13,015 research outputs found
Studying Double Charm Decays of B_{u,d} and B_{s} Mesons in the MSSM with R-parity Violation
Motivated by the possible large direct CP asymmetry of \bar{B}^0_d \to D^+
D^- decay measured by Belle collaboration, we investigate double charm B_{u,d}
and B_s decays in the minimal supersymmetric standard model with R-parity
violation. We derive the bounds on relevant R-parity violating couplings from
the current experimental data, which show quite consistent measurements among
relative collaborations. Using the constrained parameter spaces, we explore
R-parity violating effects on other observables in these decays, which have not
been measured or have not been well measured yet. We find that the R-parity
violating effects on the mixing-induced CP asymmetries of \bar{B}^0_d \to
D^{(*)+} D^{(*)-} and \bar{B}^0_s \to D^{(*)+}_s D^{(*)-}_s decays could be
very large, nevertheless the R-parity violating effects on the direct CP
asymmetries could not be large enough to explain the large direct CP violation
of \bar{B}^0_d \to D^{+} D^{-} from Belle. Our results could be used to probe
R-parity violating effects and will correlate with searches for direct R-parity
violating signals in future experiments.Comment: 28 pages and 6 figures, matches published versio
The D0 same-charge dimuon asymmetry and possibile new CP violation sources in the system
Recently, the D0 collaboration reported a large CP violation in the same-sign
dimuon charge asymmetry which has the deviation from the value
estimated in the Standard Model. In this paper, several new physics models are
considered: the MSSM, two Higgs doublet model, the recent dodeca model, and a
new model. Generally, it is hard to achieve such a large CP violation
consistently with other experimental constraints. We find that a scheme with
extra non-anomalous U(1) gauge symmetry is barely consistent. In general,
the extra gauge boson induces the flavor changing neutral current
interactions at tree level, which is the basic reason allowing a large new
physics CP violation. To preserve the U(1) symmetry at high energy,
SU(2) singlet exotic heavy quarks of mass above 1 TeV and the Standard
Model gauge singlet scalars are introduced.Comment: 12 pages, 13 figure
A Tractable Model of the LTE Access Reservation Procedure for Machine-Type Communications
A canonical scenario in Machine-Type Communications (MTC) is the one
featuring a large number of devices, each of them with sporadic traffic. Hence,
the number of served devices in a single LTE cell is not determined by the
available aggregate rate, but rather by the limitations of the LTE access
reservation protocol. Specifically, the limited number of contention preambles
and the limited amount of uplink grants per random access response are crucial
to consider when dimensioning LTE networks for MTC. We propose a low-complexity
model of LTE's access reservation protocol that encompasses these two
limitations and allows us to evaluate the outage probability at click-speed.
The model is based chiefly on closed-form expressions, except for the part with
the feedback impact of retransmissions, which is determined by solving a fixed
point equation. Our model overcomes the incompleteness of the existing models
that are focusing solely on the preamble collisions. A comparison with the
simulated LTE access reservation procedure that follows the 3GPP
specifications, confirms that our model provides an accurate estimation of the
system outage event and the number of supported MTC devices.Comment: Submitted, Revised, to be presented in IEEE Globecom 2015; v3: fixed
error in eq. (4
Semiconductor nanoring lasers
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98671/1/ApplPhysLett_98_201105.pd
Lasing in a metal-clad microring resonator
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98661/1/ApplPhysLett_98_131107.pd
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