12,543 research outputs found
The Leptoquark Hunter's Guide: Large Coupling
Leptoquarks have recently received much attention especially because they may
provide an explanation to the and anomalies in rare
meson decays. In a previous paper we proposed a systematic search strategy
for all possible leptoquark flavors by focusing on leptoquark pair production.
In this paper, we extend this strategy to large (order unity) leptoquark
couplings which offer new search opportunities: single leptoquark production
and -channel leptoquark exchange with dilepton final states. We discuss the
unique features of the different search channels and show that they cover
complementary regions of parameter space. We collect and update all currently
available bounds for the different flavor final states from LHC searches and
from atomic parity violation measurements. As an application of our analysis,
we find that current limits do not exclude the leptoquark explanation of the
physics anomalies but that the high luminosity run of the LHC will reach
the most interesting parameter space.Comment: 33 pages + references, 15 figures, 9 tables, v2: references adde
Hamiltonian lattice quantum chromodynamics at finite density with Wilson fermions
Quantum chromodynamics (QCD) at sufficiently high density is expected to
undergo a chiral phase transition. Understanding such a transition is of
particular importance for neutron star or quark star physics. In Lagrangian
SU(3) lattice gauge theory, the standard approach breaks down at large chemical
potential , due to the complex action problem. The Hamiltonian formulation
of lattice QCD doesn't encounter such a problem. In a previous work, we
developed a Hamiltonian approach at finite chemical potential and
obtained reasonable results in the strong coupling regime. In this paper, we
extend the previous work to Wilson fermions. We study the chiral behavior and
calculate the vacuum energy, chiral condensate and quark number density, as
well as the masses of light hadrons. There is a first order chiral phase
transition at zero temperature.Comment: 23 pages. Version accepted for publication in Physical Review
Multi-channel Hybrid Access Femtocells: A Stochastic Geometric Analysis
For two-tier networks consisting of macrocells and femtocells, the channel
access mechanism can be configured to be open access, closed access, or hybrid
access. Hybrid access arises as a compromise between open and closed access
mechanisms, in which a fraction of available spectrum resource is shared to
nonsubscribers while the remaining reserved for subscribers. This paper focuses
on a hybrid access mechanism for multi-channel femtocells which employ
orthogonal spectrum access schemes. Considering a randomized channel assignment
strategy, we analyze the performance in the downlink. Using stochastic geometry
as technical tools, we model the distribution of femtocells as Poisson point
process or Neyman-Scott cluster process and derive the distributions of
signal-to-interference-plus-noise ratios, and mean achievable rates, of both
nonsubscribers and subscribers. The established expressions are amenable to
numerical evaluation, and shed key insights into the performance tradeoff
between subscribers and nonsubscribers. The analytical results are corroborated
by numerical simulations.Comment: This is the final version, which was accepted in IEEE Transactions on
Communication
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