Views on Flavour Physics Opening Talk, DAFNE 2004Laboratori Nazionali dell’ INFN di Frascati, June 9, 2004.

Luciano Maiani, Universita’ di Roma La Sapienza.

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 2

Collider energies versus time

~~

GeV

?

AdAVEP-1

CBXACO

ADONECEA

SPEAR

VEPP-2

DORIS

PETRA

CESRVEPP-4

PEP TRISTANLEP

SLCHERA

LEP2

DCI

LHC

SppS TEVATRON

ISR

LHC

RHIC

KEK-B

PEP2

DAFNE

BEPC

0.1

1

10

100

1000

10000

100000

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

e+ e- colliders

P-P, P-P-bar colliders

ions

Flavour Physics

Meson Factories

•BNL (muon g-2)•SPS (NA48)•....

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 3

SUMMARY

• The muon g-2

• Semileptonic decays and CKM unitarity

• A fresh look at the scalar mesons

• Flavour physics: why continue?

Very personal viewsNot systematic at allApologies for omissions!

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 4

Brookhaven National LabMuon g-2 Collaboration(Y. Semertzidis, ICHEP 2002)

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 5

BNL, Muon g-2 Collaboration, 2004Positive and negative muons combined

Electroweak:

=

Light-by-light:

Hadron (CMD2+KLOE):

Total SM:

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 6

Comparison CMD2-KLOE

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 7

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 8

g-2, conclusions

• The discrepancy is 3, but huge, 2 x electroweak: improving on the error is mandatory and crucial;

• The bad guy is light-by-light scattering: no perspective (at the moment) to get a “rigorous” estimate,

• Nonetheless, an error of 4 10-10 is most likely conservative

• It leaves margin to improvement by a factor 2-3 on the present error

• More effort on R (at higher energy in particular) is justified

• As well as another round of g-2 experiment at Brookhaven!!

• The result may have fundamental implications on the planning of the next HE machine, beyond the LHC, with very low cost !

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 9

Unitarity of the weak mixing matrix

•Superallowed beta transitions in I=1, 0+ nuclei•Neutron beta decay:

•Contribution of Vub is negligible•Cabibbo unitarity leads to the prediction :

Gino IsidoriWorkshop on the CKM Unitarity Triangle, IPPP Durham, April 2003arXiv:hep-ph/0311044, Nov 2003.

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 10

KLOE, 2004

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 11

Hyperon decays: NA48 data!

New!!! KTeV (KLl3):

[(KS)e3]

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 12

CKM Unitarity (conclusions)

• Isospin and SU(3) breaking seems to be under control with Chiral Perturbation Theory;

• There is still some margin for improvement, to 0.1% errors (?)

• A remarkable achievement.

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 13

Exotic Baryon States

T. Nakano et al.. hep-ex/0301020 Jul 2003 Evidence for Narrow S=+1 Baryon Resonance in Photo-production from Neutron

V.V. Barmina et al.. hep-ex/0304040 Sep 2003 Observation of a baryon resonance with positive strangeness in K+ collisions with Xe nuclei.

S. Stepanyan et al. hep-ex/0307018. Dec 2003Observation of an Exotic S = +1 Baryon in Exclusive Photoproduction from the Deuteron

NA49 Collaboration hep-ex/0310014 Oct 2003Observation of an Exotic S = -2, Q = -2 Baryon Resonance in Proton-Proton Collisions at the CERN SPS

+

- -

Spring-8, JP

ITEP(RS)LNF(IT)

Jeff. Lab, US

CERN

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 14

+ was predicted in Skyrmion model (SU3 decuplet)…what about quark model?Bound-diquark idea revisited by Jaffe & Wilczeck[qq]

is a boson![qq]+[qq] are in L=1 (at short distance they remember of fermionic constituents)

[qq]+[qq]+q-bar= )2/1J,810,0(q]qq[]qq[ Pflavourcolour

)0spin,3,3(]qq[ flavourcolour21

Bound diquarks [qq]?

