Positron Excess in a Sentence

We revisit dark matter annihilation as an explanation of the positron excess reported recently by the AMS-02 satellite-borne experiment.

This has important implication for the interpretation of the CR positron excess.

This is called ‘positron excess’ whose origin remains unknown, and interpretations including supernova remnants, pulsar wind nebulae (PWNe) or dark matter have been considered.

Sommerfeld-enhanced dark matter (DM) annihilation through s-wave has been widely considered as a consistent explanation for both the observed cosmic-ray (CR) positron excess and the DM thermal relic density.

In this paper, we instead examine the potential for extremely precise positron measurements by AMS-02 to probe hard leptophilic dark matter candidates that do not have spectral features similar to the bulk of the observed positron excess.

Despite significant efforts over the last decade, the origin of the cosmic ray positron excess has still not been unambiguously established.

In particular, the AMS-02 anti-proton and positron excesses have continued to grow more robust with the collection of more data.

As a consequence, the most likely pulsar source of the positron excess, Geminga, is no more a viable candidate under the additional constraint from Fermi-LAT.

With experimental results of AMS on the spectra of cosmic ray (CR) $e^{-}$, $e^{+}$, $e^{-}+e^{+}$ and positron fraction, as well as new measurements of CR $e^{-}+e^{+}$ flux by HESS, one can better understand the CR lepton ($e^{-}$ and $e^{+}$) spectra and the puzzling electron-positron excess above $\sim$10 GeV.

This result also constrains the modeling of the positron excesses.

Our results are compatible with the interpretation that the cumulative emission from Galactic pulsars explains the positron excess.

One possible explanation can be that positron excess is generated by ~ TeV dark matter particles annihilation or decay.

It includes effects in cosmic rays (CR): first of all, the positron excess at $\sim$ 500 GeV and possible electron-positron excess at 1-1.

Our findings must be reckoned with theories of Galactic CR transport, which often assume that electrons and protons are injected with the same slope, and may especially have implications for the observed "positron excess".

The positron excess observed by PAMELA and then confirmed by AMS 02 has intrigued the particle physics community since 2008.

Recent (and earlier) analyses of the data from Planck, Fermi-LAT, AMS-02, and other experiments indicate that (i) the positron excess at ∼ 800 GeV or above is not evidence of highmass dark matter particles (which would have disconfirmed the present theory with a rigorous upper limit of 125 GeV), (ii) the Galactic center excess of gamma rays observed by Fermi is evidence for dark matter particles with a mass below or near 100 GeV, (iii) the gamma-ray excess from Omega Centauri is similar evidence of annihilation of such relatively low-mass particles, and (iv) the antiproton excess observed by AMS is again evidence of.

By modeling the TeV emission as inverse Compton emission from electron-positron pairs diffusing in the interstellar medium (ISM), the HAWC collaboration derives a diffusion coefficient much smaller than the standard value in the vicinity of the two pulsars, which make them unlikely the origin of the positron excess.

We study the gauged $U(1)_{L_\mu-L_\tau}$ scotogenic model with emphasis on latest measurement of LHCb $R_{K^{(*)}}$ anomaly and AMS-02 positron excess.

In the light of the latest measurements on the total $e^+ + e^-$ flux by CALET and DAMPE experiments, we revisit the multicomponent leptonically decaying dark matter (DM) explanations to the cosmic-ray electron/positron excesses observed previously.

After including these GMCs we show that the positron excess can be mostly well explained, with a small contribution from unknown extra component near the peak.

With experimental results of AMS on the spectra of cosmic ray (CR) e^−, e^+, e^− + e^+ and positron fraction, as well as new measurements of CR e^− + e^+ flux by HESS, one can better understand the CR lepton (e^− and e^+) spectra and the puzzling electron–positron excess above ∼10 GeV.

In this contribution we present a detailed study of the GeV gamma-ray halo around Geminga and Monogem, and show the constraints found for the contribution of these PWNe to the cosmic-ray positron excess, combining Milagro and HAWC data with measurements from the Fermi-LAT for the first time.