ams-02 antiprotons reloaded - taup · pdf fileams-02 antiprotons reloaded martin w. winkler in...

AMS-02 Antiprotons Reloaded

Martin W. Winklerin collaboration with R. Kappl and A. Reinert

based on JCAP 09/2014 and arXiv:1506.04145

TAUP 2015Torino

September 9 2015

Martin W. Winkler (Bonn University) AMS-02 Antiprotons September 9 2015 1 / 14

Why Antiprotons?

low fraction of antimatter in cosmic rays p̄/p ∼ 10−4

very sensitive probe for new physics

complemantary to gamma ray searches

1 101 10210-6

10-5

10-4

10-3

10-2

10-1

T @GeVD

Fp

@Hm2

ssr

Ge

VL-

1D

200GeVHiggsino

Background

example: dark matterpair-annihilation

no clear spectral featuresexpected

precise prediction for the p̄-background is indispensable


Secondary Antiprotons

scattering of primary cosmic rays (p,He) on the interstellar matter

qsec(T ) ∼∫

dT ′(dσdT

)p̄ prod

nAISMΦA A = H,He, . . .

1 101 102 103 104 105

103

104

T [GeV/n]

ΦiTOA·T

2.7[m

-2sr

-1s-1(GeV

/n)1.7] Proton

Helium

CREAM

AMS-02

primary proton andhelium fluxesYoon et al., Astrophys. J. 728 (2011)

Aguilar et al., Phy. Rev. Lett. 114 (2015)

clear indication ofspectral breaks


Antiproton Cross Sections

new calculation of p̄ productiondi Mauro et al., Phys. Rev. D90 (2014)

Kappl et al., JCAP 09 (2014)

experimental data from NA49NA49 collaboration, Eur. Phys. J. C65 (2010)

hyperon decay

ç ç ç ç çç

çç

çç

çç

çç

çç

çç

ç

0.00 0.05 0.10 0.15 0.20 0.25 0.3010-3

10-2

10-1

xf

dn

L�d

xf

0.2 ´ dn�dxf

0.3 ´ dn�dxf

data from Alt et al., Eur. Phys. J. C45 (2006)

isospin enhanced n̄ production

��

� �

�

�

�

�

��

è

èè

è

è

è

è

è

è

è

èè è- 0.1 0.0 0.1 0.2 0.3

0.05

0.10

0.15

0.20

xf

dn

�dx f

isospin factor 1.37isospin factor 1

�� p n Dataèè p p Data

data from Fischer et al., Heavy Ion Phys. 17 (2003)

improved modeling ofproton-nucleus scattering


Propagation

propagation: random walk through the galaxy

from D. Maurin

diffusion equation

∇(−K ∇Np̄ + Vc Np̄) + ∂E (bloss Np̄ − KEE ∂ENp̄) + Γann Np̄ = qp̄

semi-analytic solution in two-zone diffusion modelMaurin et al., Astrophys. J. 555 (2001), Donato et al., Astrophys. J. 563 (2001)

five transport parameters: K0, δ, L, Vc , Va ⇐= B/C analysis


Antiproton Excess in AMS-02?

preliminary data on the antiproton fraction in cosmic raysA. Kounine, Talk at the AMS Days at CERN (2015)

dark matter interpretationIbe et al., Phys. Rev. D91 (2015), Hamaguchi et al., Phys. Lett. B747 (2015)

background underestimated? Giesen et al., arXiv:1504.04276 (2015)


A Glance at B/C

preliminary B/C dataA. Oliva, Talk at the AMS Days at CERN (2015)

101 102 103

10-1

ℛ [��]

�/�

��

�� /�

��-�� /�

indicate that propagation parameters are outdated ⇐= reanalysis


Primary Fluxes

10-1 1 101 102 10310-13

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

1

101

102

T [GeV/n]

ΦiTOA·T

2.7

[m-2sr

-1s-1(GeV

/n)1.7]

Carbon

Oxygen·10-2

Nitrogen·10-4

Neon·10-6

Magnesium·10-8

Silicon·10-10

CREAM-II

HEAO

PAMELA

ACE

B/C ratio used to determinepropagation parameters

B is pure secondary

C, N, O, Ne, Mg, Sispallation contributes& 98% to B flux

data from ACE, HEAO,CREAM-II, PAMELALave et al., Astrophys. J. 770 (2013), Engelmannet al., Astronom. Astrophys. 233 (1990), Ahn etal., Astrophys. J. 707 (2009), Adriani et al.,Astrophys. J. 791 (2014)


Spallation Cross Sections

σspall: straight-ahead approximation

constant at T & 10 GeV

10-1 1 101

30

35

40

45

50

� [��]

σ(��

→�)[��]

��

��

��

Webber parameterizationAstrophys. J. Suppl. 144 (2003)

large uncertainties, nohigh-energy data

introduce energy biasMaurin et al., Astron. Astrophys. 516 (2010)

needed: experimental data on spallation cross sections


B/C Analysis

new AMS-02 data on B/C ratioA. Oliva, Talk at the AMS Days at CERN (2015)

selected 500 configurations, trend towards smaller δ = 0.3− 0.6


B/C Analysis

new AMS-02 data on B/C ratioA. Oliva, Talk at the AMS Days at CERN (2015)

0 5 10 15 200.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Vc @ kpc Myr-1D

∆

MED

selected 500 configurations, trend towards smaller δ = 0.3− 0.6


Antiproton Fraction

comparison of p̄ background with new AMS-02 dataA. Kounine, Talk at the AMS Days at CERN (2015)

1 101 102

10-5

10-4

� [��/�]

�/�

��

��

�/� ��

��-�� /� ��

updated background consistent with data


Antiproton Fraction


1 101 102

10-5

10-4

� [��/�]

�/�

��

��

� /� ��

��-�� /� ��



Antiproton Fraction


1 101 102

10-5

10-4

� [��/�]

�/�

��

��

��

��-�� /� ��



Comparison of p̄/p and B/C

101 102 103

10-1

ℛ [��]

�/�

( � /� )× ��



101 102 103

10-1

ℛ [��]

ℛ-��

ℛ -��/�

( �/� )× ��

p̄/p flatter by ∼ R0.25



101 102 103

10-1

ℛ [��]

ℛ-��

ℛ -��/�

( �/� )× ��

p̄/p flatter by ∼ R0.25

explained by injection

10 50 100 500

1000

2000

3000

4000

� [��/�]

��/Φ

�

��_/Φ

�

�-��


Remark on Propagation Unceratinties

10-1 1 101

30

35

40

45

50

� [��]

σ(��

→�)[��]

��

��

��


Conclusion

substantial progress in modeling antiproton production

AMS-02 B/C data have strong impact on propagation parameters:higher slope of diffusion coefficient

AMS-02 antiproton data are consistent with background


ams-02 antiprotons reloaded - taup · pdf fileams-02 antiprotons reloaded martin w. winkler in...

Documents