arXiv subjects

Keith Pedersen

Publications and source records attributed to Keith Pedersen.

7 recordsLinked to original sources

arXiv2025

A formalism for constructing the QCD power spectrum with finite sampling

Recent progress in the study of QCD phenomena with energy correlators motivates novel approaches to explore the information contained in the QCD radiation spectrum. Fox-Wolfram moments are a set of observables that characterize the angular distribution of energy flow in high-energy collisions. Contrary to their conventional application, they are a class of correlated moments that cannot be reduced to one or several characteristic ones. We present a formalism to extract their fully correlated information content, while systematically discarding small-angle sampling noise, on an event-by-event basis. We show that our approach circumvents a common misspecification of the data in terms of $\delta$-distributions, and is essential in keeping the power spectrum infrared and collinear safe. Our formalism introduces a means of accounting for the varying spatial extent of objects that enter the calculation of the power spectrum, with which experimental artifacts such as detector element geometries and measurement uncertainties can readily be incorporated.

hep-ph↗

arXiv2023

Harnessing the global correlations of the QCD power spectrum

As multiplicity increases at the CERN Large Hadron Collider, an opportunity arises to explore the information contained in the full QCD power spectrum on an event-by-event basis. This paper lays the foundations for a framework to encode and extract the information contained in finite sampling of a QCD event.

hep-ph↗

arXiv2017

Spherical harmonics for multiparticle final states

We examine collider physics via the spectral power H_l, which utilizes much more detector information than sequential jet reconstruction. We use H_l to define a novel jet definition and use it to reconstruct both e+e- > qqg and e+e > tt final states. We find that a significant amount of pileup can be trivially subtracted from H_l jets, provided that the "shape" of pileup can be determined ahead of time. Finally, we find that future progress with H_l jets will require the addition of degrees of freedom accounting for jet "shape" (e.g. radial energy distribution). This should allow the measurement of jet shapes using much more information than traditional techniques.

hep-ph↗

arXiv2017

Reconditioning your quantile function

Monte Carlo simulation is an important tool for modeling highly nonlinear systems (like particle colliders and cellular membranes), and random, floating-point numbers are their fuel. These random samples are frequently generated via the inversion method, which harnesses the mapping of the quantile function Q(u) (e.g. to generate proposal variates for rejection sampling). Yet the increasingly large sample size of these simulations makes them vulnerable to a flaw in the inversion method; Q(u) is ill-conditioned in a distribution's tails, stripping precision from its sample. This flaw stems from limitations in machine arithmetic which are often overlooked during implementation (e.g. in popular C++ and Python libraries). This paper introduces a robust inversion method, which reconditions Q(u) by carefully drawing and using uniform variates. pqRand, a free C++ and Python package, implements this novel method for a number of popular distributions (exponential, normal, gamma, and more).

stat.CO↗

arXiv2016

Probing the two Higgs doublet wedge region with charged Higgs boson decays to boosted jets

Two Higgs doublet extensions of the standard model, such as supersymmetry, predict the existence of charged Higgs bosons. We explore the reach for TeV-scale charged Higgs bosons through their associated production with top quarks, and their decay to boosted top jets and $\mu_x$ tagged boosted bottom jets, at a 14 TeV CERN Large Hadron Collider and at a 100 TeV Future Circular Collider. In particular, we show the moderate $\tan\beta$ "wedge" region of parameter space cannot be probed at the Large Hadron Collider for TeV-scale $H^\pm$ because the cross section is too small. However, a 100 TeV future proton collider can close the wedge region below 2 TeV, and search for $H^\pm$ up to 6 TeV.

hep-ph↗

arXiv2015

Mu_x boosted-bottom-jet tagging and Z-prime boson searches

We present a new technique for tagging heavy-flavor jets with p_T > 500 GeV called "mu_x tagging." Current track-based methods of b-jet tagging lose efficiency and experience a large rise in fake rate in the boosted regime. Using muons from B hadron decay, we combine angular information and jet substructure to tag b jets, c jets, light jets, and "light-heavy" jets (those containing B hadrons from gluon splitting). We find tagging efficiencies of epsilon_b = 14%, epsilon_c = 6.5%, epsilon_{light-light} = 0.14%, and epsilon_{light-heavy} = 0.5%, respectively, that are nearly independent of transverse momentum at high energy. We demonstrate the usefulness of this new scheme by examining the discovery potential for multi-TeV leptophobic Z-prime bosons in the boosted-b-tagged dijet channel at the Large Hadron Collider.

hep-ph↗

arXiv2015

Flavor tagging TeV jets for BSM and QCD

We present a new scheme for tagging high-$p_{T}$ bottom and charm jets using energetic muons. Contemporary track-based $b$ tags lose their ability to reject light jet background as jet $p_{T}\rightarrow\mathcal{O}(\mathrm{TeV})$, where the massive boost exposes fundamental limits in tracking resolution. For our "$\mu_{x}$" tag, the signal efficiency and light jet rejection is robust versus $p_{T}$. In the tested regime (jet $p_{T}\in[\mathrm{0.5,2.1}]$ TeV), $\mu_{x}$ tags $\sim14\%$ of $b$ jets, $\sim6.5\%$ of $c$ jets and $\sim0.65\%$ of light jets. Since $\mu_{x}$ tagging should be immediately useful in a searches for heavy resonances, we test it with a typical dijet search --- a heavy, leptophobic $Z^{\prime}$.

hep-ph↗