Cosmic Ray Positrons at High Energies: A New Measurement

Barwick, S. W.; Beatty, J. J.; Bower, C.; Chaput, C.; Coutu, S.; Nolfo, G. de; Ficenec, D.; Knapp, J.; Lowder, D. M.; Kee, S. P. Mc; Müller, D.; Musser, J.; Nutter, S.; Schneider, E.; Swordy, S. P.; Tang, K. K.; Tarlè, G.; Tomasch, A.; Torbet, E.

doi:10.1103/physrevlett.75.390

Cited by 78 publications

(55 citation statements)

References 13 publications

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“…The PAMELA experiment has found an interesting rise in the positron fraction at energies up to 100 GeV (Adriani et al, 2009b), extending the previous results from the HEAT experiment (Barwick et al, 1995). This result has been corroborated by the measurements of the positron spectrum from the Fermi-LAT collaboration (Abdo et al, 2009b;Ackermann et al, 2012c) and HESS (Aharonian et al, 2009).…”

Section: Antimatter Searchessupporting

confidence: 76%

Galactic searches for dark matter

2013

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For nearly a century, more mass has been measured in galaxies than is contained in the luminous stars and gas. Through continual advances in observations and theory, it has become clear that the dark matter in galaxies is not comprised of known astronomical objects or baryonic matter, and that identification of it is certain to reveal a profound connection between astrophysics, cosmology, and fundamental physics. The best explanation for dark matter is that it is in the form of a yet undiscovered particle of nature, with experiments now gaining sensitivity to the most well-motivated particle dark matter candidates. In this article, I review measurements of dark matter in the Milky Way and its satellite galaxies and the status of Galactic searches for particle dark matter using a combination of terrestrial and space-based astroparticle detectors, and large scale astronomical surveys. I review the limits on the dark matter annihilation and scattering cross sections that can be extracted from both astroparticle experiments and astronomical observations, and explore the theoretical implications of these limits. I discuss methods to measure the properties of particle dark matter using future experiments, and conclude by highlighting the exciting potential for dark matter searches during the next decade, and beyond.

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Section: Antimatter Searchessupporting

confidence: 76%

Galactic searches for dark matter

2013

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“…There has been experimental evidence for an excess of positrons in the 10-100 GeV range for some time [82,83]. The recent data from the PAMELA experiment seems to confirm the previous results [84].…”

Section: Anti-matter In Cosmic Rayssupporting

confidence: 79%

Dark matter prospects in deflected mirage mediation

Holmes

Nelson

2009

J. Cosmol. Astropart. Phys.

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The recently introduced deflected mirage mediation (DMM) model is a string-motivated paradigm in which all three of the major supersymmetry-breaking transmission mechanisms are operative. We begin a systematic exploration of the parameter space of this rich model context, paying special attention to the pattern of gaugino masses which arise. In this work we focus on the dark matter phenomenology of the DMM model as such signals are the least influenced by the model-dependent scalar masses. We find that a large portion of the parameter space in which the three mediation mechanisms have a similar effective mass scale of 1 TeV or less will be probed by future direct and indirect detection experiments. Distinguishing deflected mirage mediation from the mirage model without gauge mediation will prove difficult without collider input, though we indicate how gamma ray signals may provide an opportunity for distinguishing between the two paradigms.

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“…Here, we comment on the positron excess recently reported by HEAT collaboration [34]. In the measurement, the excess of high energy positrons (1 GeV < E < 30 GeV) has been observed.…”

Section: Background Positronsmentioning

confidence: 93%

“…(34). There are six kinds of loop diagrams involving heavy gauge and NG bosons contributing to the T parameter as shown in Fig.9.…”

Section: Appendix Constraints From Electroweak Precision Measurementsmentioning

confidence: 99%

Cosmic positron signature from dark matter in the littlest Higgs model withTparity

et al. 2007

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We calculate the flux of cosmic positrons from the dark matter annihilation in the littlest Higgs model with T-parity. The dark matter annihilates mainly into weak gauge bosons in the halo, and high energy positrons are produced through leptonic and hadronic decays of the bosons. We investigate a possibility to detect the positron signal in upcoming experiments such as PAMELA and AMS-02. We found that the dark matter signal can be distinguished from the background in the PAMELA experiment when the dark matter mass is less than 120 GeV and the signal flux is enhanced due to a small scale clustering of dark matter. Furthermore, the signal from the dark matter annihilation can be detected in the AMS-02 experiment, even if such enhancement does not exist. We also discuss the invisible width of the Higgs boson in this model. 1 E-mail: masano@post.kek.jp 2 E-mail: smatsu@post.kek.jp 3 E-mail: okadan@post.kek.jp 4 E-mail: yasuhiro.okada@kek.jp I IntroductionThe hierarchy problem in the Standard Model (SM) is expected to give a clue to explore the physics beyond the SM. This problem is essentially related to quadratically divergent corrections to the Higgs boson mass, and we need a mechanism to avoid the divergences. To solve the problem, many scenarios have been proposed so far, for example supersymmetry, in which the divergences are completely removed.Other examples are scenarios with a low energy cutoff scale around a TeV such as Techni-color and TeV scale extra-dimension.The latter scenarios are, however, constrained by the electroweak precision measurements. From the analysis of higher dimensional operators at the cutoff scale, it has been found that the scale should be larger than roughly 5 TeV [1]. For such high energy cutoff, the hierarchy problem appears again: We still need the fine-tuning of a few percent level in the Higgs mass term in order to obtain the 100-200 GeV Higgs boson mass. This problem is called the little hierarchy problem.Recently the little Higgs model [2,3] has been proposed for solving the little hierarchy problem. In this scenario, the Higgs boson is regarded as a pseudo NambuGoldstone boson. New particles such as heavy gauge bosons and a top-partner are introduced, and all quadratic divergences to the Higgs mass term completely vanish at one-loop level due to these particles' contributions. Thus, the fine-tuning of the Higgs boson mass is avoided even if the cutoff scale is around 10 TeV.The original little Higgs model is still strongly constrained by the electroweak precision measurements [4]. This is mainly due to the contributions to electroweak observables from new heavy gauge bosons, because their masses are much smaller than the cutoff scale. In particular, direct couplings among a new heavy gauge boson and SM particles give sizable contributions to the observables. As a result, masses of new particles have to be raised, and the fine-tuning of the Higgs boson mass is reintroduced.To resolve the problem, the implementation of the Z 2 symmetry called T-parity to the model has b...

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Cosmic Ray Positrons at High Energies: A New Measurement

Cited by 78 publications

References 13 publications

Galactic searches for dark matter

Galactic searches for dark matter

Dark matter prospects in deflected mirage mediation

Cosmic positron signature from dark matter in the littlest Higgs model withTparity

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