Friday, January 25, 2019

ATLAS Run-2 Data Tugs Down Global Higgs Boson Mass Estimate

We have Run-2 top quark mass measurements from CMS and Run-2 Higgs boson measurements from ATLAS in two channels and in one CMS channel (which tugs the global average up by about 0.09 GeV), but combined measurements including Run-2 results for neither mass measurement. 

The Run-2 data from ATLAS pulls the world average down from the 125.09 GeV average from ATLAS and CMS combined based on Run-1 data alone, mostly because the Run-2 diphoton decay channel measurement at ATLAS was significantly lower than the previous measurement.

In all other respects the LHC measurements of the Higgs boson are consistent with the Standard Model expectation to increasing precision, which constrains beyond the Standard Model theories that modify the properties of the Higgs boson.

From here (this is actually old news).

An error weighted average of the new Run-2 CMS data and the new Run-2 ATLAS data, with the Run-1 combined weighted average, yields a new average of 125.08 GeV with a somewhat smaller margin of error than the previous 0.24 GeV. 

A Higgs boson mass of 124.65 GeV, which is notable because it would be the mass at which half of the Higgs vev squared is equal to the sum of the square of the masses of the fundamental Standard Model bosons, is still a value barely consistent with the Run-2 data to date within two sigma.

5 comments:

neo said...

"A Higgs boson mass of 124.65 GeV, which is notable because it would be the mass at which half of the Higgs vev squared is equal to the sum of the square of the masses of the fundamental Standard Model bosons"

is there any physics theories that this is important?

like the koide mass relations

andrew said...

The first published discussion of the relationship of which I am aware is in a paper by Lopez Castro and Pestieau (two people, not three).

If the conjecture is true, it would suggest strong that the fundamental particle set of the SM is complete (at the very least on the boson side), would explain the overall scale of the SM particle masses, would reduce by two the number of fundamental constants, and would predict the top quark mass more precisely than it can be measured.

It can also be stated as the sum of the Yukawas is equal to 1. And implies an equality between the sum of the fundamental fermion Yukawas and the sum of the fundamental boson Yukawas in a manner reminiscent of what supersymmetry tries to do.

Seen in a context where the overall mass scale is set by the Higgs vev, the Koide relation and other relationships between particle masses go only to the relative and not absolute values of the particle masses.

neo said...

such a result does not sound consistent with SUSY which doubles the particle content. yet theorists believe in SUSY.

btw i just saw this paper, below,
can Deur's work reproduce the radial acceleration relation?

this paper and a previous one you posted shows conformal gravity can reproduce both MOND and rar. i suspect that CMB is the result of something like neutron stars or micro black holes, and that MOND/conformal gravity explains galaxy rotations. no need to enlarge the particle content of the SM, except neutrino masses.

https://arxiv.org/abs/1901.01228
Conformal Gravity and the Radial Acceleration Relation
James G. O'Brien, Thomas L. Chiarelli, Mark A. Falcone, Muhannad H. AlQurashi
(Submitted on 18 Dec 2018)

During the 2016 International Workshop on Astronomy and Relativistic Astrophysics (IWARA), the question was raised as to if conformal gravity could explain the timely result of McGaugh et. al. 2016 which showed a universal nature found in the centripetal accelerations of spiral galaxies. At the time of the conference, the McGaugh result was only published for two weeks. Since then, the result has become known as the Radial Acceleration Relation (RAR) and has been considered tantamount to a natural law. In this work, we summarize how conformal gravity can explain the Radial Acceleration Rule in a fashion consistent with the findings of the original authors without the need for dark matter.

andrew said...

"such a result does not sound consistent with SUSY which doubles the particle content. yet theorists believe in SUSY."

SUSY is a failed and sinking ship.

"can Deur's work reproduce the radial acceleration relation?"

Yes. Also I saw this paper and if I haven't blogged about it already, I plan to. I think that I did blog it however.

andrew said...

Previous post on conformal gravity: http://dispatchesfromturtleisland.blogspot.com/2018/12/reproducing-mond-with-conformal-gravity.html