The high instantaneous luminosity of the LHC leads to multiple proton-proton interactions in the same or nearby bunch crossings (pileup). With the planned increasing instantaneous luminosity in the LHC's future runs, precise identification of individual particles produced from the hard scattering against pileup becomes crucial as this can significantly improve the performance of many physics...
The identification of boosted heavy particles such as top quarks or vector bosons is one of the key problems arising in experimental studies at the Large Hadron Collider. In this talk, we present LundNet, a novel jet tagging method which relies on graph neural networks and an efficient description of the radiation patterns within a jet to optimally disentangle signatures of boosted objects...
The reconstruction and calibration of hadronic final states is an extremely challenging experimental aspect of measurements and searches at the LHC. This talk summarizes the latest results from ATLAS on the calibration of the jet energy and mass scale and resolution of anti-kt R = 0.4 and R = 1.0 jets. Measurements of the calorimeter response to single hadrons will be presented which are the...
For all areas of jet physics, jet corrections, calibration, and reconstruction are essential tools. We present the latest developments explored by the CMS collaboration in jet energy and mass reconstruction and calibration. In addition to traditional techniques, we present novel machine learning methods that boost our physics potential.
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A key application of jet substructure techniques is to disentangle quark- and gluon-initiated jets. One data-driven method to realize the disentangling is jet topics which can give the individual quark and gluon contributions to an observable, but faces challenges associated to finding regions of phase space that can be associated with pure quark and gluon samples. In this talk, I construct...
Jet substructure, defined by observables constructed from the distribution of constituents within a jet, provides the versatility to tailor observables to specific regions of QCD radiation phase space. This flexibility provides exciting new opportunities to study jet quenching in heavy-ion collisions and to
ultimately help reveal the nature of the quark-gluon plasma. The ALICE detector is...
Based on: https://arxiv.org/abs/2106.04589
Abstract:
Grooming techniques, such as soft drop, play a central role in reducing sensitivity of jets to e.g. underlying event and hadronization at current collider experiments. The momentum sharing fraction zg, of the two branches in a jet that pass the soft drop condition, is one of the most important observables characterizing a collinear...
Jets are algorithmic proxies of hard scattered partons, i.e. quarks/gluons, in collisions of high energy particles. Jets derived from clustering algorithms contain information regarding the parton shower, which can be accessed via the SoftDrop algorithm and the Cambridge/Aachen de-clustering. The STAR collaboration has recently measured jet sub-structure observables in pp collisions at...
The soft drop jet mass cross section is as an attractive candidate for precision measurements such as 𝛼𝑠 and top mass, as it can be perturbatively calculable to high accuracy besides being more robust against nonperturbative and underlying event corrections. In this talk I will focus our work on studying prospects of measurement of 𝛼𝑠 at the LHC using state of the art resummed cross section...
Measurements in boosted top quark production test the Standard Model in a previously unexplored regime with a strongly enhanced sensitivity to high-scale new phenomena. Dedicated techniques have been developed to reconstruct and identify boosted top quarks. In this contribution measurements of the ATLAS experiment are presented of the differential cross section and asymmetries in this extreme...
Using the tracking system at the LHC, one can efficiently suppress pile-up contamination and im- prove angular resolution. Observables that only depend on charged particles (tracks) are not in- frared safe in perturbation theory, so any calculation of track-based observables must account for hadronization effects. This can be done by matching the partonic cross section onto perturbative...
LHCb is a spectrometer that covers the forward region of proton-proton collisions, corresponding to the pseudo-rapidity range 2$<\eta<$5. In this unique phase space, LHCb can perform tests of perturbative and non-perturbative QCD models, by studying the production of heavy flavor quarks, like charm and top quarks. In this context the production of a Z boson in association with a c-jet can be...
In this talk, we present measurements of jet energy-energy correlations and jet fragmentation properties using data collected by the ATLAS experiment at √s = 13 TeV. Measurements of transverse energy-energy correlations and their associated azimuthal asymmetries in multi-jet events are compared to next-to-leading-order perturbative QCD calculations and provide a precision test of QCD at large...
We present a phenomenological study of the ungrommed and groomed jet angularities measured in Z+jet production at 13 TeV collision energy. We provide resummed predictions for the angularity distributions at NLO+NLL' accuracy level which are compared to the state-of-the-art NLO Monte Carlo simulations. Our predictions include the effect of soft emissions at large angles, treated as a power...
Jet substructure techniques are increasingly important for LHC searches and measurements alike. QCD multijet final states remain a significant background for these physics analyses but are not well-modeled in Monte Carlo. Jet substructure measurements can probe QCD shower evolution and help improve our understanding and modeling of multijet final states. We present the latest jet substructure...
I present two novel jet observables, based on Lund-declustering, sensitive to the spin-correlations between partons within and between jets respectively (arXiv:2103.16526). I discuss the general structure of these observables for quark and gluon initiated jets at both fixed order and all orders in QCD. For the latter we have extended the MicroJets resummation code and the PanScales showers to...
Droplets of quark-gluon plasma produced in heavy-ion collisions rapidly evolve expanding and cooling. During considerable part of this dynamics, the system can be described within relativistic hydrodynamics. Recently, there were some attempts to include effects of the medium motion to the jet energy loss and jet modification calculations in a variety of models. Here we will present the first...
We re-examine the jet probes of the nucleon spin and flavor structures. We find for the first time that the time-reversal odd (T-odd) component of a jet, conventionally thought to vanish, can survive due to the nonperturbative fragmentation and hadronization effects. This additional contribution of a jet will lead to novel jet phenomena relevant for unlocking the access to several spin...
The planned future Electron Ion Collider (EIC) will provide a unique laboratory for precise studies of both perturbative and non-perturbative QCD through examining the time evolution of jets and their constituents from short to long distances scales. Correlations among identified particle species within jets can reveal tremendous information of this evolution. Utilizing the particle...
N-subjettiness has proven to be a powerful tool for discriminating between boosted signal jets (typically boosted electroweak bosons or top quarks) and light QCD background jets. In this talk I will examine how it can be most effectively used in conjunction with prong finding and grooming algorithms to tag boosted top quarks. I will first examine the performance and effect of hadronisation and...
The ATLAS experiment has extensively explored tagging boosted hadronic objects, especially W/Z bosons and top quarks, using featured-based techniques and machine-learning combinations of features. A variety of tagging algorithms for large-radius jets, reconstructed from unified-flow-objects (UFOs), are presented to identify jets containing the hadronic decay of W/Z bosons and top quarks,...
The use of jet substructure techniques to identify highly boosted top/W/Z/H/b jets has become an important tool for physics searches and measurements at the LHC. We present the latest jet tagging techniques in CMS, including state-of-the-art machine learning methods.
Several extensions of the Standard Model predict new resonances at the TeV scale, which can be expected to couple to gauge and Higgs bosons (W,Z,H,y). These and other new physics signatures at the LHC produce highly boosted particles, leading to close-by objects in the detector and necessitating jet substructure techniques to disentangle the hadronic decay products. This talk presents the...
We present results from searches for resonances with enhanced couplings to third generation quarks, based on proton-proton collision data at a centre-of-mass energy of 13 TeV recorded by CMS. The signatures include single and pair production of vector-like quarks and heavy resonances decaying to third generation quarks. A wide range of final states, from multi-leptonic to entirely hadronic is...
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