388 research outputs found
Updated cosmic-ray and radio constraints on light dark matter: Implications for the GeV gamma-ray excess at the Galactic center
The apparent gamma-ray excess in the Galactic center region and inner Galaxy
has attracted considerable interest, notably because both its spectrum and
radial distribution are consistent with an interpretation in terms of
annihilating dark matter particles with a mass of about 10-40 GeV. We confront
such an interpretation with an updated compilation of various indirect dark
matter detection bounds, which we adapt to the specific form required by the
observed signal. We find that cosmic-ray positron data strongly rule out dark
matter annihilating to light leptons, or 'democratically' to all leptons, as an
explanation of the signal. Cosmic-ray antiprotons, for which we present
independent and significantly improved limits with respect to previous
estimates, are already in considerable tension with DM annihilation to any
combination of quark final states; the first set of AMS-02 data will thus be
able to rule out or confirm the DM hypothesis with high confidence. For
reasonable assumptions about the magnetic field in the Galactic center region,
radio observations independently put very severe constraints on a DM
interpretation of the excess, in particular for all leptonic annihilation
channels.Comment: 23 pages revtex, 19 figures, 1 table. Extended discussion of
antiproton limits and added references. Matches published versio
Enhanced Line Signals from Annihilating Kaluza-Klein Dark Matter
Monochromatic gamma ray lines have long been known to provide potential
smoking gun signals for annihilating dark matter. Here, we demonstrate that the
situation is particularly interesting for Kaluza-Klein dark matter because
resonant annihilation is generically expected for small, but not necessarily
vanishing relative velocities of the annihilating particles. We calculate the
contribution from those hitherto neglected resonances and show that the
annihilation rate into monochromatic photons can be significantly enhanced, in
a way that is much more pronounced than for the associated production of
continuum photons. For favorable astrophysical conditions, this leads to
promising prospects for the detection of TeV-scale Kaluza-Klein dark matter. We
also point out that the situation may be even more interesting in the vicinity
of black holes, like the supermassive black hole at the center of our Galaxy,
where in principle center-of-mass energies much larger than the rest mass are
available. In this case, annihilating Kaluza-Klein dark matter may show the
striking and unique signature of several gamma ray lines, with an equidistant
spacing corresponding to twice the compactification radius of the extra
dimension
Gamma Rays from Heavy Neutralino Dark Matter
We consider the gamma-ray spectrum from neutralino dark matter annihilations
and show that internal bremsstrahlung of W pair final states gives a previously
neglected source of photons at energies near the mass of the neutralino. For
masses larger than about 1 TeV, and for present day detector resolutions, this
results in a characteristic signal that may dominate not only over the
continuous spectrum from W fragmentation, but also over the \gamma-\gamma and
\gamma-Z line signals which are known to give large rates for heavy
neutralinos. Observational prospects thus seem promising.Comment: 4 pages, 4 figures; revised to match published versio
Kohnen's limit process for real-analytic Siegel modular forms
Kohnen introduced a limit process for Siegel modular forms that produces
Jacobi forms. He asked if there is a space of real-analytic Siegel modular
forms such that skew-holomorphic Jacobi forms arise via this limit process. In
this paper, we initiate the study of harmonic skew-Maass-Jacobi forms and
harmonic Siegel-Maass forms. We improve a result of Maass on the Fourier
coefficients of harmonic Siegel-Maass forms, which allows us to establish a
connection to harmonic skew-Maass-Jacobi forms. In particular, we answer
Kohnen's question in the affirmative.Comment: 19 pages, accepted for publication in Advances in Mathematic
Harmonic Maass-Jacobi forms with singularities and a theta-like decomposition
Real-analytic Jacobi forms play key roles in different areas of mathematics
and physics, but a satisfactory theory of such Jacobi forms has been lacking.
In this paper, we fill this gap by introducing a space of harmonic Maass-Jacobi
forms with singularities which includes the real-analytic Jacobi forms from
Zwegers's PhD thesis. We provide several structure results for the space of
such Jacobi forms, and we employ Zwegers's -functions to establish
a theta-like decomposition.Comment: 24 pages, To appear in Transactions of the AM
Impact of Meditation–Based Lifestyle Modification on HRV in Outpatients With Mild to Moderate Depression: An Exploratory Study
Background: The scientific evaluation of mind-body-interventions (MBI), including yoga and meditation, has increased significantly in recent decades. However, evidence of MBI's efficacy on biological parameters is still insufficient.
Objectives: In this study, we used HRV analysis to evaluate a novel MBI as a treatment of outpatients with mild to moderate depressive disorder. The Meditation-Based Lifestyle Modification (MBLM) program incorporates all major elements of classical yoga, including ethical principles of yoga philosophy, breathing exercises, postural yoga, and meditation.
Methods: In this exploratory randomized controlled trial, we compared the changes in HRV indices of a MBLM group (N = 22) and a minimal treatment group (MINIMAL, drugs only, N = 17) with those of a multimodal treatment-as-usual group (TAU, according to best clinical practice, N = 22). Electrocardiogram (ECG) recordings were derived from a Holter monitoring device, and HRV indices have been extracted from nearly stationary 20-min periods.
Results: Short-term HRV analysis revealed statistically significant differences in the pre-to-post changes between MBLM and TAU. In particular, the vagal tone mediating RMSSD and the Renyi entropy of symbolic dynamics indicated HRV gains in MBLM participants compared with TAU. Almost no alterations were observed in the MINIMAL group.
Conclusions: Our results suggest a benefit in selected HRV parameters for outpatients with mild to moderate depression participating in the MBLM program. For further investigations, we propose analysis of complete 24-h HRV recordings and additional continuous pulse wave or blood pressure analysis to assess long-term modulations and cardiovascular effects
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