814 citations · 2.1k across the 35 of their papers we have counts for
27 papers · 1 filter
Chiral Measurements
Christopher G. Lester
Searches for parity violation at particle physics collider experiments without polarised initial states or final-state polarimeters lack a formal framework within which some of the…
A method to challenge symmetries in data with self-supervised learning
Rupert Tombs, Christopher G. Lester
Symmetries are key properties of physical models and of experimental designs, but any proposed symmetry may or may not be realized in nature. In this paper, we introduce a practica…
Using unsupervised learning to detect broken symmetries, with relevance to searches for parity violation in nature. (Previously: "Stressed GANs snag desserts")
Christopher G. Lester, Rupert Tombs
Testing whether data breaks symmetries of interest can be important to many fields. This paper describes a simple way that machine learning algorithms (whose outputs have been appr…
Lorentz and permutation invariants of particles I
Ben Gripaios, Ward Haddadin, Christopher G. Lester
A theorem of Weyl tells us that the Lorentz (and parity) invariant polynomials in the momenta of particles are generated by the dot products. We extend this result to include t…
Difference between two species of emu hides a test for lepton flavour violation
Christopher Gorham Lester, Benjamin Hylton Brunt
We argue that an LHC measurement of some simple quantities related to the ratio of rates of e+mu- to e-mu+ events is surprisingly sensitive to as-yet unexcluded R-parity violating…
Bisection-based asymmetric MT2 computation: a higher precision calculator than existing symmetric methods
Christopher G. Lester, Benjamin Nachman
An MT2 calculation algorithm is described. It is shown to achieve better precision than the fastest and most popular existing bisection-based methods. Most importantly, it is also…
Improving estimates of the number of fake leptons and other mis-reconstructed objects in hadron collider events: BoB's your UNCLE. (Previously "The Matrix Method Reloaded")
Thomas P. S. Gillam, Christopher G. Lester
We consider current and alternative approaches to setting limits on new physics signals having backgrounds from misidentified objects; for example jets misidentified as leptons, b-…
Significance Variables
Benjamin Nachman, Christopher G. Lester
Many particle physics analyses which need to discriminate some background process from a signal ignore event-by-event resolutions of kinematic variables. Adding this information, a…
Properties of MT2 in the massless limit
Colin H. Lally, Christopher G. Lester
Although numerical methods are required to evaluate the stransverse mass, MT2, for general input momenta, non-numerical methods have been proposed for some special clases of input…
Finding Higgs bosons heavier than 2 m_W in dileptonic W-boson decays
Alan J. Barr, Ben Gripaios, Christopher G. Lester
We reconsider observables for discovering a heavy Higgs boson (with m_h > 2m_W) via its di-leptonic decays h -> WW -> l nu l nu. We show that observables generalizing the transvers…
A Storm in a "T" Cup
Alan J. Barr, Teng Jian Khoo, Partha Konar +4
We revisit the process of transversification and agglomeration of particle momenta that are often performed in analyses at hadron colliders, and show that many of the existing mass…
Re-weighing the evidence for a Higgs boson in dileptonic W-boson decays
Alan J. Barr, Ben Gripaios, Christopher G. Lester
We reconsider observables for discovering and measuring the mass of a Higgs boson via its di-leptonic decays: H --> WW* --> l nu l nu. We define an observable generalizing the tran…
Guide to transverse projections and mass-constraining variables
A. J. Barr, T. J. Khoo, P. Konar +4
This paper seeks to demonstrate that many of the existing mass-measurement variables proposed for hadron colliders (mT, mEff, mT2, missing pT, hT, rootsHatMin, etc.) are far more c…
Speedy Higgs boson discovery in decays to tau lepton pairs : h->tau,tau
Alan J. Barr, Sky T. French, James A. Frost +1
Discovery of the Higgs boson in any decay channel depends on the existence of event variables or cuts with sensitivity to the presence of the Higgs. We demonstrate the non-optimali…
The impact of the ATLAS zero-lepton, jets and missing momentum search on a CMSSM fit
B. C. Allanach, T. J. Khoo, C. G. Lester +1
Recent ATLAS data significantly extend the exclusion limits for supersymmetric particles. We examine the impact of such data on global fits of the constrained minimal supersymmetri…
The stransverse mass, MT2, in special cases
Christopher G. Lester
This document describes some special cases in which the stransverse mass, MT2, may be calculated by non-iterative algorithms. The most notable special case is that in which the vis…
A Review of the Mass Measurement Techniques proposed for the Large Hadron Collider
Alan J. Barr, Christopher G. Lester
We review the methods which have been proposed for measuring masses of new particles at the Large Hadron Collider paying particular attention to the kinematical techniques suitable…
Measuring Slepton Masses and Mixings at the LHC
Jonathan L. Feng, Sky T. French, Iftah Galon +5
Flavor physics may help us understand theories beyond the standard model. In the context of supersymmetry, if we can measure the masses and mixings of sleptons and squarks, we may…
Transverse masses and kinematic constraints: from the boundary to the crease
Alan J. Barr, Ben Gripaios, Christopher G. Lester
We re-examine the kinematic variable m_T2 and its relatives in the light of recent work by Cheng and Han. Their proof that m_T2 admits an equivalent, but implicit, definition as th…
The Shifted Peak: Resolving Nearly Degenerate Particles at the LHC
Jonathan L. Feng, Sky T. French, Christopher G. Lester +2
We propose a method for determining the mass difference between two particles, \slep_1 and \slep_2, that are nearly degenerate, with Δ{m}, defined as m_2-m_1, being much less than…
Measuring the Higgs boson mass in dileptonic W-boson decays at hadron colliders
Alan J. Barr, Ben Gripaios, Christopher Gorham Lester
It is expected that hadron collider measurements of the Higgs boson mass using the decay h -> W^+W^-, followed by the leptonic decay of each W-boson, will be performed by fitting t…
Weighing Wimps with Kinks at Colliders: Invisible Particle Mass Measurements from Endpoints
Alan J. Barr, Ben Gripaios, Christopher G. Lester
We consider the application of endpoint techniques to the problem of mass determination for new particles produced at a hadron collider, where these particles decay to an invisible…
Sampling using a `bank' of clues
Benjamin C. Allanach, Christopher G. Lester
An easy-to-implement form of the Metropolis Algorithm is described which, unlike most standard techniques, is well suited to sampling from multi-modal distributions on spaces with…
Discovering anomaly-mediated supersymmetry at the LHC
A. J. Barr, B. C. Allanach, C. G. Lester +2
The discovery potential of the LHC is investigated for the minimal anomaly-mediated supersymmetry breaking (mAMSB) scenario, using the ATLAS fast detector simulator, including trac…