# Presentation: 804612

## Physics at BTeV and LHC-b

- Rob Kutschke
- Fermilab
- February 5, 2004

- Presented at the Aspen Winter Conference on Particle Physics

## Both are forward spectrometers at hadron colliders.
LHCb: LHC at CERN, first data 2007.
BTeV: Tevatron at Fermilab, first data 2009
Beauty and charm physics:
Precision measurements.
Exhaustive searches for new physics.
How does this physics fit into the big picture?
It is part of broad program to address fundamental questions in flavor physics, many of which have been actively discussed at this conference.
Fundamental idea: Separate b and c from backgrounds via their characteristic decay lengths.  
This introduces the least bias.
Do this as early as possible, in the trigger.

- LHCb: LHC at CERN, first data 2007.
- BTeV: Tevatron at Fermilab, first data 2009
- Beauty and charm physics:
- Precision measurements.
- Exhaustive searches for new physics.
- How does this physics fit into the big picture?
- It is part of broad program to address fundamental questions in flavor physics, many of which have been actively discussed at this conference.
- Fundamental idea: Separate b and c from backgrounds via their characteristic decay lengths.
- This introduces the least bias.
- Do this as early as possible, in the trigger.

- Overview of BTeV and LHC-b

- Rob Kutschke, Aspen04

- February 5, 2004

## Why a Hadron Machine?

- Large samples of b quarks are available:
- BTeV: ~2x1011 b-bbar pairs per year .
- LHC-b: ~1x1012 b-bar pairs per year .
- e+e- Y(4S) at L = 1034 cm-2 s-1 yields ~2x108 B’s per year.
- Require L = 1036 cm-2 s-1 to  be competitive.
- Bs , Bc & b-baryons are produced at hadron machines but not at Y(4S) e+e- machines.
- Lots of charm also produced ( also true at e+e- ).

- Rob Kutschke, Aspen04

- February 5, 2004

## Why a Forward Detector?

- 

- ln(tan

- Pythia MC

- BTeV and LHC-b

- Higher momentum
- Longer decay lengths
- Less MCS
- Use decay length to separate from BG.

- High probability for both b hadrons to be in the acceptance.
- Critical for flavor tagging.

- Rob Kutschke, Aspen04

- February 5, 2004

## Accelerator Parameters and Cross-sections

|  | BTeV | LHC-b |
| --- | --- | --- |
| Location | Tevatron, Fermilab | LHC, CERN |
| ECM |  2 TeV | 14 TeV |
| Collisions | p-pbar | p-p |
| (b-bbar)  | 100 b | 500 b |
| (b-bbar)/(visible)† | 1/375 | 1/160 |
| (c-cbar) | 1.0 mb |    3.5 mb |
| (c-cbar)/(visible)† | 1/40 | 1/25 |
| Peak Lumi | 2 x 1032 cm-2 s-1 | 2 x 1032 cm-2 s-1 |
| Integrated Lumi |  2 fb-1 / year | 2 fb-1 / year |
| b-bbar pairs/year  | 2 x 1011 | 10 x 1011 |

- † Using (b-bbar)/(total)=1/500 from BTeV TDR and      (visible)/(total) 0.75 from Tevatron Run II handbook.

- Rob Kutschke, Aspen04

- February 5, 2004

**Notes:**
Add sigma(c cbar)  sigma(c cbar)/sigma tot 
Clean up sigma(tot) vs sigma(inel)
Can I get sigma inel from Harry?
Time between bunch crossings.

