Lorenzo Basso

Aix-Marseille University | AMU · Centre de Physique des Particules de Marseille (UMR 7346 CPPM)

The goal of this report is to summarize the current situation and discuss possible search strategies for charged scalars, in non-supersymmetric extensions of the Standard Model at the LHC. Such scalars appear in Multi-Higgs-Doublet models (MHDM), in particular in the popular Two-Higgs-Doublet model (2HDM), allowing for charged and more neutral Higg...

The hints for a new resonance at 750 GeV from ATLAS and CMS have triggered a significant amount of attention. Since the simplest extensions of the standard model cannot accommodate the observation, many alternatives have been considered to explain the excess. Here we focus on several proposed renormalisable weakly-coupled models and revisit results...

The hints for a new resonance at 750 GeV from ATLAS and CMS have triggered a significant amount of attention. Since the simplest extensions of the standard model cannot accommodate the observation, many alternatives have been considered to explain the excess. Here we focus on several proposed renormalisable weakly-coupled models and revisit results...

In recent years, the production of a SM particle with large missing transverse momentum, dubbed mono-X searches, have gained increasing attention. After the discovery of the Higgs boson in 2012, the run-II of the LHC will now scrutinise its properties, looking for BSM physics. In particular, one could search for mono-Higgs signals, that are typical...

I review the Higgs sector of the $U(1)_{B-L}$ extension of the minimal supersymmetric standard model (MSSM). I will show that the gauge kinetic mixing plays a crucial role in the Higgs phenomenology. Two light bosons are present, a MSSM-like one and a $B-L$-like one, that mix at one loop solely due to the gauge mixing. After briefly looking at cons...

We present an analysis of supersymmetric left-right symmetric models with Higgs fields lying in the adjoint representation of SU(2)R . These models feature a doubly-charged Higgs boson which gets its mass only at the loop level. We present, for the first time, a complete one-loop calculation of this mass and show that contributions that have been n...

We present the extension of two general algorithms for the treatment of infrared singularities arising in electroweak corrections to decay processes at next-to-leading order: the dipole subtraction formalism and the one-cutoff slicing method. The former is extended to the case of decay kinematics which has not been considered in the literature so f...

We update the allowed parameter space of the CP-violating 2HDM with Type II Yukawa couplings, that survives the current experimental and theoretical constraints on the model. For a representative set of allowed parameter points, we study the production of charged Higgs bosons, both at the LHC at 14 TeV and at a possible future hadronic collider at...

We present an analysis of supersymmetric left-right symmetric models with Higgs fields lying in the adjoint representation of SU(2)_R. These models feature a doubly-charged Higgs boson which gets its mass only at the loop level. We present, for the first time, a complete one-loop calculation of this mass and show that contributions that have been n...

The LHC discovery potential of heavy top partners decaying into a top quark and a $Z$ boson is studied in the trilepton channel at 13 TeV in the single production mode. The clean multilepton final state allows to strongly reduce the background contaminations and to reconstruct the $T'$ mass. We show that a simple cut-and-count analysis probes the p...

Phenomenological studies of a CP-violating two-Higgs-doublet Model with type-II Yukawa couplings are presented. In the light of recent LHC data, an update on the viable parameter space that survives both the experimental and theoretical constraints is provided. In addition, the scope of the LHC in exploring this model through the discovery of a cha...

The LHC discovery potential of heavy top partners decaying into a top quark and a $Z$ boson is studied in the trilepton channel at $\sqrt{s}=13$ TeV. The clean multilepton final state allows to strongly reduce the background contaminations and to reconstruct the $T'$ mass. We show that a simple cut-and-count analysis probes the parameter space of a...

We present the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 3--21 June, 2013). Our report includes new computational tool developments, studies of the implications of the Higgs boson discovery on new physics, important signatures for searches for natural new physics at the LHC, new...

In the light of the recent LHC data, we study precision tests sensitive to the violation of lepton universality, in particular the violation of unitarity in neutrino mixing. Keeping all data we find no satisfatory fit, even allowing for violations of unitarity in neutrino mixing. Leaving out sin$^2 \theta_{\scriptsize \mbox{eff}}$ from the hadronic...

