Quest for precision in hadronic cross sections at low energy: Monte Carlo tools vs.
experimental data by Actis, S. (Paul-Scherrer-Institute Wuerenlingen and Villigen, Villigen (Switzerland));
Arbuzov, A. (Joint Institute for Nuclear Research, Dubna (Russian Federation). Bogoliubov
Lab. of Theoretical Physics); Balossini, G. (Pavia Univ. (Italy). Dipt. di Fisica
Nucleare e Teorica; INFN, Pavia (Italy)) (and others); Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Working group on radiative
corrections and Monte Carlo generators for low energies Read MoreCollapse
[en]
We present the achievements of the last years of the experimental and theoretical
groups working on hadronic cross section measurements at the low energy e^{+}e^{-}
colliders in Beijing, Frascati, Ithaca, Novosibirsk, Stanford and Tsukuba and on τ
decays. We sketch the prospects in these fields for the years to come. We emphasise
the status and the precision of the Monte Carlo generators used to analyse the hadronic
cross section measurements obtained as well with energy scans as with radiative return,
to determine luminosities and τ decays. The radiative corrections fully or approximately
implemented in the various codes and the contribution of the vacuum polarisation are
discussed. (orig.)$$$$
Cosmological horizons and reconstruction of quantum field theories 643 KB - http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/39/011/39011696.pdf - Text Version by Dappiaggi, C.; Pinamonti, N. (Hamburg Univ. (Germany). 2. Inst. fuer Theoretische
Physik; Trento Univ., Povo (Italy). Istituto Nazionale di Alta Matematica ''F. Severi''
- GNFM); Moretti, V. (Trento Univ. (Italy). Dipt. di Matematica; Istituto Nazionale
di Fisica Nucleare - Gruppo Collegato di Trento, Povo (Italy)); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany) Read MoreCollapse
[en]
As a starting point for this manuscript, we remark how the cosmological horizon of
a certain class of Friedmann-Robertson-Walker backgrounds shares some non trivial
geometric properties with null infinity in an asymptotically flat spacetime. Such
a feature is generalized to a larger class of expanding spacetimes M admitting a geodesically
complete cosmological horizon J^{-} common to all co-moving observers. This
property is later exploited in order to recast, in a cosmological background, some
recent results for a linear scalar quantum field theory in spacetimes asymptotically
flat at null infinity. Under suitable hypotheses on M - valid for de Sitter spacetime
and some other FRW spacetimes obtained by perturbing deSitter space - the algebra
of observables for a Klein-Gordon field is mapped into a subalgebra of the algebra
of observables W(J^{-}) constructed on the cosmological horizon. There is
exactly one pure quasifree state λ on W(J^{-}) which fulfills a suitable energy
positivity condition with respect to a generator related with the cosmological time
displacements. Furthermore λ induces a preferred physically meaningful quantum state
λ_{M} for the quantum theory in the bulk. If M admits a timelike Killing generator
preserving J^{-}, then the associated self-adjoint generator in the GNS representation
of λ_{M} has positive spectrum (i.e. energy). Moreover λ_{M} turns
out to be invariant under every symmetry of the bulk metric which preserves the cosmological
horizon. In the case of an expanding de Sitter spacetime, λ_{M} coincides
with the Euclidean (Bunch-Davies) vacuum state, hence being Hadamard in this case.
