Dear Colleagues,
Please find below the plans for the Colloquia in Minnesota that I had sent
to the other Frontier conveners. I thought that the right protocol was to
discuss this with them and carve up responsibilities before bringing this
to you. Apparently, the Cosmic and Intensity Frontier conveners delegated
this to their working group conveners.
So, here is the email that I sent them. It is a first-draft plan that needs
substantial revision. Your suggestions will be gratefully accepted.
Especially, if you would like to give talks in one of these Colloquia, or if you
know especially good speakers to answer the questions, please let me know.
In general, please keep Chip and me in the loop if you discuss the organization
of these colloquia with people from other frontiers. Chip and I will also be
back to you as we refine the plans for the Colloquia that are mainly about
energy frontier.
Thanks,
Michael
-________________________________________
From: Peskin, Michael E.
Sent: Saturday, June 29, 2013 3:22 PM
To: Peskin, Michael E.
Cc: Hewett, JoAnne L.; [log in to unmask]; [log in to unmask]; [log in to unmask]; [log in to unmask]
Subject: proposed detailed plan for the Snowmass Colloquia
Dear Colleagues:
We have scheduled Colloquia for the Snowmass in Minnesota meeting. I think that it is our job to agree on and publicize detailed plans for these Colloquia, and to invite the speakers. I am beginning with the "gang of 6", but we must also talk with Bill Barletta and the Computing and Instrumentation people.
In this note, I begin a proposal for an outline for each of these colloquia. The general structure that I imagine is:
3 pedagogical talks (20 minutes each)
4 "tough questions" (each answered by 1 speaker, 15 minutes each)
This will leave time for general discussion.
In the cases where the subject overlaps Energy Frontier, I think I know what I am doing. In other cases, I have left some large blanks. But I hope that this will be a reasonable starting point for us to build a complete set of outlines.
There is no time for all of the "tough questions". I have made a choice. Do you agree?
I look forward to your revisions of this set of outlines.
thanks for listening,
Michael
----------------------------------------------------------------
The Colloquia are:
Monday: Dark matter
Tuesday: Higgs boson, Higgs sector, and naturalness
Wednesday: Neutrino mass, mixing, and grand unification
Thursday: Precision frontier: finding new physics through loops and radiative
corrections
Thursday: Cosmic survey: dark energy, inflation, neutrinos, etc.
Friday: High energy cosmic particles
Friday: Energies beyond LHC: Physics goals and technologies
Saturday: Lepton and quark flavor and CP and weakly coupled particles
Sunday: Intensities beyond the planned era
Sunday: Transformative technologies for instrumentation and data
Here are my (first draft) outlines in turn:
------------------------------------------------------------------------------
Dark matter
pedagogical talks:
Models of the dark matter particle
Direct and indirect detection of dark matter
Limits on dark matter particles from colliders
"Tough questions"
What would it take to convince ourselves that
we have made a discovery of dark matter in
direct or indirect detection? What would
it take to convince ourselves that this
particle is responsible for only a part
of the dark matter?
If the dark matter particle is detector through
non-collider experiments, what can we learn
about its properties. Can we learn its spin
and quantum numbers?
If dark matter has no SM interactions stronger
than gravitational, are there any prospects
for discovering its particle nature?
It has turned out that missing transverse energy
is a very effective signature for discovery
at the LHC. So, have we ruled out WIMP dark
matter with mass below 500 GeV?
---------------------------------------------------------------------
Higgs boson, Higgs sector, and naturalness
pedagogical talks:
Properties of the Higgs boson, and methods to
measure the Higgs boson couplings
Strategies to discover additional particles of
the Higgs sector
Models of new physics at the TeV scale associated
with electroweak symmetry breaking
"Tough questions"
The strongest argument for new particles at the TeV scale is that they are
needed to provide a "natural" explanation of electroweak symmetry breaking.
But many of these proposed particles are strongly excluded by LHC and flavor
constraints. Have we excluded "naturalness"? Is there a goal, in terms of
an accelerator energy, for example, to exclude "naturalness"?
In order for the 125 GeV Higgs to be _the_ Higgs it has to account for
Yukawa mass couplings across the spectrum of Fermions. What are the prospects
for measuring the Yukawa couplings to fermions? How much improvement comes
with the HL LHC?
What are the goals for the measurement of Higgs couplings? Is it important
to search for deviations from the Standard Model at 5% level? At the 1% level?
How low is relevant?
