A
bstract
A vector leptoquark at the TeV scale, mostly coupled to the fermions of the third generation, is the preferred option to explain the hints of lepton flavor universality violation in the ...decays of
B
-mesons. It seems interesting to assume that this leptoquark belongs to the same beyond the Standard Model sector that solves the hierarchy prob- lem, since the third generation of fermions play the leading role in the instability of the Higgs potential. We present a composite Grand Unified Theory with resonances at the TeV that contains the required vector leptoquark and develops the Higgs as a pseudo Nambu-Goldstone boson. We show that anarchic partial compositeness of the Standard Model fermions can accommodate the couplings of Left-handed currents required by the
B
-anomalies, predicting very small couplings to the Right-handed currents without any additional hypothesis. By making use of an effective theory description of the strong dy- namics, in terms of weakly coupled resonances, we are able to compute the corrections to
B
-physics, as well as the one-loop potential for the pseudo Nambu-Goldstone bosons. The theory has a rich phenomenology and a candidate for dark matter.
Based on the AdS/CFT correspondence we study the breaking of the chiral symmetry in QCD using a simple five-dimensional model. The model gives definite predictions for the spectrum of vector mesons, ...their decay constants and interactions as a function of one parameter related to the quark condensate. We calculate the coefficients
L
i
of the low-energy QCD chiral Lagrangian, as well as other physical quantities for the pions. All the predictions are shown to be in good agreement with the experimental data. We also show that they are robust under modifications of the 5D metric in the IR, and that some of them arise as a consequence of the higher-dimensional gauge symmetry. For example, at the tree-level, we find
M
ρ
≃
3
g
ρ
π
π
F
π
,
F
ρ
≃
3
F
π
and
BR
(
a
1
→
π
γ
)
=
0
.
A
bstract
We propose a composite grand unified theory to study the anomalies in the semileptonic
B
decays. We show a simple group containing the custodial and Standard Model gauge symmetries, that ...can deliver a set of composite pseudo Nambu-Goldstone bosons: the Higgs, a colorless SU(2)
L
-fourplet and three leptoquarks: a triplet and two doublets. We give a description in terms of an effective theory of resonances. By assuming anarchic partial compositeness of the Standard Model fermions, we find representations for the composite fermions that allow to obtain the Higgs Yukawa couplings, as well as leptoquark interactions explaining the deviations in
R
K
*
μ
e
. We calculate the one-loop potential, we show that it can trigger electroweak symmetry breaking and we find a region of the parameter space that can reproduce the Standard Model spectrum. The model predicts leptoquark masses of order 0.4–1.3 TeV, corrections to some electroweak observables, with
Z
b
L
b
¯
L
saturating the current bounds, and a very reach phenomenology at LHC. We also study the possibility of explaining
R
D
*
τ
ℓ
.
A
bstract
Composite Higgs models with anarchic partial compositeness require a scale of new physics
O
10
−
100
TeV, with the bounds being dominated by the dipole moments and
ϵ
K
. The presence of ...anarchic bilinear interactions can change this picture. We show a solution to the SM flavor puzzle where the electron and the Right-handed quarks of the first generation have negligible linear interactions, and the bilinear interactions account for most of their masses, whereas the other chiral fermions follow a similar pattern to anarchic partial compositeness. We compute the bounds from flavor and CP violation and show that neutron and electron dipole moments, as well as
ϵ
K
and
μ
→
e
γ, are compatible with a new physics scale below the TeV. Δ
F
= 2 operators involving Left-handed quarks and Δ
F
= 1 operators with
d
L
give the most stringent bounds in this scenario. Their Wilson coefficients have the same origin as in anarchic partial compositeness, requiring the masses of the new states to be larger than
O
6
−
7
TeV.
A
bstract
Since the discovery in 2012 of the Higgs boson at the LHC, as the last missing piece of the Standard Model of particle physics, any hint of new physics has been intensively searched for, ...with no confirmation to date. There are however slight deviations from the SM that are worth investigating. The CMS collaboration has reported, in a search for heavy resonances decaying in
t
t
¯
with a 13-TeV center-of-mass energy and a luminosity of 35.9 fb
−
1
, deviations from the SM predictions at the 3.5
σ
level locally (1.9
σ
after the look-elsewhere effect). In addition, in the ditau final state search performed by the ATLAS collaboration at
s
= 13 TeV and
L
= 139 fb
−
1
, deviations from the SM at the 2
σ
level have been also observed. Interestingly, both slight excesses are compatible with a new pseudoscalar boson with a mass around 400 GeV that couples at least to fermions of the third generation and gluons. Starting from a purely phenomenological perspective, we inspect the possibility that a 400-GeV pseudoscalar can account for these deviations and at the same time satisfy the constraints on the rest of the channels that it gives contributions to and that are analyzed by the ATLAS and CMS experiments. After obtaining the range of effective couplings compatible with all experimental measurements, we study the gauge invariant UV completions that can give rise to this type of pseudoscalar resonance, which can be accommodated in an SO(6)
/
SO(5) model with consistency at the 1
σ
level and in a SO(5) × U(1)
P
× U(1)
X
/SO(4) × U(1)
X
at the 2
σ
level, while exceedingly large quartic couplings would be necessary to account for it in a general two Higgs doublet model.
