scouting for new physics ( using charged leptons ) Jure Zupan u. - - PowerPoint PPT Presentation

scouting for new physics
 ( using charged leptons )

1

Jure Zupan

• u. of cincinnati

CLFV, Charlottesville, VA, June 20 2016

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

why new physics?

• many of the questions in particle physics may require new physics
• NP can be at very different scales
• weak scale (WIMPS, weak scale SUSY…)
• GUT scale (right handed neutrinos, extra gauge bosons,…)
• very light (axions, dark photons,…)

2

DARK MATTER Baryogenesis? Leptogenesis? Hierarchy
 problem Naturalness cosmological constant S M f l a v

• r

p u z z l e quantum gravity

neutrino masses

• eyp. anonalies

strong CP
 problem

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

which scale?

• for the Higgs mass we had unitarity bounds, mh≲1TeV
• no such precise statement about the next scale
• naturalness/hierarchy problem an important

guidance

• but not bullet proof
• cLFV probes of new physics
• can probe high scales
• if new particles are discovered, complementary

information to high pT searches

3

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

naturalness

• the naturalness problem
• large MPl - weak scale hierarchy
• what sequesters mh from MPl?

4

t

t ~

+

• the problem with naturalness
• how much fine-tunning is too much?


100000000000000000000000000000000.00TeV2


• 99999999999999999999999999999999.99TeV2


=(0.1TeV)2

radiative 
 corrections bare
 mass

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

naturalness

• the naturalness problem
• large MPl - weak scale hierarchy
• what sequesters mh from MPl?

5

t

t ~

+

• the problem with naturalness
• how much fine-tunning is too much?


1.00TeV2


• .99TeV2


=(0.1TeV)2

radiative 
 corrections bare
 mass

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

naturalness

• the naturalness problem
• large MPl - weak scale hierarchy
• what sequesters mh from MPl?

6

t

t ~

+

• the problem with naturalness
• how much fine-tunning is too much?


100.00TeV2


• 99.99TeV2


=(0.1TeV)2

radiative 
 corrections bare
 mass

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

naturalness

• the naturalness problem
• large MPl - weak scale hierarchy
• what sequesters mh from MPl?

7

t

t ~

+

• the problem with naturalness
• how much fine-tunning is too much?


10000.00TeV2


• 9999.99TeV2


=(0.1TeV)2

radiative 
 corrections bare
 mass

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

why charged leptons?

• theoretically simpler than hadrons
• can make very precise measurements
• many different probes

8

h→τµ, τe µ→3e B, Bs decays B→Dτυ h→μe τ→μγ, eγ k a

• n

d e c a y s μ→e conv.

lepton universality

electsoo EDM

μeγ

τ→μ+hadr.

muon g-2

high pT FV

τ → 3 μ , 3 e

• elec. g-2

MUON EDM

neutrinoless 2β decay

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

sensitivity

• cLFV very high reach in NP scale
• depends on the chiral/Lorentz structure of NP operators
• several low eng. measrm.nts ⇒ nontrivial info. about NP

9 Cirigliano, Ramsey-Musolf, 1304.0017

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

why so sensitive?

• the flavor structure in the SM is special
• gauge invariance ⇒ lepton universality in couplings to Z, γ
• GIM cancellation leads to very suppressed FCNCs in the νSM
• LFV established in neutrino oscillations ⇒ cLFV generated at

least at loop level

• due to GIM mechanism vanishingly small

10

PMNS unitary, U"i*Uei =0 
 ⇒ the piece indep. of 
 mν cancels

Br(µ → eγ) = 3α 32π

• X

i

U ∗

µiUei

m2

νi

m2

W

• 2

∼ 10−54

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

charged leptons vs. quarks

• compare with quarks
• GIM mechanism less effective
• not a zero theory (“SM background” free) search


• for cFLV as soon as signal found it means NP
• i.e. NP beyond νSM (=SM+ dim5 op. for neutrino

masses)


