# Presentation: 571822

## B hadron masses and branching ratios at CDF

- Saverio D’Auria, University of Glasgow
- For the CDF collaboration

## Contents

** ****Trigger types at CDF**
** ****Masses at CDF**
** ****Results on mass measurements:**
** ****B********,B****0**** **
** ****B****s**
** ********b**
** ****Branching fractions at CDF**
** ****Results on branching fractions:**
** ****B****s**** ******** D****s**** ******
** ********b**** ******** ******** ******
** ****B ******** h****+****h****-**** **
** ****Conclusions and prospective analyses**

**Related talks:**
- S. Farrington:
-      B lifetime and Flavour tagging at CDF (HF)
- S. Giagu:
-      Results on CP violation from CDF (CP)
- J. Thom:
-      Rare Charm decays from CDF (RareDecays)
- T. Shears:
-     Bottom and Charm quark
-     production in CDF (QCD)
- C. Ginsburg:
-     CDF run-II muon detector system (DDH)
- G. Bolla:
-     Commissioning, operations and first results
-     of the CDF run-II-a Silicon (DDH)

## Introduction

- Used in this analysis:
- COT tracking chamber, XFTrigger
- (1/*p**T*) ~ 0.1% GeV –1; (hit)~150m
- dE/dx K- separation is 1.3  at *p*t > 2GeV/c
- Silicon detector, SVTrigger:
- 5 Layers, i.p. resolution 30 m, SVT

- Integrated Luminosity

## Trigger types

- B-Physics at CDF is based on 3 trigger types:
-  **di-lepton trigger (“J/********”)                                                 **
** ****two tracks with d****0**** > 120********m (“2-Track Trigger”)**
-  lepton + track with impact parameter > 120m (“lepton+SVT”)

- }Used here

- SVT:  33m beam  35m res.

## Masses at CDF

- The di-lepton trigger has a large statistics of fully reconstructed B decays
- Mass scale calibrated on J/, check performed on ’ and *Y*(1S)

- dE/dx: use GEANT description
- Material adjustment
- Magnetic field: +0.165%

|  | CDF mass | PDG mass |
| --- | --- | --- |
| ’ | 3685.80  0.12 | 3685.96  0.09 |
| Y(1S) | 9461.1  1.5 | 9460.30  0.26 |

## Mass measurements: results

- Analysis cuts:
- J/ mass window:  ±80 MeV
-  mass window:  ±80 MeV
- Decay length (B):  >100 m
- Pt (B)                     > 6.5 GeV

- Analysis cuts:
- J/ mass window: ±80 MeV
- Pt±)                  :  > 2  GeV
- Decay length (B):  >100 m
- Pt (B)                     > 6.5 GeV

## Mass measurements: results

- Analysis cuts:
- J/ mass window:  ±80 MeV
-  mass window:     ±15 MeV
- Decay length (b):  >100 m
- Pointing cut: cos B>  0.95

- Analysis cuts:
- J/ mass window:  ±80 MeV
-  mass window:     ±10 MeV
- Decay length (Bs):  >100 m
- Pt (Bs)                     > 6.5 GeV

## Mass measurements: summary

*Prospects:*
- what can we do with more statistics
-  Systematic error will decrease: correct for smaller effects
-  Statistical error will scale with integrated Luminosity: mass differences
-  Mass of other Meson, Baryons will be measured.

|  |      Mass (MeV/c) | Best single meas. PDG   | PDG value |
| --- | --- | --- | --- |
| B+ | 5279.32  0.68  0.94 | 5279.1  0.4  0.4 | 5279.0  0.5 |
| B0 | 5280.30  0.92  0.96 | 5279.1  0.7  0.3 | 5279.4  0.5 |
| Bs | 5365.50  1.29  0.94 | 5369.9  2.3  1.3 | 5369.6  2.4 |
| b | 5620.4  1.6  1.2 | 5621 4  3 | 5624  9 |

| Mass constrained fit | 0.8 |
| --- | --- |
| B-field corrections | 0.2 |
| dE/dx corrections | 0.2 |
| Alignment/tracking | 0.4 |

- Main sources of systematic errors

- MeV

## Branching fractions at CDF

**Ratios of Branching Fractions**
-  Uncertainties on b cross section (+ 9% c.m. Energy)
-  Systematic effects on trigger efficiency
-  Rely on other measurements for
-  Production fractions *f**x* allow for measurement in future
-  Branching ratio of control mode
-  Branching fractions to daughter’s daughters
**Fully reconstructed decays from the “Two-Track Trigger” stream**

- e.g.