The minimal simple composite Higgs model Da Rold, Leandro; Rossia, Alejo N.
The journal of high energy physics,
12/2019, Letnik:
2019, Številka:
12
Journal Article
Recenzirano
Odprti dostop
A
bstract
Most of the analysis of composite Higgs have focussed on the Minimal Composite Higgs Model, based on the coset SO(5)
×
U(1)
X
/
SO(4)
×
U(1)
X
. We consider a model based on the coset of ...simple groups SO(7)
/
SO(6), with SO(4)
×
U(1)
X
embedded into SO(6). This extension of the minimal model leads to a new complex pNGB that has hypercharge and is a singlet of SU(2)
L
, with properties mostly determined by the pattern of symmetry breaking and a mass of order TeV. Composite electroweak unification also leads to new bosonic and fermion resonances with exotic charges, not present in the minimal model, the lightest of these resonances being stable. A new rich phenomenology is expected at LHC.
A
bstract
Measurements of single Higgs production and its decays are in good agreement with the Standard Model. There is still room for large modifications in double Higgs production at LHC, though ...these effects may be correlated with large corrections to other observables, in particular single Higgs production. In this work we address the issue of enhancing double Higgs production in the presence of scalar leptoquarks while satisfying all experimental constraints. We show at leading order that including more than one species of leptoquarks, large cubic interactions with the Higgs can lead to sizable enhancement of di-Higgs production cross section at LHC, while at the same time keeping other Higgs observables and precision measurements under control. For masses above 800 GeV these corrections are in general below 30%, whereas in a viable scenario in which one of the leptoquarks can be light, specifically in the mass range 400
−
600 GeV, we show that it is possible to roughly double the SM cross section for di-Higgs production, implying that possible first hints of it may be probed at the high luminosity LHC at
L
∼ 2 ab
−
1
.
Embodied and situated view of cognition is a transdisciplinary framework which stresses the importance of real time and dynamical interaction of an agent with the surrounding environment. This ...article presents a series of evolutionary robotics experiments that operationalize such concept, training miniature two-wheeled mobile robots to autonomously solve a temporal task. In order to provide a numerical description of the robots’ behavior, chaotic measures are estimated on the attractor reconstructed from the recorded positions of the agent. Chaos theory provides a rigorous mathematical framework consistent with an antireductionist approach, useful for understanding embodied and situated systems while avoiding a decomposition of the integrated system brain–body–environment. Time series are analyzed in detail using nonlinear mathematical tools in order to verify the presence of low-dimensional deterministic dynamical systems, a fundamental prerequisite for chaos theory. In particular, the recorded time series are evaluated with nonlinear prediction error to unveil deterministic dynamics, cross-prediction error to determine the stationarity of the signal, and surrogate data testing to verify the existence of nonlinear components in the underlying system. Estimators for quantifying level of chaos and fractal dimension are applied to suitable datasets. Results show that robots governed by a chaotic dynamic are more efficient at adapting to environments never experience during evolution, demonstrating robustness towards novel and unpredictable situations. Furthermore, chaotic measures, in particular fractal dimension, are correlated with the performance if robots exhibit a similar behavioral strategy.
•Proposing chaos theory for the analysis of embodied and situated systems.•Operationalizing the definition of chaos with nonlinear time series analysis.•Robots that exhibit a chaotic behaviour are resilient towards unknown environments.•Fractal dimension is correlated with the performance of the robots.
Objective
Electroencephalographic (EEG) microstate abnormalities have been documented in different neurological disorders. We aimed to assess whether EEG microstates are altered also in patients with ...temporal epilepsy (TLE) and whether they show different activations in patients with unilateral TLE (UTLE) and bilateral TLE (BTLE).
Methods
Nineteen patients with UTLE, 12 with BTLE, and 15 healthy controls were enrolled. Resting state high‐density electroencephalography (128 channels) was recorded for 15 min with closed eyes. We obtained a set of stable scalp maps representing the EEG activity, named microstates, from which we acquired the following variables: global explained variance (GEV), mean duration (MD), time coverage (TC), and frequency of occurrence (FO). Two‐way repeated measures analysis of variance was used to compare groups, and Spearman correlation was performed to study the maps in association with the clinical and neuropsychological data.
Results
Patients with BTLE and UTLE showed differences in most of the parameters (GEV, MD, TC, FO) of the four microstate maps (A–D) compared to controls. Patients with BTLE showed a significant increase in all parameters for the microstates in Map‐A and a decrease in Map‐D compared to UTLE and controls. We observed a correlation between Map‐A, disease duration, and spatial short‐term memory, whereas microstate Map‐D was correlated with the global intelligence score and short‐term memory performance.
Significance
A global alteration of the neural dynamics was observed in patients with TLE compared to controls. A different pattern of EEG microstate abnormalities was identified in BTLE compared to UTLE, which might represent a distinctive biomarker.
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