Cosmic Ray Anomalies from the MSSM?

Randy Cotta (Stanford/SLAC)

In collaboration with: J.A. Conley (Bonn) J.S. Gainer (ANL/NU) J.L. Hewett (SLAC) T.G. Rizzo (SLAC)

Based on: 0812.0980 0903.4409

1007.5520

Anomalous Cosmic Ray Data?

• Measurements deviate from expected curves

• Excess CR antimatter could be a signal of DM annihilation…

“The” Astrophysical Theory Curve

Posi

tron

Fra

ctio

n: e

+ /

(e- +

e+ )

p

/ p

PAMELA 0810.4994

PAMELA 0810.4995

E3 *

(e- +

e+ )

(G

eV2 m

-2 s-1

sr-1

)

FERMI-LAT 0905.0025

astrophysics

? ? ?

? ? ?

? ? ? ? ? ? ? ? ? ? ? ? ? particle Halo

Also: Discovering DM Indirectly

is very hard. LOTS of uncertainty unrelated to the particle model:

i) Need: <σv> ≥ 10-23cm3s-1, MSSM: <σv> ~ 10-26cm3s-1 => Boost: B*<σv>

ii) Need: DM

DM

(lepton)-

(lepton)+

DM

DM

quark

quark

Studied MSSM models not especially

“leptophilic.”

BUT: MSSM== mSUGRA !! But:

mSUGRA: see e.g. Barger etal. (0806.1962)

Are We Seeing MSSM WIMPs? The Lore: No.

MLSP

# M

odel

s

M_χi (GeV)

Ωh2|LSP

# M

odel

s

Ωh2|LSP >= 0.1 (Ωh2|LSP ~ Ωh2|WMAP )

SUSY Without Prejudice C.F. Berger, J.S. Gainer, J.L. Hewett, T.G. Rizzo (Re. Also: My Phuong Le’s Talk) 0812.0980

LSP Mass (GeV)

<σv>

(10-2

6 cm

3 s-1

)

LSP Mass (GeV) <σv>

*(ρ2

/ρo2 )

(10

-26 c

m3 s

-1)

General Models

Ωh2|LSP > 0.1 Models Thermal Rescaling:

ρ2=ρo2*(Ωh2|LSP /Ωh2

WMAP)2

ρo ~ 0.3GeV/cm3

Diverse Annihilation Phenomenology …

<σv>

*(ρ2

/ρo2 )

*BR

i (cm

3 s-1

)

General Models

Ωh2|LSP>0.1 Models

Annihilation Channel

~1.4M Annihilation cross sections from DarkSUSY

Diverse Annihilation Phenomenology …

<σv>

*(ρ2

/ρo2 )

*BR

i (cm

3 s-1

)

General Models

Ωh2|LSP>0.1 Models

Annihilation Channel

~1.4M Annihilation cross sections from DarkSUSY

pMSSM Model #11417

<σv>

τ+τ-

/<σ

v>bb

bar

<σv>τ+τ-*(ρ2/ρo2) cm3s-1

General Models

Ωh2|LSP>0.1 Models

Leptophilia?

80%/20%

Studies often take:

Br(χχ --> bb) ~ 80%

Br(χχ --> τ+τ-) ~ 20%

Diverse Annihilation Phenomenology …

E3 *

(e- +

e+ )

(G

eV2 m

-2 s-1

sr-1

)

Grasso et al. (FERMI) (0905.0636)

!!!

!!!

Posi

tron

Fra

ctio

n: e

+ /

(e- +

e+ )

Grasso et al. (FERMI) (0905.0636)

Dealing with “The” Astrophysical Background

Astrophysical background models have been VERY

uncertain until VERY recently.

With anomalies in the data we want to make sure we’re

not tuning background models to fit BG+Signal !!