See Callot’s talk.  12 million bg interactions/sec
About 3x10^7 beam crosings /sec

## Design Properties of Interaction Regions

|  | BTeV | LHC-b |
| --- | --- | --- |
| Luminous region, x=y | 30 m | 70 m |
| Luminous region, z  | 30 cm |   5.3 cm |
| < visible BG Interactions/crossing> | 4 - 6 † | 0.42 |
| unch spacing | 396 ns † | 25 ns |

- † Luminosity Leveling:
- Initial BTeV design was for 132 ns spacing with a peak lumi of 1.3 x 1032 cm-2 s-1, with <nBG>=2. We now propose to run with a peak lumi =         1.3 x 1032 cm-2 s-1 but to focus the beams more tightly as the run proceeds.  This can maintain the integrated lumi of 2 fb-1 / year but reduce <nBG>.

- BTeV has a longer luminous region and can tolerate more interactions per crossing.

- Rob Kutschke, Aspen04

- February 5, 2004

**Notes:**
Add sigma(c cbar)  sigma(c cbar)/sigma tot 
Clean up sigma(tot) vs sigma(inel)
Can I get sigma inel from Harry?
Time between bunch crossings.

B0 B+ Bs Bbaryon 40/40/10/10  approx

Tradeoff:
  - LHC b –tune lumi to maximize total number of crossings with exactly one b event collision.
          - average of 0.5 int/crossing
     - see egede for details.
  - bug Neville about this – it does not make sense.
  - BTeV – longer IP so live with it.

## Some Detector Design Drivers

- Need DAQ which can handle rates.

- Rob Kutschke, Aspen04

- February 5, 2004

## BTeV

- p

- Toroids

- Rob Kutschke, Aspen04

- February 5, 2004

- Magnet on the IR
- Allows momentum measurement in the trigger.
- Precision vertex detector
- Planar pixel arrays.
- Vertex trigger at Level 1.
- Can trigger on final states with only hadrons.
- PbWO4 Calorimeter
-   and 0 reconstruction.

- Strong Particle ID
- Ring Imaging Cerenkov (RICH) detector.
- Hadron and lepton ID!
- Background rejection.
- Flavor tagging.
- Excellent muon ID system
- Redundant triggering of final states with muons.
- Fast, high capacity DAQ.
- Can record a significant fraction of all B decays.

- Key Design Features of BTeV

- Rob Kutschke, Aspen04

- February 5, 2004

## BTeV Evolution

- Originally 2 arms
- Lost one arm due to funding constraints.
- Present design allows second arm to come back.
- Design bunch crossing was 132 ns
- Now 396 ns – Tevatron staff working on other projects.
- Implies 3 times the pile up for the same luminosity.
- Luminosity leveling a possible solution.
- Studies indicate typical degradations are 10% in yield for the same S/B.
- Retuning of trigger and forward tracking is in progress.

- Rob Kutschke, Aspen04

- February 5, 2004

## LHC-b Evolution since Technical Proposal

-  Reduced
-   material

-  Improved
-   level-1 trigger

- Rob Kutschke, Aspen04

- February 5, 2004

## LHC-b Reoptimization

- Sept. 2003: TDR for a reoptimized detector.
- Reduce material
- Thinner devices and supports
- Remove unneeded tracking and VELO stations.
- Reduce MS and outright loss due to interactions in material.
- Remove magnet shield to allow B field in region of the Trigger Tracker (TT) and RICH 1.
- L1 Tigger:
- Tracks use VELO + TT hits.
- Crude momentum measurement from bend in the fringe field.
- Low momentum tracks, which can have large scattering, do not contaminate the detached track trigger decision.

- Rob Kutschke, Aspen04

- February 5, 2004

## LHC-b is almost  2 x times larger than BTeV in each of  (x,y,z). 

- LHC-b is almost  2 x times larger than BTeV in each of  (x,y,z).

