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Deciphering new physics with B decays

杨亚东 华中师范大学粒子所

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1. OvertureA precision B physics era yet:BABAR @SLACBELLE@KEKD0, CDF@Tevatron@FermiLab

• Decays at Br~10-5 precisely measured (if PID of the final states is easy )• So many measurements• So many interesting topics

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Overture: 10 years B factories

2010.6

Already 1000M data

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Super B

Discovery of CPV in B decay

Precise test of KM(CPV) and SM

Search/Evidence for New Physics

Step1

Step2

Step3

2001 summer !

Hints for NP ?

2008

Need >1012 B data(L ~1036cm-2s-1 )

Now: ~10 years of B-factories BaBar & Belle

LHCb

Overture: experimental map

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LHCb is already there

Overture: Another 10 golden years

✔ Belle II @ KEK will taking data in 2014

✔ SuperB @ Cabbibo Inst. has been approved very recently by Italy governmentL ~1036cm-2s-1 luminosity frontier can probe New Physics at scale much higher than 14TeV

Quest for CPV Quest for New Physics

The transition :

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2. Deciphering NP with Flavor Physics

Borrow fromBuras

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NP scenarios dancing with PenguinsTheir flavor structures, parameter spaces, new particles are constrained very much by Penguin processes

viaFCNC

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B PhysicsSo far, confirmed success of the CKM picture of Flavor Changing Neutral Current of GIM picture

✔ Leave “small room” for New Physics? or NP should be Minimal Flavor Violating (MFV)?

✔ “Small room” will grow to be very significant, given measurement precision improved much.

✔Strongly correlated with direct search at CMS&ATLAS “DNA” test the possible New Physics scenarios.

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3. An example: Top FCNC v.s b→sγ✔ Strongly GIM suppressed in the SM✔ t→cγ, cZ clean signals✔ Sensitive to New Physics

For a review: Beneke et al., hep-ph/0003033

✔ 5σ discovery limits for t→cγ :

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The anomalous top couplings Model independently, for on-shell gauge bosons,

Γ(t→cγ)=

Very tiny NLO QCD corrections[J.J.Zhang, C.S.Li, J.Gao, Z.Li, C.P. Yuan, T.C. Yuan,PRL102(2009)072001]

There are many studies in the specified models, C.H. Chang, C.S.Huang,X.Q. Li,J.X.Wang, M.Z.Yang PLB313(1993)389 W.G. Ma, J.M.Yang, X.L. Wang et al.

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The anomalous t-c-γ couplings

Actually, the decay will involve two independentoperators

As chirality flipped, an explicated quark mass factor must be there with the two operators.

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Its effects in b→sγ decays

If the anomalous t-c-γ coupling exits, it will affectthe precisely measured b→sγ decays, thus toughconstraints

HFAG10

The NLO result in the SM [A.J. Buras, et al., NPB631(2002)219 ]

Very good agreement!

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The penguin diagram

(a) dominated

For (a) t-c-γ dominated

And, compared with (c ), there is a Vcs/Vts enhancement,So it is very sensitive to the strength of t-c-γ coupling

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The result

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Constraints The running down to mb is the same as the SM since there is no new operators for b→sγ decay appeared.

We ask

σexp

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The dependence of B(B → Xsγ) (×10-4)on the κtc/Λ

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The remained parameter space

If the anomalous coupling is real,i.e. no electroweak phase, the constraint is tough

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The corresponding upper limits on B(t→ c γ)

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The correlations:

B(t→ c γ) <5.2 x 10-4 for κtcR>0

B(t→ c γ) <6.8 x 10-4 for κtcR<0

which are slightly higher than the 5σ discovery requirements of ATLAS & CMS

which would be inaccessible at LHC in the first few years running at 14TeV !

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HyperCP[PRL94(05)021801]

First evidence forThree events for dimuon invariant mass: M=241.3±0.5MeV

Trigger lots of studies on what is the P0?

X.G et al., suggest P0 is A01--the light CP-odd Higgs

in the Next-to-MSSM.

2nd example: A very light CP odd Higgs?

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BaBar and CELO made searches for Υ(3S) → γA → γ l+l- Υ(1S) → γA → γ +invisible

We combine all the measurements and the g-2of muon to constrain the light CP-odd Higgs,to see if it can survive

• Theoretically, there are lots of interests for mA<2mb [Gunion et al.]

Direct Search and Theoretical Studies

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The rare decay π0→e+e-

Very old story since the 1st paper by S.Drell [Nuovo Cimento XI(1959)693 ]

It is hindered by the structure dependent of

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The leading diagram in the SM

The normalization of

is known from π0→γγ. Thus the imaginary of amplitude can be obtained model independently.

