5,399 research outputs found
Majorana Physics Through the Cabibbo Haze
We present a model in which the Supersymmetric Standard Model is augmented by
the family symmetry \bs{\m Z_7 \rtimes \m Z_3}. Motivated by , where
the charge two-thirds and neutral Dirac Yukawa matrices are related, we
propose, using family symmetry, a special form for the seesaw Majorana matrix;
it contains a squared correlated hierarchy, allowing it to mitigate the severe
hierarchy of the quark sector. It is reproduced naturally by the invariant
operators of \bs{\m Z_7 \rtimes \m Z_3}, with the hierarchy carried by
familon fields. In addition to relating the hierarchy of the to the sector, it contains a Gatto-Sartori-Tonin
like relation, predicts a normal hierarchy for Tri-bimaximal and Golden Ratio
mixings, and gives specific values for the light neutrino masses.Comment: 33 pages, 1 figure. This revised version omits a section where a
particular linear combination of dimension-five operators was mistakenly
claimed to produce the special form of the Majorana matrix. The main changes
are to the Introduction, Sec. 5.1 of the previous version, and Summary and
Conclusions. In addition to minor changes throughout, we have corrected an
erroneous sign in Eq. 1
On Mixing Supersymmetry and Family Symmetry Breakings
We present a toy model in which the Higgs sector fields transform as
non-Abelian representations of a family symmetry group, and consider the
possibility that the extra family partners of the Higgs particles act as
messengers for both supersymmetry and family symmetry breakings. Although such
mediation schemes generically produce family dependent soft supersymmetry
breaking terms at the messenger scale, we demonstrate the existence of a
focusing mechanism which may erase such hierarchies through renormalization
group running.Comment: 38 Pages, 11 Figures. Updated file to include minor changes, update
figures, and to correct errors in Eq. 4.15. An error was found in the first
version soft masses (Eq.4.15), however the conclusions of the paper are
unaffected. We have included the Journal reference and DO
Non-linear photochemical pathways in laser induced atmospheric aerosol formation
We measured the chemical composition and the size distribution of aerosols
generated by femtosecond-Terawatt laser pulses in the atmosphere using an
aerosol mass spectrometer (AMS). We show that nitric acid condenses in the form
of ammonium nitrate, and that oxidized volatile organics also contribute to
particle growth. These two components account for two thirds and one third,
respectively, of the dry laser-condensed mass. They appear in two different
modes centred at 380 nm and 150 nm. The number concentration of particles
between 25 and 300 nm increases by a factor of 15. Pre-existing water droplets
strongly increase the oxidative properties of the laser-activated atmosphere,
substantially enhancing the condensation of organics under laser illumination.Comment: 19 pages, 5 figure
Neural network tracking and extension of positive tracking periods
Feature detectors have been considered for the role of supplying additional information to a neural network tracker. The feature detector focuses on areas of the image with significant information. Basically, if a picture says a thousand words, the feature detectors are looking for the key phrases (keypoints). These keypoints are rotationally invariant and may be matched across frames. Application of these advanced feature detectors to the neural network tracking system at JPL has promising potential. As part of an ongoing program, an advanced feature detector was tested for augmentation of a neural network based tracker. The advance feature detector extended tracking periods in test sequences including aircraft tracking, rover tracking, and simulated Martian landing. Future directions of research are also discussed
Why practice philosophy as a way of life?
This essay explains why there are good reasons to practice philosophy as a way of life. The argument begins with the assumption that we should live well but that our understanding of how to live well can be mistaken. Philosophical reason and reflection can help correct these mistakes. Nonetheless, the evidence suggests that philosophical reasoning often fails to change our dispositions and behavior. Drawing on the work of Pierre Hadot, the essay claims that spiritual exercises and communal engagement mitigate the factors that prevent us from living in accord- ance with our conceptions of the good life. So, many of us have reasons to engage in philosophical reasoning along with behavioral, cognitive, and social strategies to alter our behavior and attitudes so that they’re in line with our philosophical commitments. In these respects, many of us should practice philosophy as a way of life
Hubble Space Telescope Astrometry of the Procyon System
The nearby star Procyon is a visual binary containing the F5 IV-V subgiant
Procyon A, orbited in a 40.84 yr period by the faint DQZ white dwarf Procyon B.
