# Presentation: 802785

## e+e- Annihilation into Quasi-two-body Final States  at 10.58 GeV --Expected or unexpected? 

*Introduction*
*Analyses of exclusive processes:*
*    **--e**+**e**-**********,****** **(C=+1) TVPA*
*    **--e**+**e**-****+****- **(C=****1** **? )   1 *****+TVPA FSI?*
*    **--e**+**e**-**** (C=****1** **)       s dependence *
*    **--e**+**e**-****p****p p****p          fragmentation*
*                                     **(very preliminary)*
*Summary *
*Outlook*

**Kai Yi, SLAC**

- Kai Yi, BaBar/SLAC

## Introduction—General Information

**Introduction—General Information**

*********(e+e-************hadrons) ***
***~ 3 nb @10.6 GeV***

***  ******The design goal of the B factory is the study of B physics.  ***
***  ******At ************s~10.6 GeV, ************(e******+******e******-************hadrons) ~3 nb and <N******ch******> ~8***
*** ***
***  ******Large integrated luminosity (~500 fb******-1******) ************ can study low-multiplicity exclusive hadronic   processes with  ************ values ~fb;  this provides tests of pQCD at the amplitude level.***
***                                      ***

- PDG 2006

**Hadronic cross section**

- Kai Yi, BaBar/SLAC

## The BaBar Experiment

**The BaBar Experiment**

- *e****e******collisions at 10.6 GeV, designed for CP violation in B decays*
***Different beam energies:*
***E**e******= 9.0 GeV*
***E**e******= 3.1 GeV*
*c.m.-lab boost, ****=0.55*
***Asymmetric detector*
***track coverage [/4****]~0.92*
***EMC coverage [/4****]~0.90*
***with excellent performance                    ****High luminosity:*
***Good tracking, **mass **resolution               ****~ 480 fb**-1** **accumulated*
***Good ****, ********reconstruction.                          ****1.6 billion **e****e******q****q evts*
*Good **e,****,****,K,p **ID                                       ****0.5 billion **e****e******B****B evts*
***Data sample for today:  ************L******~******343 ******fb******-1****** @10.58 GeV (OnPeak);  ************L******~******36****** fb******-1******  @10.54 GeV (OffPeak) ***
**

**Barrel now **
**has LSTs**

- Kai Yi, BaBar/SLAC

## Data input and physics output

**Data input and physics output**

| Peak luminosity
(cm-2s-1) | 1.201 x 1034 |
| --- | --- |
| Best shift | 329.7 pb-1 |
| Best day | 891.2 pb-1 |
| Best week | 5.25 fb-1 |
| Best month | 18.83 fb-1 |
| BABAR logged | 477 fb-1 |

- Run 6

|  | BABAR |
| --- | --- |
| Luminosity | 477fb-1 |
| Journal Papers | 312 |

- Kai Yi, BaBar/SLAC

## Introduction—Processes at B Factories

*One photon**  processes*

*Two photon** processes*

*Two-Virtual-Photon-Annihilation, *
*TVPA; **new observation*

*A subset of e**+**e**-****q****q processes;*
*or via ISR, a  test ground for QCD*

- ~nb

- ~fb

***Exclusive hadronic final states***

***TP***

***Today’s topic***

- Kai Yi, BaBar/SLAC

##  Observation of e+e-/ (C=+1)

- Kai Yi, BaBar/SLAC

##  Observation of e+e-/ (C=+1)

-  Observation of e+e-/ (C=+1)

*PRL 97, 112002 (2006)*

- @10.6GeV

*Select events with invariant mass of (K**+**K**-****+****-**/****+****-****+****-**) within **170** MeV of c.m. energy.*

*We are interested in **.*
*assume m(****0**)<2.2 GeV/c**2**, *
*p*(****0**)>4.8 GeV/c*
*Only **one entry** in the region of interest**** (no ambiguity)***

- p*12

- p*14

**4.8 GeV**

***No entry***

*Data*

- Kai Yi, BaBar/SLAC

##  e+e-/--generate level simulation

- at 10.6 GeV, large kinematic separation between modes
- ...and between “correct” and “incorrect” pairings

