John Jaros HPS Collaboration Meeting at JLAB May 22 2018 What HPS has been doing since last time Readying the 2015 Bump Hunt for publication Finalizing the 2015 Vertex Search ID: 697614
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Slide1
HPS Update
John Jaros HPS Collaboration Meeting at JLAB May 22, 2018Slide2
What HPS has been doing since last time…
Readying the 2015 Bump Hunt for publicationFinalizing the 2015 Vertex SearchPreparing the 2016 Data for AnalysisUpgrading the SVT and Positron TriggerPlanning the HPS Run in 2019
Targeting new physics for HPS
Considering HPS Beyond 20192
HPS UpdateSlide3
Readying the 2015 Bump Hunt for Publication
“And what rough beast, its hour come round at last/ Slouches towards Newport News to be born?”Omar showed first public HPS results at JLAB one year ago.
Getting to final results required…
* Rerunning analysis with TwPass6 * Evaluating Systematics * Completing an Analysis Note * Drafting the first HPS physics publication
3
HPS UpdateSlide4
Evaluating and Correcting Systematics
New Corrections Applied* Mass corrections due ztarget = -5 mm* A’ Radiative Tail (thanks Sebouh)Sources of Systematic Error
* Mass Resolution different in data/MC * Radiative Fraction
* Small biases in the FitsResults
4
HPS Update
Mollers
Scale Mass Resolution
Composition Uncertainty
Pulls vs MassSlide5
Analysis Note
Omar et al. distributed the 2015 Bump Hunt analysis note on 12/18/2017One complication: the new limit is worse than the old one. Why? Can we fix?
5HPS UpdateSlide6
Problems with the Fits
Omar traced the discrepancy to two effects* Corrections in relating limits in 2 to limits from the fit due to A’ radiative tail and new estimates of sample composition
(~30%)* New fits give substantially larger limits
(x 2.5)Omar, Tim, and Matt G addressed problems with the fits
*
New result uses TwP6, which has worse mass resolution than P4.
Worse resolution
wider mass bins larger background uncertainty
* Fix: New parameterization of background gives better fits with fewer
parameters, so reduces background uncertainty
* Bug in
RooFit
identified which made bias look artificially large.
Switched to Minuit. Upper limits now under control.
See Omar’s talk tomorrow for current status.
6
HPS UpdateSlide7
Preparing a Draft Paper
Writing Committee was formed,drafted the bump hunt paper, and distributed it on 03.03.2018.Comments were solicited.Comments have been addressed
(thanks all who helped!)A new draft is ready to incorporate the final results when they are ready.
HPS is very close to submitting its first physics result.
7
HPS UpdateSlide8
Revisiting Procedureshttps://
confluence.slac.stanford.edu/display/hpsg/HPS+Executive+Committee Live and learn. Some changes to present policy. See confluence for the full story.Analysis Note and New Results
* Analysis Note is prerequisite for presenting any new HPS physics results
* New results must be shown to HPS ≥ 1 week before public presentation* New results need EC, PPC, and at least 2/3rds of those voting for approval
Presenting Thesis Results
*
Thesis results are public, so must adhere to rules above.
* Results to be included in a thesis must be presented to HPS for comment at
least 1 week prior to a student’s defense
.
8
HPS Experiment OverviewSlide9
Finalizing the 2015 Vertexing Result
Vertexing problems were identified in Pass6, required Pass7.* Covariance matrix for displaced vertices wrong (fixed by Matt, Miriam)
Other fixes and fixers needed for Pass7* SVT Flags set (thanks, Sebouh)
* ECal steering files updated for calibration (…Holly)* Target z position (…Norman)*
Ecal
alignment revisited (…Nathan)
*
Ecal
time corrections (…Holly)
*
Add beam spot and beam size
9
HPS Experiment Overview
Before AfterSlide10
Reconstruction and Re-Reconstruction
Pass7 incorporated these fixes (thanks Norman and Rafo)* Lots of shepherding and organization needed* Big job: ~20k files, 7-15 hours/file* DB resource issues addressed
* Timeouts and fatal exceptions dealt with
Pass8 (thanks again Rafo)* SVT alignment constants from compact.xml* Re-processed all 0.5 mm 2015 data by mid-January
* Re-processed all 1.5 mm 2015 data by mid March, which
required new detector definition and SVT good flag (Norman,
Sebouh
)
Vertexing
problems solved. Just starting to discover Pass8 “features”.
Will we eventually need Pass9?
* Continuing puzzles: target position, track-
Ecal
match, T/B
Asym
…
* Do we know beam spot position, beam angles,…?
10
HPS Experiment Overview
See talks from Norman,
Miriam, and Bradley
Completed, but wrong SVT alignment constants
were used, so…Slide11
Vertex Progress with Pass8
Holly’s L1L1 Analysis with Pass8 looks promising* Mass vs decay length OK. Minimal high z background events.
* Vertex errors fixed, so V0 projection to target gives better discrimination.
11
HPS Experiment Overview
Old
New
eliminates
more
bkg
eventsSlide12
Vertex Progress with Pass8
Matt S shows some L2L2 backgrounds originate from trident production in L1 dead silicon!Vertexing Studies require more and better MC
* Generated tritrig-
wab-beam with full 2015 statistics at SLAC (Takashi, Jeremy)* Add MC truth to ntuple (Matt S)* Add beam tilt and profiles (Bradley)
* Simulate beam backgrounds more accurately (Bradley)
12
HPS Experiment Overview
y ≥ 0.5mm
z ~ z
L1
p
e+e
~
p
beam
Vertex y [mm]
Vertex z [mm]
P
e+e
-
[GeV/c]
EventsSlide13
New MC for Vertex Analysis
Large MC Sample enables studies of zcut fits (Holly)Large MC Sample will help
diagnose L1L1, L1L2, and L2L2 backgrounds (Matt)
13HPS Update
Coulomb
Scatters?