- LHC-b

- BTeV

- Rob Kutschke, Aspen04

- February 5, 2004

## Technology Choices

|  | BTeV | LHCb |
| --- | --- | --- |
| Magnetic field integral | 2.6 T-m (center to end)  | 4 T-m (full length) |
| Vertex Tracker | Pixels | Silicon Strips |
| Downstream Tracker | Si Strip + Straws Tubes | Si Strip + Straw Tubes |
| Particle ID | RICH; 2 Radiators
C5F12, C4F10 | 2 RICH; 3 Radiators
Aerogel; C4F10; CF4 |
| EM Cal | PbWO4 Crystals | Shashlik: Pb-Scint |
| Hadronic Cal | - | Fe + Scintillating tiles  |
| Muon System | Stainless steel prop tubes | MWPC: wire + cathode |
| Angular Acceptance | 10 – 300 mr | 15 – 300 mr |

- Rob Kutschke, Aspen04

- February 5, 2004

## Main Trigger Overview

- Beam crossing 2.5 MHz
- L1: 50 kHz
- Find tracks in pixels.
- Find vertices.
- Cut on impact parameters
- L2: 5 kHz
- Refine tracks in pixels
- Refine vertices
- Cut on impact parameters
- L3: 2.5 to 4 kHz
- Rate depends on event size.
- May use all detector info
- Algorithms TBD.   Goal is to be as open as possible.  Will select some final states but will also accept more.
- Independent di-muon at L1.

- Beam crossing: 40 MHz
- 10 MHz with inelastic interactions
- L0: 1 MHz
- Find clusters in calorimeter
- Find tracks in  system.
- Cut on PT ( 1 to 3 GeV ).
- Reject pile up.
- L1:  40 kHz
- Find tracks using, VELO, TT and L1 info.
- Find primary vertex.
- Cut on and PT and impact parameter of tracks.
- HLT: 200 Hz
- May use all detector info.
- Select final states.
- Algorithms TBD.

- Rob Kutschke, Aspen04

- February 5, 2004

## Flavor Tagging

- Effective tagging efficiency  D2
-    efficiency; D  Dilution  (Nright-Nwrong)/(Nright+Nwrong)
- Methods in order of decreasing dilution:
- Away side Kaon (Reasonably high efficiency).
- Away side muon (Low efficiency).
- Away side electron (Low efficiency).
- Same side tag K (for Bs) and  ( for B0).
- Jet charge  (Large overlap with Away-K and Away-).
- To remove overlaps, BTeV now uses the simplest method:
- Poll methods in order of decreasing dilution.
- Stop when a method gives an answer.
- We will improve this later.
- LHC-b also has an algorithm to combine all information.
- And also expects to improve it.

- Rob Kutschke, Aspen04

- February 5, 2004

## Flavor Tagging (BTeV for Details)

| Tag Type | Bs |  | Bd |  |
| --- | --- | --- | --- | --- |
|  | D2 Ind |      eD2 Cor | D2 Ind | D2 Cor |
| Away Side K | 5.8% | 5.8 | 6.0% | 6.0% |
| Away Side  | 1.3% | 1.3 | 1.2% | 0.8% |
| Same Side K() | 5.7% | 4.5 | 4.8% | 1.4% |
| Jet Charge | 5.4% | 0.4 | 1.8% | 1.0% |
| Total |  | 12.1 |  | 9.2% |
| Nominal BTeV † |  | 13% |  | 10% |
| LHC-b (TDR) † |  | 7% |  | 4% |

- † Extra 1% allows for use of electrons and for optimized use of all information.

- Ind = Independent    Cor = Corellated

- † My average of several decay modes from LHC-b TDR-9, page 104.

- Rob Kutschke, Aspen04

- February 5, 2004

## The 6 CKM Unitarity Triangles

-  &  probably large,  ~0.03,   smaller

- 

- Rob Kutschke, Aspen04

- February 5, 2004

## Removing Ambiguities from 

- Bo  Ko, Ko
- Exploits K0S/K0L interference.
- Equal amplitudes to 
- Low yield:
- For BTeV:
- 1/100 of Ks+-.
- 1700/year (untagged)
- Can determine sign of  with O(100) low background, tagged events.

