Wednesday, January 09, 2008

Higgs Mass and Current Issues

For example, theory says that Higgs particles are matter particles, but in most respects the Higgs behaves more like a new force than like a particle. How can this be? In truth, the Higgs is neither matter nor force; the Higgs is just different.

A least-square fit to a number of precisely known data in electroweak physics using the Standard Model as theoretical framework and the Higgs mass as a free parameter yields an expectation value for the Higgs mass around the minimum of the parabola. [Source: Precision Electroweak Measurements and Constraints on the Standard Model by the LEP Collaborations and the LEP Electroweak Working Group, arXiv: 0712.0929v2, Figure 5.]
See Backreaction for explanation. The Higgs Mass

It is an exercise for me coming across different informations on the Higg's for a better understanding of the way things are to happen in reality. I hope to provide for extra links to help one understand the potential realizations that come across as I learn to understand this field better.

I appreciate the clarity given to the writing here that allows this deeper understanding of what is taking place by the different commentors, commenting to Back reactions blog post entry.

At 9:07 AM, January 05, 2008, Anonymous a quantum diaries survivor said...

Hi Stefan,

I wish to pay a tribute to your nice post here and answer the question you pose about the counter-intuitive trend of discovery reach at the LHC versus Higgs mass (for a given integrated luminosity), waiting for Michael's posts on the Higgs.

The problem is that as the Higgs mass changes, the mixture of possible final states it decays into changes dramatically. So, while at 160 GeV the Higgs is best sought in its decay to a pair of real W bosons (which weigh 80 GeV each), and in that case backgrounds are small because the signature is very distinctive, at 115 GeV the Higgs mostly decays to a pair of b-quark jets. Seeing a bump in the jet-jet mass distribution is utterly out of the question because in that case backgrounds are HUGE. So one has to rely on very rare decays such as H->gamma gamma - which still is plagued by large backgrounds.

The Higgs search is not one, but ten different analyses, depending on the unknown parameter M_h. Each analysis has its own problems. The higher the Higgs mass, the smaller the number of produced events; but as M_h changes, the signature varies from invisible to highly distinctive. Above 180 GeV, a Higgs can be seen with no trouble in the ZZ final state, when four muons are a gold-plated signature. It is not by chance that CMS was originally conceived as a compact muon solenoid: muons are all you need, at high mass, for the Higgs.


You can find many more explanations here to help any layman in their understanding as T is always quite help in that direction. Also check out his label of "higgs search" at the top of his page.

  • The Higg's Boson and Memory?

  • Alice and the Cosmic Ballet, Now Meet Higgins
  • No comments:

    Post a Comment