- 

-  e+e-/--generate level simulation

- Kai Yi, BaBar/SLAC

## e+e-/--scatter plots in data

- e+e-/--scatter plots in data

***signal tiles******:***
***0.5<m************<1.1 GeV/c******2****** (************)  ***
***1.008<m******KK******<1.035 GeV/c******2******(************)***

*Use **binned log-likelihood** fit *
*over 9 tiles to extract signal*
*Including components:*
***KK***
*   **+ ***
*   **+ ****f**2**(1270)*
*   **+***

***Threshold***

- lego

- Kai Yi, BaBar/SLAC

##  e+e-/--mass projections

- f2

- +- against “”

- +- against “”

- K+K- against “”

*Correlated **** and ****0** signals*
*Relativistic Breit-Wigner *
*lineshapes used in the fit*

-  e+e-/--mass projections

- f2

- 

- 

- total

- background

-  background

-  background+f2

- total

- Kai Yi, BaBar/SLAC

##  e+e-/--On-, Off-resonance comparison

|  |         All Events
 |   Yield @
10.58 GeV |   Yield @
10.54 GeV | Expected continuum @
10.56 GeV
(from L ratio) |
| --- | --- | --- | --- | --- |
|  00  | 124343          >> 5 | 1138 42 | 104 14 | 112 4 |
|  0 | 14713            >> 5 | 135 13 | 14  4 | 13 1 |

*consistent*

*The extracted signals: *

* **C parity conservation**** Y(4S) production do not contribute *
*  **Consistent with **continuum production****combine On- and Off-resonance data.*
* **Signals large enough to analyze the angular distributions and investigate *
*  **the production mechanism for these final states.*
* **First observation of (C=+1) hadronic final states in e**+**e**-** collision. Likely by TVPA.*

*significance*

*Yield*

-  e+e-/--On-, Off-resonance comparison

- Kai Yi, BaBar/SLAC

## e+e-/--TVPA expectation for cos*

- Kai Yi, BaBar/SLAC

##  e+e-/--Angular distributions in data

*Production angle *********polar angle of **** *
*or ****forward** in CM consistent with *
*expectation for TVPA*

* ****0****0*

***H** for ****+*

*1+cos**2***** for comparison*

-  e+e-/--Angular distributions in data

*Efficiency-corrected projections*

*sin**2****H** distributions as expected*
*For **TVPA** with quasi-real photon*

- ********

- ****

*Helicity angle ****H**—the angle between *
*daughter and recoil in the mother *
*rest frame *

* ****0*

* ****0*

***H** for ****+*

***H** for K**+*

- Kai Yi, BaBar/SLAC

##  e+e-/--Cross sections

* **The observed angular distributions **support TVPA production:*

* **The measured cross sections (1.008<m****<1.035 GeV, 0.5<m****<1.1 GeV, |cos*****|<0.8) :*
* ****(****0****0**)=20.7****0.7(stat) ****2.7(syst)** **fb       **reminder:**    *
* ****(****0**) =  5.7****0.5(stat) ****0.8(syst)** **fb**       ****(e**+**e**-****hadrons @10 GeV) ~ 3 nb*
* **Theory calculations (after the measurement) consistent with our results:*
*                   **hep-ph/0606155                        hep-ph/0608200*
* ****(****0****0**)=        **21.4****0.7                                17.7****0.6                       fb *
* ****(****0**) =          **6.0****0.1                                   5.6****0.2                      * *fb *

-  e+e-/--Cross sections

- Kai Yi, BaBar/SLAC

##  e+e-/--VMD model calculation

-  e+e-/--VMD model calculation

* **Assuming the **e**+**e**−** **→** ********** process followed by conversion of  *****  into V**1** and V**2**, with *
*  **effective coupling e/f**1** and e/f**2 **.  The cross section in c.m. frame  can be written as:*

* **Obtain effective coupling  through meson’s leptonic width:*

* **Calculation with this simple VMD model agree with our measurements.*
*   **More calculations based on VMD are summarized in next slide:*

