Possible new physics of dark matter from recent cosmic ray measurements

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Possible new physics of dark matter from recent
cosmic ray measurements

• Bi Xiao-Jun
• IHEP, CAS
• 2009-10-1

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Standard cosmology
Dark matter (dark energy) exists in the universe.
However, we have to figure out its property.
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Nature of dark matter non-baryonic cold dark
matter

• Not in compact form, such as black holes,
  neutron stars? (MACHO -MAssive Compact Halo
  Objects)

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Non-baryonic

• From BBN and CMB, it has ?Bh20.02-0.002.
  Therefore, most dark matter should be
  non-baryonic. ?DMh20.113-0.009

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New physics beyond the SM

• Non-baryonic cold dark matter dominates the
  matter contents of the Universe. New particles
  beyond the standard model are required!
• New physics!

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Ideas of DM particles from theoretical particle
physics

• From QCD
• Axions
• From Grand Unified Theories String Theories
• Lightest supersymmetric particles
• From String Theories Extra-dimensions
• Kaluza-Klein Particles
• Others

SM has too many free parameters has the
hierarchy problem which makes it a low energy
effective theory. Almost all the extension of SM
predict new stable particles, which can be the
dark matter. Therefore, from the point of view of
particle physics, it is more nature to have dark
matter than no dark matter! (SM should not be the
final theory of everything.)
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Thermal history of the WIMP (thermal production)
Thermal equilibrium abundance
At T gtgt m, At T lt m, At T m/22,
,decoupled, relic density is inversely
proportional to the interaction strength
For the weak scale interaction and mass scale
(non-relativistic dark matter particles)
, if
and

WIMP is a natural dark matter candidate giving
correct relic density (proposed trying to solve
hierarchy problem).
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Detection of WIMP

• Indirect detection DM increases in Galaxies,
  annihilation restarts(??2) ID looks for the
  annihilation products of WIMPs, such as the
  neutrinos, gamma rays, positrons at the
  ground/space-based experiments
• Direct detection of WIMP at terrestrial detectors
  via scattering of WIMP of the detector material.

indirect detection
Direct detection
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Results of PAMELA, ATIC, Fermi and HESS
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PAMELA results Nature 458, 607 (2009) (citation
300Observation of an anomalous positron
abundance in the cosmic radiation
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ATIC bump at the electron/positron spectrum
Chang et al. Nature456, 362 2008
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Fermi results

• Fermi gives softer spectrum of (ee-) than ATIC.
  Excess exists above the conventional model

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HESS result

• HESS measures the Cherenkov light of the showers
  developed by high energy cosmic rays in the
  atmosphere.
• It can discriminate hardronic and EM showers.
  However, can not discriminate electrons and
  gammas.
• Electron flux is larger than gamma beyond the
  galactic plane.
• Energy resolution is at best 15.

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Summary of data

• PAMELA observed substantive positron excess
  beyond the standard prediction by cosmic ray
  physics above 10 GeV up to 80 GeV, which is
  consistent with previous results from HEAT and
  AMS01.
• Both ATIC and Fermi observed excesses at the
  electronpositron spectrum however, they are not
  consistent with each other
• ATIC data show very sharp falling at the
  electron spectrum at 600 GeV. It is consistent
  with the spectrum produced by dark matter Fermi
  shows softer spectrum which may be due to
  astrophysical sources
• No antiproton excess. The sources seem have to be
  leptonic.
• Assuming the conventional background from cosmic
  rays, in addition primary sources that generate
  equal amount of electron/positron, ATIC and Fermi
  are consistent with PAMELA separately, that each
  set of data can be explained by the same
  source(s) simultaneously.

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Explanations by astrophysical origins
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Possible origins of ee- pp interaction (Blasi,
0903.2794) Occur at the cosmic ray
acceleration source hard spectrum
Comment nature for Fermi spectrum antiprotons
may set constraints on this picture
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Nearby pulsars
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Astrophysical sources
D. Hooper et al. S. Profumo Y. Yuksel et al.

• Nearby pulsars

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From CRs interaction
Hu,Yuan,Wang,Fan,Zhang,Bi, 0901.1520

• There is knee in CR spectrum at 1015 eV
• It is proposed the knee is generated by
  interaction, with E?1eV, the threshold energy is
  at 1015 eV
• 3 converted can explain the Fermi excess

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• Astrophysical sources are easy to account for the
  Fermi spectrum, not easy for ATIC.

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Explanations by dark matter
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Primary positron/electrons from dark matter
implication from new data

• DM annihilation/decay produce leptons mainly in
  order not to produce too much antiprotons.
• Very hard electron spectrum -gt dark matter
  annihilates/decay into leptons.
• Very large annihilation cross section, much
  larger (1000) than the requirement by relic
  density. ( 1) nonthermal production, 2)
  Sommerfeld enhancement, 3) Breit-Wigner
  enhancement, 4) dark matter decay.)

