Does Higher Measured Particle Mass For The W- Boson Really Mean A "New Physics"?

                   Particles of the Standard Model- note lowest line for Gauge bosons.

 

In my 2000 book, The Atheist's Handbook To Modern Materialism,  e.g.

I showed  the mass of bosons in a Table (B) on p. 232, with the W +  boson masses specified by the (then) masses allowed by the Standard Model.  The W bosons mediate the weak interaction, one of the fundamental forces in physics. Because the Standard Model  of particle physics places tight constraints on the mass of the W boson, then any significant deviation forces us to re-examine that model.  

Elaborating a bit: this so-called 'Standard Model' is generally defined as the symmetry:

SU(3) x SU(2) X U(1)

where each of the above denotes a specific matrix, or more exactly a group. See, e.g.

http://brane-space.blogspot.com/2010/04/looking-at-groups.html

In the case of SU(2) we describe it as the "special unitary group" which has the form:

S =

(a.........-b*)
(b..........a*)

where a*, b* are complex conjugates and we have (aa* + b*b) = 1. Thus the elements of SU(2) are the unitary 2 x 2 matrices with DET (determinant) = 1. These groups thus define the behavior of a specific class of subatomic particles. (Refer to upper graphic)  Spontaneous symmetry breaking would therefore resolve this combination into constituent parts, e.g.: SU(3) associated with the 'color force' of quarks. Similarly we have:

 SU(2) x U(1)

associated with the electro-weak force where the W bosons enter.  One possible symmetry breaking (quark -boson format) is:

SU(3) x SU(2) X U(1) -> SU(3) + SU(2) x U(1)

In the foregoing, the synthesis of SU(2) and U(1) into the locally gauge invariant electro-weak theory requires a mechanism which confers mass to three vector bosons while leaving the photon massless. This 'mass-giving' mechanism is called the Higgs Field or Higgs mechanism, and it demands the existence of one or more massive, spin-0 bosons otherwise called Higgs bosons.  These were discovered independently on July 4, 2012 with observed mass  »  125 GeV.  Just over a year later, the Nobel Prize in Physics was awarded for the discovery.  All seemed right with the universe and the place of the Standard Model in physics. 

 But even in the wake of the awards vexing questions and uncertainties remained. As I wrote in a Oct. 9, 2013 post: 

"The CERN results were mostly based on measurements of two or three of the dozen different ways, or “channels,” by which a Higgs boson could be produced and then decay. Worse, there were hints that some of the channels were overproducing the Higgs while others might have been underproducing. In either case, false positives or false negatives, one had to look askance at the initial results."  

I then noted the unsettling upshot was there may not have been a real Higgs discovered but a spurious 'mirage' imitating some of its properties but more a confection of the data than based in reality.  Flash forward to the present and a recent Fermi Lab mass result for the W boson of 80.433 Mev (million electron volts, where 1 eV  = 1.6 x 10 ^-19 J so 1 Mev = 1.6 x 10 ^-13 J).  

This is nearly 76 Mev higher than the  Standard Model-based mass. While it appears to be a negligible difference, a 7 standard deviation divergence is a big one in the subatomic realm.  In the words of one Duke University physicist - a project leader for the analysis - it was "like discovering a hidden room in your home."   That sounds a bit dramatic but still not far from the truth based on a particle physicist's perspective.  Further, the difference in mass from the prevailing (SM) theory is too large to be a rounding error or anything easily explained away.   If confirmed, indeed, it presents one of the biggest problems for the Standard Model, and I'd argue rivaling or surpassing the Higgs uncertainties.  (Though some particle specialists believe the two results may be somehow tied.)

Of course, one exotic interpretations enter they also will need to have a firm physical basis, not merely remain speculation. Thus, the idea that there is a hitherto undetected particle interacting with the W bosons that can explain the difference will itself need to be explained.  Also, the conjecture that dark matter itself may be playing a role.   Most extreme would be invoking any "new physics" to try to extract a compelling explanation. Which, in my opinion. commits the logical fallacy of ignotum per ignotius, or invoking the less well understood to explain the not well understood.

To be sure, the Standard model isn't perfect, and nowhere near the sophistication of the quantum theory. After all, it remains unable to account fully  for dark matter, dark energy or gravity. If then particle physicists are forced to tinker with the SM to explain these W boson higher mass findings they need to make sure other aspects aren't thrown out of whack.   That includes the equations, mathematical relations (some of which I showed earlier) that currently explain the origin of the quarks, color forces,  antiparticles, etc. 

For sure, there will now be much more intense scrutiny of the Standard model especially given last year's findings by another team (from a year ago) uncovering problems in how muons react, see e.g.

Is the standard model broken? Physicists cheer major muon result (nature.com)