arXiv subjects

W. Porod

Publications and source records attributed to W. Porod.

At least 19 recordsLinked to original sources

arXiv2026

Phenomenology of electroweak spin-1 resonances

Composite Higgs models with a fermionic UV completion predict the existence of various bound states. We investigate models containing SU(2)$_L\times$SU(2)$_R$ as part of the unbroken global subgroup in the new strong sector. These models predict that there are two neutral and one charged spin-1 resonances mixing seizable with the SM vector bosons. These can be singly produced at the LHC. We explore their LHC phenomenology and demonstrate that there are still viable scenarios consistent with existing LHC data where the masses of these states can be as low as about 1.5 TeV.

hep-ph↗

arXiv2025

Phenomenology of Spin-1 resonances at the LH

Spin-1 resonances are among the states predicted by composite Higgs models and one expects them the have masses in the range of a few TeV. We focus here on models based on an underlying gauge-fermion description which predict QCD-coloured vector and axial-vector states as well as states charged under the electroweak gauge groups. The former can come as triplet, sextet and octet representation depending on the model details. All models considered have a colour octet vector state in common which can be singly produced at hadron colliders as it mixes with the gluon. We summarize here their LHC phenomenology and comment also on aspects relevant for future colliders.

hep-ph↗

arXiv2023

Renormalized equations of motions for scalars and fermions in the 2PI formalism

We present on shell-scheme for the 2PI formalism with a particular focus on the renormalized equations of motion. We first revisit the so-called Hartree approximation where we give the counterterms for both the broken and unbroken phase. Moreover, we give explicit formulas for the renormalized three- and four-point functions in the broken phase. We then turn to the sunset approximation, with only scalars and then including fermions. We give explicit formulas for the wavefunction and mass counterterms. Moreover, we show that, in particular, the two-point functions can be obtained numerically in a fast converging scheme even for large couplings of order one.

hep-ph↗

arXiv2023

Higgs-mass predictions in the MSSM and beyond

Predictions for the Higgs masses are a distinctive feature of supersymmetric extensions of the Standard Model, where they play a crucial role in constraining the parameter space. The discovery of a Higgs boson and the remarkably precise measurement of its mass at the LHC have spurred new efforts aimed at improving the accuracy of the theoretical predictions for the Higgs masses in supersymmetric models. The "Precision SUSY Higgs Mass Calculation Initiative" (KUTS) was launched in 2014 to provide a forum for discussions between the different groups involved in these efforts. This report aims to present a comprehensive overview of the current status of Higgs-mass calculations in supersymmetric models, to document the many advances that were achieved in recent years and were discussed during the KUTS meetings, and to outline the prospects for future improvements in these calculations.

hep-ph↗

arXiv2023

Accommodating muon $\boldsymbol{(g-2)}$ and leptogenesis in a scotogenic model

We present a detailed study of a scotogenic model accommodating dark matter, neutrino masses and the anomalous magnetic moment of the muon while being consistent with the existing constraints on flavour violating decays of the leptons. Moreover, this model offers the possibility to explain the baryon asymmetry of the Universe via leptogenesis. We determine the viable regions of the model's parameter space in view of dark matter and flavour constraints using a Markov Chain Monte Carlo setup combined with a particular procedure to accommodate neutrino masses and the anomalous magnetic moment of the muon at the same time. We also discuss briefly the resulting collider phenomenology.

hep-ph↗

arXiv2022

Exploring extended Higgs sectors via pair production at the LHC

Higgs sectors extended by electroweakly charged scalars can be explored by scalar pair production at the LHC. We consider a fermiophobic scenario, with decays into a pair of gauge bosons, and a fermiophilic one, with decays into top and bottom quarks. After establishing the current bounds on simplified models, we focus on an SU(5)/SO(5) composite Higgs model. This first exploration demonstrates the need for dedicated searches at current and future colliders.

hep-ph↗

arXiv2021

Roadmap on Spin-Wave Computing

Magnonics is a field of science that addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operations in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors that covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with Boolean digital data, unconventional approaches like neuromorphic computing, and the progress towards magnon-based quantum computing. The article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of the current challenges and the outlook of the further development of the research directions.

