arXiv subjects

Wojciech Kotlarski

Publications and source records attributed to Wojciech Kotlarski.

At least 19 recordsLinked to original sources

arXiv2026

Phenomenology of the Higgs sector from Reduction of Couplings in the Type-II 2HDM

The idea of reduction of couplings provides a systematic procedure to search for relations among seemingly unrelated parameters of a renormalizable theory. As a consequence, such reduced theories exhibit more constrained parameter spaces. Motivated by this, in this work we perform a precise phenomenological analysis of the Higgs sector of a version of the Type-II 2HDM on which the idea of reduction of couplings has been applied. We compute Higgs boson masses and decay widths and confront them with current experimental measurements. Compared to the previous study, apart from the inclusion of actual experimental constraints on production and decay rates of Higgs bosons, we also include all model parameters in the RGE running as well as one- and two-loop threshold corrections and two-loop RGE running from the high scale. Furthermore, Higgs boson masses are now computed at the one-loop level. Top quark mass, which is an important prediction of the reduction framework, is now evaluated including previously missing sub-leading one-loop contributions, with an addition of up to four-loop pure-QCD corrections.

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arXiv2026

GUT-induced FCC signatures of the LUX-ZEPLIN event

The recent observation of an event with large recoil energy at LUX-ZEPLIN has found a possible explanation in terms of the inelastic scattering of a pseudo-Dirac particle like the Higgsino of the MSSM. For pseudo-Dirac dark matter, the mass splitting $δm$ is correlated with the mass of some heavier states. While rough dimensional considerations seem to indicate mass ranges of the heavy particles hopelessly out of reach even at future colliders, we point out that this is not the case in GUT-induced scenarios. Working with a specific model based on SU(6), we show that the experimentally favored $δm$ implies the presence of a $Z'$ gauge boson with a mass in the 10s of TeV. We derive the predicted $Z'$ signal in the dilepton channel and we confront it with the sensitivity of the FCC-$hh$ to $Z'$ resonances. We show that the $Z'$ falls squarely in reach of the early discovery potential of the FCC-$hh$.

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arXiv2026

From Lagrangian to Higgs physics constraints for SUSY and non-SUSY models: interfacing FlexibleSUSY with HiggsTools and Lilith

FlexibleSUSY is a framework for an automated calculation of observables in user-defined models of a Beyond the Standard Model (BSM) physics, starting from the model's field content and its Lagrangian. Among a plethora of observables it is capable of calculating are the high precision predictions for Higgs bosons decay widths. Building on these previous developments we present here an interface between FlexibleSUSY and HiggsTools/Lilith. Combined with other FlexibleSUSY capabilities this extension provides a fully automatized tool chain leading directly from a user-defined BSM model to the state-of-the-art validation of the global agreement of a BSM Higgs sector with experimental measurements. We demonstrate this extension on a handful of phenomenologically relevant examples: a CP-conserving version of the Type-II Two Higgs Doublet Model, the CP-violating Next-to-Minimal Supersymmetric Standard Model and the Minimal R-symmetric Supersymmetric Standard Model. These examples show the power of FlexibleSUSY when applied to supersymmetric and non-supersymmetric models, both with and without CP-violation, and illustrate the handling of invisible and undetected decay widths.

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arXiv2025

Towards automatizing Higgs decays in BSM models at one-loop in the decoupling renormalization scheme

We propose the use of a decoupling renormalization scheme in the calculation of NLO corrections to SM-like Higgs boson decays in the beyond the Standard Model models. The advantage of this particular scheme is its decoupling property in the presence of a heavy BSM physics and the possibility to directly include known higher-order Standard Model corrections. We illustrate the use of this scheme by analysing the $h \to μ^+ μ^-$ decay in a simple Standard Model extension by an $S_1$ leptoquark.

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arXiv2024

Interpreting 95 GeV di-photon/$b\bar{b}$ excesses as a lightest Higgs boson of the MRSSM

The Minimal R-symmetric Supersymmetric Standard Model (MRSSM) is a well motivated BSM model which can accommodate the observed 125 GeV Higgs boson in agreement with electroweak precision observables, in particular with the $W$ boson mass and $T$ parameter. In the 2016 paper we showed that the SM-like 125 GeV Higgs state can be also realised as the second-to-lightest scalar of the MRSSM, leaving room for another sub-100 GeV state. Motivated by the recent ATLAS and CMS observation of the di-photon excess at a mass of around 95 GeV we investigate the possibility whether this could be the lightest CP-even MRSSM scalar in a variation of our benchmarks presented in the 2016 work. We show that such a state can also simultaneously explain the excess in the $b\bar{b}$ final state observed around the same mass value at LEP. Due to the R-symmetric nature of the model, a light singlet-like Higgs state leads necessarily to a light bino-singlino Dirac dark matter candidate, which can give a correct relic density while evading current experimental bounds. Dark matter and LHC searches place further bounds on this scenario and point to parameter regions which are viable and of interest for the LHC Run III and upcoming dark matter experiments.

