The diphoton excess as a gravity mediator of Dark Matter Veronica - - PowerPoint PPT Presentation

The diphoton excess as a gravity mediator of Dark Matter

Veronica Sanz (Sussex) IC HEP seminar, May 2016

• Challenges for Run2
• The diphoton excess
• Models for the diphoton
• A spin-two candidate
• The excess and DM
• Conclusions

Outline

Challenges

Standard Model

• f Particle Physics

Predictive, successful paradigm being tested to higher and higher precision at the LHC Based on QFT, symmetries (global/gauge) and consistent ways to break them Foundation from which we develop theories beyond the SM

Challenges

• jfjf

Standard Model of Particle Physics

Light Higgs Matter/ Antimatter Dark Energy Dark Matter Quantum Gravity CP QCD

SYMMETRIES & DYNAMICS

Inflation Neutrinos Unification finding our path through

UNIFIED FRAMEWORK

aiming for a

Example of a unified framework: Supersymmetry

Unifies concept of bosons and fermions Candidates for Dark Matter Light scalar bosons Unification of strong/EM/weak forces Component of Quantum Gravity Matter/Antimatter asymmetry New mechanisms Inflation, Neutrinos and Dark Energy The discovery of SUSY at LHC first step to understand many aspects of Nature

’t Hooft, Veltman, Weinberg…

Run2 more lumi and energy foundation more precise, better ways of testing the Standard Model e.g. total rates to differential distributions

H+jets, VV distributions, shower models

e.g. top coupling to the Higgs

Run2 more lumi and energy foundation more precise, better ways of testing the Standard Model Enthusiasm and dedication of the community ground-breaking discovery challenges our understanding of Nature new particles, new principles

e.g. SUSY particles, hidden sector, QG effects, quasi-conformal strong dynamics…

This is not just wishful thinking we know the SM is not the ultimate theory

Dark Universe Neutrinos Baryogenesis

Evidence

Run2 has the potential to shed light on the origin

• f these observations

and on theoretical conundrums (e.g. naturalness)

DARK MATTER

THEORY

Discrete symmetries Dynamical stability self-interactions Link to Higgs…

DIRECT DETECTION COLLIDERS CMB: relic, tilt INDIRECT DETECTION SIMULATIONS

Unique opportunity Dark Matter

• The diphoton excess

What is it?

An excess in a channel with two photons at an invariant mass of about 750 GeV What we knew before Dec 2015 Run 1: CMS already a (less significant) excess, ATLAS did not show above 600 GeV

• Dec 2015

excess in both ATLAS and CMS Run2 data scalar, e.g. more Higgses tensor, e.g. spin-two graviton

Moriond 2016

• ATLAS and CMS results for s=0 & s=2

narrow and wide

• ATLAS analysis note public
• CMS update including improvements

in mass resolution and 0T data-set

Significance

• ex. interpreted as a gluon-fusion narrow scalar

(similar results for spin-two)

ATLAS 3.6

CMS 3.4 (remember LEE should be taken only once)

no Run1 combination

1603.06566

Production

Kick from 8 to 13 TeV from non-valence quarks or gluons sizeable cross section & narrow resonance indicates gluon-initiated

but other productions, incl diphoton still an option

Kinematics

where are the photons? EBEB vs EBEE

CMS

Initially (Dec), it looked as if kinematics were funny

0.5 1 1.5 2 2.5 3 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45

γ γ → SM pp s=0 s=2 BARREL ENDCAP

|ηγ|

dσ σdη

Han, Lee, Park, VS.

but s=0 and 2 are not so different

but we didn’t have ATLAS to compare with

but we didn’t have ATLAS to compare with

Kinematics

where are the photons? EBEB vs EBEE Initially (Dec), it looked as if kinematics were funny

CMS

post-Moriond Signal support in both ATLAS and CMS in the central region

Kinematics

Is this excess coming along other objects?

• 1. It doesn’t recoil (much)

Kinematics

Is this excess coming along other objects?

• 2. No electrons or muons

e.g. from ATLAS analysis

• “In addition, no electron or muon

candidates have been found, with > 10 GeV and < 2. (electrons) or 2.7 (muons) in the events with invariant masses between 700 GeV and 840 GeV.

pT

|η|

Kinematics

Is this excess coming along other objects?

• 3. No high-pT jets

jet anti-kT 0.4 pT> 25, eta< 4.4 disfavours bb, VBF and photon fusion

Kinematics

Is this excess coming along other objects?

• 4. No MET

Kinematics

Narrow or wide?