11

Br(µ → eγ) = 3α 32π

• X

i

U ∗

µiUei

m2

νi

m2

W

• 2

∼ 10−54

Br(b ! sγ) ' 6α π

• V ∗

tsVtb

Vcb f(mt/mW , αS)

• 2

!NNLO QCD (3.36 ± 0.23) ⇥ 10−4

Asatrian et al., 1503.01789

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...
• if neutrinos Majorana, their masses from

dim 5 Weinberg operator
 


• requires new particles that couple to leptons
• in general new sources of flavor violation

beyond PMNS

• can enhance cFLV to observable levels

charged leptons and neutrinos

12

Cij (HLi)(HLj) Λ

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

see saw models

• 3 tree level see-saw models to generate

Majorana neutrino masses

13 Hambye, talk at 1st CLFV, Lecce, 2013

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

distinguishing see-saw models

• all three see-saw models lead to the same Weinberg
• perator


• impossible to distinguish the models from neutrino
• scillation data alone
• need extra input
• production of extra states at the LHC if scale low enough
• from cLFV processes also for high scales, if Yukawas

large enough

• note: different combinations of FV couplings enter the cFLV

processes and the Weinberg operator

14

Cij (HLi)(HLj) Λ

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

type I see-saw

• for instance in type I see saw 


(with quasi-degenerate Ni)
 
 


• using (approximate) symmetries possible to have large

cLFV and small neutrino masses

• for quasi-degenerate Ni to a good extend the product of

Yukawas cancel in ratios of cLFV processes
 


• can probe scale of mN from "→e conversion

15

Γ(µ → eγ) ∝ 1 m4

N

X

Ni

• YNieY †

Niµ

• 2

Chu, Dhen, Hambye, 1107.1589;
 Alonso, Dhen, Gavela, Hambye, 1209.2679;

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

type I see-saw

• for instance in type I see saw 


(with quasi-degenerate Ni)
 
 


• using (approximate) symmetries possible to have large

cLFV and small neutrino masses

• for quasi-degenerate Ni to a good extend the product of

Yukawas cancel in ratios of cLFV processes
 


• can probe scale of mN from "→e conversion

15

Γ(µ → eγ) ∝ 1 m4

N

X

Ni

• YNieY †

Niµ

• 2

Hambye, talk at 1st CLFV, Lecce, 2013 Chu, Dhen, Hambye, 1107.1589;
 Alonso, Dhen, Gavela, Hambye, 1209.2679;

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

singling out the right new physics model

• more generally, the pattern of observed

cLFV processes can point to which NP

16 Buras, Duling, Feldmann, Heidsieck, Promberger, 1006.5356

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

examining the higgs

• another case in point : flavor properties
• f the Higgs

17

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

higgs

• two main questions about the Higgs
• responsible for electroweak symmetry breaking?
• from couplings to Z, W ⇒ predominant

source of EWSB

• does it give the dominant contrib. to quark and

lepton masses?

• here precision low eng. measurements with

charged leptons very important

18

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...
• generation of masses in the SM through the Higgs

mechanism

• implies Higgs 


has hierarchical
 couplings to 
 fermions

• in the SM
• can it be modified 


by NP?

• how well have 


we tested this?

higgs = nontrivial flavor structure

19 plot due to E. Stamou

yf = √ 2mf/v

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

testing the flavor of the higgs

• how well have we tested the flavor of the Higgs?
• several questions
• proportionality?

• factor of 


proportionality?


• diagonality?

• reality? 


(CP conserving?)

20 Perez, Soreq, Stamou, Tobioka, 1503.00290

ySM

f

= √ 2mf/v

yii ∝ mi

yii/mi = √ 2/v

yij = 0, i 6= j

Nir, 1605.00433

arg(yij) = 0

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

how large?

• two important questions
• how large are Yij assuming EFT?
• how large can Yij be in reasonable

models?