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arXiv2024

Squark production with R-symmetry beyond NLO at the LHC

The Minimal R-symmetric Supersymmetric Standard Model (MRSSM) provides a realisation of supersymmetry in which the parameter space is less constrained by the current LHC data than in the simplest supersymmetric scenarios. In the present paper, we obtain the most precise theoretical predictions in the MRSSM for squark production at the LHC, enabling accurate interpretations of LHC data in terms of the MRSSM. We perform threshold resummation of soft gluon corrections to the total cross sections for the production of squark-(anti)squark pairs at the LHC in the MRSSM framework. The resummation is carried out using the direct QCD method and reaches the next-to-next-to-leading-logarithmic (NNLL) accuracy, which requires calculating the one-loop matching coefficients in the relevant production channels. The resummed cross sections are then matched to the available NLO results and evaluated for $\sqrt{S}=13.6$ TeV. Compared with the Minimal Supersymmetric Standard Model (MSSM), the cross sections in the MRSSM can be significantly reduced, implying less stringent limits on squark and gluino masses. Our results carry significant implications for exploring the viability of supersymmetry at the LHC. The results of our calculation are publicly available as a numerical package.

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arXiv2024

Constraining Higgs sectors of BSM models -- the case of 95 GeV "Higgs"

In view of lack of the direct experimental evidence for a Beyond the Standard Model (BSM) physics, accommodating a SM-like Higgs boson is on the most important constraints that a BSM model must fulfill. Already for some time the FlexibleSUSY spectrum generator generator allowed for a reliable prediction of masses and decay patterns of the BSM Higgs boson in a large class of user defined supersymmetric and non-supersymmetric models. However, no easy way to compare those predictions with experimental data existed. To that end we present here an interface between FlexibleSUSY and HiggsTools, a computer program assessing in a statistically meaningful way consistency of a BSM Higgs sector with experiments. Motivated by the recent ATLAS and CMS observation of the di-photon excess at a mass of $\sim$95 GeV we demonstrate the capabilities of our framework by investigating whether the observed low mass excesses around 95 GeV seen in the data can be explained as the lightest scalar of the Minimal R-symmetric Supersymmetric Standard Model, without spoiling the SM-like properties of the second-to-lightest state. We also briefly comment on the light dark matter candidate which is a necessarily ingredient of such a setup.

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arXiv2024

FlexibleSUSY extended to automatically compute physical quantities in any Beyond the Standard Model theory: Charged Lepton Flavor Violation processes, Higgs decays, and user-defined observables

FlexibleSUSY is a framework for the automated computation of physical quantities (observables) in models beyond the Standard Model (BSM). This paper describes an extension of FlexibleSUSY which allows to define and add new observables that can be enabled and computed in applicable user-defined BSM models. The extension has already been used to include Charged Lepton Flavor Violation (CLFV) observables, but further observables can now be added straightforwardly. The paper is split into two parts. The first part is non-technical and describes from the user's perspective how to enable the calculation of predefined observables, in particular CLFV observables. The second part of the paper explains how to define new observables such that their automatic computation in any applicable BSM model becomes possible. A key ingredient is the new NPointFunctions extension which allows to use tree-level and loop calculations in the model-independent setup of observables. Three examples of increasing complexity are fully worked out. This illustrates the features and provides code snippets that may be used as a starting point for implementation of further observables.

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arXiv2023

How robust are particle physics predictions in asymptotic safety?

The framework of trans-Planckian asymptotic safety has been shown to generate phenomenological predictions in the Standard Model and in some of its simple new physics extensions. A heuristic approach is often adopted, which bypasses the functional renormalization group by relying on a parametric description of quantum gravity with universal coefficients that are eventually obtained from low-energy observations. Within this approach a few simplifying approximations are typically introduced, including the computation of matter renormalization group equations at 1~loop, an arbitrary definition of the position of the Planck scale at $10^{19}$ GeV, and an instantaneous decoupling of gravitational interactions below the Planck scale. In this work we systematically investigate, both analytically and numerically, the impact of dropping each of those approximations on the predictions for certain particle physics scenarios. In particular we study two extensions of the Standard Model, the gauged $B-L$ model and the leptoquark $S_3$ model, for which we determine a set of irrelevant gauge and Yukawa couplings. In each model, we present numerical and analytical estimates of the uncertainties associated with the predictions from asymptotic safety.

