Ning Liu

Ning Liu
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Ning Liu
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High Energy Physics - Phenomenology (27)
 
High Energy Physics - Experiment (13)
 
Physics - Materials Science (9)
 
Physics - Chemical Physics (3)
 
Physics - Mesoscopic Systems and Quantum Hall Effect (2)
 
Physics - Superconductivity (2)
 
Physics - Disordered Systems and Neural Networks (1)
 
Quantitative Biology - Neurons and Cognition (1)
 
Computer Science - Artificial Intelligence (1)
 
Computer Science - Distributed; Parallel; and Cluster Computing (1)

Publications Authored By Ning Liu

Automatic decision-making approaches, such as reinforcement learning (RL), have been applied to (partially) solve the resource allocation problem adaptively in the cloud computing system. However, a complete cloud resource allocation framework exhibits high dimensions in state and action spaces, which prohibit the usefulness of traditional RL techniques. In addition, high power consumption has become one of the critical concerns in design and control of cloud computing systems, which degrades system reliability and increases cooling cost. Read More

Hybrid plasmonic lasers provide deep subwavelength optical confinement, strongly enhanced light-matter interaction and together with nanoscale footprint promise new applications in optical communication, bio-sensing and photolithography. The subwavelength hybrid plasmonic lasers reported so far often use bottom up grown nanowires, nanorods and nanosquares, making it difficult to integrate these devices into industry-relevant high density plasmonic circuits. Here, we report the first experimental demonstration of AlGaInP based, red-emitting hybrid plasmonic lasers at room temperature using lithography based fabrication processes. Read More

We apply high-energy proton ion-implantation to modify TiO2 nanotubes selectively at their tops. In the proton-implanted region we observe the creation of intrinsic co-catalytic centers for photocatalytic H2-evolution. We find proton implantation to induce specific defects and a characteristic modification of the electronic properties not only in nanotubes but also on anatase single crystal (001) surfaces. Read More

In the present work, a simple strategy is used to thermally oxidize TiN nanopowder (ca. 20 nm) to an anatase phase of a TiO2:Ti3+:N compound. In contrast to the rutile phase of such a compound this photocatalyst provides photocatalytic activity for hydrogen evolution under AM1. Read More

Low-dose nitrogen implantation induces in TiO2 nanotubes a co-catalytic activity for photocatalytic H2-evolution. The use of an ion implantation process leads to a N-implanted zone only at the top part of the tubes. The coupling of this top layer and the underlying non-implanted part of the nanotubes strongly contributes to an efficient carrier separation and thus to a significantly enhanced H2 generation. Read More

We utilise the LHC Run-1 and -2 Higgs data to constrain the CP-violating top-Higgs couplings. In order to satisfy the current full Higgs data sets at $2\sigma$ level, the CP-odd component $C^p_t$ and the CP-even component $C^s_t$ have to be within the ranges $|C^p_t|< 0.37$ and $0. Read More

In the present work we show, how a high pressure hydrogenation of commercial anatase or anatase/rutile powder can create a photocatalyst for hydrogen evolution that is highly effective and stable without the need of any additional co-catalyst. This activation effect can not be observed for rutile. For anatase/rutile mixtures, however, a strong synergistic effect is found (similar to findings commonly observed for noble metal decorated TiO2). Read More

In the present work, extended Argon ion bombardment was used to modify anatase TiO2 nanotube (NTs) layers. In situ X-ray photoelectron spectroscopy revealed a high content of sub-oxide formed (Ti3+, Ti2+ states) in the nanotube layers. These samples were tested for their ability to show open-circuit photocatalytic hydrogen evolution. Read More

Metal-intercalated iron selenides are a class of superconductors that have received much attention but are less understood in comparison with their FeAs-based counterparts. Here, the controversial issues such as Fe vacancy, the real phase responsible for superconductivity, and lattice stability have been addressed based on first-principles calculations. New insights into the distinct features in terms of carrier doping have been revealed. Read More

Inspired by the recent CMS $h \to \mu\tau$ excess, we calculate the lepton flavor violating Higgs decay $h \to \mu\tau$ in the littlest Higgs model with T-parity (LHT). Under the constraints of $\ell_i \to \ell_j \gamma$, $Z \to \ell_i \bar{\ell}_j$ and Higgs data, we find that the branching ratio of $h \to \mu\tau$ can maximally reach $\mathcal O(10^{-4})$. We also investigate the correlation between $h \to \mu\tau $, $\tau \to \mu \gamma$ and $Z \to \mu\tau$, which can be used to test LHT model at future $e^+e^-$ colliders. Read More

