Third installment of my homework: Here are my suggestions for the VLHC
discussion in the 50 page summary report.
Lines 1092-1106: Suggested replacement:
One of the ideas at Snowmass that gained momentum through the week was
renewed interest in a Very Large Hadron Collider (VLHC).
Reinvigorating R&D in a VLHC was a clear recommendation of the New
Particles and Forces Group and the conveners.
The combination of luminosity and energy provides many powerful physics
capabilities:
1. High rates for double Higgs boson production; measurement of triple
Higgs boson couplings to 8$\%$
2. Sensitivity to new Higgs bosons and states associated with extended
Higgs sectors at 1 TeV.
3. Increased reach for new particles associated with naturalness by almost
an order of magnitude in mass over LHC,
including SUSY particles, top partners, and resonances.
Examples: gluino reach to 10 TeV, stop to 5 TeV, Z' to 20 TeV.
This corresponds to two orders of magnitude in probing fine-tuning relative
to current limits.
4. Sensitivity to WIMP dark matter up to TeV masses, possibly covering the
full natural mass range.
5. Any discovery at LHC, dark matter detection, or flavor searches can be
followed up
by more detailed measurements at VLHC, in addition to searches for
higher-mass particles.
Lines 1192-1195:
Suggest adding at the end: The VLHC was called out in particular at
Snowmass for renewed study.
I think this last point at least partly addresses Liantao's recent comment.
Equally important are the places where VLHC is *not* mentioned in the
50-page summary. I believe it is appropriate to briefly mention VLHC reach
in both the SUSY and resonance sections. I think this is important,
especially since we are hearing from some quarters that the VLHC statements
are not backed up. I will send some proposed text shortly.
Markus Luty
============================================
Physics Department
University of California, Davis
One Shields Avenue
Davis, CA 95616
Phone: +1 530 554 1280
Skype: markus_luty
On Fri, Oct 11, 2013 at 10:03 AM, LianTao Wang <[log in to unmask]>wrote:
> I like Markus' write up.
>
> In the summary, what does "planned future accelerators" refer to?
> HL-LHC (ILC?, 100 TeV?) If it also includes 100 TeV (or around
> similar energies), perhaps we should use a world somewhat stronger
> than "potentially", since I think 100 TeV can cover a lot of ground in
> the model space (and significantly more than others).
>
> Liantao
>
> On Fri, Oct 11, 2013 at 12:57 AM, Markus A. Luty
> <[log in to unmask]> wrote:
> > The first installment of my homework: here is my suggestion for what is
> now
> > lines 31-41 of the 5-page summary. It is longer than what is there now,
> but
> > I think these may be the most important lines in the document.
> >
> > The discovery of the Higgs particle establishes that the masses of
> > elementary
> > particles arise dominantly from interactions with the Higgs field that is
> > turned
> > on throughout the universe. We now have for the first time in the
> history of
> > particle physics a theory all of whose ingredients have been
> experimentally
> > verified, and that can be consistently extrapolated to energy scales many
> > orders
> > of magnitude above the energy scale of collider experiments. This
> historic
> > achievement is not an end, but a beginning, because the standard model of
> > particle physics leaves many fundamental questions unanswered. In the
> > tradition
> > of bold theoretical ideas such as the Higgs mechanism (recognized by this
> > years'
> > Nobel prize) particle physicists have proposed compelling ideas that
> address
> > these important questions, and that have their crucial test at the TeV
> > scale:
> >
> > * The fact that the observed Higgs particle is a scalar particle makes it
> > very
> > difficult to understand why its mass scale is smaller than much-larger
> > fundamental mass scales such as the Planck scale. Addressing this problem
> > requires significant additional structure: either supersymmetry (an
> > extension of
> > Einstein's spacetime symmetry), Higgs compositeness, or extra dimensions
> of
> > space. All of these ideas predict a rich spectrum of particles at the TeV
> > mass scale,
> > typically including a larger Higgs sector.
