8,336 research outputs found
Probing gauge-phobic heavy Higgs bosons at high energy hadron colliders
We study the probe of the gauge-phobic (or nearly gauge-phobic) heavy Higgs
bosons (GPHB) at high energy hadron colliders including the 14 TeV LHC and the
50 TeV Super Proton-Proton Collider (SppC). We take the process , and study it at the hadron level including simulating the jet
formation and top quark tagging (with jet substructure). We show that, for a
GPHB with GeV, can be determined by adjusting the value
of in the theoretical distribution to fit the observed
distribution, and the resonance peak can be seen at the SppC for
=800 GeV and 1 TeV.Comment: 6 pages, with 7 eps files for 7 figure
Open vs Closed Access Femtocells in the Uplink
Femtocells are assuming an increasingly important role in the coverage and
capacity of cellular networks. In contrast to existing cellular systems,
femtocells are end-user deployed and controlled, randomly located, and rely on
third party backhaul (e.g. DSL or cable modem). Femtocells can be configured to
be either open access or closed access. Open access allows an arbitrary nearby
cellular user to use the femtocell, whereas closed access restricts the use of
the femtocell to users explicitly approved by the owner. Seemingly, the network
operator would prefer an open access deployment since this provides an
inexpensive way to expand their network capabilities, whereas the femtocell
owner would prefer closed access, in order to keep the femtocell's capacity and
backhaul to himself. We show mathematically and through simulations that the
reality is more complicated for both parties, and that the best approach
depends heavily on whether the multiple access scheme is orthogonal (TDMA or
OFDMA, per subband) or non-orthogonal (CDMA). In a TDMA/OFDMA network,
closed-access is typically preferable at high user densities, whereas in CDMA,
open access can provide gains of more than 200% for the home user by reducing
the near-far problem experienced by the femtocell. The results of this paper
suggest that the interests of the femtocell owner and the network operator are
more compatible than typically believed, and that CDMA femtocells should be
configured for open access whereas OFDMA or TDMA femtocells should adapt to the
cellular user density.Comment: 21 pages, 8 figures, 2 tables, submitted to IEEE Trans. on Wireless
Communication
Fundamentals of Inter-cell Overhead Signaling in Heterogeneous Cellular Networks
Heterogeneous base stations (e.g. picocells, microcells, femtocells and
distributed antennas) will become increasingly essential for cellular network
capacity and coverage. Up until now, little basic research has been done on the
fundamentals of managing so much infrastructure -- much of it unplanned --
together with the carefully planned macro-cellular network. Inter-cell
coordination is in principle an effective way of ensuring different
infrastructure components behave in a way that increases, rather than
decreases, the key quality of service (QoS) metrics. The success of such
coordination depends heavily on how the overhead is shared, and the rate and
delay of the overhead sharing. We develop a novel framework to quantify
overhead signaling for inter-cell coordination, which is usually ignored in
traditional 1-tier networks, and assumes even more importance in multi-tier
heterogeneous cellular networks (HCNs). We derive the overhead quality contour
for general K-tier HCNs -- the achievable set of overhead packet rate, size,
delay and outage probability -- in closed-form expressions or computable
integrals under general assumptions on overhead arrivals and different overhead
signaling methods (backhaul and/or wireless). The overhead quality contour is
further simplified for two widely used models of overhead arrivals: Poisson and
deterministic arrival process. This framework can be used in the design and
evaluation of any inter-cell coordination scheme. It also provides design
insights on backhaul and wireless overhead channels to handle specific overhead
signaling requirements.Comment: 21 pages, 9 figure
Novel Non-equilibrium Phase Transition Caused by Non-linear Hadronic-quark Phase Structure
We consider how the occurrence of first-order phase transitions in
non-constant pressure differs from those at constant pressure. The former has
shown the non-linear phase structure of mixed matter, which implies a particle
number dependence of the binding energies of the two species. If the mixed
matter is mixed hadron-quark phase, nucleon outgoing from hadronic phase and
ingoing to quark phase probably reduces the system to a non-equilibrium state,
in other words, there exists the imbalance of the two phases when deconfinement
takes place. This novel non-equilibrium process is very analogous to the
nuclear reactions that nuclei emit neutrons and absorb them under appropriate
conditions. We present self-consistent thermodynamics in description for the
processes and identify the microphysics responsible for the processes. The
microphysics is an inevitable consequence of non-linear phase structure instead
of the effect of an additional dissipation force. When applying our findings to
the neutron star containing mixed hadron-quark matter, it is found that the
newly discovered energy release might strongly change the thermal evolution
behavior of the star.Comment: 18pages,3figures;to be accepted for publication in Physics Letters
Open, Closed, and Shared Access Femtocells in the Downlink
A fundamental choice in femtocell deployments is the set of users which are
allowed to access each femtocell. Closed access restricts the set to
specifically registered users, while open access allows any mobile subscriber
to use any femtocell. Which one is preferable depends strongly on the distance
between the macrocell base station (MBS) and femtocell. The main results of the
paper are lemmas which provide expressions for the SINR distribution for
various zones within a cell as a function of this MBS-femto distance. The
average sum throughput (or any other SINR-based metric) of home users and
cellular users under open and closed access can be readily determined from
these expressions. We show that unlike in the uplink, the interests of home and
cellular users are in conflict, with home users preferring closed access and
cellular users preferring open access. The conflict is most pronounced for
femtocells near the cell edge, when there are many cellular users and fewer
femtocells. To mitigate this conflict, we propose a middle way which we term
shared access in which femtocells allocate an adjustable number of time-slots
between home and cellular users such that a specified minimum rate for each can
be achieved. The optimal such sharing fraction is derived. Analysis shows that
shared access achieves at least the overall throughput of open access while
also satisfying rate requirements, while closed access fails for cellular users
and open access fails for the home user.Comment: 26 pages, 8 figures, Submitted to IEEE Transactions on Wireless
Communication
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