280 research outputs found
The flight of Arcadia: spatial CO2/SO2 variations in a cross section above the Nord East crater of Etna volcano
The CO2/SO2 ratio in volcanic plumes of open conduit volcanoes can provide useful information about the magma depth inside a conduit and the possible occurrence of an eruptive event. Moreover, the same CO2 measurement when combined with a SO2 flux measurement, commonly carried out at many volcanoes nowadays, is used to contribute to an improved estimate of global volcanic CO2 budget. Today worldwide at 13 volcanoes automated in-situ instruments (known as Multi-GAS stations) are applied to continuously determine CO2/SO2 ratios and to use this signal as additional parameter for volcanic monitoring. Usually these instruments carry out measurements of half an hour 4 – 6 times/day and thus provide continuous CO2/SO2 values and their variability. The stations are located at crater rims in a position that according to the prevailing winds is invested by the plume. Obviously, although the stations are carefully positioned, it is inevitable that other sources than the plume itself, e.g. soil degassing and surrounding fumaroles, contribute and will be measured as well, covering the ‘real’ values. Between July and September 2014 experiments were carried out on the North East crater (NEC) of Mount Etna, installing a self-made cable car that crossed the crater from one side to the other. The basket, called “Arcadia”, was equipped with an automated standard Multi-GAS station and a GPS, which acquired at high frequency (0.5 Hz) the following parameters : CO2, SO2, H2S, Rh, T, P and geo-coordinates. The choice of NEC of the volcano Etna was based on its accessibility, the relative small diameter (about 230 m) and the presence of a relatively constant and rather concentrated plume. Actually, NEC belongs also to the monitoring network EtnaPlume (managed by the INGV of Palermo). The aim of these experiments was to observe variations of each parameter, in particular the fluctuation of the CO2/SO2 ratio within the plume, moving from the edge to the center of the crater. The gained results give a first possibility to understand if common measurements carried out at the edge of a crater are subject to overor underestimation and about the order of derivations caused by other sources than the plume. A preliminary analysis results in a lower CO2/SO2 ratio in the central part of the crater versus the more peripheral one. The deviation between the average CO2/SO2 ratio and the center of the plume ranges from a minimum of 58% up to a maximum of 74%. An increased CO2/SO2 emission could be caused by the influence of soil and/or fumarolic degassing at the crater rim. This interpretation leads us to the conclusion that measurements by fixed installed stations might overestimate the CO2/SO2 ratio compared to values originating from the “pure” plume. Further on, it means that variations of up to 74%(in our experiment) don’t necessarily correlate with volcanic activity changes
Reply to comment from Liotta and Rizzo on “Evolution of CO2 , SO2 , HCl and HNO3 in the volcanic plumes from Etna” by Voigt et al. [Geophys. Res. Lett.; 41, doi:10.1002/2013GL058974]
Editor’s Note:
The following comment and reply arise from an article
published in Geophysical Research Letters by Voigt
et al. (2014). The article addresses a volcanology topic,
and the commenters take issue with some conclusions
and offer an analysis of their own. Voigt and co-authors
have responded.
Why is this comment-and-reply being published in
the Bulletin? It is because Geophysical Research
Letters is one of a number of journals that do not offer
any published forum for discussion of the papers they
publish. This is a matter of editorial policy and a
decision for each journal.
The Bulletin of Volcanology does provide a forum for
discussion of articles published. When contacted by
Marcello Liotta with the request that the Bulletin consider
hosting a discussion of the Voigt et al. volcanology article in
GRL, I agreed to do so if the GRL authors were willing to
engage with the comment. Voigt and co-authors were willing
to do so and have been allowed a small amount of additional
space to summarize for Bulletin readers the key points of the
GRL paper under discussion before responding directly to the
comment from Liotta and Rizzo.
I hope that Bulletin readers find the discussion and reply of
interest
The Impact of a 4th Generation on Mixing and CP Violation in the Charm System
We study D0-D0 mixing in the presence of a fourth generation of quarks. In
particular, we calculate the size of the allowed CP violation which is found at
the observable level well beyond anything possible with CKM dynamics. We
calculate the semileptonic asymmetry a_SL and the mixing induced CP asymmetry
eta_fS_f which are correlated with each other. We also investigate the
correlation of eta_fS_f with a number of prominent observables in other mesonic
systems like epsilon'/epsilon, Br(K_L -> pi0 nu nu), Br(K+ -> pi+ nu nu),
Br(B_s ->mu+ mu-), Br(B_d -> mu+ mu-) and finally S_psi phi in the B_s system.