The parameter space of the simplest extension of the standard model, is studied in the light of the 125 GeV Higgs boson discovery. The Hill model extends the scalar sector of the standard model with a real singlet, that mixes with the SM Higgs boson. The two-loop SM renormalization group equations are completed with the one-loop Hill equations. Sta...

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 upda...

We describe a simple extension of the standard model, containing a scalar singlet and a triplet fermion. The model can explain the possible enhancement in the decay $H \rightarrow \gamma \gamma$ at the LHC together with the excess found in the Higgs boson search at LEP2. The structure of the model is motivated by a recent argument, that was used to...

The 1-loop renormalization group equations for the minimal Z' models encompassing a type-I seesaw mechanism are studied in the light of the 125 GeV Higgs boson discovery. This model is taken as a benchmark for the general case of singlet extensions of the standard model. The most important result is that negative scalar mixing angles are favoured w...

We consider a model for a Z′-boson coupled only to baryon minus lepton number and hypercharge. Besides the usual right-handed neutrinos, we add a pair of fermions with a fractional lepton charge, which we therefore call leptinos. One of the leptinos is taken to be odd under an additional Z2 charge, the other even. This allows for a natural (inverse...

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 cha...

We discuss the impact on the stau masses of additional D terms in U(1)-extended minimal supersymmetric standard models. We show, explicitly for the B-L supersymmetric standard model, that these contributions can play a crucial role in the explanation of the enhanced diphoton decay rate of a standard-model-like Higgs particle around 125 GeV. Even in...

We study the sensitivity of top pair production at the Large Hadron Collider (LHC) to the nature of an underlying Z' boson, including full tree level standard model background effects and interferences while assuming realistic final state reconstruction efficiencies. We demonstrate that exploiting asymmetry observables represents a promising way to...

In the attempt to fully profile a Z′ boson accessible at the Large Hadron Collider (LHC), we study the sensitivity of di-lepton (for the electron, muon and tauon cases) and di-quark (for the case of the heavy flavours, t and, possibly, b) samples to the nature of the new gauge state, for a one-dimensional class of non-exotic Z′ bosons. Assuming rea...

We study the sensitivity of top pair production at the Large Hadron Collider (LHC) to the nature of an underlying Z' boson, including full tree level standard model background effects and interferences. We demonstrate that exploiting combinations of asymmetry observables will enable one to distinguish between a selection of `benchmark' Z' models wh...

Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC; Results are presented from searches for the standard model Higgs in proton-proton collisions at root s = 7 and 8 TeV in the Compact Muon Solenoid experiment at the LHC, using data samples corresponding to integrated luminosities of up to 5.1 fb(-1) at 7 TeV and 5....

In the attempt to fully profile a $Z'$ boson accessible at the Large Hadron Collider (LHC), we study the sensitivity of di-lepton (for the electron, muon and tauon cases) and di-quark (for the case of the heavy flavours, $t$ and, possibly, $b$) samples to the nature of the new gauge state, for a one-dimensional class of non-exotic $Z'$ bosons. Assu...

We perform a study of the dark matter candidates of a constrained version of the minimal R-parity-conserving supersymmetric model with a gauged U(1)B−L . It turns out that there are four additional candidates for dark matter in comparison to the MSSM: two kinds of neutralino, which either correspond to the gaugino of the U(1)B−L or to a fermionic b...

The SUSY Les Houches Accord (SLHA) 2 extended the first SLHA to include various generalisations of the Minimal Supersymmetric Standard Model (MSSM) as well as its simplest next-to-minimal version. Here, we propose further extensions to it, to include the most general and well-established see-saw descriptions (types I/II/III, inverse, and linear) in...

We present a phenomenological study of a CP-violating two-Higgs-doublet Model with type-II Yukawa couplings at the Large Hadron Collider (LHC). In the light of recent LHC data, we focus on the parameter space that survives the current and past experimental constraints as well as theoretical bounds on the model. Once the phenomenological scenario is...