- tK integrated over tB

- Decay Rate

- For sin(2)=0.7

- Rob Kutschke, Aspen04

- February 5, 2004

## BTeV Measuring A Feasibility Study

- B0 :
- Sensitivity to ACP in one year:  ±0.030
- But penguin pollution!
- Need and  to unpollute. Tough to do!
- B0  
- Dalitz plot analysis (Snyder and Quinn ).
- (next page)

- Sensitive to both sin(2) and cos(2).

- Rob Kutschke, Aspen04

- February 5, 2004

## BTEV Mini MC Study of B0  

| (gen) |  Rres |   Rnon | (recon) |  |
| --- | --- | --- | --- | --- |
|   77.3o |   0.2 |   0.2 |    77.2o |   1.6o |
|   77.3o |   0.4 |     0 |    77.1o |   1.8o |
|   93.0o |   0.2 |    0.2 |    93.3o |   1.9o |
|   93.0o |   0.4 |     0 |    93.3o |   2.1o |
| 111.0o |   0.2 |    0.2 |  111.7o |   3.9o |
| 111.0o |   0.4 |    0.2 |  110.4o |   4.3o |

- Dalitz plot density:
- Synder Quinn matrix element.
- Incoherent BG:  S:BG = 4:1.
- Non-resonant (flat).
- Resonant in .
- Acceptance and smearing parameterized from Geant based study.
- Results for trials of 1000 signal events + BG.
- Sensitivity to  < 4o, for 1.4 years of running.

- Rob Kutschke, Aspen04

- February 5, 2004

## Summary of CKM Physics Reach (107 s)

| Reaction | Para-meter | LHC |  |  | BTeV |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  |  | Yield | S/B | Sensitivity† | Yield | S/B | Sensitivity† |
| Bo+- | Asym | 26,000 | >1.4 |  | 14,600 | 3 | 0.030 |
| BoJ/KS  ,
 J/l+ l- | sin( | 241,000 | 1.2 | 0.02 | 168,000 | 10 | 0.017 |
| Bs Ds K- | 
 | 5,400 | >1 | 14o | 7,500 | 7 | 8o |
| Bs Ds- | xS | 80,000 | 3 | <100† | 59,000 | 3 | <75† |

- † Sensitivity means either the error on the parameter or the limiting value which we can measure.

- Warning: I have not checked that both made same assumptions about branching fractions.

- † Upper limit for a measurement with 5  significance.  (xS) <0.02 for most xS.

- Rob Kutschke, Aspen04

- February 5, 2004

## Summary of CKM Physics Reach (107 s)

| Reaction | Para-meter | LHC |  |  | BTeV |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  |  | Yield | S/B | Sensitivity† | Yield | S/B | Sensitivity† |
| B-Do (K+-) K- |  |  |  |  | 170 | 1 | 13o |
| B-Do (K+K-) K- |  |  |  |  | 1,000 | >10 |  |
| B0 D0(K)K*0 |  | 3,400 | >2.0 |  |  |  |  |
| B0 D0CPbar K*0
B0 D0CP K*0bar |  | 590 | >0.35 | 7o  to 9o depending on  |  |  |  |
| B-KS - |  |  |  |  | 4,600 | 1 | < 4o + theory errors |
| BoK+- |  |  |  |  | 62,100 | 20 |  |

- † Sensitivity means either the error on the parameter or the limiting value which we can measure.

- Warning: I have not checked that both made same assumptions about branching fractions.

- Rob Kutschke, Aspen04

- February 5, 2004

## Summary of CKM Physics Reach (107 s) 

| Reaction | Para-meter | LHC |  |  | BTeV |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  |  | Yield | S/B | Sensitivity† | Yield | S/B | Sensitivity† |
| Bo+- |  | 4,400 | 0.14 |  | 5,400 | 4.1 | ~4o
(For 1.4 years ) |
| Booo |  |  |  |  | 780 | 0.3 |  |
| BsJ/
 J/l+ l- | sin
 | 7,000 | >0.2 |  | 2,800 | 15 | 0.024 |
| BsJ/,
 J/l+ l- |  |  |  |  | 9,800 | 30 |  |
| BsJ/ | sin | 120,000 |  | 0.06†  |  |  |  |
| BsJ/ | SS |  |  | 0.02†  |  |  |  |

- † Sensitivity means either the error on the parameter or the limiting value which we can measure.

