arXiv subjects

Benjamin Fuks

Publications and source records attributed to Benjamin Fuks.

At least 109 records · Page 6Linked to original sources

arXiv2018

Investigating the scalar sector of left-right symmetric models with leptonic probes

We investigate the potential collider signatures of singly-charged and doubly-charged Higgs bosons such as those arising in minimal left-right symmetric models. Focusing on multileptonic probes in the context of the high-luminosity run of the Large Hadron Collider, we separately assess the advantages of the four-leptonic and trileptonic final states for a representative benchmark setup designed by considering a large set of experimental constraints. Our study establishes possibilities of identifying singly-charged and doubly-charged scalars at the Large Hadron Collider with a large significance, for luminosity goals expected to be reached during the high-luminosity phase of the Large Hadron Collider. We generalise our results and demonstrate that existing limits can in principle be pushed much further in the heavy mass regime.

hep-ph↗

arXiv2018

Top-philic Vector-Like Portal to Scalar Dark Matter

We investigate the phenomenology of scalar singlet dark matter candidates that couple dominantly to the Standard Model via a Yukawa interaction with the top quark and a colored vector-like fermion. We estimate the viability of this vector-like portal scenario with respect to the most recent bounds from dark matter direct and indirect detection, as well as to dark matter and vector-like mediator searches at colliders. Moreover, we take QCD radiative corrections into account in all our theoretical calculations. This work complements analyses related both to models featuring a scalar singlet coupled through a vector-like portal to light quarks, and to scenarios in which the dark matter is a Majorana singlet coupled to the Standard Model through scalar colored particles (akin to simplified models inspired by supersymmetry). Our study puts especially forward the complementarity of different search strategies from different contexts, and we show that current experiments allow for testing dark matter masses ranging up to 700 GeV and mediator masses ranging up to 6 TeV.

hep-ph↗

arXiv2018

Proceedings of the first MadAnalysis 5 workshop on LHC recasting in Korea

We present the activities performed during the first MadAnalysis 5 workshop on LHC recasting that has been organized at High 1 (Gangwon privince, Korea) on August 20-27, 2017. This report includes details on the implementation in the MadAnalysis 5 framework of eight ATLAS and CMS analyses, as well as a description of the corresponding validation and the various issues that have been observed.

hep-ph↗

arXiv2018

Seeking Heavy Higgs Bosons through Cascade Decays

We investigate the LHC discovery prospects for a heavy Higgs boson decaying into the Standard Model Higgs boson and additional weak bosons. We consider a generic model-independent new physics configuration where this decay proceeds via a cascade involving other intermediate scalar bosons and focus on an LHC final-state signature comprised either of four b-jets and two charged leptons or of four charged leptons and two b-jets. We design two analyses of the corresponding signals, and demonstrate that a 5σ discovery at the 14 TeV LHC is possible for various combinations of the parent and daughter Higgs-boson masses. We moreover find that the Standard Model backgrounds can be sufficiently rejected to guarantee the reconstrution of the parent Higgs boson mass. We apply our analyses to the Type-II Two-Higgs-Doublet Model and identify the regions of the parameter space to which the LHC is sensitive.

hep-ph↗

arXiv2018

Realistic simplified gaugino-higgsino models in the MSSM

We present simplified MSSM models for light neutralinos and charginos with realistic mass spectra and realistic gaugino-higgsino mixing, that can be used in experimental searches at the LHC. The formerly used naive approach of defining mass spectra and mixing matrix elements manually and independently of each other does not yield genuine MSSM benchmarks. We suggest the use of less simplified, but realistic MSSM models, whose mass spectra and mixing matrix elements are the result of a proper matrix diagonalisation. We propose a novel strategy targeting the design of such benchmark scenarios, accounting for user-defined constraints in terms of masses and particle mixing. We apply it to the higgsino case and implement a scan in the four relevant underlying parameters {μ, tanβ, M_1, M_2} for a given set of light neutralino and chargino masses. We define a measure for the quality of the obtained benchmarks, that also includes criteria to assess the higgsino content of the resulting charginos and neutralinos. We finally discuss the distribution of the resulting models in the MSSM parameter space as well as their implications for supersymmetric dark matter phenomenology.

