Searching for flavored new physics at the LHC

Searching for flavored new physics at the LHC

J. Martin Camalich

GenT Workshop

December 18 2019

Why studying Flavor Physics in the 2020’s? 1 - Big Questions

CKM and mass matrices: Parametrizations of flavor phenomena in the SM

The SM Flavor Puzzle

I

Specific values of quark masses seem “tuned”

Anthropic arguments!

I

Origin of CP-violation, baryogenesis, strong CP

I

Why does Nature need three generations at all?

However, the solution might not be accessible at the energies at reach. . .

2 - Strong physics programme for the decade

Jure Zupan, arXiv: 1903.05062

I

Current

Projection HL-LHC only

“Opportunities in Flavour Physics at the HL-LHC and HE-LHC”, A. Cerriet al., CERN Yellow Rep.Monogr. 7 (2019) 867-1158

Belle II is just ramping up luminosity!

J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 3 / 22

Very sensitive probes of “generic” new physics

Theorem: FCNC are “Loop-Suppressed” in the SM!

I

Prototypical example: FCNCs

M

∼

Weak

z}|{ G

z }| { y

16π

Flavor

z }| { (V

V

)

| {z }

GIM

I

Flavour observables probe (indirectly) very high energy scales!

M. Neubert at EPS 2011

3 - Flavor anomalies!

Lepton-universality violation in B decays?

“The flavour of new physics”, JMC & J. Zupan, CERN courier, May/June 2019

“R

anomaly” in B → D

`ν!

I

Excesses observed at ∼ 3σ

I

Other “anomalies” in b → (u, c)`ν

I

Λ

∼ 3 TeV Talk by Clara Murgui

“R

anomaly” in B → K `` (FCNC)!

I

Other anomalies in b → sµµ

F

Branching fractions

F

Angular analysis B → K

µµ

I

Up to 4-6σ in global fits

I

Λ

∼ 30 TeV Talk by Marco Fedele

J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 5 / 22

Flavor physics was instrumental in discovering and shaping the SM

I

Nuclear β-decays: Discovery weak interactions and neutrino

I

Rare Kaon-decays: Discovery of the charm quark

I

Kaon decays: Discovery of CP violation = ⇒ Discovery of 3 generations

Expect the unexpected

Thanks to Zoltan Ligeti for sharing this

Status of LFUV in b → cτ ν decays

R

=

B( ¯B→D^(∗)`⁻ν)¯

where ` = e, µ

Babar, Belle and LHCb are independently in tension with SM!

G. Caria @ Moriond EW 2019 (arXiv:1904.0879)

I

NEW: Belle with semi-leptonic tag

F

Consistent at ∼ 1σ with SM!!

I

World average now at ∼ 3σ from SM. . .

Why studying the R D

anomalies?

Λ

∼ 3 TeV

If true, find the “ultimate” collider search

J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 7 / 22

EFT of new-physics in b → cτ ν

Low-Energy EFT Lagrangian

L_eff⊃−^{GF Vcb}√

2 [(1+`</sup><sub>L</sub>)`γ¯µ(1−γ5)ν`</sub>·¯cγ<sup>µ</sup>(1−γ<sub>5</sub>)b+<sup>`R`γ¯<sub>µ</sub>(1−γ<sub>5</sub>)ν<sub>`¯cγµ(1+γ5)b +`

SL`(1−γ¯ <sub>5</sub>)ν<sub>`</sub>·¯c(1−γ₅)b+^`

SR`(1−γ¯ <sub>5</sub>)ν<sub>`</sub>·¯c(1+γ₅)b+<sup>`</sup><sub>T</sub>`σ¯_µν(1−γ₅)ν_`·¯cσ^µν(1−γ₅)b]+h.c.

,

I

The SM + 5 New-Physics operators

Matching to high-energy Lagrangian – SMEFT

I

Symmetry relations for

In charged-currents

:

O

= i Λ

H ˜

D

H

u ¯

γ

d

RHC is lepton universal:

≡

+ O(

Λ4 NP

) ⇒ Cannot explain LFUV in R

!

EFT of new-physics in b → cτ ν

Low-Energy EFT Lagrangian

L_eff⊃−^{GF Vcb}√

2 [(1+`</sup><sub>L</sub>)`γ¯µ(1−γ5)ν`</sub>·¯cγ<sup>µ</sup>(1−γ<sub>5</sub>)b+<sup>`R`γ¯<sub>µ</sub>(1−γ<sub>5</sub>)ν<sub>`¯cγµ(1+γ5)b +`

SL`(1−γ¯ <sub>5</sub>)ν<sub>`</sub>·¯c(1−γ₅)b+^`

SR`(1−γ¯ <sub>5</sub>)ν<sub>`</sub>·¯c(1+γ₅)b+<sup>`</sup><sub>T</sub>`σ¯_µν(1−γ₅)ν_`·¯cσ^µν(1−γ₅)b]+h.c.

,

I

The SM + 5 New-Physics operators

Introducing light right-handed neutrinos N

5 extra New-Physics operators

I

They do not interfere with the SM!

