Flavour Physics - Istituto Nazionale di Fisica Nucleareifae2006/talks/Plenarie/Silvestrini.pdf ·...

Luca Silvestrini Page 1IFAE, 21/4/2006

Flavour Physics Stefano Giagu & Luca Silvestrini

Introduction Recent experimental & theoretical developments:

Kaon physics (M. Dreucci, P. Massarotti)B physics (P. Gambino, T. Cartaro, N. Neri, E. Baracchini, M. Morello)BS,C physics (P. Santorelli, R. Ferrandes, G. Salamanna, G. Passaleva)

Impact on the SM and beyond: Unitarity triangle analysis in the SM and beyond (V. Vagnoni) Constraints on SUSY parameters (V. Porretti, P. Paradisi)ConclusionsOutlook: the role of flavour physics in the era of LHC


INTRODUCTION The Standard Model works beautifully up to a few hundred GeV's, but it must be an effective theory valid up to a scale Λ Mplanck:

EW scale

Has accidental symmetries

Violates accidental symmetries


How can we explore NP with processes involving only SM particles?

I. Electroweak gauge symmetry spontaneously broken tree-level relations between EW observables (masses, couplings, ...)

quantum corrections computable and sensitive to higher-dim operators

The LEP glorious legacy of precision EW fits: Λ > 2-10 TeV!!

HOW TO PROBE NEW PHYSICS:I. ELECTROWEAK SYMMETRY BREAKING


Three flavours of fermions with same gauge quantum numbers but different mass.

Flavour eigenstates are not weak interaction eigenstates weak interactions change flavour

Accidental symmetry of the SM: Neutral current weak interactions conserve flavour at the tree level, GIM suppression of loop contributions

quantum corrections computable and sensitive to higher-dim operators

FLAVOUR & CP VIOLATION IN THE SMHOW TO PROBE NEW PHYSICS:

II. FLAVOUR PHYSICS


• All flavour violation from charged current coupling: CKM matrix V

• and A from CC decays – tree-level, SM• Top quark exchange dominates FCNC loops:

third row (Vtq) determines FCNC's sensitive to new physics

V CKM= 1−2

2 A3−i

− 1−2

2A2

A31−−i −A2 1O 4

_ _


Error anatomy of BRγ

Total error 8% dominated by charm mass Can be partially resolved by NNLO

Misiak, PG 2001

mc enters the phase factordue to normalization

= 0.581±0.017

and the NLO matrix elements

Misiak & PG

Talk by P. Gambino


NNLO status report

Misiak, Moriond 2006


Forward-Backward asymmetry in B K* l+ l-


Babar:

Belle:


Talk by M. Morello


Talk by N. Neri


Talk by M. Morello


A handle on non-factorizing BS decays using SU(3)

Talk by R. Ferrandes


R. Ferrandes


Bc decays in a quark model

P. Santorelli

Luca Silvestrini Page 23IFAE, 21/4/2006 P. Santorelli

Luca Silvestrini Page 24IFAE, 21/4/2006Talk by G. Salamanna

Luca Silvestrini Page 25IFAE, 21/4/2006 G. Salamanna


From UTfit:


BR(bcl), BR(BD(*)l)

BR(bul), BR(Bl)

md, md/ms

ACP(bccs) (J/ K, ...)

ACP(bddd, uud) (, )

BR(bcud, cus) (DK, ...)

BR(B)

BR(B)/BR(B)

K (CP violation in K mixing)

Flavour summarized on the plane

_

_

_ _

CC

CC

NC

CC

CC/NC

CC

CC

NC

NC

_


Using:md, ms, |Vub/Vcb|, sin 2CP violation in B mixing (new from BaBar):

PRELIMINARYAccuracy comparableto the SM fit!


