flavour opportunities at the intensity frontier · flavour opportunities at the intensity frontier...

Flavour Opportunities at the Intensity Frontier

Luca SilvestriniINFN, Rome

● Introduction● Where we stand and where we are heading to in flavour physics

● Future scenarios & interplay with LHC● Conclusions

Luca Silvestrini ICFA, SLAC, 29/10/2008

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


INTRODUCTION - II

Two accidental symmetries of the SM are crucial for our discussion:1) Absence of tree-level flavour changing neutral currents, GIM suppression of FCNC @ the loop level

2) No CP violation @ tree level Flavour physics extremely sensitive to NP!!


EXPRESS REVIEW OF THE SM • All flavour violation from charged current

coupling: CKM matrix V

• Top quark exchange dominates FCNC loops: third row (Vtq) determines FCNC's

V CKM=1−

2

2 A

3−i

− 1−

2

2A

2

A31−−i −A

2 1O

4

_ _


BR(bul), BR(Bl)

mq (Bq-Bq mass diff.)

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

ACP(bsss, dds) ( K, K, ...)

ACP(bddd, uud) (, )

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

BR(B)

BR(B)/BR(B)

K

K+

Flavour summarized on the plane

_

_

_ _

_ _

CC

NC

CC

NC

CC/NC

CC

CC

NC

NC

NC

_


Where we stand: UTA & NP in F=2

Consider ratios of (SM+NP)/SM F=2 amplitudes

Determine C's and 's using generalized UT analysis

Derive bounds on NP scale and/or couplings


Our present knowledge:


SUMMARY OF CONSTRAINTS

No deviation seen in K physics, slight tension in phaseof Bd mixing, ample room for NP in phase of Bs mixing(might become solid evidence w. Tevatron & LHCb)


Ratio of NP/SM contributions is < 40% @ 95% prob.in Bd mixing, and ~60% in Bs mixing (but compatible with zero at 2).


THE SCALE OF NP

• The constraints we obtained can be used to put lower bounds on the scale of NP models with a given flavour structure:

• Ki numeric coefficient of O(1), Fi flavour structure, L loop coefficient, NP scale

ANP/ASM ~C/CSM


BOUNDS ON THE NP SCALE

To be relevant for the hierarchy problem, NP must have a highly nontrivial flavour structure!!


Two broad flavour scenarios1) Minimal Flavour Violation (i.e. no new

source of flavour violation beyond Yukawa couplings) effectively holds at least at the level seen in K and Bd mixing, i.e. < 40%.

2) New sources of Flavour & CPV are at work in transitions between 2nd and 3rd families, but strongly suppressed elsewhere. Nonabelian flavour symmetries? Guts + ?

Tevatron and LHCb will tell us soon!


What we are aiming at

• Being able to determine the flavour structure of whatever NP seen at the LHC

• Being able to derive info on the full spectrum of NP if LHC only sees part of it

• Being able to cover indirectly the region of NP masses just above the LHC reach, pushing the indirect bound on as high as possible


How do we get there - I

• A few % error on CKM parameters in the generalized UTA;

• Determining NP contributions to F=2 and F=1 transitions in all sectors (K, Bd, Bs, D) at the few percent level;

• Improving Lepton Flavour Violation and Lepton Universality bounds by more than one order of magnitude


How do we get there - II

• CKM parameters in the presence of loop-mediated NP: Vcb,ub

incl,excl, (BDK)

• NP contributions to F=2 amplitudes: (bccs), s(bccs), D0ASL

d,s, ()d,s


How do we get there - III• NP contributions to F=1 amplitudes:

• bs: (BSSSS,...), BsK*0K*0 (penguins), BK(*) (penguins & ewp), BXs(ewp) BXs

(BR&ACP) (photon peng), BXsll (BR&AFB) (photon & ewp), (B Ks

) (RH ops), Bs(scalar peng)

• bd: B(ewp) BXd(ewp) BXd

(BR&ACP) (photon peng), BXdll (BR&AFB) (photon & ewp), S(B ) (RH ops), Bd(scalar peng)

• sd: KLK+(ewp) KLll (photon & ewp)


How do we get there - IV

• LFV: ee(photon peng), llell eee, e (photon, ewp & boxes), e (photon, ewp, boxes & Higgs)

• Lepton Universality: KeKBB(Higgs)

• Charged current scalar interactions: B(Higgs)


+ FC physics (CPV, ... )

B physics @(4S)

B physics @(5S)

Charmphysics

physics

K physicsKe/K @ @ 10-12

Experimental...


no theoryimprovements

needed

improvedlattice QCD

improvedOPE+HQE

improvedQCDF or SCET

or flavour symmetries

or data drivenmethods

(J/ K), (DK), ,lepton FV & UV,

CPV in B->X, D and decays,zero of FB asymmetry B->Xsl+l-

meson mixing , B->D(*)l,B->()l,B->K*, B->, B->lBs->

B->Xu,cl

S's from TD ACP

in b -> s transitions

SM already knownwith the required accuracy

target error: ~1-2%Feasible (see SuperB CDR)

target error: ~2-3%Feasible getting exp. rid of

annihilation & shape function(see arXiv:0810.1312)

target error: ~2-3%need either breakthrough

in computing power corrections or data-driven approaches (Dalitz analyses

particularly favourable)

...and theoretical efforts needed!


FUTURE SCENARIOS AND COMPLEMENTARITY W. LHC


Let's begin with the worst case...

• Let's assume that LHC finds the Higgs and nothing else (including no deviation in Bs mixing).

