arXiv subjects

Giovanni Marco Pruna

Publications and source records attributed to Giovanni Marco Pruna.

33 records · Page 2Linked to original sources

arXiv2013

Composite Higgs: searches for new physics at future $e^+e^-$ colliders

In this proceeding, we extend a previous analysis concerning the prospects of a future electron-positron collider in testing the 4-Dimensional Composite Higgs Model. In particular, we introduce two motivated benchmarks and study them in Higgs-Strahlung, for three possible energy stages and different luminosity options of such a machine and confront our results to the expected experimental accuracies in the various accessible Higgs decay channels.

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arXiv2013

Exploring Drell-Yan signals from the 4D Composite Higgs Model at the LHC

We study the phenomenology of Drell-Yan processes at the Large Hadron Collider for the case of both the neutral and charged current channels within a recently proposed 4-Dimensional formulation of the Minimal Composite Higgs Model. We estimate the integrated and differential event rates at the CERN machine, assuming 14 TeV and data samples of ${\cal O}(100 {\rm{fb}}^{-1})$, as at lower energy and/or luminosity event rates are prohibitively small. We pay particular attention to the presence of multiple resonances in either channel, by showing that in certain region of parameter space some of these can be distinguishable and experimentally accessible in the invariant and/or transverse mass distribution, sampled in either the cross section, the forward-backward asymmetry or both. At the same time, we assess the indirect impact onto the line-shape of the emerging gauge boson resonances, both neutral and charged, of additional heavy fermionic states present in the spectrum of the model. Finally, we show how to exploit in the kinematic selection the fact that the extra neutral and charged gauge boson resonances in composite Higgs models are correlated in mass. Such results rely on a parton level study including a statystical error analysis.

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arXiv2013

The CP-violating type-II 2HDM and Charged Higgs boson benchmarks

We review and update the interpretation of the 125 GeV scalar as the lightest Higgs boson of the Two-Higgs-Doublet Model, allowing for CP violation in the potential. The detection of a charged Higgs boson would exclude the Standard Model. Proposed benchmarks for charged-Higgs searches in the channel pp\to H^+W^-X\to W^+W^-H_1X are reviewed and updated.

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arXiv2013

Charged Higgs boson benchmarks in the CP-violating type-II 2HDM

We discuss prospects for discovering a charged Higgs boson in the CP-violating type-II two-Higgs-doublet Model. In the light of recent LHC data, we focus on the parameter space that survives experimental as well as the theoretical constraints on the model. Once the phenomenological scenario is set, we analyse the scope for the LHC to discover a charged Higgs in association with the lightest neutral Higgs and a charged vector boson.

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arXiv2012

Leptonic final states from di-boson production at the LHC in the 4-Dimensional Composite Higgs Model

We study di-boson production via both neutral and charged current at the Large Hadron Collider, i.e. subprocesses $q\bar q\to e^+ν_e μ^-\barν_μ$ + ${\rm{c.c.}}$ and $q\bar q'\to l^+ν_l l^{'+}l^{'-}$ + ${\rm{c.c.}}$, respectively, where $q,q'$ are quarks and $l,l'=e,μ$, in all possible combinations, in the context of the 4-Dimensional Composite Higgs Model. These modes enable the production in the intermediate steps of several additional -- with respect to the Standard Model -- neutral and charged gauge bosons belonging to the spectrum of this scenario, all of which in resonant topologies. We not only find these channels to be accessible over the background but also show that, after a dedicated cut-based analysis, kinematic reconstruction of most such resonances is always possible. However, since the Electro-Weak precision data generally disfavor neutral and charged gauge boson masses below the TeV range and also their large couplings to light-fermions, these modes turn out to be relevant only for the 14 TeV option with high integrated luminosity.

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arXiv2012

The pure $B-L$ model and future linear colliders: the Higgs sector

We summarise the phenomenology of the Higgs sector of the minimal $B-L$ extension of the Standard Model at an $e^+e^-$ Linear Collider. Within such a scenario, we show that (in comparison with the Large Hadron Collider) several novel production and decay channels involving the two physical Higgs states could experimentally be accessed at such a machine. In particular, we present the scope of the $Z'$ strahlung process for single and double Higgs production, the only suitable mechanism for accessing an almost decoupled heavy scalar state.

