CDF measures W mass higher than predicted

[sysprog]

@vanhees71, one of the most contributional guys (Mr. S. Metz) on bit.listserv.ibm-main (IBM mainframe topics) said to me that while he appreciated Emmy Noether's work for its value to physicists, he as a mathematics professor much more was appreciative of her especially great work in abstract algebra $-$
just sayin' .

 

[vanhees71]

That's Emmy Noether's own point of view too. Famously she called her own early work on the "theory of invariants" as "Scheißdreck" ;-)).

 

[ohwilleke]

A new paper discussing CMS data at the LHC describes the statistical and systemic error margins in its next W boson mass measurements that will be possible with new ways of analyzing it (roughly ± 12 MeV total uncertainty with ± 9 MeV which is statistical), but doesn't provide a central value since that data is blinded. It also has a data summary chart.

 

[mfb]

Want to bet the unblinded result will agree with D0/ATLAS/LHCb and the electroweak fit, but not with CDF?

 

[Orodruin]

Want to bet the unblinded result will agree with D0/ATLAS/LHCb and the electroweak fit, but not with CDF?

Depends on what odds you give me ...

 

[ohwilleke]

Want to bet the unblinded result will agree with D0/ATLAS/LHCb and the electroweak fit, but not with CDF?

I'd only bet that it would agree with CDF if you were my nephew and I wanted to give you a birthday present in a cute and novel way. (And, if you really are my nephew, you'd better fess up.)

 

[mfb]

The university of Pisa has created a postdoc position dedicated to W mass measurements with CMS.
They want to avoid most systematic uncertainties by using less model-dependent measurements. That needs much more statistics, but it avoids the limitation to low-pileup runs so CMS can use far larger datasets.

 

[Vanadium 50]

The LHC is a completely different kettle of fish. You have many, many more W's which is good, Each W event is on top of dozens of other events, which is bad. There are also some subtleties involving calibrating on the Z.

 

[ohwilleke]

There is a new preprint from the Tevatron-LHC W boson mass working group which is basically reanalyzing the reanalyzed Tevatron data (although it purports to reanalyze all of the results) with the predictable result that the Tevatron measurement is adjusted downward to a value closer to the rest of the measurements (although it appears that only part of the process of adjustment has been completed).

https://arxiv.org/abs/2211.12365

 

[Orodruin]

with the predictable result that the Tevatron measurement is adjusted downward to a value closer to the rest of the measurements

Oh no! What a surprise!

(Not)

 

[Vanadium 50]

It's a conference proceedings, not a paper, so what can be learned from it has the usual limitations/

What a surprise

Well, to be fair, it had only two directions it could move in.

To be clear, this is NOT, as some people have claimed, a reanalysis. It is an early step of averaging multiple measurements. It says so on the very first line. Furthermore, as the paper itself says on the very first page is that this step is to get all the experimental results to use the same reference model.

One of the complications here is that "the W mass" is neither well-defined at the level of precision needed to be interesting, nor is it the quantity of theoretical interest. That is the electroweak component of the W mass, which granted, is 99.9+% of the contribution, but is more in the category of "parameter of the theory" than "physical quantity".

So if the resolution to all of this is that the pre-averaginhg corrections move the CDF results closer to the average, it would not be wrong to say that the issue is not the fundamental physics, but the differences in what exactly is being measured.

 

[PeterDonis]

Thread closed for moderation.

 

[PeterDonis]

The thread has run its course and will remain closed. Thanks to all who participated!