# Presentation: 466755

## HOT TOPICS IN CHARM PHYSICS

**Stefano Bianco**
**Laboratori Nazionali di Frascati dell’INFN**

**HOT TOPICS IN CHARM PHYSICS**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## CONTENTS

- Charm quark and SM
- D0D0 mixing
- CP violation
- Lifetimes
- Charm & Light Quarks:
-  in Semileptonic Decays
-  in Dalitz plot analyses
- Spectroscopy
- Outlook and Conclusions
- Ref: SB, Fabbri, Benson, Bigi Riv.Nuovo Cim. 26,7-8, 2003 hep-ex/0309021

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## High-impact Physics & Engineering Database

- CPV, mixing and
- rare decays in
- Charm sector are a
*probe*  for *New Physics*

**Why (only)**
** ****3 families ?**

- Quark c is the only HQ
- up-type probe

- In the charm sector,  SM
- contributions to CPV, mixing
-  and rare decays are small (GIM)

- But how small?
- CPV asimm 10-3
- D0D0bar mixing 10-3—10-10
- Rare decays 10-9 – 10-19

**Higgs ?**

-  HI ENERGY

**SM**

**FSI corrections **
**are important**

- Quantitative predictions via
- 1/mQ expansions are possible

- Quark **c** is the lightest
-  heavy quark

-  **Studying the c-quark provides:**
**  ****Engineering Database  for b-physics**
**  ****Sensitivity and discovery potential for New Physics**

**FSI corrections **
**are important**

******QCD**

-  LO ENERGY

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Here is my very personal view of charm quark physics within the SM frame. I see three main branches of unsolved problems: the Higgs, ACD at low mom transfer, and families. The Higgs mechanism referes to high energy experiments. The functioning of QCD at very low momentum trsfers in very non perturbative regimes chiralQCD attains the domain of low momentum transers. The third question is why there are three and only three families. Within quark families the c-quark has a peculiar role because: a) it is the lightest heavy quark, mc>Lambdaqcd. This means theorist should be ble to apply 1/mq expansions to get quantiative estimate. The rovescio della medaglia is that mc just sits in a very bust region of light quark resonances, therefore FSI must be important. On the other hand, the charm quark is the only up-type HQ. This means that thanks to cancellation mechansms such as GIM, one expects very small contributions from the SM in processes as CPV, mixing and rre decays. How small is small ? CPV asymm 10-3, mixing 10-3 etc. If this holds, therefore c quark is a probe for new physics. Hence the double valence: studying the c-quark provides an engineering dtabase for b physics, and it is a sensitive tool for new physics

## Charm discoveryK.Niu, E. Mikumo, Y. Maeda Prog. Theor. Phys. 46 (1971) 1644D+ K+ 

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Charm quark detectors over the years

**Charm quark detectors**** over the years**

- R704E760E835

**NOW**

- BABAR,BELLE

- CDF,D0

- BNL
- SPEAR
- ADONE

- COMPASS

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## D0D0 MIXING

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Formalism of P0-P0  mixing        

- and mixing amplitude is

- Mass and  width differences are parametrized
- by

**Formalism of **P0**-****P**0 ** mixing****    ****    **

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Let me now remind the key features of particle-antiparticle mixing this is irrespective of flavour and it applies to pseudoscalar mesons

## K0, D0, B0    _  Where’s The Difference ?

|  |    q |  SD/LD | x=m/ |        y=) |
| --- | --- | --- | --- | --- |
|    |    c |  SD~LD |    0.48 |            100% |
|    |     s | SD<<LD |       ? | <1% |
|    |    t | SD>>LD   |   0.75 |                 ? |
|    |    t | SD>>LD |     >22 |                 ? |

*K**0**, D**0**, B**0   ** **_  ***Where’s The Difference ?**

*Also: OPE-based limits*
- I.Bigi, N.G.Uraltsev Nucl.Phys.B592(2001)92

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Theoretical “guidance”

- From compilation of H.N.Nelson   hep-ex/9908021

**Triangles** are  SM x  **Squares** are SM y
**Circles **are NSM x

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
These are results from a compendium of H.N. Nelson from CLEO giving about 50 papers which predict values for the x (mass mixing) and y (width mixing) parameters. They span roughly 7 orders of magnitude which implies a rough 15 order of magnitude range of predictions for pure semileptonic mixing. I gather from this that mixing amplitudes on the order of a few percent certainly are “not out of the question” theoretically.

## TECHNIQUES FOR STUDYING D0D0 MIXING   (I)

- _

-  Measure *y**CP**, *the* y * parameter for CP eigenstates

-  Measure  *r*

**These Results**

**HADRONIC**
** ****DECAYS**

**SEMILEPTONIC **
**DECAYS**

**Also E791, BELLE**

- (1 +2)/2

**E791, CLEO, ALEPH**

**E791**

**TECHNIQUES FOR STUDYING**** D****0****D****0**** MIXING   (I)**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Mixing parameters as we saw are x,y, and r. It is unpractical to measure x (microeV), one than can measure ycp (y assuming cp conservation) or r.