L_eff⊃−^{GF Vcb}√

2 ˜<sup>`</sup><sub>R</sub> `γ¯µN_R¯cγ^µ(1+γ₅)b

Consider 5 operators to explain R

:

, ˜

,

,

,

J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 8 / 22

Trajectories of EFT scenarios: pre- and post-Moriond ’19

SM

Tensor Current

Scalar- Tensor

Rui-xiang Shi, Li-sheng Geng, B. Grinstein, S. Jäger & JMC, JHEP 1912 (2019) 065

Best scenario also enters through NEW current-current interactions

Evolution of the NP scenarios from pre- to post-Moriond 2019

Pre-Moriond Post-Moriond Best fit Pull

Best fit Pull

0.11(3) 4.25 0.07(2) 3.43

˜

0.48(6) 4.25 0.39(5) 3.43

0.37(1) 4.16 −0.03(1) 3.30

See also talk by Clara Murgui

1

“Current-current” scenarios still perform best Λ

' 3.7 TeV = ⇒ Λ

' 4.6 TeV

2

“Tensor” scenario is now driven by interference piece

Br(Bc→ τν)>30%

Br(B^c

→τν)>10%

-1.0 -0.5 0.0 0.5 -0.5

0.0 0.5 1.0

ϵ

ϵ

3

“Scalar” scenarios still limited by B

→ τ ν

F

Crossing-symmetry in decay

Alonso, Grinstein & JMC,PRL118, 081802, Akeroyd & Chen PRD96, 075011 J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 10 / 22

Crossing-symmetry connection to the mono-tau signature at the LHC

Greljo, JMC & Ruiz-Álvarez, PRL122, 131803

I

The proton is flavored. . .

Cross-section at s m

σ

σ

∼ P

i

L

⊗ |V

|

α

|

|

L

⊗ |V

|

I

NP suppressed by CKM and PDF’s

I

NP enhanced by s

/M

I

NP sensitivity is quadratic

Search excess in tails of pp → τ + MET!

Crossing-symmetry connection to the mono-tau signature at the LHC

Greljo, JMC & Ruiz-Álvarez, PRL122, 131803

I

The proton is flavored. . .

I

Cross-section at s m

J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 11 / 22

A comment on the LHC bounds on effective operators

History: First discussed related to nuclear β decays (4-fermion)

I

Competitive on scalar/tensor scenarios

Cirigliano, González-Alonso, Graesser JHEP1302(2013)046

LHC bouds on light-quarks can have consequences on R

!

I

∼ 2σ excess on W → τ ν at LEP

δg

− δg

= 0.0134(74)

Ciriglianoet al.PRL122 (2019) no.22, 221801

LHC data and simulations of pp → τ h X + MET

W

searches available from run 2 (13 TeV)

I

ATLAS: 36.1 fb

I

CMS: 35.9 fb

Collider Simulation: MadGraph5@NLO I Pythia8 I Delphes 3

I

LO with 6 2j at parton level

I

Kinematic cuts/Delphes configuration as reported/recommended by collaborations

I

Agreement with official simulations . 20%

1000 1500 2000 2500 3000

) [GeV]

miss ,pT τ T( m

−2 10

−1 10 1 10 102

Events ATLAS W+jets estimation

W+jets EFT Tensor coupling W', m=2 TeV, 22% width

Greljo, JMC & Ruiz-Álvarez, PRL122, 131803, Supp. Material J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 13 / 22

LHC bounds on EFT operators

★

★

★

★

★

★

★

★

◆

◆

◆







●

●

●

○

○

○

0.0 0.2 0.4 0.6 0.8 1.0 1.2

∞ 4 3 2 1

| ϵ Γ |

Λ [ TeV ]

★R_D(*) ◆ATLAS CMS ●LHC ○HL-LHC(2σ)

ϵ

ϵ ˜

Vector

Tensor

Scalar - Tensor

Greljo, JMC & Ruiz-Álvarez, PRL122, 131803 (updated)

LHC is sensitive to NP scenarios addressing anomalies!

“No-loose theorem” for the discovery of NP at the LHC

Caveats of the EFT analysis

Cross-section in EFT diverges at s → ∞

I

EFT stops being valid for √ s ' Λ

I

Λ ∼ 1-10 TeV for R

∼ Partonic √

s at the LHC Sensitivity per bin of tau’s transverse mass

△ △

△

△

△

△

△

△ △

△

△

△

△

△

△

○ ○ △

○

○

○

○

○ ○ ○

○

○ ○

○

○

○

○

□ □ □ □ □ □

□ □

□

□

□

□

□

□

□

△ATLAS 36.1 fb^-1

○ATLAS 3 ab^-1

□ATLAS 3 ab^-1(noNrescaling)

500 1000 1500 2000 2500 3000

1.00 1.01 1.02 1.03 1.04 1.05

MT[GeV]

σJack σT

I

For projections assume systematics scale as 1/ √

L

Low M

limited by SM W → τ ν

background

F

High M

limited by statistics

Most sensitive bins . 2 TeV!

