Many physics problems such as neutrino masses and the nature of dark matter predict particles with long lifetimes as an important possibility in the search for new phenomena. When produced at colliders, these long-lived particles (LLPs) have a distinct experimental signature: they can decay far from the collision point, or even completely pass through a detector before decaying. Since most of...
In this work the prospects for measurements of the top-quark couplings at future colliders are presented. Projections are presented for the high luminosity phase of the Large Hadron Collider and a future Higgs/electroweak/top factory electron-positron collider. Results are presented for the expected bounds on Wilson coefficients of the relevant SMEFT operators from a global fit to the...
Current R&D on silicon detectors considered for the IDEA concept is described. In particular recent results from the ARCADIA project and the ATLASpix3 sensors. Additional work on LGADs and vertex detector mechanics will also be described.
The proposed LUXE (LASER Und XFEL Experiment) at DESY, Hamburg, using the 16.5 GeV electron beam from the European XFEL, aims to probe QED in the non-perturbative regime created in collisions between high-intensity laser pulses and high-energy electron or photon beams. This setup also provides a unique opportunity to probe physics beyond the Standard Model by leveraging the large photon flux...
Feebly interacting massive particles (FIMPs) are characterised by very weak couplings and can be mediators to the dark sector or dark matter (DM) candidates themselves. In the latter case, the DM abundance is determined by the freeze-in mechanism (in contrast to freeze-out for WIMPs). Many FIMP scenarios are difficult to be constrained at the LHC and future e+e- Higgs factories seem to be...
Time Projection Chamber (TPC) could be used as a central high spatial resolution tracking detector at future electron-positron colliders such as ILC, CEPC or FCC-ee. A large worldwide community of physicists is working to realize EWK precision physics program at the future e+e- Higgs Factory. In the ILD detector concept, a large volume TPC is embedded in a magnetic field of B=3.5T, the...
The direct pair-production of the tau-lepton superpartner, stau, is one of the most interesting
channels to search for SUSY. First of all the stau is with high probability the lightest of
the scalar leptons. Secondly the signature of stau pair production signal events is one of
the most difficult ones, yielding the 'worst' and thus most general scenario for the searches.
The most...
The drift chamber proposed for the IDEA detector concept and the associated R&D in progress will be described. In particular current work on the cluster counting technique will be reported, including results from recent test beams at CERN.
The muon system for the IDEA detector is discussed. In particular current and future R&D on chambers based on the micro-rWell techique are described,...
A study of the prospects for discovering or excluding SUSY at various
proposed future colliders is presented. The study is based on scan-
ning the relevant parameter space of (weak-scale) SUSY parameters.
In particular, I concentrate on the properties most relevant to evalu-
ate the experimental prospects: mass differences, lifetimes and decay-
modes. The observations are then confronted...
In the CP-violating 2HDM, the CP-violating Higgs to fermions couplings can make an additional loop contribution on the Higgs to gauge bosons couplings. In order to address this aspect, we consider a generic model which has the effective CP-violation structure of the Higgs to gauge bosons couplings. We explore the effect of CP-violation term via the process $e^+ e^- \rightarrow HZ, Z\rightarrow...
One of the important aspects of the future Higgs factory is particle identification, which is important for precision measurements and plays a crucial role for flavour physics. Recent technology developments of Si sensors, e.g. LGADs, enable time resolutions below 50 ps. This allows to use measurement of the time-of-flight as a tool for particle identification of $\pi^{\pm}$, $K^{\pm}$ and $p$...
The Z-pole operation at FCC-ee presents an unprecedented opportunity for heavy flavor physics, as the production of $5×10^{12}$ Z bosons will result in about $8×10^{11}$ b-quark pairs. Among all species of B hadrons produced at FCC-ee, the purely leptonic decays of the $B^+_c$ and $B^+$ mesons are clean experimental probes to measure the off-diagonal CKM elements $|V_cb|$ and $|V_ub|$, and are...
The electroweak (EW) sector of the Minimal Supersymmetric Standard Model (MSSM) can account for a variety of experimental data. The lightest SUSY particle (LSP), the lightest neutralino, is a perfect Dark Matter (DM) candidate. The EW spectrum can easily explain the discrepancy between the experimental value of the anomalous magnetic moment of the muon, $(g-2)_\mu$, and its SM prediction....
Extension of the Two Higgs Doublet model augmented with a complex scalar singlet (2HDMS) is a well motivated candidate for Beyond Standard Model (BSM) Physics. In this talk, we focus on the dark matter (DM) phenomenology of 2HDMS and investigate cases where the singlet doesnot obtain a vacuum expectation value (vev) and act as the DM candidate. We also consider the case where the singlet...