## TECHNIQUES FOR STUDYING D0D0 MIXING   (II)

- _

-  Measure *r*

**HADRONIC**
** ****DECAYS**

**D* tags D****0**
-  **flavour**

**mixing**

**Cabibbo-****F****avoured Decay**

**Double Cabibbo-****S****uppressed Decay**

- Strong phase  
- between  CFD and DCSD mixes  x and   y

-  via

**TECHNIQUES FOR STUDYING**** D****0****D****0**** MIXING   (II)**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
To measure r one can select hadronic decays or semileptonic decays.

## TECHNIQUES FOR STUDYING D0D0 MIXING   (III)

- _

-  Measure *r*

**D* tags D****0**
-  **flavour**

**mixing**

**Cabibbo-****F****avoured Decay**

**SEMILEPTONIC **
**DECAYS**

-  via

**TECHNIQUES FOR STUDYING**** D****0****D****0**** MIXING   (III)**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Controlla se sono giusti I segni dei leptoni

## TECHNIQUES FOR STUDYING D0D0 MIXING   (Concl.)

-  Measuring **r****ws** in hadronic decays requires
-  to disuntangle **r****DCS** from **r**;
-  and the knowledge of ****
-  Measuring **r****ws** in semileptonic decays   provides the **r** parameter, but it is  experimentally more difficult

**TECHNIQUES FOR STUDYING**** D****0****D****0**** MIXING   (Concl.)**

- _

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## FOCUS ycp: Time evolutions

- FOCUS ycp: Time evolutions

-  Background subtracted and f(t’) corrected time evolution of **K****** and **KK** events in the final fit.

-  Before background subtraction

- (K) = 409.2 1.3  fs
- (KK) = 395.7 5.5 fs

**y****CP** = **3.42 ******** 1.39 ******** 0.74%**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
In focus, measurement of ycp is straightforward just make ratio of two slopes. A lot or systematics cancels out.

## Measuring the  DCS decay D*+ + (K+-)

-  Fitted *D*0 yields are plotted in the appropriate m bins.
-  Background is fit to:				   .
-  DCS signal is fit directly to the CF histogram signal region.

- Fit the m Distributions

- rWS= (0.404 **** 0.085 **** 0.025))%

- Measuring the  DCS decay D*+ + (K+-)

- CLEO:
- (0.332
****0.064
****0.040)%

**Phys.Rev.Lett. 86 (2001) 2955-2958**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
The D0 yields from these fits are then plotted in the appropriate mass difference bins and the D* signals are fit.  
	I’d like to note here that , because these are the D0 to Kpi fit yields, we have eliminated the contribution of D* tags from D0  backgrounds.  Here, the background is pure D0 to Kpi with random soft tagging pions and the enhancement in the signal region is due to real D* tags with real D0 to Kpi  decays .
	The mass difference background is fit to a this threshold function, and the DCS signal is fit directly to the Cabibbo favored histogram signal region.  By fitting in this way we eliminate large potential systematic errors due to our choice of signal parameterization.  Also the relative branching ratio comes directly out of the fit; it’s simply scale factor between the Cabibbo favored signal and the DCS signal.
	We find that rDCS is equal to (0.482+-0.093)%.  Without systematic erorrs, and of course this number is preliminary.

## STATUS OFD0D0MIXINGAS OF SPRING 2004

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## PHASE AMBIGUITY

**PHASE AMBIGUITY**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## CPV ASYMMETRIES

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Last topic of my talk is CPViolation and mixing searches. I already mentioned these effects are expected to be small in SM, and in principle are therefore probes, but one has to control very well long-distance effects caused by final-state interactions that are abundant for charm, and may fake the effect. Although Focus has published several results on CPV integrated rate asymmetries, I’ll just discuss very new preliminary results on asymmetries in Dalitz plots.

## CP VIOLATING INTEGRATED ASYMMETRIES

******i** = strong phase

**CP asymmetry:**

**2 different weak amplitudes**

**strong phase-shift**

**CP VIOLATING INTEGRATED ASYMMETRIES**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Search for CP violation via  Dalitz plot analysis of Singly-Cabibbo-suppressed Decays

-  Use full decay info, not only BR  must determine amplitude coefficients and phases

-  Final state results from the interference of all intermediate states

-  Differences between amplitude and/or phases patterns in a Dalitz analysis betw conjugate states (i.e., D+ vs D-), would be evidence of  CP violation
-      (ref. I.Bigi,A.Sanda “*CP Violation*”)

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Whys do we look for asymmetries in Dalitz plots ? Because there is much more info than in integrated rates. Differences between amplitude and/or phases patterns in a Dalitz analysis betw conjugate states (i.e., D+ vs D-), would be evidence of  CP violation .
Why do we need SCSD ? Because, contrary to CF and DCSD, they proceed via two (weak) amplitudes, whose relative phases are sensitive to CPV.
Must be SCSD because they contain contributions from two weak processes, tree-level and penguin. Neither CF nor DCSD contain two weak phases.