Beyond one needs explicit mediators and UV completions of the EFT

J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 15 / 22

Simplified mediators for the R D

anomaly

1

Uncolored mediators

¯ c, ¯ b

W

, H

b, c ¯ ν, τ

τ

, ν

I

Jacobian bump search

2

Colored mediators

¯ c, ¯ b

LQ b, c

¯ ν, τ

τ

, ν

I

Excess in tails

Mediator SU(3) SU(2) U(1) Current Scalar Tensor

W

1 3, 1 0, +1 X X X

H 1 2 +1/2 X X X

S

3 1 -1/3 X X X

R

3 2 +7/6 X X X

U

3 1 +2/3 X X X

We do not consider charged Higsses because of B

→ τ ν

A total of 8 different solutions!

Leptoquark solutions

A total of six leptoquark solutions

I

S

and U

produce both LH and RH solutions

I

S

and R

produce scalar and tensor solutions

F

One S

scalar-tensor solution:

= −

SL

/4

F

One R

(complex) scalar-tensor solution:

= +

SL

/4

One S

-R

“pure” tensor solution

⁠U⁠1⁠⁠L⁠e⁠p⁠t⁠o⁠q⁠u⁠a⁠r⁠k⁠⁠⁠

⁠

L⁠H⁠C ⁠e⁠x⁠c⁠l⁠u⁠s⁠i⁠o⁠n⁠⁠⁠@⁠⁠⁠2⁠σ

RH

LH

Greljo, JMC & Ruiz-Álvarez, PRL122, 131803 (updated) I

All scenarios converge to EFT results for m

& 2 TeV

J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 17 / 22

The complex R 2 -leptoquark solution

A (complex) scalar-tensor solution with

= +

L

/4

Becirevicet al.arXiv: 1806.05689

This model should be discovered/ruled-out at HL-LHC

W 0 solutions

W

in the SU(2)-triplet severely constrained by B

mixing and pp → τ

τ

I

Focus on the W

Famous AG plot for W

in pp → τ

+ MET!

5

W

solutions pushed to nonperturbative or light!

J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 19 / 22

The LHC flavor-physics program: b → uτ ν

Take b → uτ

ν ¯ decays: Naturally linked to R

anomalies

I

Rare processes: Γ ∼ |V

|

I

Tricky final states: τ

, but also π, ρ, p¯ p . . .

B(B⁻→τ⁻ν)=1.09(24)×10¯ ⁻⁴ (PDG), B(B⁰→π⁻τ⁺ν)<2.5×10¯ ⁻⁴ (Belle)

I

Current operators

Scalar and tensor operators

Data set Scalar Tensor

B

→ π

τ

ν ¯ [-1.75, 0.94] [-1.25, 0.57]

LHC 1.23 0.34

HL-LHC 0.37 0.10

The LHC can compete with

classic low-energy flavor probes!

The LHC flavor-physics program: Charm physics

Fuentes-Martin, Greljo, JMC, Ruiz-Álvarez 2000.xxxxx

Example: Tauonic charm transitions

Little phase space

m

− m

' 90 MeV vs.

Charged-current decays: Only D

→ τ

ν (CLEO & BESIII)

BR(D⁺→τ⁺ν_τ)=τ_D+^mD+m τ2f2

D+G2 F|Vcd|2β4

τ 8π

1−_A+ ^m 2 D mτ(mc+mu)_P

2

I

Semi-leptonic D

→ K ¯

(π

)τ

ν decays forbidden by phase space!

Neutral current decays: D

→ τ

τ

, D

→ τ

µ

forbidden by phase space!

Only search of NP will be from LHC!

J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 21 / 22

The LHC flavor-physics program: Charm physics

Fuentes-Martin, Greljo, JMC, Ruiz-Álvarez 2000.xxxxx

Example: Tauonic charm transitions

Little phase space

m

− m

' 90 MeV vs.

Complementarity in the charged currents

c → sτ

ν c¯ s → τ

ν c → dτ

ν c d ¯ → τ

ν

−

0.009 0.015

[−0.066, 0.007] [−0.24, 0.16]

−

0.018 0.030

[−0.004, 0.040] [−0.10, 0.15]

− 0.004 − 0.0061

Comments & caveats

1

Complementarity in axial currents: Access δg

vertex corrections (light leptons!)

2

Model-dependence of collider bounds: Λ

' 2.5 TeV

Conclusions

1

“R

anomalies”: pp → τ

X + MET currently sensitive to NP models

I

RHC solutions with W

or LQ in tension with data

2

“No-loose theorem”: HL-LHC has the potential to discover “the model”. . . . . . whatever it might be ...

I

Bottom-up: EFT I Simplified mediators

I

Flavor: Direct correlation between R

and LHC

I

Conservative: Extra flavor/Lorentz components increase excess

Baker, Fuentes-Martín, Isidori, König, arXiv: 1901.10480

I

Additional ideas could enhance sensitivity!

3

“LHC Flavor physics program”: Provide specific inputs to flavor physics

I

Promising with tau-leptons

I

Very promising in charm physics!

J. Martin Camalich (IAC & ULL) Searching for flavored new physics at the LHC December 18 2019 22 / 22