- † Typical values.  Exact values depend on assumptions about xS, , SS and RT.

- Warning: I have not checked that both made same assumptions about branching fractions.

- Rob Kutschke, Aspen04

- February 5, 2004

## Physics Beyond the Standard Model

- New Physics (NP) effects can be subtle:
- More than just:   180o.
- Suppose there is NP in B0 mixing:
- If we measure  and  via mixing mediated modes, J/K0S and , we may measure:
-  
-  
- And measure  via a non mixing method.
-   = 180o
- The triangle closure test misses this sort of NP.
- We need to be careful when we do this!

- Rob Kutschke, Aspen04

- February 5, 2004

## Generic Tests for New Physics

- Specific decays, non-specific models
*B****K*+- & *B****K**+-: can observe NP in distribution of M(+-) and Dalitz plot is sensitive to subtle interference effects.   See hep-ph/9408382.
- Check for inconsistencies in SM without reference to a particular model.

| Reaction | B(10-6) | Yield/year | S/B |
| --- | --- | --- | --- |
| BK* | 1.5 | 2530 | 11 |
| BK | 0.4 | 1470 | 3.2 |
| bs  | 5.7 | 4140 | 0.13 |

- LHC-b
- Yield=8200
- S/B>1

**BTeV**

- LHC-b TDR adjusted for BR in table.

- Rob Kutschke, Aspen04

- February 5, 2004

## Critical Checks on NP using 

- Silva & Wolfenstein (hep-ph/9610208), (Aleksan, Kayser & London):
- Measure using BsJ/  
- Can also use J/but need a complicated angular analysis.
- The critical check is:
- Very sensitive since 0.2205±0.0018
- Since ~ 0.03, need lots of data.
- BTeV: Sensitivity to sin(2 for one year of running: ±0.024.

- Rob Kutschke, Aspen04

- February 5, 2004

## SM mixing and CP violation are small
Lots of room for NP between current limits and SM.
BTeV estimates 
Benchmark: Reconstructed D0 K-+ > 108 /year
Projected sensitivity to ACP ~10-3 in one year for background free D+K*0 K+ or D+K+ / .
LHC-b
Rate of c out of trigger is about equal to rate of b.
I have not seen LHC-b estimates of charm physics but my opinion is that they will do well.

- Lots of room for NP between current limits and SM.
- BTeV estimates
- Benchmark: Reconstructed D0 K-+ > 108 /year
- Projected sensitivity to ACP ~10-3 in one year for background free D+K*0 K+ or D+K+ / .
- LHC-b
- Rate of c out of trigger is about equal to rate of b.
- I have not seen LHC-b estimates of charm physics but my opinion is that they will do well.

- What About Charm?

- Rob Kutschke, Aspen04

- February 5, 2004

## A Brief Look at the Competition

- BaBar and Belle
- No Bs , Bc & b-baryons.
- Need luminosity of O(1036 cm-2 s-1) to compete on all fronts.
- A long way to go from today’s spectacular performance.
- Some important modes may only be accessible in the simple and clean environment of the (4S).
- CDF and D0
- Poorer particle ID
- More constrained trigger and data rates.
- All of the above will do a lot before LHC-b and BTeV enter the game.
- ATLAS and CMS
- Lepton only triggers (no detached vertex trigger).
- Poorer hadron ID.
- Will be very strong modes with di-leptons.