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arXiv2023

Box enhanced Charged Lepton Flavor Violation in the Grimus-Neufeld model

In the Grimus-Neufeld model (GNM) the neutrino mass generation from an extended Higgs sector leads to bounds from Charged Lepton Flavour Violating (cLFV) processes. Here we update bounds from the previous study by extending the parameter space to nonvanishing Majorana phase of the Pontecorvo-Maki-Nakagawa-Sakata matrix and to heavier charged Higgs boson masses. Three-body cLFV decays are shown to contribute significantly in large mass regions, as the boxes are enhanced relatively to photonic diagrams. This is in contrast to the smaller mass region studied before, in which the two-body decays tightly restrict the parameter space. The Majorana phase is shown to change limits within one order of magnitude. The tiny seesaw scale is assumed, which makes the cLFV decays of the GNM to be similar to the scotogenic model and the scoto-seesaw models.

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arXiv2023

Constraints on $Z'$ solutions to the flavor anomalies with trans-Planckian asymptotic safety

Motivated by the flavor anomalies in $b \to s$ transitions, we embed minimal models with a $Z'$ gauge boson, vector-like fermions, and a singlet scalar in the framework of trans-Planckian asymptotic safety. The presence of a fixed point in the renormalization group flow of the models' parameters leads to predictions for the $γ/Z'$ kinetic mixing, the New Physics Yukawa couplings, and the quartic couplings of the scalar potential. We derive the constraint on the kinetic mixing from the most recent high-mass dilepton resonance searches at the LHC, showing that this bound is often inescapable in this framework, unless the U(1) charges conspire to forbid the radiative generation of kinetic mixing. In the latter case, the parameter space consistent with the flavor anomalies can still be probed in depth by direct LHC searches for heavy vector-like quarks and leptons. We derive the current exclusion bounds and projections for future high-luminosity runs.

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arXiv2022

Charged lepton flavor violating processes in the Grimus-Neufeld model

Charged Lepton Flavour Violating (cLFV) decays constrain the relationship between the neutrino and the scalar sectors of the Grimus-Neufeld model (GNM), an appealing minimal model of neutrino masses. It turns out, that in the scenario, where the seesaw scale is lower than the electroweak one, cLFV is completely defined by the new Yukawa interactions between the additional single heavy Majorana neutrino, the second Higgs doublet and the lepton doublets. Therefore, we derive a useful parameterization for the Yukawa couplings which reproduces by construction the correct PMNS matrix and the correct neutrino masses for both Normal and Inverted ordering at one-loop level. We embed this scenario in the $\texttt{FlexibleSUSY}$ spectrum-generator generator to perform parameter scans. Focusing on the tiny seesaw scale, we show that current $μ\to eγ$ limits provide significant constraints on the scalar sector, and we evaluate the impact of future cLFV $τ$-decay searches for the cases of discovery or non-discovery. The tiny seesaw scale makes the neutrino sector and the cLFV processes in the GNM similar to the scotogenic and the scoto-seesaw models, so we provide constraints for these models as well.

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arXiv2022

FlexibleDecay: An automated calculator of scalar decay widths

We present FlexibleDecay, a tool to calculate decays of scalars in a broad class of BSM models. The tool aims for high precision particularly in the case of Higgs boson decays. In the case of scalar and pseudoscalar Higgs boson decays the known higher order SM QED, QCD and EW effects are taken into account where possible. The program works in a modified $\bar{\text{MS}}$ scheme that exhibits a decoupling property with respect to heavy BSM physics, with BSM parameters themselves treated in the $\bar{\text{MS}}/\bar{\text{DR}}$-scheme allowing for an easy connection to high scale tests for, e.g., perturbativity and vacuum stability, and the many observable calculations readily available in $\bar{\text{MS}}/\bar{\text{DR}}$ programs. Pure BSM effects are taken into account at the leading order, including all one-loop contributions to loop-induced processes. The program is implemented as an extension to FlexibleSUSY, which determines the mass spectrum for arbitrary BSM models, and does not require any extra configuration from the user. We compare our predictions for Higgs decays in the SM, singlet extended SM, type II THDM, CMSSM and MRSSM, as well as for squark decays in the CMSSM against a selection of publicly available tools. The numerical differences between our and other programs are explained. The release of FlexibleDecay officially deprecates the old effective couplings routines in FlexibleSUSY.