In this paper, we study the recent 750 GeV diphoton excess in the Hill Model with vector-like fermions, in which the singlet-like Higgs boson is chosen as 750 GeV resonance and is mainly produced by the gluon fusion through vector-like top and bottom quarks. Meanwhile its diphoton decay rate is greatly enhanced by the vector-like lepton. Under the current experimental and theoretical constraints, we present the viable parameter space that fits the 750 GeV diphoton signal strength at 13 TeV LHC. Read More

Motivated by the search for flavor-changing neutral current (FCNC) top quark decays at the LHC, we calculate rare Higgs three body decay $H\rightarrow Wbc$ induced by top-Higgs FCNC coupling in the littlest Higgs model with T-parity(LHT). We find that the branching ratios of $H\rightarrow Wbc$ in the LHT model can reach $\mathcal O(10^{-7})$ in the allowed parameter space. Read More

In the framework of the minimal $U(1)_{B-L}$ extension of the Standard Model, we investigate the Higgs boson production processes $e^{+}e^{-}\rightarrow ZH$, $e^{+}e^{-}\rightarrow \nu_{e}\bar{\nu_{e}}H$, $e^{+}e^{-}\rightarrow t\bar{t}H$, $e^{+}e^{-}\rightarrow ZHH$ and $e^{+}e^{-}\rightarrow \nu_{e}\bar{\nu_{e}}HH$ at the International Linear Collider (ILC). We present the production cross sections, the relative corrections and compare our results with the expected experimental accuracies for Higgs decay channel $H\rightarrow b\bar{b}$. In the allowed parameter space, we find that the effects of the three single Higgs boson production processes might approach the observable threshold of the ILC, and that the Higgs signal strengths $\mu_{b\bar{b}}$ of the two double Higgs boson production processes are all out of the observable threshold of the ILC so that the effects will be difficult to be observed at the ILC. Read More

Top squark (stop) plays a key role in the radiative stability of the Higgs boson mass in supersymmetry (SUSY). The LHC searches for stop have made a great progress and tightly constrained the stop mass during Run-1. In this work, we use the LHC Run-1 data to determine the lower mass limit of the right-handed stop in a natural SUSY scenario, where the higgsinos $\tilde{\chi}^0_{1,2}$ and $\tilde{\chi}^\pm_{1}$ are light and nearly degenerate. Read More

By using evolutionary algorithm USPEX, we have predicted a number of stable zirconium carbides. In addition to the well-known rocksalt-type stoichiometric ZrC (Fm-3m), present prediction also identifies five stable substoichiometric zirconium carbides adopting rocksalt-type structures with ordered carbon vacancies, Zr8C7 (P-1), Zr6C5 (C2/m), Zr5C4 (P-1), Zr3C2 (C2/m), and Zr2C (Fd-3m). The effects of carbon vacancies on structural and mechanical properties are investigated. Read More

The top partner as a hallmark of the Littlest Higgs model with $T$-parity (LHT model) has been extensively searched for during the Large Hadron Collider (LHC) Run-1. With the increasing mass limits on the top partner, the single production of the top partner will be dominant over the pair production. Under the constraints from the Higgs data, the electroweak precision observables and $R_b$, we find that the mass of $T$-even top partner ($T_+$) has to be heavier than 730 GeV. Read More

In this work, we investigate the one-loop QCD correction to top pair production in the littlest Higgs model with T-parity at the LHC. We calculate the relative correction of the top pair production cross section and top-antitop spin correlation at the LHC for $\sqrt{s}=8,14$ TeV. We find that the relative corrections of top pair production cross section can reach about $-0. Read More

Neuron is the most important building block in our brain, and information processing in individual neuron involves the transformation of input synaptic spike trains into an appropriate output spike train. Hardware implementation of neuron by individual ionic/electronic coupled device is of great importance for enhancing our understanding of the brain and solving sensory processing and complex recognition tasks. Here, we provide a proof-of-principle artificial neuron with multiple presynaptic inputs and one modulatory terminal based on a proton-coupled oxide-based electric-double-layer transistor. Read More