*M. Davier et al, hep-ph/0606155*

- Kai Yi, BaBar/SLAC

##  e+e-/--VMD model calculation

* **Belle first observed J/**** ****c**(c****c) at a level 10 times higher than QCD prediction*
*  **through missing mass recoiling against the J/****. *
* **J/****J/**** was once proposed to explain the high rate. Its cross section was estimated *
*  **to be ~ 7 fb, now ~2.5 fb **(hep-ph/0608200).*
* **Not yet observed.*

*J/****J/***

- Kai Yi, BaBar/SLAC

##  e+e-/—VMD model calculation

* **TVPA contribution to **muon (g-2) is small with the current *
*   **precision by extending our results to low energy *
* **Removes a possible uncertainty source in g-2 calculation *
* ****2**/**** (pi-rhonium, mixing of **** and pionium)?  *
*   **0705.0757[hep-ph]*

-  e+e-/—VMD model calculation

* **Discrepancy between **** decay data and e**+**e**-** data as input.*
* **Interpretation of e**+**e**-** cross section ignores C=+1 process.*
* **How much TVPA contribute? One of our motivations*

*Eur. Phys. J. 31, 503-510 (2003)*

*Spectral function*

*R value from e**+**e**-****VV(C=+1), |cos*****|<0.8,  **(hep-ph/0606155)*

- Kai Yi, BaBar/SLAC

## Observation of ee → 

- Kai Yi, BaBar/SLAC

## Observation of ee → 

* **Single photon (J**PC** = 1**--**)*

* **Other possibility: **TVPA (C = +1) followed by FSI **→** unlikely?*

*In general:*
*C(****+****-)**=(-1)**L+S**, **+** or **-**; *
*P(****+****- )**= **(-1)**L**; *
*Single photon production***
*L **odd, **S **even, **I(****+****- )=**1**(Bose Statistics).*

*No angular correlation predictions for this mechanism*

*379 fb**-1**, BaBar Preliminary*

- Kai Yi, BaBar/SLAC

## ee→—QCD prediction and event selection

*One QCD model predicts (PRD 24, 2484) s dependence and production angle:*
*********F******00************1/s******2******, sin*************2******;      ************F******10******<1/s******3******, 1+cos*************2******;       ************F******11******<1/s******3******, sin*************2******;***
*@10 GeV, F**00** is expected to dominate.*
*Test QCD at the amplitude level in helicity structure.*
*Select:*
*two tracks: ********and ********two good *******
***momentum balance, m********** < 1.6 GeV/c2*
***|m****************** - E**CM** |<280 MeV*

**e********e********→********************—QCD prediction and event selection**

- Kai Yi, BaBar/SLAC

## ee→—Scatter plot and mass projections

*Clear signal for **e****e**** **→ *********
*2D Likelihood Fit in (m****-****0**, m****+****0 **) plane:*
* **Signal function= product of P-wave relativistic BWs*
* **** **= threshold function*
* **Linear combinatorial background*

*Mass projections*

**e********e********→********************—Scatter plot and mass projections**

- Kai Yi, BaBar/SLAC

## ee→—Cross section

*   **(|cos*****|<0.8, |cos******|<0.85, 0.5<m******<1.1)                       *
* **Extend to full angular range assuming 1 ***** production:*
*  ****(**e**+**e**-** **→ ****+****-**) = (**20.0 ± 1.6** ± 3.6 ± 1.7**) fb preliminary (**no prediction**)*
*  ****(**e**+**e**-** **→ ****0****0**) ~ **130** fb**      **hep-ph/0606155*
*  ****(**e**+**e**-** **→ ****0****0**)>> ****(**e**+**e**-** **→ ****+****-**)**; **FSI** possible explanation?*
* **No evidence for  Y(4S) → ****+****-** .*
* **e**+**e**-**→****+****-** seen in **ISR** data; **e**+**e**-**→****0****0 **is not seen in ISR as expected.*
*  **Will study cross section s dependence using ISR data and this result. *

