arXiv subjects

Yue Zhang

Publications and source records attributed to Yue Zhang.

At least 847 records · Page 47Linked to original sources

arXiv2014

Performance of ML Range Estimator in Radio Interferometric Positioning Systems

The radio interferometric positioning system (RIPS) is a novel positioning solution used in wireless sensor networks. This letter explores the ranging accuracy of RIPS in two configurations. In the linear step-frequency (LSF) configuration, we derive the mean square error (MSE) of the maximum likelihood (ML) estimator. In the random step-frequency (RSF) configuration, we introduce average MSE to characterize the performance of the ML estimator. The simulation results fit well with theoretical analysis. It is revealed that RSF is superior to LSF in that the former is more robust in a jamming environment with similar ranging accuracy.

cs.IT↗

arXiv2014

Constructing Gazetteers from Volunteered Big Geo-Data Based on Hadoop

Traditional gazetteers are built and maintained by authoritative mapping agencies. In the age of Big Data, it is possible to construct gazetteers in a data-driven approach by mining rich volunteered geographic information (VGI) from the Web. In this research, we build a scalable distributed platform and a high-performance geoprocessing workflow based on the Hadoop ecosystem to harvest crowd-sourced gazetteer entries. Using experiments based on geotagged datasets in Flickr, we find that the MapReduce-based workflow running on the spatially enabled Hadoop cluster can reduce the processing time compared with traditional desktop-based operations by an order of magnitude. We demonstrate how to use such a novel spatial-computing infrastructure to facilitate gazetteer research. In addition, we introduce a provenance-based trust model for quality assurance. This work offers new insights on enriching future gazetteers with the use of Hadoop clusters, and makes contributions in connecting GIS to the cloud computing environment for the next frontier of Big Geo-Data analytics.

cs.DC↗

arXiv2013

Impact of a CP Violating Higgs: from LHC to Baryogenesis

We observe a generic connection between LHC Higgs data and electroweak baryogenesis: the particle that contributes to the CP odd $hgg$ or $h γγ$ vertex would provide the CP violating source during a first order phase transition. It is illustrated in the 2HDM that a common complex phase controls the lightest Higgs properties at the LHC, electric dipole moments and the CP violating source for electroweak baryogenesis. We perform a general parametrization of Higgs effective couplings and a global fit to the LHC Higgs data. Current LHC measurements prefer a nonzero phase for $\tan β\lesssim 1$ and EDM constraints still allow an order one phase for $\tanβ\sim1$, which gives sufficient room to generate the correct cosmic baryon asymmetry. We also give some prospects in the direct measurements of CP violation in the Higgs sector at the LHC.

hep-ph↗

arXiv2013

Baryogenesis Once More, Inside LHC

We investigate the feasibility of directly detecting a generation mechanism of the cosmic baryon asymmetry, by repeating the same particle physics process inside the LHC. We propose a framework with R-parity and CP violating squark decays responsible for baryogenesis, which can be embedded in supersymmetric models and is partly motivated by naturalness. We argue that the baryon number generation here is closely related to lepton charge asymmetry on the resonance. We emphasize the importance of the single charged lepton plus multijet channel in the absence of significant missing energy in search of such a scenario.

hep-ph↗

arXiv2013

On the Higgs Fit and Electroweak Phase Transition

We consider the Higgs portal through which light scalars contribute both to the Higgs production and decay and Higgs effective potential at finite temperature via quantum loops. The positive Higgs portal coupling required by a strongly first order electroweak phase transition is disfavored by the current Higgs data if we consider one such scalar. We observe that by introducing a second scalar with negative Higgs portal coupling, one can not only improve the Higgs fits, but also enhance the strength of first order EWPT. We apply this mechanism to the light stop scenario for electroweak baryogenesis in the MSSM and find a light sbottom could play the role as the second scalar, which allows the stop to be relatively heavier. Non-decoupled effects on the Higgs or sbottom self-interactions from physics beyond MSSM is found to be indispensable for this scenario to work. A clear prediction from the picture is the existence of a light sbottom (below 200 GeV) and a light stop (can be as heavy as 140 GeV), which can be directly tested in the near future.

hep-ph↗

arXiv2013

Electroweak Cogenesis

We propose a simple renormalizable model of baryogenesis and asymmetric dark matter generation at the electroweak phase transition. Our setup utilizes the two Higgs doublet model plus two complex gauge singlets, the lighter of which is stable dark matter. The dark matter is charged under a global symmetry that is broken in the early universe but restored during the electroweak phase transition. Because the ratio of baryon and dark matter asymmetries is controlled by model parameters, the dark matter need not be light. Thus, new force carriers are unnecessary and the symmetric dark matter abundance can be eliminated via Higgs portal interactions alone. Our model places a rough upper bound on the dark matter mass, and has implications for direct detection experiments and particle colliders.

