This paper presents a computer code for analyzing electroweak precision data (EWPD) in the framework of the Standard Model Effective Field Theory (SMEFT), highlights the importance of recent ATLAS and CMS precision measurements, and introduces a novel analysis of the forward–backward asymmetry at the LHC. The computer code provides the likelihood of SMEFT Wilson coefficients based on precision measurements of $\textit{W}$ and $\textit{Z}$ pole observables, interpolation formulas for Standard Model predictions, and modular SMEFT parametrizations. SMEFT predictions including next-to-leading-order (NLO) effects in perturbative and SMEFT expansion are available and five alternative electroweak input parameter schemes are supported. The likelihood addresses shortcomings of previous formulations in the treatment of parametric uncertainties and can be straightforwardly included in SMEFT fits of LHC data. The input parameter scheme dependence and role of NLO corrections is studied for the EWPD fit in the SMEFT. Furthermore, the impact of recent ATLAS and CMS measurements — of the $\textit{W}$ boson mass and width, of the lepton flavour universality (LFU) of $\textit{W}$ branching fractions, and the effective leptonic weak mixing angle, $$ {\sin}^2{\theta}_{\textrm{eff}}^{\ell } $$ — is analyzed. A test of LFU that surpasses the precision of existing measurements is proposed based on the $$ {\sin}^2{\theta}_{\textrm{eff}}^{\ell } $$ measurement. Finally, an ATLAS Drell-Yan triple-differential cross-section measurement is reinterpreted in the SMEFT and combined with the EWPD likelihood. This analysis demonstrates the feasibility of the LFU precision test, improves constraints on muon couplings with respect to the world average, and determines a combination of the quark-coupling asymmetry parameters $\textit{A}$ and $\textit{A}$ with a precision comparable to that of the heavy flavour parameters $\textit{A}$ and $\textit{A}$ .

Germany

Hannes Mildner

An EWPD SMEFT likelihood for the LHC — and how to improve it with measurements of W and Z boson properties

A set of measurements for the production of a $$W$$ -boson in association with high-transverse-momentum jets is presented using 140 fb $$^{-1}$$ of proton–proton collision data at a centre-of-mass energy of $$\sqrt{s}=13$$ TeV collected by the ATLAS detector at the LHC. The measurements are performed in final states in which the $$W$$ -boson decays into an electron or muon plus a neutrino and is produced in association with jets with $$p_{\text {T}} {EMPTY}>30$$ GeV, where the leading jet has $$p_{\text {T}} {EMPTY}>500$$ GeV. The angular separation between the lepton and the closest jet with $$p_{\text {T}} {EMPTY}>100$$ GeV is measured and used to define a collinear phase space, wherein measurements of kinematic properties of the $$W$$ -boson and the associated jet are performed. The collinear phase space is populated by dijet events radiating a $$W$$ -boson and events with a $$W$$ -boson produced in association with several jets and it serves as an excellent data sample to probe higher-order theoretical predictions. Measured differential distributions are compared with predictions from state-of-the-art next-to-leading order multi-leg merged Monte Carlo event generators and a fixed-order calculation of the $$W+1$$ -jet process computed at next-to-next-to-leading order in the strong coupling constant.

