Symposium Summary: Where We Are
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Transcript of Symposium Summary: Where We Are
Symposium Summary:Where We Are
Jeffrey A. Appel, Fermilab
IV International Symposium of
LHC Physics and Detectors
Fermilab, May 1-3 2003
“The End of Science”
And now that science – true, pure, empirical science – has ended, what else is there to believe in.
John Horgan
p226, “The End of Science”
Addison-Wesley, 1996
We are here to reaffirm the opposite.
Empirical science is alive and well. Even more, we are at the threshold of a new era, with a new leap beyond the current energy frontier.
Following the excellent presentations on our future at this symposium, it is perhaps worthwhile to pause a moment and consider the most recent leaps of the energy frontiers of previous eras. What do they suggest?
The ISR and the “200 GeV Machine”
What happened when these machines turned on?
Available energy jumped from ~8 GeV with 30 GeV beams to 20-50 GeV of available energy. A new energy frontier opened.
We were surprised, even shocked by how different the world seemed. Almost immediately, we saw the advent of
high- pt events. Backgrounds for many planned
experiments were orders of magnitude larger than expected. More fundamentally, we had (as we now understand it) the effects of the quark substructure of hadrons. And, we started to produce particles essentially undreamed of before – well, dreamed of by only a few foolhardy visionaries.
The Big CERN and Fermilab Hadron Colliders
What happened when these machines turned on?
Available energy jumped from ~30 GeV of available energy to 0.6 and 2 TeV. A much bigger step, this time.
And, we were surprised – maybe not so much by a new energy scale which was predicted (W and Z masses), but by how heavy the top quark is.
We have seen no direct evidence of any of the suggested new particles: sequential W, Z bosons, Higgs, SUSY, nor techni-particles.
We have not seen a break in pt spectra, the onset of a new
level in the hierarchy of matter, any suggestion of something more fundamental than quarks and leptons.
Real, Substantial Progress!It has been very good to see the progress over the past year on the
LHC, and on detectors, software, and physics planning.
Happy that civil construction is going well, and magnets getting better.
Happy to see so many detector components getting into construction.
We have heard about facing real challenges:
Technical – e.g., DMILL, some electronics noise and yield issues,
material budgets, radiation damage effects
Financial – scope changes, additional funding
Schedule – continuous review and adjustments (e.g., test beams)
Happy to see some full system tests, and indications that planning for commissioning is getting serious attention.
Where We Are wrt the LHCBuilding detectors, solving technical and managerial problems.
Building expanded collaborations and new tools to deal with
the new sociology (int. collab., management, GRID).
Expanding physics goals (heavy ion collisions in ATLAS and
CMS, jets in ALICE, B physics everywhere.
“Design/engineering updates [in simulations] lead to
deterioration in performance.”
But, better algorithms; e.g., tracking and tagging, compensate.
Mock data challenge preparations cannot be over-valued, both
for the physics and for the computing environment debugging.
Even more, better motivation will come from the data itself.
Direct calculation of the probability for each eventThe probability depends on all measured momenta of the final state lepton and jetsEach event’s contribution depends on how well it is measuredTo calculate signal and background probabilities the parton differential cross sections are convoluted with the parton distribution functions and the detector resolution .The probabilities are also corrected by the detector, trigger and reconstruction acceptances.
Mt= 180.1 3.6 4.0 GeV preliminary
Improvement in statistical error is equivalent to an factor of 2.4 in the size of the data sample.The relative error in this result is 3%, compare to 2.9% from the previous CDF and DØ combined average for all channels.
New preliminary DZero top quark mass measurement using Run I data
Your Progress is Important to Us.
Your progress is important to us at Fermilab.
First, for our physics program (CMS) and s.c. magnet program.
Mike Witherell noted that only our Tevatron Collider and
neutrino programs are larger here.
Second, for planning of much of the rest of our program as well.
In fact, your progress is important to all of HEP.
However, Concerns of an OutsiderIndustrial scale technology is still new to our community.
Not obvious that accelerator components will stay ahead of the “just in time” schedule.
Some commercial technologies may not last long enough for our development and construction schedules (DMILL, DSM, networking, and computing components, e.g., Objectivity).
More technology decisions than healthy at this stage (CMS pixel size, ATLAS B layer pixel size, CMS ECal electronics, and LHCb HPD/MAP decisions especially).
Common computing approaches to save duplication – just starting
Testing and commissioning times are getting squeezed almost everywhere – already!
A Few Words About the Physics
I will show the most frequently referenced transparencies:
Higgs
SUSY
Heavy Ions
And two personal favorites:
Compositness
Extra Dimensions
All channel plot
Ivor Fleck ATLAS, Early physics reach
Large cross-section for squark and gluino production
SUSY
Decay chain leads to
- high pT jets
- large missing ET
- isolated leptonsDiscovery of SUSY is easy for masses below 2 TeV
Ivor Fleck ATLAS, Early physics reach
ATLAS 5 discovery curves
~ 100 days :
up to 2.3 TeV
~ “10 days” :
up to 2 TeV
~ “ 1 day” :
up to 1.5 TeV
Bulk Particle Production @ RHIC
1. Initial Conditions/Energy Density: > 5 GeV/fm3
2. Thermalization:
3. Hadrochemistry: Tch ~ 180 MeV, B~25MeV
4. Expansion Dynamics: Tth ~ 110 MeV, <T> ~ 0.6c
<fo>~ 10 fm/c, fo~ 0-3
fm/c Consistent Description of Final State
But we’re missing a picture of Dynamical Evolution
Gunther Roland/MIT LHC2003
ALICE Physics Phases of Strongly Interacting Matter
• Exploring the phase diagram of strongly interacting matter
• LHC provides access to the high T, vanishing B QGP phase
Lattice QCD, B = 0Lattice QCD, B = 0
LHCLHC
Christoph Blume, LHC Symposium 2003, May 1-3, Fermi National Accelerator Lab.
Why Heavy Ion Physics at the LHC?
The “missing picture of Dynamical Evolution” may require:
More dynamic range in kinematic variables
Longer time for escaping partons to feel effects of QGP
Larger samples of charm, bottom, and onium
All these should be available at the LHC.
The Physics Landscape: Pb+Pb Collisions SPS->RHIC->LHC
d
Extrapolation of RHIC results favors low values
Russell Betts - UIC
Xdim: Direct Graviton Production Signal
100 fb-1
Jet + missing EtSignals
Significance
Events for high luminosity
100 fb-1, for Etjet > 1 TeV
Bing Zhou Univ. of Mich. 5/2/03
Where We Are – at a Threshold?In many ways, physics has never been more exciting.
We are about to extend the energy frontier by a factor of 7.
We have an excellent model of what we have seen already.
We know that our model is incomplete, and have detailed
predictions which can be tested definitively soon.
We are not at the “end of science,” but hopefully at the threshold of
exciting new science.
What will the new science be? I don’t really know. However,
personally, I expect we will have major surprises. I expect
surprises comparable to those when ISR and Fermilab began.
My Message
In the face of the new energy frontier,
be prepared to read out working detectors,
be prepared for analysis of early, imperfect data,
be prepared for discovery,
be prepared for surprises in signal and backgrounds,
and be prepared to think new thoughts!
Good luck!
Thank You
To the Organizers.
To the Support Staff.
To the Speakers (specially those who responded to my request
for advance word on their presentations).
To All the Participants.