## CP violation:Dalitz analysis

**COEFFICIENTS** and **PHASES** for each amplitude

- Measured phase:

******=****************+**********

- CP conserving

- CP violating

- CP conjugate

**E831**

**a****CP****=0.006±0.011±0.005**

- Measure of direct CP violation:
- asymmetrys in decay rates of  **D************K********K **********

****

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Ds , D+ KK

- Ds+  K+ K+

- D+  K+ K+

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
The analysis starts from the selection of a very clean datasample. Two dalitz plot, we only use D+ in this study SCSD

##  D± KK

- Yield D**±** = 7106 92
- S/N D**±** = 8.62

- Preliminary

-  D**±** KK

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
This is a typical fit, dominated by Phi, K*892, K*1430, a0 lobes

## D+/D- split sample analysis

**Phases:**** ****D****±****,**** ****D****+****,**** ****D****-**** **

- D+/D- split sample analysis

**Preliminary!**

- No evidence  of CPV

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
And finally these are amplitudes and phases for total D+- sample (black),D+ (blue) and D-(red).  No evidence of CPV asymmetry, although reds are systematically higher than reds. But not statistically significant. Errors are only statistical.

## LIFETIMES

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Now the charm quark state is created and has a mass it is time to study how long it will take before it deays

## LIFETIMES

-  Measuring charm meson lifetimes is important to study    contribution of W-Annih e W-eXchange diagrams
-  Operator Product Expansion (OPE) Models
-   *review: G.Bellini, I.Bigi, P.J.Dornan, Phys. Rept. 289, 1(1997)*
-  Ratio [( D0)/( D**s**+)] <1  is sensitive to W-Annih
-  In OPE models, W-Annih operator is the same appearing in B semilep decays.

- (**c**0)  ( **c**0) ( **c**+) ( **c**+) ( D0) ( D**s**+) ( D+)

**SPECTATOR**

**SPIN-SPIN INTERCTN**

**PI, WA, WX**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Charm mesons and baryons show a wild variety of lifetimes, which is shown here schematically. If dynamics was only at the spectator level, lifetimes would be all proportional to GF2 and mc5, and CKM matrix element, ie all the same for
 same CF, SCS, DCF modes. Instead they are very different.
Measuring lifetimes is important to study in geral interplay between spectator diagram and WA WX. 
As instance we know that D0 lifetime is half than D+ lifetime. We attribute this to distructive interference of spectator graphs that D+ has and D0 does not. 
Review of exp and theory is in the bellini nigi dornan paper. Generally one takes a OPE approach and expand in inverse powers of mQ the width. Wlson coefficients are the operators each one is connected to one set of diagrams. As instance ratio D0/Ds prop to Wannih and in OPE Wannih also appears in B semilep decays

## Lifetime measurement technique

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
...
Fit is done maximizing likelihood with two terms, one is the expected number of events in t’ bin, the other is the background level  taken from the inv mass distribution. This standard method is effectively a combined lifetime-massplot fit.

## Charm Meson Lifetimes 

- Charm Meson Lifetimes

- 139433520 evts

- 68274360 evts

- 109877385 evts

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Charm Baryon Lifetimes

**Charm Baryon Lifetimes**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Quite naturally thanks to its great lifetime resolution, focus has always dominated the baryon lifetime measurements, as well. In this case scenario is more complicated since several diagrams can contribute to the hadronic partial width, other than the sp[ectator. Qualitatively we see a table such as.... Which brings to the hierarchy... Important is to assess whether Casc0 shorter lived than omegac

## c0 samples

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Finally, omegac. Mqss plot has 64 events, compared to 42 events from E687 and 40 from cleo Mass is right on pdg.

## c0 lifetime measurement

- Large corrections because of
-   loose detachement cut
- 3 fit parameters: **************B****************B******

**L(********c****0**** )= L(************ ******************** ************ ) x L(************ ************)**

**L/********>0**** **

**L/********>2**** **

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Lifetime is difficult because close to exptl resolution. F(t’) is flat for l/s>2 but very steep for >0 and that is were we need to work because short lifetime. Valu is 79 +-12 fs

## c0 lifetime systematics and result

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Systematics is under control  and total syst erro is 9 fs. Big improvement. Only two previous measurements of lifetimes, both of course at fixed target E687 photoprod and wa89 at cern adroprod. No cleoalthough thay observed 40 events and measured mass

## Results for Charm Baryons Lifetimes

**Results for Charm Baryons Lifetimes**

**PDG2002**
**FOCUS**
**FOCUS ****(not in PDG2002)**
**FOCUS ****preliminary**

******c****+**

******c****+**

******c****0**

******c****0**

**FOCUS significantly improved **
**the accurancy of  all charm **
**baryons lifetimes.**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Finally here is summary. Focus signficantly imporved... Cascc+/Lambda out ofpredictions or at least we need more precise predictions. Cascc0/omegac0 definievely >1, and more precise than models

## SEMILEPTONIC AND NONLEPTONIC  DECAYS

- SKIP SEMILEP

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
After having described results on lifetimes we step to study decay features. Focus has lots of new results on BR, but since I am running late already I’ll just talk about semileptonics

## A long-standing problem: the form factor ratios rv and r2 describing D+K0  should be close to Ds+ since only difference is a spectator
    quark d replaced with a s
Lattice gauge calculations:
    max diff= 10%
Experiment: 
 rv    OK
 r2  inconsistent (3.3.

