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1. chinaXiv:201712.00399 [pdf]

Spatio-temporal variations of soil water content and salinity around individual Tamarix ramosissima in a semi-arid saline region of the upper Yellow River, Northwest China

YANG Benman; WANG Ruoshui; XIAO Huijie; CAO Qiqi; LIU Tao
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science

Ecological restoration by Tamarix plants on semi-arid saline lands affects the accumulation, distribution patterns and related mechanisms of soil water content and salinity. In this study, spatio-temporal variations of soil water content and salinity around natural individual Tamarix ramosissima Ledeb. were investigated in a semi-arid saline region of the upper Yellow River, Northwest China. Specifically, soil water content, electrical conductivity (ECe), sodium adsorption ratio (SARe), and salt ions (including Na+, K+, Ca2+, Mg2+ and SO42–) were measured at different soil depths and at different distances from the trunk of T. ramosissima in May, July, and September 2016. The soil water content at the 20–80 cm depth was significantly lower in July and September than in May, indicating that T. ramosissima plants absorb a large amount of water through the roots during the growing period, leading to the decreasing of soil water content in the deep soil layer. At the 0–20 cm depth, there was a salt island effect around individual T. ramosissima, and the ECe differed significantly inside and outside the canopy of T. ramosissima in May and July. Salt bioaccumulation and stemflow were two major contributing factors to this difference. The SARe at the 0–20 cm depth was significantly different inside and outside the canopy of T. ramosissima in the three sampling months. The values of SARe at the 60–80 cm depth in May and July were significantly higher than those at the 0–60 cm depth and higher than that at the corresponding depth in September. The distribution of Na+ in the soil was similar to that of the SARe, while the concentrations of K+, Ca2+, and Mg2+ showed significant differences among the sampling months and soil depths. Both season and soil depth had highly significant effects on soil water content, ECe and SARe, whereas distance from the trunk of T. ramosissima only significantly affected ECe. Based on these results, we recommend co-planting of shallow-rooted salt-tolerant species near the Tamarix plants and avoiding planting herbaceous plants inside the canopy of T. ramosissima for afforestation in this semi-arid saline region. The results of this study may provide a reference for appropriate restoration in the semi-arid saline regions of the upper Yellow River.

submitted time 2017-12-08 From cooperative journals:《Journal of Arid Land》 Hits10087Downloads1272 Comment 0

2. chinaXiv:201606.00349 [pdf]

Electroweak Beautygenesis: From b -> s CP Violation to the Cosmic Baryon Asymmetry

Liu, Tao; Ramsey-Musolf, Michael J.; Shu, Jing
Subjects: Physics >> The Physics of Elementary Particles and Fields

We address the possibility that CP violation in B-s-(B) over bar (s) mixing may help explain the origin of the cosmic baryon asymmetry. We propose a new baryogenesis mechanism-"electroweak beautygenesis"-explicitly showing that these two CP-violating phenomena can be sourced by a common CP phase. As an illustration, we work in the two-Higgs-doublet model. Because the relevant CP phase is flavor off diagonal, this mechanism is less severely constrained by null results of electric dipole moment searches than other scenarios. We show how measurements of flavor observables by the D0, CDF, and LHCb collaborations test this scenario.

submitted time 2016-06-30 Hits1327Downloads615 Comment 0

3. chinaXiv:201606.00311 [pdf]

Cancellations Between Two-Loop Contributions to the Electron Electric Dipole Moment with a CP-Violating Higgs Sector

Bian, Ligong; Liu, Tao; Shu, Jing
Subjects: Physics >> The Physics of Elementary Particles and Fields

We present a class of cancellation conditions for suppressing the total contributions of Barr-Zee diagrams to the electron electric dipole moment (eEDM). Such a cancellation is of particular significance after the new eEDM upper limit was released by the ACME Collaboration, which strongly constrains the allowed magnitude of CP violation in Higgs couplings and hence the feasibility of electroweak baryogenesis (EWBG). Explicitly, if both the CP-odd Higgs-photon-photon (Z boson) and the CP-odd Higgs-electron-positron couplings are turned on, a cancellation may occur either between the contributions of a CP-mixing Higgs boson, with the other Higgs bosons being decoupled, or between the contributions of CP-even and CP-odd Higgs bosons. With a cancellation, large CP violation in the Higgs sector is still allowed, yielding successful EWBG. The reopened parameter regions would be probed by future neutron, mercury EDM measurements, and direct measurements of Higgs CP properties at the Large Hadron Collider Run II and future colliders.