France

G. Aad

Norway

E. Aakvaag

United States

B. Abbott

United Arab Emirates

S. Abdelhameed

K. Abeling

N. Abicht

S. Abidi

M. Aboelela

Morocco

A. Aboulhorma

Israel

H. Abramowicz

Y. Abulaiti

Italy

United Kingdom

B. Acharya

A. Ackermann

C. Bourdarios

Poland

L. Adamczyk

S. Addepalli

M. Addison

J. Adelman

Türkiye

A. Adiguzel

T. Adye

A. Affolder

Y. Afik

Spain

M. Agaras

A. Aggarwal

Romania

C. Agheorghiesei

Azerbaijan

F. Ahmadov

S. Ahuja

China

X. Ai

G. Aielli

A. Aikot

M. Tamlihat

B. Aitbenchikh

M. Akbiyik

Sweden

T. Åkesson

A. Akimov

Japan

D. Akiyama

N. Akolkar

S. Aktas

G. Alberghi

Canada

J. Albert

P. Albicocco

G. Albouy

S. Alderweireldt

Z. Alegria

Switzerland

M. Aleksa

I. Aleksandrov

C. Alexa

Greece

T. Alexopoulos

F. Alfonsi

M. Algren

M. Alhroob

Czechia

B. Ali

Saudi Arabia

H. Ali

S. Ali

S. Alibocus

South Africa

M. Aliev

G. Alimonti

W. Alkakhi

C. Allaire

B. Allbrooke

J. Allen

Chile

C. Flores

P. Allport

A. Aloisio

Argentina

F. Alonso

C. Alpigiani

Z. Alsolami

A. Fernandez

M. Cardoso

M. Alviggi

M. Aly

Brazil

Y. Coutinho

A. Ambler

C. Amelung

M. Amerl

C. Ames

D. Amidei

B. Amini

K. Amirie

Portugal

S. Santos

K. Amos

D. Amperiadou

S. An

V. Ananiev

C. Anastopoulos

T. Andeen

J. Anders

A. Anderson

A. Andreazza

S. Angelidakis

A. Angerami

A. Anisenkov

A. Annovi

C. Antel

E. Antipov

M. Antonelli

F. Anulli

M. Aoki

T. Aoki

Cross-section measurements for the production of a $$W$$ -boson in association with high-transverse-momentum jets in $\textit{pp}$ collisions at $$\sqrt{s}$$ = 13 TeV with the ATLAS detector

We perform a detailed theoretical study of the rare radiative decay of the $\textit{W}$ boson into a $\textit{B}$ meson and an on-shell photon. The decay amplitude is described by two independent form factors, which are calculated up to the next-to-next-to-leading order (NNLO) in QCD within the nonrelativistic QCD (NRQCD) factorization formalism. Since the two typical energy scales, the $\textit{W}$ -boson mass $\textit{m}$ and the $\textit{B}$ -meson mass $$ {m}_{B_c} $$ , involved in the process are widely separated, large logarithms of $$ {m}_W^2/{m}_{B_c}^2 $$ present in the NRQCD short-distance coefficients are also resummed to all orders in $\textit{α}$ up to the next-to-leading logarithmic (NLL) accuracy, by employing the light-cone factorization approach. Taking into account all these corrections, we then perform a phenomenological exploration of this rare decay. It is found that, relative to the leading-order result, the decay width of the process is reduced by the next-to-leading-order and NNLO corrections, with a net effect of ∼ −19% and of ∼ −31%, respectively. Furthermore, the NLL resummation can considerably alter the fixed-order NRQCD predictions, especially for the 𝒪($\textit{α}$ ) correction. We also find that the radiative corrections increase the renormalization scale dependence of the branching fraction, which is however significantly reduced by the NLL resummation. The dependence of the branching fraction on the heavy-quark masses $\textit{m}$ is also investigated, which shows a monotonic decrease (increase) with $\textit{m}$ ($\textit{m}$ ).

Xin-Qiang Li

Ya-Dong Yang

Yu-Dong Zhang

Dong-Hui Zheng

Rare $\textit{W}$ → $\textit{B}$

High precision single-differential $$W^\pm $$ -boson production cross-sections as a function of electron or muon transverse momentum $$p_\textrm{T}$$ or their pseudorapity $$\eta $$ , as well as double-differential cross-sections as functions of these variables, are measured in proton–proton collisions at centre-of-mass energies $$\sqrt{s}=5.02$$ TeV and 13 TeV. The $\textit{W}$-boson charge asymmetry as a function of lepton $$\eta $$ is also measured. The data, collected in dedicated runs at reduced instantaneous luminosity with the ATLAS detector at the Large Hadron Collider, correspond to integrated luminosities of 255 pb $$^{-1}$$ at 5.02 TeV and 338 pb $$^{-1}$$ at 13 TeV. The measurements are in agreement with Standard-Model predictions calculated at next-to-next-to-leading-order in the strong coupling constant $$\alpha _s$$ including transverse-momentum resummation at next-to-next-to-leading logarithmic accuracy using several parton distribution functions. The impact of the measured differential cross-sections as a function of lepton $$\eta $$ on the determination of these functions is studied using a profiling technique.

M. Ait Tamlihat

A. Alvarez Fernandez

M. Alves Cardoso

Y. Amaral Coutinho

A. Amirkhanov

S. Amor Dos Santos

Measurement of $$W^{\pm }$$ -boson differential cross-sections in proton–proton collisions with low pile-up data at $$\sqrt{s} = 5.02$$ TeV and $$13\,\hbox {TeV}$$ with the ATLAS detector

We compute a complete set of the two-loop Feynman integrals that are required for the next-to-next-to-leading order QCD corrections to on-shell top-pair production in association with a $\textit{W}$ boson at hadron colliders in the leading colour approximation. These Feynman integrals also contribute to Higgs or $\textit{Z}$-boson production in association with a top pair. We employ the method of differential equations (DEs), facilitated by the use of finite field methods to handle the algebraic complexity stemming from the seven-scale kinematics. The presence of the top quark in the virtual propagators, in addition to the mass of the external $\textit{W}$ boson, gives rise to nested square roots and three elliptic curves. We obtain DEs that depend at most quadratically on the dimensional regulator $\textit{ϵ}$ for sectors where these analytic structures appear, and are $\textit{ϵ}$-factorised otherwise. We express the DEs in terms of a minimal set of differential one-forms, separating the logarithmic ones. We solve the DEs numerically in the physical kinematic region, with the method of generalised power series expansions.

