# Presentation: 841383

## Enlarged pattern bank and upper i.p cut in SVT triggers

- Marco Rescigno – INFN/Roma
- Trigger Upgrade Review
- 7/27/2006

- _Outline_
- Physics opportunities
- Issues
- Plans

## Introduction

- We are here but:
- In principle don’t necessarily need extra hardware to accomplish this single option on its own
- Extra load for fitter should be kept reasonable
- Possible compromises with other needs should be possible
- Apologies: not a great deal of additional studies since May 12th trigger workshop

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## Motivations

- Bs lifetime measurements very interesting:
- non-negligeable decay width difference (s ) expected for Bs mass eigenstate (unlike for Bd)
- Still large experimental uncertainty on a fundamental property of Bs meson !
- Richer phenomenology allows exploring CP violation through lifetime measurement alone (no tagging required!)
- Bs mixing has given the first constraint on the size of possible New Physics contributiong to Bs mixing amplitude, but no contraint on its phase  (s) exists yet  accessible via s
- One possible high-light of the  B-physics program for Run II before LHCb takes over

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## Effect of s

- Bounds on NP contribution to Bs mixing phase

- Current

- s/s)=±0.01

- Similar impact of  direct bs measurement at Tevatron!
- (From Luca Silvestrini’s talk at Elba meeting)

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## s from BsKK  (350 pb-1)

| c(Bd) | 452 | ± | 24  | 460 | ± | 4 |
| --- | --- | --- | --- | --- | --- | --- |
| c(Bs  KK) | 463 | ± | 56 | 458 | ±  | 53 |
| CP/CP |  |  |  | -0.08 | ± | 0.23 |

- c(B**d**)floating     c(B**d**)** **PDG constrained

- s from BsKK  (350 pb-1)

- M.Donega’, S.Giagu

- Use W.A cs=436±12 um

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## s vs s

- All these measurements should converge
- BsKK test theory at loop level as opposed to tree level BsJ/

- BsK+K-

- BsJ/

- BsDsl, Ds

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## c efficiency curve

- c efficiency curve

- Current Two Track Trigger requires:
- 2 SVT track
- Minimum i.p.  100/120 um
- Minimum Lxy 200 um
- Max i.p of 1 mm
- Efficiency drops significantly beyond ~1mm
- Due to both trigger cut and pattern efficiency, can improve now thanks to last year trigger upgrades

- Note Log scale on y axis!

- Can double the effective luminosity by moving the cut to 2 mm: analytical calculation CDF 7359

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## Trigger limitations

- Pattern generated only for tracks originating inside a disk centered around beam-line (32 K pattern limitation in the original AM bank)
- Maximize signal purity at trigger level (fake have wider i.p. distribution)
- Disk radius used to be 1.2 mm, gradually increased to 1.4 mm
- With the 512 K bank there should be pattern space to increase more without comprising too much timing
- We should also be able to sustain an higher L2 accept rate at least at relatively lower lumi where the TTT will be live (and especially on spacialized triggers: BPIPI, PHI triggers)

- P.V.

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## Upper Lifetime Cuts and Stat. Power per Event

- Analytical calculation by Jonas Rademacker (CDF 7359)

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## s from BsKK  (future)

- Key points:
- Mantain trigger yield (B_PIPI)
- Save dE/dx for PID
- Could reach O(3%) accuracy
- Could do it much before and/or reach 2% accuracy with looser max i.p. cut at Level2/3
- Exclude @ >3 new physics phase around 90° in BsKK through lifetime measurement
-  s/s reach comparable or better than J/
- Need better precision on Bs lifetime from flavor specific modes: BsDsl, Ds
- Assumed a 3X improvement over W.A.  12 um  4 um

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## What do we need?

- Goal is increase the trigger cut to ~2 mm (instead of 1 mm): would provide more than double effective luminosity!
- How much does it cost?
- In term of L2 processing time
- Extra pattern firing because of larger super strips
- In term of pattern usage
- How many more patterns do we really need for this application?
- In term of L2 rate
- In term of L3 rate

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## What has been done

- Stefano Torre generated new pattern bank starting from the 128 Kpattern one
- Enlarge beam spot from 1.3 mm  2.5 mm
- Same superstrip as in original the 128 K case
- For 95% coverage 300K pattern has been generated (to be optimized yet)
- Today: some plots on recent data re-run with svtsim and new pattern bank

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## First real data with bigger spot

- 400 K L1 prescaled backup triggers
- Efficiency looks OK : 659K tracks vs 639K tracks in real data
- Behave as expected (increased number of tracks at high i.p.)
- Efficiency for 1.5 mm ip tracks not negligeable also for standard pattern, need new pattern to have decent acceptance at 2 mm
- Don’t probably need to go far out to 3 mm (less extra patterns)

- Run # 211539,211554
- Linst = 180  20 E30 cm-2s-1

- SVT i.p.

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## First real data with bigger spot

- 400 K L1 prescaled backup triggers
- Efficiency looks OK : 659K tracks vs 639K tracks in real data
- Behave as expected (increased number of tracks at high i.p.)
- L2 rate increase linearly with upper i.p. cut (fake dominated background is flat in i.p.)
- Need more data to be quantitative...

