We will overview the usage of boosted jet taggers within CMS. We will also discuss how their performance is calibrated for usage in analyses. This includes a new Lund Plane reweighting technique that can calibrate the performance of high-prong jets for which there is no standard model equivalent which can be used as a proxy.
Physics measurements in the highly Lorentz-boosted regime are a critical part of the LHC physics program. In the CMS Collaboration, various boosted-jet tagging algorithms, designed to identify hadronic jets originating from the decay of a massive particle to bb̅ or cc̅, have been developed and deployed in a variety of analyses. This talk summarises the performance of these algorithms with...
Jet substructure has been successful in broadening our understanding of fundamental physics and QCD. In this talk, I will introduce a variety of new energy correlator based observables, specifically the two and three point heavy energy correlators, which measure correlations of energy flow at collider experiments on heavy quarks. These observables provide new insights into jet substructure,...
The energy correlators inside jets are measured for the first time at the CMS experiment. AlphaS is determined from the ratio of 3-point and 2-point correlators.
The future Electron-Ion Collider (EIC) will provide the first electron-nucleus collisions for a variety of nuclei species with high luminosity, wide kinematic coverage, and excellent detector resolution, providing new insights into cold nuclear matter effects and transport phenomena. As jets are an accurate proxy of the struck quark that traverses the nucleus, the signature of the nuclear...
Characterising double-Higgs production has been a major part of the LHC physics program in Run 2 and beyond. We discuss new techniques and results in boosted, hadronic final states in CMS, with a focus on wide-radius jet taggers and data-driven multi-jet background estimation, as well as measurements of gluon-gluon- and vector-boson-fusion HH production in the 4 beauty quark final state in...
Accurate and precise calorimeter modeling presents one of the most significant computational bottlenecks in modern high-energy physics simulation chains. For this reason, extensive work has been done to speed up calorimeter simulation and make it more computationally efficient. A highly promising method for achieving this speed-up is generative machine learning (ML) models. However, most...
The BEST Searches for Vector Like Quarks at CMS
Abstract: The Boosted Event Shape Tagger is a multi-class jet tagger optimized for the diverse final states inherent to all-hadronic decays of Vector-Like Quarks. Its architecture is a simple DNN whose discriminating power benefits from physics-driven observables calculated in the lab frame, but also in a series of Lorentz-boosted frames...
State-of-the-art (SoTA) deep learning models have achieved tremendous improvements in jet classification performance while analyzing low-level inputs, but their decision-making processes have become increasingly opaque. We propose an analysis model (AM) that amalgamates several phenomenologically inspired neural networks to address this interpretability issue without compromising...
The LHC has unlocked a previously unexplored energy regime. Dedicated techniques have been developed to reconstruct and identify boosted top quarks. Measurements in boosted top quark production test the Standard Model in a region with a strongly enhanced sensitivity to high-scale new phenomena. In this contribution, several new measurements of the ATLAS experiment are presented of the...
Identifying boosted hadronic decays of W/Z bosons is central to many LHC physics analyses. This poster presents the performance of constituent-based W/Z boson taggers using large-radius boosted jets reconstructed from Unified Flow Objects (UFOs) in simulated collisions at sqrt(s)=13 TeV. Several taggers which consider all the information contained in the kinematics of the jet constituents are...
Fast simulations which can accurately model jet substructure are will be of utmost importance for boosted jet analyses at the HL-LHC. There has been significant development recently in generative models for accelerating LHC simulations, but less explored are methods for validating these simulations. We present a rigorous study on evaluation metrics, and discuss the novel Frechet and kernel...
The FORMOSA detector at the proposed Forward Physics Facility is a scintillator based detector proposed to search for signatures from high momentum millicharged particles produced in the forward region of the LHC. This talk will cover the challenges of operating such a detector in the forward region, impressive potential sensitivity, and plans for a FORMOSA demonstrator to prove the...
We present searches for additional Higgs bosons produced at high momenta with data collected by the CMS experiment. Searches include additional scalar particles at high mass and searches for decays of the 125 GeV Higgs boson into a pair of light scalars.
Searches for new resonances in two-body invariant masses are performed using an unsupervised anomaly detection technique in events produced in $pp$ collisions at a center-of-mass energy of 13 TeV recorded by the ATLAS detector at the LHC. An autoencoder network is trained with 1% randomly selected collision events and anomalous regions are then defined which contain events with high...
Despite the recent proliferation of symmetry-based machine learning methods in jet physics, the preference for smaller symmetry groups and highly custom architectures negatively impacts explainability and generalizability. In this work, we present an update to our own algorithm, which delivers both significant improvements in the top-tagging performance and the capability to perform full...