• Were naturalness arguments wrong or is the Higgs sector just a bit fine-tuned?

• Flavour physics gives us the chance to reach for higher scales!


The basic step: CKM matrix at the %

U. Haisch, Kaon '07erro

r bu

dget

KL -> π0 ν ν_

“the dream” “the nightmare”

today SuperB

0.177±0.044 1±0.005 0.360±0.031 ±0.005

Generalized UT fits:CKM at % in thepresence of NP! Will detect deviations from the SM at the level of 3% in CBd and of 0.5° in Bd


The NP reach we can obtain depends on the NP flavour structure:

• MFV SUSY @ small tan: won't go beyond the TeV region, although bswill cut a lot

• MFV SUSY @ large tan: can reach several TeV's with Bl:

2HDMIIMSSM

SuperB CDR


The situation improvesconsiderably if newsources of FV are present: can reach3 evidence for gluinomasses up to 10 TeV for maximal b-d squark mixing, and gobeyond the TeV forCabibbo-like mixings.

SuperB CDR


The case of WED

• Warped extra dimensions/minimal composite Higgs could solve the hierarchy problem and explain SM flavour structure via fermion localization/degree of compositeness

• However they generate chirality-flipping contributions to F=2 amplitudes at tree level very strong constraints from K


Csaki et al. '08; Buras et al. '08;Agashe et al. '08

A moderately fine-tuned WED model should lieabove the LHC reach, but should give visible effects in flavour physics at the few % level (K, S(KS), ...).


A less pessimistic scenario...

• Let's assume that ATLAS and CMS see some good candidates for SUSY particles.

• We should try and reconstruct the whole SUSY Lagrangian, but probably we won't know the whole spectrum and most probably we won't be able to measure flavour couplings at high-pt


Reconstructing LSUSY

(Some of the) Diagonal sfermion masses will be measured@ LHC; off-diagonal terms to be determined from flavour(relevant parameters: (d

ij)AB= (dij)AB/(mii)AA(mjj)BB)


Reconstructing (d13)LL=0.085 ei/4 and (d

23)LR=0.028 ei/4 for mSUSY=1TeV

SuperB CDR


• For a full reconstruction of the hadronic part of the SUSY Lagrangian, need % knowledge of meson mixings (including D) and FCNC decays

• Agreement with the SM as useful as disagreement

• If deviation from SM in Bs confirmed, effort in measuring bs decays mandatory

• Notice that a large b s mixing could invalidate standard LHC strategies to search for SUSY Flavour @ LHC Workshop, arXiv:0801.1800

~ ~


Lepton Flavour Violation● For slepton masses in the LHC range LFV becomes extremely interesting!● In SUSY-GUTs:

● can identify the neutrino Yukawa flavour structure (CKM or PMNS) by studying & ;

● interesting correlations with bs transitions● Interesting correlations also in MFV case:

LFV from PMNS

LFV from CKM

Isidori, 4th SuperB workshop


LFV in an SO(10) SUSY-GUT

Calibbi et al. 06

liljll and liljP useful to constrain Higgs and box contributions


OVERALL SUSY ASSESSMENT• Combining high-pt and flavour data we can

constrain LSUSY and thus get hints on:• the SUSY-breaking mediation mechanism• the flavour breaking mechanism• the underlying presence of a GUT structure• the origin of neutrino mixing Okada et al. '07

p large deviation expected

● detectable deviation possible


An optimistic scenario...

• Let's assume extra dimensions are seen at the LHC

• For warped extra dimensions this implies some mechanism to suppress tree-level contribution to K

• Improved precision on flavour physics necessary to establish flavour structure and identify suppression mechanism

Fitzpatrick et al '07; Cacciapaglia et al. '07;Santiago '08; Csaki et al. '08;


The nonperturbative scenario...• Let's assume there is no Higgs and nothing

else to unitarize WW scattering at 1 TeV• Perturbative unitarity of weak interactions

is lost: electroweak chiral Lagrangian, Technicolour and all that...

• “Not calculable or, when calculable, incompatible with electroweak data”

• Not much can be said except that great fun would be guaranteed in all sectors!

Barbieri '08


CONCLUSIONS: PRESENT

• Present status: control CKM + NP F=2 at the 20-30% level, except for Bs mixing where O(1) NP is favoured

• Bounds on NP scale tell us that NP can be within the LHC reach only if

• it is MFV-like within at most 40% or• it contributes O(1) to b s and <40% elsewhere


CONCLUSIONS: FUTURE• Control CKM + NP in F=1,2 at the % level;

push down searches for LFV by two orders of magnitude or lower; improve tests of LU

• Ensure determination of flavour structure of whatever NP seen at the LHC

• Ensure sensitivity to moderately fine-tuned NP above the LHC reach

• Requires covering the full spectrum of B(s), D, K and LFV observables


BACKUP SLIDES


- lattice QCD can reach the O(1%) precision goal in time- extrapolation assuming no improvement in algorithms, just increase in computing power

V. Lubicz,4th SuperBWorkshop

andSuperB

CDR


The importance of gathering 75 ab-1


Okada et al '07


F. Mescia @ FPCP08


Proceedings of Superb VI, arXiv:0810.1312

Luca Silvestrini ICFA, SLAC, 29/10/2008Proceedings of Superb VI, arXiv:0810.1312


Results for a “typical” flavour configuration withsizable mixings and splittings. Many experimental strategies affected: e.g. g->bbj->bb

k, t->+1b

~ ~ ~ ~ ~_ _

flavour opportunities at the intensity frontier · flavour opportunities at the intensity frontier...

Documents