ATLAS

CMS

prefers narrow slight preference wide (0.3 sigma)

• verall

no preference for wide

Signal strength

compatibility? Run1 vs Run 2 and CMS vs ATLAS

Ellis et al. 1512.05327

theorists combination in Dec

ATLAS2 CMS2 CMS1

6.2 ± 1.0 (fb) (local)

Other final states

A heavy resonance in two photons? it couples to SM gauge interactions we expect WW, ZZ and Zgamma (and hh)

light Higgs into diphotons is not like the 750 GeV

Higgs below the threshold of WW, ZZ, suppressed BRs

Model-independent prediction: diphotons means there must be at least one non-zero BR(Z-gamma) and/or BR(ZZ)

gγγ = c1α1c2

W + c2α2s2 W

gzγ = (c1α1 − c2α2)s2W gzz = c1α1s2

W + c2α2c2 W

non-zero coupling to photons coupling to ZZ and/or Zphoton

No, VS, Setford. 1512.0

Spin

spin-0 vs spin-2 both compatible

• Models for the diphoton

Many papers written (~300 today) Some model-independent, most model-building

Spin

A new scalar J=0

Would this be the end of anthropics?

Spin

A new scalar J=0 Hooray SUSY!?

non-minimal

• r threshold effects

MSSM or NMSSM will not do compatibility with other searches, dof, perturbativity and tuning

Spin

A new scalar J=0 Hooray SUSY!?

non-minimal

• r threshold effects

MSSM or NMSSM will not do compatibility with other searches, dof, perturbativity and tuning

Composite dynamics?

glueball of new strong force

• r a pseudo-Goldstone boson

link to e.g. see-saw composite Higgs Dark Matter, Baryogenesis

No, VS, Setford.1512.05700

Spin

A kind of

J=2

1102.4299

Important hurdle is EWPTs

Spin

J=2

Experimental interpretations neglect this problem, theorists use AdS/CFT to find succesful models

recent progress

& in composite Higgs

1603.06980, 1603.08250 Dillon, VS. 1603.09550

Spin

A kind of aka

J=2

G × Gg

G/H → Φ

glueballs :

0++, 2++, . . .

Composite Higgs SM gauge

SM fermions

• VS. 1603.05574, 1507.03553

Mathieu, Kochelev and Vento 0810.4453

lattice pure-gauge

Spin

A kind of aka aka

J=2 lightest QBH 1->2 dominates

Dvali et al.

KK-graviton and

i.e. massive spin-2 resonance = smoking gun of extra-dimensions?

KK-graviton vs an

Guimaraes, Fok, Lewis VS. 1203.2917

G

ˆ G

i.e. massive spin-2 resonance = smoking gun of extra-dimensions?

KK-graviton glueball/QBH

KK-graviton vs an

Guimaraes, Fok, Lewis VS. 1203.2917

G

ˆ G

i.e. massive spin-2 resonance = smoking gun of extra-dimensions?

KK-graviton glueball/QBH

propagation

KK-graviton vs an

Guimaraes, Fok, Lewis VS. 1203.2917

G

ˆ G

i.e. massive spin-2 resonance = smoking gun of extra-dimensions?

KK-graviton

propagation

Pauli-Fierz Pauli-Fierz

glueball/QBH

KK-graviton vs an

Guimaraes, Fok, Lewis VS. 1203.2917

G

ˆ G

i.e. massive spin-2 resonance = smoking gun of extra-dimensions?

KK-graviton

propagation

Pauli-Fierz Pauli-Fierz

interactions

glueball/QBH

KK-graviton vs an

Guimaraes, Fok, Lewis VS. 1203.2917

G

ˆ G

i.e. massive spin-2 resonance = smoking gun of extra-dimensions?

KK-graviton

ci M GµνT µν

i,SM

propagation

Pauli-Fierz Pauli-Fierz

interactions

?

ci

M ∼ TeV

• verlap G with fields i and

glueball/QBH

KK-graviton vs an

Guimaraes, Fok, Lewis VS. 1203.2917

ˆ G couplings?

KK-graviton vs an

Guimaraes, Fok, Lewis VS. 1203.2917

ˆ G

Lorentz and gauge couplings? no dimension-4

KK-graviton vs an

Guimaraes, Fok, Lewis VS. 1203.2917

ˆ G

Lorentz and gauge couplings? dimension-5 same as in

Tµν

flavour and CP invariant no dimension-4

KK-graviton vs an

Guimaraes, Fok, Lewis VS. 1203.2917

ˆ G

Lorentz and gauge couplings? dimension-5 same as in

Tµν

flavour and CP invariant no dimension-4

KK-graviton vs an

Guimaraes, Fok, Lewis VS. 1203.2917

e.g. couplings to gauge bosons

ˆ G

Lorentz and gauge couplings? dimension-5 same as in

Tµν

ˆ G

G

couples like

same spin determination

How do we distinguish them? non-trivial question flavour and CP invariant no dimension-4

KK-graviton vs an

Guimaraes, Fok, Lewis VS. 1203.2917

The diphoton

From now on: calculations in

Composite Elementary

Aµ

global symmetry weakly gauged

hTdark Tvisi

M a t t e r

• b

r a n e D a r k

• b

r a n e

Dark Matter EWSB, Higgs Matter Gauge Gravity mediators

S M

• b

r a n e D a r k

• b

r a n e

Gauge Gravity mediators

different 4D theories holographic to different bulk configurations A B …

Production/decay of KK

• Invisible decay rates
• Production cross section for gg→G

Henceforth, c1 = c2 : no Zγ decay.

phase space suppressed

scalar, fermion, vector DM

Mono-jet bounds

10MeV 1MeV 100MeV 1GeV 10GeV 0.1MeV 100 200 300 400 1 0.5 0.1 0.2 0.3 0.4 0.6 0.7 0.8 0.9 10MeV 1MeV 100MeV 1GeV 10GeV 0.1MeV

mDM [GeV]

Γ(G→DM,DM) Γ(G→vis,vis) c3 S = 1 S = 1

2

S = 0

G → W + W − G → Z Z G → γ γ G → g g

diphoton signal rates imposed; Invisible decay rate is subdominant.

cX = 1 : gg

WW

γγ

ZZ

Vector DM is the largest.