-     quark d replaced with a s
- Lattice gauge calculations:
-     max diff= 10%
- Experiment:
-  rv    OK
-  r2  inconsistent (3.3.

- New measurements of the Ds+ form factor ratios **J.M.Link et al. (FOCUS Coll.) hep-ex/0401001 accepted by  Phys.Lett.B**

****

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Form factor formalism for Ds+ 

**D****s****+**

- s

- s

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Searching for s-wave interference in 

**K*******

- 

**data****ccbar mc**

- events cos **V**

- events cos **V**

- events cos **V**

- FOCUS published observation for a very strong s-wave interfering with p-wave in the K system for D  **K*******
- NO evidence for s-wave interference in Ds 

**data**

**K*******

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## The mKK distribution for   Ds+candidates

**Data (solid) and c****c**** background MonteCarlo (dashed). **
**Main background from**
**D****+********************where**
**a pion is misidentified as a muon**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## RESULTS

**r****v****=1.549 ± 0.250 ± 0.145**

**r****2****=0.713 ± 0.202 ± 0.266**

- Most precise measurement to date
- very consistent with D+K0
- very consistent with  expectation that the form
- factors for the two processes should be very similar

- Solid green: world av. Ds+ Dashed blue: world av. D+K0

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Form Factors D+K0  and Ds+ 

- THIS RESULT

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## DP analysis of Ds+ and D+ decay to  using the K-matrix formalism J.M.Link et al. (FOCUS Coll.) hep-ex/0312040 accepted by  Phys.Lett.B  see also : S.Malvezzi Workshop on B physics, Rome Italy January 15, 2004. 

- Dalitz plots have been proved to be a powerful tool in three-body decays, investigating
- Resonant substructure
- Interference patterns
- Final state interactions
- Relationships to light-meson spectroscopy
- Traditionally, isobar formalism used
- Decay amplitude is a sum of Breit-Wigner propagators
- Breit-Wigner amplitudes for a resonance which is broad and overlaps with other resonances can be connected to the pole positions only through models of analytic continuation

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## K-matrix picture

***K*****-matrix picture**

- The amplitude is written as a sum
- The amplitude F takes care of S-wave component by integrating over the scattering amplitudes of the five  virtual states K,’,

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## “K-matrix analysis of the 00++-wave in the mass region below 1900  MeV’’

**“****K-matrix analysis of the 00++-wave in the mass region below 1900  MeV’’**
-           V.V Anisovich and A.V.Sarantsev  Eur.Phys.J.A16 (2003) 229

** ****To describe the scattering a global fit  to all available**
** ****data was performed**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## FOCUS D s +  ++- analysis

- Yield Ds+ = 1475 50
- S/N Ds+ = 3.41

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## First fits to charm Dalitz plots

** ****in the *****K*****-matrix approach**

- C.L  fit 3 %

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## in charm hadronic decays 

**No significant direct three-body-decay component**

**No significant  ********(770) ******** contribution**

- Marginal role of annihilation
- in charm hadronic decays

**But need more data!**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

##  D+ ++- analysis   

- Yield D+ = 1527 51
- S/N  D+ = 3.64

-  D+ ++- analysis

- Sideband

- Signal

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## K-matrix fit results

- C.L fit 7.7 %

***K*****-matrix fit results**

- Low mass  projection

- High mass  projection

**No new resonance  required not present in the  scattering.**

**decay channel**** **

**phase (deg)**

**fit fractions (%)**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## BES 2004 (Zhu, LaThuile 04)

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## CONCLUSIONS (K-MATRIX)

- First DP analysis of Ds+,D**+******** ********+********+********-**** **charm decays using K-matrix formalism
- Use information from light-quark scattering experiments (five virtual channels considered K,’,CONCLUSIONS:
- Non-resonant components are described by known two-body S-wave dynamics
- Negligible role of annihilation diagram in Ds ****** ********+********+********–**** **
- Possible applications in B(not discussed here)
- DP analysis of Ds+,D**+******** ********+********+********-**** **charm decays using traditional isobar model is also in progress to compare to K-matrix model.