- Run # 211539,211554

- min(max(d1,d2))

- Min(max(ip1,ip2))

- Additional rate

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## Estimate of additional rate

- Extra rate at L2
- Limited impact an B_PIPI trigger path (<10%)
- More troublesome on generic B_CHARM (~40%)
- Maybe not a problem because we don’t rely on this trigger path at high lumi anyhow
- Need to check L3 rates
- Expect milder effect, SVT tracks at high i.p. suffer from a higher fake rate than offline tracks

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## Plans and conclusions

- A  summer student from Rome (Sara Borroni) is here in August/September to look at recent data, and refine studies and proposal
- Seems very easy to implement test triggers
- Will continue looking at data:
- Optimize pattern usage together with SVT folks
- Make realistic L2/L3 rate estimate as a function of inst. Lumi.
- Study quality of i.p. measurement by SVT for very displaced tracks
- Produce MC samples to be used by for evaluating resolution improvements (with Mauro Donega’ )
- If no resource-conflicts will be found seems feasible to make lumi to come even more valuable for Bs physics!

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## Backup

## In pursuit of New Physics (with Bs)

- If sin(2) bs anomaly confirmed expect same New Physics  phase to appear also in Bs
- Finding two lifetime components in Bs decays to a CP defined final state (like (J/) 0,//) signal New Physics!
- Bs mass eigenstate  CP eigenstate (Bs mixing phase  0)   (Dunietz,Fleisher,Nierste – 2000)
- Time dependence of  Bs K+K- or CP even component of Bs

- Compare lifetime from to 1/L from Bs J/
- Establish New Physics if different !
- (see U.Nierste Chigago Flavour Seminar: Feb 25th 2005)
- Bssimilar in scope to BsKK lifetime analysis

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## What’s next?

- NP has few corner for NP to hide in B/Flavor physics
- Bs mixing frequency started constraining the last big one...

- Bs mixing phase not constrained by ms !
- Other observables are needed to obtain constraints (Luca Silvestrini’s talk)
- Tevatron is already doing a good job and will do better before LHC takes over !

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## s

- Light and Heavy Bs mass eigenstate expected to have sizeable width difference
- Mass eigenstate coincide with CP eigenstate in SM (no CP violation in mixing)

- Two ways to measure it:
- In decays to CP+,- modes measure L=1/L, H=1/L (e.g.BsKK)
- Or measure L, H in modes with both CP state (BsJ
- CP violation in mixing will result in both Heavy and Light state having a component of both CP states. This result in:

- =

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## Bs decays to VV (BsJ/psi 

- Angular analyis allowsdisentanging the two CP component
- Give eventually access to Bs mixing phase (s) SM ~0 in tagged and _untagged_ (if s big) measurement!
- Untagged measurement are very interesting for CDF!

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## s from BsJ/  (present)

- CDF and D0 similar sensitivity:
- Yield (D0)=1200 ev. /fb-1
- Yield (CDF)=1000 ev. /fb-1 (after c cut, see later)
- Resolution on s scale as N

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## s from BsJ/  (future)

- Key points:
- Mantaining yield of J/
- Good vertexing
- Controlling resolution function tails
- Final resolution expected similar to RUN II early expectations O(0.05)
- Improvement possible:
- Add other modes
- Add further J/ from other triggers (TTT)

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## Direct meausrement of s

- In analogy to sin2 from J/Ks measure time dependent CP asymmetry in BsJ/
- Single amplitude bccs dominate
- CP asymmetry in the interference of mixing and decays measure 2*mixing phase
- Measurement builds on mixing measurement legacy:
- Require resolving mixing oscillation
- Require tagging
- Require statistics...

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## Bs0→J/signal

- From J/PSI trigger path
- S/N ~5
- Cut on Lxy applied

- M.Rescigno - Trigger Upgrade Review July 27th 2006

**Notes:**
after optimization we have both the yeld for the channel and the estimation of the uncertainty on the longitudinal polarization amplitude

## Bs0→J/signal

- Include all two track trigger path
- Prescaled LOWPT +30%
- ~80% of events unique to TTT
- S/N ~3
- Few % contamination from Bd modes

- M.Rescigno - Trigger Upgrade Review July 27th 2006

**Notes:**
after optimization we have both the yeld for the channel and the estimation of the uncertainty on the longitudinal polarization amplitude

## Bs signal

- Same selection as published analysis (Rs) with 180 pb-1)
- Expect 0.10-0.15 error on longitdinal pol. (similar to B-factory first PRL)

- Bs signal

- All trigger paths

- 40 events

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## ACP(mix) from Bs0→J/

- Input from latest ms measurement :
-  c = 86 fs
-  D2 = 0.04/0.05 depending on the sample  (also with “minor” improvement up to 0.07)
- Yield as in the 1st fb-1
- Include extra dilution from disentangling CP state (CDF 6628) using measured CP odd fraction
- 0.18± 0.04   worse resolution by 50%
- Include S/N terms (assumed constant in t)
- Include TTT data + ’
- Not evaluated yet sensitivity to s from interference term in the untagged sample
- D0 claims   sin(s)=0.7 with 1fb-1 in the s/s paper !

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## ACP(mix) from Bs0→J/

- Compare with ACP(mix)th = 0.07± 0.50 (Luca’s Talk)
- Should generate a coherent effort from CDF like it was done for ms
- Have sin2 from J/Ks to break the ice!

- 0.2 precision achievable!

- M.Rescigno - Trigger Upgrade Review July 27th 2006

## Obiettivi e scopo di Sara

- Imparare a conoscere il sistema di trigger di CDF
- Imparare ad utilizzare differenti dataset per stimare il trigger rate  trigger table building
- Utilizzo del fitter di “vita-media” sul MC per stimare miglioramento delle prestazioni
- Partecipare alla review sui trigger upgrade (prima review prevista per il 27 Luglio) e all’elaborazione di una nota di supporto:
- Ottimizzazione larghezza della beam-spot anche in relazione alle altre proposte (e.g. abbassamento soglie in momento trasverso)

- M.Rescigno - Trigger Upgrade Review July 27th 2006