Remarks on the validity of the Hadamard property for λ_{M} in more general
spacetimes are presented. (orig.)$$$$
A simple recursive expansion algorithm for the integrals of tree level superstring
five point amplitudes in a flat background is given which reduces the expansion to
simple symbol(ic) manipulations. This approach can be used for instance to prove the
expansion is maximally transcendental to all orders and to verify several conjectures
made in recent literature to high order. Closed string amplitudes follow from these
open string results by the KLT relations. To obtain insight into these results in
particular the maximal R-symmetry violating amplitudes (MRV) in type IIB superstring
theory are studied. The obtained expansion of the open string amplitudes reduces the
analysis for MRV amplitudes to the classification of completely symmetric polynomials
of the external legs, up to momentum conservation. Using Molien's theorem as a counting
tool this problem is solved by constructing an explicit nine element basis for this
class. This theorem may be of wider interest: as is illustrated at higher points it
can be used to calculate dimensions of polynomials of external momenta invariant under
any finite group for in principle any number of legs, up to momentum conservation$$$$
I present the result of the data collected by the MEG detector at the Paul Scherrer
Institut in 2009 and 2010 in search for the lepton flavour violating decay μ→eγ with
a sensitivity of 1.6×10^{−12}$$$$
Cosmic string interactions in a Lorentz invariance violation framework 44 KB - http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/41/131/41131115.pdf - Text Version by Ferreira, Cristine Nunes (Instituto Federal de Educacao, Ciencia e Tecnologia Fluminense,
Campos dos Goytacases, RJ (Brazil)); Helayel Neto, Jose Abdalla; Lima, Carlos Eduardo
Campos (Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)); Sociedade Brasileira de Fisica (SBF), Sao Paulo, SP (Brazil) Read MoreCollapse
Angular correlations in three-jet events in ep collisions at HERA 931 KB - http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/39/112/39112429.pdf - Text Version by Chekanov, S.; Derrick, M.; Magill, B. (Argonne National Laboratory, Illinois (United
States)) (and others); Deutsches Elektronen-Synchrotron (DESY). Hamburg (Germany); ZEUS Collaboration Read MoreCollapse
[en]
Three-jet production in deep inelastic ep scattering and photoproduction was investigated
with the ZEUS detector at HERA using an integrated luminosity of 127 pb^{-1}.
Measurements of differential cross sections are presented as functions of angular
correlations between the three jets in the final state and the proton-beam direction.
These correlations provide a stringent test of perturbative QCD and show sensitivity
to the contributions from different colour configurations. Fixed-order perturbative
QCD calculations assuming the values of the colour factors C_{F}, C_{A}
and T_{F} as derived from a variety of gauge groups were compared to the measurements
to study the underlying gauge group symmetry. The measured angular correlations in
the deep inelastic ep scattering and photoproduction regimes are consistent with the
admixture of colour configurations as predicted by SU(3) and disfavour other symmetry
groups, such as SU(N) in the limit of large N$$$$
Right-handed sector lepto-genesis by Frigerio, M. (CEA Saclay, Service de Physique Theorique, 91 - Gif-sur-Yvette (France));
Hambye, Th. (Madrid Universidad Autonoma, Instituto de F sica Te rica, Cantoblanco
(Spain)); Ma, E. (California Univ., Physics Dept., Riverside, California (United States)); CEA Saclay, Service de Physique Theorique, 91 - Gif-sur-Yvette (France) Read MoreCollapse
[en]
Instead of creating the observed baryon asymmetry of the universe by the decay of
right-handed (RH) neutrinos to left-handed leptons, we propose to generate it dominantly
by the decay of the RH neutrinos to RH leptons. This mechanism turns out to be successful
in large regions of the parameter space. It may work, in particular, at a scale as
low as a few TeV, with no need to invoke quasi-degenerate RH neutrino masses to resonantly
enhance the asymmetry. Such a possibility can be probed experimentally by the observation
at colliders of a singlet charged Higgs particle and of RH neutrinos. Other mechanisms
which may lead to successful lepton-genesis from the RH lepton sector interactions
are also briefly presented. The incorporation of these scenarios in left-right symmetric
and unified models is discussed. (authors)$$$$
Cellular Automata for Modeling the field-scale erosion by Diaz Suarez, Jorge; Bagarotti Marin, Angel; Ruiz Perez, Maria Elena (Universidad Agraria
de la Habana, autopista nacional Km 23 1/2, San Jose de las Lajas, Provincia Habana
(Cuba)) fromProceedings of 11. Symposium and 9. Congress of the Cuban Society of Physics. International
Symposium: Physics on the 150th Anniversary of Max Planck's Birth Read MoreCollapse
[en]
Full text: The Cellular Automaton (CA) is a system used discrete dynamic modeling
of many physical systems. Their fundamental properties are the interaction at the
local level, homogeneity and parallelism. It has been used as a secondary for the
simulation of large systems where the use of equations in partial derivatives is complex
and costly from the computational point of view. On the other hand, the high complexity
of spatial interaction in the processes involved in the erosion-transport-deposition
of sediments at field level, considerably limiting the use of base models physics.