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## HOT PUZZLES IN SPECTROSCOPY

- Charmonium Spectroscopy
- CAVE:
- Lots of recent charmonium results from E835 (Patrignani’s talk)
- Focussing on experimental data, for a theory review see Barabanov’s talk
- No time to cover charmonium hadroproduction problem
- Ref.: excellent very recent reviews by V.Papadimitriou, C.Quigg LaThuile04
- L=1 Excited charm meson spectroscopy
- Exotica: doublecharm, c-5Q, etc etc

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## cc SPECTROSCOPY

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Long-standing puzzle I 

- On general grounds one expects
- This is what we get for pp, , etc but not for VP states such as
-  Q<0.23%, QK*+K-<0.64%,QK*0K0=(1.7+-0.6)% (BES 2000)
- More results shown at LaThuile 2004 (Zhu)
- Proposed explanations:
- Vector gluonium mixed with J/but not ‘ (Freund , Nambu 75)
- Large intrinsic c component in  (Brodsky Karliner 97)
- NRQCD, color octect (Chen, Braaten 98)

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

##  aka hc,      was claimed by R704 @ISR (1986)
Found by E760 @Tevatron (1993) Phys.Rev.Lett.69:2337-2340,1992

Not confirmed by E835 (2002)

- Found by E760 @Tevatron (1993) Phys.Rev.Lett.69:2337-2340,1992
- Not confirmed by E835 (2002)

**Long-standing puzzle II**** ****1P****1**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Conflicting results in the 80’s (DASP, Serpukhov, Mark II, Crystal B.)  
 c(2S) searched for by DELPHI and E835 and not confirmed
Spotted by BELLE (2002) in B decays PRL 89 (2002) 102001-1 and in the recoil spectrum of J/cc 

-  c(2S) searched for by DELPHI and E835 and not confirmed
- Spotted by BELLE (2002) in B decays PRL 89 (2002) 102001-1 and in the recoil spectrum of J/cc

**Long-standing puzzle III: ********c ****and**** ********c****(2S)**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## A somehow-newer puzzle J/cc

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

##  Discovered by BELLE in B decays
Confirmed by CDF and D0 at the Tevatron in pp collisions
A DD* bound state ?

- Confirmed by CDF and D0 at the Tevatron in pp collisions
- A DD* bound state ?

**A brand-new puzzle**** **X(3870)J/

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## hep-ex/0312021

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

- Moriond 2003

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## L=1 Excited Charmed Mesons

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Charmed mesons spectroscopy chart (ante Spring 2003)

- In the heavy-quark limit, the heavy-quark spin **S****Q**** ** and the total angular momentum  of the light-quark **j****q**=**L**+**S** are conserved

**PREDICTION #1:** Each level is composed  of a degenerate doublet of states with the same jq and total angular momentum J=jq± 1⁄2.
- jq=1⁄2 states are predicted  to be broad (100-200MeV width). **PREDICTION #2: **FLAVOUR SYMMETRY** **

**THIS PICTURE **
**QUESTIONED BY BABAR**
**AND CLEO DISCOVERY**
**OF Dsj. **

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## D*’    ENIGMA

- Observed by  DELPHI (P.Abreu et al, PLB426, 231 (1998)) e not confirmed either by CLEO nor  by OPAL.

- _1_
- 2

- ???

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## EVIDENCE OF  BROAD STATES

- Observations by CLEO, BELLE, FOCUS

- _1_
- 2

- CLEO 99

-  **hep-ex/0312060 **

-  **hep-ex/0307021 **

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## D and D* sample

**Processes studied:**
******N ******** D****0****************+ X,  **
**D****0********K******
**D****0******** K******
******N ******** D****+****************+ X, **
** ****D****+********K******
**Remove D******** combinations from D***

-  **hep-ex/0312060 **

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## D0and D+ mass distributions

- reconstruction

- M(D0+)-M(D0)+1.8646 (GeV/c2)

-   Shorthand: 

- Entries / 10 MeV/c2

- D0and D+ mass distributions

**Wrong sign**

- M(D+--)-M(D+)+1.8693 (GeV/c2)

- Entries / 10 MeV/c2

- Shorthand: 

**Wrong sign**

**Feed down from D****2*********, D****1**** partial **
**reconstruction**

**Combinatoric background**

-  **hep-ex/0312060 **

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## CDFGreatly improved charm physics capabilities with impact parameter trigger using silicon vertex detector. Nonetheless, huge comb. bkgr at primary vertex. Hadroproduction not the best place to look for L=1 excited D mesons

**CDF****Greatly improved charm physics capabilities with impact parameter trigger using silicon vertex detector. Nonetheless, huge comb. bkgr at primary vertex. ****Hadroproduction not the best place to look for L=1 excited D mesons**

- M.Shapiro, FPCP 2003 Paris

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## PRE-SPRING 2003

- The overall picture
- fairly well established,
-  with a few puzzles
-  remaining

- cu

- cs

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## DSJ OBSERVATIONS BY BABAR CLEO BELLE

- BABAR finds prominent narrow  resonance Dsj(2317)Ds+ 0
- CLEO finds prominent narrow resonance Dsj(2463)Ds*+ 0
-  BELLE finds evidence for Dsj(2463)Ds+ and determines JP=1+ for Dsj(2463)

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## DSJ OBSERVATIONS BY BABAR CLEO BELLE

- It seems natural to interpret Dsj(2317) and Dsj(2463) as
-  0+ and 1+ states, respectively;
- They are narrow because below the DK threshold, and therefore isospin-violating;
- Much lower mass than the 1+ (2535) and 2+ (2572) “narrow” partners;
- Where are the corresponding cu states (if flavour symmetry applies) ??? They should be lighter than Dsj(2317) and Dsj(2463).