The message from the LHC seems to be that with data in hand, we
consistently outperform expectations for extraction of Higgs properties.
How much is there really for an ILC to contribute? What key assumptions
are we making now that we could relax with ILC inputs?
-----------------------------------------------------------------------
Neutrino mass, mixing, and grand unification
pedagogical talks:
Future measurements of neutrino masses and mixings
Models of quark and neutrino mixing angles, and how to test them
Observable predictions of grand unification
"Tough questions"
The measurements of the quark mixing angles have taught us little
in terms of fundamental physics. Do we expect to learn more
from the values of the neutrino mixing angles?
Imagine that we measure the CP violating phase in the neutrino
mass matrix to be 85 degrees (for example). What does this
imply for the hypothesis that the matter-antimatter asymmetry
is due to leptogenesis? What further data would we need to
clarify this relation?
If there are sleptons with mass below 1 TeV, can their masses
or decays be sensitive to the PMNS mixing angles? What new
information relevant to neutrinos would come from the study
of these particles?
With a grand unification scale at 10^16 GeV as predicted by
SUSY-GUTS, the lifetime of the proton is naively expected to
be below 10^33 yr. What are we testing as we push this
limit to 10^35 yr? Is the sensitivity to these parameters
quartic, as for m_GUT, or, more optimistically, quadratic?
If the first and second generation squarks are very heavy,
does this increase the expectation for the proton lifetime?
-------------------------------------------------------------------------
Thursday: Precision frontier: finding new physics through loops and radiative
corrections
pedagogical talks:
the future of precision electroweak: can we get the next decimal
place in mW and sin2theta, and what will we learn?
precision top physics
what do we learn from precision tests of fundamental symmetries
in atoms and nuclei
"Tough questions"
Give specific examples of anomalies in precision
measurements that, if verified, point to a definite target
energy for a future high-energy accelerator.
How much do we learn from measurements of the 3- and 4-gauge
boson couplings? Do these searches compete with direct
new particle searches?
Can the MSbar top quark mass be measured to better than 1 GeV at a
hadron collider? Do we need better accuracy?
Improvements in the muon g-2 meausurement need to be accompanied with
improvements in the Standard Model prediction for the term involving the
hadronic vacuum polarization. What are the prospects for improvement
of the current estimate? To reach the parts per billion level in
the error, the contribution from light-by-light scattering must also
be improved with input from low-energy data. How can this be done?
Thursday: Cosmic survey: dark energy, inflation, neutrinos, etc.
pedagogical talks:
How do we derive the primordial initial conditions from
measurements of cosmic structure?
What astrophysical issues come up in comparing CMB and large-scale
survey measurements? Are the uncertainties under control?
What is the evidence for inflation as the origin of cosmic
structure? Is inflation uniquely preferred as a model?
"Tough questions"
Proponents of the study of cosmic structure claim to measure
neutrino masses more accurately and to lower values
than in long-baseline experiments. Is this really
correct? What assumptions are needed?
A major goal of CMB studies is to improve the search for
the gravity wave component of the CMB fluctuations by
two orders of magnitude. But the observable depends
on the inflation scale to the fourth power.
Is this improvement significant for the theory
of inflation?
For a long time, measurements of primordial element
abundances have suggested that the number of
"neutrinos" or other light species is greater
than 3. What would it take to confirm that this
number is greater than 3.5, or that 3.5 is an
upper bound?
Friday: High energy cosmic particles
I leave this to Cosmic to fill in
Friday: Energies beyond LHC: Physics goals and technologies
(Bill Barletta, Chip, and I have agreed on a program; here it is:)
pedagogical talks:
Physics goals of experiments at energies beyond LHC
(what are the goals? how much energy is sufficient? what luminosity
is required? )
Technology of 30-100 TeV pp colliders
(basic challenges of magnets, tunnel, beam dynamics, radiation)
Technology of 3-10 TeV lepton colliders
(introduction to 2-beam e+e-, muon collider, ultra-high gradient e+e-)
"Tough questions"
Can we really design a detector to measure physics events at 100 TeV and
luminosities of 10^35 and above? Isn't this likely to be the limiting
factor for high energy pp machines?
We do not know how to create superconducting magnets at industrial scale
with fields above about 16 T. Is any solution on the horizon?
Muon colliders have been promised for many years but muon cooling still has
not delivered more than 10% phase space reduction. A muon collider
needs phase space reduction by 10^6. What is the path to get there?