submitted time 2016-06-24 Hits1309Downloads664 Comment 0

4. chinaXiv:201605.01716 [pdf]

Di-photon Higgs signal at the LHC: A comparative study in different supersymmetric models

Cao, Junjie; Heng, Zhaoxia; Liu, Tao; Yang, Jin Min
Subjects: Physics >> The Physics of Elementary Particles and Fields

As the most important discovery channel for a light Higgs boson at the LHC the di-photon signal gg --> h --> gamma gamma is sensitive to underlying physics. In this work we investigate such a signal in a comparative way by considering three different supersymmetric models, namely the minimal supersymmetric standard model (MSSM), the next-to-minimal supersymmetric standard model (NMSSM) and the nearly minimal supersymmetric standard model (nMSSM). Under the current collider and cosmological constraints we scan over the parameter space and obtain the following observation in the allowed parameter space: (i) In the nMSSM the signal rate is always suppressed; (ii) In the MSSM the signal rate is suppressed in most cases, but in a tiny corner of the parameter space it can be enhanced (maximally by a factor of 2); (iii) In the NMSSM the signal rate can be enhanced or suppressed depending on the parameter space, and the enhancement factor can be as large as 7. (C) 2011 Elsevier B.V. All rights reserved.

submitted time 2016-05-14 Hits1489Downloads797 Comment 0

5. chinaXiv:201605.01708 [pdf]

Heavy standard model-like Higgs boson and a light stop from Yukawa-deflected gauge mediation

Kang, Zhaofeng; Li, Tianjun; Liu, Tao; Tong, Chunli; Yang, Jin Min
Subjects: Physics >> The Physics of Elementary Particles and Fields

To obtain a standard model-like Higgs boson around 125 GeV in the minimal supersymmetric standard model with minimal gauge mediation of supersymmetry breaking (GMSB), a heavy stop at multi-TeV level is needed and incurs severe fine-tuning, which can be ameliorated in the framework of the deformed GMSB with visible-hidden direct Yukawa interactions (YGMSB). We examine some general features of the YGMSB and focus on the scenario with Higgs-messenger couplings (HYGMSB) which can automatically maintain the minimal flavor violation. It turns out that such a Yukawa mediation scenario can give a large -Lambda(t) and -m((t) over tildeL,R)(2), leading to a maximal stop mixing, and thus can readily give a light stop ((t) over tilde (1)) below the TeV scale. However, we find that in the minimal HYGMSB scenario, m(Hu)(2) is too large and then the electroweak symmetry breaking is inconsistent with the large stop mixing. To solve this problem, we modify the hidden sectors in two ways, adding a new strong gauge dynamics or introducing the (10, (10) over bar) messengers. For each case we present some numerical studies.

submitted time 2016-05-14 Hits1178Downloads720 Comment 0

6. chinaXiv:201605.01145 [pdf]

Pseudo-goldstino and electroweakinos via VBF processes at LHC

Liu, Tao; Wang, Lin; Yang, Jin Min
Subjects: Physics >> The Physics of Elementary Particles and Fields

The multi-sector SUSY breaking predicts pseudo-goldstino which can couple to the visible sector more strongly than the ordinary gravitino and thus induce the decays of the lightest neutralino and chargino (collectively called electroweakinos) inside the detector. In this note we study the electroweakino pair productions via VBF processes followed by decays to pseudo-goldstino at the LHC. Our Monte Carlo simulations show that at the 14TeV LHC with 3000 fb(-1) luminosity the dominant production channel pp ->chi(+/-)(1)chi(0)(1)jj can have a statistical significance above 2 sigma while other production channels are not accessible.

submitted time 2016-05-09 Hits785Downloads405 Comment 0

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