**Bardeen Eichten Hill**
** ****hep-ph/0305049 :**
**Combine HQS and chiral invariance.**
** ****Form doublets (Ds,D*s) with **
**(D****s0+,****D****s1+****)**

**Can use this chart,**
**Just replace u********s**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## THE SELEX DOUBLECHARM BARYONS RIDDLE

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Double charm baryon search: +cc & ++cc

- Double charm baryon search: +cc & ++cc

- An extensive search was conducted in 2000 using:
**~20,000**** ********+****c******** ****pK******** ****+**** ****~1.2 million D****+,o ****(**** ****K********, K2********, K3******** )**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Dc comparison-efficiency

**FOCUS**** ****data for**** ****SELEX**** ****decay modes**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
FOCUS sees a lot more lambdac, factor of ten. Focus also has a cascc sigmac and omegac sample, selex did not show anything yet. If the signals reported are true, it has got to be a very peculiar production mechanism.

## Terra

**Charmonium Hybrids**
- well-suited for a hadron collider
**Charm Supernuclei**
- 	need very ambitious vertex detector

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## BREAKING NEWSH1 EVIDENCE FOR A CHARM 5Qhep-ex/0403017M=3099 ± 3 (stat.) ± 5 (syst.) MeVuuddc candidate

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## OUTLOOK AND CONCLUSIONS

-  Due to its unique production mechanism, PANDA will have leading role in
- cc spectroscopy;
- Charm quark in nuclear matter, charm hybrids;
-  and perhaps CPV,  but watch the competition by 2013 !

- Silver physics items:
- Leptonic and semileptonic decays (decay constants, formfactors, etc)
- Solving the puzzles in spectroscopy

- Golden physics items:
- New Physics in CP Violation asymmetries (or rare decays, not discussed here)

- Future charm experiments: COMPASS, BTEV, PANDA, SuperB-factories,...

-  Lots of new charm quark physics results from B-factories, BES, CLEO-c, FOCUS, CDF, D0, H1, ZEUS ...

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Finale

- All the Best, Pandas !

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## -------QUESTION SLIDES-----

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Models...HQS/HQET

- In the heavy-quark limit (mQ>>QCD) the heavy quark spin **S****Q**, the total angular momentum of the light quark **j****q**=**L+S****q** and the total angular momentum of the system **J = j****q**** + S****Q** are conserved

- Q

- q

- “The hydrogen atom of QCD”

**S****Q**

**S****q**

**L**

- As mQ increases the system properties are increasingly dominated by light quark dynamics.
- If mQ and mq >> QDC the system is described by a non-rel. Schrödinger equation with a generic two-body potential
- With
- 	 Vc = central potential + linear confining term
- 	 Vss = spin-spin potential + color hyperfine interaction (1/mQmq)
- 	 Vso = spin-orbit potential + color magnetic term (1/mQ,1/mq,1/mQmq)
- If mQ   the meson spectrum consists of degenerated spin doublets with:
- In heavy-light system states with J =1 can mix.

- V= Vc+Vss+Vso

- Topical issue:
-  Can HQS work with c-quark?

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
Da skippare

## Flashing on lattice QCD

- Reminder:
-  Calculation are performed in discrete space-time lattice: lattice spacing << 1/Mquark;
-  High computational requirements
-  In the case of one heavy quark the dynamics can by written in powers of 1/Mquark;
-  HQET help to reduce computational requirements (NRQDC);
- - NRQCD works well for bottom meson;

- Topical issues:
-  Is the charm mass heavy enough for NRQDC?
-  Again mass splittings between P-wave mesons?

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Synopsis of running and planned experiments

- Ref: D.Pedrini LEPTRE, Roma 2001

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## clipboard

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## D1 Cleo L. Rodriguez. HQF98

- Full partial wave analysis of the following decays:
- B  Dj
- Dj  D
- D  D

- -

- Good D1 narrow signal also seen in Focus

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

##                 Spectrometer at FERMILAB Wide Band Photon  Beam

**Successor to E687. Designed to study charm particles produced by ****~200 GeV photons**** using a fixed target spectrometer with updated  ****Vertexing,**** ****Cerenkov,**** ****EM **** ****Calorimeters,**** and ****Muon id**** capabilities.  Member groups from USA, Italy, Brazil, Mexico, Korea.        **_**DATA COLLECTED IN 1996-1997 **_

- Over 1 million reconstructed!