Inspired by the dendritic integration and spiking operation of a biological neuron, flexible oxide-based neuron transistors gated by solid-state electrolyte films are fabricated on flexible plastic substrates for biochemical sensing applications. When a quasi-static dual-gate laterally synergic sensing mode is adopted, the neuron transistor sensor shows a high pH sensitivity of ~105 mV/pH, which is higher than the Nernst limit. Our results demonstrate that single-spike dynamic mode can remarkably improve the pH sensitivity, reduce response/recover time and power consumption. Read More

In the framework of the Left-Right twin Higgs (LRTH) model, we consider the constrains from the latest search for high-mass dilepton resonances at the LHC and find that the heavy neutral boson $Z_H$ is excluded with mass below 2.76 TeV. Under these constrains, we study the Higgs-Gauge coupling production processes $e^{+}e^{-}\rightarrow ZH$, $e^{+}e^{-}\rightarrow \nu_{e}\bar{\nu_{e}}H$ and $e^{+}e^{-}\rightarrow e^{+}e^{-}H$, top quark Yukawa coupling production process $e^{+}e^{-}\rightarrow t\bar{t}H$, Higgs self-couplings production processes $e^{+}e^{-}\rightarrow ZHH$ and $e^{+}e^{-}\rightarrow \nu_{e}\bar{\nu_{e}}HH$ at $e^{+}e^{-}$ colliders. Read More

We attempt to explain the recent ATLAS 3$\sigma$ excess of dilepton events with an invariant mass near $Z$ peak through the gluino-mediated sbottom production in a simplified scenario inspired by the Minimal Supersymmetric Standard Model (MSSM). The additional $Z$ bosons can be produced through the cascade decay chain $\tilde{g} \to b \tilde{b}^{\dagger}_{1} \to b \bar{b} \tilde{\chi}^{0}_{2,3} \to b \bar{b} \tilde{\chi}^{0}_1 Z$, in which $\tilde b_1$ is the right-handed sbottom, $\tilde\chi_1^0$ is the bino-like lightest supersymmetric particle (LSP) and $\tilde\chi_{2,3}^0$ are two nearly degenerate higgsino-like next-to LSPs (NLSPs). Taking into account the constraint from the LHC search for the gluino-mediated sbottom production in the final states with the missing transverse energy and at least three $b$-jets, we find that the ATLAS on-$Z$ excess can only be marginally explained at $2\sigma$ level. Read More

The measurement of Higgs self-coupling is one of the most crucial physics goals at the future colliders. At the LHC, the di-Higgs production is a main way to measure the Higgs trilinear coupling. As a complementary to the di-Higgs production, $t \bar{t} hh$ process may open a new avenue to measure di-Higgs physics at the LHC and a future 100 TeV $pp$ collider or a high energy $e^+e^-$ collider since the extra $t\bar t$ in the final states may efficiently suppress the backgrounds. Read More

In the littlest Higgs model with T-parity (LHT), we study the $t$-channel single top production in association with a Higgs boson at 8 and 14 TeV LHC. We find that the cross section can be enhanced obviously in this model compared to the Standard Model. By performing a simple parton-level simulation through $pp\rightarrow t(\rightarrow \ell^{+}\nu b)h(\rightarrow b\bar{b})j$ at 14 TeV LHC, we find that the observability of the signal is promising in the favorable parameter space. Read More

In the framework of the littlest Higgs model with T-parity(LHT), we investigate the double Higgs production processes $e^{+}e^{-}\rightarrow ZHH$ and $e^{+}e^{-}\rightarrow \nu\bar{\nu}HH$ at high energy $e^{+}e^{-}$ colliders. We calculate the production cross sections and find that the relative correction at the center-of-mass energy $\sqrt{s}=500$ GeV can maximally reach $-30%$ for the process $e^{+}e^{-}\rightarrow ZHH$ and $-16%$ for the process $e^{+}e^{-}\rightarrow \nu\bar{\nu}HH$ in the allowed parameter space, respectively. These large relative corrections can reach the detection range of the future $e^{+}e^{-}$ colliders so that they can be used to test the LHT effect. Read More

