Invariant-mass distribution of top-quark pairs and top-quark mass determination *

Ju, Wan-Li; Wang, Guoxing; Wang, Xing; Xu, Xiaofeng; Xu, Yongqi; Yang, Li Lin

doi:10.1088/1674-1137/44/9/091001

“…Of the four cases, this choice provides the greatest sensitivity but remains notably worse than the ATLAS data, as observed in other studies -for comparison, the corresponding ATLAS limits are 172.4 GeV < m t < 173.6 GeV (which remain the same regardless of the CMS distribution included in the fit), while the total cross section provides 171.9 GeV < m t < 175.4 GeV (which varies by at most 0.2 GeV on the upper and lower bounds as the CMS distribution is altered). The fact that the CMS M t t and p T t distributions are generally better able to constrain m t is expected based on theoretical grounds [34,82,83] and has also been demonstrated in e.g. Ref.…”

Section: Choices Of Cms Distributionmentioning

confidence: 65%

Constraining the top-quark mass within the global MSHT PDF fit

Cridge,

Lim

2023

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We examine the ability of experimental measurements of top-quark pair production to constrain both the top-quark mass and the strong coupling within the global MSHT parton distribution function (PDF) fit. Specifically, we consider ATLAS and CMS measurements of differential distributions taken at a centre-of-mass energy of 8 TeV, as well as $$ t\bar{t}$$ t t ¯ total cross section data taken at a variety of experiments, and compare to theoretical predictions including next-to-next-to-leading order corrections. We find that supplementing the global fit with this additional information results in relatively strong constraints on the top-quark mass, and is also able to bound the strong coupling in a limited fashion. Our final result is $$m_t=173.0\pm 0.6~\textrm{GeV}$$ m t = 173.0 ± 0.6 GeV and is compatible with the world average pole mass extracted from cross section measurements of $$172.5\pm 0.7~\textrm{GeV}$$ 172.5 ± 0.7 GeV by the Particle Data Group. We also study the effect of different top-quark masses on the gluon parton distribution function, finding changes at high x which nonetheless lie within the large PDF uncertainties in this region.

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“…Of the four cases, this choice provides the greatest sensitivity but remains notably worse than the ATLAS data, as observed in other studies -for comparison, the corresponding ATLAS limits are 172.4 GeV < m t < 173.6 GeV (which remain the same regardless of the CMS distribution included in the fit), while the total cross section provides 171.9 GeV < m t < 175.4 GeV (which varies by at most 0.2 GeV on the upper and lower bounds as the CMS distribution is altered). The fact that the CMS M t t and p T t distributions are generally better able to constrain m t is expected based on theoretical grounds [34,79,80] and has also been demonstrated in e.g. ref.…”

Section: Choices Of Cms Distributionmentioning

confidence: 60%

PDF4LHC21: Update on the benchmarking of the CT, MSHT and NNPDF global PDF fits

Cridge

¹

2022

SciPost Phys. Proc.

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There have been recent updates to the three global PDF fits (CT, MSHT and NNPDF), all adding large amounts of data from the LHC, and this has resulted in significant changes to the global PDFs. Given the impact that the new PDFs will have on physics comparisons at the LHC, it is crucial to perform a benchmarking among the PDFs, similar in spirit to that which was carried out for PDF4LHC15, widely used for LHC physics. In this article we detail a benchmarking comparison of three global PDF sets - CT18, MSHT20 and NNPDF3.1 - and their similarities and differences that have been observed. The end result of this study will be a new PDF4LHC21 ensemble of combined PDFs suitable for a wide range of LHC applications.

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“…Along with the progress made in fixed-order calculations, in a bid to improve the perturbative convergence and in turn the predictivity of the theoretical results, resummed calculations have also been carried out within a variety of frameworks and the kinematical limits. Examples include the mechanic threshold [46][47][48][49][50][51][52][53][54][55][56], the top-quark pair production threshold [57][58][59][60][61][62][63], the low transverse momentum domain [64][65][66][67][68], and the narrow jettiness regime [69]. Very recently, the combination of the fixed-order results with a parton shower has been discussed in [70,71].…”

Section: Introductionmentioning

confidence: 99%

Projected transverse momentum resummation in top-antitop pair production at LHC

Ju

¹

,

Schoenherr

²

2023

J. High Energ. Phys.

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The transverse momentum distribution of the $$ t\overline{t} $$ t t ¯ system is of both experimental and theoretical interest. In the presence of azimuthally asymmetric divergences, pursuing resummation at high logarithmic precision is rather demanding in general. In this paper, we propose the projected transverse momentum spectrum $$ \textrm{d}{\sigma}_{t\overline{t}}/\textrm{d}{q}_{\tau } $$ d σ t t ¯ / d q τ , which is derived from the classical $$ {\overrightarrow{q}}_{\textrm{T}} $$ q → T spectrum by integrating out the rejection component $$ {q}_{\tau_{\perp }} $$ q τ ⊥ with respect to a reference unit vector $$ \overrightarrow{\tau} $$ τ → , to serve as an alternative solution to remove these asymmetric divergences, in addition to the azimuthally averaged case $$ \textrm{d}{\sigma}_{t\overline{t}}/\textrm{d}\mid {\overrightarrow{q}}_{\textrm{T}}\mid $$ d σ t t ¯ / d ∣ q → T ∣ . In the context of the effective field theories, SCETII and HQET, we will demonstrate that in spite of the $$ {q}_{\tau_{\perp }} $$ q τ ⊥ integrations, the leading asymptotic terms of $$ \textrm{d}{\sigma}_{t\overline{t}}/\textrm{d}{q}_{\tau } $$ d σ t t ¯ / d q τ still observe the factorisation pattern in terms of the hard, beam, and soft functions in the vicinity of qτ = 0 GeV. Then, with the help of the renormalisation group equation techniques, we carry out the resummation at NLL+NLO, N2LL+N2LO, and approximate N2LL′+N2LO accuracy on three observables of interest, $$ \textrm{d}{\sigma}_{t\overline{t}}/d{q}_{\textrm{T},\textrm{in}},\textrm{d}{\sigma}_{t\overline{t}}/\textrm{d}{q}_{\textrm{T},\textrm{out}} $$ d σ t t ¯ / d q T , in , d σ t t ¯ / d q T , out , and $$ \textrm{d}{\sigma}_{t\overline{t}}/d\Delta {\phi}_{t\overline{t}} $$ d σ t t ¯ / d Δ ϕ t t ¯ , within the domain $$ {M}_{t\overline{t}} $$ M t t ¯ ≥ 400 GeV. The first two cases are obtained by choosing $$ \overrightarrow{\tau} $$ τ → parallel and perpendicular to the top quark transverse momentum, respectively. The azimuthal de-correlation $$ \Delta {\phi}_{t\overline{t}} $$ Δ ϕ t t ¯ of the $$ t\overline{t} $$ t t ¯ pair is evaluated through its kinematical connection to qT,out. This is the first time the azimuthal spectrum $$ \Delta {\phi}_{t\overline{t}} $$ Δ ϕ t t ¯ is appraised at or beyond the N2LL level including a consistent treatment of both beam collinear and soft radiation.

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Invariant-mass distribution of top-quark pairs and top-quark mass determination *

Cited by 5 publications

References 57 publications

Constraining the top-quark mass within the global MSHT PDF fit

Constraining the top-quark mass within the global MSHT PDF fit

PDF4LHC21: Update on the benchmarking of the CT, MSHT and NNPDF global PDF fits

Projected transverse momentum resummation in top-antitop pair production at LHC

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