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arXiv2012

Constraining the $g'_1$ coupling in the minimal $B-L$ Model

We have combined the perturbative unitarity and the renormalisation group equations arguments in order to find a dynamical way to constrain the $g'_1$ coupling of the minimal $B-L$ extension of the Standard Model. We have analysed the role of the $g'_1$ coupling evolution in the perturbative stability of the two-to-two body scattering amplitudes of the vector boson and scalar sectors of the model and we have shown that the perturbative unitarity imposes an upper bound on the $B-L$ gauge coupling. We have made a comparison between this criterion and the triviality arguments, showing that our procedure substantially refines the triviality bounds.

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arXiv2011

Theoretical constraints on the couplings of non-exotic minimal $Z'$ bosons

We have combined perturbative unitarity and renormalisation group equation arguments in order to find a dynamical way to constrain the space of the gauge couplings ($g'_1$, $\widetilde{g}$) of the so-called "Minimal $Z'$ Models". We have analysed the role of the gauge couplings evolution in the perturbative stability of the two-to-two body scattering amplitudes of the vector and scalar sectors of these models and we have shown that perturbative unitarity imposes an upper bound that is generally stronger than the triviality constraint. We have also demonstrated how this method quantitatively refines the usual triviality bound in the case of benchmark scenarios such as the $U(1)_χ$, the $U(1)_R$ or the "pure" $U(1)_{B-L}$ extension of the Standard Model. Finally, a description of the underlying model structure in Feynman gauge is provided.

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arXiv2011

The Higgs sector of the minimal B-L model at future Linear Colliders

We investigate the phenomenology of the Higgs sector of the minimal $B-L$ extension of the Standard Model at a future $e^+e^-$ Linear Collider. We consider the discovery potential of both a sub-TeV and a multi-TeV machine. We show that, within such a theoretical scenario, several novel production and decay channels involving the two physical Higgs states, precluded at the LHC, could experimentally be accessed at such machines. Amongst these, several Higgs signatures have very distinctive features with respect to those of other models with enlarged Higgs sector, as they involve interactions of Higgs bosons between themselves, with $Z'$ bosons as well as with heavy neutrinos. In particular, we present the scope of the $Z'$ strahlung process for single and double Higgs production, the only suitable mechanism enable one to access an almost decoupled heavy scalar state (therefore outside the LHC range).

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arXiv2011

Phenomenology of the minimal $B-L$ Model: the Higgs sector at the Large Hadron Collider and future Linear Colliders

This Thesis is devoted to the study of the phenomenology of the Higgs sector of the minimal $B-L$ extension of the Standard Model at present and future colliders. Firstly, the motivations that call for the minimal $B-L$ extension are summarised. In addition, the model is analysed in its salient parts. Moreover, a detailed review of the phenomenological allowed Higgs sector parameter space is given. Finally, a complete survey of the distinctive Higgs boson signatures of the model at both the Large Hadron Collider and the future linear colliders is presented.

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arXiv2011

$Z'$ discovery potential at the LHC in the minimal $B-L$ extension of the Standard Model

We present the Large Hadron Collider (LHC) discovery potential in the $Z'$ sector of a $U(1)_{B-L}$ enlarged Standard Model (that also includes three heavy Majorana neutrinos and an additional Higgs boson) for $\sqrt{s}=7$, 10 and 14 TeV centre-of-mass (CM) energies, considering both the $Z'_{B-L}\rightarrow e^+e^-$ and $Z'_{B-L}\rightarrow μ^+μ^-$ decay channels. The comparison of the (irreducible) backgrounds with the expected backgrounds for the D$Ø$ experiment at the Tevatron validates our simulation. We propose an alternative analysis that has the potential to improve the D$Ø$ sensitivity. Electrons provide a higher sensitivity to smaller couplings at small $Z'_{B-L}$ boson masses than do muons. The resolutions achievable may allow the $Z'_{B-L}$ boson width to be measured at smaller masses in the case of electrons in the final state. The run of the LHC at $\sqrt{s}=7$ TeV, assuming at most $\int \mathcal{L} \sim 1$ fb$^{-1}$, will be able to give similar results to those that will be available soon at the Tevatron in the lower mass region, and to extend them for a heavier $M_{Z'}$.