We investigate the prospects for producing new, light, hidden states at a future $e^+e^-$ collider in a Higgsed dark $U(1)_D$ model, (the Double Dark Portal model). The simultaneous presence of both vector and scalar portal couplings immediately modifies the SM $e^+e^-\to Zh$ process at leading order in each coupling. After accounting for current constraints, we demonstrate that a future Higgs...
We analyze the parameter space allowed in the Two Higgs Doublet Model (2HDM) with respect to all current experimental and theoretical constraints. We show the allowed ranges for the various triple Higgs couplings, depending on the Yukawa type of the model. We discuss the accessibility of BSM triple Higgs couplings at the ILC and CLIC.
We discuss the mounting evidence for a 95 GeV Higgs boson, as well as interesting excesses in the searches for heavier Higgs bosons at $\sim$ 400 GeV. We show how these excesses can described in the Two Higgs Doublet Model plus real singlet (N2HDM), or in the Next-to-Minimal Supersymmetric Standard Model (NMSSM). We discuss the physics potential of future $e^+e^-$ colliders to analyze these scenarios.
LHC has discovered a light boson h(125), residual of EWSB in the SM and no heavy particle. More generally, one can assume that scalars due to BSM symmetry breaking mechanisms are likely to be the lightest particles produced at LHC and the only new particles reachable at future lepton colliders. From a systematic survey of LHC data, I conclude that there are 4 likely candidates, all reaching a...
Simulation in High Energy Phyiscs (HEP) places a heavy burden on the available computing resources and is expected to become a major bottleneck for the upcoming high luminosity phase of the LHC and for future Higgs factories, motivating a concerted effort to develop computationally efficient solutions. Methods based on generative machine learning methods hold promise to alleviate the...
LCFIPlus, a combined package for vertex finding, jet clustering and flavor tagging is a software package used as a standard tool for the jet analysis of linear colliders since 2012. As the author is one of the original developers, the overview of the software and performance on the ILD is presented. The recent development in our group, yet not finished, to improve the performance of vertex...
CLIC is a linear e$^+$e$^-$ collider designed to reach center-of-mass energies ranging from 350 GeV, 1.4 TeV up to 3 TeV. Individual measurements of Higgs couplings in various Higgs production and decay channels are subject of a global fit in order to achieve the ultimate statistical precision of the cumulative CLIC data. In this talk we discuss the $\mathrm{\sigma x BR(H \rightarrow ZZ^*)} $...
An important goal at future Higgs factories are precise measurements of the 125
GeV Higgs boson properties. As the Higgs boson predominantly decays
to $b\bar{b}$, the precise reconstruction of heavy flavor jets is crucial. A source
of uncertainty for these jets is missing momentum from semi-leptonic
decays $b\to\ell\nu X$. Recent work has shown the possibility of correcting
this missing...
The particle physics community has concluded that the next collider should be a Higgs factory with the ability to also produce a large number of W and Z bosons. In the ongoing discussions it has become increasingly clear that particle identification including charged hadron ID is a key feature that enables a number of analyses and improves many. A number of different PID systems - from the...
Constrained fits improve the kinematic reconstruction of the final state in many Higgs, top and electroweak physics studies. This is a powerful tool, particularly at $e^{+}e^{-} $ colliders where the initial state four-momentum is known and can be employed to constrain the final state. An accurate estimate of the measurement uncertainties, particularly for composed objects like jets, is a...
The process ee->qq with qq=ss,cc,bb,tt plays a central role in the physics programs of high energy electron-positron colliders operating from the O(100GeV) to O(1TeV) center of mass energies. Furthermore, polarised beams as available at the International Linear Collider (ILC) are an essential input for the complete measurement of the helicity amplitudes that govern the production cross...
Particle identification is a highly desirable attribute of an experiment at a future e+e- collider. For example, high luminosity operation at the Z pole will provide opportunities for precise flavour-physics measurements, for which hadron identification is mandatory. The ability to tag the quark flavour of jets, for instance from Higgs decays, will also be greatly enhanced by high quality...
One of the challenges for future e+e- colliders is adequate control of
the center-of-mass energy, and the associated luminosity spectrum.
For linear colliders at all energies and for circular colliders
at center-of-mass energies above 200 GeV one can not rely on resonant
beam depolarization and must use collision data driven methods.
The contribution will focus on progress related to...
The nature of electroweak symmetry breaking and the Higgs bosons are likely paths to physics beyond the standard model. Neutral naturalness, symmetry based constructions for addressing the electroweak hierarchy problem/puzzle, have garnered increasing interest as LHC bounds on new colored states have increased. These models often predict new electroweak states along with a rich Higgs sector. I...