Designing Astro-Models…

First…

…Last

Par. Type Par. Names Constrained By Also Note…

Proton Source Nn, γn Proton Abs. Flux (AMS01,ATIC,BESS, CAPRICE)

These are fixed at the beginning and never floated thereafter

Diffusion zh, D0xx, δ, VA, Vc B/C (HEAO-3, ATIC, CREAM)

zh and D0xx are “degenerate,” we scan zh. Radio clocks: zh>~2Kpc. δ expected in ~ 0.3-0.8. Here δ=0.33

Electron Source Ne, γe e+/(e++e-), (e++e-)

B-Field NB e+/(e++e-), (e++e-) Diffuse γ’s

NB~ few µG

ISRF (uFIR+uoptical), uoptical/uFIR

e+/(e++e-), (e++e-) Diffuse γ’s

(uFIR,uoptical) ~ default, Scan similar to Blandford etal. (0908.1094)

GALPROP/DarkSUSY, Scan+Constraints just like pMSSM, but NOT without prejudice, we look for pars. that are better for SUSY.

e+/(e++e-), (e++e-), pbar/p, fit above 10GeV

Our Astro-Background Scan… (NO SUSY added)

ASTRO-ONLY

Energy (GeV)

E3 *

(e- +

e+ )

(G

eV2 m

-2 s-1

sr-1

)

ASTRO-ONLY

Energy (MeV)

ASTRO-ONLY E2 *

(Flu

x) (M

eV m

-2 sr

-1 s-1

)

Diffuse Midlat. Gammas (10o<|b|<20o, 0o<b<360o )

Ant

ipro

ton/

Prot

on F

lux

Rat

io

Bor

on/C

arbo

n C

R F

lux

Rat

io

Energy (GeV)

Our Models (qty. 524)

Benchmark “Model 1” Grasso et al. (FERMI,

0905.0636)

Our Astro-Background Scan… (NO SUSY added)

ASTRO-ONLY

Energy (GeV)

E3 *

(e- +

e+ )

(G

eV2 m

-2 s-1

sr-1

)

ASTRO-ONLY

Energy (MeV)

ASTRO-ONLY E2 *

(Flu

x) (M

eV m

-2 sr

-1 s-1

)

Diffuse Midlat. Gammas (10o<|b|<20o, 0o<b<360o )

Ant

ipro

ton/

Prot

on F

lux

Rat

io

Bor

on/C

arbo

n C

R F

lux

Rat

io

Energy (GeV)

Our Models (qty. 524)

Benchmark “Model 1” Grasso et al. (FERMI,

0905.0636)

Energy (GeV)

Energy (GeV)

Posi

tron

Fra

ctio

n: e

+ /

(e- +

e+ )

ASTRO-ONLY

Our Models (qty. 524)

Benchmark “Model 1” Grasso et al. (FERMI,

0905.0636)

Global Fit χ2/dof (dof=36)

χ2(p

osi.

frac

.) / χ2

(tot.)

ASTRO-ONLY fits ASTRO+SUSY fits Global Fit (Astro)X(SUSY)

Global Fit χ2/dof (dof=36)

Bes

t Fit

Boo

st F

acto

r

B<500, χ2/dof <2.0

Benchmark “Model 1” and Our SUSY Model Set

All Astro Models and all SUSY Models

The SUSY-Added fits do significantly better than the ASTRO-ONLY fits.

Most cases: a significantly better fit to the PAMELA positron

fraction data

BEST FITS: χ2/dof = 1.54

With boosts in: B ~ 70-150

<σv>

τ+τ-

/<σ

v>bb

bar

<σv>τ+τ-*(ρ2/ρo2)cm3s-1

TEN Best SUSY Models

1)  annihilate dominantly to τ+τ-

2)  Most important to have a light stau.

3)  (Ωh2|LSP ~ Ωh2|WMAP ), some co-annihilation

4)  LSP is a (mostly bino) bino-higgsino admixture

5)  Rest of spectrum => Leptophilic.

Best-Fit CR Spectra for My Favorite SUSY Model …

B=156

e+/(e++e-)

pbar/p

(e++e-)

Diffuse Midlat. Gammas (10o<|b|<20o, 0o<b<360o )

E2 *

(Flu

x) (M

eV m

-2 sr

-1 s-1

)

B=156

B=156

B=156

Best-Fit CR Spectra for My Favorite SUSY Model …

B=156

e+/(e++e-)

pbar/p

(e++e-)

Diffuse Midlat. Gammas (10o<|b|<20o, 0o<b<360o )

E2 *

(Flu

x) (M

eV m

-2 sr

-1 s-1

)

B=156

B=156

B=156

For Much More: 1007.5520

Backup Slides…

So how do we choose δ …

Many more e- than e+

Background Positron Fraction: e+/(e++e-) ~ e+/e- ~ 2ary/1ary ~ E γe – γn - δ

Signal Positrons (SUSY): e+

SUSY ~ E - γs - δ

Small δ is desirable for SUSY visibility in e+/(e++e-) with lower Boosts.

