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M. Berggren

Publications and source records attributed to M. Berggren.

At least 19 recordsLinked to original sources
arXiv2025

ECFA Higgs, electroweak, and top Factory Study

The ECFA Higgs, electroweak, and top Factory Study ran between 2021 and 2025 as a broad effort across the experimental and theoretical particle physics communities, bringing together participants from many different proposed future collider projects. Activities across three main working groups advanced the joint development of tools and analysis techniques, fostered new considerations of detector design and optimisation, and led to a new set of studies resulting in improved projected sensitivities across a wide physics programme. This report demonstrates the significant expansion in the state-of-the-art understanding of the physics potential of future e+e- Higgs, electroweak, and top factories, and has been submitted as input to the 2025 European Strategy for Particle Physics Update.

hep-ex↗
arXiv2025

The Linear Collider Facility (LCF) at CERN

In this paper we outline a proposal for a Linear Collider Facility as the next flagship project for CERN. It offers the opportunity for a timely, cost-effective and staged construction of a new collider that will be able to comprehensively map the Higgs boson's properties, including the Higgs field potential, thanks to a large span in centre-of-mass energies and polarised beams. A comprehensive programme to study the Higgs boson and its closest relatives with high precision requires data at centre-of-mass energies from the Z pole to at least 1 TeV. It should include measurements of the Higgs boson in both major production mechanisms, ee -> ZH and ee -> vvH, precision measurements of gauge boson interactions as well as of the W boson, Higgs boson and top-quark masses, measurement of the top-quark Yukawa coupling through ee ->ttH, measurement of the Higgs boson self-coupling through HH production, and precision measurements of the electroweak couplings of the top quark. In addition, ee collisions offer discovery potential for new particles complementary to HL-LHC.

hep-ex↗
arXiv2025

The ILD Detector: A Versatile Detector for an Electron-Positron Collider at Energies up to 1 TeV

The International Large Detector, ILD, is a detector concept for an experiment at a future high energy lepton collider. The detector has been optimised for precision physics in a range of energies from 90~GeV to about 1~TeV. ILD features a high precision, large volume combined silicon and gaseous tracking system, together with a high granularity calorimeter, all inside a central solenoidal magnetic field. The paradigm of particle flow has been the guiding principle of the design of ILD. ILD is based mostly on technologies which have been demonstrated by extensive research and test programs. The ILD concept is proposed both for linear and circular lepton collider, be it at CERN or elsewhere. The concept has been developed by a group of nearly 60 institutes from around the world, and offers a well developed and powerful environment for science and technology studies at lepton colliders. In this document, the required performance of the detector, the proposed implementation and the readiness of the different technologies needed for the implementation are discussed.

hep-ex↗
arXiv2025

Updated baseline design for HALHF: the hybrid, asymmetric, linear Higgs factory

Particle physicists aim to construct a electron-positron Higgs factory as the next major particle collider. However, the high associated costs motivate the development of more affordable collider designs. Plasma-wakefield acceleration is a promising technology to this end. HALHF is a proposal for a Higgs factory that utilizes beam-driven plasma-wakefield acceleration to accelerate electrons to high energy with high gradient, while using radio-frequency acceleration to accelerate positrons to a lower energy. This asymmetry sidesteps a major difficulty in plasma acceleration: that of accelerating positrons with high efficiency and quality. Since publication, several challenges were identified in the original baseline design. We summarize the updated baseline design, which addresses these challenges, and describe the parameter- and cost-optimization process used to arrive at this design.

