2,844 research outputs found
The non-standard model Higgs
This is the write-up of the talk presented at the XXV Rencontres de Physique de La Valle d’Aoste (La Thuile), aimed to introduce the ideas of Composite Higgs Models to an experimental audience. We review the basic features of theories where the Higgs is a composite state and its phenomenological consequences at LHC. We also emphasize the possibility of a heavy Higgs which could provide a first
experimental hint on this type of models
Pericentromeric organization at the fusion point of mouse Robertsonian translocation chromosomes
In mammals, Robertsonian (Rb) translocation (the joining of two telo/acrocentric chromosomes at their centromere to form a metacentric) is the most effective process in chromosomal evolution leading to speciation; its occurrence also affects human health (through the induction of trisomies) and the fertility of farm animals. To understand the mechanism of Rb translocation, we used the house mouse as a model system and studied the organization of pericentromeric satellite DNAs (satDNA) of telocentrics and Rb chromosomes, both minor and major satDNA. The chromosome-orientation fluorescence in situ hybridization (CO-FISH) technique was used to analyze the major satDNA. To detect the very small amount of minor satDNA, a procedure was developed that combines CO-FISH with primed in situ labeling and conventional FISH and is five times more sensitive than the CO-FISH procedure alone. It was found that both the major and the minor satDNA tandem repeats are oriented head-to-tail in telocentric and Rb chromosomes, and their polarity is always the same relative to the centromere. We suggest that all tandemly repetitive satDNAs in a species probably are locked into such a symmetry constraint as a universal consequence of chromosomal evolution. Rb translocation breakpoints were found localized within the minor satDNA of telocentrics, and these sequences contributed symmetrically to the formation of the centromeric region of the Rb chromosomes. These results are important for an understanding of the geometry of Rb translocations and suggest the study of DNA orientation as a new tool for investigating these rearrangements
Beautiful and damned. Combined effect of content quality and social ties on user engagement
User participation in online communities is driven by the intertwinement of
the social network structure with the crowd-generated content that flows along
its links. These aspects are rarely explored jointly and at scale. By looking
at how users generate and access pictures of varying beauty on Flickr, we
investigate how the production of quality impacts the dynamics of online social
systems. We develop a deep learning computer vision model to score images
according to their aesthetic value and we validate its output through
crowdsourcing. By applying it to over 15B Flickr photos, we study for the first
time how image beauty is distributed over a large-scale social system.
Beautiful images are evenly distributed in the network, although only a small
core of people get social recognition for them. To study the impact of exposure
to quality on user engagement, we set up matching experiments aimed at
detecting causality from observational data. Exposure to beauty is
double-edged: following people who produce high-quality content increases one's
probability of uploading better photos; however, an excessive imbalance between
the quality generated by a user and the user's neighbors leads to a decline in
engagement. Our analysis has practical implications for improving link
recommender systems.Comment: 13 pages, 12 figures, final version published in IEEE Transactions on
Knowledge and Data Engineering (Volume: PP, Issue: 99
Phenomenology of 10^32 Dark Sectors
We postulate an exact permutation symmetry acting on 10^32 Standard Model
copies as the largest possible symmetry extension of the Standard Model. This
setup automatically lowers the fundamental gravity cutoff down to TeV, and
thus, accounts for the quantum stability of the weak scale. We study the
phenomenology of this framework and show that below TeV energies the copies are
well hidden, obeying all the existing observational bounds. Nevertheless, we
identify a potential low energy window into the hidden world, the oscillation
of the neutron into its dark copies. At the same time, proton decay can be
suppressed by gauging the diagonal baryon number of the different copies. This
framework offers an alternative approach to several particle physics questions.
For example, we suggest a novel mechanism for generating naturally small
neutrino masses that are suppressed by the number of neutrino species. The
mirror copies of the Standard Model naturally house dark matter candidates. The
general experimentally observable prediction of this scenario is an emergence
of strong gravitational effects at the LHC. The low energy permutation symmetry
powerfully constrains the form of this new gravitational physics and allows to
make observational predictions, such as, production of micro black-holes with
very peculiar properties.Comment: 36 pages. v2, note added on oscillation of neutral state, Refs. adde
Radion effective theory in the detuned Randall-Sundrum model
We compute the two-derivative low-energy effective action for the radion in
the (supersymmetric) Randall-Sundrum scenario with detuned brane tensions. At
the classical level, a potential automatically stabilizes the distance between
the branes. In the supersymmetric case, supersymmetry can be broken
spontaneously by a vacuum expectation value for the fifth component of the
graviphoton.Comment: 17 pages. JHEP class. New Appendix. Published versio
Composite MFV and Beyond
We revisit and extend realizations of Minimal Flavor Violation (MFV) in
theories with strongly coupled electro-weak symmetry breaking. MFV requires
that some chiralities of light SM quarks are strongly composite leading,
depending on the scenario, to bounds from compositeness searches, precision
electro-weak tests or even flavor physics. Within the framework of partial
compositeness we show how to extend the MFV paradigm allowing the treat the top
quark differently. This can be realized if for example the strong sector has an
U(2) symmetry. In this case the light generations can be mostly elementary and
all the bounds are easily satisfied.Comment: 16 pages. v2) estimates improved, conclusions unchange
Modelling human factors in perceptual multimedia quality: On the role of personality and culture
Perception of multimedia quality is shaped by a rich interplay between system, context, and human factors. While system and context factors are widely researched, few studies in this area consider human factors as sources of systematic variance. This paper presents an analysis on the influence of personality (Five-Factor Model) and cultural traits (Hofstede Model) on the perception of multimedia quality. A set of 144 video sequences (from 12 short movie excerpts) were rated by 114 participants from a cross-cultural population, producing 1232 ratings. On this data, three models are compared: a baseline model that only considers system factors; an extended model that includes personality and culture as human factors; and an optimistic model in which each participant is modeled as a random effect. An analysis shows that personality and cultural traits represent 9.3% of the variance attributable to human factors while human factors overall predict an equal or higher proportion of variance compared to system factors. In addition, the quality-enjoyment correlation varied across the movie excerpts. This suggests that human factors play an important role in perceptual multimedia quality, but further research to explore moderation effects and a broader range of human factors is warranted
Footballs, Conical Singularities and the Liouville Equation
We generalize the football shaped extra dimensions scenario to an arbitrary
number of branes. The problem is related to the solution of the Liouville
equation with singularities and explicit solutions are presented for the case
of three branes. The tensions of the branes do not need to be tuned with each
other but only satisfy mild global constraints.Comment: 15 pages, Refs. added, minor changes. Typo in eq. 4.3 corrected.
Version to be published in PR
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