Tuesday, August 15, 2023

A New Higgs Boson Mass Measurement

The current Particle Data Group global average measurement for the Higgs boson mass is 125.25 ± 0.17 GeV. 

The previous combined ATLAS Higgs boson mass measurement (via the Particle Data Group) was 124.86 ± 0.27 GeV from 2018 (using Run 2 data), and the previous combined CMS Higgs boson mass measurement (from the same source) was 125.46 ± 0.16 GeV from 2020 (using Run 2 data). These measurement were consistent with each other at the 1.9 sigma level. The Run-1 measurement from ATLAS and CMS combined (from the same source) was 125.09 ± 0.24 GeV.

The new ATLAS diphoton decay channel Higgs boson mass measurement is 125.17 ± 0.14 GeV. The new ATLAS combined Higgs boson mass measurement is 125.22 ± 0.14 GeV.  

The new ATLAS combined measurement is consistent with the old CMS combined Run-2 measurement at the 1.1 sigma level. 

The new measurement should pull up the global average measurement of the Higgs boson mass to about 125.27 GeV and should also reduce the uncertainty in the global average measurement to ± 0.13 GeV or less. This is an uncertainty of roughly one part per thousand.
The mass of the Higgs boson is measured in the H→γγ decay channel, exploiting the high resolution of the invariant mass of photon pairs reconstructed from the decays of Higgs bosons produced in proton-proton collisions at a centre-of-mass energy s√=13 TeV. The dataset was collected between 2015 and 2018 by the ATLAS detector at the Large Hadron Collider, and corresponds to an integrated luminosity of 140 fb−1. The measured value of the Higgs boson mass is 125.17±0.11(stat.)±0.09(syst.) GeV and is based on an improved energy scale calibration for photons, whose impact on the measurement is about four times smaller than in the previous publication. A combination with the corresponding measurement using 7 and 8 TeV pp collision ATLAS data results in a Higgs boson mass measurement of 125.22±0.11(stat.)±0.09(syst.) GeV. With an uncertainty of 1.1 per mille, this is currently the most precise measurement of the mass of the Higgs boson from a single decay channel.
ATLAS Collaboration, "Measurement of the Higgs boson mass with H→γγ decays in 140 fb−1 of s√=13 TeV pp collisions with the ATLAS detector" arXiv:2308.07216 (August 14, 2023) (submitted to Phys. Lett. B).

4 comments:

andrew said...

At a 125.27 GeV Higgs boson mass, the LP&C relationship (i.e. that the sum of the Higgs Yukawas in the SM equals 1) prefers a top quark mass of 173.6 GeV which is in a roughly 3 sigma tension with the PDG value. Allowing both the Higgs boson mass and the top quark mass to vary within their uncertainties brings the tension between experimental results and the LP&C hypothesis to about 2.8 to 2.9 sigma, which is fairly mild tension.

Graham Dungworth said...

This result appears to better conform to the hypothesis that the Higgs boson is a composite state
eg. 2H= W+ + W- + Z

[1502.06438] A Higgs Boson Composed of Gauge Bosons
arXiv
https://arxiv.org › hep-ph
by FJ Himpsel · 2015 · Cited by 3 — That immediately determines the mass of the composite Higgs boson. It becomes simply half of the vacuum ... From: Franz Himpse

andrew said...

I've seen the paper and I am familiar with the hypothesis. I think it may hurt the hypothesis more than helping it by narrowing the uncertainty in the measurement. Notably, no one has published anything since 2015 on what the predicted mass adjustment from a composite state would be.

andrew said...

The link to the paper is https://arxiv.org/abs/1502.06438