C=1.15±0.13[0.97,1.55]SM: C=1

CBd=1.38±0.45[0.69,2.54]

d [°]=-4.0±2.2[-8.2,0.8]

Get a nonvanishing Bd because of SMfit discrepancyCBs now constrained by msBs still unconstrained

PRELIMINARY


N. Neri


THE MSSM

• In the MSSM, two classes of contributions to FCNC's:● Supersymmetrization of SM contributions (W w, t t) + H

● pure SUSY contributions: g – q • second class requires new sources of flavour

violation in squark mass matrices

~ ~

~ ~

Hall, Kostelecky & Raby; Gabbiani et al.


A Model-Independent Analysis

• We consider a MSSM with generic soft SUSY-breaking terms, but– dominant gluino contributions only– mass insertion approximation

four insertions AB=LL, LR, RL, RRNow full NLO available!

d Ai d B

jδd ij AB

Talk by V. Porretti

Think of 's as SUSYequivalent of CKM mixing


CONSTRAINTS ON 's• contribute to Kaon mixing:

constraints from ΔmK & εK• contribute to B mixing:

constraints from ΔmB & sin2β

• contribute to Bs mixing and b s decays: constraints from ΔmBs, b s, b sl+l-

• for reference, choose mgl=msq=350 GeV

δd 12 ABδd 13AB

δd 23 AB


THE SUSY FLAVOUR PROBLEM

• Strong constraints on SUSY breaking mechanism:–Flavour-universal breaking?–Flavour symmetry?


Talk by F. Mescia


LHCb performance with 2fb-1 (1 year)

C7eff/C9eff with 13% errorNP search

σ(ACPdir) ≈ 0.01

σ(sin2β) ≈ 0.022

0.01 ps-1

σ(φs) ≈ 2°

σ(α) ≈ 10°

σ(γ) ≈ 14°

σ(γ) ≈ 6°

σ(γ) ≈ 8°

σ(γ) ≈ 5°

Precision

σ(sin2β) ≈ 0.018

CDF17.33±0.35 ps-1

σ(α) ≈ 7-15°

σ(γ) ≈ 6.5°

B-factories 2ab-1

0.8216kBd → J/ΨKSβ


LHC performance after 5 years

After 5 years: σ SM expectation

φs(Bs→ ccss) ~0.013 ∼0.035

Br(Bs→ µ+µ−) ~0.7×10−9 ~3.5×10−9

γ (DsK, DK) ~1° ~60° (tree only) γ (ΚΚ+ππ) ~2° ~60° (tree + penguin)

Talk by G. Passaleva


CONCLUSIONS• Recent data from B-factories and the Tevatron

close the possibility of order-of-magnitude NP effects.

• New sources of CPV can still be present in b->s transitions: need LHCb + superB.

• In a few years, will constrain NP at the 10% level in all sectors. Theoretical accuracy approaching the SM one.

• Flavour problem open: still miss explanation of flavour structure (and of apparent MFV)


THE ROLE OF FLAVOUR PHYSICS IN THE LHC ERA

• Most probably see some NP at LHC, but not the full spectrum of NP particles;

• Even if full spectrum seen, still many parameters to be determined;–Need flavour physics as much as LC

• Flavour remains the most powerful probe of scales higher than the reach of LHC


EXAMPLE I: LFV @ LARGE tan


EXAMPLE II: SUSY-GUTs

• In an SU(5)-like GUT, quark and leptons are unified, so also squark and sleptons.

• After running down to weak scale, one has:

• Correlations between quark & lepton FCNC!


Im (d23)RR vs. Re (d23)RR

any BR τ μγ

m q=m g350 GeV

BR τ μγ 6⋅10−7

BR τ μγ 1⋅10−7 BR τ μγ 1⋅10−8

Ciuchini et al, PRL


Flavour physics in the LHC era will play a leading role in determining the relevant NP

model parameters, in exploring higher energies and in providing us with clues on the

physics at MGUT.

Flavour Physics - Istituto Nazionale di Fisica Nucleareifae2006/talks/Plenarie/Silvestrini.pdf ·...

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