We identify a clear pattern of flavour and CP violation predicted by the SM4
model: While simultaneous large 4G effects in the K and D systems are possible,
accompanying large NP effects in the B_d system are disfavoured. However this
behaviour is not as pronounced as found for the LHT and RSc models. In contrast
to this, sizeable CP violating effects in the B_s system are possible unless
extreme effects in eta_fS_f are found, and Br(B_s ->mu+ mu-) can be strongly
enhanced regardless of the situation in the D system. We find that, on the
other hand, S_psi phi > 0.2 combined with the measured epsilon'/epsilon
significantly diminishes 4G effects within the D system.Comment: 22 pages, 23 figures, v2 (references added
Abel Symposia
Discrete Morse theory has recently lead to new developments in the theory of random geometric complexes. This article surveys the methods and results obtained with this new approach, and discusses some of its shortcomings. It uses simulations to illustrate the results and to form conjectures, getting numerical estimates for combinatorial, topological, and geometric properties of weighted and unweighted Delaunay mosaics, their dual Voronoi tessellations, and the Alpha and Wrap complexes contained in the mosaics
Characterising New Physics Models by Effective Dimensionality of Parameter Space
We show that the dimension of the geometric shape formed by the
phenomenologically valid points inside a multi-dimensional parameter space can
be used to characterise different new physics models and to define a
quantitative measure for the distribution of the points. We explain a simple
algorithm to determine the box-counting dimension from a given set of parameter
points, and illustrate our method with examples from different models that have
recently been studied with respect to precision flavour observables.Comment: 14 pages, 8 figure
A Search for leptophilic Z_(l) boson at future linear colliders
We study the possible dynamics associated with leptonic charge in future
linear colliders. Leptophilic massive vector boson, Z_(l), have been
investigated through the process e^(+)e^(-) -> mu^(+)mu^(-). We have shown that
ILC and CLIC will give opportunity to observe Z_(l) with masses up to the
center of mass energy if the corresponding coupling constant g_(l) exceeds
10^(-3).Comment: 12 pages, 10 figure
Simultaneous Extraction of the Fermi constant and PMNS matrix elements in the presence of a fourth generation
Several recent studies performed on constraints of a fourth generation of
quarks and leptons suffer from the ad-hoc assumption that 3 x 3 unitarity holds
for the first three generations in the neutrino sector. Only under this
assumption one is able to determine the Fermi constant G_F from the muon
lifetime measurement with the claimed precision of G_F = 1.16637 (1) x 10^-5
GeV^-2. We study how well G_F can be extracted within the framework of four
generations from leptonic and radiative mu and tau decays, as well as from K_l3
decays and leptonic decays of charged pions, and we discuss the role of lepton
universality tests in this context. We emphasize that constraints on a fourth
generation from quark and lepton flavour observables and from electroweak
precision observables can only be obtained in a consistent way if these three
sectors are considered simultaneously. In the combined fit to leptonic and
radiative mu and tau decays, K_l3 decays and leptonic decays of charged pions
we find a p-value of 2.6% for the fourth generation matrix element |U_{e 4}|=0
of the neutrino mixing matrix.Comment: 19 pages, 3 figures with 16 subfigures, references and text added
refering to earlier related work, figures and text in discussion section
added, results and conclusions unchange
On CP Asymmetries in Two-, Three- and Four-Body D Decays
Indirect and direct CP violations have been established in K_L and B_d
decays. They have been found in two-body decay channels -- with the exception
of K_L to pi^+ pi^- e^+ e^- transitions. Evidence for direct CP asymmetry has
just appeared in LHCb data on A_{CP}(D^0 to K^+ K^-) - A_{CP}(D^0 to pi^+ pi^-)
with 3.5 sigma significance. Manifestations of New Dynamics (ND) can appear in
CP asymmetries just below experimental bounds. We discuss D^{\pm}_{(s)},
D^0/\bar D^0 and D_L/D_S transitions to 2-, 3- and 4-body final states with a
comment on predictions for inclusive vs. exclusive CP asymmetries. In
particular we discuss T asymmetries in D to h_1 h_2 l^+ l^- in analogy with K_L
to pi^+ pi^- e^+ e^- transitions due to interference between M1, internal
bremsstrahlung and possible E1 amplitudes. Such an effect depends on the
strength of CP violation originating from the ND -- as discussed here for
Little Higgs Models with T parity and non-minimal Higgs sectors -- but also in
the interferences between these amplitudes even in the Standard Model (SM).
More general lessons can be learnt for T asymmetries in non-leptonic D decays
like D to h_1h_2 h_3 h_4. Such manifestations of ND can be tested at LHCb and
other Super-Flavour Factories like the projects at KEK near Tokyo and at Tor
Vergata/Frascati near Rome.Comment: 27 pages, 6 figures. Revised with current results from LHCb and HFAG
and further interpretation
New Physics in Bs -> J/psi phi: a General Analysis
Recently, the CDF and D0 collaborations measured indirect CP violation in Bs
-> J/psi phi and found a hint of a signal. If taken at face value, this can be
interpreted as a nonzero phase of Bs-Bsbar mixing (beta_s), in disagreement
with the standard model, which predicts that beta_s ~= 0. In this paper, we
argue that this analysis may be incomplete. In particular, there can be new
physics (NP) in the bbar -> sbar c cbar decay. If so, the value of beta_s is
different than for the case in which NP is assumed to be present only in the
mixing. We have examined several models of NP and found that, indeed, there can
be significant contributions to the decay. These effects are consistent with
measurements in B -> J/psi K* and Bd -> J/psi Ks. Due to the NP in the decay,
polarization-dependent indirect CP asymmetries and triple-product asymmetries
are predicted in Bs -> J/psi phi.Comment: 28 pages, JHEP, no figures. Considerable changes made. Abstract and
main text of paper modified to alter presentation. Appendix added. References
added. Conclusions unchanged
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