hep-ph↗

arXiv2013

Top Quark Mediated Dark Matter

We study the top quark portal dominated dark matter interactions, and its implications for the gamma ray line searches. In this picture, the dark matter interactions with photons and gluons are loop induced by the axial anomaly of the top quark current. We show there can be a natural suppression of the tree-level annihilation of dark matter, and the photon channel in turn has a substantial rate when the main annihilation proceeds into gluons. We observe a competition between the indirect detection of gamma ray line and the search with monojet plus missing energy events at LHC, and the 7 TeV data already set an upper bound of ~ 10^{-28} cm^3/s on the photonic annihilation cross section. This upper limit is compatible with a thermal WIMP scenario.

hep-ph↗

arXiv2012

Signature of same-sign top pair production mediated by a nonuniversal $Z^\prime$ with QCD next-to-leading accuracy at the LHC

We present a detailed study of the same-sign top pair production mediated by a non-universal $Z^\prime$ including production and decay at the Large Hadron Collider (LHC) at the QCD next-to-leading order (NLO) level, using the narrow width approximation and helicity amplitudes method. We find that the QCD NLO corrections can loose the constraint on the model parameters and reduce the dependence of the total cross sections on the factorization scale significantly. We also study the signature and backgrounds of the process at the NLO level. In order to suppress the backgrounds, we further investigate the difference between the production rates of the positively and negatively charged dilepton at the LHC, and find that the same-sign dilepton signal of the new physics could be discovered more easily.

hep-ph↗

arXiv2012

Type II Seesaw at LHC: the Roadmap

In this Letter we revisit the type-II seesaw mechanism based on the addition of a weak triplet scalar to the standard model. We perform a comprehensive study of its phenomenology at the LHC energies, complete with the electroweak precision constraints. We pay special attention to the doubly-charged component, object of collider searches for a long time, and show how the experimental bound on its mass depends crucially on the particle spectrum of the theory. Our study can be used as a roadmap for future complete LHC studies.

hep-ph↗

arXiv2012

Warm Dark Matter in Low Scale Left-Right Theory

We investigate the viability of having dark matter in the minimal left-right symmetric theory. We find the lightest right-handed neutrino with a mass around keV as the only viable candidate consistent with a TeV scale of left-right symmetry. In order to account for the correct relic density with such low scales, the thermal overproduction of the dark matter in the early universe is compensated by a sufficient late entropy production due to late decay of heavier right-handed neutrinos. We point out that the presence of the right-handed charge-current interactions, operative around the QCD phase transition, has a crucial impact on the amount of dilution, as does the nature of the phase transition itself. A careful numerical study, employing the Boltzmann equations, reveals the existence of a narrow window for the right-handed gauge boson mass, possibly within the reach of LHC (in disagreement with a previous study). We also elaborate on a variety of astrophysical, cosmological and low energy constraints on this scenario.

hep-ph↗

arXiv2011

Perturbative unitarity constraints on general W' models and collider implications

We study perturbative unitarity constraints on general W' models by considering the high energy behavior of fermion scattering into gauge bosons. In most cases we survey, a Z' boson with a comparable mass must be present for the theory to be consistent, with fixed couplings to the standard model gauge bosons and fermions. Applying these results to a class of W' models which explains the top quark forward-backward asymmetry observed at the Tevatron, we find that a Z' must exist with a mass below 7-8 TeV and sizable coupling to the light quarks. While such a Z' is strongly constrained by existing experiments, we show that the LHC can explore the entire mass range up to the unitarity limit. We also show how it is possible, by raising the Z' mass consistent with unitarity, to explain the CDF Wjj excess in terms of a light W', without generating an excess in Zjj events.

hep-ph↗

arXiv2011

Dark Matter as the Trigger of Strong Electroweak Phase Transition

In this Letter, we propose a new possible connection between dark matter relic density and baryon asymmetry of the universe. The portal between standard model sector and dark matter not only controls the relic density and detections of dark matter, but also allows the dark matter to trigger the first order electroweak phase transition. We discuss systematically possible scalar dark matter candidates, starting from a real singlet to arbitrary high representations. We show that the simplest realization is provided by a doublet, and that strong first-order electroweak phase transition implies a lower bound on the dark matter direct detection rate. The mass of dark matter lies between 45 and 80 GeV, allowing for an appreciable invisible decay width of the Standard Model Higgs boson, which is constrained to be lighter than 130 GeV for the sake of the strong phase transition.

hep-ph↗

arXiv2011

Next-to-leading order QCD corrections to $tZ$ associated production via the flavor-changing neutral-current couplings at hadron colliders

