near-term prospect of b physics y. kwon (yonsei univ.)

Near-term ProspectNear-term Prospectof B physics

Y. Kwon (Yonsei Univ.)

What I said in FPCP2003, to announce “FPCP2004 in Korea”...

and, this might be the sort that the organizers had in mindunder the subject “near-term prospect”...

overlaps... unavoidableoverlaps... unavoidable With so many good talks in B physics at this

conference; on both present & future – “Agent Provocateur” on hot topics – “CKM summary”– “New physics in B decays”– “Super B Factories”– as well as prospects for B physics @ hadron machines– and all the excellent experimental result talks

It’s very hard to avoid much overlaps... if I want to give a standardized talks on “Near-term prospect”

So, I will just focus on personal favorites which I want/expect to see in B physics in the near future

And, this talk will in no way be theoretical

ProloguePrologue Tomorrow (Oct.9) used to be a national holiday,

in celebration of the invention of “Han-gul” (Korean alphabet system); a very successful system esp. in the modern digital era

It was a national project initiated (and finished) by the Great King Sejong in 15th C.

Before Han-gul, Koreans did not have its own alphabets, but borrowed Chinese characters for writing; not a very convenient choice, because they are two totally different languages

The best thing King Sejong did was to have thought differently; instead of imitating Chinese characters, Han-gul was based on 28 (now 24) character elements that have one-to-one (and onto) correspondence to phonetic sounds in Korean

““Think different!”Think different!” During the last decade (plus more), everyone

worked real hard in an anticipation of great things to come – preparing for the B-factories

And now, we are all enjoying a great success of B physics – in both experiment & theory

The next obvious path will be “Super-B”, but... Realistically, we still have a formidable task of convincing the tax-payers for one“Great, you now have your CP violations. Congratulations on a great job well ‘done’!”

So, we should not be afraid of searching for “crazy” things

ContentsContents CPV & CKM Rare B – esp. in leptonic modes

– overlapping w/ my own talk here on Monday will be very brief

Personal list– Distributions– Ordinary, but missing modes– Never ignore “crazy” modes

What do we expect in a What do we expect in a few years?few years?

Obviously, statistics will increase– Let’s aim at 1/ab per each B-factory– i.e. approx. factor 4 from current sample– stat. err. ~½ x (now)

Better understanding of generic B & charm decays– some analyses are (somewhat) limited by

background systematics– help from CLEO-c & BES?

Improved theory– L-QCD– Other improvements

And a few surprises, hopely...

-- by the time LHC turns on

Obviously, statistics will increase– Let’s aim at 1/ab per each B-factory– i.e. approx. factor 4 from current sample– stat. err. ~½ x (now)

Better understanding of generic B & charm decays– some analyses are (somewhat) limited by

background systematics– help from CLEO-c & BES?

Improved theory– L-QCD– Other improvements

And a few surprises, hopely...

What do we expect in a What do we expect in a few years?few years?-- by the time LHC turns on

Once upon a time, there Once upon a time, there was LEPwas LEP

What to anticipateWhat to anticipatein CP violationin CP violation

- still, mostly stat.-limited

BB00 and and 22(())

Milky Way

Babar New!

We hope to see this being resolved...We hope to see this being resolved...

Belle vs. BaBar on Belle vs. BaBar on 33 (Dalitz)(Dalitz)

new

CPV of non-CKM typesCPV of non-CKM types

CPV in di-leptons (++ CPV in di-leptons (++ vs. --)vs. --)

~ O(10-3) in the SM

)%56.060.013.0(

NNNN

0028.00030.00006.1 pq 85M BB

biggest syst. err. from track selection and continuum subtraction

B B X Xsstruly amazing progress in ~10 years

CLEO 1993

Belle 2003

CPV in b CPV in b ss

CPV in b CPV in b ss

CP asymmetry in B CP asymmetry in B XXss CP asymmetry is expected to be small (<1%) in SM some non-SM models allow large (~10%) ACP without changing the BF possible contamination from Xd (ACP can be large)

but negligible in the current measurements

152M BB89M BB

015.0050.0025.0)( sbACP

030.0050.0002.0)( sbACP

CKM sideCKM side- esp. Vub

VVubub from inclusive B from inclusive B XXuu l l

Using full-recon. tagging

The lesson: no single dominant error, i.e. need to beat down every error sourcestat. / background / shape / theory, etc.

VVubub from exclusive B from exclusive B XXuu l l

all about tagging ...

VVubub from exclusive B from exclusive B XXuu l l

VVubub using using ll w/ high-q w/ high-q2 2 & L-& L-QCDQCD

The error is dominated by exp. stat. and L-QCD error a good sign, isn’t it?

2 4 BaBar: LCSR, low-q2

Belle: L-QCD, high-q2

Shape Shape functionfunction

made possible by E spectrum in b s

a theorist’s a theorist’s call ...call ...In an illuminating talk by Bigi

yesterday,

Rare B decaysRare B decays- B l () modes - B Xd

B B l l ( ())Mode BF (SM) BF (Expt.)

B ~ 10-4< 2.9x10-4 (Belle,

prelim.)< 3.3x10-4 (BaBar)

B ~ 5x10-7< 2.0x10-6 (Belle,

prelim.)< 6.6x10-6 (BaBar)

B (2~5)x10-6

< 2.3x10-5 (Belle, prelim.)

B e < 2.2x10-5 (Belle, prelim.)

Grinstein, FPCP2004 : “Double Ratio”

B B X Xdd

How about then ? )/()()/()(

*

*

KDDKBB

2tdts /VV

Distributions that Distributions that we needwe need

or to watch out ...

Important Important distributionsdistributions q2 in exclusive B Xu l q2 in B Xs l+l- (excl. & incl.) AFB(q2) in B Xs l+l- E in B Xs

etc.

Background errors are Background errors are

not negligible, eithernot negligible, either

What shall we do?

Do we understand b Do we understand b c ? c ?

Flavor-specific inclusive K using K-lepton corr.

Original motivation (Kagan, ’97) was to look for excess prompt Kaon from b sg type decays

In interpretation, we were not sure whether we understand Kaon yield from b c s

We have to find out “missing modes” ...

Belle-Conf-0126 (submitted to LP-01)

A new tool to explore A new tool to explore missing modesmissing modes

Full-recon. tagging is so powerful to constrain the kinematics of signal B

Then, why don’t we apply it to explore b c modes that have not (or poorly) been measured because of missing neutrinos?

(Ex1)(Ex1) BBDD l l with full with full recon.recon.

Exclusive B SL decays in PDG2004

nothing much is known except for D and D*

Exclusive measurements w/ B/B ~ O(10%) are feasible

(Ex2)(Ex2) flavor-specific flavor-specific inclusive inclusive

Never forget “crazy” Never forget “crazy” modesmodes

We should not regret for not having tried...

(Ex)(Ex) “ “Neutrinoless 2Neutrinoless 2 decay” in B?decay” in B?

CLEO

SummarySummary Went through a list of subjects which

might be interesting in a near-future in B physics– Belle vs. BaBar : TCPV in B0 + -

– Belle & BaBar vs. SM : TCPV in b s vs. b c Many potentially interesting

measurements are still stat.-limited, but...– For some parameters, esp. Vub, we do not

have much budget for error in any source– Details, e.g. background understanding shall

be important explore missing, ordinary modes

We shall never give up searching for “crazy” things