The objective of this study is to model the main processes involved in erosion water
supply of soils through the use of the CAMELot system, based on an extension of the
original paradigm of the CA. The CAMELot system has been used in the simulation of
systems of large spatial extent, where the laws of local interaction between automata
have a deep physical sense. This system guarantees both the input of the necessary
specifications and simulation in parallel, as the visualization and the general management
of the system. They are exposed to each of the submodels used in it and the overall
dynamics of the system is analyzed. (author)$$$$
Orig. TitleModelacion por Cellular Automata de la erosion a escala de campo SubjectENVIRONMENTAL SCIENCES (S54), PHYSICS OF ELEMENTARY PARTICLES AND FIELDS (S72) Source/ReportUniversidad de La Habana (UH), La Habana (Cuba); 104 p; 11 Jun 2008; p. 19; 11. Symposium and 9. Congress of the Cuban Society of Physics; International Symposium: Physics on the 150. Anniversary of Max Planck's Birth; Havana (Cuba); Havana (Cuba); 7-11 Jul 2008; 7-11 Jul 2008; INIS-CU--0022; Available in abstract form only, full text entered in this record; Available in abstract form only, full text entered in each record Record TypeMiscellaneous Country/Org.Cuba DEICOST, DEPOSITION, EQUATIONS, EROSION, INTERACTIONS, MANAGEMENT, SEDIMENTS, SIMULATION, SOILS, WATER SUPPLY LanguageSpanish Ref. Number45066074 Rel. Record45063742 Publ. Year2008 INIS Volume45 INIS Issue25
The two-loop soft current in dimensional regularization http://dx.doi.org/10.1016/j.physletb.2013.10.063 by Duhr, Claude (Institute for Theoretical Physics, ETH Zürich, 8093 Zürich (Switzerland);
Institute for Particle Physics Phenomenology, University of Durham, Durham, DH1 3LE
(United Kingdom)); Gehrmann, Thomas (Institut für Theoretische Physik, Universität
Zürich, Winterthurerstrasse 190, 8057 Zürich (Switzerland); Kavli Institute for Theoretical
Physics, University of California, Santa Barbara, CA 93106 (United States)), E-mail:
duhrc@itp.phys.ethz.ch, E-mail: thomas.gehrmann@uzh.ch Read MoreCollapse
[en]
The soft current describes the factorization behavior of quantum chromodynamics (QCD)
scattering amplitudes in the limit of vanishing energy of one of the external partons.
It is process-independent and can be expanded in a perturbative series in the coupling
constant. To all orders in the dimensional regularization parameter, we compute the
two-loop correction to the soft current for processes involving two hard partons$$$$
Measurements are presented of diffractive D* meson production in deep-inelastic scattering
(DIS) and photoproduction (γp) at HERA. The event topology is given by ep→eXY where
a central system X contains at least one D^{*±} meson and is well separated
by a large rapidity gap from a leading low-mass proton remnant system Y. The analyzed
data were collected with the H1 detector in the years 1999 and 2000 and correspond
to an integrated luminosity of 47.0 pb^{-1}. The measurements are compared
to QCD predictions in NLO, based on diffractive parton density functions previously
obtained from a QCD analysis of the diffractive structure function F_{2}^{D(3)}
at H1. A good agreement is observed in the full kinematic regime, which supports the
validity of QCD factorization in DIS and γp. (orig.)$$$$