hep-ph↗

arXiv2018

Loopholes in $Z^\prime$ searches at the LHC: exploring supersymmetric and leptophobic scenarios

Searching for heavy vector bosons $Z^\prime$, predicted in models inspired by Grand Unification Theories, is among the challenging objectives of the LHC. The ATLAS and CMS collaborations have looked for $Z^\prime$ bosons assuming that they can decay only into Standard Model channels, and have set exclusion limits by investigating dilepton, dijet and to a smaller extent top-antitop final states. In this work we explore possible loopholes in these $Z^\prime$ searches by studying supersymmetric as well as leptophobic scenarios. We demonstrate the existence of realizations in which the $Z^\prime$ boson automatically evades the typical bounds derived from the analyses of the Drell-Yan invariant-mass spectrum. Dileptonic final states can in contrast only originate from supersymmetric $Z^\prime$ decays and are thus accompanied by additional effects. This feature is analyzed in the context of judiciously chosen benchmark configurations, for which visible signals could be expected in future LHC data with a $4σ-7σ$ significance. Our results should hence motivate an extension of the current $Z^\prime$ search program to account for supersymmetric and leptophobic models.

hep-ph↗

arXiv2017

Probing CP-violating Higgs and gauge boson couplings in the Standard Model effective field theory

We study the phenomenological consequences of several $CP$-violating structures that could arise in the Standard Model effective field theory framework. Focusing on operators involving electroweak gauge and/or Higgs bosons, we derive constraints originating from Run I LHC data. We then study the capabilities of the present and future LHC runs at higher energies to further probe associated CP-violating phenomena and we demonstrate how differential information can play a key role. We consider both traditional four-lepton probes of CP-violation in the Higgs sector and novel new physics handles based on varied angular and non-angular observables.

hep-ph↗

arXiv2017

Cornering pseudoscalar-mediated dark matter with the LHC and cosmology

Models in which dark matter particles communicate with the visible sector through a pseudoscalar mediator are well-motivated both from a theoretical and from a phenomenological standpoint. With direct detection bounds being typically subleading in such scenarios, the main constraints stem either from collider searches for dark matter, or from indirect detection experiments. However, LHC searches for the mediator particles themselves can not only compete with -- or even supersede -- the reach of direct collider dark matter probes, but they can also test scenarios in which traditional monojet searches become irrelevant, especially when the mediator cannot decay on-shell into dark matter particles or its decay is suppressed. In this work we perform a detailed analysis of a pseudoscalar-mediated dark matter simplified model, taking into account a large set of collider constraints and concentrating on the parameter space regions favoured by cosmological and astrophysical data. We find that mediator masses above 100-200~GeV are essentially excluded by LHC searches in the case of large couplings to the top quark, while forthcoming collider and astrophysical measurements will further constrain the available parameter space.

hep-ph↗

arXiv2017

Differentiating $U(1)^\prime$ supersymmetric models with right sneutrino and neutralino dark matter

We perform a detailed analysis of dark matter signals of supersymmetric models containing an extra $U(1)^\prime$ gauge group. We investigate scenarios in which either the right sneutrino or the lightest neutralino are phenomenologically acceptable dark matter candidates and we explore the parameter spaces of different supersymmetric realisations featuring an extra $U(1)^\prime$. We impose consistency with low energy observables, with known mass limits for the superpartners and $Z^\prime$ bosons, as well as with Higgs boson signal strengths, and we moreover verify that predictions for the anomalous magnetic moment of the muon agree with the experimental value and require that the dark matter candidate satisfies the observed relic density and direct and indirect dark matter detection constraints. For the case where the sneutrino is the dark matter candidate, we find distinguishing characteristics among different $U(1)^\prime$ mixing angles. If the neutralino is the lightest supersymmetric particle, its mass is heavier than that of the light sneutrino in scenarios where the latter is a dark matter candidate, the parameter space is less restricted and differentiation between models is more difficult. We finally comment on the possible collider tests of these models.

hep-ph↗

arXiv2017

Probing vector-like quark models with Higgs-boson pair production

We investigate Higgs-boson pair production at the LHC when the final state system arises from decays of vector-like quarks coupling to the Higgs boson and the Standard Model quarks. Our phenomenological study includes next-to-leading-order QCD corrections, which are important to guarantee accurate predictions, and focuses on a detailed analysis of a di-Higgs signal in the four $b$-jet channel. Whereas existing Run II CMS and ATLAS analyses are not specifically designed for probing non-resonant, vector-like-quark induced, di-Higgs production, we show that they nevertheless offer some potential for these modes. We then investigate the possibility of distinguishing between the various di-Higgs production mechanisms by exploiting the kinematic properties of the signal.