physics.app-ph↗

arXiv2021

Resolving a challenging supersymmetric low-scale seesaw scenario at the ILC

We investigate a scenario inspired by natural supersymmetry, where neutrino data is explained within a low-scale seesaw scenario. For this the Minimal Supersymmetric Standard Model is extended by adding light right-handed neutrinos and their superpartners, the R-sneutrinos. Moreover, we consider the lightest neutralinos to be Higgsino-like. We first update a previous analysis and assess to which extent does existing LHC data constrain the allowed slepton masses. Here we find scenarios where sleptons with masses as low as 175 GeV are consistent with existing data. However, we also show that the upcoming run will either discover or rule out sleptons with masses of 300 GeV, even for these challenging scenarios. We then take a scenario which is on the borderline of observability of the upcoming LHC run assuming a luminosity of 300 fb$^{-1}$. We demonstrate that a prospective international $e^+ e^-$ linear collider with a center of mass energy of 1 TeV will be able to discover sleptons in scenarios which are difficult for the LHC. Moreover, we also show that a measurement of the spectrum will be possible within 1-3 percent accuracy.

hep-ph↗

arXiv2020

Revisiting (s)neutrino dark matter in natural SUSY

We study natural supersymmetric scenarios with light right-handed neutrino superfields, and consider the possibility of having either a neutrino or a sneutrino as a dark matter candidate. For the former, we evaluate the possibility of having SUSY corrections on the $ν_4\toν_\ellγ$ decay rate, such that the NuStar bounds are relaxed. We find that corrections are too small. For sneutrino dark matter, we consider thermal and non-thermal production, taking into account freeze-out, freeze-in and super-WIMP mechanisms. For the non-thermal case, we find that the $\tildeν_R$ can reproduce the observed relic density by adjusting the R-sneutrino mass and Yukawa couplings. For the thermal case, we find the need to extend the model in order to enhance sneutrino annihilations, which we exemplify in a model with an extended gauge symmetry.

hep-ph↗

arXiv2020

Les Houches 2019 Physics at TeV Colliders: New Physics Working Group Report

This report presents the activities of the `New Physics' working group for the `Physics at TeV Colliders' workshop (Les Houches, France, 10--28 June, 2019). These activities include studies of direct searches for new physics, approaches to exploit published data to constrain new physics, as well as the development of tools to further facilitate these investigations. Benefits of machine learning for both the search for new physics and the interpretation of these searches are also presented.

hep-ph↗

arXiv2018

Precise determination of the neutral Higgs boson masses in the MSSM

We present the implementation of the radiative corrections of the Higgs sector in three public computer codes for the evaluation of the particle spectrum in the Minimal Supersymmetric Standard Model, Softsusy, Spheno and SuSpect. We incorporate the full one-loop corrections to the Higgs boson masses and the electroweak symmetry breaking conditions, as well as the two-loop corrections controlled by the strong gauge coupling and the Yukawa couplings of the third generation fermions. We include also the corrections controlled by the tau Yukawa coupling that we derived for completeness. The computation is consistently performed in the DRbar renormalisation scheme. In a selected number of MSSM scenarios, we study the effect of these corrections and analyse the impact of some higher order effects. By considering the renormalisation scheme and scale dependence, and the effect of the approximation of zero external momentum in the two-loop corrections, we estimate the theoretical uncertainty on the lighter Higgs boson mass to be 3 to 5 GeV. The uncertainty on Mh due to the experimental error in the measurement of the SM input parameters is approximately of the same size. Finally, we discuss the phenomenological consequences, using the latest value of the top quark mass. We find, in particular, that the most conservative upper bound on the lighter Higgs boson mass in the general MSSM is Mh < 152 GeV and that there is no lower bound on the parameter tan(beta) from non-observation of the MSSM Higgs bosons at LEP2.

hep-ph↗

arXiv2018

Les Houches 2017: Physics at TeV Colliders New Physics Working Group Report

We present the activities of the `New Physics' working group for the `Physics at TeV Colliders' workshop (Les Houches, France, 5--23 June, 2017). Our report includes new physics studies connected with the Higgs boson and its properties, direct search strategies, reinterpretation of the LHC results in the building of viable models and new computational tool developments.

