Measurement of the cross section of W-boson pair production at LEP

232

214

The ATLAS and CMS collaborations have recently released significant new data on Higgs and diboson production in LHC Run 2. Measurements of Higgs properties have improved in many channels, while kinematic information for h → γγ and h → ZZ can now be more accurately incorporated in fits using the STXS method, and W + W − diboson production at high p T gives new sensitivity to deviations from the Standard Model. We have performed an updated global fit to precision electroweak data, W + W − measurements at LEP, and Higgs and diboson data from Runs 1 and 2 of the LHC in the framework of the Standard Model Effective Field Theory (SMEFT), allowing all coefficients to vary across the combined dataset, and present the results in both the Warsaw and SILH operator bases. We exhibit the improvement in the constraints on operator coefficients provided by the LHC Run 2 data, and discuss the correlations between them. We also explore the constraints our fit results impose on several models of physics beyond the Standard Model, including models that contribute to the operator coefficients at the tree level and stops in the MSSM that contribute via loops.

“…The original experimental results can be found in Refs. [43][44][45][46], and we use the SM predictions from Ref. [44,45].…”

Section: Data Used In the Global Fitmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Updated global SMEFT fit to Higgs, diboson and electroweak data

Ellis¹,

Murphy²,

You³

et al. 2018

232

214

“…(1.2) applied to each hemisphere of an e + e − event 21. The only experimental measurements of spherocity that we know of are in refs [72][73][74]…”

mentioning

confidence: 99%

Jet shapes with the broadening axis

Larkoski

Neill

Thaler

2014

165

249

Broadening is a classic jet observable that probes the transverse momentum structure of jets. Traditionally, broadening has been measured with respect to the thrust axis, which is aligned along the (hemisphere) jet momentum to minimize the vector sum of transverse momentum within a jet. In this paper, we advocate measuring broadening with respect to the "broadening axis", which is the direction that minimizes the scalar sum of transverse momentum within a jet. This approach eliminates many of the calculational complexities arising from recoil of the leading parton, and observables like the jet angularities become recoil-free when measured using the broadening axis. We derive a simple factorization theorem for broadening-axis observables which smoothly interpolates between the thrust-like and broadening-like regimes. We argue that the same factorization theorem holds for two-point energy correlation functions as well as for jet shapes based on a "winner-take-all axis". Using kinked broadening axes, we calculate event-wide angularities in e + e − collisions with next-to-leading logarithmic resummation. Defining jet regions using the broadening axis, we also calculate the global logarithms for angularities within a single jet. We find good agreement comparing our calculations both to showering Monte Carlo programs and to automated resummation tools. We give a brief historical perspective on the broadening axis and suggest ways that broadening-axis observables could be used in future jet substructure studies at the Large Hadron Collider.

“…• LEPII W + W − : we use all the data and SM predictions ( [57][58][59][60]) from tables 12, 13, 14 and 15 of ref. [61], and the definitions of the observables in terms of SMEFT parameters from tables 2 and 3 of the same reference.…”

Section: Jhep12(2020)113mentioning

confidence: 99%

The impact of flavour data on global fits of the MFV SMEFT

Aoude

Hurth

Renner

et al. 2020

We investigate the information that can be gained by including flavour data in fits of the Standard Model Effective Field Theory (SMEFT) with the assumption of Minimal Flavour Violation (MFV), allowing — as initial conditions at the high scale — leading terms in spurionic Yukawas only. Starting therefore from a theory with no tree level flavour changing neutral currents at the scale of new physics, we calculate effects in flavour changing processes at one loop, and the resulting constraints on linear combinations of SMEFT coefficients, consistently parameterising the electroweak parameters and the CKM within the SMEFT. By doing a global fit including electroweak, Higgs and low energy precision measurements among others, we show that flavour observables put strong constraints on previously unconstrained operator directions. The addition of flavour data produces four independent constraints at order TeV or above on otherwise flat directions; reducing to three when complete U(3)5 flavour symmetry is assumed. Our findings demonstrate that flavour remains a stringent test for models of new physics, even in the most flavourless scenario.