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arXiv2011

Phenomenology of the minimal $B-L$ extension of the Standard Model: the Higgs sector

We investigate the phenomenology of the Higgs sector of the minimal $B-L$ extension of the Standard Model. We present results for both the foreseen energy stages of the Large Hadron Collider ($\sqrt s=7$ and 14 TeV). We show that in such a scenario several novel production and decay channels involving the two physical Higgs states could be accessed at such a machine. Amongst these, several Higgs signatures have very distinctive features with respect to those of other models with enlarged Higgs sector, as they involve interactions of Higgs bosons between themselves, with $Z'$ bosons as well as with heavy neutrinos.

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arXiv2010

Z' physics with early LHC data

We discuss the prospects for setting limits on or discovering spin-1 $Z'$ bosons using early LHC data at 7 TeV. Our results are based on the narrow width approximation in which the leptonic Drell-Yan $Z'$ boson production cross-section only depends on the $Z'$ boson mass together with two parameters $c_u$ and $c_d$. We carefully discuss the experimental cuts that should be applied and tabulate the theoretical next-to-next-to-leading order corrections which must be included. Using these results the approach then provides a safe, convenient and unbiased way of comparing experiment to theoretical models which avoids any built-in model dependent assumptions. We apply the method to three classes of perturbative $Z'$ boson benchmark models: $E_6$ models, left-right symmetric models and sequential standard models. We generalise each class of model in terms of {mixing angles which continuously parametrize} linear combinations of pairs of generators and lead to distinctive orbits in the $c_u-c_d$ plane. We also apply this method to the strongly coupled four-site benchmark model in which two $Z'$ bosons are predicted. By comparing the experimental limits or discovery bands to the theoretical predictions on the $c_u$-$c_d$ plane, we show that the LHC at 7 TeV with integrated luminosity of 500 pb$^{-1}$ will greatly improve on current Tevatron mass limits for the benchmark models. If a $Z'$ is discovered our results show that measurement of the mass and cross-section will provide a powerful discriminator between the benchmark models using this approach.

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arXiv2010

A Renormalisation Group Equation Study of the Scalar Sector of the Minimal B-L Extension of the Standard Model

We present the complete set of Renormalisation Group Equations (RGEs) at one loop for the non-exotic minimal U(1) extension of the Standard Model (SM). It includes all models that are anomaly-free with the SM fermion content augmented by one Right-Handed (RH) neutrino per generation. We then pursue the numerical study of the pure B-L model, deriving the triviality and vacuum stability bounds on an enlarged scalar sector comprising one additional Higgs singlet field with respect to the SM.

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arXiv2009

Probing the $Z'$ sector of the minimal $B-L$ model at future Linear Colliders in the $e^+e^-\to μ^+μ^-$ process

We study the capabilities of future electron-positron Linear Colliders, with centre-of-mass energy at the TeV scale, in accessing the parameter space of a $Z'$ boson within the minimal $B-L$ model. In such a model, wherein the Standard Model gauge group is augmented by a broken $U(1)_{B-L}$ symmetry -- with $B(L)$ being the baryon(lepton) number -- the emerging $Z'$ mass is expected to be in the above energy range. We carry out a detailed comparison between the discovery regions mapped over a two-dimensional configuration space ($Z'$ mass and coupling) at the Large Hadron Collider and possible future Linear Colliders for the case of di-muon production. As known in the literature for other $Z'$ models, we confirm that leptonic machines, as compared to the CERN hadronic accelerator, display an additional potential in discovering a $B-L$ $Z'$ boson as well as in allowing one to study its properties at a level of precision well beyond that of any of the existing colliders.

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