21

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

CPV and FV higgs couplings to SM fermions

• if SM an EFT, the Yukawas get corrected by higher dim. ops


• decouples mass terms from yukawas


• can lead to flavor violating Higgs decays
• can lead to CPV Higgs decays
• different models lead to different patterns of flavor

diagonal and flavor violating Yukawas

22

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

summary of models

• an example: higgs couplings to 2nd&3rd
• gen. charged leptons

23 adapted from Dery, Efrati, Hochberg, Nir, 1302.3229 and extended; see also Bishara, Brod, Uttayarat, JZ, 1504.04022

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

experimental constraints

• what are present experimental constraints?
• right now can address
• are diagonal Yukawas hierarchical?
• are they CP violating?
• are there FV Yukawas?
• the notation


• focus on charged leptons

24

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

hierarchical yukawas?

• proportionality for 3rd generation?


• top quark yukawa most precise 


indirectly through loops

• Yb and Yτ could still be equal
• hierarchical among generations?
• i.e., are 1

st and 2 nd generation 


Yukawas smaller than 3

rd gen.?

• only established for leptons 


25

yii ∝ mi Ye, Yµ ⌧ Yτ

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

CPV electron yukawa?

• κ

̃ e≠0 induces electron EDM

• dominant contributions at 2-loop


• experimental bound


• for c0=i ⇒ M > 1000 TeV
• compare with

26 Altmannshofer, Brod, Schmaltz, 1503.04830 ACME coll., 1310.7534

|˜ κe| < 1.7 × 10−2

p |κe|2 + |˜ κe|2 < 611

CMS-HIG-13-007

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

CPV coupling to τ

• impressive improvement in el. EDM is projected
• 3 orders of magnitude
• in the plot no direct CPV measnt. at the LHC is assumed
• O(0.2) measrmnt. on κ

̃ τ maybe possible (at LHC 3 ab-1)

27 Harnik, Martin, Okui, Primulando, Yu, 1308.1094 Brod, Haisch, JZ, 1310.1385

Higgs and beyond, Pitt, Dec 4 2015

• J. Zupan Higgs and flavor

see also Blankenburg, Ellis, Isidori, 1202.5704

h→τ"

• bounds from
• τ→"γ
• τ→3"
• muon g-2
• muon EDM
• Br(h→τ")~O(10%) 


allowed

28 Harnik, Kopp, JZ, 1209.1397

Higgs and beyond, Pitt, Dec 4 2015

• J. Zupan Higgs and flavor

see also Blankenburg, Ellis, Isidori, 1202.5704

h→τ"

• bounds from
• τ→"γ
• τ→3"
• muon g-2
• muon EDM
• Br(h→τ")~O(10%) 


allowed

28 Harnik, Kopp, JZ, 1209.1397

10-3 10-2 10-1 100 10-3 10-2 10-1 100 »Y mt» »Y tm» t Æ mg t Æ 3m Happrox .L H g

• 2

Lm + E D M m

H g

• 2

L

m

û I m H Y

t m

Y

m t

L = » Y

t m

Y

m t

» = m

m

m

t

ê v

2

Our LHC lim it

HATLAS 7 TeV, 4.7 fb -1L

BRHh ÆtmL = 0.99 10-3 10-2 10-1 0.5 0.75

Harnik, Kopp, JZ, 1209.1397

Higgs and beyond, Pitt, Dec 4 2015

• J. Zupan Higgs and flavor

see also Blankenburg, Ellis, Isidori, 1202.5704

h→τ"

• bounds from
• τ→"γ
• τ→3"
• muon g-2
• muon EDM
• Br(h→τ")~O(10%) 