Measuring the Higgs-self coupling is one of the most crucial goals of the future colliders, such as the LHC Run-II and the ILC-based photon collider. Since the new physics can affects the di-Higgs production not only from the Higgs self-coupling but also from the top-Higgs coupling, we investigate the di-Higgs production in the presence of the non-standard top-Higgs coupling at the LHC and ILC-based photon collider given the recent Higgs data. Due to the changed interference behaviors of the top quark loops with itself or $W$ boson loops, we find that the cross section of di-Higgs production at the LHC-14 TeV and ILC-500 GeV can be respectively enhanced up to nearly 3 and 2 times the SM predictions within 2$\sigma$ Higgs data allowed parameter region. Read More

Motivated by the recent LHC Higgs data and null results in searches for any new physics, we investigate the Higgs couplings and naturalness in the littlest Higgs model with T-parity. By performing the global fit of the latest Higgs data, electroweak precise observables and $R_{b}$ measurements, we find that the scale $f$ can be excluded up to 600 GeV at $2\sigma$ confidence level. The expected Higgs coupling measurements at the future collider TLEP will improve this lower limit to above 3 TeV. Read More

We investigate indirect constraints on the top partner within the minimal fermionic top partner model. By performing a global fit of the latest Higgs data, $B_s \to \mu^+\mu^-$ measurements and the electroweak precision observables we find that the top partner with the mass up to 830 GeV is excluded at $2\sigma$ level. Our bound on the top partner mass is much stronger than the bounds obtained from the direct searches at the LHC. Read More

Considering the constraints from the flavor physics, precision electroweak measurements, Higgs data and dark matter detections, we scan over the parameter space of the MSSM and calculate the cross section of $e^+e^- \to h \gamma$ in the allowed parameter space. Since the loop-induced gauge couplings $h\gamma\gamma$ and $hZ\gamma$ can simultaneously contribute to the process $e^+e^- \to h \gamma$, we find the cross section can be sizably enhanced by a light stau, maximally 1.47(1. Read More

In this work, we investigate the Higgs-boson production processes $e^{+}e^{-}\rightarrow ZH$, $e^{+}e^{-}\rightarrow \nu_{e}\bar{\nu_{e}}H$ and $e^{+}e^{-}\rightarrow e^{+}e^{-}H$ in the littlest Higgs model with T-parity. We present the production cross sections, the relative corrections and some distributions of the final states. In the allowed parameter space, we find that the relative corrections of the three production channels are negative, the relative correction of the $ZH$ production can reach $-7. Read More

Motivated by the future precision test of the Higgs boson at an $e^+e^-$ Higgs factory, we calculate the production $e^+e^- \to ZH\gamma$ in the Standard Model with complete next-to-leading order electroweak corrections. We find that for $\sqrt{s}=240$ (350) GeV the cross section of this production is sizably reduced by the electroweak corrections, which is $1.03$ (5. Read More

Since the precise study of Higgs gauge couplings is important to test the Standard Model (SM), we calculate the complete next-to-leading order QCD(NLO QCD) correction to the $pp \to HZW^{\pm}$ production in the SM at 14 TeV LHC. Our results show that the NLO QCD correction can enhance the leading-order cross section of $pp \to HZW^{\pm}$ by 45%, when $ m_H $ = 125.3 GeV. Read More

We investigate a strategy to search for light, nearly degenerate higgsinos within the natural MSSM at the LHC. We demonstrate that the higgsino mass range $\mu$ in $100-150$ GeV, which is preferred by the naturalness, can be probed at $2\sigma$ significance through the monojet search at 14 TeV HL-LHC with 3000 fb$^{-1}$ luminosity. The proposed method can also probe certain region in the parameter space for the lightest neutralino with a high higgsino purity, that cannot be reached by planned direct detection experiments at XENON-1T(2017). Read More

Motivated by the current observation of a 125 GeV Higgs boson, we calculate $t\rightarrow cH$ and $t\rightarrow cg(\gamma)H$ in the unitary gauge in the littlest Higgs model with T-parity(LHT). Due to the large contribution from the new mirror fermions, we find that the branching ratios of $t\rightarrow cH$ and $t\rightarrow cgH$ can be greatly enhanced in the LHT model and maximally reach $\mathcal O(10^{-5})$ in the allowed parameter space. When the mirror fermion mass $M_3 > 2(1. Read More

