6,495 research outputs found
Exotic Searches
The experimental information on the search for non mesons as
glueballs, hybrids and multiquark states is reviewed. Candidate states which
are particularly amenable to detailed study by accumulating large samples of
, , decays at a -charm factory are discussed.Comment: 25 pages, LaTex, 22 Figures (available from the authors on request),
BARI-TH/94-17
Iterated uniform finite-state transducers
A deterministic iterated uniform finite-state transducer (for short, iufst) operates the same length-preserving transduction on several left-to-right sweeps. The first sweep occurs on the input string, while any other sweep processes the output of the previous one. We focus on constant sweep bounded iufsts. We study their descriptional power vs. deterministic finite automata, and the state cost of implementing language operations. Then, we focus on non-constant sweep bounded iufsts, showing a nonregular language hierarchy depending on sweep complexity
Ground deformation modeling of flank dynamics prior to the 2002 eruption of Mt. Etna
On 22 September 2002, 1 month before the
beginning of the flank eruption on the NE Rift, an M-3.7
earthquake struck the northeastern part of Mt. Etna, on the
westernmost part of the Pernicana fault. In order to
investigate the ground deformation pattern associated with
this event, a multi-disciplinary approach is presented here.
Just after the earthquake, specific GPS surveys were carried
out on two small sub-networks, aimed at monitoring the
eastern part of the Pernicana fault, and some baselines
belonging to the northeastern EDM monitoring network of
Mt. Etna were measured. The leveling route on the
northeastern flank of the volcano was also surveyed.
Furthermore, an investigation using SAR interferometry
was performed and also the continuous tilt data recorded at
a high precision sensor close to the epicenter were analyzed
to constrain the coseismic deformation. The results of the
geodetic surveys show a ground deformation pattern that
affects the entire northeastern flank of the volcano, clearly
shaped by the Pernicana fault, but too strong and wide to be
related only to an M-3.7 earthquake. Leveling and DInSAR
data highlight a local strong subsidence, up to 7 cm, close
to the Pernicana fault. Significant displacements, up to
2 cm, were also detected on the upper part of the NE Rift
and in the summit craters area, while the displacements decrease at lower altitude, suggesting that the dislocation
did not continue further eastward. Three-dimensional GPS
data inversions have been attempted in order to model the
ground deformation source and its relationship with the
volcano plumbing system. The model has also been
constrained by vertical displacements measured by the
leveling survey and by the deformation map obtained by
SAR interferometry
Multidisciplinary study of the Tindari Fault (Sicily, Italy) separating ongoing contractional and extensional compartments along the active Africa–Eurasia convergent boundary
The Africa–Eurasia convergence in Sicily and southern Calabria is currently expressed by two different tectonic
and geodynamic domains: thewestern region, governed by a roughlyN–S compression generated by a continental
collision; the eastern one, controlled by a NW–SE extension related to the south-east-directed expansion of
the Calabro–Peloritan Arc. The different deformation pattern of these two domains is accommodated by a
right-lateral shear zone (Aeolian–Tindari–Letojanni fault system) which, from the Ionian Sea, north of Mt.
Etna, extends across the Peloritani chain to the Aeolian Islands.
In this work, we study the evidence of active tectonics characterizing this shear zone, through the analysis of
seismic and geodetic data acquired by the INGV networks in the last 15 years. The study is completed by
structural and morphological surveys carried out between Capo Tindari and the watershed of the chain.
The results allowed defining a clear structural picture depicting the tectonic interferences between the two
different geodynamic domains. The results indicate that, besides the regional ~N130°E horizontal extensional
stress field, another one, NE–SW-oriented, is active in the investigated area. Both tension axes are mutually
independent and have been active up to the present at different times. The coexistence of these different
active horizontal extensions is the result of complex interactions between several induced stresses: 1) the
regional extension (NW–SE) related to the slab rollback and back-arc extension; 2) the strong uplift of the
chain; 3) the accommodation between compressional and extensional tectonic regimes along the Aeolian–
Tindari–Letojanni faults, through a SSE–NNW right-lateral transtensional displacement. In these conditions,
the greater and recurring uplift activity is not able to induce a radial extensional dynamics, but, under the
“directing” action of the shear system, it can only act on the regional extension (NW–SE) and produce the
second system of extension (NE–SW)
Study of the reaction pbar p -> phi phi from 1.1 to 2.0 GeV/c
A study has been performed of the reaction pbar p -> 4K using in-flight
antiprotons from 1.1 to 2.0 GeV/c incident momentum interacting with a hydrogen
jet target. The reaction is dominated by the production of a pair of phi
mesons. The pbar p -> phi phi cross section rises sharply above threshold and
then falls continuously as a function of increasing antiproton momentum. The
overall magnitude of the cross section exceeds expectations from a simple
application of the OZI rule by two orders of magnitude. In a fine scan around
the xi/f_J(2230) resonance, no structure is observed. A limit is set for the
double branching ratio B(xi -> pbar p) * B(xi -> phi phi) < 6e-5 for a spin 2
resonance of M = 2.235 GeV and Width = 15 MeV.Comment: 13 pages, 13 figures, 2 tables, Latex. To be published in Phys. Rev.