**e********e********→********************—Cross section**

- Kai Yi, BaBar/SLAC

## 

****

****

* *****--production angle, ***** is not well defined (beam depolarization)*
*  ****+**--****+** helicity angle,   ****+**-- ****+** azimuthal angle*
*  **Similar for ****-** *

* **Our coordinate system:*

**e********e********→********************—Coordinate system**

- Kai Yi, BaBar/SLAC

## ee→—Angular correlation calculation

*   **Can be expressed as:*

**e********e********→********************—Angular correlation calculation**

- Kai Yi, BaBar/SLAC

## 

*(1,-1), (-1,1) (angular momentum).  The remaining possible amplitudes are:*
*                             **F**11**, F**10**, F**-1-1**, F**-10**, F**01**, F**0-1**, F**00*

****

*CP conservation *****

**e********e********→********************—Angular correlation calculation**

*i.e. only 3 independent amplitude*

- Kai Yi, BaBar/SLAC

## ee→—Angular correlation calculation

***investigate individual angular projection by integrating over the other angles:***

*** ******By integrating, we lose strong phase information. ***
*** ******The most separation power is from dN/dcos******************.  The F******00****** amplitude contribution ***
***goes to zero for ******************=90******o****** .***
*** ******The amplitudes are correlated; intensive Toy MC has been done to validate ***
***  ******the procedure. No bias is found from Toy MC studies.***

**e********e********→********************—Angular correlation calculation**

- Kai Yi, BaBar/SLAC

## ee→— correction and background subtraction 

***  ******--non-flat dependence of ************ on cos************* and cos****************** ***
***  ******--use  a 3D(cos*************,cos************+******,cos************-******) table to correct each event ***
***  ******--the method is validated on an independent MC sample.***
*** ******Background subtraction using sPlot***
***  ******--weight each event by sWeght obtained from 2D mass fit ***
***  ******--consistent with conventional way.***
*** ******Weight each event by sWeight and ************ to produce ***
***  ******signal angular distributions.***

**e********e********→********************—******** correction and background subtraction **

- Kai Yi, BaBar/SLAC

## ee→—Fit to the projected angular distributions 

- BaBar Preliminary

*Helicity angle*

*Production angle*

*Azimuthal angle*

*Simultaneous fit to the*
*five distributions.*
*F**00** dominates but *
*Cannot explain all *
*pQCD predicted |F**00**|~=1, and*

*Non-zero amplitude***
*          **|F**00**| =1*

- Kai Yi, BaBar/SLAC

## ee→—Amplitude result 

* **Fit normalization constraint:*

- |F00|2 ≠ 1, (e+e- → ) > (e+e- → ); no evidence for Y(4S) → 

-  Are we seeing TVPA + FSI?
* **--Combine with ongoing ISR analysis to measure s dependence of the *
* **cross section for each individual amplitudes to investigate FSI.*
* **Any connection between B****VV polarization puzzle and e+e-****VV?*

**e********e********→********************—Amplitude result **

*x4*

*x2*

*--Prediction:*

*--BaBar Data:*

- Kai Yi, BaBar/SLAC

## Observation of e+e- at ~10.6 GeV

- Kai Yi, BaBar/SLAC

## e+e-  is analogous to e+e-J/c ( has s-sbar content) 
     Interesting because observed (e+e-J/c ) 10x higher than QCD predictions 

Provides information on s-dependence by combining with a CLEO measurement at lower energy

Select:
       -- exactly two tracks, identified as K+ and K-
       --two good g candidates with deposited energy greater than 500 MeV
       --momentum |pK+K-|<0.2 GeV/c in the c.m. frame
       -- a pairing with both mK+K- <1.1 GeV and 0.4<m < 0.8 GeV/c2 
       --select events within 230 MeV of the nominal ECM

*     **Interesting because observed ****(e**+**e**-****J/****c** ) 10x higher than QCD predictions *
*      *
*Provides information on s-dependence by combining with a CLEO measurement at lower energy*
*Select:*
*       **--** exactly two tracks, identified as K**+** and K**-*
*       **--two good g candidates with deposited energy greater than 500 MeV*
*       **--momentum |p**K**+**K**-****|<0.2 GeV/c in the c.m. frame*
*       **-- a pairing with both m**K**+**K**- <1.1 **GeV and 0.4<m**** < 0.8 GeV/c2 *
*       **--select events within 230 MeV of the nominal E**CM*

