Jets from massive unstable particles: Top-mass determination

By S. Fleming, A. Hoang, S. Mantry, Iain W. Stewart. 2007

215 citations recorded by the source corpus.

We construct jet observables for energetic top quarks that can be used to determine a short-distance top quark mass from reconstruction in e+e- collisions with accuracy better than LambdaQCD. Using a sequence of effective field theories we connect the production energy, mass, and top width scales, Q>>m>>Gamma, for the top jet cross section, and derive a QCD factorization theorem for the top invariant mass spectrum. Our analysis accounts for alphas corrections from the production and mass scales, corrections due to constraints in defining invariant masses, nonperturbative corrections from the cross talk between the jets, and alphas corrections to the Breit-Wigner line shape. This paper mainly focuses on deriving the factorization theorem for hemisphere invariant mass distributions and other event shapes in e+e- collisions applicable at a future linear collider. We show that the invariant mass distribution is not a simple Breit-Wigner function involving the top width. Even at leading order it is shifted and broadened by nonperturbative soft QCD effects. We predict that the invariant mass peak position increases linearly with Q/m due to these nonperturbative effects. They are encoded in terms of a universal soft function that also describes soft effects for massless dijet events. In a future paper we compute alphas corrections to the jet invariant mass spectrum, including a summation of large logarithms between the scales Q, m, and Gamma.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/cd0f0f7ea99b0052cabc575cde267ef885d33cf9

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In Nuclear and High Energy Physics

1. A. Larkoski
2. I. Moult
3. Jesse Thaler
4. Benjamin Nachman
5. D. Neill
6. G. Salam
7. G. Soyez
8. Cms Collaboration

Citations in the corpus

• Power-enhanced leading-logarithmic QED corrections to Bq→ μ+μ− (2019, methodology): “This could be achieved by introducing another EFT below the muon-mass scale similar to the SCET treatment of soft radiation in top-quark jets [46].”
• Jet substructure at the Large Hadron Collider: A review of recent advances in theory and machine learning (2017, methodology): “In the case that the top quark decays inclusively into a jet whose mass is measured, a rigorous factorization theorem can be proven for the case of e+e− → dijets [62, 63].”
• Combining higher-order resummation with multiple NLO calculations and parton showers in GENEVA (2012, unknown): “The singular contribution is given by [64, 65]”
• Analytic boosted boson discrimination (2015, background): “A rigorous factorization will also prove essential in this case, allowing for the separation of perturbative and non-perturbative physics, as well as effects associated with the finite top width [111, 174].”
• Jet shapes and jet algorithms in SCET (2010, methodology): “Using this formalism, the factorization and calculation of two-jet cross sections and event shape distributions in SCET were developed in [26, 27, 28, 29].”
• N-jettiness subtractions for NNLO QCD calculations (2015, unknown): “J H E P 0 9 ( 2 0 1 5 ) 0 5 8 quarks [114–119].”
• Resummation of heavy jet mass and comparison to LEP data (2010, methodology): “The hemisphere soft function has been studied briefly in [ 5 , 6, 27] and more thoroughly in [22].”
• General-purpose event generators for LHC physics (2011, unknown): “For more technical details we refer to the literature and in particular [376–379], whose approach we largely follow.”
• Factorization for groomed jet substructure beyond the next-to-leading logarithm (2016, background): “J H E P 0 7 ( 2 0 1 6 ) 0 6 4 The factorization theorem for ungroomed hemisphere energy correlation functions is [39, 52, 53]”
• Factorization at the LHC: From parton distribution functions to initial state jets (2010, methodology): “For comparison, the hemisphere soft function with outgoing Wilson appearing in the double-differential hemisphere invariantmass distribution in e+e− → 2 jets [93, 94, 116, 128, 129, 157] is S hemi(k + a , k + b ) = 1 Nc tr 〈 0 ∣T [ Ỹ † na Ỹnb ] δ(k a − na ·p̂a,s) δ(k b − nb ·p̂b,s)T [ Ỹ † nb Ỹna ]∣0”
• A Practical Seedless Infrared Safe Cone Algorithm a (2007, background): “Jet-masses are potentially of interest for QCD studies, particle mass measurements [34] and new physics searches, where they could be used to identify highly boosted W/Z/H bosons or top quarks produced in the decays of new heavy particles [35].”
• Jet shapes with the broadening axis (2014, background): “11) is identical in form to the familiar thrust factorization theorem [57, 58].”
• Factorization at the LHC: From PDFs to Initial State Jets (Ph.D. thesis) (2009, methodology): “e used parity to switch n b;a back to n a;b. For comparison, the hemisphere soft function with outgoing Wilson appearing in the double-dierential hemisphere invariantmass distribution in e+e !2 jets [93, 94, 116, 128, 129, 157] is Sqq hemi (k + a;k b ) = 1 N c tr 0 T Y ey naY n b (k a n a^p a;s)(k+ ”