A preliminary census of engineering activities located in Sicily (Southern Italy) which may “potentially” induce seismicity
The seismic events caused by human engineering activities are commonly termed as “triggered” and “induced”.
This class of earthquakes, though characterized by low-to-moderate magnitude, have significant social and eco-
nomical implications since they occur close to the engineering activity responsible for triggering/inducing them
and can be felt by the inhabitants living nearby, and may even produce damage. One of the first well-documented
examples of induced seismicity was observed in 1932 in Algeria, when a shallow magnitude 3.0 earthquake
occurred close to the Oued Fodda Dam. By the continuous global improvement of seismic monitoring networks,
numerous other examples of human-induced earthquakes have been identified. Induced earthquakes occur at
shallow depths and are related to a number of human activities, such as fluid injection under high pressure
(e.g. waste-water disposal in deep wells, hydrofracturing activities in enhanced geothermal systems and oil
recovery, shale-gas fracking, natural and CO2 gas storage), hydrocarbon exploitation, groundwater extraction,
deep underground mining, large water impoundments and underground nuclear tests. In Italy, induced/triggered
seismicity is suspected to have contributed to the disaster of the Vajont dam in 1963. Despite this suspected case
and the presence in the Italian territory of a large amount of engineering activities “capable” of inducing seismicity,
no extensive researches on this topic have been conducted to date. Hence, in order to improve knowledge and
correctly assess the potential hazard at a specific location in the future, here we started a preliminary study on the
entire range of engineering activities currently located in Sicily (Southern Italy) which may “potentially” induce
seismicity. To this end, we performed:
• a preliminary census of all engineering activities located in the study area by collecting all the useful information
coming from available on-line catalogues;
• a detailed compilation of instrumental and historical seismicity, focal mechanisms solutions, multidisciplinary
stress indicators, GPS-based ground deformation field, mapped faults, etc by merging data from on-line catalogues
with those reported in literature.
Finally, for each individual site, we analysed: i) long-term statistic behaviour of instrumental seismicity (mag-
nitude of completeness, seismic release above a threshold magnitude, depth distribution, focal plane solutions);
ii) long-term statistic behaviour of historical seismicity (maximum magnitude estimation, recurrence time inter-
val, etc); iii) properties and orientation of faults (length, estimated geological slip, kinematics, etc); iv) regional
stress (from borehole, seismological and geological observations) and strain (from GPS-based observations) fields.UnpublishedVienna (Austria)6T. Sismicità indotta e caratterizzazione sismica dei sistemi naturaliope
Measuring the Relative Strong Phase in and Decays
In a recently suggested method for measuring the weak phase in
decays, the relative strong phase in and decays (equivalently, in and \od \to K^{*+} K^-) plays a role. It is shown how a study of
the Dalitz plot in can yield information on this phase,
and the size of the data sample which would give a useful measurement is
estimated.Comment: 13 pages, latex, 5 figures, submitted to Phys. Rev. D. Appendix and
some text on additional resonant contributions adde
Scalar Mesons in a Chiral Quark Model with Glueball
Ground-state scalar isoscalar mesons and a scalar glueball are described in a
U(3)xU(3) chiral quark model of the Nambu--Jona-Lasinio (NJL) type with 't
Hooft interaction. The latter interaction produces singlet-octet mixing in the
scalar and pseudoscalar sectors. The glueball is introduced into the effective
meson Lagrangian as a dilaton on the base of scale invariance. The mixing of
the glueball with scalar isoscalar quarkonia and amplitudes of their decays
into two pseudoscalar mesons are shown to be proportional to current quark
masses, vanishing in the chiral limit. Mass spectra of the scalar mesons and
the glueball and their main modes of strong decay are described.Comment: 10 pages, LaTeX text, requires svjour.cls and svepj.cl
f0(980) meson as a K bar K molecule in a phenomenological Lagrangian approach
We discuss a possible interpretation of the f0(980) meson as a hadronic
molecule - a bound state of K and bar K mesons. Using a phenomenological
Lagrangian approach we calculate the strong f0(980) to pi pi and
electromagnetic f0(980) to gamma gamma decays. The compositeness condition
provides a self-consistent method to determine the coupling constant between f0
and its constituents, K and bar K. Form factors governing the decays of the
f0(980) are calculated by evaluating the kaon loop integrals. The predicted
f0(980) to pi pi and f0(980) to gamma gamma decay widths are in good agreement
with available data and results of other theoretical approaches.Comment: 21 pages, 11 figures, revised version accepted for publication in
Eur. Phys. J.
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