We use δ=0.33

δ=0.33 δ=0.40 δ=0.50

diffusion convection

reacceleration energy losses

fragm. decay

e+/- are not as simple as stable nuclei but 1D result gives rough idea:

Is δ=0.33 OK?

CR e+/- and CR nuclei probe different regions of the galaxy

E>10GeV e+/- are cooled very efficiently by synchrotron, IC and brem. => e+/- come from the local ~ kpc.

Nucleonic CRs radiate negligibly => diffuse substantially throughout the galaxy.

B/C probes the average condition of a large portion of the galaxy.

Very tricky to associate the “δ” describing B/C with the “δ” that should be used to propagate local CR e+/-

Delahaye etal,1002.1910

~ 0.5Kpc

Irvine, CA.

Dist to Origin (kpc)

Frac

tion

of L

ocal

Sig

nal

SUSY ONLY Signals…

Green’s functions appropriate to each custom

astro-model are used to compute the SUSY signals

(i.e. GALPROP -> DarkSUSY )

Shown: positron and antiproton fluxes from a single SUSY model

for each astro-model used

Our Model Propagation

Energy (GeV)

E2 *

(Pos

itron

Flu

x) (G

eV m

-2 sr

-1 s-1

)

E*(

Pbar

Flu

x) (m

-2sr

-1s-1

)

Energy (GeV)

“Model 1” (0905.0636) Propagation

We Have More Ways to Fit the Data…

Scanning over loss parameters widens the basin of fit that one would get by tuning γe alone…

⇒ A wider variety of astrophysical backgrounds to which we’ll add our signal

⇒ A wider variety of green’s functions with which we’ll propagate our signal.

On to the Results…

Astro AND SUSY, Gammas… Diffuse Midlat. Gammas (10o<|b|<20o, 0o<b<360o )

E2 *

(Flu

x)

(MeV

m-2

sr-1

s-1)

B=156

•  Components from IC, π0-decay, Brem., point sources… uncertainties in the normalization of each component.

•  Did not use this quantity in the global fit b/c Astro-BGs bad fit to all data sets, new GALPROP default model will fit the FERMI data together, but all models built on the assumption of NO SUSY SIGNAL, all ordinary astrophysics.

Assuming the SAME B applies diffuse mid-latitude γs

SUSY Contribution to diffuse mid-lat. γs:

Some tension with FERMI preliminary data

But…

Astro AND SUSY, Gammas…

Assuming the SAME B applies to dwarf galaxies…

Dwarfs: boosted signals near LAT detection, pure τ models

are hardest to see.

Essig etal. 1007.4199

Dwarfs may be the fastest way to obtain believable evidence

for these scenarios!

OLD

NEW

Direct Detection?

Ten best pMSSM models span a sizeable range of DD cross

sections.

Cross sections highlighted here DO NOT include Boosts. Appropriate boost factor

depends on the considered origin of the boost

Awaiting More Data…

•  AMS-02 can measure CR antimatter better than any previous experiment.

•  AMS-02: size, duration and combination of sub-detectors => high acceptance with proton mis-ID @ e+/p+ ~ 10-6

-

Expected Performance (Superconducting)

http://www.er.doe.gov/hep/files/pdfs/HEPAP_AMS.pdf

Charge-Sign Dependent Solar Modulation…

G. Tarle, UCLA DM 2010 Conf., paper to appear

Sign-INdependent solar modulation factors out of the positron fraction.

Our strategy: avoid data below 10 GeV!!

Clem etal. ApJ 464 (1996)

3BFSs…

Bell, etal. 1009.2584

Calculated in a toy model that does a pretty good job reflecting the MSSM result…

Channels w/ extra W/Z compete with direct channels as the extra vector lifts the helicity suppression… Very interesting!

But… For our models annihilation to taus will always dominate over annihilation to electrons.

The numerator is universal: f(MW/Mχ), denominator is not: ~ (Mf /Mχ)2