Revisiting Bremsstrahlung emission associated with Light Dark Matter annihilations

We compute the single bremsstrahlung emission associated with the pair annihilation of spin-0 particles into electrons and positrons, via the t-channel exchange of a heavy fermion. We compare our result with the work of Beacom et al. . Unlike what is stated in the literature, we show that the Bremsstrahlung cross section is not necessarily given by the tree-level annihilation cross section (for a generalized kinematics) times a factor related to the emission of a soft photon. Such a factorization appears only in the soft photon limit or in the approximation where the masses of the particles in the initial and final states are negligible with respect to the mass of the internal particle. However, in the latter case, we do not recover the same factor as for e^+ e- --> mu^+ mu^- gamma. Numerically the difference, in the hard photon limit, is as large as a factor 3.6. However the effect on the upper limit of the dark matter mass is not significant. Using gamma ray observations, we obtain an upper limit on the dark matter mass of 30 or 100 MeV (depending on the region that is considered for the 511 keV analysis) while Beacom et al. found 20 MeV

(Im)possibilities of Autonomy: Social Movements In and Beyond Capital, the State and Development

Recently, we have witnessed the emergence of what appears to be a new set of claims in contemporary social movements based around the idea of autonomy. In this paper we interrogate this demand for autonomy. In order to do this, we first engage with existing literatures, identifying three main conceptions of autonomy: 1) autonomous practices vis-à-vis capital, or, what Negri calls, the ‘self-valorization’ of labour; 2) self-determination and independence from the state; and 3) alternatives to hegemonic discourses of development. We will then problematize and point out the central potentials, weaknesses and antagonisms at the heart of the concept of autonomy. We argue that social movements’ demands for autonomy point to, what Laclau and Mouffe call, the impossibility of society, the idea that society can never be complete. That is, there will always be resistances, such as those expressed by autonomous social movements. However, this also lets us understand the conception of autonomy to be incomplete. Autonomy itself is hence an impossibility. To point to these limits of the discourses of autonomy, we discuss how demands for autonomy are tied up with contemporary re-organizations of: 1) the capitalist workplace, characterized by discourses of autonomy, creativity and self-management; 2) the state, which increasingly outsources public services to independent, autonomous providers, which often have a more radical, social movement history; and 3) regimes of development, which today often emphasize local practices, participation and self-determination. Behind these critical reflections on the conception and practice of autonomy is the idea that autonomy should always be seen as something relational. That is, autonomy can never be fixed; there is no definite ground for demands for autonomy to stand on. Instead, social movements’ demands for autonomy are embedded in specific social, economic, political and cultural contexts, giving rise to possibilities as well as impossibilities of autonomous practices

Light spin-1/2 or spin-0 Dark Matter particles

We recall and precise how light spin-0 particles could be acceptable Dark Matter candidates, and extend this analysis to spin-1/2 particles. We evaluate the (rather large) annihilation cross sections required, and show how they may be induced by a new light neutral spin-1 boson U. If this one is vectorially coupled to matter particles, the (spin-1/2 or spin-0) Dark Matter annihilation cross section into e+e- automatically includes a v_dm^2 suppression factor at threshold, as desirable to avoid an excessive production of gamma rays from residual Dark Matter annihilations. We also relate Dark Matter annihilations with production cross sections in e+e- scatterings. Annihilation cross sections of spin-1/2 and spin-0 Dark Matter particles are given by exactly the same expressions. Just as for spin-0, light spin-1/2 Dark Matter particles annihilating into e+e- could be responsible for the bright 511 keV gamma ray line observed by INTEGRAL from the galactic bulge.Comment: 10 page

Cosmological implications of a Dark Matter self-interaction energy density

We investigate cosmological constraints on an energy density contribution of elastic dark matter self-interactions characterized by the mass of the exchange particle and coupling constant. Because of the expansion behaviour in a Robertson-Walker metric we investigate self-interacting dark matter that is warm in the case of thermal relics. The scaling behaviour of dark matter self-interaction energy density shows that it can be the dominant contribution (only) in the very early universe. Thus its impact on primordial nucleosynthesis is used to restrict the interaction strength, which we find to be at least as strong as the strong interaction. Furthermore we explore dark matter decoupling in a self-interaction dominated universe, which is done for the self-interacting warm dark matter as well as for collisionless cold dark matter in a two component scenario. We find that strong dark matter self-interactions do not contradict super-weak inelastic interactions between self-interacting dark matter and baryonic matter and that the natural scale of collisionless cold dark matter decoupling exceeds the weak scale and depends linearly on the particle mass. Finally structure formation analysis reveals a linear growing solution during self-interaction domination; however, only non-cosmological scales are enhanced.Comment: 14 pages, 14 figures; version published in Phys. Rev.