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Recent improvement

Using a dispersive approach to the amplitudeand the exp results of CLEO for

π-γγ* form factor, Dorokhov and Ivanov have found:

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The NMSSM

extend MSSM by a new Higgs singlet superfieldS to solve the known fine tuning problem

κ measures the size of Peccei-Quinn symmetry breaking

H± + three scalars h0, H01,2

+pseudoscalars A01,2

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If the PQ symmetry is broken slightly, A01 can be rather light

We use

Which can be related to NMSSM, but not a must

So our following constraints can apply to any light pseudo scalar “Higgs”

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Constraints

1. on the scenario of

KTeV

CLEO

BaBar

So, this scenario is excluded

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Maybe we need another confirmation of theHyperCP measurement.

At least, P0 can not be the A01 in NMSSM

Now, we turned to constrain the relevant parameter space

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We perform a scan with

and

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Case A: assuming A01 soley responsible for

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Case-B: assuming A01 contribution smaller than 1σ

error-bar of

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Unexpectly, it pionts to

When

, and it’s width is very narrow, so mA is very sensitive to the peak

Amazing !

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3. The resonant effects of

The mixing angle

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The mass eigenstates are obtained as

The decay amplitude of the “physical” state

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Combing the constraints from and

We get

very similar to the ones with Breit-Wigner formula.

The mixing angle is found to be

So far, so good. It would be very exotic if we have a light “Higgs” degenerated with π0 !

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It’s natural to ask ：Can π0 →γγ toleratesuch a “Higgs”?

With and

to give

it will demand a too large value

Thus, such a case is excluded.

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Conclusion of this example:

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Since there is no parameter space for mA1< 2mb

survived the combined bounds, such a “interesting” window is closed. there is still no answer for the HyperCP 3 dimuon

events if it were confirmed with refinedmeasurements.

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1989-1999: HQET [Isgur,Wise,Gerogi,Bj, Grinstein,……. ]

4. Brief overview of Theory

We know the normalization of form factor at zero recoil from QCD, and a clear picture of heavy meson

1999-2009 [QCD Factorization:Beneke, Buchalla,Neubert Sachrajda ]

Factorization proved, 2-loop correction finished [SCET-Bauer, Piorj] Factorization proved to all orders of QCD [pQCD: H.n.Li, A.Sanda, C.D.Lu, M.Z.Yang+….]

Not yet. Partial 1-loop corrections. So far so good

For B decays

2009- today: Not available yet

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Comparison: QCDF-pQCD-SCETpQCDQCDFSCET

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Theory: A long way to go

There are known knowns-------- gains; There are known unknowns----- defects; Any movement would be greatly appreciated It is highly nontrivial Remind: the simplest pion form factor

But we have to pay these defects to face LHb, Super KEKB

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For the effective Hamiltonian

1988-2010: up to 2-loop EW+QCD 22 years hard work of A.J. Buras and his

students! [The story is summarized in arXiv: 1102.5650] Deserve a big prize: 21250 citations

Recently, Buras group has moved to “DNA” test of new physics models with the well establish measurements from Belle, BaBar……..

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The pursue of NP by Buras team

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Recent entertainment with my students1. Model independent probe of NP effects

Qin Chang, Xinqiang Li, YD, JHEP 0706 (2007) 038, JHEP 0809 (2008) 038Xinbo Yuan, Yang Hao, YD, PRD83(2011)013004Xinqiang Li, Xinbo Yuan, YD，JHEP 1108 (2011) 075

2. Model dependent probe of NP effects (SUSY, Z’ )J.Wang, Y.G.Xu, R.M.Wang, YD, PRD77 (2008) 014017Q.Chang, YD, PLB676 (2009) 88; NPB852 (2011) 539R.M. Wang, YD, PRD79 (2009) 055004Y.G.Xu, R.M. Wang, YD, PRD79 (2009) 095017; PRD83 (2011) 095010Q.Chang, X.Q. Li, YD, JHEP 0905 (2009) 056; JHEP 1002 (2010) 082; JHEP 1004 (2010) 052 Int.J.Mod.Phys. A26 (2011) 1273

3. Heavy Quark Spin SymmetryX.Q.Li, Fang Su, YD, Phys.Rev. D83 (2011) 054019

Many thanks to my young collaborators.

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5. Summary Before we have direct evidence for New

Physics, we are constraining NP(John Ellis) With data from SuperB, LHCb, one can

decipher flavor structure of possible NPs. New theory framework is badly wanted to

match the experimental precision By product, many unexpected hadron states Another 10 golden years of B physics with LHCb, SuperB, Belle II.

Quest for New Physics

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Which guy is the promised? Who will fly?

Thank you !