic Field at
The one and two-particle form factors of the energy operator in the
two-dimensional Ising model in a magnetic field at are exactly computed
within the form factor bootstrap approach. Together with the matrix elements of
the magnetisation operator already computed in ref.\,\cite{immf}, they are used
to write down the large distance expansion for the correlators of the two
relevant fields of the model.Comment: 18 pages, latex, 7 table
Form factors in the Bullough-Dodd related models: The Ising model in a magnetic field
We consider particular modification of the free-field representation of the
form factors in the Bullough-Dodd model. The two-particles minimal form factors
are excluded from the construction. As a consequence, we obtain convenient
representation for the multi-particle form factors, establish recurrence
relations between them and study their properties. The proposed construction is
used to obtain the free-field representation of the lightest particles form
factors in the perturbed minimal models. As a significant example
we consider the Ising model in a magnetic field. We check that the results
obtained in the framework of the proposed free-field representation are in
agreement with the corresponding results obtained by solving the bootstrap
equations.Comment: 20 pages; v2: some misprints, textual inaccuracies and references
corrected; some references and remarks adde
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