Exotic acceleration mechanisms for electrons have been demonstrated to give
accelerations of GeV/m and even tens of GeV/m. But these devices
operate with low efficiency both in power use and in throughput of
particles. Is there a path to an accelerator based on these technologies
that will deliver high luminosity and TeV energies?
Saturday: Lepton and quark flavor and CP and weakly coupled particles
(I am not sure why "weakly coupled particles" is here. There is
plenty to talk about without this topic. I ignore it below.
Please correct.)
Models of new physics with new flavor mixing; relation of models
to effective operators
Next-generation experiments on quark flavor and CP
Next-generation experiments on lepton flavor and CP
I think that we have already essentially promised to invite Ruth van der Water
to talk about the lattice gauge theory role in this program. This is a great
idea, but does it fit in as a fourth talk in this session?
"Tough questions"
Describe the increase in sensitivity to new particles in loops as a
function of time for the g-2, mu-e conversion, tau -> ell gamma,
and EDM experiments. There should be separate estimates for SUSY models,
in which the flavor-changing effects come from loops, and from models in
which the flavor-change comes from a tree-level effective operator. This
will facilitate plotting this evolution along with the evolution in
sensitivity predicted for direct searches for new particles at the LHC.
Describe the increase in sensitivity to new particles in loops as a function
of time coming from improved measurements of b->s gamma, B and
Bs -> mu mu, and related observables. There should be separate
estimates for SUSY models, in which the flavor-changing effects come
from loops, and from models in which the flavor-change comes from a
tree-level effective operator. This will facilitate plotting this
evolution along with the evolution in sensitivity predicted for
direct searches for new particles at the LHC.
What is the impact of higher precision measurements processes that
determine the CKM angles, such as sin 2beta, sin 2 beta_s, and V_{ub}.
Is it realistic that tensions between these parameters can be sufficiently
strong to signal the presence of new physics?
Give specific examples of anomalies in flavor or CP
measurements that, if verified, point to a definite target
energy for a future high-energy accelerator.
Sunday: Intensities beyond the planned era
I do not know how to fill in this box. However, we have to do it (in consultation with
Bill Barletta) or else Bob Berstein will fill it in for us.
To my mind, the major physics questions are already dealt with under Lepton and Quark
Flavor and CP.
Sunday: Transformative technologies for instrumentation and data
I leave this to instrumentation and computing to fill in. I remind
you that Energy Frontier asked the following questions. Obviously, not
all can be addressed in this session. We should partition these between
this session (general interest) and the EF/InstF joint session on Thursday
morning (specific EF issues).
EF-InstF: High luminosity running at a hadron collider will depend on efficient triggering in a difficult environment. Isolation requirements will likely be compromised, and, as a result, triggering on leptons may need to depend heavily on tracking. What are the most promising enabling technologies for electron/photon/tau triggers in this environment, considering luminosities up to 10^{35} cm^{-2}s^{-1}? What are likely R&D paths to realizing these technologies?
EF-InstF: In the context of proposals of large tunnels that could host both pp and e+e- colliders, it is interesting to ask whether it is possible to design 4 pi detectors that can be used both for pp and e+e- experiments (perhaps with some interchangable inner tracking layers). Is there an optimal design of such a multi-purpose detector? What are the most important compromises required?
EF-InstF: In a hadron collider environment, the ability to recognized displaced vertices and to trigger on them at level 1 would be a transformative technology. Can this be realized?
EF-InstF: In some studies for ILC and CLIC, the sophistication of particle flow calorimetry approaches the ability to resolve single hadrons. At what point does the evolution of particle flow calorimetry give a qualitative, rather than just a quantitative, boost to experimental capabilities? Can we realistically reach this point?
EF-Computing: To what extent is high-energy physics still generating the world's largest randomly-accessed databases? Can we claim to be a world leader in data science? Along what dimensions?
EF-Computing: The Grid was commissioned along with the LHC detectors. ESnet traffic has increased 10x every four years throughout the LHC lifetime. Will improvements in networking infrastructure, QoS, monitoring, etc continue to keep up with LHC demands for distributed computing? In what directions are new enabling technologies required and when must they mature to again keep up with the LHC machine and detector upgrades?
EF-Computing: How do the different physics frontiers--and associated theory and physics simulation--differ in their needs for future computing technology evolution. In what respects can they benefit from common computing technology evolution?
EF-Computing: Proposed very high statistics experiments at the Z resonance require large rates -- many kHz -- at which data is written to storage. What are the limits?
-------------------------------------------------------------------------------------------
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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