flavour opportunities at the intensity frontier · flavour opportunities at the intensity frontier...
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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 Page 2ICFA, 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
Luca Silvestrini Page 3ICFA, SLAC, 29/10/2008
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!!
Luca Silvestrini Page 4ICFA, SLAC, 29/10/2008
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
_ _
Luca Silvestrini Page 5ICFA, SLAC, 29/10/2008
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
_
Luca Silvestrini Page 6ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 7ICFA, SLAC, 29/10/2008
Our present knowledge:
Luca Silvestrini Page 8ICFA, SLAC, 29/10/2008
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)
Luca Silvestrini Page 9ICFA, SLAC, 29/10/2008
Ratio of NP/SM contributions is < 40% @ 95% prob.in Bd mixing, and ~60% in Bs mixing (but compatible with zero at 2).
Luca Silvestrini Page 10ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 11ICFA, SLAC, 29/10/2008
BOUNDS ON THE NP SCALE
To be relevant for the hierarchy problem, NP must have a highly nontrivial flavour structure!!
Luca Silvestrini Page 12ICFA, SLAC, 29/10/2008
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!
Luca Silvestrini Page 13ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 14ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 15ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 16ICFA, SLAC, 29/10/2008
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)
Luca Silvestrini Page 17ICFA, SLAC, 29/10/2008
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)
Luca Silvestrini Page 18ICFA, SLAC, 29/10/2008
+ FC physics (CPV, ... )
B physics @(4S)
B physics @(5S)
Charmphysics
physics
K physicsKe/K @ @ 10-12
Experimental...
Luca Silvestrini Page 19ICFA, SLAC, 29/10/2008
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!
Luca Silvestrini Page 20ICFA, SLAC, 29/10/2008
FUTURE SCENARIOS AND COMPLEMENTARITY W. LHC
Luca Silvestrini Page 21ICFA, SLAC, 29/10/2008
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!
Luca Silvestrini Page 22ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 23ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 24ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 25ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 26ICFA, SLAC, 29/10/2008
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), ...).
Luca Silvestrini Page 27ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 28ICFA, SLAC, 29/10/2008
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)
Luca Silvestrini Page 29ICFA, SLAC, 29/10/2008
Reconstructing (d13)LL=0.085 ei/4 and (d
23)LR=0.028 ei/4 for mSUSY=1TeV
SuperB CDR
Luca Silvestrini Page 30ICFA, SLAC, 29/10/2008
• 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
~ ~
Luca Silvestrini Page 31ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 32ICFA, SLAC, 29/10/2008
LFV in an SO(10) SUSY-GUT
Calibbi et al. 06
liljll and liljP useful to constrain Higgs and box contributions
Luca Silvestrini Page 33ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 34ICFA, SLAC, 29/10/2008
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;
Luca Silvestrini Page 35ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 36ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 37ICFA, SLAC, 29/10/2008
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
Luca Silvestrini Page 38ICFA, SLAC, 29/10/2008
BACKUP SLIDES
Luca Silvestrini Page 39ICFA, SLAC, 29/10/2008
- 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
Luca Silvestrini Page 40ICFA, SLAC, 29/10/2008
The importance of gathering 75 ab-1
Luca Silvestrini Page 41ICFA, SLAC, 29/10/2008
Okada et al '07
Luca Silvestrini Page 42ICFA, SLAC, 29/10/2008
Okada et al '07
Luca Silvestrini Page 43ICFA, SLAC, 29/10/2008
Okada et al '07
Luca Silvestrini Page 44ICFA, SLAC, 29/10/2008
Okada et al '07
Luca Silvestrini Page 45ICFA, SLAC, 29/10/2008
F. Mescia @ FPCP08
Luca Silvestrini Page 46ICFA, SLAC, 29/10/2008
F. Mescia @ FPCP08
Luca Silvestrini Page 47ICFA, SLAC, 29/10/2008
Proceedings of Superb VI, arXiv:0810.1312
Luca Silvestrini Page 48ICFA, SLAC, 29/10/2008Proceedings of Superb VI, arXiv:0810.1312
Luca Silvestrini Page 49ICFA, SLAC, 29/10/2008
Results for a “typical” flavour configuration withsizable mixings and splittings. Many experimental strategies affected: e.g. g->bbj->bb
k, t->+1b
~ ~ ~ ~ ~_ _