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HPS Update HPS Update

HPS Update - PowerPoint Presentation

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HPS Update - PPT Presentation

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

update hps data vertex hps update vertex data 2015 analysis results 2019 run 2016 beam physics bump svt ready

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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

18

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.

24

HPS Update