Matteo Becchetti

Dhimiter Canko

Vsevolod Chestnov

Tiziano Peraro

Mattia Pozzoli

Simone Zoia

Two-loop Feynman integrals for leading colour $$ t\overline{t}W $$ production at hadron colliders

The top quark mass is a key parameter of the standard model, yet measuring it precisely at the Large Hadron Collider (LHC) is challenging. Inspired by the use of standard candles in cosmology, we propose a novel energy correlator-based observable, which directly accesses the dimensionless quantity <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>t</mi></msub><mo>/</mo><msub><mi>m</mi><mi>W</mi></msub></math>. We perform a Monte Carlo study to demonstrate the feasibility of the top mass extraction from Run 2, 3, and High-Luminosity LHC datasets. Our resulting <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>t</mi></msub></math> can be defined in a well-controlled short-distance mass scheme and exhibits remarkably small uncertainties from nonperturbative effects, as well as insensitivity to parton distribution functions, outlining a roadmap for a record precision measurement at the LHC.

Jack Holguin

Ian Moult

Aditya Pathak

Austria

Massimiliano Procura

Robert Schöfbeck

Dennis Schwarz

Using the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math> Boson as a Standard Candle to Reach the Top: Calibrating Energy-Correlator-Based Top Mass Measurements

We investigate the impact of dimension-8 operators on $\textit{W}$ $\textit{W}$ production at the LHC for the incoming gluon-gluon channel. To this end, we have identified all dimension-8 CP-even operators contributing to the process in question, and computed the corresponding tree-level helicity amplitudes for fully-leptonic decays of the $\textit{W}$ bosons. These are implemented in the program MCFM-RE, which automatically incorporates the effect of a jet-veto to reduce the otherwise overwhelming $$ t\overline{t} $$ background. We find that, unless we break the hierarchy of the effective field theory (EFT), the interference of the dimension-8 operators with the Standard Model is negligible across the considered distributions. This justifies including the square of dimension-6 operators when performing EFT fits with this channel. We then present new constraints on CP-even and CP-odd dimension-6 operators within the EFT regime. Lastly, we postulate a scenario in which the hierarchy of the EFT is broken, justified by the strong constraints on dimension-6 operators from existing on-shell Higgs data. In this scenario, we discuss the constraints that can be reasonably set on CP-even dimension-8 operators with current and future data. We remark that the effect of the jet-veto on the ability to constrain new physics in the $\textit{W}$ $\textit{W}$ channel is quite dramatic and must be properly taken into account.

Daniel Gillies

Andrea Banfi

Adam Martin

Matthew Lim

Dimension-8 operators in $\textit{W}$

We argue that the Standard Model is accompanied by a new pseudoscalar degree of freedom, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>η</mi><mi>w</mi></msub></math> meson, which cancels the topological susceptibility of the electroweak vacuum and gets its mass from this effect. The prediction is based on the analyticity properties of the Chern-Simons correlator combined with the basic features of gravity. Depending on the quality level of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mrow><mo stretchy="false">)</mo></mrow><mrow><mi>B</mi><mo>+</mo><mi>L</mi></mrow></msub></mrow></math> symmetry, the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>η</mi><mi>w</mi></msub></math> emerges as a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo>+</mo><mi>L</mi></math> pseudo-Goldstone boson or as a Stückelberg 2-form of the electroweak gauge redundancy. An intriguing scenario of the first category is the emergence of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>η</mi><mi>w</mi></msub></math> in the form of the phase of a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mrow><mi>B</mi><mo>+</mo><mi>L</mi></mrow></msub></math>-violating fermion condensate triggered by the instantons, somewhat similar to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>η</mi><mo>′</mo></msup></math> meson in QCD. Regardless of its origin, the presence of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>η</mi><mi>w</mi></msub></math> meson in the theory appears to be a matter of consistency.

