101 research outputs found
Modulated Inflation
We have studied modulated inflation that generates curvature perturbation
from light-field fluctuation. As discussed in previous works, even if the
fluctuation of the inflaton itself does not generate the curvature perturbation
at the horizon crossing, fluctuation of a light field may induce fluctuation
for the end-line of inflation and this may lead to generation of cosmological
perturbation ``at the end of the inflation''. Our scenario is different from
those that are based on the fluctuations of the boundary of the inflaton
trajectory, as clearly explained in this paper by using the
formalism. In this paper, we will consider the perturbation of the inflaton
velocity that can be induced by a light field other than the inflaton. We also
explain the crucial difference from the standard multi-field inflation model.
We show concrete examples of the modulated inflation scenario in which
non-gaussianity can be generated. We also discuss the running of the
non-gaussianity parameter.Comment: 17pages, k^2/a^2 is included, accepted for publication in PL
Formation of Highly Oxygenated Organic Molecules from alpha-Pinene Ozonolysis : Chemical Characteristics, Mechanism, and Kinetic Model Development
Terpenes are emitted by vegetation, and their oxidation in the atmosphere is an important source of secondary organic aerosol (SOA). A part of this oxidation can proceed through an autoxidation process, yielding highly oxygenated organic molecules (HOMs) with low saturation vapor pressure. They can therefore contribute, even in the absence of sulfuric acid, to new particle formation (NPF). The understanding of the autoxidation mechanism and its kinetics is still far from complete. Here, we present a mechanistic and kinetic analysis of mass spectrometry data from α-pinene (AP) ozonolysis experiments performed during the CLOUD 8 campaign at CERN. We grouped HOMs in classes according to their identified chemical composition and investigated the relative changes of these groups and their components as a function of the reagent concentration. We determined reaction rate constants for the different HOM peroxy radical reaction pathways. The accretion reaction between HOM peroxy radicals was found to be extremely fast. We developed a pseudo-mechanism for HOM formation and added it to the AP oxidation scheme of the Master Chemical Mechanism (MCM). With this extended model, the observed concentrations and trends in HOM formation were successfully simulated.Peer reviewe
Delta-N formalism for the evolution of the curvature perturbations in generalized multi-field inflation
The delta-N formalism is considered to calculate the evolution of the
curvature perturbation in generalized multi-field inflation models. The result
is consistent with the usual calculation of the standard kinetic term. For the
calculation of the generalized kinetic term, we improved the definition of the
adiabatic field. Our calculation improves the usual calculation of the
evolution of the curvature perturbations based on the field equations and the
perturbations, giving a very simple and intuitive argument for the evolution
equations in terms of the perturbations of the inflaton velocity. Significance
of non-equilibrium corrections are also discussed, which is caused by the
small-scale (decaying) inhomogeneities. This formalism based on the modulated
inflation scenario (i.e., calculation based on the perturbations related to the
inflaton velocity) provides a powerful tool for investigating the signature of
moduli that may appear in string theory.Comment: 24 pages, latex2e, 1 figure, added comment for inflation with a step
on the potential, accepted for publication in PL
European Sourcebook of Crime and Criminal Justice Statistics 2014
This is the fifth edition of a data collection initiative that started in 1993 under the umbrella of the Council of Europe. As was the case with the earlier editions, it was prepared by an international group of experts, who have recently formed a legal entity called European Sourcebook of Criminal Justice e.V.. The format developed during the earlier editions was maintained, especially the network of national correspondents and regional coordinators whose contribution has, once more, been decisive in collecting and validating data on a variety of subjects from 41 countries. New categories for the collection of data on community sanctions and measures and probation agencies were introduced with the support of the Confederation of European Probation (CEP). In addition, the chapter on victimization surveys for the first time refers to national studies, as no recent international survey was available. The present document covers the years 2007 to 2011 for police, prosecution, conviction and prison statistics, with detailed analyses for 2010
Remote Inflation as hybrid-like sneutrino/MSSM inflation
A new scenario of hybrid-like inflation is considered for sneutrino and MSSM
fields. Contrary to the usual hybrid inflation model, the direct coupling
between a trigger field and the sneutrino/MSSM inflaton field is not necessary
for the scenario. The dissipation and the radiation from the sneutrino/MSSM
inflaton can be written explicitly by using the Yukawa couplings. Remote
inflation does not require the shift symmetry or cancellation in solving the
eta-problem.Comment: 27pages, added 1 figure and 2 appendices, accepted for publication in
NP
Experimental particle formation rates spanning tropospheric sulfuric acid and ammonia abundances, ion production rates, and temperatures
Binary nucleation of sulfuric acid and water as well as ternary nucleation involving ammonia are thought to be the dominant processes responsible for new particle formation (NPF) in the cold temperatures of the middle and upper troposphere. Ions are also thought to be important for particle nucleation in these regions. However, global models presently lack experimentally measured NPF rates under controlled laboratory conditions and so at present must rely on theoretical or empirical parameterizations. Here with data obtained in the European Organization for Nuclear Research CLOUD (Cosmics Leaving OUtdoor Droplets) chamber, we present the first experimental survey of NPF rates spanning free tropospheric conditions. The conditions during nucleation cover a temperature range from 208 to 298K, sulfuric acid concentrations between 5x10(5) and 1x10(9)cm(-3), and ammonia mixing ratios from zero added ammonia, i.e., nominally pure binary, to a maximum of -1400 parts per trillion by volume (pptv). We performed nucleation studies under pure neutral conditions with zero ions being present in the chamber and at ionization rates of up to 75ion pairs cm(-3)s(-1) to study neutral and ion-induced nucleation. We found that the contribution from ion-induced nucleation is small at temperatures between 208 and 248K when ammonia is present at several pptv or higher. However, the presence of charges significantly enhances the nucleation rates, especially at 248K with zero added ammonia, and for higher temperatures independent of NH3 levels. We compare these experimental data with calculated cluster formation rates from the Atmospheric Cluster Dynamics Code with cluster evaporation rates obtained from quantum chemistry.Peer reviewe
Observation of viscosity transition in alpha-pinene secondary organic aerosol
Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the Cosmics Leaving Outdoor Droplets (CLOUD) experiment at The European Organisation for Nuclear Research (CERN), we deployed a new in situ optical method to detect the viscous state of alpha-pinene SOA particles and measured their transition from the amorphous highly viscous state to states of lower viscosity. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical particles at relative humidities near the deliquescence point. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to a spherical shape was observed as the RH was increased to between 35aEuro-% at -10aEuro-A degrees C and 80aEuro-% at -38aEuro-A degrees C, confirming previous calculations of the viscosity-transition conditions. Consequently, alpha-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical, and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere.Peer reviewe
Observation of viscosity transition in α-pinene secondary organic aerosol
Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the CLOUD experiment at CERN, we deployed a new in-situ optical method to detect the viscosity of α-pinene SOA particles and measured their transition from the amorphous viscous to liquid state. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical liquid particles during deliquescence. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to spherical shape was observed as the RH was increased to between 35 % at â10 °C and 80 % at â38 °C, confirming previous calculations of the viscosity transition conditions. Consequently, α-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere
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