hep-ph↗

arXiv2016

Les Houches 2015: Physics at TeV colliders - new physics working group report

We present the activities of the 'New Physics' working group for the 'Physics at TeV Colliders' workshop (Les Houches, France, 1-19 June, 2015). Our report includes new physics studies connected with the Higgs boson and its properties, direct search strategies, reinterpretation of the LHC results in the building of viable models and new computational tool developments. Important signatures for searches for natural new physics at the LHC and new assessments of the interplay between direct dark matter searches and the LHC are also considered.

hep-ph↗

arXiv2015

Natural SUSY: LHC and Dark Matter direct detection experiments interplay

Natural SUSY scenarios with a low value of the $μ$ parameter, are characterised by a higgsino-like dark matter candidate, and a compressed spectrum for the lightest higgsinos. We explore the prospects for probing this scenario at the 13 TeV stage of the LHC via monojet searches, with various integrated luminosity options, and demonstrate how these results are affect by different assumptions on the achievable level of control on the experimental systematic uncertainties. The complementarity between collider and direct detection experiments (present and future) is also highlighted.

hep-ph↗

arXiv2015

Physics at the e+ e- Linear Collider

A comprehensive review of physics at an e+e- Linear Collider in the energy range of sqrt{s}=92 GeV--3 TeV is presented in view of recent and expected LHC results, experiments from low energy as well as astroparticle physics.The report focuses in particular on Higgs boson, Top quark and electroweak precision physics, but also discusses several models of beyond the Standard Model physics such as Supersymmetry, little Higgs models and extra gauge bosons. The connection to cosmology has been analyzed as well.

hep-ph↗

arXiv2014

Lepton flavor violation in low-scale seesaw models: SUSY and non-SUSY contributions

Taking the supersymmetric inverse seesaw mechanism as the explanation for neutrino oscillation data, we investigate charged lepton flavor violation in radiative and 3-body lepton decays as well as in neutrinoless $μ-e$ conversion in muonic atoms. In contrast to former studies, we take into account all possible contributions: supersymmetric as well as non-supersymmetric. We take CMSSM-like boundary conditions for the soft supersymmetry breaking parameters. We find several regions where cancellations between various contributions exist, reducing the lepton flavor violating rates by an order of magnitude compared to the case where only the dominant contribution is taken into account. This is in particular important for the correct interpretation of existing data as well as for estimating the reach of near future experiments where the sensitivity will be improved by one to two orders of magnitude. Moreover, we demonstrate that ratios like BR($τ\to 3 μ$)/BR($τ\to μe^+ e^-$) can be used to determine whether the supersymmetric contributions dominate over the $W^\pm$ and $H^\pm$ contributions or vice versa.

hep-ph↗

arXiv2014

Constraining the Natural MSSM through tunneling to color-breaking vacua at zero and non-zero temperature

We re-evaluate the constraints on the parameter space of the minimal supersymmetric standard model from tunneling to charge- and/or color-breaking minima, taking into account thermal corrections. We pay particular attention to the region known as the Natural MSSM, where the masses of the scalar partners of the top quarks are within an order of magnitude or so of the electroweak scale. These constraints arise from the interaction between these scalar tops and the Higgs fields, which allows the possibility of parameter points having deep charge- and color-breaking true vacua. In addition to requiring that our electro-weak-symmetry-breaking, yet QCD- and electromagnetism-preserving vacuum has a sufficiently long lifetime at zero temperature, also demanding stability against thermal tunneling further restricts the allowed parameter space.

hep-ph↗

arXiv2014

Flavour violating bosonic squark decays at LHC

We study quark flavour violation (QFV) in the squark sector of the Minimal Supersymmetric Standard Model (MSSM). We assume mixing between the second and the third squark generations, i.e. sc_R-st_{L,R} mixing mixing. We focus on QFV effects in bosonic squark decays, in particular on the decay into the lightest Higgs boson h0, su_2 -> su_1 h0, where su_{1,2} are the lightest up-type squarks. We show that the branching ratio of this QFV decay can be quite large (up to 50 %) due to large QFV trilinear couplings, and large sc_R-st_{L, R} and st_L-st_R mixing, despite the strong constraints on QFV from B meson data. This can result in characteristic QFV final states with significant rates at LHC (14 TeV), such as pp -> gluino gluino X -> t + h0 + 3jets + Etmiss + X and pp -> gluino gluino X -> t t (or tbar tbar) + h0 + 2jets + Etmiss + X. The QFV bosonic squark decays can have an influence on the squark and gluino searches at LHC.

hep-ph↗