## Branching Fractions

-  Same mode for:
-  D* peak also visible.

- Normalization decay mode: Bd  D   

- 

## Branching Fractions

## Branching Fraction: s  Ds 

- Branching Fraction: s  Ds 

- Results:

- From MC:
- R = 1.08  0.02

- From PDG
- Rbr = 2.53  0.65

- From data fit:
- Ns =   44  11 (stat)  7 (sys)
- NB0 = 505  44 (stat)  20 (sys)

***New measurement !***
- Previous limit set by OPAL: BR (Bs  Ds  ) < 13%

***BR*****(B****s**** ******** D****s**** ************) = ( 4.8******** 1.2******** 1.8******** 0.8******** 0.6) ********10****-3**** **

*(Stat)   (BR)   (sys)   (f**s**/f**d**)*

## Branching Fractions

- “Reflections”: take a  for a *p *and
- the control channel B0(K  
- has a reflection peak right under the
- signal.
-  Use MC to parametrise the shape.
-  Use data to normalize the amplitude
-  Take into account into fitting function

## Branching Fraction: b  c 

- Branching Fraction: b  c 

- Results:

- From MC:
- R = 1.20  0.02

- From PDG
- Rbr = 1.82  0.49

- From data fit:
- Nb =   96  13 (stat) +6 –7 (sys)
- NB0 = 321  22 (stat)  20 (sys)

***New Result !***

- Previous observations:
- Delphi 3 evts
- Aleph  4 evts

- BR(b  c ) = (6.5 1.1(stat)  0.9(sys)  2.3(BR,f) ) 10-3

## Branching Fractions: B h+ h(’) - 

-            required to be trigger tracks.
-   Optimise offline Cuts on MC signal, data sideband:

- Branching Fractions: *B**** h**+ **h**(’)** **-*

-  Isolation:
- Efficiency from data

- Defined in a cone about the B axis:

## Branching Fractions B h+ h(’) - 

-  Total width due to several different contributions.
-                                 on top of each other
-   Disentangle using:
-  Invariant Mass
-  Relative momentum
-   PID

- ← Most Important

- {

- Kinematic Separation

- Monte Carlo:

- Different signal contributions:

## Branching Fractions B h+h(’) - 

- Branching Fractions *B**** h**+**h**(’)** **-*

- Choose 2 variables:

- Signal Likelihood:

- Monte Carlo:

- Kinematic separation:

-  G1,****(ID1) G2,****(ID2)

## Branching Fractions B h+h(’) - 

- Branching Fractions *B**** h**+**h**(’)** **-*

|  |   |
| --- | --- |
|  |  |
|  |  |
|  |  |

- Yields:

- Ratio of B-factories average:

- Present Results:

- Consistent
- with no CPV

- Using B-factories average for
*BR*(Bd) = (18.5  0.1) 10-6
- We obtain:
*BR*(Bd) = (4.81  2.05  1.02) 10-6

- [Heavy Flavor Averaging Group]

## Branching Fractions: forthcoming channels 

- e.g.

## Conclusions:

-  Mass and Branching ratio techniques in CDF are well established:
-  new channels are now available thanks to improved trigger (SVT)
-  Most precise measurement of b and Bs mass
-  New branching ratios have been measured:
-  Bs Ds  and
- bc 
-  BR sensitivity: O(5 10-6) with present data.
-  We have just opened the lid: a large number of new measurements
-    will be performed in the near future.