Are small neutrino masses unveiling the missing mass problem of the Universe?

We present a scenario in which a remarkably simple relation linking dark matter properties and neutrino masses naturally emerges. This framework points towards a low energy theory where the neutrino mass originates from the existence of a light scalar dark matter particle in the MeV mass range. A very surprising aspect of this scenario is that the required MeV dark matter is one of the favoured candidates to explain the mysterious emission of 511 keV photons in the centre of our galaxy. A possible interpretation of these findings is that dark matter is the stepping stone of a theory beyond the standard model instead of being an embarrassing relic whose energy density must be accounted for in any successful model building.Comment: 4pages, 2 figures. Two paragraphs have been added. One for the complex case; the other one for the UV completio

First Rib Mobilization in the Treatment of Thoracic Outlet Syndrome

Background and Purpose: Thoracic outlet syndrome (TOS) is one of the most controversial clinical entities in medicine. It encompasses three related syndromes: compression of the brachial plexus (neurogenic TOS), compression of the subclavian artery or vein (vascular TOS), and a non-specific or disputed type of TOS.s Neurovascular compression may be observed most commonly in the interscalene triangle, but has also been described in the costoclavicular space and subcoracoid space.6 The purpose of this case study is to further explore the efficacy of manual therapy, specifically mobilization of the 1st rib, to relieve the symptoms of a 43 year old female, suffering from TOS. Case Description: The patient is a 43 year old female presenting with a tingling sensation around her left scapula and down her left arm after prolonged periods of relaxed sitting. Myotomes, dermatomes and reflexes were all negative, bilaterally. Adson\u27s maneuver and Roos test were both negative. Intervention: Moist hot pack and IFC were administered for 10 minutes for muscle relaxation. The patient was then asked to lay supine and her first ribs were palpated. A manual depression of the first rib was performed and repeated three times. This treatment was repeated six times over the course of two weeks, in addition to a home exercise program. Outcomes: The patient was seen three times per week for two and a half weeks for a total of eight treatment sessions. During the course of treatment, the patient reported a significant decrease in the frequency and severity of her symptoms. Once the therapist felt the patient had met her clinical goals, she was discharged with instructions to follow-up if any symptoms reoccurred. Discussion: This case study demonstrates manual depression of the 1st rib as an easy, effective option in the conservative management of thoracic outlet syndrome

Self-administration of edible Δ9-tetrahydrocannabinol and associated behavioral effects in mice

Background With increasing access to legal cannabis across the globe, it is imperative to more closely study its behavioral and physiological effects. Furthermore, with the proliferation of cannabis use, modes of consumption are changing, with edible formulations becoming increasingly popular. Nevertheless, there are relatively few animal models of self-administration of the primary psychoactive component of cannabis, Δ9-tetrahydrocannabinol (THC), and almost all incorporate routes of administration other than those used by humans. The aim of the current study was to develop a model of edible THC self-administration and assess its impact on CB1 receptor-mediated behaviors in female and male mice. Methods Mice were given limited access to a palatable dough which occasionally contained THC in doses ranging from 1 to 10 mg/kg. Following dough consumption, mice were assessed for home cage locomotor activity, body temperature, or analgesia. Locomotor activity was also assessed in conjunction with the CB1 receptor antagonist SR141716A. Results Dough was well-consumed, but consumption decreased at the highest THC concentrations. Edible THC produced dose-dependent decreases in locomotor activity and body temperature in both sexes, and these effects were more pronounced in male mice. Hypolocomotion induced by edible THC was attenuated by SR141716A, indicating mediation by CB1 receptor activation. Conclusions In contrast to other cannabinoid self-administration models, edible THC is relatively low in stress and uses a route of administration analogous to one used by humans. Potential applications include chronic THC self-administration, determining THC reward/reinforcement, and investigating consequences of oral THC use