-                 Spectrometer at FERMILAB Wide Band Photon  Beam

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
But first  just a few general things about focus.  It ran in the 96 and 97 fnal fixed target run. We analyze the interactions of roughly 200 GeV photons which interact on a segmented BeO target which is roughly 12% of an interaction length.  The first part of our spectrometer consists of 4 planes of Si which are interleaved with the target segments and 12 planes of downstream Si. Charged tracks are momentum analyzed through a 2 magnet spectrometer and tracked by 20 PWC planes. We have ~300 cell threshold Cerenkov counter arranged in three counters (blue).  We also have excellent lepton identification for muon decays and electromagnetic calorimetry gives the ability to identify electrons and reconstruct photons and pizero. The apparatus is roughly  30 meters long.  We ran our beam very hot and accumulated a total charm sample of over 1 million fully  reconstructed Golden Mode charm events.

## Bibliography

- ICHEP02 Amsterdam
- S.Malvezzi *Mesons*
- C.Riccardi *Baryons*
- E.Gottschalk *Production Dynamics*
- FPCP02
- J.Wiss* Semileptonics*
- HQL2k2 Vietri
- L.Benussi *Spectroscopy*
- FCP01
- R.Kutschke* Spectroscopy*
- LEPTRE00 Roma
- D.Pedrini
- CICERONE

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## FOCUS Spectrometer

- Over 1 million reconstructed!!

- Successor to E687. Designed to study charm particles produced by ~200 GeV photons using a fixed target spectrometer with upgraded **Vertexing**, **Cerenkov**, **E+M Calorimetry**, and **Muon id** capabilities.  Includes groups from USA, Italy, Brazil, Mexico, Korea
**1 million charm particles reconstructed into D********K******** , K2******** , K3******

**FOCUS Spectrometer**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Baryon multiplets

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## SUMMARY AND CONCLUSIONS

-  New precise measurements of mass and widths of D2*+ and D2*0, with errors better than or equal to PDG03
-  Evidence for broad states in D+ and D0 final states
-  Puzzle of  Ds+****** ** form factors discrepancy solved with  new precise measurement
-  First DP analysis of Ds+,D**+******** ********+********+********-**** **charm decays using K-matrix formalism
- Use information from light-quark scattering experiments (five virtual channels considered K,’,CONCLUSIONS:
- Non-resonant components are described by known two-body S-wave dynamics
- Negligible role of annihilation diagram in Ds ****** ********+********+********–**** **
- Possible applications in B(not discussed here)
- DP analysis of Ds+,D**+******** ********+********+********-**** **charm decays using traditional isobar model is also in progress to compare to K-matrix model.

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Fitting D0and D+ mass distributions

- D-wave fixed
- to PDG D2* mass and
- width

- 2. D-wave free fit
- parameter

- Bad fits, excess
- of events between D2*
- and the feeddowns

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Fitting D0and D+ mass distributions

- Add S-wave
- Fit cl=22% now

- Recompute the
- feeddown lineshape
- using the D2* parameters
- measured in Step 3.
- Fit cl=28% now

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Significance of S-wave excess

- The broad excess observed could be the broad state D0*,
- or the feeddown from a broad D1 state        goto feedown list           .

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## RESULTS

|  | D2*0 | D2*+ | D2*+-D2*0 | “D01/2” | “D+1/2” |
| --- | --- | --- | --- | --- | --- |
| Yield | 5776±869±696 | 3474±670±656 |  | 9810 ± 2657 | 18754±2189 |
| Mass
PDG03
BELLE03 | 2464.5±1.1±1.9
2458.9±2.0
2461.6± 3.9 | 2467.6±1.5±0.76
2459±4 | 3.1±1.9±0.9
0 ± 3.3 | 2407±21±35

2308± 36
 | 2403±14±35 |
| Width
PDG03
BELLE03 | 38.7±5.3±2.9
23±5
45.6± 8.0
 | 34.1±6.5±4.2
25+8-7 |  | 240±55±59

276±66 
 | 283±24±34 |

- Errors on D2* masses and widths smaller than or equal to PDG03
- Agreement with the recent BELLE result (hep-ex/0307021).