Roper resonance ?

Are there mesons ?flavour

)18(]qq][qq[

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 15

-The a(980)I=1 and f(980)I=0 fit very well in the diquark picture

A fresh look at the light scalar mesons

])ds][sd[]us][su([2

1f];ds][su[a

- almost degenerate (m= 10-20 MeV) - a(980) decays in states with one strange quark pair ();To complete 8+1 we need:

The first is (480), claimed by many groups, seen well by KLOE in fWith (480) and a(980) we find (quadratic masses) m~770 MeV. The kappa is missing for the moment. A strange particle like this has been claimed.... it badly needs confirmation.

]us][ud[];du][ud[ 0

Antisymmetric diquark explains inverted properties w.r.t. vector mesons: the isolated I=0 is the lightest state and likes to decay in !.

Work in progress (L.M., A. Polosa, F. Piccinini, V. Riquer)

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 16

M=

Study of the Decay with the KLOE DetectorThe KLOE CollaborationarXiv:hep-ex/0204013 Apr 2002

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However, from time to time :

The potential barrier becomes finite (if it exists at all!) and tunneling towards an outgoing pair of qqbar mesons is possible.The swich is described by a single amplitude, A.

For (480), and a(980), with A= 2.6 GeV, we find:345MeV, a= 43MeV,.....not too bad!

The switch amplitude brings

which is below threshold. Rescattering can bring to .

scalar meson decays

.glsin.col.glsin.col )du()ss(]ds][su[

Diquarks are color triplets, they cannot be separated!

K*f(980)

K

K-bar

Switch amplitude makes contact with K-Kbar molecule, but physics is different !

...KK...])sd)(ds()su)(us[(2

1])ds][sd[]us][su([

2

1f

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 18

Hidden charm:

charmonium octet(??)+singlet . Possible decays:

Open charm:

Really spectacular signatures.

Heavy flavours

KK,)DD()0I(f

)1I(a

?thresholdbelowc

cc

MD63]qq][cq[

18]qc][cq[

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 19

states (conclusions)

• Many open questions on scalar low energy mesons:• Consistent widths

• Can we obtain a consistent picture of Scalar + • To clarify the issue of themay be very useful

• Search of the• Narrow states are seen by BABAR, CLEO and BELLE in charm

containing hadrons: similar explanations?

• Other exotic states have been considered in the past:– Gluon balls

– Hybrid (gluons +quarks)

– qq-qbar qbar

• A rich spectroscopy at low energy, to be tested in heavy flavour systems.

]qq][qq[

Singlets are very difficult

No real motivation

Exotic baryons exist. Good signals:octets, inverted spectrum, ..

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 20

•In a way, it is a trivial question…CERN’s future is the LHC:–Commissioning 2007;

–Physics: 2007- 2022 (at least);

–Consolidation programme

–Luminosity upgrade can prolong LHC lifetime and extend its discovery potential by 15-30% in mass;

–Energy upgrading rather costly and further in the future, as it requires the development of new high field magnets (Nb3Sn?15 Tesla ? ).

}Some resources available in CERN plan.

•However:–Important HEP physics problems and corresponding scientific communities are not addressed by the LHC–Diversification is needed–e+ e - Linear Collider (subTeV): TESLA/NLC/JLC ?–Discussion must start now

Views for the Future of CERNSymposium to celebrate the discoveries of Neutral Currents (1973) and of W&Z (1983)CERN, Geneva, September 16, 2003

DAFNE04. June 9, 2004 L. Maiani. Views on Flavour Phyisics 21

Flavour Physics: why continue?

• Flavour Physics is very well (surprisingly!) alive• Time is ripe to decide how to continue: high luminosity at ,

charm, B-factories?• This Conference is timely and important: we need to know more

and better.• My personal view:

– The LHC is coming soon, but the next HEP machine is not behind the corner;

– keeping intermediate scale projects is important;– Flavour and neutrino physics projects have just the right size....– And a very, very rich physics.

GO FOR IT !