2,350 research outputs found
A split SUSY model from SUSY GUT
We propose to split the sparticle spectrum from the hierarchy between the GUT
scale and the Planck scale. A split supersymmetric model, which gives
non-universal gaugino masses, is built with proper high dimensional operators
in the framework of SO(10) GUT. Based on a calculation of two-loop beta
functions for gauge couplings (taking into account all weak scale threshold
corrections), we check the gauge coupling unification and dark matter
constraints (relic density and direct detections). We find that our scenario
can achieve the gauge coupling unification and satisfy the dark matter
constraints in some part of parameter space. We also examine the sensitivity of
the future XENON1T experiment and find that the currently allowed parameter
space in our scenario can be covered for a neutralino dark matter below about
1.0 TeV.Comment: 16 pages, 3 figure; minor changes, references adde
Heavy colored SUSY partners from deflected anomaly mediation
We propose a deflected anomaly mediation scenario from SUSY QCD which can
lead to both positive and negative deflection parameters (there is a smooth
transition between these two deflection parameter regions by adjusting certain
couplings). Such a scenario can naturally give a SUSY spectrum in which all the
colored sparticles are heavy while the sleptons are light. As a result, the
discrepancy between the Brookheaven experiment and LHC data can be
reconciled in this scenario. We also find that the parameter space for
explaining the anomaly at level can be fully covered by the
future LUX-ZEPLIN 7.2 Ton experiment.Comment: 16 pages, 6 figure
Fast estimation of nonlinearities in atomic force microscopy
We propose a fast method to reconstruct the curve of tip-surface force v.s. distance
in Atomic Force Microscopy (AFM). A precise and fast force curve reconstruction can
help improve research in material science, biological science, chemistry, etc. Existing
techniques require multiple sinusoids at the input to introduce intermodulation terms,
i.e., exponential components at equally spaced frequencies, and the estimation is done
by balancing those terms. Instead of using intermodulation terms, our method tries to
balance time domain samples. The method is based on the assumption that a discrete
model approximates the continuous AFM model well when sampled at high frequency.
Least Squares method is used to derive a polynomial approximating the force curve.
The new method can make use of samples in the transient process and does not require
multiple sinusoids at the input. It has potential benets in taking less testing time,
getting more accuracy and acquiring force curves of several materials in one experiment
A comparative study of dark matter in the MSSM and its singlet extensions: a mini review
In this note we briefly review the recent studies of dark matter in the MSSM
and its singlet extensions: the NMSSM, the nMSSM, and the general singlet
extension. Under the new detection results of CDMS II, XENON, CoGeNT and
PAMELA, we find that (i) the latest detection results can exclude a large part
of the parameter space which allowed by current collider constraints in these
models. The future SuperCDMS and XENON can cover most of the allowed parameter
space; (ii) the singlet sector will decouple from the MSSM-like sector in the
NMSSM, however, singlet sector makes the nMSSM quite different from the MSSM;
(iii) the NMSSM can allow light dark matter at several GeV exists. Light
CP-even or CP-odd Higgs boson must be present so as to satisfy the measured
dark matter relic density. In case of the presence of a light CP-even Higgs
boson, the light neutralino dark matter can explain the CoGeNT and DAMA/LIBRA
results; (iv) the general singlet extension of the MSSM gives a perfect
explanation for both the relic density and the PAMELA result through the
Sommerfeld-enhanced annihilation. Higgs decays in different scenario are also
studied.Comment: Major changes. Reference added. To appear in Advances in High Energy
Physic
Multi-state Markov models with fixed and random effects
Multi-state models describe a process where individuals move among a series of states over time. They are increasingly popular in a wide range of applications in biostatistics. For instance, breast cancer, HIV and ageing problems. There are two types of effects when describing the hazards for change of status: fixed effects and random effects. For the fixed-effects multi-state model, the characteristics of individuals are usually considered as covariates, such as age and gender. However, there is still some unobserved heterogeneity, which can be taken into account as random effects. Models with both fixed effects and random effects in survival analysis are called frailty models. A large number of papers discusses parametric univariate frailties in multi-state models. This study presents both parametric and non-parametric frailty models. For the parametric frailty model, both univariate and bivariate frailties in multi-state models are discussed, in which frailties follow several common distributions. In particular, the contribution of this study is to apply a bivariate gamma-distributed frailty in the multi-state model for the interval-censored data, in order to describe the unobserved heterogeneity and investigate the correlation between two transition hazards. Model validation and prediction are discussed as well. In the application, we illustrate both fixed-effect models and frailty models for a cardiac allograft vasculopathy study and a cognitive impairment process
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