# Presentation: 945552

## BTeV Physics Reach

- Ohio State

**BTeV Physics Reach**
**LHC 2003 Symposium**
**K. Honscheid**
**Ohio State University**

## B Physics Today

- CKM Picture okay
- CP Violation observed
- No conflict with SM

|  | Vud | Vus | Vub |
| --- | --- | --- | --- |
| VCKM = | Vcd | Vcs | Vcb |
|  | Vtd | Vts | Vtb |

- sin(2) = 0.734 +/- 0.054

## Surprising B Physics

| Year | Item | Theory Prediction |  ~Value |  # B’s |
| --- | --- | --- | --- | --- |
| 1983 | b | Too small to be observed ~ < 0.1ps | 1 ps | 2x104 |
| 1987 | Bo-Bo mixing | Too small to see (~ < 1%) as mtop is believed to be ~30 GeV | 20% | 2x105 |
| 2001 | sin(2) | No direct prediction, but consistent with other measurements | 3/4 | 107 |
|  |  |  |  |  |

- >1011 b hadrons
- (including Bs)

## B Physics at Hadron Colliders

- The Tevatron as b (and c) source
- b cross section 	~100 b, c cross section ~1000 b
- b fraction		2x10-3
- Inst. Luminosity	2x1032
- Bunch spacing	132 ns (396 ns)
- Int./crossing	<2> (<6>)
- Luminous region	z = 30 cm
- Forward Geometry

**2x10****11**** b pairs/year**

- b production angle

- b production angle

- 

## The BTeV Detector

## Efficiencies and Tagging

- For a requirement of at least 2 tracks detached by more than  6, we trigger on only 1% of the beam crossings and achieve the following trigger efficiencies for these states (<2> int. per crossing):
-   efficiency; D  Dilution or (Nright-Nwrong)/(Nright+Nwrong)
- Effective tagging efficiency  D2
- Extensive study for BTeV uses
- Opposite sign K±
- Jet Charge
- Same side ± (for Bo) or K± for (Bs)
- Leptons
- Conclusion: D2 (Bo) = 0.10, D2 (Bs) = 0.13, difference due to same side tagging

**Notes:**
B->pipi efficiency = 0.04 (reconstruction) x 0.82 (PID) x 0.55 (L1+L2) = 1.8%

## The Physics Goals

- There is New Physics out there:
- Baryon Asymmetry of Universe & by Dark Matter
- Hierarchy problem
- Plethora of fundamental parameters
- ...
- BTeV is in a unique position to:
- Perform precision measurements of  CKM Elements withsmall model dependence.
- Search for New Physics via CP phases
- Search for New Physics via Rare Decays
- Help interpret new results found elsewhere (LHC, neutrinos)
- Complete a broad program in heavy flavor physics
- Weak decay processes, B’s, polarization, Dalitz plots, QCD...
- Semileptonic decays including b
- b & c quark Production
- Structure: B baryon states
- Bc decays

## Part 1: Is the CKM Picture correct?

**Part 1: Is the CKM Picture correct?**

- Use different sets of measurements to define apex of triangle
*    **(adopted from Peskin)*
- Also have K (CP in KL system)

*Magnitudes*

*B**d** mixing phase*

*B**s** mixing phase*

- Can also measure via B-DoK-

## Measuring Using Bo  

- A Dalitz Plot analysis gives **both** sin(2) and cos(2)(Snyder & Quinn)
- Measured branching ratios are:
- (B = ~10-5
- (B +  = ~3x10-5
- (B <0.5x10-5
- Snyder & Quinn showed that 1000-2000 tagged events are sufficient
- Not easy to measure
- 0 reconstruction
- Not easy to analyze
- 9 parameter likelihood fit

- Slow 0’s

- Nearly empty
- ( polarization)

- Dalitz Plot for Bo

## Yields for Bo

**Yields for B****o******

- Based 9.9x106 background events
- Bo+-    5400 events, S/B = 4.1
- Booo  780 events, S/B = 0.3

- 

- 

- o

- Background

- Signal

- mB (GeV)

- mB (GeV)

- Booo

**Notes:**
Get updated plots, to have better S/B numbers

## Our Estimate of Accuracy on 

**Our Estimate of Accuracy on ******

- Geant simulation of Bo(for 1.4x107 s)

- Example:
- 1000 Bo signal + backgrounds
- With input =77.3o

| (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 |

## Bs Mixing (Vtd/Vts)

- BTeV reaches sensitivity to xs of 80 in 3.2 years

## Measuring 

- In the SM the phases and magnitudes are correlated:
- |Vus| = 0.2205±0.0018
-  is the phase of Vts -> Bs Mixing
- Good: Bs->J/ plus non-trivial angular analysis
- Better: Bs -> CP eigenstate such asBsJ/  

- Silva & Wolfenstein (hep-ph/9610208)Aleksan, Kayser & London

## Measuring II

- BTeV can reconstruct  and ’
- Yield in one year
- BsJ/2,800 events  with S/B = 15
- BsJ/9,800 events  with S/B = 30
- Error on sin(2 = 0.024
- With  ~ 2o a precision measurement will require a few years.