allowed

28 Harnik, Kopp, JZ, 1209.1397

10-3 10-2 10-1 100 10-3 10-2 10-1 100 »Y mt» »Y tm» t Æ mg t Æ 3m Happrox .L H g

• 2

Lm + E D M m

H g

• 2

L

m

û I m H Y

t m

Y

m t

L = » Y

t m

Y

m t

» = m

m

m

t

ê v

2

Our LHC lim it

HATLAS 7 TeV, 4.7 fb -1L

BRHh ÆtmL = 0.99 10-3 10-2 10-1 0.5 0.75

Harnik, Kopp, JZ, 1209.1397

Higgs and beyond, Pitt, Dec 4 2015

• J. Zupan Higgs and flavor

Harnik, Kopp, JZ, 1209.1397

h→τe, h→"e

29

Higgs and beyond, Pitt, Dec 4 2015

• J. Zupan Higgs and flavor

Harnik, Kopp, JZ, 1209.1397

h→τe, h→"e

29

Higgs and beyond, Pitt, Dec 4 2015

• J. Zupan Higgs and flavor

Harnik, Kopp, JZ, 1209.1397

h→τe, h→"e

29

room for a discovery

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

flavor violating higgs decays?

• CMS [ATLAS] at 8 TeV observes hint of a

signal at 2.4 [1]σ 
 


• first 13 TeV analysis (CMS)
• does not exclude 8TeV
• a hint of a signal?

30 CMS-HIG-14-005 ATLAS, 1508.03372, 1604.07730 talk by María Cepeda at Higgs Tasting, 
 May 2016, Benasque, Spain

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

τ→"##

• hadronic tau decays τ→"(+(-,τ→"(0(0
• sensitive to both Yτ","τ and


light quark yukawas Yu,d,s

• Yu,d,s poorly bounded ~O(Yb)
• for Yu,d,s at their SM values then


• for Yu,d,s at their present upper bounds


• Br(τ→"(+(-) below present exp. limit, if discovered


would (among other things) imply upper limit on Yu,d

• similarly pseudoscalar Higgses can be bounded from τ→"((η,η’), τ→e((η,η’)
• can saturate present experimental limits

31 reinterpreting Celis, Cirigliano, Passemar, 1309.3564; see also Petrov, Zhuridov, 1308.6561

Br(τ → eπ+π−) < 4.3 × 10−7, Br(τ → eπ0π0) < 2.1 × 10−7

Br(τ → eπ+π−) < 2.3 × 10−10, Br(τ → eπ0π0) < 6.9 × 10−11

Br(τ → µπ+π−) < 1.6 × 10−11, Br(τ → µπ0π0) < 4.6 × 10−12 Br(τ → µπ+π−) < 3.0 × 10−8, Br(τ → µπ0π0) < 1.5 × 10−8

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

correlated bounds

• "→eγ and "→e conversion constrain also the products of off-

diagonal tau Yukawas

• setting Y"e and Ye" to zero one has


• one then has a constraint on FV Higgs decay Br’s


• ⇒ if Br(h→τ") is at the CMS central value, then Br(h→τe)<25%
• improving "→e conversion can have a big effect

32 Dorsner, Fajfer, Greljo, Kamenik, Kosnik, Nisandzic, 1502.07784

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

large fv higgs decays?

• Can one have large flavor violating

Higgs decays in 
 reasonable NP 
 models?

• What is so special 


about type III 
 2HDM?

33 Dorsner et al., 1502.07784

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

large fv

• a generic obstacle to large h→τ" is the bound on τ→"γ
• improvement on Br(τ→"γ) can have a big impact
• same diagrams that generate fermion masses (higgs

yukawas) also give τ→"γ
 
 
 
 
 
 


34 Altmannshofer, Gori, Kagan, Silvestrini, JZ, 1507.07927

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

large fv

• a viable set of models
• decouple fermion mass generation from τ→"γ
• possible if new source of EWSB
• for instance if our higgs only responsible for tau mass
• e.g. in 2HDM


• but could also be other sources of mass (TC,..)