Bounds on KK graviton

g g

G

g g

Invisible decay & mono-jet

LHC 8TeV γγ allowed LHC 13TeV γγ excess LHC 8TeV mono-jet allowed

LHC 8TeV γγ allowed

L H C 1 3 T e V γ γ e x c e s s 5fb 11fb

c3

c1

10−2 10−1 1 10−2 10−1 1 3 3

L H C 8 T e V m

• n
• j

e t a l l

• w

e d

f a v

• r

e d

Γ(G→DM,DM) = 0.1GeV

LHC 8TeV γγ allowed

L H C 1 3 T e V γ γ e x c e s s 5fb 11fb

c3

c1

10−2 10−1 1 10−2 10−1 1 3 3

LHC 8TeV mono-jet allowed

favored

LHC 8TeV γγ allowed LHC 13TeV γγ excess LHC 8TeV mono-jet allowed

ΓG = 45GeV

cgg × cγγ = 0.16 ⇣σpp→γγ 8 fb ⌘1/2⇣ Λ 3 TeV ⌘2⇣45 GeV ΓG ⌘1/2 .

KK graviton as DM mediator

DARK MATTER

THEORY

Discrete symmetries Dynamical stability self-interactions Link to Higgs…

DIRECT DETECTION COLLIDERS CMB: relic, tilt INDIRECT DETECTION SIMULATIONS

DARK MATTER

THEORY

Discrete symmetries Dynamical stability self-interactions Link to Higgs…

DIRECT DETECTION COLLIDERS CMB: relic, tilt INDIRECT DETECTION SIMULATIONS

DM annihilation

X X G

γ,g,WT,ZT

G G X X X

cX cX cX γ,g,WT,ZT (σv)t ∼ c4

Xm2 X

Λ4 ⇣mX mG ⌘8 ca

(σv)s ∼ vn c2

Xc2 am2 X

Λ4 ⇣mX mG ⌘4

[HML, M.Park,

• V. Sanz, 2013, 2014]

Scalar and fermion DM

• Invisible decay rates (given in unit of GeV) are small

in the region of correct relic density.

• Correct relic density is obtained near resonance,

due to velocity-suppressed annihilation.

Vector DM

• Invisible decay rate is larger than the cases with
• ther spins, but is still small.
• Correct relic density can be obtained even away

from resonance, due to s-wave annihilation.

DARK MATTER

THEORY

Discrete symmetries Dynamical stability self-interactions Link to Higgs…

DIRECT DETECTION COLLIDERS CMB: relic, tilt INDIRECT DETECTION SIMULATIONS

Direct detection

,

= 0.472 − 0.952(MILC).

LS−N = ξg S2GµνGµν, ξg = cScg 6Λ2 m2

S

m2

G

,

G DM DM

cS/Λ cg/Λ

g g

• Gluon coupling is unconstrained by direct detection.

DARK MATTER

THEORY

Discrete symmetries Dynamical stability self-interactions Link to Higgs…

DIRECT DETECTION COLLIDERS CMB: relic, tilt INDIRECT DETECTION SIMULATIONS

Indirect detection - lines

• Spectral gamma-ray line (Fermi-LAT, HESS, CTA, etc):

γγ, GG→ γγγγ channels (vector DM)

• BR of DM annihilation into a photon pair less

than 1% of thermal cross section for DM mass ~ a few 100GeV.

[Chu, Hambye, Scarna, Tytgat, 2012]

• Bounds from Anti-proton & Fermi dwarf galaxies

constrain thermal cross section for gg & WW.

• Continuum gamma-ray (Fermi-LAT dwarf galaxies):

WW, ZZ channels (scalar & vector DM)

• Anti-proton (PAMELA, AMS-02): gg channel (vector DM)

Indirect detection -

Indirect detection

500 1000 2000 0.05 0.10 0.50 1

relic abundance

Fermi

HESS

mG Λ

mDM (GeV)

mG = 750 (GeV)

Conclusions

• Two excesses at roughly 3.5sigma at 750 GeV

and cross section ~5 fb. Width and spin still

• TBD. Excess doesn’t come with high-pT
• bjects. Most compatible with gluon-fusion
• Models of spin-zero:

standard SUSY. standard AdS/CFT techniques required

• Spin-two would probe

graviton/Quantum Black Holes diphoton resonance common origin: correlations with DD/ID.

Whatever this is, making sense of naturalness, Dark Universe and model-building techniques is a challenge for theorists. 300 papers in ~ 4 months, we are up to it!