- Observation of e+e- at ~10.6 GeV

*PRD (RC) 74, 111103(2006) *

- Kai Yi, BaBar/SLAC

## e+e---Signal and scatter plot

*PRD (RC) 74, 111103(2006)** *

- @ 10.58 GeV

- @10.58+10.54 GeV

- 

- 

*We  see **** correlation. *
*Use a two-dimensional log-likelihood fit to extract signal:*
*P-wave relativistic Breit-Wigner for ****; Gaussian resolution function for **** *

- Kai Yi, BaBar/SLAC

## e+e---Mass projections

*Yield for **1.008<m****<1.035 GeV/c**2**, and **0.4<m****<0.8 GeV/c**2** :*
*All data: **24****5 **events          @10.58 GeV: 20****5       @10.54 GeV: 3****2*
*Significance: **6.5 **** *
*U.L. for BF of Y(4S) decay @90% CL based on **-10 **** 21** events: **2.5X10**-6*

*Mass projections*

- e+e---Mass projections

- Kai Yi, BaBar/SLAC

## e+e---Coordinate system

- e+e---Coordinate system

* ****(1**--**), ****(0**-+**), ****(1**--**), P conservation**** L=1, assuming one ***** production.*
* **In helicity base, we have only one amplitude: F**10**.*
*   **(F**00** is forbidden due to vanishing CG coefficient) *
*We have a similar coordinate system:*

*We ignore the **** decay angular distributions, they are flat.*

- Kai Yi, BaBar/SLAC

## e+e---Angular correlation calculation

- e+e---Angular correlation calculation

*Similarly, we can calculate the total helicity amplitude as:*

- Kai Yi, BaBar/SLAC

## e+e---Angular distributions

* **Weight** isotropic MC angular distributions as above to obtain  efficiency estimates.*
* **The efficiency dependence for each angular distribution is approximately flat, which *
*  **simplify the correction procedure. *
* *
* **Distributions in data are consistent with predictions within the limited statistics*

- e+e---Angular distributions

* **Due to low statistics, we investigate the angular projections by integrating *
*   **over the other angles:*

- Kai Yi, BaBar/SLAC

##  e+e---Cross section

*For 1.008<m****<1.035 GeV/c**2 **and** **|cos*****|<0.8** **, the cross section after radiative corrections  is measured as:*
*                  ****(****)=2.1****0.4(stat) ****0.1(syst)** **fb*
*Extending to** **(|cos*****|<=1) by assuming a 1+ cos**2***** distribution, this becomes:*
*                  ****(****)=2.9****0.5(stat) ****0.1(syst)** **fb*

*Combine with CLEO measurement at lower energy; 1/s**3** energy dependence favored over 1/s**4 **(pQCD prediction), assuming continuum production. *
*Analysis of BaBar ISR data is ongoing; see preliminary result next slide.*

-  e+e---Cross section

*Recent theory prediction (after the measurement) (hep-ph/0702065): *
***~3.1~4.3 fb, and 1/s**3** dependence favored.*

- Kai Yi, BaBar/SLAC

## e+e---Preliminary result from ISR

- e+e---Preliminary result from ISR

* **BaBar preliminary ISR (****ISR**KK****) result*
*   **possible structure(s) near 2.2 GeV*

* **At “high”-E**CM**, data (including 10.6 GeV point) are consistent with 1/s**4** *
*  **CLEO measurement seems to be low.*
* **Dispersion relation phenomenology EPJ A31, 665 (07)*
*   **--explains the data nicely in terms of ****’ and ****’ resonances*
*   **--confirms 1/s**4** asymptotic behavior, it is actually helicity F**10** amplitude*
*     **implies that pQCD is right, favor FSI for e****e**** **→ ***********