Discrepancies between real and simulated collider events are a significant source of uncertainty in LHC physics, especially in the context of training machine learning models, where even small differences in input variable distributions can degrade the performance of a simulation-trained model. In this work we present a deep learning implementation of “chained quantile morphing”: a technique...
We study the effectiveness of theoretically-motivated high-level jet observables in the extreme context of jets with a large number of hard sub-jets (up to N=8). Previous studies indicate that high-level observables are powerful, interpretable tools to probe jet substructure for N≤3 hard sub-jets, but that deep neural networks trained on low-level jet constituents match or slightly exceed...
We present a class of Neural Networks which extends the notion of Energy Flow Networks (EFNs) to higher-order particle correlations. The structure of these networks is inspired by the Energy-Energy Correlators of QFT, which are particularly robust against non-perturbative corrections. By studying the response of our models to the presence and absence of non-perturbative hadronization, we can...
In this talk, we present a new proposal on how to measure quark/gluon jet properties at the Large Hadron Collider (LHC). The main advantage of this approach is that our construction of an observable allows a single set of experimental cuts to be used to select jets, keeping all detector parameters unchanged, and in this way, reducing many systematic uncertainties. We will discuss the details...
After a hard scattering event, an outgoing parton will radiate gluons which fragment into final-state hadrons. To study the radiation patterns of light and heavy partons, we look at the Lund jet plane (LJP), an observable where various types of emissions such as soft-collinear, hard-collinear, and non-perturbative emissions as well as initial-state radiation and the underlying event can be...
Jets are collimated sprays of final-state particles produced from initial high-momentum-transfer partonic scatterings in particle collisions. Since jets are multi-scale objects that connect asymptotically free partons to confined hadrons, jet substructure measurements can provide insight into the parton evolution and the ensuing hadronization processes. Compared to the jets at the LHC, jets...
Modern machine learning (ML) techniques allow us to rethink how the the high dimensional features of jets can be optimally used to probe the strong interaction. Recently a new class of jet substructure observables, the energy correlators (EECs), have been introduced to study the statistical properties inside jets and enable first principle ways to do physics in the complicated LHC environment....
Jet substructure observables are incisive probes of quantum chromodynamics (QCD), providing insight into perturbative and non-perturbative processes, and probing the structure and dynamics of the quark-gluon plasma (QGP). The jet shower is sensitive to multiple scales during its evolution, encoding the physics into correlated angular and momentum space phenomena which cannot be fully...
Jets are powerful probes used to improve our understanding of the strong force.
A useful way of understanding the radiation pattern of the jet is via the Lund jet plane, a representation of the phase space constructed using iterative Cambridge/Aachen declustering. In this talk, we discuss recent jet substructure measurements in pp and PbPb collisions based on Cambridge/Aachen declustering.
With the newly upgraded sPHENIX detector capable of performing high precision jet substructure measurements, we present a comprehensive and systematic jet substructure study at Relativistic Heavy Ion Collider. The study includes a variety of key jet substructure variables such as jet angularities with and without soft-drop or collinear-drop grooming, as well as recoil-free di-jet and...
The properties of partonic fragmentation in QCD depend on the flavors of the partons involved in the 1→2 splitting processes that drive parton showers. These dependencies arise from the differences in the Casimir factors of quarks and gluons, as well as the mass of heavy quarks. To explore these flavor dependencies, we use heavy-flavor jets as an experimental tool, particularly at low and...
Due to its large mass the top quark plays an important role in consistency checks of the Standard Model and new-physics searches. Studies concerning precise theoretical predictions of the top production and its decay are commonly based on the narrow-width (NW) limit of the top quark propagator or on full off-shell computations. The NW limit, where the top quark is treated as an on-shell...
We provide a quantitative interpretation for direct top quark mass measurements in terms of a field-theoretic mass scheme. A relation between the top quark mass parameter in Monte Carlo generators and the MSR mass at a scale of R = 3 GeV is derived. This is achieved by fitting Monte Carlo templates for the simulated jet mass distribution of large-radius jets containing a hadronically-decaying...
Several jet flavor identification strategies have been employed to identify jets originating from heavy-flavor quarks and from the decay of heavy Lorentz-boosted objects. Often, separate tagging strategies are utilized for different Lorentz-boost regimes of the target physics object. For instance, in searches for the Higgs boson decaying into a pair of heavy-flavor quarks, a division is made...
We describe a new jet clustering algorithm named SIFT (Scale-Invariant Filtered Tree) that maintains the resolution of substructure for collimated decay products at large boosts. The scale-invariant measure combines properties of kT and anti-kT by preferring early association of soft radiation with a resilient hard axis, while avoiding the specification of a fixed cone size. Integrated...
