8,564 research outputs found
Precision Measurements of Higgs Couplings: Implications for New Physics Scales
The measured properties of the recently discovered Higgs boson are in good
agreement with predictions from the Standard Model. However, small deviations
in the Higgs couplings may manifest themselves once the currently large
uncertainties will be improved as part of the LHC program and at a future Higgs
factory. We review typical new physics scenarios that lead to observable
modifications of the Higgs interactions. They can be divided into two broad
categories: mixing effects as in portal models or extended Higgs sectors, and
vertex loop effects from new matter or gauge fields. In each model we relate
coupling deviations to their effective new physics scale. It turns out that
with percent level precision the Higgs couplings will be sensitive to the
multi-TeV regime.Comment: Invited review for Journal of Physics G, 33pp; v2: references added
and improved discussion of operator basis in section 2.
Resonance Propagation and Threshold Singularities
We consider the problem of propagation of an unstable particle in the
framework of Quantum Field Theory. Using unitarity, we show that a real
renormalization constant free of threshold singularities naturally arises.Comment: 5 pages, no figures, revte
Bosonic Seesaw in the Unparticle Physics
Recently, conceptually new physics beyond the Standard Model has been
proposed by Georgi, where a new physics sector becomes conformal and provides
"unparticle" which couples to the Standard Model sector through higher
dimensional operators in low energy effective theory. Among several
possibilities, we focus on operators involving the (scalar) unparticle, Higgs
and the gauge bosons. Once the Higgs develops the vacuum expectation value
(VEV), the conformal symmetry is broken and as a result, the mixing between the
unparticle and the Higgs boson emerges. In this paper, we consider a natural
realization of bosonic seesaw in the context of unparticle physics. In this
framework, the negative mass squared or the electroweak symmetry breaking
vacuum is achieved as a result of mass matrix diagonalization. In the
diagonalization process, it is important to have zero value in the
(1,1)-element of the mass matrix. In fact, the conformal invariance in the
hidden sector can actually assure the zero of that element. So, the bosonic
seesaw mechanism for the electroweak symmetry breaking can naturally be
understood in the framework of unparticle physics.Comment: 5 pages, no figure; added one more referenc
Determining Heavy Mass Parameters in Supersymmetric SO(10) Models
Extrapolations of soft scalar mass parameters in supersymmetric theories can
be used to explore elements of the physics scenario near the grand unification
scale. We investigate the potential of this method in the lepton sector of
SO(10) which incorporates right-handed neutrino superfields. The method is
exemplified in two models by exploring limits on the precision that can be
expected from coherent LHC and e+e- collider analyses in the reconstruction of
the fundamental scalar mass parameters at the unification scale and of the
D-terms related to the breaking of grand unification symmetries. In addition,
the mass of the third-generation right-handed neutrino can be estimated in
seesaw scenarios. Even though the models are simplified and not intended to
account for all aspects of a final comprehensive SO(10) theory, they provide
nevertheless a valid base for identifying essential elements that can be
inferred on the fundamental high-scale theory from high-energy experiments.Comment: 26 pp LaTeX; version published in Phys. Rev.
Two methods for constructing a gene ontology-based feature network for a Bayesian network classifier and applications to datasets of aging-related genes.
In the context of the classification task of data mining or machine learning, hierarchical feature selection methods exploit hierarchical relationships among features in order to select a subset of features without hierarchical redundancy. Hierarchical feature selection is a new research area in classification research, since nearly all feature selection methods ignore hierarchical relationships among features. This paper proposes two methods for constructing a network of features to be used by a Bayesian Network Augmented Naïve Bayes (BAN) classifier, in datasets of aging-related genes where Gene Ontology (GO) terms are used as hierarchically related predictive features. One of the BAN network construction method relies on a hierarchical feature selection method to detect and remove hierarchical redundancies among features (GO terms); whilst the other BAN network construction method simply uses a conventional, flat feature selection method to select features, without removing the hierarchical redundancies associated with the GO. Both BAN network construction methods may create new edges among nodes (features) in the BAN network that did not exist in the original GO DAG (Directed Acyclic Graph), in order to preserve the generalization-specialization (ancestor-descendant) relationship among selected features. Experiments comparing these two BAN network construction methods, when using two different hierarchical feature selection methods and one at feature selection method, have shown that the best results are obtained by the BAN network construction method using one type of hierarchical feature selection method, i.e., select Hierarchical Information-Preserving features (HIP)
Determining Sneutrino Masses and Physical Implications
In some areas of supersymmetry parameter space, sneutrinos are lighter than