This paper investigates the impact of electrode geometry on the performance of polymer solar cells (PSCs). Four types of negative electrodes with equal area (0.09 cm2) but different shape (round, oval, square, and triangular) are evaluated with respect to short-circuit current density, open-circuit voltage, fill factor, and power conversion efficiency of PSCs. Read More

Through partial substitution of Sm by U in SmFeAsO, a different member of the family of iron-based superconductors was successfully synthesized. X-ray diffraction measurements show that the lattice constants along the a and c axes are both squeezed through U doping, indicating a successful substitution of U at the Sm site. The parent compound shows a strong resistivity anomaly near 150 K, associated with spin-density-wave instability. Read More

The excess of top quark forward-backward asymmetry ($A^t_{FB}$) reported by the Tevatron and the enhancement of the Higgs decay to diphoton observed by the LHC may point to a same origin of new physics. In this note we examined such anomalies in the two-Higgs-doublet model with a color-triplet scalar. We found that under current experimental constraints this model can simultaneously explain both anomalies at $1\sigma$ level. Read More

In this work, we systematically investigate the one-loop corrections to $t\bar{t}$ production in the littlest Higgs model with T-parity (LHT) at the LHC for $\sqrt{s}=8,14$ TeV. We focus on the effects of LHT particles on $t\bar{t}$ cross section, polarization asymmetries, spin correlation and charge asymmetry at the LHC. We also study the top quark forward-backward asymmetry at Tevatron and its correlations with the LHC observables. Read More

Inspired by the recent LHC Higgs data and null search results of supersymmetry (SUSY), we scan the parameter space of the Minimal Supersymmetric Standard Model (MSSM) with relatively heavy sparticles (1-3 TeV). Then in the parameter space allowed by current collider experiments and dark matter detections, we calculate the complete one-loop SUSY QCD corrections to $pp\to b\bar{b}h$ at the LHC with $\sqrt{s}=14$ TeV and obtain the following observations: (i) For the large values of $\tan\beta$ and low values of $m_{A}$, the SUSY QCD effects can be quite large, which, however, have been excluded by the latest results of LHC search for $H/A \to \tau^{+}\tau^{-}$; (ii) For modest values of $\tan\beta$ and $m_{A}$ which so far survived all experimental constraints, the SUSY QCD corrections can maximally reach about -9%. Read More

In a topcolor-assisted technicolor model (TC2) with large FCNC top quark couplings, we study its correlated contributions to the top quark forward-backward asymmetry ($A_{FB}$) at the Tevatron, the top charge asymmetry ($A_{C}$) and the triple-top production at the LHC. Under current constraints on the top quark from the LHC and Tevatron(such as the total and differential production rates), we scan the parameter space of such a TC2 model. We find that in the allowed parameter space the TC2 model can explain the Tevatron measured $A_{FB}$ at $2\sigma$ level, but meanwhile significantly enhance $A_{C}$ at the LHC. Read More

A precise calculation of the top quark pair production associated with a hard photon is essential for testing the electroweak property of the top quark in the Standard Model (SM). We investigate the one-loop QCD corrections to the process $e^{+}e^{-} \to t\bar{t}\gamma$ at the International Linear Collider (ILC), and find that the $K$-factor can be as large as 1.238 (1. Read More

Thin Co-Mn-Sb films of different compositions were investigated and utilized as electrodes in alumina based magnetic tunnel junctions with CoFe counter electrode. The preparation conditions were optimized with respect to magnetic and structural properties. The Co-Mn-Sb/Al-O interface was analyzed by X-ray absorption spectroscopy and magnetic circular dichroism with particular focus on the element-specific magnetic moments. Read More

A new magnetic logic overcomes the major limitations of field programmable gate arrays while having a 50% smaller unit cell than conventional designs utilizing magnetic tunnel junctions with one Heusler alloy electrode. These show positive and negative TMR values at different bias voltages at room temperature which generally adds an additional degree of freedom to all spintronic devices. Read More

We consider a finite ferroelectric superlattice in which the elementary unit cell is made up of l atomic layers of type A and n atomic layers of type B. Based on the transverse Ising model we examine the phase transition properties of the ferroelectric superlattice. Using the transfer matrix method we derive the equation for the Curie temperature of the superlattice. Read More