> >
> > * The standard model does not account for the dark matter that makes up
> most
> > of
> > the matter of the universe. A stable particle at the Higgs mass scale
> with
> > weak
> > interactions with ordinary matter (a WIMP) is one of the simplest and
> > compelling
> > theories of dark matter. If dark matter is a WIMP it may be possible to
> > study
> > dark matter under controlled laboratory conditions in collider
> experiments.
> >
> > To summarize: \emph{Compelling ideas about fundamental physics predict
> new
> > particles at the TeV energy scale that are potentially accessible to
> present
> > and
> > planned future accelerators. These experiments are 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.}
> >
> > The past successes of particle physics clearly call for us to continue
> and
> > extend a three-pronged program of research in collider experiments:
> >
> > First, 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.
> >
> > Second, we must search for small deviations in the standard model
> > predictions
> > for the couplings of the Higgs, W, Z, and top quark from new particles.
> >
> > Finally, we must directly search for new particles with TeV masses that
> can
> > address important problems in fundamental physics.
> >
> > Markus Luty
> >
> > ============================================
> > Physics Department
> > University of California, Davis
> > One Shields Avenue
> > Davis, CA 95616
> >
> > Phone: +1 530 554 1280
> > Skype: markus_luty
> >
> >
> >
> > On Thu, Oct 10, 2013 at 1:57 PM, Ashutosh Kotwal <[log in to unmask]>
> > wrote:
> >>
> >> On Oct 10, 2013, at 4:03 PM, "Peskin, Michael E."
> >> <[log in to unmask]> wrote:
> >>
> >> > minutes of the EF phone meeting 10/8
> >> >
> >> > attending: Chip, Michael, Sally, Daniel, LianTao, Ashutosh, Cecilia,
> >> > Reinhard, Markus, Andy White
> >> >
> >> > There are many items in these minutes that all of you need act on more
> >> > or less immediately. Please read these minutes carefully. We summary
> the
> >> > action items at the end.
> >> >
> >> > Our reports are overdue. We would like to send our reports to the
> >> > Snowmass conveners on Tuesday, October 15.
> >> >
> >> > All line numbers refer to the 10-3 versions sent out last Friday.
> >> >
> >> > 1. From the group on the phone, and from the emails that we have
> >> > received, you seem to be happy with the reports that we put together
> except
> >> > for some specific points discussed below. Michael emphasized that,
> if you
> >> > are not happy, you must speak up now. This is best done by sending
> email to
> >> > snowmass-ef. Urgently, please.
> >> >
> >> > 2. Many of the people on the phone were uncomfortable with the
> language
> >> > on likes 40-41 of the short report: "These puzzles imply that new
> particles
> >> > with masses of the order of 1 TeV which resolve these questions will
> be
> >> > found -- and will be accessible to existing and planned accelerators."
> >> > They felt that "imply" was too strong and that the implication of 1
> TeV
> >> > rather than, say, 5 TeV was made in this sentence.
> >>
> >>
> >> what about replacing
> >>
> >> "…masses of the order of 1 TeV"
> >>
> >> by
> >>
> >> "...masses below about 10 TeV"
> >>
> >> just as an example, ATLAS studies have shown sensitivity to KK gluons ->
> >> ttbar in the 5 TeV range
> >>
> >> ------
> >>
> >> as far as the word "imply" goes, it seems to me that "imply" has a
> >> built-in caveat that it is an implication on the basis of a certain
> logic.
> >> In this case, the logic is that nature will avoid too much fine tuning.
> The
> >> 10 TeV number would make the fine tuning about 0.01%
> >> and the logic is that this is very uncomfortable amount of fine tuning
> >>
> >> So, I think we are protected in the legalistic sense if we do use the
> >> word "imply"
> >>
> >> Also, to me, the scale of how "strong" the language is, is no longer set
> >> by the "strength" of "there must be some new physics to explain massive
> >> gauge bosons…" which worked very well for SSC and LHC motivation. I
> don't
> >> think we have to normalize to that any more. I think we have to
> normalize to
> >> the "strongest" language we could use for ANY new physics, in the
> post-Higgs
> >> discovery, post-theta13, post-Planck…etc… world we live in now.
> >>
> >> regards,
> >> Ashutosh
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> >
> >
> >
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