We study the sensitivity of top-antitop samples produced at all energy stages of the Large Hadron Collider (LHC) to the nature of an underlying Z' boson, in presence of full tree level standard model (SM) background effects and relative interferences. We concentrate on differential mass spectra as well as both spatial and spin asymmetries thereby d...

We present the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 30 May-17 June, 2011). Our report includes new agreements on formats for interfaces between computational tools, new tool developments, important signatures for searches at the LHC, recommendations for presentation of LHC s...

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 mac...

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 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...

A well-motivated framework to naturally introduce neutrino masses is the B-L model, a U(1) extension of the standard model related to the baryon minus lepton gauged number. Besides three right-handed neutrinos, that are included to cancel the anomalies (thereby naturally providing neutrino masses), this model also encompasses a complex scalar for t...

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...

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...

We present the Large Hadron Collider (LHC) discovery potential in the Z' sector of a U(1)_{B-L} enlarged Standard Model also encompassing three heavy Majorana neutrinos, for \sqrt{s}=7 centre-of-mass energy, considering both the Z'_{B-L}\rightarrow e^+e^- and Z'_{B-L}\rightarrow \mu^+\mu^- decay channels. Electrons provide a higher sensitivity to s...

We present some phenomenology of the Higgs sector of the Minimal $B-L$ U(1) Extension of the Standard Model at the Large Hadron Collider. In this model, the existence of an extra gauge boson ($Z'$) and an extra scalar (heavy Higgs) are predicted as naturally related with the breaking of the $B-L$ (baryon minus lepton number) symmetry. For this, we...

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...

We present a collection of signatures for physics beyond the standard model that need to be explored at the LHC. First, are presented various tools developed to measure new particle masses in scenarios where all decays include an unobservable particle. Second, various aspects of supersymmetric models are discussed. Third, some signatures of models...

We present a collection of signatures for physics beyond the standard model that need to be explored at the LHC. First, are presented various tools developed to measure new particle masses in scenarios where all decays include an unobservable particle. Second, various aspects of supersymmetric models are discussed. Third, some signatures of models...

We have derived the unitarity bounds in the high energy limit for the minimal B-L extension of the standard model by analyzing the full class of Higgs and would-be Goldstone boson two-to-two scatterings at tree level. Moreover, we have investigated how these limits could vary at some lower critical value of the energy.

We present the complete set of renormalization group equations at one loop for the nonexotic 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 neutrino per generation. We then pursue the numerical study of the pure B-L model, deriving the trivial...

This is the summary and introduction to the proceedings contributions for the Les Houches 2009 "Tools and Monte Carlo" working group. Comment: 144 Pages. Workshop site http://wwwlapp.in2p3.fr/conferences/LesHouches/Houches2009/ . Conveners were Butterworth, Maltoni, Moortgat, Richardson, Schumann and Skands

This is the summary and introduction to the proceedings contributions for the Les Houches 2009 "Tools and Monte Carlo" working group.

We present the Large Hadron Collider (LHC) discovery potential in the Z′ sector of a \(U(1)_{B\mbox{--}L}\) 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 \(Z'_{B\mbox{--}L}\rightarrow e^{+}e^{-}\) and \(Z'...

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. We carry out a detailed comparison between the discovery regions mapped over a two-dimensional configuration space ($Z'$ mass and coupling) at the Large...

We present the Large Hadron Collider (LHC) discovery potential in the $Z'$ and heavy neutrino sectors of a $U(1)_{B-L}$ enlarged Standard Model also encompassing three heavy Majorana neutrinos. This model exhibits novel signatures at the LHC, the most interesting arising from a $Z'$ decay chain involving heavy neutrinos, eventually decaying into le...

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 emergi...

We present the Large Hadron Collider (LHC) discovery potential in the $Z'$ and heavy neutrino sectors of a $U(1)_{B-L}$ enlarged Standard Model also encompassing three heavy Majorana neutrinos. This model exhibits novel signatures at the LHC, the most interesting arising from a $Z'$ decay chain involving heavy neutrinos, eventually decaying into le...