physics.acc-ph↗
arXiv2025

A Linear Collider Vision for the Future of Particle Physics

In this paper we review the physics opportunities at linear $e^+e^-$ colliders with a special focus on high centre-of-mass energies and beam polarisation, take a fresh look at the various accelerator technologies available or under development and, for the first time, discuss how a facility first equipped with a technology mature today could be upgraded with technologies of tomorrow to reach much higher energies and/or luminosities. In addition, we will discuss detectors and alternative collider modes, as well as opportunities for beyond-collider experiments and R\&D facilities as part of a linear collider facility (LCF). The material of this paper will support all plans for $e^+e^-$ linear colliders and additional opportunities they offer, independently of technology choice or proposed site, as well as R\&D for advanced accelerator technologies. This joint perspective on the physics goals, early technologies and upgrade strategies has been developed by the LCVision team based on an initial discussion at LCWS2024 in Tokyo and a follow-up at the LCVision Community Event at CERN in January 2025. It heavily builds on decades of achievements of the global linear collider community, in particular in the context of CLIC and ILC.

hep-ex↗
arXiv2024

Synergistic Effect of Multi-Walled Carbon Nanotubes and Ladder-Type Conjugated Polymers on the Performance of N-Type Organic Electrochemical Transistors

Organic electrochemical transistors (OECTs) have the potential to revolutionize the field of organic bioelectronics. To date, most of the reported OECTs include p-type (semi-)conducting polymers as the channel material, while n-type OECTs are yet at an early stage of development, with the best performing electron-transporting materials still suffering from low transconductance, low electron mobility, and slow response time. Here, the high electrical conductivity of multi-walled carbon nanotubes (MWCNTs) and the large volumetric capacitance of the ladder-type π-conjugated redox polymer poly(benzimidazobenzophenanthroline) (BBL) are leveraged to develop n-type OECTs with record-high performance. It is demonstrated that the use of MWCNTs enhances the electron mobility by more than one order of magnitude, yielding fast transistor transient response (down to 15 ms) and high uC* (electron mobility x volumetric capacitance) of about 1 F/cmVs. This enables the development of complementary inverters with a voltage gain of > 16 and a large worst-case noise margin at a supply voltage of < 0.6 V, while consuming less than 1 uW of power.

physics.app-ph↗
arXiv2024

Rational Materials Design for In Operando Electropolymerization of Evolvable Organic Electrochemical Transistors

Organic electrochemical transistors formed by in operando electropolymerization of the semiconducting channel are increasingly becoming recognized as a simple and effective implementation of synapses in neuromorphic hardware. However, very few studies have reported the requirements that must be met to ensure that the polymer spreads along the substrate to form a functional conducting channel. The nature of the interface between the substrate and various monomer precursors of conducting polymers through molecular dynamics simulations is investigated, showing that monomer adsorption to the substrate produces an increase in the effective monomer concentration at the surface. By evaluating combinatorial couples of monomers baring various sidechains with differently functionalized substrates, it is shown that the interactions between the substrate and the monomer precursor control the lateral growth of a polymer film along an inert substrate. This effect has implications for fabricating synaptic systems on inexpensive, flexible substrates.

physics.app-ph↗
arXiv2024

Organic electrochemical neurons and synapses with ion mediated spiking

Future brain-machine interfaces, prosthetics, and intelligent soft robotics will require integrating artificial neuromorphic devices with biological systems. Due to their poor biocompatibility, circuit complexity, low energy efficiency, and operating principles fundamentally different from the ion signal modulation of biology, traditional Silicon-based neuromorphic implementations have limited bio-integration potential. Here, we report the first organic electrochemical neurons (OECNs) with ion-modulated spiking, based on allprinted complementary organic electrochemical transistors. We demonstrate facile biointegration of OECNs with Venus Flytrap (Dionaea muscipula) to induce lobe closure upon input stimuli. The OECNs can also be integrated with all-printed organic electrochemical synapses (OECSs), exhibiting short-term plasticity with paired-pulse facilitation and longterm plasticity with retention >1000 s, facilitating Hebbian learning. These soft and flexible OECNs operate below 0.6 V and respond to multiple stimuli, defining a new vista for localized artificial neuronal systems possible to integrate with bio-signaling systems of plants, invertebrates, and vertebrates.

physics.med-ph↗
arXiv2022

Stau searches and measurements with the ILD concept at the International Linear Collider