We present the complete next-to-leading order (NLO) QCD corrections to $tZ$ associated production induced by the model-independent $tqg$ and $tqZ$ flavor-changing neutral-current couplings at hadron colliders, respectively. Our results show that, for the $tuZ$ coupling the NLO QCD corrections can enhance the total cross sections by about 60% and 42%, and for the $tcZ$ coupling by about 51% and 43% at the Tevatron and LHC, respectively. The NLO corrections, for the $tug$ couplings, can enhance the total cross sections by about 27%, and by about 42% for the $tcg$ coupling at the LHC. We also consider the mixing effects between the $tqg$ and $tqZ$ couplings for this process, which can either be large or small depending on the values of the anomalous couplings. Besides, the NLO corrections reduce the dependence of the total cross sections on the renormalization or factorization scale significantly, which lead to increased confidence on the theoretical predictions. And we also evaluate the NLO corrections to several important kinematic distributions.

hep-ph↗

arXiv2011

Isospin-Violating Dark Matter and Neutrinos From the Sun

We study the indirect detection of dark matter through neutrino flux from their annihilation in the center of the Sun, in a class of theories where the dark matter-nucleon spin-independent interactions break the isospin symmetry. We point out that, while the direct detection bounds with heavy targets like Xenon are weakened and reconciled with the positive signals in DAMA and CoGeNT experiments, the indirect detection using neutrino telescopes can impose a relatively stronger constraint and brings tension to such explanation, if the annihilation is dominated by heavy quark or $τ$-lepton final states. As a consequence, the qualified isospin violating dark matter candidate has to preferably annihilate into light flavors.

hep-ph↗

arXiv2011

Inert Doublet Dark Matter and Mirror/Extra Families after Xenon100

It was shown recently that mirror fermions, naturally present in a number of directions for new physics, seem to require an inert scalar doublet in order to pass the electroweak precision tests. This provides a further motivation for considering the inert doublet as a dark matter candidate. Moreover, the presence of extra families enhances the Standard Model Higgs-nucleon coupling, which has crucial impact on the Higgs and dark matter searches. We study the limits on the inert dark matter mass in view of recent Xenon100 data. We find that the mass of the inert dark matter must lie in a very narrow window 74-76 GeV while the Higgs must weigh more than 400 GeV. For the sake of completeness we discuss the cases with fewer extra families, where the possibility of a light Higgs boson opens up, enlarging the dark matter mass window to m_h/2-76 GeV. We find that Xenon100 constrains the DM-Higgs interaction, which in turn implies a lower bound on the monochromatic gamma-ray flux from DM annihilation in the galactic halo. For the mirror case, the predicted annihilation cross section lies a factor of 4-5 below the current limit set by Fermi LAT, thus providing a promising indirect detection signal.

hep-ph↗

arXiv2011

First Limits on Left-Right Symmetry Scale from LHC Data

We use the early Large Hadron Collider data to set the lower limit on the scale of Left-Right symmetry, by searching for the right-handed charged gauge boson $W_R$ via the final state with two leptons and two jets, for 33/pb integrated luminosity and 7 TeV center-of-mass energy. In the absence of a signal beyond the Standard Model background, we set the bound M_WR > 1.4 TeV at 95% C.L.. This result is obtained for a range of right-handed neutrino masses of the order of few 100 GeV, assuming no accidental cancelation in right-handed lepton mixings.

hep-ph↗

arXiv2011

Effective Angular Momentum Operators in NRQED and Matching at One-Loop Order

We derive the effective angular momentum operator to $1/m^2$ and one-loop order in non-relativistic quantum electrodynamics (NRQED). In both dimensional and three-momentum-cutoff regularization schemes, we obtain the non-relativistic expansion for the spin and orbital angular momentum operators of the electron and photon, respectively. Our result is useful in precision calculations of the angular momentum properties for non-relativistic QED bound states, such as atom systems.

hep-ph↗

arXiv2011

Next-to-leading order QCD corrections to the top quark associated with $γ$ production via model-independent flavor-changing neutral-current couplings at hadron colliders

We present the complete next-to-leading order (NLO) QCD corrections to the top quark associated with $γ$ production induced by model-independent $tqγ$ and $tqg$ flavor-changing neutral-current (FCNC) couplings at hadron colliders, respectively. We also consider the mixing effects between the $tqγ$ and $tqg$ FCNC couplings for this process. Our results show that, for the $tqγ$ couplings, the NLO QCD corrections can enhance the total cross sections by about 50% and 40% at the Tevatron and LHC, respectively. Including the contributions from the $tqγ$, $tqg$ FCNC couplings and their mixing effects, the NLO QCD corrections can enhance the total cross sections by about 50% for the $tuγ$ and $tug$ FCNC couplings, and by about the 80% for the $tcγ$ and $tcg$ FCNC couplings at the LHC, respectively. Moreover, the NLO corrections reduce the dependence of the total cross section on the renormalization and factorization scale significantly. We also evaluate the NLO corrections for several important kinematic distributions.

hep-ph↗