In supersymmetric theories the Higgs boson masses are derived
quantities where higher-order corrections have to be included in order
to match the measured Higgs mass value at the precision of current
experiments. Closely related through the
Higgs potential are the Higgs self-interactions. In addition, the measurement of
the trilinear Higgs self-coupling provides the first step towards...
The Rebalance and Smear technique for the modeling of QCD backgrounds to searches for dark matter at the LHC is presented as a publicly available toolkit. Bayesian inference is carried out on real data events to estimate a latent space of the true jet energy values within each event. The latent space is sampled multiple times per event according to a known PDF of the detector response to the...
We present a measurement of the signal strength of the Higgs boson decaying to a pair of bottom quarks and produced via Vector Boson Fusion (VBF). The study is performed using 91/fb of pp collision data collected by the CMS experiment at a centre-of-mass energy of 13 TeV. The measurement is performed for events with at least four energetic jets: two b-jets originating from the Higgs boson...
We present preliminary results of the measurement and QCD analysis of double-differential inclusive jet cross sections in proton-proton collisions by using the full Run II data collected by CMS experiment at LHC at a center of mass energy of 13 TeV. The higher accumulated luminosity of full Run II opens up new corners of the phase space. This permits further testing of the Standard Model (SM)...
The trilinear coupling of the 125-GeV Higgs boson, $\lambda_{hhh}$, is crucial quantity to study in the future. It controls the shape of the Higgs potential, away from the electroweak (EW) vacuum, and determines the strength of the EW phase transition. It can also deviate significantly from its SM prediction, even in scenarios where New Physics is hidden from direct observation (e.g. scenarios...
The electroweak mixing angle is a fundamental parameter of the theory of electroweak interactions. Its value has been measured precisely at the $\mathrm{Z}$-pole at colliders. In this contribution, we propose to exploit measurements of Neutral-Current Drell-Yan production at the Large Hadron Collider at large invariant dilepton masses to determine the energy scale dependence (running) of the...
The search for Higgs boson production in association with a top quark pair (ttH) has been performed in the H to bb decay channel at the LHC. These searches are limited by the modelling uncertainties of the main background: ttbb. The aim is to compare the modelling of important backgrounds to ttH measurements in the ttH(H->bb) decay channel and the treatment of the associated theory...
At the CMS experiment, a two-layer trigger system is used to decide which collision events to store for later analysis. Due to the large number of low energy collisions at the LHC, currently used triggers often rely on momentum thresholds, only triggering on events with at least one highly energetic object. In searches for certain signatures, this leads to potentially relevant events being...
The greatest achievement of the LHC is the discovery of the Higgs boson in 2012. Testing the properties of this newly discovered particle represents a crucial task in the understanding of the fundamental laws of nature. Very important is to study how the Higgs boson couples to another exotic particle, the top quark. This can be done studying the process where the Higgs boson is produced in...
Reinterpreting the LHC results as bounds on the Wilson Coefficients (WCs) of the Standard Model Effective Field Theory (SMEFT) allows studying new-physics effects in a model-independent way with minimal assumptions. However, the large number of effective interactions along with theoretical and experimental uncertainties result in poor constraints on WCs that motivate the use of alternative...
The top-quark pair production in association with a $W$ boson is an important background to processes like $t\bar{t}H$ or 4-tops production. Due to higher order electroweak corrections, the process is difficult to model. In consequence, a mismodelling of $t\bar{t}W$ surpassing 2$\sigma$ has been observed in previous analyses. Thus, it is of high importance to increase our understanding of...
The measurement is performed on highly boosted top quark pair events resulting in non isolated leptons and overlapping jets. Jet substructure variables are used to identify the boosted top quark and the W boson. The top quark charge asymmetry is measured for events with ttbar invariant mass larger than 750 GeV. The measurement is found to be in good agreement with the standard model prediction...
The first measurement of the top quark pair production cross section in proton-proton collisions at $\sqrt{s} = 13.6 \, \mathrm{TeV}$ is presented. A novel measurement technique, based on a likelihood fit to events with one or two charged leptons, is used to analyze data recorded with the CMS detector at the CERN LHC corresponding to an integrated luminosity of $1.20 \, \mathrm{fb}^{-1}$. The...
The production of four top quarks is an extremely rare process which has not been observed yet. Also, its high sensitivity to the top Yukawa coupling and some beyond the standard model signatures make it a very interesting process to study. The decay channel where two of the top quarks decay into same sign leptons have a very low level of background contamination. One of the dominant...
At the CMS experiment, a growing reliance on the fast Monte Carlo application (FastSim) will accompany the high luminosity and detector granularity expected in Phase 2. The FastSim chain is roughly 10 times faster than the application based on the GEANT4 detector simulation and full reconstruction referred to as FullSim. However, this advantage comes at the price of decreased accuracy in some...
