The second installment of my homework: a brief section to be added to the
long EF summary about direct Higgs searches. It is based on section 1.3.1
in our working group report. Higgs folks may want to take a look and see if
they have comments.
Links to figures:
https://dl.dropboxusercontent.com/u/1153967/T1_HZZ_Narrow_300_5sig.pdf
https://dl.dropboxusercontent.com/u/1153967/T2_HZZ_Narrow_300_5sig.pdf
\section{Extended Higgs Sectors}
Additional Higgs bosons are predicted by many well-motivated extensions of
the
Standard Model, including supersymmetry and composite Higgs models,
and study of this possibility is also motivated simply from the need to
fully explore the Higgs sector.
If the 125 GeV Higgs boson mixes with other Higgs bosons, this will affect
its couplings to the other particles of the standard model, which can be
measured
in precision studies of the 125 GeV Higgs.
On the other hand, the additional Higgs bosons can be searched for directly.
The complementarity of these search strategies is illustrated with a search
for additional Higgs bosons in a model with two Higgs doublets,
studied in detail in Ref.~\cite{2HDMwp}.
Fig.~\ref{fig:HZZreach} shows the discovery reach for a 300~GeV Higgs boson
$H$
decaying via $H \to ZZ \to 4\ell$ compared with allowed region from Higgs
coupling measurements at various experimental facilities.
The important parameters for this search are the Higgs mixing angle
$\alpha$ and
the ratio of the Higgs vacuum expectation values $\tan\beta$, and which
Higgs
bosons couple to which quarks and leptons (type I or II).
The line $\cos(\beta - \alpha) = 0$ is the limit where the additional
Higgs particles decouple and the theory looks like the standard model.
Even for type II models (which include supersymmetry) where the Higgs
coupling
measurements are already very constraining, the direct Higgs search probes
significant additional parameter space.
There is roughly a factor of 2 increase in the reach for large $\tan\beta$
in
each step in going from LHC14 to HL-LHC to a 33 TeV collider with
3000~fb${}^{-1}$.
There is also a significant region where the additional Higgs boson makes a
measurable effect on the couplings of the 125 GeV Higgs boson, so combining
this information we can begin to reconstruct the Higgs sector.
Of course the direct Higgs searches lose sensitivity when the new Higgs
bosons
become heavy, and in this region of parameters the Higgs coupling
measurements
provide the best opportunity for probing the Higgs sector.
\begin{figure}
\centering
\includegraphics[width=0.4\linewidth]{NewParticles/figures_9/T1_HZZ_Narrow_300_5sig.pdf}
\includegraphics[width=0.4\linewidth]{NewParticles/figures_9/T2_HZZ_Narrow_300_5sig.pdf}
\caption{$5\sigma$ discovery reach for 300~GeV $H$
decaying via $H \rightarrow ZZ \rightarrow 4\ell$.
The Type I and Type II 2HDM models as shown in the left
and right panels respectively. Dark and the two light yellow regions
are the $5\sigma$ reach by direct searches at LHC14
with 300~fb$^{-1}$, 3000~fb$^{-1}$) and HE-LHC with 3000~fb$^{-1}$
respectively~\cite{2HDMwp}.
The region expected to be allowed at a
95\% CL by complementary precision Higgs coupling measurements, is shown
as dark (light) blue for 300~${\rm fb}^{-1}$~(3000~${\rm
fb}^{-1}$)~\cite{Barger:2013ofa}.
}
\label{fig:HZZreach}
\end{figure}
@article{2HDMwp,
author = "Brownson, Eric and Craig, Nathaniel and Heintz, Ulrich
and Kukartsev, Gena and Narain, Meenakshi and
others",
title = "{Heavy Higgs Scalars at Future Hadron Colliders (A
Snowmass Whitepaper)}",
year = "2013",
eprint = "1308.6334",
archivePrefix = "arXiv",
primaryClass = "hep-ex",
SLACcitation = "%%CITATION = ARXIV:1308.6334;%%",
}
@article{Barger:2013ofa,
author = "Barger, Vernon and Everett, Lisa L. and Logan,
Heather E.
and Shaughnessy, Gabe",
title = "{Scrutinizing h(125) in Two Higgs Doublet Models at
the
LHC, ILC, and Muon Collider}",
year = "2013",
eprint = "1308.0052",
archivePrefix = "arXiv",
primaryClass = "hep-ph",
SLACcitation = "%%CITATION = ARXIV:1308.0052;%%",
}
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 1:03 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.
>
> Michael suggested the minor change:
>
> "These puzzles lead to the expectation that new particles with masses of
> the order of 1 TeV which resolve these questions will be found -- and will
> be accessible to existing or planned accelerators."
>
> This did not seem to resolve the problem, though at least one person on
> the call thought the statement was now too weak.
>
> Here is the assignment:
>
> Go back to line 31 and rewrite the text up through line 41 so that it has
> the correct level of strength. A sentence or, maybe better, a new very
> short paragraph calling out WIMP dark matter should also be added. We
> would like to have your suggestions for this by NOON FRIDAY.
>
> Michael emphasized that whatever appears should be as strong as we are
> comfortable with.
>
> Naturalness is discussed in the long document in section 1.2.2, p.5. The
> people who were uncomfortable with the above were happy with this section.
> Are you?
>
> Any guidance you can give is in pointing out other too-strong statements
> in the documents would be appreciated.
>
> 3. The language used in the conclusions, e.g. line 179 of the short
> document, for the triple Higgs coupling measurement at the HL-LHC was
> considered too strong. "Observation" has a specific connotation (3 sigma)
> which we expect will not be met. However, we agreed that the access to the
> triple Higgs coupling is an important motivation for the HL-LHC. We would
> like to have your suggestions for how to reword this conclusion, in line
> 179 of the short document, and in line 1009 of the long document.
>
> 4. We asked whether the language on the importance of renewed study of
> the VLHC is as strong in these documents as the language in the executive
> summary. Please look especially at lines 1093 and 1192 of the long
> document and the discussion of the VLHC in the discovery stories on p.
> 34-35. If this is not OK with you, suggest a specific change in the
> language.
>
> 5. Finally, please go through the section of your working group in each
> of the documents and confirm that the numbers given are correct and up to
> date. If not, send to Chip and Michael the specific changes needed. (The
> Higgs group has done this in a very thorough way -- Thank you!)
>
> again, action items - send by Friday October 11 !!
>
> 1. If you are not happy with the overall structure and tone of the EF
> summaries, send a complaint to snowmass-ef
> 2. Suggest rewrite of line 31 and following of the short document
> 3. Suggest language concerning the triple Higgs coupling
> 4. Suggest language concerning the VLHC
> 5. Check that the numbers given are consistent with your working group
> report, and send notice of any variance.
>
> Thanks to all -- but, the work is not done.
>
> Michael will send revised versions of the summaries in the next day or so
> -- but, do not wait for these to do the homework requested.
>
>
>
>
> -------------------------------------------------------------------------------------------
> 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/
>
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