- BaBar Preliminary

- Kai Yi, BaBar/SLAC

##    Connection to LHC

-    **Connection to LHC**

* **Angular correlations to determine J**PC** of X(H) particle*
*  **--Simple way:  assume one configuration, compare to data*
*  **--General way: assume all configuration, decide the best one.*
*    **e.g.,  X(H)****ZZ*
* **sPlot to subtract background. i.e., H****ZZ (may not needed)*
* **Test PYTHIA prediction. Help refine the fragmentation model of PYTHIA*
*   **for a more precise modeling of the jet content.*
*   **Even the energy at BaBar is low compare with LHC, but we *
*   **have information from data.*

- Kai Yi, BaBar/SLAC

##    Summary

*At BaBar we have: *
*  **Made the first observations of the **TVPA** hadronic processes:*
*                     **e**+**e**-********** **and** e**+**e**-*****
*    **and the angular distributions support TVPA mechanism.*
* **Observed the process **e**+**e**-** ****+****-**; the measured helicity amplitudes contradict a pQCD expectation at 3.5 ****, assuming single ***** production.*
*   **--Further investigation using **ISR **data on **e**+**e**-** ****+****-** **will provide  information on the s dependence and perhaps on understanding of the role of **FSI** (if any).*
* **Observed the process **e**+**e**-** **** **and measured the cross section; this   provides an interesting test of the QCD prediction for the energy dependence, assuming continuum production.*
* **Observed **e**+**e**-** **** p****p p****p**, presently being investigated.*
* *

- Kai Yi, BaBar/SLAC

##    Outlook

* **We also see evidence of many other exclusive final states. Results from these      *
*  **channels will provide further detailed tests of QCD and hadronization models.*
*       *
*                                       **However**              *
*              *
* **B factories provide opportunity to search for new particles. *
*   **X(3872), Y(4260), Y(4350), Z(4430)**+**, Y(4660)**...  (unexplained)*
* **Z(4430)**+**, if confirmed, has strong implication for other states. *
* **May classify them as multiple-quark states, hybrid, glueball,...*
* **Glueballs and hybrids gain mass through the strong interaction (solely for *
*   **glueball). A unique place to study: **mass creation by strong interaction.*
*  **(i.e., proton gains only a few percent of its mass through Higgs mechanism)** *
*  *
*                                      **lots of activities are going on...*

- Kai Yi, BaBar/SLAC

##    Outlook

*   **More fundamental question:  How bosons, fermions gain mass? *
*                             **The Higgs mechanism?*
* **Updated W and top quark masses improved constraint on *
*  **Higgs mass:   ***M****H**** = 76 ± 31 GeV ****(****m****H****/m****H**** ****39%)      (winter 07)**
*  **LEP limit:  **>114.4** GeV @95% CL*
*  *
* **New possibilities proposed: *
*  **--**H****2a****X, **a is non-SM particle. (hep-ph/0608310)*
*  **--CP-Odd NMMSM**  A**0****.(hep-ph/0404200, hep-ph/0612031) *
*  **(put BaBar in the game)*

- Kai Yi, BaBar/SLAC

##    Outlook

*           ****New idea at LHC: ******F******lavor ******C******hanging ******H******iggs ******D******ecays (******FCHD******s)***
***           ******BR is estimated to be about 10******-4******-10******-3***
*  ****MSSM ************(h******0******,H******0******,A******0******)************b************s******, Phys. Lett. B 647, 36-42 (2007)***
***  ******QCD background free, challenge on s jet identification (impossible?)***
***    ******Trigger possible?***
***  ******Some ideas on s jet ID (no guarantee to work):***
***     ******--p******T****** of K******s******/************/************/...? Anything else?******hep-ex/9702009, hep-ex/9908038,...***
*     ****--impact parameter separates ******b (c) from s***
***     ******--Jet charge tagging separates up-type from down-type***
***     ******--use MVA technique to combine?   ***
***     ******--Topological Vertex help??***
***                                               ******Thank you!***

- Kai Yi, BaBar/SLAC

##    Backup—BaBar detector perfomance

- Kai Yi, BaBar/SLAC