## Physics Reach (CKM) in 107 s

|      Reaction |   B(B)   (x10-6) | # of Events | S/B |    Parameter | Error or          (Value) |
| --- | --- | --- | --- | --- | --- |
| Bs Ds K- |      300 |       7500 |    7 |       -  |          8o |
| Bs Ds- |    3000 |    59,000 |    3 |          xs |         (75) |
| BoJ/KS   J/+ - |      445 |  168,000 |  10 |      sin(2) |       0.017 |
| BoJ/Ko, Ko    |         7 |         250 |   2.3 |      cos(2) |        ~0.5 |
| B-Do (K+-) K- |       0.17 |         170 |    1 |  |           |
| B-Do (K+K-) K- |        1.1 |      1,000 | >10 |        |          13o |
| BsJ/ |     330 |      2,800 |   15 |  |  |
| BsJ/ |     670 |      9,800 |   30 |     sin(2 |        0.024 |
| Bo+- |       28 |      5,400 |  4.1 |  |  |
| Booo |         5 |         780 |  0.3 |  |          ~4o |

|  Reaction |  B(B)(x10-6) | # of Events | S/B |   Parameter |       Error |
| --- | --- | --- | --- | --- | --- |
| B-KS - |       12.1 |      4,600 |     1 |  | <4o + |
| BoK+- |       18.8 |    62,100 |   20 |        | Theory err.       |
| Bo+- |       4.5 |    14,600 |    3 | Asymmetry |       0.030 |
| BoK+ K- |        17 |    18,900 |   6.6 | Asymmetry |       0.020 |

**Notes:**
Point out that there are several ways to measure , so can resolve ambiguities; other ways of resolving ambiguities in beta.
Error estimate on alpha is a guess. Can do better on chi by using electron modes. 

## Part II: Search for New Physics

- For a nice overview see: S. Stone “BTeV Physics” athttp://doe-hep.hep.net/P5StoneMarch2003.pdf

## First  Example: Supersymmetry 

- Supersymmetry: In general 80 constants & 43 phases
- MSSM: 2 phases (Nir, hep-ph/9911321)
- New Physics in Bo mixing: D , Bo decay: A, Do mixing: K

| Process | Quantity |        SM | New Physics |
| --- | --- | --- | --- |
| BoJ/Ks | CP asym |     sin(2) | sin2(D) |
| BoKs | CP asym |     sin(2) | sin2(DA) |
| DoK-+ | CP asym |          0 | ~sin(K) |

- New Physics

- Difference
-  NP

## Rare b Decays

**Rare b Decays**

-  Search for New Physics in Loop diagrams
- New fermion like objects in addition to t, c or u
- New Gauge-like objects in addition to W, Z or g
-  Inclusive Rare Decays including
-  bs
-  bd
-  bs+
-  Exclusive Rare Decays such as
- B
- BK*+ Dalitz plot & polarization

**********+********-**

- BoK*

## Yield, S/B for Rare b Decays

| Reaction |  B (10-6) |  Signal |   S/B | Physics |
| --- | --- | --- | --- | --- |
| BoK*o+- |      1.5 |   2530 |    11 | Polarization; Rate |
| B-K-+-
 |      0.4 |   1470 |     3.2 |  Rate |
| bs+-
 |      5.7 |   4140 |     0.13 |  Rate; 
Wilson coefficents |

**Notes:**
Discovery potential here

## BTeV data compared to Burdman et al calculation 

Dilepton invariant mass distributions,forward-backward asymmetrydiscriminate among the SM and various supersymmetric theories.(Ali, Lunghi, Greub & Hiller, hep-ph/0112300)

One year for K*+-, enough to determine if New Physics is present

- Dilepton invariant mass distributions,forward-backward asymmetrydiscriminate among the SM and various supersymmetric theories.(Ali, Lunghi, Greub & Hiller, hep-ph/0112300)
- One year for K*+-, enough to determine if New Physics is present

**Polarization in B****o********K*****o********+********-**

## Second Example: Extra Dimensions

**Second Example: Extra Dimensions**

- Aranda & Lorenzo Diaz-Cruz, “Flavor Symmetries in Extra Dimensions”    (hep-ph/0207059) (Buras et al. hep-ph/0212143)
- Extra spatial dimension is compactified at scale 1/R = 250 GeV on up
- No effect on |Vub/Vcb|,   Md/Ms , sin(2)

- –8%

- –100

- +72%

- |Vtd|

- 

- Bs -> 

## Summary

- Heavy quark physics at hadron colliders provides a unique opportunity to
- measure fundamental parameters of the Standard Model with no or only small model dependence
- discover new physics in CP violating amplitudes or rare decays.
- interpret new phenomena found elsewhere (e.g. LHC)
- Some scenarios are clear others will be a surpriseThis program requires a general purpose detector like BTeV with
- an efficient, unbiased trigger and a high performance DAQ
- a superb charged particle tracking system
- good particle identification
- excellent photon detection

## Changes wrt Proposal in Event Yields & Sensitivities

- We lost one arm, factor = 0.5
- We gained on dileptons
- From RICH ID
- in proposal we used only +-, now we include e+e-
- factor = 2.4 (or 3.9), depending on whether analysis used single (dilepton) id
- We gained on DAQ bandwidth, factor = 1.15
- Gained on D2 for Bs only, factor = 1.3

| Mode | Yield
proposal |   Yield
  factor |   Yield
one-arm | Quantity
Err(prop) (D2) | Quantity
Err(1arm) (D2) |
| --- | --- | --- | --- | --- | --- |
| BoJ/ Ks | 80,500 | 0.5*3.9*
1.15=2.24 | 168,000 | sin(2) 
0.025  (0.10) | sin(2)
0.017 (0.10) |
| BsJ/() |   9,940 | 0.5*2.4*
1.15=1.38 |   12,600 | sin(2)
0.033 (0.10) | sin(2)
0.024 (0.13) |
| Bs Ds K- | 13,100 |  0.5*1.15
   =0.58 |    7,500 |  
6o  (0.10) | 
  8o  (0.13) |