the charginos and the next-to-lightest neutralino, and they decay into the
invisible neutrino plus lightest-neutralino channel with probability one. In
such a scenario they can be searched for in decays of charginos that are
pair-produced in e+e- collisions, and in associated sneutrino-chargino
production in photon-electron collisions. The sneutrino properties can be
determined with high accuracy from the edges of the decay energy spectra in the
first case and from threshold scans in the second. In the final part of the
report we investigate the mass difference of sneutrinos and charged sleptons
between the third and the first two generations in seesaw-type models of the
neutrino/sneutrino sector. For a wide range these mass differences are
sensitive to the seesaw scale.Comment: 20 p
Acquired-Transient Factor X Deficiency in a Teenager with Extensive Burns
Acquired factor X deficiency is an extremely rare situation. It has shown to be associated with systemic amyloidosis, respiratory mycoplasma infection, factor X inhibitors, antiphospholipid antibodies, vitamin K defi ciency/liver disease as well as the use of certain medications
(meropenem, valproic acid). The pathogenesis and transient nature of this deficit remain poorly understood. The authors describe the case of a teenager hospitalised for extensive burns that developed active bleeding after removal of central venous catheter. He was diagnosed with transient factor X deficiency. Normalisation of coagulation status and factor X levels occurred spontaneously 10 days after the bleeding episode
Weakly coupled neutral gauge bosons at future linear colliders
A weakly coupled new neutral gauge boson forms a narrow resonance that is
hard to discover directly in e+e- collisions. However, if the gauge boson mass
is below the center-of-mass energy, it can be produced through processes where
the effective energy is reduced due to initial-state radiation and
beamstrahlung. It is shown that at a high-luminosity linear collider, such a
gauge boson can be searched for with very high sensitivity, leading to a
substantial improvement compared to existing limits from the Tevatron and also
extending beyond the expected reach of the LHC in most models. If a new vector
boson is discovered either at the Tevatron Run II, the LHC or the linear
collider, its properties can be determined at the linear collider with high
precision, thus helping to reveal origin of the new boson.Comment: 21 p
The compound Poisson limit ruling periodic extreme behaviour of non-uniformly hyperbolic dynamics
We prove that the distributional limit of the normalised number of returns to
small neighbourhoods of periodic points of non-uniformly hyperbolic dynamical
systems is compound Poisson. The returns to small balls around a fixed point in
the phase space correspond to the occurrence of rare events, or exceedances of
high thresholds, so that there is a connection between the laws of Return Times
Statistics and Extreme Value Laws. The fact that the fixed point in the phase
space is a repelling periodic point implies that there is a tendency for the
exceedances to appear in clusters whose average sizes is given by the Extremal
Index, which depends on the expansion of the system at the periodic point.
We recall that for generic points, the exceedances, in the limit, are
singular and occur at Poisson times. However, around periodic points, the
picture is different: the respective point processes of exceedances converge to
a compound Poisson process, so instead of single exceedances, we have entire
clusters of exceedances occurring at Poisson times with a geometric
distribution ruling its multiplicity.
The systems to which our results apply include: general piecewise expanding
maps of the interval (Rychlik maps), maps with indifferent fixed points
(Manneville-Pomeau maps) and Benedicks-Carleson quadratic maps.Comment: To appear in Communications in Mathematical Physic
Outflows in the Narrow Line Region of Bright Seyfert Galaxies - I: GMOS-IFU Data
We present two-dimensional maps of emission-line fluxes and kinematics, as
well as of the stellar kinematics of the central few kpc of five bright nearby
Seyfert galaxies -- Mrk\,6, Mrk\,79, Mrk\,348, Mrk\,607 and Mrk\,1058 --
obtained from observations with the Gemini Multi-Object Spectrograph (GMOS)
Integral Field Unit (IFU) on the Gemini North Telescope. The data cover the
inner 3\farcs55\farcs0 -- corresponding to physical scales in the range
0.60.9 to 1.52.2\,kpc -- at a spatial resolution ranging
from 110 to 280 pc with a spectral coverage of 4300 -- 7100\,\AA\ and velocity
resolution of 90\,km\,s. The gas excitation is Seyfert like
everywhere but show excitation, but show excitation gradients that are
correlated with the gas kinematics, reddening and/or the gas density. The gas
kinematics show in all cases two components: a rotation one similar to that
observed in the stellar velocity field, and an outflow component. In the case
of Mrk607, the gas is counter-rotating relative to the stars. Enhanced gas
velocity dispersion is observed in association to the outflows according to two
patterns: at the locations of the highest outflow velocities along the
ionization axis or perpendicularly to it in a strip centered at the nucleus
that we attribute to an equatorial outflow. Bipolar outflows are observed in
Mrk\,348 and Mrk\,79, while in Mrk\,1058 only the blueshifted part is clearly
observed, while in the cases of Mrk\,6 and Mrk\,607 the geometry of the outflow
needs further constraints from modeling to be presented in a forthcoming study,
where the mass flow rate and powers will also be obtained.Comment: 20 pages, accepted by MNRA
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