17,930 research outputs found
750 GeV Resonance in the Gauged -Extended MSSM
Recently the ATLAS and CMS collaborations at the LHC announced their
observation of a potential 750 GeV di-photon resonance, after analyzing the
TeV LHC data. This observation has significant implications for
low-energy supersymmetry. Beyond the MSSM and the NMSSM, we study the
MSSM-extensions with an extra gauge symmetry. The anomaly cancellation
and the spontaneous breaking of the non-decoupled generically require
introducing vector-like supermultiplets (both colored and color-neutral ones)
and singlet supermultiplets, respectively. We illustrate that the potential 750
GeV resonance () can be accommodated in various mechanisms, as a
singlet-like scalar or pseudoscalar. Three benchmark scenarios are presented:
(1) vector-like quarks (VLQ) mediated ; (2) scalar
VLQ mediated ; (3) heavy scalar (pseudo-scalar)
associated production . Additionally, we notice
that the -mediated vector boson fusion production and -associated
production , if yielding a signal rate of the observed level,
might have been excluded by the searches for via Drell-Yan process at the
LHC.Comment: v3, figure update with corresponding modification in discussion,
version accepted by PL
Deterministic Constructions of Binary Measurement Matrices from Finite Geometry
Deterministic constructions of measurement matrices in compressed sensing
(CS) are considered in this paper. The constructions are inspired by the recent
discovery of Dimakis, Smarandache and Vontobel which says that parity-check
matrices of good low-density parity-check (LDPC) codes can be used as
{provably} good measurement matrices for compressed sensing under
-minimization. The performance of the proposed binary measurement
matrices is mainly theoretically analyzed with the help of the analyzing
methods and results from (finite geometry) LDPC codes. Particularly, several
lower bounds of the spark (i.e., the smallest number of columns that are
linearly dependent, which totally characterizes the recovery performance of
-minimization) of general binary matrices and finite geometry matrices
are obtained and they improve the previously known results in most cases.
Simulation results show that the proposed matrices perform comparably to,
sometimes even better than, the corresponding Gaussian random matrices.
Moreover, the proposed matrices are sparse, binary, and most of them have
cyclic or quasi-cyclic structure, which will make the hardware realization
convenient and easy.Comment: 12 pages, 11 figure
Echoes of Inflationary First-Order Phase Transitions in the CMB
Cosmological phase transitions (CPTs), such as the Grand Unified Theory (GUT)
and the electroweak (EW) ones, play a significant role in both particle physics
and cosmology. In this letter, we propose to probe the first-order CPTs, by
detecting gravitational waves (GWs) which are generated during the phase
transitions through the cosmic microwave background (CMB). If happened around
the inflation era, the first-order CPTs may yield low-frequency GWs due to
bubble dynamics, leaving imprints on the CMB. In contrast to the nearly
scale-invariant primordial GWs caused by vacuum fluctuation, these
bubble-generated GWs are scale dependent and have non-trivial B-mode spectra.
If decoupled from inflaton, the EWPT during inflation may serve as a probe for
the one after reheating where the baryon asymmetry could be generated via EW
baryogenesis (EWBG). The CMB thus provides a potential way to test the
feasibility of the EWBG, complementary to the collider measurements of Higgs
potential and the direct detection of GWs generated during EWPT.Comment: 5+6 pages, 4 figures. V2 changed title, added one figure about
constraints of Planck2015+BICEP2/Keck data, added references and removed
appendix. Accepted by PL
A pathway analysis of genome-wide association study highlights novel type 2 diabetes risk pathways.
Genome-wide association studies (GWAS) have been widely used to identify common type 2 diabetes (T2D) variants. However, the known variants just explain less than 20% of the overall estimated genetic contribution to T2D. Pathway-based methods have been applied into T2D GWAS datasets to investigate the biological mechanisms and reported some novel T2D risk pathways. However, few pathways were shared in these studies. Here, we performed a pathway analysis using the summary results from a large-scale meta-analysis of T2D GWAS to investigate more genetic signals in T2D. Here, we selected PLNK and VEGAS to perform the gene-based test and WebGestalt to perform the pathway-based test. We identified 8 shared KEGG pathways after correction for multiple tests in both methods. We confirm previous findings, and highlight some new T2D risk pathways. We believe that our results may be helpful to study the genetic mechanisms of T2D
Spectral Efficiency Analysis of Multi-Cell Massive MIMO Systems with Ricean Fading
This paper investigates the spectral efficiency of multi-cell massive
multiple-input multiple-output systems with Ricean fading that utilize the
linear maximal-ratio combining detector. We firstly present closed-form
expressions for the effective signal-to-interference-plus-noise ratio (SINR)
with the least squares and minimum mean squared error (MMSE) estimation
methods, respectively, which apply for any number of base-station antennas
and any Ricean -factor. Also, the obtained results can be particularized in
Rayleigh fading conditions when the Ricean -factor is equal to zero. In the
following, novel exact asymptotic expressions of the effective SINR are derived
in the high and high Ricean -factor regimes. The corresponding analysis
shows that pilot contamination is removed by the MMSE estimator when we
consider both infinite and infinite Ricean -factor, while the pilot
contamination phenomenon persists for the rest of cases. All the theoretical
results are verified via Monte-Carlo simulations.Comment: 15 pages, 2 figures, the tenth International Conference on Wireless
Communications and Signal Processing (WCSP 2018), to appea
Pilot Power Allocation Through User Grouping in Multi-Cell Massive MIMO Systems
In this paper, we propose a relative channel estimation error (RCEE) metric,
and derive closed-form expressions for its expectation and
the achievable uplink rate holding for any number of base station antennas ,
with the least squares (LS) and minimum mean squared error (MMSE) estimation
methods. It is found that RCEE and converge to the same
constant value when , resulting in the pilot power
allocation (PPA) is substantially simplified and a PPA algorithm is proposed to
minimize the average per user with a total pilot power
budget in multi-cell massive multiple-input multiple-output systems.
Numerical results show that the PPA algorithm brings considerable gains for the
LS estimation compared with equal PPA (EPPA), while the gains are only
significant with large frequency reuse factor (FRF) for the MMSE estimation.
Moreover, for large FRF and large , the performance of the LS approaches to
the performance of the MMSE, which means that simple LS estimation method is a
very viable when co-channel interference is small. For the achievable uplink
rate, the PPA scheme delivers almost the same average achievable uplink rate
and improves the minimum achievable uplink rate compared with the EPPA scheme.Comment: 30 pages, 5 figures, submitted to IEEE Transactions on Communication
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