1,130 research outputs found
Gauge-invariant implications of the LHCb measurements on Lepton-Flavour Non-Universality
We study the implications of the recent measurements of and
by the LHCb collaboration. We do that by adopting a model-independent approach
based on the Standard Model Effective Field Theory (SMEFT), in which the
dominant new physics effects are encoded in the coefficients of dimension-six
operators respecting the full Standard Model (SM) gauge symmetry. After
providing simplified expressions for and , we determine the
implications of the recent LHCb results for these observables on the
coefficients of the SMEFT operators at low and high energies. We also take into
account all data, which combined lead to effective New
Physics (NP) scenarios with SM pulls in excess of 5~. Thus the
operators discussed in this paper would be the first dimension-six terms in the
SM Lagrangian to be detected experimentally. Indirect constraints on these
operators are also discussed. The results of this paper transcend the
singularity of the present situation, and set a standard for future analyses in
transitions when the NP is assumed to lie above the electroweak scale.Comment: 10 pages, 2 figures, 3 tables. v2: references added, typos corrected,
improved discussion in Sec. V, corrected coefficient of C7 in formula for
RKstar in the low-bin, new figure with global fit in terms of SMEFT
coefficients. Conclusions unchanged. v3: minor addition, shorter version to
be published in PR
Effective Aligned 2HDM with a DFSZ-like invisible axion
We discuss the possibility of having a non-minimal scalar sector at the weak
scale within the framework of invisible axion models. To frame our discussion
we consider an extension of the Dine-Fischler-Srednicki-Zhitnitsky invisible
axion model with two additional Higgs doublets blind under the Peccei-Quinn
symmetry. Due to mixing effects among the scalar fields, it is possible to
obtain a rich scalar sector at the weak scale in certain decoupling limits of
the theory. In particular, this framework provides an ultraviolet completion of
the so-called aligned two-Higgs-doublet model and solves the strong CP problem.
The axion properties and the smallness of active neutrino masses are also
discussed.Comment: 8 pages, 1 figure. Discussion improved, references added. Matching
the journal versio
Integrating out heavy particles with functional methods: a simplified framework
We present a systematic procedure to obtain the one-loop low-energy effective
Lagrangian resulting from integrating out the heavy fields of a given
ultraviolet theory. We show that the matching coefficients are determined
entirely by the hard region of the functional determinant involving the heavy
fields. This represents an important simplification with respect the
conventional matching approach, where the full and effective theory
contributions have to be computed separately and a cancellation of the infrared
divergent parts has to take place. We illustrate the method with a descriptive
toy model and with an extension of the Standard Model with a heavy real scalar
triplet. A comparison with other schemes that have been put forward recently is
also provided.Comment: 24 pages. Uses feynMF packag
Phenomenology of an model with lepton-flavour non-universality
We investigate a gauge extension of the Standard Model in light of the
observed hints of lepton universality violation in and decays at BaBar, Belle and LHCb. The model consists of an
extended gauge group which breaks spontaneously around the TeV scale to the
electroweak gauge group. Fermion mixing effects with vector-like fermions give
rise to potentially large new physics contributions in flavour transitions
mediated by and bosons. This model can ease tensions
in -physics data while satisfying stringent bounds from flavour physics, tau
decays, and electroweak precision data. Possible ways to test the proposed new
physics scenario with upcoming experimental measurements are discussed. Among
other predictions, the lepton flavour violating ratios , with , are found to be reduced with respect to the Standard Model expectation
.Comment: 46 pages, 11 figures. v2: version published in JHE
Non-abelian gauge extensions for B-decay anomalies
We study the generic features of minimal gauge extensions of the Standard
Model in view of recent hints of lepton-flavor non-universality in
semi-leptonic and decays. We
classify the possible models according to the symmetry-breaking pattern and the
source of flavor non-universality. We find that in viable models the
factor is embedded non-trivially in the extended gauge
group, and that gauge couplings should be universal, hinting to the presence of
new degrees of freedom sourcing non-universality. Finally, we provide an
explicit model that can explain the -decay anomalies in a coherent way and
confront it with the relevant phenomenological constraints.Comment: 8 pages, 2 figures; discussion improved, a figure and references
added; conclusions unchange
Lepton Flavor Non-Universality in B decays from Dynamical Yukawas
The basic features of quark and lepton mass matrices can be successfully
explained by natural minima of a generic potential with dynamical Yukawa fields
invariant under the flavor symmetry.
If this symmetry is gauged, in order to avoid potentially dangerous Goldstone
bosons, and small perturbations are added to exactly fit the observed pattern
of fermion masses, the spectrum of massive flavor gauge bosons can naturally
explain the hints for new physics in transitions,
including . In particular, the desired pattern of the Standard Model
Yukawa couplings is compatible with a gauged in the quark
sector, and in the lepton sector spontaneously
broken around the TeV scale. In order to explain the aforementioned
experimental hints, the corresponding neutral gauge bosons are required to mix,
yielding to potentially observable signals in dimuon resonance searches at the
LHC.Comment: 11 pages, 9 figures. v2: version published in Phys.Lett.
A three-site gauge model for flavor hierarchies and flavor anomalies
We present a three-site Pati-Salam gauge model able to explain the Standard
Model flavor hierarchies while, at the same time, accommodating the recent
experimental hints of lepton-flavor non-universality in decays. The model
is consistent with low- and high-energy bounds, and predicts a rich spectrum of
new states at TeV scale that could be probed in the near future by the
high- experiments at the LHC.Comment: 8 pages, 2 figures. v2: Added section II.B, matching the PLB versio
Surface Ornamentation Techniques and Spatial Distortion
[EN] Several different types of surface-related ornamentation that are capable of distorting the perception of space have been developed and used since ancient times. Some examples of these are di sotto in su, quadratura, trompe l'oeil and foreshortening. These techniques throw into question the limits of space and architecture and our understanding thereof. However, until now, there has been no clear classification or designation of these distortive techniques. Therefore, this article focuses on the identification and classification of three different ornamental techniques applied to surfaces that can distort the perception of space and looks to the work of various contemporary artists to exemplify the proposed taxonomy.Open Access funding enabled and organized by ProjektDEAL.Martin, J.; Martin Fuentes, DV. (2022). Surface Ornamentation Techniques and Spatial Distortion. Nexus Network Journal (Online). 24(3):529-544. https://doi.org/10.1007/s00004-022-00615-x52954424
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