MC
dataSlide14
Finalizing the 2015 Vertex Search
Lots to hear about on Wednesday:14HPS UpdateSlide15
Sebouh’s thesis has provided a first look at 10% of 2016 Pass1
Preparing for 2016 Data Analysis
15
HPS Update
Data looks OK
Performance similar
to 2015
Limits are roughly as
expectedSlide16
Preparing for 2016 Data Analysis
https://confluence.slac.stanford.edu/display/hpsg/PhysRun2016+Pass2+Checklist16HPS Update
Finishing touches needed for Pass2
See Alessandra’s talkSlide17
Upgrading HPS
The Upgrades are needed to secure HPS Vertex Reach in 2019Positron Trigger Upgrade: Hodoscope* Boosts acceptance* Reduces WAB rate
* Improves trident yieldSVT Upgrade: L0*
Doubles z resolution* Boosts acceptance in z* Huge impact on reach
17
HPS UpdateSlide18
Status of HPS Upgrades
Rafo and Tim have updated EC on designs, progress, and schedule Positron Trigger Upgrade on track for completion Summer 2018* Design reviewed and complete* Scintillator, wavelength shifter fibers, cables, FADCs in hand* PMTs purchased
* Prototype tests in EEL
SVT Upgrade planned completion Jan 2019 * Silicon sensors due Summer 2018* Mechanical designs ready for review* Hybrid design reviewed and completed, in layout
* SVT DAQ Update underway to incorporate RCE improvements
Present status in talks by
Rafo
and Tim after lunch
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HPS UpdateSlide19
HPS Run in 2019“Don’t look back. Something might be gaining on you
.”A+ Physics! The HPS 2019 Run will explore virgin A’ parameter space, well-motivated
by models of light, thermal dark matter.If 2m
> mA’
> m
, then A’
SM visibles
.
HPS Works!
*
Bump hunt is publication quality
* Vertex resolution well-simulated
* L1L1 backgrounds are minimal
Rejection 10
7
: 1
HPS can see something new!
Next Step: 4 PAC weeks at ~4.5 GeV* 8 week run Summer 201919
HPS UpdateSlide20
HPS Run in 2019
Don’t delay! Competition is coming.LHCb*
Already reported A’µ+µ- searches
* More coming from 2017-18 runs* Covers HPS territory in Run 3
(2021-2023) with trigger-less readout
SeaQuest
and CERN
*
SeaQuest
will report soon on its
2017
A’
µ+µ-
test run
*
With proposed
Ecal
trigger,
SeaQuest
covers much of HPS territory (2019?)
* CERN is entering the fray. New proposals (FASER, SHIP, NA62) are under consideration.
20
HPS UpdateSlide21
CERN is Paying Attention
https://indico.cern.ch/event/714087/timetable/https://indico.cern.ch/event/644287/
New Proposals: SHIP, METHUSLA, FASER,
milliQan, Codex-b21
HPS Update
Reports coming end of 2018, may be of interestSlide22
New Physics Targets for HPS
Already on the list* SIMPs (Matt S on Thursday) * True Muonium (Bradley on Thursday)* Dark pions and multi-lepton decays
Translating A’ Limits to searches for other hidden vectors* Searches for dark photons provide constraints on other vector mediators
which couple to B-L, B and L, etc. Ilten, Soreq, MW, Xue [1801.04847]
A General, Data Driven Vertex Search?
*
Prerequisite: high efficiency, multi-particle tracking; recoil e- detection.
* Signatures
Single high impact parameter track, not pointing to material (miss a track)
*Neutral two particle vertex, but include lower ESUM, wider angles
Doubly charged two particle vertex (miss some tracks)
*Multi-track vertices
* Anything unexpected in our data? We should look!
22
HPS UpdateSlide23
HPS 2019 and Beyond
Many analysis possibilities! New Students and Post Docs Needed!* 2015 0.5 + 1.5mm Bump and Vertex* 2016 Bump Hunt* 2016 SIMP SearchMany Service Opportunities!
Ditto!* Continue to improve and refine tracking
* Data storage, processing, and
MC generation
for a huge data set
* Can we be ready to process and
analyze
2019 data
immediately
?
We may need to
be if there is competition.
Getting Ready for
the 2019 Run will be
the centerpiece
of
the next
HPS Collaboration Meeting.
Stepan will discuss running beyond 2019 on Thursday.23HPS UpdateSlide24
Conclusions
HPS is very close to a major milestone: Publishing the 2015 Bump Hunt Result2015 Pass8 Recon, which incorporates many improvements, is letting us finalize the 2015 Vertex Search and ready it for publication.Sebouh’s first look at 2016 data looks promising. With a final alignment, we are ready
to proceed with 2016 Pass2 and more physics analyses.SVT and Positron Trigger Upgrades will guarantee significant reach in 2019
.We need them in time for the run.The 2019 run promises exciting physics, lots of data, and lots of analysis opportunities.
More students and postdocs
needed!
We must publish the results from the remaining 2015 running and from 2016 in timely fashion.
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HPS Update