755 research outputs found
Extra Quarks and Bileptons in BSM Physics in a Model
We describe some salient features of the (Frampton-Pisano-Pleitez)
bilepton model, in which the constraints of anomaly cancelation require the
number of generations to be three. In a class of six models, four of which
characterised by a parameter describing the embedding of the
hypercharge in the symmetry, a specific choice for allows
bileptons in the spectrum, i.e. vectors and scalars of lepton numbers .
At the same time the model allows exotic quarks, with the third quark
generation treated asymmetrically respect to the other two. Bileptons generate
specific signatures in the form of multilepton final states in Drell-Yan like
processes, with and without associated jets, which can be searched for at the
LHC.Comment: 7 pages, 2 Figures. Proceedings of the Workshop QCD@work 2018, 25-28
June 2018, Matera, Ital
A Simple Panel-CADF Test for Unit Roots
In this paper we propose a simple extension to the panel case of the covariate-augmented Dickey Fuller (CADF) test for unit roots developed in Hansen (1995). The extension we propose is based on a p-values combination approach that takes into account cross-section dependence. We show that the test is easy to compute, has good size properties and gives power gains with respect to other popular panel approaches. A procedure to compute the asymptotic p-values of Hansen’s CADF test is also a side-contribution of the paper. We also complement Hansen (1995) and Caporale and Pittis (1999) with some new theoretical results. Two empirical applications are carried out for illustration purposes on international data to test the PPP hypothesis and the presence of a unit root in international industrial production indices.Unit root, panel data, approximate p-values, Monte Carlo
Stochastic convergence among European economies
The aim of this paper is to test the stochastic convergence in real per capita GDP for 15 European countries using non-stationary panel data approaches over the period 1950-2003. Cross-sectional dependence is assumed due to the existence of strong linkages among European economies. However, tests derived under the assumption of cross-sectional independence are also carried out for completeness and comparison. We also split the whole sample into two sub-periods (1950-1976, 1977-2003) in order to take into account the effects of the first oil crisis (1973-1974) and to evaluate the robustness of the statistical analysis. Our results offer little support to the stochastic convergence hypothesis for the whole period, while suggest the presence of convergence in the first sub-period.Convergence
A Simple Panel-CADF Test for Unit Roots
In this paper we propose a simple extension to the panel case of the covariate- augmented Dickey Fuller (CADF) test for unit roots developed in Hansen (1995). The extension we propose is based on a p values combination approach that takes into account cross-section dependence. We show that the test is easy to compute, has good size properties and gives power gains with respect to other popular panel approaches. A procedure to compute the asymptotic p values of Hansen's CADF test is also a side-contribution of the paper. We also complement Hansen (1995) and Caporale and Pittis (1999) with some new theoretical results. Two empirical applications are carried out for illustration purposes on international data to test the PPP hypothesis and the presence of a unit root in international industrial production indices.Unit Root, Panel data, Approximate p values, Monte Carlo
Perspectives on a Supersymmetric Extension of the Standard Model with a Higgs Triplet and a Singlet at the LHC
We investigate a supersymmetric extension of the Minimal Supersymmetric
Standard Model (MSSM), called the TNMSSM, containing a Higgs triplet
of hypercharge and a singlet superfields in the
corresponding superpotential. The model can be viewed, equivalently, as an
extension of the NMSSM with the addition of a interaction and
of an extra coupling of the triplet to the two Higgs doublets of the NMSSM. In
this scenario the Higgs particle spectrum at tree-level gets additional mass
contributions from the triplet and singlet scalar components respect to the
MSSM, which are particularly enhanced at low . We calculate the
one-loop Higgs masses for the neutral physical Higgs bosons by a
Coleman-Weinberg effective potential approach. In particular, we investigate
separately the impact of the radiative corrections due to the electroweak,
gauge-gaugino-higgsino, fermion-sfermion and Higgs self-interactions to the
Higgs masses. Due to the larger number of scalars and of triplet and singlet
couplings, the Higgs corrections can be larger than the strong corrections.
This reduces the amount of fine-tuning required to fit the recent Higgs data.
Using the expressions of the beta-functions of the model, we show that the
large triplet singlet coupling remains perturbative up to GeV.
The model is also characterized by a light pseudoscalar in the spectrum, which
is a linear combination of the triplet, doublet and singlet CP-odd components.
We discuss the production and decay signatures of the Higgs bosons in this
model, including scenarios with hidden Higgses, which could be investigated at
the LHC in the current run.Comment: 39 pages, 37 figures, comments added for the published versio
Higgs bosons: discovered and hidden, in extended Supersymmetric Standard Models at the LHC
We investigate an extension of the Minimal Supersymmetric Standard Model
(MSSM) containing a Higgs triplet of zero hypercharge and a gauge
singlet. We focus on a scenario of this model which allows a light pseudoscalar
and/or a scalar below GeV in the spectrum, consistent with the most
recent data from the LHC and the earlier data from the LEP experiments. We
analyze the exotic decay of the discovered Higgs into two light
(hidden) Higgs bosons present in the extension. The latter are allowed by the
uncertainties in the Higgs decay , and
. We have searched for such light Higgs bosons in the
, , and final states at the LHC
with 13 and 14 TeV. A region of such parameter space can be explored with an
integrated luminosity of 25 fb at the LHC.Comment: 12 pages, 10 figures, CORFUR2015. arXiv admin note: text overlap with
arXiv:1506.0363
A Characterization of the Dickey-Fuller Distribution, With Some Extensions to the Multivariate Case
This paper provides a theoretical functional representation of the density function related to the Dickey- Fuller random variable. The approach is extended to cover the multivariate case in two special frameworks: the independence and the perfect correlation of the series.Dickey-Fuller distribution, unit root
FDR Control in the Presence of an Unknown Correlation Structure
The false discovery rate (FDR, Benjamini and Hochberg 1995) is a powerful approach to multiple testing. However, the original approach developed by Benjamini and Hochberg (1995) applies only to independent tests. Yekutieli (2008) showed that a modification of the Benjamini-Hochberg (BH) approach can be used in the presence of dependent tests and labelled his procedure as separate subsets BH (ssBH). However, Yekutieli (2008) left the practical specification of the subsets of p values largely unresolved. In this paper we propose a modification of the ssBH procedure based on a selection of the subsets that guarantees that the dependence properties needed to control the FDR are satisfied. We label this new procedure as the separate pairs BH (spBH). An extensive Monte Carlo analysis is presented that compares the properties of the BH and spBH procedures.Multiple testing, False discovery rate, Copulas
Bilepton Signatures at the LHC
We discuss the main signatures of the Bilepton Model at the Large Hadron
Collider, focusing on its gauge boson sector. The model is characterised by
five additional gauge bosons, four charged and one neutral, beyond those of the
Standard Model, plus three exotic quarks. The latter turn into ordinary quarks
with the emission of bilepton doublets and of
lepton number and respectively, with the doubly-charged bileptons
decaying into same-sign lepton pairs. We perform a phenomenological analysis
investigating processes with two doubly-charged bileptons and two jets at the
LHC and find that, setting suitable cuts on pseudorapidities and transverse
momenta of final-states jets and leptons, the model yields a visible signal and
the main Standard Model backgrounds can be suppressed. Compared to previous
studies, our investigation is based on a full Monte Carlo implementation of the
model and accounts for parton showers, hadronization and an actual
jet-clustering algorithm for both signal and Standard Model background, thus
providing an optimal framework for an actual experimental search.Comment: 13 pages, 5 figures. Extended final version, to appear on Phys. Lett.
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