Using images obtained over two decades with the Hubble Space Telescope, and
historical measurements back to the 19th century, we have determined precise
orbital elements. Combined with measurements of the parallax and the motion of
the A component, these elements yield dynamical masses of 1.478 +/- 0.012 Msun
and 0.592 +/- 0.006 Msun for A and B, respectively.
The mass of Procyon A agrees well with theoretical predictions based on
asteroseismology and its temperature and luminosity. Use of a standard
core-overshoot model agrees best for a surprisingly high amount of core
overshoot. Under these modeling assumptions, Procyon A's age is ~2.7 Gyr.
Procyon B's location in the H-R diagram is in excellent agreement with
theoretical cooling tracks for white dwarfs of its dynamical mass. Its position
in the mass-radius plane is also consistent with theory, assuming a
carbon-oxygen core and a helium-dominated atmosphere. Its progenitor's mass was
1.9-2.2 Msun, depending on its amount of core overshoot.
Several astrophysical puzzles remain. In the progenitor system, the stars at
periastron were separated by only ~5 AU, which might have led to tidal
interactions and even mass transfer; yet there is no direct evidence that these
have occurred. Moreover the orbital eccentricity has remained high (~0.40). The
mass of Procyon B is somewhat lower than anticipated from the
initial-to-final-mass relation seen in open clusters. The presence of heavy
elements in its atmosphere requires ongoing accretion, but the place of origin
is uncertain.Comment: Accepted by Astrophysical Journa
STATE OF THE ART AND RESEARCH PRIORITIES IN HYDROGEN SAFETY
Wide spread deployment and use of hydrogen and fuel cell technologies can occur only if hydrogen safety issues have been addressed in order to ensure that hydrogen fuel presents the same or lower level of hazards and associated risk compared to conventional fuel technologies. To achieve this goal, hydrogen safety research should be directed to address the remaining knowledge gaps using risk-informed approaches to develop engineering solutions and Regulation Codes and Standards (RCS) requirements that meet individual and societal risk acceptance criteria, yet are cost-effective and market-competitive. IA HySafe and JRC IET partnered to organize a Research Priorities Workshop in Berlin on October 16-17, 2012 hosted by BAM (on behalf of IA HySafe) to address knowledge gaps in CFD modelling of hydrogen safety issues. The findings of the workshop are described in the report. The document aims to become a reference document for researchers/scientists and technical (including industry) experts working in the area worldwide. It is also a welcomed contribution for the Fuel Cell and Hydrogen Joint Undertaking (FCH JU) and for other funding bodies/organizations that must make decisions on research programmes and during the selection/choice of projects to be financially supported pursuing the safe use of hydrogen within Horizon 2020 framework.JRC.F.2-Energy Conversion and Storage Technologie
‘We are labeled as gang members, even though we are not’: belonging, aspirations and social mobility in Cartagena
This paper explores how belonging and aspirations interact to shape marginalized young Colombians’ strategies for upward social mobility. Recent literature has argued that in the context of inequality and poverty, social mobility is constrained by people’s inability to aspire to and/or achieve their aspirations. The majority of this literature is from the economics field and looks at the way poverty acts as a brake on social mobility. This paper provides an additional interdisciplinary analysis of the role of ‘belonging’ (to places and social class) in influencing aspirations of young Colombians. Findings are based on ethnographic fieldwork with young people from two marginalized neighborhoods in Cartagena. It is argued that aspirations are closely linked to belonging and the extent to which young people feel integral to or distanced from their localities. Using a Bourdieusian perspective, the paper examines how belonging is developed and how it influences behavior, orientations and future prospects. This approach generates insights into young people’s apparent low aspirations beyond the explanation of internal behavioral poverty traps. In so doing, it provides a more comprehensive understanding of how societal structures limit aspiration development and achievement
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