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why should annihilate into leptons?
Yin, et al. arXiv0811.0176
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Dark matter models to produce leptons

• Kinematically suppression
• Mass of fis about 1GeV, is
• Kinematically suppressed to antiprotons
• At the same time attractive interaction can
  enhance the annihilaition rate, Sommerfeld
  enhancement. (Arkani-Hamed et al. 0810.0713  )
• Dynamically suppression, f carries U(1)e-µ(t)
  (Baek Fox Bi)
• DM models related with neutrino masses (Bi et al
  0901.0176 Cao et al. 0901.1334 )
• These models lead to hard positron spectrum and
  suppress antiproton flux naturally.

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Large flux

• Nonthermal production
• (from N. Weiner)
• Sommerfeld enhancement
• For attractive Coulomb Potential
• To enhance the dark matter annihilation we have
  long range attractive force

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Large flux
Ibe, Murayama, Yanagida Guo, Wu Bi, He, Yuan

• Breit-Wigner enhancement,

Bi, He, Yuan 0903.0122
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Decay dark matter with life time 1026s
Yin, Yuan, Liu, Zhang, Bi, Zhu, Zhang Chen,
Nojiri et al Ibarra, Tran Hamguchi, Shirai,
Yanagida
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How to discriminate different scenarios?
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Discrimination I. precise spectrum measurement of
ee-
Dark matter vs. pulsar sharp drop or not? (Hall
Hooper, 0811.3362)
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Discrimination I. precise electron spectrum
(continued)
Dark matter vs. pulsar fluctuations on the
spectrum? (Malyshev et al., 0903.1310)
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Discrimination II. anisotropy of electron flux
Diffuse vs. point (Hooper et al., 2009, JCAP,
01, 025)
A local dark matter clump may also behave like
this.
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Different models can work well

• Adjusting parameters, DM decay/annihilation,
  pulsars can all explain PAMELA and ATIC

Zhang, Bi, Liu, Liu, Yin, Yuan, Zhu, 0812.0522 
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Source distribution
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Can we test these scenarios?

• Detect the synchrotron and IC gamma ray signals
  from the GC.

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Diffuse gamma spectra
Fermi LAT
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Models independent constraint on the nature of
dark matter by the PAMELA and ATIC data
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Upper bounds on the WW and quark branching ratios
for DM annihilation
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Constraints on some DM models (1TeV)

• Neutralino, mainly into gauge bosons excluded
• In UED KK mode of U(1)Y gauge boson, 30 into
  quarks (universal KK mass) marginally allowed
• U(1)B-L, 40 into quarks, slightly disfavored
• Leptophilic models U(1)e-mu(tau), best fit
  data

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MCMC fit to the ATIC or Fermi and PAMELA data
Liu, Yuan, Bi, Li, Zhang, Astro-ph/0906.3858
Global fit to PAMELA, ATIC/Fermi, HESS data to
give best fit
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Constraints on the dark matter annihilation
scenario
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Emission from the GC
Bi et al., 0905.1253

• Constraint on the central density of DM
• Tension
• Exist for the
• annihilating
• DM scenario

Liu et al., 0906.3858
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Constraints on the minimal subhalos by
observations of clusters
A. Pinzke et al., 0905.1948

• Standard CDM predicts the minimal subhalos
• Observation constrains
• Fermi limit to
• DM is warm

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Constraints from extragalactic diffuse gamma rays

S. Profumo et al., 0906.0001
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Summary

• Anomalies observed in cosmic electrons and
  positrons discrepancy exists in data from
  different collaborations.
• Many works have been done related with these new
  results both astrophysical and DM scenarios are
  possible origins of these excesses.
• New data will come soon PAMELA finally detect
  positron to 270GeV antiproton to 190 GeV
  (published lt100GeV) total ee- to 2 TeV (not
  released) AMS02 launch at 2010 Re-flight of
  ATIC for electrons (AREL) was proposed to NASA
  Mar. 2009 Fermi results of diffuse gamma rays
  come soon
• LHC and DD help to determine nature of dark matter

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• O. Adriani et al., PAMELA Collaboration,
  arXiv0810.4995 298, Nature 458, 607 (2009)
• An anomalous positron abundance in cosmic
  rays with energies 1.5-100 GeV
• O. Adriani et al., PAMELA Collaboration,
  arXiv0810.4994 153, PRL102, 051101 (2009)
• A new measurement of the
  antiproton-to-proton flux ratio up to 100 GeV in
  the cosmic radiation
• J. Chang et al., ATIC Collaboration, Nature 456,
  362 (2008) 201
• An Excess of Cosmic Ray Electrons at
  Energies Of 300-800 GeV
• HESS Collaboration, arXiv0811.3894 86
  arXiv0905.0105 45, PRL
• Probing the ATIC peak in the cosmic-ray
  electron spectrum with H.E.S.S
• Fermi Collaboration, arXiv0905.0025 92
• Measurement of the Cosmic Ray e plus e-
  spectrum from 20 GeV to 1 TeV with the Fermi
  Large Area Telescope