Investigating the trilinear Higgs coupling $\lambda_{hhh}$ is crucial to determine the structure of the Higgs potential and to probe possible signs of physics beyond the Standard Model (SM). Focusing on the Two-Higgs-Doublet Model as a concrete example, I will discuss the calculation of the dominant two-loop contributions to $\lambda_{hhh}$, and I will show that this coupling can, in certain...
The next generation of collider detectors will make full use of Particle Flow algorithms, requiring full imaging calorimeters. The latter have been developed during the past 15 years by the CALICE collaboration and are now reaching maturity. The state-of-the-art and the remaining challenges will be presented for all investigated readout types. We will describe the commissioning, including beam...
In this talk three-loop QCD corrections to heavy quark form factors
are presented. They constitute the virtual corrections for various
processes as, e.g., top quark production in $e^+ e^-$ annihilation or
Higgs decay into heavy quarks. A semi-numerical method is discussed,
which is based on expansions around singular and regular kinematical
points. They are matched at intermediate values...
Neutrinos are probably the most mysterious particles of the Standard Model. The mass hierarchy, oscillations and the nature of their antiparticles are currently being studied in many experiments. Moreover, in models of New Physics, baryon asymmetry or dark matter density are explained by introducing new species of neutrinos. Among others, heavy neutrinos of the Dirac or Majorana nature were...
The trilinear coupling of the 125-GeV Higgs boson, $\lambda_{hhh}$, is one of the most important quantities to investigate in the future. It controls the shape of the Higgs potential, and in turn it determines the strength of the electroweak phase transition. It can also exhibit large deviations from its SM predicition, even in scenarios where New Physics is hidden from direct observation...
With mono-photon signature, high energy e$^+$e$^-$ colliders offer unique possibility to look for processes with fully invisible final state, pair-production of dark matter particles in particular. Most studies in the past focused on scenarios assuming heavy mediator exchange. However, scenarios with light mediator exchange are still not excluded by existing experimental data, if the mediator...
Jet substructure is an important tool in analyses at the currently running LHC
experiments. These observables, and likewise related event shapes, can be
expected to play an important role at future colliders, both in the study of QCD
effects as well as in the tagging of jet properties to identify signal enhanced
phase space regions in various analyses. In this talk I will present...
Higgs Factories detector will require high precision highly granular ECAL.
The Silicon-Tungsten ECAL is optimised for the particle flow with cell size of 5×5 mm².
We propose here a revisitation of the Silicon-Tungsten ECAL parameters to optimise the energy, timing, position and angle resolutions for given cost (amount of tungsten, number of layers) based on detailed simulations.
Establishing the shape of the Higgs potential is invaluable in paving a path forward for understanding the principles behind the Higgs mechanism. As the Higgs self-couplings are directly related to the Higgs potential, their measurements are crucial to either verify the SM mechanism for electroweak symmetry breaking sector or uncover new physics.
The physics programmes at future $e^+e^-$...
In theories where dark matter is explained by the existence of a 'dark sector', interacting with the visible sector of the standard model via gravitation, the photon of the dark sector, the dark photon $(A_{D})$, might be the only visible manifestation of the dark sector due to kinetic mixing with the (ordinary) photon. The strength of the mixing is given by a mixing parameter $(\epsilon)$....
The status of the current R&D on an optical fiber based Dual Readout calorimeter will be discussed, including results from test beams at DESY and CERN. Plans for the construction of a new prototype with full containment of the hadronic shower will be shown.
A crystal EM calorimeter addition to the IDEA detector is also discussed, including both simulated performance improvements and future...
I will present recent developments on accurate (QCD) parton showers at the NLL level and I will outline new approaches based on amplitude level evolution which have led to improved algorithms, links to hadronization models, and touch further aspects such as electroweak evolution.
New U(1) gauge theories involving Standard Model (SM) fermions typically require additional electroweak fermions for anomaly cancellation. We study the non-decoupling properties of these new fermions, called anomalons, in the Z−Z′−γ vertex function, reviewing the connection between the full model and the effective Wess-Zumino operator. We calculate the exotic Z→Z′γ decay width in U(1)B−L and...
The effective field theory approach to the Standard Model, the SMEFT, has been used to study LHC data with ever increasing theoretical precision and sophistication recently. The explosion in the number of parameters in the SMEFT as a function of operator mass dimension, and the technical challenge or reformulating SM predictions consistently into the SMEFT were very serious problems for years....
Photo-production is a non-negligible contribution to cross-sections at lepton—proton and lepton—lepton colliders, amounting to in fact over half of the QCD cross section. In this talk I will discuss the framework in the Sherpa event generator that allows the calculations of both unresolved and resolved photon contributions. I will show comparisons of simulated events at MC@NLO accuracy with...
