38 research outputs found
Light Higgs Boson from a Pole Attractor
We propose a new way of explaining the observed Higgs mass, within the
cosmological relaxation framework. The key feature distinguishing it from other
scanning scenarios is that the scanning field has a non-canonical kinetic term,
whose role is to terminate the scan around the desired Higgs mass value. We
propose a concrete realisation of this idea with two new singlet fields, one
that scans the Higgs mass, and another that limits the time window in which the
scan is possible. Within the provided time period, the scanning field does not
significantly evolve after the Higgs field gets close to the Standard Model
value, due to particle production friction.Comment: version published in PR
The Holographic Superconductor Vortex
A gravity dual of a superconductor at finite temperature has been recently
proposed. We present the vortex configuration of this model and study its
properties. In particular, we calculate the free energy as a function of an
external magnetic field, the magnetization and the superconducting density. We
also find the two critical magnetic fields that define the region in which the
vortex configurations are energetically favorable.Comment: Few changes. Version to appear in Phys. Rev. Let
SUSY Faces its Higgs Couplings
In supersymmetric models, a correlation exists between the structure of the
Higgs sector quartic potential and the coupling of the lightest CP-even Higgs
to fermions and gauge bosons. We exploit this connection to relate the observed
value of the Higgs mass ~ 125 GeV to the magnitude of its couplings. We analyze
different scenarios ranging from the MSSM with heavy stops to more natural
models with additional non-decoupling D-term/F-term contributions. A comparison
with the most recent LHC data, allows to extract bounds on the heavy Higgs
boson masses, competitive with bounds from direct searches.Comment: 14 pages plus appendix; 9 figure
Correlating Non-Resonant Di-Electron Searches at the LHC to the Cabibbo-Angle Anomaly and Lepton Flavour Universality Violation
In addition to the existing strong indications for lepton flavour university
violation (LFUV) in low energy precision experiments, CMS recently released an
analysis of non-resonant di-lepton pairs which could constitute the first sign
of LFUV in high-energy LHC searches. In this article we show that the Cabibbo
angle anomaly, an (apparent) violation of first row and column CKM unitarity
with significance, and the CMS result can be correlated and
commonly explained in a model independent way by the operator .
This is possible without violating the bounds from the non-resonant di-lepton
search of ATLAS (which interestingly also observed slightly more events than
expected in the electron channel) nor from . We find a combined preference for the new physics hypothesis of
and predict (95\%~CL) which can be tested
in the near future with the forthcoming results of the PEN experiment.Comment: 6 pages, 2 figure
Higgs Couplings in Composite Models
We study Higgs couplings in the composite Higgs model based on the coset
SO(5)/SO(4). We show that the couplings to gluons and photons are insensitive
to the elementary-composite mixings and thus not affected by light fermionic
resonances. Moreover, at leading order in the mixings the Higgs couplings to
tops and gluons, when normalized to the Standard Model (SM), are equal. These
properties are shown to be direct consequences of the Goldstone symmetry and of
the assumption of partial compositeness. In particular, they are independent of
the details of the elementary-composite couplings and, under the further
assumption of CP invariance, they are also insensitive to derivative
interactions of the Higgs with the composite resonances. We support our
conclusions with an explicit construction where the SM fermions are embedded in
the 14 dimensional representation of SO(5).Comment: 13 pages, 3 figures, 2 tables; v2: small improvements in the
discussion, results unchanged; typos corrected; one reference added. Matches
version submitted to PR
災害時における男女共同参画センターの情報機能の役割に関する一考察 : 阪神・淡路大震災から熊本地震までの連携・協力を中心に
We propose to replace the exact amplitudes used in MC event generators for
trained Machine Learning regressors, with the aim of speeding up the evaluation
of {\it slow} amplitudes. As a proof of concept, we study the process whose LO amplitude is loop induced. We show that gradient boosting machines
like can predict the fully differential distributions with
errors below , and with prediction times faster
than the evaluation of the exact function. This is achieved with training times
minutes and regressors of size ~Mb. These results suggest
a possible new avenue to speed up MC event generators.Comment: 5+2 pages, 5 figures, and 2 tables; fixed minor typos, merged two
figures, and updated acknowledgements of suppor
Global Electroweak Fit and Vector-Like Leptons in Light of the Cabibbo Angle Anomaly
The "Cabibbo Angle Anomaly" (CAA) originates from the disagreement between
the CKM elements and extracted from superallowed beta and
kaon decays, respectively, once compared via CKM unitarity. It points towards
new physics with a significance of up to , depending on the
theoretical input used, and can be explained through modified couplings to
leptons. In this context, vector-like leptons (VLLs) are prime candidates for a
corresponding UV completion since they can affect couplings at
tree-level, such that this modification can have the dominant phenomenological
impact. In order to consistently asses the agreement with the data, a global
fit is necessary which we perform for gauge-invariant dimension-6 operators and
all patterns obtained for the six possible representations (under the SM gauge
group) of VLLs. We find that even in the lepton flavour universal case,
including the measurements of the CKM elements and into the
electroweak fit has a relevant impact, shifting the best fit point
significantly. Concerning the VLLs we discuss the bounds from charged lepton
flavour violating processes and observe that a single representation cannot
describe experimental data significantly better than the SM hypothesis.
However, allowing for several representations of VLLs at the same time, we find
that the simple scenario in which couples to electrons via the Higgs and
couples to muons not only explains the CAA but also improves the
rest of the electroweak fit in such a way that its best fit point is preferred
by more than with respect to the SM.Comment: Version accepted for publication in JHEP, 34 pages, 9 figures, 7
tables, typos correcte
Hadronic vacuum polarization: versus global electroweak fits
Hadronic vacuum polarization (HVP) is not only a critical part of the
Standard Model (SM) prediction for the anomalous magnetic moment of the muon
, but also a crucial ingredient for global fits to electroweak (EW)
precision observables due to its contribution to the running of the
fine-structure constant encoded in . We find
that with modern EW precision data, including the measurement of the Higgs
mass, the global fit alone provides a competitive, independent determination of
. This
value actually lies below the range derived from
cross-section data, and thus goes into the opposite direction as would be
required if a change in HVP were to bring the SM prediction for
into agreement with the Brookhaven measurement. Depending on the energy where
the bulk of the changes in the cross section occurs, reconciling experiment and
SM prediction for by adjusting HVP would thus not necessarily
weaken the case for physics beyond the SM (BSM), but to some extent shift it
from to the EW fit. We briefly explore some options of BSM
scenarios that could conceivably explain the ensuing tension.Comment: 7 pages, 2 figures; journal versio
Flux Periodicities and Quantum Hair on Holographic Superconductors
Superconductors in a cylindrical geometry respond periodically to a
cylinder-threading magnetic flux, with the period changing from hc/2e to hc/e
depending on whether the Aharonov-Bohm effects are suppressed or not. We show
that Holographic Superconductors present a similar phenomenon, and that the
different periodicities follow from classical no-hair theorems. We also give
the Ginzburg-Landau description of the period-doubling phenomenon.Comment: 4 pages, 3 figures; article published in Physical Review Letter