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## SYSTEMATICS STUDIES I

|  | D2*0
 |  | D2*+ |  | D2*+-D2*0 | “D01/2 “ |  | “D+1/2” |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | Mass | Width | Mass | Width | Mass | Mass | Width | Mass | Width |
| L/< 30 | 0.160 | 1.231 | 0.134 | 0.960 | 0.294 | 0.926 | 15.73 | 0.050 | 2.871 |
| Part/Antipart | 1.67 | 0 | 0.53 | 0 | 0 | 0 | 0 | 0 | 31.4 |
| PD < 70GeV/c | 0.227 | 0.705 | 0.392 | 1.983 | 0.165 | 2.482 | 8.509 | 10.38 | 2.500 |
| Different Fits | 0.412 | 0.272 | 0.124 | 0.693 | 0.353 | 10.48 | 43.95 | 1.439 | 8.635 |
| Fit Regions | 0.376 | 0.536 | 0.174 | 0.991 | 0.315 | 1.571 | 12.80 | 1.209 | 6.657 |
| Feed-down tests | 0.633 | 2.373 | 0.262 | 3.289 | 0.443 | 32.71 | 31.91 | 32.45 | 6.137 |
| Binning tests | 0.442 | 0.576 | 0.113 | 0.770 | 0.550 | 6.584 | 6.652 | 6.380 | 0.894 |
| Mass Scale | 0.100 | 0 | 0.100 | 0 | 0.100 | 0.100 | 0 | 0.100 | 0 |
| Total syst. error | 1.94 | 2.89 | 0.76 | 4.2 | 0.91 | 35.1 | 59.0 | 34.7 | 34.0 |

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## SYSTEMATICS  STUDIES II

- Background shapes:
-                                   (E687)
-                                              (L3)

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## THIS RESULT AND THEORY PREDICTIONSPredicted mass differences with respect to the D meson compared to this result

| Reference | D2*
jq = 3/2
3P2 | D1
jq = 3/2
3P1 | D1
jq = 1/2
1P1 | D0*
jq = 1/2
3P0 |
| --- | --- | --- | --- | --- |
| This paper | 599 ± 2 |  |  | 538 ± 39 |
| World Av. | 593 ± 3 | 556 ± 4 |  |  |
| Kalashnikova et al. (2002) | 579 | 562 | 603 | 564 |
| Di Pierro et al. (2001) | 592 | 549 | 622 | 509 |
| Ebert et al. (1998) | 584 | 539 | 626 | 563 |
| Isgur (1998) | 594 | 549 | 719 | 699 |
| Godfrey and Kokoski (1991) | 620 | 590 | 580 | 520 |
| Godfrey and Isgur (1985) | 620 | 610 | 560 | 520 |
| Eichten et al. (1980) | 645 | 637 | 498 | 489 |
| Barbieri et al. (1976) | 428 | 380 | 339 | 259 |
| De Rujula et al. (1976)  | 494 | 464 | 384 | 374 |

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

## Levels Splitting (I)

-  L = 1 between c and light quark (u,d,s)
-  jlight = Slight + L: is approximately good Q number if mc >> QCD
-  Idealized picture is a “doublet of doublet”

- No spin

-  > mc >> QCD

- mc 

| Jq | JP | Decays |  (MeV/c2) | Observed | Decay |
| --- | --- | --- | --- | --- | --- |
| 3/2 | 2+ | D*, D |  20 |  | 1+3/2  D-wave |
| 3/2 | 1+ | D* |  20 |  |  |
|  |  |  |  |  |  |
| 1/2 | 1+ | D* |  100 | New results | 1+1/2  S-wave
 |
| 1/2 | 0+ | D |  100 |  |  |

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
How do we compare results to theory. Not a simple matter. In the limit of Mc infinite there would be two levels, but since mc not infinite this splits into four. Predictions are often not usable since there is no error to levels. Experiment in this case is much more precise than models.

## Levels Splitting (II)

- ...mQ is not infinite: working with the real mass causes the P-wave states to overlap. But:
- 	- The L= 1 states pattern is not univocally described by models.
- 	- The choice of potential is crucial.

- Doublets of doublets...But what happen in real life?

- 2

- 1

- 1

- 0

- 2

- 1

- 1

- 0

- J = 2

- J = 1

- J = 1

- J = 0

- Ebert

- Di Pierro

- Lewis Woloshyn (lattice)

- Kalashnikova (lattice)

- J = 2

- J = 1

- J = 1

- J = 0

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004

**Notes:**
The only reasonable thing to do is to compare the pattern of multiplet shifts between theory and data. Dipierro seems to do a good job ?????
Additional issue is mixing between doublets.
? Check? and this conlcudes spectroscopy

## Processes studied:
N  D0+ X,  D0K-,K-
N  D++ X,  D+K-
Feeddowns:
D1+(jq=3/2)D*0,  D*0D
D2*+D*0,  D*0D
D1+(jq=1/2)D*0,  D*0D

- N  D0+ X,  D0K-,K-
- N  D++ X,  D+K-
- Feeddowns:
- D1+(jq=3/2)D*0,  D*0D
- D2*+D*0,  D*0D
- D1+(jq=1/2)D*0,  D*0D

- Measurement of masses and widths of excitedcharm mesons, and evidence for broad states**J.M.Link et al. (FOCUS Coll.) hep-ex/0312060 accepted by  Phys.Lett.B**

- Stefano Bianco - Hot Topics in Charm Physics - PANDA Workshop at Frascati

- March 18th, 2004