The determination of the Higgs self-coupling from di-Higgs events with very high precision is one of the clearest benchmarks for the FCC-hh. Its potential has been well established already in several final states. In this talk studies into final states of the di-Higgs system which involve neutrinos are presented. The benefit of studying yet another di-Higgs final state is two-fold: First, any...
With technically mature design and well understood physics program, ILC is a realistic option for realization of a Higgs factory. With a unique physics reach of a linear collider, ILC will significantly complement projections for HL-LHC. Energy staged data collection, employment of beam polarization and capability to reach a TeV center-of-mass energy enable unique precision measurements of...
The Higgs boson trilinear and quartic self-couplings are directly related to the shape of the Higgs potential; measuring them with precision is extremely important, as they provide invaluable information on the electroweak symmetry breaking and the electroweak phase transition.
\In this paper, we perform a detailed analysis of double Higgs boson production, through the gluon-gluon fusion...
The well-known initial state of e+e- colliders can be exploited in physics analyses by fits of the measured quantities to kinematic constraints, called kinematic fitting. Compared to LEP, though, the detector precision increased dramatically, while initial-state radiation and beamstrahlung make the initial-state somewhat less well known, making new developments mandatory. This contribution...
Here we address the results of a full simulation of experimental measurement of the Standard Model Higgs boson decaying to a pair of photons at 3 TeV center-of-mass energy at the Compact Linear Collider (CLIC). Since photons do not couple to Higgs boson at a tree level, any deviation of the Higgs to photons coupling may indicate a New Physics. We show that the product of the Higgs production...
Although the LHC experiments have searched for and excluded many proposed new particles up to masses close to 1 TeV, there are many scenarios that are difficult to address at a hadron collider. This poster gives an overview of recent ILD studies on new particle searches at the ILC. The cases discussed include the light Higgsino, the stau lepton in the coannihilation region relevant to dark...
The aim of the project is to adopt the Pandora framework to build a Neural Network based algorithm that, from a given collection of energy deposits in the dual readout calorimeter, is able to completely reconstruct a jet in the IDEA detector.
Top quarks and in general heavy quarks are likely messengers to new physics. The scrutiny of these particles properties must be completed by the measurement of electroweak qqbar production at high energies, in particular for the top-quark. The International Linear Collider will offer favorable low-background environment of e+e- annihilation combined with a high-energy reach.
This talk will...
The Analogue Hadron Calorimeter (AHCAL) developed by the CALICE collaboration is a scalable technology for a highly granular hadron sampling calorimeter, made from steel absorber plates and 3*3 cm^2 plastic scintillator tiles individually read out by silicon photomultipliers (SiPMs). The tiles are individually wrapped in ESR reflector foil. The SPIROC2E front-end chips are integrated into the...
The FCC-hh is a proposed circular hadron collider at an energy of 100 TeV. The total integrated luminosity is expected to be around 30 $ab^{-1}$. With such a large dataset, 400 times more double-Higgs events are expected than with the full HL-LHC dataset, allowing to measure the Higgs self-coupling with high precision. As a consequence, also rarer final states, which are not within reach of...
The International Large Detector (ILD) is a detector designed primarily for the International Linear Collider (ILC), a high-luminosity linear electron-positron collider with an initial center-of-mass energy of 250 GeV, extendable to 1 TeV. This poster will present the current design of its tracking system; a precision vertex detector positioned very close to the interaction point is followed...
The Semi-Digital Hadron Calorimeter (SDHCAL) is a highly segmented sampling hadronic calorimeter. using large Glass Resistive Plate Chambers (GRPC) as active medium with embedded readout Printed Circuit Board (PCB) hosting 1 cm² copper pads (read independently) on one side and ASIC readout chips (HARDROC) on the other side.
A technological prototype of ~1m3 developed within the CALICE...
Detectors at future e+e- colliders need special calorimeters in the very forward region for a fast estimate of instantaneous and precise measurement of the integrated luminosity. In ILD detector concept, two such calorimeters are foreseen, LumiCal and BeamCal. Both are designed as sandwich calorimeters with very thin sensor planes to keep the Molière radius small, facilitating measurement of...
Here we address the results of a full simulation of experimental measurement of the Standard Model Higgs boson decaying to a pair of photons at 3 TeV center-of-mass energy at the Compact Linear Collider (CLIC). Since photons do not couple to Higgs boson at a tree level, any deviation of the Higgs to photons coupling may indicate a New Physics. We show that the product of the Higgs production...
The determination of the Higgs self-couplings are of primary importance in particle physics and cosmology. Here we will report on our investigation of the measurement of the Standard Model Higgs trilinear self-coupling parameter at the FCC-ee using single Higgs production channels, via its production cross section. We have introduced several Higgs boson production channels at $\sqrt{s} = 240,...