One of the most interesting channels to search for SUSY is the direct pair-production of the $τ$-lepton superpartner, $\widetildeτ$. The $\widetildeτ$ is with high probability the lightest of the scalar leptons, so one of the first SUSY particles that can be observerd, and the signature of $\widetildeτ$ pair production signal events is one of the most difficult ones, yielding to the ``worst'' and so most global scenario for the searches. Analysis performed at LEP set the current model-independent $\widetildeτ$ limits, suffering from the low energy of this facility. Only under strong model assumptions, these limits are extended to higher masses by LHC studies. In this contribution we show the capability of the ILC, a future electron-positron collider with energy up to 1 TeV, for determining $\widetildeτ$ exclusion/discovery limits in a model-independent way, including an overview of the current state-of-the-art. The determination of the ``worst'' scenario for $\widetildeτ$ exclusion/discovery, taking into account the effect of the $\widetildeτ$ mixing on $\widetildeτ$ production cross-section and efficiency, is also presented. For selected benchmarks, the prospect for measuring masses and polarised cross-sections will be shown. The studies were done studying events passed through the full detector simulation and reconstruction procedures of the International Large Detector (ILD) concept at the ILC. The simulation included all SM backgrounds, as well as the machine induced ones.

hep-ph↗
arXiv2022

Evaluating the ILC SUSY reach in the most challenging scenario: $\widetildeτ$ NLSP, low $ΔM$ , lowest cross-section

Pair-production of the superpartner of the $τ$-lepton, the $\tildeτ$, is one of the most interesting channels to search for SUSY in: The $\tildeτ$ is likely to be the lightest scalar lepton, and the signature of $\tildeτ$ pair production is one of the experimentally most difficult ones, thereby constituting the "worst" possible scenario for SUSY searches. The current model-independent $\tildeτ$ limits comes from analyses performed at LEP but they suffer from the limited energy of this facility. Limits obtained at the LHC do extend to higher masses, but they are only valid under strong assumptions. The International Linear Collider, the ILC, is a future electron-positron collider, to operate initially at an energy of 250 GeV, then to be upgraded to 500 GeV, and possibly to 1 TeV at a later stage. ILC will be a powerful facility for SUSY searches. The capability of the ILC for determining exclusion/discovery limits for the $\tildeτ$ in a model-independent way is shown in this paper. A detailed study of the "worst" scenario for $\tildeτ$ exclusion/discovery, taking into account the effect of the $\tildeτ$ mixing on $\tildeτ$ production cross-section and detection efficiency, is presented. The study also includes an analysis of the effect of the overlay particles in the $\tildeτ$ searches. The conclusion is that both the exclusion and discovery reaches for this "worst" case would extend to only a few GeV below the kinematic limit at the ILC. Also scenarios with the $\tildeτ$ and the Lightest SUSY Particle (the LSP) quite close in mass can be discovered or excluded at most $\tildeτ$ masses. The studies were done using detailed detector simulation of the ILD concept at the ILC. For signal, the fast detector simulation SGV was used, while the full Geant4 based DDSim was used for the standard model backgrounds.

hep-ph↗
arXiv2021

$\widetildeτ$ searches at the ILC

The direct pair-production of the superpartner of the $τ$-lepton, the $\widetildeτ$, is one of the most interesting channels to search for SUSY in. First of all, the $\widetildeτ$ is likely to be the lightest of the scalar leptons. Secondly the signature of $\widetildeτ$ pair production signal events is one of the experimentally most difficult ones, thereby constituting the "worst" possible scenario for SUSY searches. The current model-independent $\widetildeτ$ limits comes from analyses performed at LEP but they suffer from the limited energy of this facility. Limits obtained at the LHC do extend to higher masses, but they are only valid under strong assumptions. ILC, a future electron-positron collider with energy up to 500 GeV and upgrade capability\footnote{The initial ILC energy is planned to be 250 GeV.}, is a promising facility for SUSY searches. The capability of the ILC for determining exclusion/discovery limits for the $\widetildeτ$ in a model-independent way is shown in this paper, together with an overview of the current state-of-the-art. Results of the last studies of $\widetildeτ$ pair-production at the ILC are presented, showing the improvements with respect to previous results.

