11,456 research outputs found
Positronium Decay : Gauge Invariance and Analyticity
The construction of positronium decay amplitudes is handled through the use
of dispersion relations. In this way, emphasis is put on basic QED principles:
gauge invariance and soft-photon limits (analyticity).
A firm grounding is given to the factorization approaches, and some
ambiguities in the spin and energy structures of the positronium wavefunction
are removed. Non-factorizable amplitudes are naturally introduced. Their
dynamics is described, especially regarding the enforcement of gauge invariance
and analyticity through delicate interferences. The important question of the
completeness of the present theoretical predictions for the decay rates is then
addressed. Indeed, some of those non-factorizable contributions are unaccounted
for by NRQED analyses. However, it is shown that such new contributions are
highly suppressed, being of order alpha^3.
Finally, a particular effective form factor formalism is constructed for
parapositronium, allowing a thorough analysis of binding energy effects and
analyticity implementation.Comment: 34 pages, 13 figure
Does ozonation enhance activated carbon adsorption of PFAS in textile wastewater?
Per- and polyfluoroalkyl substances (PFAS) are used in numerous industrial applications, such as in textile manufacturing, because of their special chemical properties. To avoid PFAS spread in the environment, removal strategies need to be implemented at the wastewater treatment plants (WWTP) to reduce their environmental risk on receiving water bodies. The fate of 14 PFAS in a full-scale WWTP treating textile and civil wastewater (WW) was investigated. The addition of an adsorption step before or after the ozonation process was studied through adsorption isotherms tested on the WW collected before and after the full-scale ozonation step. Ozonation is not aimed at PFAS removing, but it lowers organic matter competition towards long-chain PFAS in the following adsorption step. The removal of UVA254 seems to be a good proxy variable for PFAS adsorption, with relationships not dependent on the presence of ozonation step
Sound velocity and absorption measurements under high pressure using picosecond ultrasonics in diamond anvil cell. Application to the stability study of AlPdMn
We report an innovative high pressure method combining the diamond anvil cell
device with the technique of picosecond ultrasonics. Such an approach allows to
accurately measure sound velocity and attenuation of solids and liquids under
pressure of tens of GPa, overcoming all the drawbacks of traditional
techniques. The power of this new experimental technique is demonstrated in
studies of lattice dynamics, stability domain and relaxation process in a
metallic sample, a perfect single-grain AlPdMn quasicrystal, and rare gas, neon
and argon. Application to the study of defect-induced lattice stability in
AlPdMn up to 30 GPa is proposed. The present work has potential for application
in areas ranging from fundamental problems in physics of solid and liquid
state, which in turn could be beneficial for various other scientific fields as
Earth and planetary science or material research
An evaluation of |Vus| and precise tests of the Standard Model from world data on leptonic and semileptonic kaon decays
We present a global analysis of leptonic and semileptonic kaon decay data,
including all recent results published by the BNL-E865, KLOE, KTeV, ISTRA+ and
NA48 experiments. This analysis, in conjunction with precise lattice
calculations of the hadronic matrix elements now available, leads to a very
precise determination of |Vus| and allows us to perform several stringent tests
of the Standard Model.Comment: LaTeX, 25 pages, 12 figures, 16 tables. Submitted to EPJC. v2: Minor
changes for accepted version. No numerical results change
Adsorption on activated carbon for PFAS removal: should we act at the source or before the discharge into the environment?
Per- and polyfluoroalkyl substances (PFAS), used in several industrial applications, such as textile production, are gaining increasing concern due to their spread in the environment, their stability and eco-toxicity. To avoid PFAS spread in the environment, removal strategies need to be implemented at both industrial and municipal wastewater treatment plants (WWTP). This study presents a case study in a textile district in northern Italy where PFAS removal in wastewater (WW) through adsorption on activated carbon was tested at lab and pilot-scale at different points of the system (textile companies and municipal WW treatment plant). This lab-testing was proved to be useful to identify where to apply such process in the system and to optimize process configuration and operating conditions
Two Gallium data sets, spin flavour precession and KamLAND
We reexamine the possibility of a time modulation of the low energy solar
neutrino flux which is suggested by the average decrease of the Ga data in line
with our previous arguments. We perform two separate fits to the solar neutrino
data, one corresponding to 'high' and the other to 'low' Ga data, associated
with low and high solar activity respectively. We therefore consider an
alternative to the conventional solar+KamLAND fitting, which allows one to
explore the much wider range of the angle permitted by the
KamLAND fitting alone. We find a solution with parameters in which the 'high' and
the 'low' Ga rates lie far apart and are close to their central values and is
of comparable quality to the global best fit, where these rates lie much closer
to each other. This is an indication that the best fit in which all solar and
KamLAND data are used is not a good measure of the separation of the two Ga
data sets, as the information from the low energy neutrino modulation is
dissimulated in the wealth of data. Furthermore for the parameter set proposed
one obtains an equally good fit to the KamLAND energy spectrum and an even
better fit than the 'conventional' LMA one for the reactor antineutrino
survival probability as measured by KamLAND.Comment: V2: 15 pages, 3 eps figures, fit improved, final version to appear in
Journal of Physics
Drinking water recontamination in distribution networks: the case of bisphenol A release from epoxy resins
Monitoring and management of drinking water distribution networks (DWDNs), including possible release from materials in contact with drinking water (DW), have been stressed as crucial to avoid DW re-contamination leading to a potential increase of human health risk. Recent scientific studies and regulations clearly highlighted the release of bisphenol A (BPA) from plastic materials used to renovate DWDNs pipelines as one the major hazardous events. Lab tests on three epoxy resins were designed with the Design of Experiments (DoE) method to calibrate a migration model. In order to predict water quality variation in DWDNs, the migration model was combined with a hydraulic model, through EPANET-MSX, and validated in relevant environmental conditions, in collaboration with an Italian water utility. The model allowed to simulate BPA propagation in the DWDN identifying the most vulnerable areas and permitting to customize a site-specific monitoring and intervention plan to minimize the risk
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