5,142 research outputs found
Lepton-portal Dark Matter in Hidden Valley model and the DAMPE recent results
We study the recent cosmic ray excess reported by DAMPE in a Hidden
Valley Model with lepton-portal dark matter. We find the electron-portal can
account for the excess well and satisfy the DM relic density and direct
detection bounds, while electron+muon/electron+muon+tau-portal suffers from
strong constraints from lepton flavor violating observables, such as . We also discuss possible collider signatures of our model, both at the LHC
and a future 100 TeV hadron collider.Comment: invited by Science China, accepted versio
Utility Maximization for Uplink MU-MIMO: Combining Spectral-Energy Efficiency and Fairness
Driven by green communications, energy efficiency (EE) has become a new
important criterion for designing wireless communication systems. However, high
EE often leads to low spectral efficiency (SE), which spurs the research on
EE-SE tradeoff. In this paper, we focus on how to maximize the utility in
physical layer for an uplink multi-user multiple-input multipleoutput (MU-MIMO)
system, where we will not only consider EE-SE tradeoff in a unified way, but
also ensure user fairness. We first formulate the utility maximization problem,
but it turns out to be non-convex. By exploiting the structure of this problem,
we find a convexization procedure to convert the original nonconvex problem
into an equivalent convex problem, which has the same global optimum with the
original problem. Following the convexization procedure, we present a
centralized algorithm to solve the utility maximization problem, but it
requires the global information of all users. Thus we propose a primal-dual
distributed algorithm which does not need global information and just consumes
a small amount of overhead. Furthermore, we have proved that the distributed
algorithm can converge to the global optimum. Finally, the numerical results
show that our approach can both capture user diversity for EE-SE tradeoff and
ensure user fairness, and they also validate the effectiveness of our
primal-dual distributed algorithm
Simplified TeV leptophilic dark matter in light of DAMPE data
Using a simplified framework, we attempt to explain the recent DAMPE cosmic
flux excess by leptophilic Dirac fermion dark matter (LDM). The
scalar () and vector () mediator fields connecting LDM and
Standard Model particles are discussed. Under constraints of DM relic density,
gamma-rays, cosmic-rays and Cosmic Microwave Background (CMB), we find that the
couplings , , and can
produce the right bump in flux for a DM mass around 1.5 TeV with a
natural thermal annihilation cross-section today. Among them, coupling is tightly constrained by
PandaX-II data (although LDM-nucleus scattering appears at one-loop level) and
the surviving samples appear in the resonant region, . We also study the related collider signatures, such as dilepton
production , and muon anomaly. Finally,
we present a possible realization for such leptophilic dark matter.Comment: discussions added, version accepted by JHE
- β¦