- Rob Kutschke, Aspen04

- February 5, 2004

## Hot Off the Press !

- BTeV is in the President’s budget request for FY05.
- _[http://www.](http://www.cfo.doe.gov/OSbudget/content/science/sciencea.pdf)__[cfo](http://www.cfo.doe.gov/OSbudget/content/science/sciencea.pdf)__[.doe.](http://www.cfo.doe.gov/OSbudget/content/science/sciencea.pdf)__[gov](http://www.cfo.doe.gov/OSbudget/content/science/sciencea.pdf)__[/budget/05budget/content/science/](http://www.cfo.doe.gov/OSbudget/content/science/sciencea.pdf)__[sciencea](http://www.cfo.doe.gov/OSbudget/content/science/sciencea.pdf)__[.](http://www.cfo.doe.gov/OSbudget/content/science/sciencea.pdf)__[pdf ](http://www.cfo.doe.gov/OSbudget/content/science/sciencea.pdf)_
- Request M$10.25 for R&D and engineering in FY05.
- Budget language anticipates construction funding to start FY06 and construction completion in FY09.

- Rob Kutschke, Aspen04

- February 5, 2004

## Summary and Conclusions

- LHC-b well on the way towards first data in 2007.
- Many components already at CERN.
- Can do great physics with “day 1” luminosity from LHC-b.
- Will have head start over BTeV.
- BTeV expects first real funding in October 2004 and first data in 2009.
- R&D is already well advanced.  Final funding decisions this year.
- How to make up for the late start.
- More open trigger and better ECal will allow BTeV to catch up on many modes.
- Working Tevatron allows staged installation and commissioning.
- Both experiments will have the sensitivity to extend both the precision frontier and the rare decay frontier of heavy flavor physics.

- Rob Kutschke, Aspen04

- February 5, 2004

## Where to Find Out More

- BTeV
- Home page: _[http://www-](http://www-btev.fnal.gov/)__[btev](http://www-btev.fnal.gov/)__[.](http://www-btev.fnal.gov/)__[fnal](http://www-btev.fnal.gov/)__[.](http://www-btev.fnal.gov/)__[gov](http://www-btev.fnal.gov/)_
- Click on _[BTeV For Physicists](http://www-btev.fnal.gov/public/hep/index.shtml)_.
- DocDb: _[The BTeV Document Database](http://www-btev.fnal.gov/cgi-bin/public/DocDB/DocumentDatabase)_
- TDRs etc: _[Proposal & TDR describe the experiment & physics](http://www-btev.fnal.gov/public/hep/general/proposal/index.shtml)_
- LHC-b
- Home Page: _[http://](http://lhcb.web.cern.ch/)__[lhcb](http://lhcb.web.cern.ch/)__[.web.](http://lhcb.web.cern.ch/)__[cern](http://lhcb.web.cern.ch/)__[.](http://lhcb.web.cern.ch/)__[ch](http://lhcb.web.cern.ch/)_
- Publications: _[http://](http://lhcb-doc.web.cern.ch/lhcb-doc)__[lhcb](http://lhcb-doc.web.cern.ch/lhcb-doc)__[-doc.web.](http://lhcb-doc.web.cern.ch/lhcb-doc)__[cern](http://lhcb-doc.web.cern.ch/lhcb-doc)__[.](http://lhcb-doc.web.cern.ch/lhcb-doc)__[ch](http://lhcb-doc.web.cern.ch/lhcb-doc)__[/](http://lhcb-doc.web.cern.ch/lhcb-doc)__[lhcb](http://lhcb-doc.web.cern.ch/lhcb-doc)__[-doc/](http://lhcb-doc.web.cern.ch/lhcb-doc)_
- Includes TDR’s, recent talks ...
- Plug:
- BTeV is looking for more collaborators.
-  _[http://www-btev.fnal.gov/public/hep/general/joining/index.shtml](http://www-btev.fnal.gov/public/hep/general/joining/index.shtml)_

- Rob Kutschke, Aspen04

- February 5, 2004