Gia Dvali

Australia

Archil Kobakhidze

Otari Sakhelashvili

Electroweak <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>η</mi><mi>w</mi></msub></math> meson

We present the first amplitude analysis and branching fraction measurement of the decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><msup><mi>π</mi><mn>0</mn></msup><msup><mi>π</mi><mn>0</mn></msup></math>, using <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> collision data collected with the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>7.33</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>, and report the first observation of the pure <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math>-annihilation decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>ω</mi><msup><mi>ρ</mi><mo>+</mo></msup></math> with a branching fraction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>0.99</mn><mo>±</mo><mn>0.0</mn><msub><mrow><mn>8</mn></mrow><mrow><mi>stat</mi></mrow></msub><msub><mrow><msubsup><mrow><mtext> </mtext></mrow><mrow><mo>−</mo><mn>0.07</mn></mrow><mrow><mo>+</mo><mn>0.05</mn></mrow></msubsup></mrow><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">)</mo><mo>%</mo></mrow></math>. In comparison to the low significance of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">D</mi></math> wave in the decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>ϕ</mi><msup><mi>ρ</mi><mo>+</mo></msup></math>, the dominance of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">D</mi></math> wave over the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">S</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">P</mi></math> waves, with a fraction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>51.85</mn><mo>±</mo><mn>7.2</mn><msub><mrow><mn>8</mn></mrow><mrow><mi>stat</mi></mrow></msub><msub><mrow><msubsup><mrow><mtext> </mtext></mrow><mrow><mo>−</mo><mn>7.90</mn></mrow><mrow><mo>+</mo><mn>4.83</mn></mrow></msubsup></mrow><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">)</mo><mo>%</mo></mrow></math> observed in the decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>ω</mi><msup><mi>ρ</mi><mo>+</mo></msup></math>, provides crucial information for the “polarization puzzle,” as well as for the understanding of charm meson decays. The branching fraction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><msup><mi>π</mi><mn>0</mn></msup><msup><mi>π</mi><mn>0</mn></msup></math> is measured to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>4.41</mn><mo>±</mo><mn>0.1</mn><msub><mrow><mn>5</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0.1</mn><msub><mrow><mn>3</mn></mrow><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">)</mo><mo>%</mo></mrow></math>. Moreover, the branching fraction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>ϕ</mi><msup><mi>ρ</mi><mo>+</mo></msup></math> is measured to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>3.98</mn><mo>±</mo><mn>0.3</mn><msub><mrow><mn>3</mn></mrow><mrow><mi>stat</mi></mrow></msub><msub><mrow><msubsup><mrow><mtext> </mtext></mrow><mrow><mo>−</mo><mn>0.19</mn></mrow><mrow><mo>+</mo><mn>0.21</mn></mrow></msubsup></mrow><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">)</mo><mo>%</mo></mrow></math>, and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>R</mi><mi>ϕ</mi></msub><mo>=</mo><mrow><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>ϕ</mi><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><msup><mi>π</mi><mn>0</mn></msup><mo stretchy="false">)</mo></mrow><mo>/</mo><mrow><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>ϕ</mi><mo stretchy="false">→</mo><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup><mo stretchy="false">)</mo></mrow></math> is determined to be (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>0.222</mn><mo>±</mo><mn>0.01</mn><msub><mrow><mn>9</mn></mrow><mrow><mi>stat</mi></mrow></msub><msub><mrow><msubsup><mrow><mtext> </mtext></mrow><mrow><mo>−</mo><mn>0.016</mn></mrow><mrow><mo>+</mo><mn>0.016</mn></mrow></msubsup></mrow><mrow><mi>syst</mi></mrow></msub></mrow></math>), which is consistent with the previous measurement based on charm meson decays, but deviates from the results from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> annihilation and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mo>−</mo><mi>N</mi></math> scattering experiments by more than <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>3</mn><mi>σ</mi></mrow></math>.

M. Ablikim

Russia

M.N. Achasov

P. Adlarson

O. Afedulidis

X.C. Ai

R. Aliberti

A. Amoroso

Q. An

Y. Bai

JINR

O. Bakina

I. Balossino

Y. Ban

H.R. Bao

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M. Bertani

D. Bettoni

F. Bianchi

E. Bianco

A. Bortone

I. Boyko

Observation of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math>-Annihilation Process <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi>D</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo stretchy="false">→</mo><mi>ω</mi><msup><mrow><mi>ρ</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow></math> and Measurement of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi>ϕ</mi><msup><mi>ρ</mi><mo>+</mo></msup></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><msup><mi>π</mi><mn>0</mn></msup><msup><mi>π</mi><mn>0</mn></msup></math> Decays