13,159 research outputs found
Dark matter coupling to electroweak gauge and Higgs bosons: an effective field theory approach
If dark matter is a new species of particle produced in the early universe as
a cold thermal relic (a weakly-interacting massive particle-WIMP), its present
abundance, its scattering with matter in direct-detection experiments, its
present-day annihilation signature in indirect-detection experiments, and its
production and detection at colliders, depend crucially on the WIMP coupling to
standard-model (SM) particles. It is usually assumed that the WIMP couples to
the SM sector through its interactions with quarks and leptons. In this paper
we explore the possibility that the WIMP coupling to the SM sector is via
electroweak gauge and Higgs bosons. In the absence of an ultraviolet-complete
particle-physics model, we employ effective field theory to describe the
WIMP--SM coupling. We consider both scalars and Dirac fermions as possible
dark-matter candidates. Starting with an exhaustive list of operators up to
dimension 8, we present detailed calculation of dark-matter annihilations to
all possible final states, including gamma gamma, gamma Z, gamma h, ZZ, Zh, W+
W-, hh, and f fbar, and demonstrate the correlations among them. We compute the
mass scale of the effective field theory necessary to obtain the correct
dark-matter mass density, and well as the resulting photon line signals
Recommended from our members
Segmentation of P2P Accommodation Guests based on Their Experiences of Host Territoriality
P2P accommodation guests may experience host territoriality during their stay in home-sharing rentals, which would affect their experience satisfaction and future decision making. This study attempts to segment guests based on their experiences of host territoriality and assess the differences between these segments regarding host evaluations, experience satisfaction, behavioral intentions, and felt ownership of rental space. Three segments were identified, namely Space Owners, Space Users, and Space Borrowers, with Space Owners having lower scores in each dimension of host territoriality and Space Borrowers having higher scores in three out of four dimensions. Intrusion from the host seemed to be rare in P2P accommodation business. Compared with Space Users and Space Owners, Space Borrowers revealed lower levels of experience satisfaction and felt ownership of rental space, evaluated hosts to be less warm, trustworthy, and competent, and were less likely to reuse P2P accommodation rentals
Recommended from our members
Health and economic benefits of building ventilation interventions for reducing indoor PM2.5 exposure from both indoor and outdoor origins in urban Beijing, China
China is confronted with serious PM2.5 pollution, especially in the capital city of Beijing. Exposure to PM2.5 could lead to various negative health impacts including premature mortality. As people spend most of their time indoors, the indoor exposure to PM2.5 from both indoor and outdoor origins constitutes the majority of personal exposure to PM2.5 pollution. Different building interventions have been introduced to mitigate indoor PM2.5 exposure, but always at the cost of energy expenditure. In this study, the health and economic benefits of different ventilation intervention strategies for reducing indoor PM2.5 exposure are modelled using a representative urban residence in Beijing, with consideration of different indoor PM2.5 emission strengths and outdoor pollution. Our modelling results show that the increase of envelope air-tightness can achieve significant economic benefits when indoor PM2.5 emissions are absent; however, if an indoor PM2.5 source is present, the benefits only increase slightly in mechanically ventilated buildings, but may show negative benefit without mechanical ventilation. Installing mechanical ventilation in Beijing can achieve annual economic benefits ranging from 200yuan/capita to 800yuan/capita if indoor PM2.5 sources exist. If there is no indoor emission, the annual benefits above 200yuan/capita can be achieved only when the PM2.5 filtration efficiency is no less than 90% and the envelope air-tightness is above Chinese National Standard Level 7. Introducing mechanical ventilation with low PM2.5 filtration efficiency to current residences in urban Beijing will increase the indoor PM2.5 exposure and result in excess costs to the resident
- …