hep-ph↗
arXiv2015

Non-Simplified SUSY: Stau-Coannihilation at LHC and ILC

If new phenomena beyond the Standard Model will be discovered at the LHC, the properties of the new particles could be determined with data from the High-Luminosity LHC and from a future linear collider like the ILC. We discuss the possible interplay between measurements at the two accelerators in a concrete example, namely a full SUSY model which features a small stau_1-LSP mass difference. Various channels have been studied using the Snowmass 2013 combined LHC detector implementation in the Delphes simulation package, as well as simulations of the ILD detector concept from the Technical Design Report. We investigate both the LHC and ILC capabilities for discovery, separation and identification of various parts of the spectrum. While some parts would be discovered at the LHC, there is substantial room for further discoveries at the ILC. We finally highlight examples where the precise knowledge about the lower part of the mass spectrum which could be acquired at the ILC would enable a more in-depth analysis of the LHC data with respect to the heavier states.

hep-ph↗
arXiv2013

Non-Simplified SUSY: stau-Coannihilation at LHC and ILC

Simplified models have become a widely used and important tool to cover the more diverse phenomenology beyond constrained SUSY models. However, they come with a substantial number of caveats themselves, and great care needs to be taken when drawing conclusions from limits based on the simplified approach. To illustrate this issue with a concrete example, we examine the applicability of simplified model results to a series of full SUSY model points which all feature a small stau-LSP mass difference, and are compatible with electroweak and flavor precision observables as well as current LHC results. Various channels have been studied using the Snowmass Combined LHC detector implementation in the Delphes simulation package, as well as the Letter of Intent or Technical Design Report simulations of the ILD detector concept at the ILC. We investigated both the LHC and ILC capabilities for discovery, separation and identification of all parts of the spectrum. While parts of the spectrum would be discovered at the LHC, there is substantial room for further discoveries and property determination at the ILC.

hep-ph↗
arXiv2005

Dark Matter with (very) heavy SUSY scalars at ILC

In this paper, six SUSY scenarios with heavy sfermions, mainly based on theoretical arguments and on experimental indications for new physics, are defined. These scenarios, consistent with the amount of dark matter (DM) measured by WMAP, are then analysed in detail providing pertinent examples of the potential of ILC. It is shown that in most cases ILC, with its high precision based on the chargino analysis and in spite of an incomplete coverage of the gaugino and slepton mass spectrum, can predict the amount of DM in our universe with an accuracy which matches the WMAP results.

hep-ph↗
arXiv2004

Experimental Implications for a Linear Collider of the SUSY Dark Matter Scenario

This paper presents the detection issues for the lightest slepton \tildeτ_1 at a future e^+e^- TeV collider given the dark matter constraints set on the SUSY mass spectrum by the WMAP results. It intends to illustrate the importance of an optimal detection of energetic electrons in the very forward region for an efficient rejection of the γγbackground. The TESLA parameters have been used in the case of head-on collisions and in the case of a 10, mrad half crossing angle.

hep-ph↗
arXiv1999

A Direct Measurement of tan(beta): e+e- -> bb -> bbA at a Future e+e- Linear Collider

The experimental sensitivity of the reaction e+e- -> bb -> bbA has been studied with a full-statistics background simulation for sqrt(s) = 500 GeV and L = 500 fb-1. The simulation is based on a fast and realistic simulation of a TESLA detector. For the first time this reaction has been analysed for a future linear collider and we show that a signal could be observed. A significant signal over background is achieved by the application of an Iterative Discriminant Analysis (IDA). For a signal production cross section of only 2 fb, which is expected for a Higgs boson mass of 100 GeV and tan(beta) = 50, we achieve 100 signal over 100 background events, and obtain for a tan(beta) measurement: Delta(tan(beta)) / tan(beta) = 0.07. This measurement requires a high-luminosity future collider as proposed in the TESLA project.

hep-ph↗