Folks,
I have been following the discussion of the changes to the main statement of the energy frontier report.
Markus did a great job, especially in crystalizing the main message to be put in italics. I must say that
I like Markus' version better than Chip's. It is the ideas, more than the theories, that are compelling.
I agree with Ashutosh, Chip, and others that "potentially" can be omitted. It is clear from the text
that these are bold theories that might be wrong.
I was happy, but maybe less so, with the preceding two paragraphs. I made a rewrite of those that
captures some of what Markus omitted from my version and maybe also is more forceful than either
previous version.
Here is the suggestion: This replaces the text from "Our successful theory of weak interactions ... "
line 25 to "next two decades", line 53. In the new version of the 5-page report that I am about to send you,
this text is pasted in. But, it is still up for debate and revision. Please continue.
Thanks,
Michael
-------------------------------------------------------------------
Our successful theory of weak interactions is based on the idea of an underlying symmetry that is spontaneously broken. The symmetry of the theory of weak interactions dictates the couplings of the quarks and leptons to the $W$ and $Z$ bosons. Its predictions have been confirmed by high-precision experiments. However, this symmetry forbids the quarks, leptons, and vector bosons from having mass. To reconcile the symmetry of weak interactions with the reality of particle masses, one more unexpected element is required. This is a field or set of fields that couple to all types of particles and form a condensate filling the universe. The discovery of the Higgs particle establishes that this condensate exists and is the origin of particle masses.
This is a historic achievement. It is not an end but a beginning. It highlights many questions that the Standard Model leaves unanswered. These require new, equally bold ideas. Two of these questions give particularly strong motivations for collider experiments.
The Standard Model does not explain the underlying structure of the Higgs field or the reason why it condenses. It does not explain the size of the condensate, which sets the mass scale of all known elementary particles. The fact that the observed Higgs particle is a scalar particle makes it very difficult to understand why this scale is smaller than other basic mass scales of nature such as the Planck scale. There are no simple models that answer this question. New fundamental structures are needed. The Higgs field must be a composite of more basic entities, or space-time itself must be extended, through supersymmetry or through extra dimensions of space. These ideas predict a rich spectrum of new elementary particles, typically including a larger set of Higgs bosons, with masses of the order of 1 TeV.
The Standard Model does not account for the dark matter that makes up most of the matter of the universe. The simplest and most compelling model of dark matter is that it is composed of a stable, weakly interacting massive particle (WIMP) that was produced in the hot early universe. To obtain the observed density of dark matter, this model requires the energy scale of WIMP interactions to be roughly 1 TeV. If this model is correct, it may be possible to study dark matter under controlled laboratory conditions in collider experiments.
Thus: \emph{Compelling ideas about fundamental physics predict new particles at the TeV energy scale that should be discoverable in experiments at the LHC and planned future accelerators. These experiments will provide the crucial tests of those ideas. Furthermore, if such particles are discovered, they can be studied in detail in collider experiments to determine their properties and to establish new fundamental laws of nature.}
The past successes of particle physics and its current central questions then call for a three-pronged program of research in collider experiments:
\begin{enumerate}
\item We must study the Higgs boson itself in as much detail as possible, searching for signs of a larger Higgs sector and the effects of new heavy particles.
\item We must search for small deviations in the standard model predictions for the couplings
of the $W$ and $Z$ bosons and the top quark, which are most affected by the physics of mass generation.
\item We must search directly for new particles with TeV masses that can address these important problems in fundamental physics.
\end{enumerate}
The Energy Frontier study pointed to all three of these approaches as motivations for further experiments at colliders. The results of the study confirmed that the existing LHC detectors and their planned upgrades, together with proposed precision lepton collider experiments, will be nimble and sensitive enough to carry this three-fold campaign forward into the next two decades.
--------------------------------------------------------------------
-------------------------------------------------------------------------------------------
Michael E. Peskin [log in to unmask]
HEP Theory Group, MS 81 -------
SLAC National Accelerator Lab. phone: 1-(650)-926-3250
2575 Sand Hill Road fax: 1-(650)-926-2525
Menlo Park, CA 94025 USA www.slac.stanford.edu/~mpeskin/
---------------------------------------------------------------------------------------------
________________________________________
From: Ashutosh Kotwal [[log in to unmask]]
Sent: Friday, October 11, 2013 7:24 PM
To: Raymond Brock
Cc: Sally Dawson; Markus A. Luty; Peskin, Michael E.; snowmass-ef
Subject: Re: [SNOWMASS-EF] EF conveners phone meeting -- minutes and urgent homework
> Here's my suggestion:
>
> Compelling theories of fundamental physics predict new particles at the TeV energy scale which should be discoverable in experiments at LHC and planned future accelerators. Such experiments should be designed to provide the crucial tests of these ideas. Furthermore, if such particles are discovered they can be studied in detail to determine their properties, leading to the establishment of new fundamental laws of nature
>
> best
> Chip
OK with me
Ashutosh
########################################################################
Use REPLY-ALL to reply to list
To unsubscribe from the SNOWMASS-EF list, click the following link:
https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=SNOWMASS-EF&A=1
|