Jets are the most familiar and complex physical objects in high-energy physics experiments.
Since jets invariably appear in critical elementary particle processes, identifying their origin has become an essential technique for physical analysis, including new particle searches and precision measurements.
Many particles are produced in jets, detected by particle detectors, and reconstructed...
The pursuit of detecting high-energy Higgs boson decays into a pair of heavy quarks is a prominent focus within the ATLAS experiment's physics program. In this study, we introduce an innovative tagger that leverages graph networks and employs tracks as input constituents. Our approach demonstrates a substantial improvement when compared to the previous boosted Higgs boson tagger employed by...
Accurate and precise calorimeter modeling presents one of the most significant computational bottlenecks in modern high-energy physics simulation chains. For this reason, extensive work has been done to speed up calorimeter simulation and make it more computationally efficient. A highly promising method for achieving this speed-up is generative machine learning (ML) models. However, most...
The properties of partonic fragmentation in QCD depend on the flavors of the partons involved in the 1→2 splitting processes that drive parton showers. These dependencies arise from the differences in the Casimir factors of quarks and gluons, as well as the mass of heavy quarks. To explore these flavor dependencies, we use heavy-flavor jets as an experimental tool, particularly at low and...
The future Electron-Ion Collider (EIC) will provide the first electron-nucleus collisions for a variety of nuclei species with high luminosity, wide kinematic coverage, and excellent detector resolution, providing new insights into cold nuclear matter effects and transport phenomena. As jets are an accurate proxy of the struck quark that traverses the nucleus, the signature of the nuclear...
We provide a quantitative interpretation for direct top quark mass measurements in terms of a field-theoretic mass scheme. A relation between the top quark mass parameter in Monte Carlo generators and the MSR mass at a scale of R = 3 GeV is derived. This is achieved by fitting Monte Carlo templates for the simulated jet mass distribution of large-radius jets containing a hadronically-decaying...
We describe a new jet clustering algorithm named SIFT (Scale-Invariant Filtered Tree) that maintains the resolution of substructure for collimated decay products at large boosts. The scale-invariant measure combines properties of kT and anti-kT by preferring early association of soft radiation with a resilient hard axis, while avoiding the specification of a fixed cone size. Integrated...
Event shape observables provide incisive probes of QCD, both its perturbative and nonperturbative aspects. Grooming techniques have been developed to separate perturbative from non-perturbative components of jets in a theoretically well-controlled way, and have been applied extensively to jet measurements in hadronic collisions.
In this contribution, the first application of grooming...
In this talk, we present a new proposal on how to measure quark/gluon jet properties at the Large Hadron Collider (LHC). The main advantage of this approach is that our construction of an observable allows a single set of experimental cuts to be used to select jets, keeping all detector parameters unchanged, and in this way, reducing many systematic uncertainties. We will discuss the details...
Jet substructure observables are incisive probes of quantum chromodynamics (QCD), providing insight into perturbative and non-perturbative processes, and probing the structure and dynamics of the quark-gluon plasma (QGP). The jet shower is sensitive to multiple scales during its evolution, encoding the physics into correlated angular and momentum space phenomena which cannot be fully...
Despite the recent proliferation of symmetry-based machine learning methods in jet physics, the preference for smaller symmetry groups and highly custom architectures negatively impacts explainability and generalizability. In this work, we present an update to our own algorithm, which delivers both significant improvements in the top-tagging performance and the capability to perform full...
We study the effectiveness of theoretically-motivated high-level jet observables in the extreme context of jets with a large number of hard sub-jets (up to N=8). Previous studies indicate that high-level observables are powerful, interpretable tools to probe jet substructure for N≤3 hard sub-jets, but that deep neural networks trained on low-level jet constituents match or slightly exceed...
Jets are the most familiar and complex physical objects in high-energy physics experiments.
Since jets invariably appear in critical elementary particle processes, identifying their origin has become an essential technique for physical analysis, including new particle searches and precision measurements.
Many particles are produced in jets, detected by particle detectors, and reconstructed...
The LHC has unlocked a previously unexplored energy regime. Dedicated techniques have been developed to reconstruct and identify boosted top quarks. Measurements in boosted top quark production test the Standard Model in a region with a strongly enhanced sensitivity to high-scale new phenomena. In this contribution, several new measurements of the ATLAS experiment are presented of the...
The FORMOSA detector at the proposed Forward Physics Facility is a scintillator based detector proposed to search for signatures from high momentum millicharged particles produced in the forward region of the LHC. This talk will cover the challenges of operating such a detector in the forward region, impressive potential sensitivity, and plans for a FORMOSA demonstrator to prove the...