hep-ph↗

arXiv2017

Scrutinizing the Higgs quartic coupling at a future 100 TeV proton-proton collider with taus and b-jets

The Higgs potential consists of an unexplored territory in which the electroweak symmetry breaking is triggered, and it is moreover directly related to the nature of the electroweak phase transition. Measuring the Higgs boson cubic and quartic couplings, or getting equivalently information on the exact shape of the Higgs potential, is therefore an essential task. However, direct measurements beyond the cubic self-interaction of the Higgs boson consist of a huge challenge, even for a future proton-proton collider expected to operate at a center-of-mass energy of 100 TeV. We present a novel approach to extract model-independent constraints on the triple and quartic Higgs self-coupling by investigating triple Higgs-boson hadroproduction at a center-of-mass energy of 100 TeV, focusing on the $ττb \bar{b} b \bar{b}$ channel that was previously overlooked due to a supposedly too large background. It is thrown into sharp relief that the assist from transverse variables such as $m_{T2}$ and a boosted configuration ensures a high signal sensitivity. We derive the luminosities that would be required to constrain given deviations from the Standard Model in the Higgs self-interactions, showing for instance that a $2σ$ sensitivity could be achieved for an integrated luminosity of 30 ab$^{-1}$ when Standard Model properties are assumed. With the prospects of combining these findings with other triple-Higgs search channels, the Standard Model Higgs quartic coupling could in principle be reached with a significance beyond the $3σ$ level.

hep-ph↗

arXiv2017

A Comprehensive Framework for Studying $W'$ and $Z'$ Bosons at Hadron Colliders with Automated Jet Veto Resummation

The production of high-mass, color-singlet particles in hadron colliders is universally accompanied by initial state QCD radiation that is predominantly soft with respect to the hard process scale $Q$ and/or collinear with respect to the beam axis. At TeV-scale colliders, this is in contrast to top quark and multijet processes, which, by definition, are hard and central. Consequently, vetoing events with jets possessing transverse momenta above $p_T^{\rm Veto}$ in searches for new color-singlet states can efficiently reduce non-singlet backgrounds, thereby increasing experimental sensitivity. To quantify this generic observation, we investigate the production and leptonic decay of a Sequential Standard Model $W'$ boson at the 13 TeV LHC. We systematically consider signal and background processes at next-to-leading-order (NLO) in QCD with parton shower (PS) matching; for color-singlet channels, we resum Sudakov logarithms of the form $α_s^j(p_T^{\rm Veto})\log^k(Q/p_T^{\rm Veto})$ up to next-to-next-to-leading logarithmic accuracy (NNLL) with NLO matching. We obtain our results using the MadGraph5aMC@NLO and MadGraph5aMC@NLO-SCET frameworks, respectively. Associated FeynRules model files capable of handling NLO+PS- and NLO+NNLL-accurate computations are publicly available. We find that within their given uncertainties, both the NLO+PS and NLO+NNLL(veto) calculations give accurate and consistent predictions. Consequently, jet vetoes applied to color-singlet processes can be reliably modeled at the NLO+PS level. With respect to a $b$-jet veto of $p_{T}^{\rm Veto} = 30$ GeV, flavor-agnostic vetoes of $p_{T}^{\rm Veto} = 30-40$ GeV can further reduce single top and $t\overline{t}$ rates by a factor of 2-50 at a mild cost of the signal rate. Jet vetoes can increase signal-to-noise ratios by roughly 10\% for light $W'$ boson masses of 30-50 GeV and 25\%-250\% for masses of 300-800 GeV.

hep-ph↗

arXiv2017

Resonant slepton production and right sneutrino dark matter in left-right supersymmetry