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arXiv2022

Precise calculation of the W boson pole mass beyond the Standard Model with FlexibleSUSY

We present an updated calculation of the W boson pole mass in models beyond the Standard Model with FlexibleSUSY. The calculation has a decoupling behaviour and allows for a precise W pole mass prediction up to large new physics scales. We apply the calculation to several Standard Model extensions, including the MRSSM where we show that it can be compatible with large corrections to the W boson mass that would be needed to fit the recent 2022 CDF measurement.

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arXiv2022

NPointFunctions: a calculator of amplitudes and observables in FlexibleSUSY

We present $\texttt{NPointFunctions}$, a package to incorporate desired amplitudes and observables for an arbitrary BSM model in $\texttt{FlexibleSUSY}$. The package relies on the $\texttt{SARAH}$-generated output used with $\texttt{FeynArts}/\texttt{FormCalc}$, embedded in an appropriate way, thus allowing calculations up to one-loop level. The resulting tool is an extension to $\texttt{FlexibleSUSY}$, a generator of spectrum generator programs. $\texttt{NPointFunctions}$ was designed to be customizable, modular and extensible with additional process- or amplitude- dependent contributions. We explain, how these goals are achieved, and discuss modifications to the default $\texttt{FlexibleSUSY}$ workflow.

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arXiv2022

New approach to DM searches with mono-photon signature

High energy e$^+$e$^-$ colliders offer unique possibility for the most general dark matter search based on the mono-photon signature. Analysis of the energy spectrum and angular distributions of photons from the initial state radiation can be used to search for hard processes with invisible final state production. Most studies in the past focused on scenarios assuming heavy mediator exchange. We notice however, that scenarios with light mediator exchange are still not excluded by existing experimental data, if the mediator coupling to Standard Model particles is very small. We proposed a novel approach, where the experimental sensitivity to light mediator production is defined in terms of both the mediator mass and mediator width. This approach is more model independent than the approach assuming given mediator coupling values to SM and DM particles. Summarised in this contribution are published results of our studies concerning simulation of mono-photon events with WHIZARD and the expected sensitivity of the International Linear Collider (ILC) and Compact Linear Collider (CLIC) experiments to dark matter production.

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arXiv2021

Sensitivity of future linear $e^+e^-$ colliders to processes of dark matter production with light mediator exchange

As any $e^+e^-$ scattering process can be accompanied by a hard photon emission from the initial state radiation, the analysis of the energy spectrum and angular distributions of those photons can be used to search for hard processes with an invisible final state. Thus high energy $e^+e^-$ colliders offer a unique possibility for the most general search of dark matter (DM) based on the mono-photon signature. We consider production of DM particles at the International Linear Collider (ILC) and Compact Linear Collider (CLIC) experiments via a light mediator exchange. Detector effects are taken into account within the DELPHES fast simulation framework. Limits on the light DM production in a simplified model are set as a function of the mediator mass and width based on the expected two-dimensional distributions of the reconstructed mono-photon events. The experimental sensitivity is extracted in terms of the DM production cross section. Limits on the mediator couplings are then presented for a wide range of mediator masses and widths. For light mediators, for masses up to the centre-of-mass energy of the collider, coupling limits derived from the mono-photon analysis are more stringent than those expected from direct resonance searches in decay channels to SM particles.

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arXiv2021

Simple BSM explanations of $a_μ$ in light of the FNAL muon $g-2$ measurement

Now that the Fermilab muon $g-2$ experiment has released the results of its Run-1 data, which agrees with the results of the Brookhaven experiment, one can examine the potential of simple extensions to explain the combined $4.2σ$ discrepancy between the SM prediction and experiment. This proceeding examines a single-, two-, and three-field extension of the standard model and examines their ability to explain the muon $g-2$ anomaly, and where possible, produce a dark matter candidate particle with the observed relic density. This is based on work carried out for Ref. [1]. It is found that one can only explain the $a_μ$ discrepancy whilst avoiding dark matter and collider constraints when the contributions from BSM fields benefit from a chirality flip enhancement. However, in general without small couplings and/or large masses, these models can be heavily constrained by collider and dark matter experiments.

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