1,545 research outputs found
Dark matter and spin-1 milli-charged particles
New physics scenarios beyond the Standard Model predict the existence of
milli-charged particles. So far, only spin-1/2 and spin-0 milli-charged
particles have been considered in literature, leaving out the interesting case
of spin-1. We propose a minimal unitary and renormalizable model of massive
milli-charged vector particles. Unitarity requires that these particles are
gauge bosons of a non-abelian spontaneously broken gauge symmetry. The minimal
scenario then consists of an extended Standard Model gauge group together with a dark Higgs boson
responsible for the symmetry breaking in the dark sector. By imposing that the
dark Higgs multiplet has a non-vanishing milli-hypercharge, stable
milli-charged spin-1 fields arise thereby providing a potential dark matter
candidate. We analyse the phenomenological constraints on this scenario and
discuss their implications.Comment: Matches the version that is to appear on JHE
Polarization observables for millicharged particles in photon collisions
Particles in a hidden sector can potentially acquire a small electric charge
through their interaction with the Standard Model and can consequently be
observed as millicharged particles. We systematically compute the production of
millicharged scalar, fermion and vector boson particles in collisions of
polarized photons. The presented calculation is model independent and is based
purely on the assumptions of electromagnetic gauge invariance and unitarity.
Polarization observables are evaluated and analyzed for each spin case. We show
that the photon polarization asymmetries are a useful tool for discriminating
between the spins of the produced millicharged particles. Phenomenological
implications for searches of millicharged particles in dedicated photon-photon
collision experiments are also discussed.Comment: 11 pages, 7 figures, Appendix added, same as published versio
One loop Standard Model corrections to flavor diagonal fermion-graviton vertices
We extend a previous analysis of flavor-changing fermion-graviton vertices,
by adding the one-loop SM corrections to the flavor diagonal fermion-graviton
interactions. Explicit analytical expressions taking into account fermion
masses for the on-shell form factors are computed and presented. The infrared
safety of the fermion-graviton vertices against radiative corrections of soft
photons and gluons is proved, by extending the ordinary infrared cancellation
mechanism between real and virtual emissions to the gravity case. These results
can be easily generalized to fermion couplings with massive gravitons,
graviscalar, and dilaton fields, with potential phenomenological implications
to new physics scenarios with low gravity scale.Comment: 30 pages, 11 figures, revised final version, to appear on Phys. Rev.
An analytical framework to nowcast well-being using mobile phone data
An intriguing open question is whether measurements made on Big Data
recording human activities can yield us high-fidelity proxies of socio-economic
development and well-being. Can we monitor and predict the socio-economic
development of a territory just by observing the behavior of its inhabitants
through the lens of Big Data? In this paper, we design a data-driven analytical
framework that uses mobility measures and social measures extracted from mobile
phone data to estimate indicators for socio-economic development and
well-being. We discover that the diversity of mobility, defined in terms of
entropy of the individual users' trajectories, exhibits (i) significant
correlation with two different socio-economic indicators and (ii) the highest
importance in predictive models built to predict the socio-economic indicators.
Our analytical framework opens an interesting perspective to study human
behavior through the lens of Big Data by means of new statistical indicators
that quantify and possibly "nowcast" the well-being and the socio-economic
development of a territory
Anomalous Higgs-boson coupling effects in HWW production at the LHC
We study the LHC associated production of a Higgs boson and a W^+W^-
vector-boson pair at 14 TeV, in the Standard Model and beyond. We consider
different signatures corresponding to the cleanest H and W decay channels, and
discuss the potential of the high-luminosity phase of the LHC. In particular,
we investigate the sensitivity of the HWW production to possible anomalous
Higgs couplings to vector bosons and fermions. Since the b-quark initiated
partonic channel contributes significantly to this process, we find a moderate
sensitivity to both the size and sign of an anomalous top-quark Yukawa
coupling, because perturbative unitarity in the standard model implies a
destructive interference in the b b-bar subprocess. We show that a combination
of various signatures can reach a ~9 standard-deviation sensitivity in the
presently allowed negative region of the top-Higgs coupling, if not previously
excluded.Comment: 13 pages, 3 figure
Nanoparticle-based receptors mimic protein-ligand recognition
The self-assembly of a monolayer of ligands on the surface of noble metal nanoparticles dictates the fundamental nanoparticle\u2019s behavior and its functionality. In this combined computational\u2013experimental study, we analyze the structure, organization, and dynamics of functionalized coating thiols in monolayer-protected gold nanoparticles (AuNPs). We explain how functionalized coating thiols self-organize through a delicate and somehow counterintuitive balance of interactions within the monolayer itself and with the solvent. We further describe how the nature and plasticity of these interactions modulate nanoparticle-based chemosensing. Importantly, we found that self-organization of coating thiols can induce the formation of binding pockets in AuNPs. These transient cavities can accommodate small molecules, mimicking protein-ligand recognition, which may explain the selectivity and sensitivity observed for different organic analytes in NMR chemosensing experiments. Thus, our findings advocate for the rational design of tailored coating groups to form specific recognition binding sites on monolayer-protected AuNPs
Mass Corrections to Flavor-Changing Fermion-Graviton Vertices in the Standard Model
In a previous study, the flavor-changing fermion-graviton interactions have
been analyzed in the framework of the standard model, where analytical results
for the relevant form factors were obtained at the leading order in the
external fermion masses. These interactions arise at one-loop level by the
charged electroweak corrections to the fermion-graviton vertex, when the
off-diagonal flavor transitions in the corresponding charged weak currents are
taken into account. Due to the conservation of the energy-momentum tensor, the
corresponding form factors turn out to be finite and gauge invariant when
external fermions are on-shell. Here we extend this previous analysis by
including the exact dependence on the external fermion masses. Complete
analytical results are provided for all the relevant form factors to the
flavor-changing fermion-graviton transitions.Comment: 19 pages, 9 figure
Mesh Fixation Methods in Groin Hernia Surgery
No unanimous consent has been reached by surgeons in terms of a method for mesh fixation in laparoscopic and open surgery for inguinal hernia repair. Many different methods of fixation are available, and the choice of which one to use is still based on surgeons’ preferences. At present, tissue glues, sutures, and laparoscopic tacks are the most common fixating methods. In open technique, sutures have been the method of choice for their reduced costs and surgeons’ habits. Nevertheless, tissue glues have been demonstrated to be effective and safe. Similarly, tacks can be considered the most common means of fixation in laparoscopic hernia repair, but they are connected to a higher risk of complication and morbidity. In this chapter, we present these types of mesh fixation, their characteristics and potential risks, and advantages of their use
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