Right-handed sneutrinos are natural components of left-right symmetric supersymmetric models where the gauge sector is extended to include right-handed weak interactions. Unlike in other models where right-handed sneutrinos are gauge singlets, here the right sneutrino is part of a doublet and could be a dark matter candidate whose annihilation proceeds via gauge interactions. We investigate this possibility, and find that relic density, low-energy observable and direct supersymmetry search constraints can be satisfied when the lightest supersymmetric particle is a right-handed sneutrino. We introduce benchmarks for left-right supersymmetric realizations where either a sneutrino or a neutralino is the lightest superpartner. We then study the LHC signals arising through resonant right-handed slepton production via a $W_R$ gauge-boson exchange that lead to final states enriched in leptons, additionally containing a large amount of missing transverse momentum, and featuring a low jet multiplicity. We find that such a resonant production would boost the chances of discovering these weakly interacting supersymmetric particles for a mass range extending beyond 1 TeV already with a luminosity of 100 fb$^{-1}$. Finally, we compare sneutrino versus neutralino scenarios, and comment on differences with other sneutrino dark matter models.

hep-ph↗

arXiv2017

Electroweak Higgs boson production in the standard model effective field theory beyond leading order in QCD

We study the impact of dimension-six operators of the standard model effective field theory relevant for vector-boson fusion and associated Higgs boson production at the LHC. We present predictions at the next-to-leading order accuracy in QCD that include matching to parton showers and that rely on fully automated simulations. We show the importance of the subsequent reduction of the theoretical uncertainties in improving the possible discrimination between effective field theory and standard model results, and we demonstrate that the range of the Wilson coefficient values allowed by a global fit to LEP and LHC Run~I data can be further constrained by LHC Run~II future results.

hep-ph↗

arXiv2017

QCD next-to-leading-order predictions matched to parton showers for vector-like quark models

Vector-like quarks are featured by a wealth of beyond the Standard Model theories and are consequently an important goal of many LHC searches for new physics. Those searches, as well as most related phenomenological studies, however rely on predictions evaluated at the leading-order accuracy in QCD and consider well-defined simplified benchmark scenarios. Adopting an effective bottom-up approach, we compute next-to-leading-order predictions for vector-like-quark pair-production and single production in association with jets, with a weak or with a Higgs boson in a general new physics setup. We additionally compute vector-like-quark contributions to the production of a pair of Standard Model bosons at the same level of accuracy. For all processes under consideration, we focus both on total cross sections and on differential distributions, most these calculations being performed for the first time in our field. As a result, our work paves the way to precise extraction of experimental limits on vector-like quarks thanks to an accurate control of the shapes of the relevant observables and emphasize the extra handles that could be provided by novel vector-like-quark probes never envisaged so far

hep-ph↗

arXiv2017

Exploring the squark flavour structure of the MSSM

We present an extensive study of the MSSM parameter space allowing for general generation mixing in the squark sector. Employing an MCMC algorithm, we establish the parameter ranges which are allowed with respect to various experimental and theoretical constraints. Based on this analysis, we propose benchmark scenarios for future studies. Moreover, we discuss aspects of signatures at the LHC.

hep-ph↗

arXiv2016

Monojet searches for momentum-dependent dark matter interactions

We consider minimal dark matter scenarios featuring momentum-dependent couplings of the dark sector to the Standard Model. We derive constraints from existing LHC searches in the monojet channel, estimate the future LHC sensitivity for an integrated luminosity of 300 fb$^{-1}$, and compare with models exhibiting conventional momentum-independent interactions with the dark sector. In addition to being well motivated by (composite) pseudo-Goldstone dark matter scenarios, momentum-dependent couplings are interesting as they weaken direct detection constraints. For a specific dark matter mass, the LHC turns out to be sensitive to smaller signal cross-sections in the momentum-dependent case, by virtue of the harder jet transverse-momentum distribution.

hep-ph↗

arXiv2016

Investigating the jet activity accompanying the production at the LHC of a massive scalar particle decaying into photons

We study the jet activity that accompanies the production by gluon fusion of a new physics scalar particle decaying into photons at the LHC. In the considered scenarios, both the production and decay mechanisms are governed by loop-induced interactions involving a heavy colored state. We show that the presence of large new physics contributions to the inclusive diphoton invariant-mass spectrum always implies a significant production rate of non-standard diphoton events containing extra hard jets. We investigate the existence of possible handles that could provide a way to obtain information on the underlying physics behind the scalar resonance, and this in a wide mass window.

hep-ph↗