In particle physics, precise simulations are necessary to enable scientific progress. However, accurate simulations of the interaction processes in calorimeters are complex and computationally very expensive, demanding a large fraction of the available computing resources in particle physics at present. Various generative models have been proposed to reduce this computational cost. Usually,...
The top quark being the heaviest fundamental particle in the Standard Model (SM) plays a very important role in the study of fundamental interactions. It has a very short lifetime and it decays before it hadronizes, passing its properties to its decay products. Top quark pair production in association with a photon ($t\bar{t}\gamma$) is a very important process for measuring the coupling...
Final results of a search for pair-produced scalar and vector leptoquarks (LQs) in single-lepton final states are presented. The LQs are assumed to couple to third-generation quarks and first- or second-generation leptons. Such LQs with flavour-off-diagonal couplings arise for example in theories aiming for explanations of anomalies observed in $b\rightarrow s\ell \ell$ and $b\rightarrow c\ell...
Searches for new physics and their reinterpretations constrain the parameter space of models with exclusion limits in typically only few dimensions.
However, the relevant theory parameter space often extends into higher dimensions. Limited computing resources for signal process simulations impede the coverage of the full parameter space. We present an Active Learning approach to address this...
Flavour-changing neutral currents in the top-quark sector are heavily suppressed in the Standard Model. However, several theories beyond the Standard Model predict significant enhancements for these transitions, motivating searches for them at current and future collider experiments.
In this talk, studies for the sensitivity to a left-handed $tZc$ coupling $g$ are presented. In contrast to...
Various theories predicting an extended Higgs sector predict also the existence of at least one set of charged Higgs bosons.
The main production mode of these new particles depends on their mass. For charged Higgs boson masses larger than the sum of the top and the bottom quark mass, the dominant production mode is expected to be in association with a top quark and a bottom quark...
The strategies for and the performance of the CMS tracker alignment during the ongoing LHC Run 3 data-taking period are described. The data-driven methods used to derive the alignment parameters for data reprocessing and the set of validations that monitor the physics performance after the update of the tracker alignment constants are reviewed.
The optimal way to measure the top-photon coupling and later interpret it within an EFT-framework would be an $e^+e^-$ collider with sufficient energy. As such a collider does not exist, another possibility is to look for $t\bar{t}$ pairs in association with a photon. Unfortunately, most of such photons will originate from the decay products of the top quarks and hence do not convey any...
A search for new particles decaying to top quark pairs is presented. The analysis uses pp-collision data with a center-of-mass energy of 13 TeV, collected with the CMS experiment during Run-2 of the LHC. The data correspond to an integrated luminosity of $138 ~\text{fb}^{-1}$.
The search is performed in final states with one lepton, missing transverse energy and jets, and exploits novel...
Neutrinos are probably the most mysterious particles of the Standard Model. The mass hierarchy and oscillations, as well as the nature of their antiparticles, are currently being studied in experiments around the world. Moreover, in many models of New Physics, baryon asymmetry or dark matter density in the universe are explained by introducing new species of neutrinos. Heavy neutrinos of the...
Dark photons originated from new hidden abelian symmetries are one of the best motivated extensions of the Standard Model. However, the simple
addition of a massive vector in the low energy theory might cause problems at high energies, meaning that there must be other new physics states charged under this new hidden symmetry. One way out is to directly UV complete the model by adding a dark...
There exist strong hints for the existence of physics beyond the standard model (BSM). At the CMS experiment, the first event selection step is the Level 1 (L1) trigger system, which decides whether an event is stored for further analysis. Assuming that BSM events differ from standard model (SM) events, a trigger decision could then utilize this difference to detect anomalous event properties...
We will discuss a novel framework for addressing QCD factorization in the emission of multiple soft or collinear partons. The purpose of this discussion is to allow for a more precise description of hadron collider data and to better handle theoretical uncertainties from parton showers.
We have developed a power counting algorithm in emission amplitudes with the goal of parameterizing the...
Usually, effective field theories (EFTs) for axion-like particles (ALPs) are built assuming a shift symmetry for the ALP due to the global U(1) Peccei-Quinn (PQ) symmetry that is at the heart of the axion mechanism. However, it is generally believed that global symmetries, in particular axion shift symmetries, can only be approximate. Therefore, it is important to include shift-breaking...
In this talk I will go over the study of a new class of SM extensions which can contribute towards the anomalous magnetic moment of the muon with chiral enhancement. We will focus on a particular 3-field extension which explaons g-2 at one-loop but can also account for tree-level solutions of the neutral B-anomalies and the Cabibbo angle anomaly.