35

Ml=

φ’ φ and φ’

Altmannshofer, Gori, Kagan, Silvestrini, JZ, 1507.07927

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

phenomenological implications

• Bs→"" can be modified by O(1)
• sizable Bs→τ", B→Kτ", B→K*τ"
• anomalies could be seen in 


Bs mixing, τ → "γ, b → sγ

• leptonic heavy Higgs (H) decays 


to "" dominate over ττ

• opposite to Type-II 2HDMs
• lower bound on H→τ"

36 Altmannshofer, Gori, Kagan, Silvestrini, JZ, to appear Efrati, Kamenik, Nir, 
 work in progress

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

750 GeV

• other NP states can have nontrivial flavor

interactions

• e.g. 750 GeV di-photon
• right now preference 


for couplings to heavy 
 quarks of gluons

• flavor violating decays 

• f S severely constrained

37 Kamenik, Safdi, Soreq, JZ, 1603.06566

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

750 GeV

• other NP states can have nontrivial flavor

interactions

• e.g. 750 GeV di-photon
• right now preference 


for couplings to heavy 
 quarks of gluons

• flavor violating decays 

• f S severely constrained

37 Kamenik, Safdi, Soreq, JZ, 1603.06566 Goertz, Kamenik, Katz, Nardecchia, 1512.08500

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

take home message #1

• there is complementarity between cLFV

and high pT searches for New Physics

• they measure orthogonal properties

38 Grossman, Ligeti, Nir, 0904.4262 /cLFV see also Galon, Shadmi, 1108.2220

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

take home message #2

• cLFV signals could come from unexpected NP corners
• example: relaxion mechanism to make EW scale technically natural

through cosmological evolution

• some concrete realizations require extra Z2 odd charged leptons
• if any mixing with SM leptons ⇒ cLFV

39 Gupta et al., 1509.00047

large couplings, low mass scale

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

take home message #3

• cLFV can probe high scale
• examples mini-split SUSY
• O(1-10TeV) gauginos at LHC or future collider; PeV sfermions

from low energy precision probes

40 see also McKeen, Pospelov, Ritz, 1303.1172 Altmannshofer,Harnik, JZ, 1308.3653

Now

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

take home message #3

• and will improve dramatically in the

future

41 see also McKeen, Pospelov, Ritz, 1303.1172 Altmannshofer,Harnik, JZ, 1308.3653

Now Future

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

conclusions

• cLFV searches are an indispensable part
• f particle physicist’s toolkit
• shown examples where cLFV probe see-

saw models, Higgs Yukawas, PeV SUSY, 750 GeV scalar..

• the discovery may well be in an

unexpected corner of NP model space

42

backup slides

43

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

for light quark yukawa couplings

• several indirect probes of 1st and 2nd

generation Higgs yukawas

• using charm tagging for h→cc̄ inclusive

decays

• exclusive decays: h→Υγ (yb), 


h→J/ψγ (yc), h→φγ (ys)

• potentially isotopic shift measurements

44 Delaunay, Ozeri, Perez, Soreq, 1601.05087 Perez, Soreq, Stamou, Tobioka, 1503.00290 Kagan, Perez, Petriello, Soreq, Stoynev, JZ, 1406.1722 Bodwin, Petriello, Stoynev, Velasco, 1306.5770 Konig, Neubert, 1505.03870

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

300 fb-1 p r e l i m i n a r y

higgs flavor non- universality

• for up-quarks and charged leptons the

non-universality established

• how about down quarks?
• possible from pT and η distribution of h

45

yu=0 yu=yb

Soreq, Zhu, JZ, work in progress

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

talk by M. Pieri at LHCP2015

measurements

• J

P=0 + preferred (at 97.8% C.L. over 0

• )

46 ATLAS-CONF-2013-013; 
 CMS PAS-HIG-13-002

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

talk by M. Pieri at LHCP2015

measurements

• J

P=0 + preferred (at 97.8% C.L. over 0

• )

46 ATLAS-CONF-2013-013; 
 CMS PAS-HIG-13-002

CLFV, June 20 2016

• J. Zupan Prospecting for New Physics...

muon yukawa

• similarly, κ

̃ "≠0 induces muon EDM

• dominant contributions at 2-loop


• experimental bound


• compare with

47 thanks to J. Brod Muon (g-2) Collaboration, 0811.1207 " " " " " " " " " ν"

|˜ κµ| < 1.8 × 105

CMS-HIG-13-007; ATLAS 1406.7663

Br(h → µ+µ−) < 1.5 × 10−3

q |κµ|2 + |˜ κµ|2 < 7.0