arXiv subjects

Feng Feng

Publications and source records attributed to Feng Feng.

At least 55 records · Page 3Linked to original sources

arXiv2020

Concurrent Crossmodal Feedback Assists Target-searching: Displaying Distance Information Through Visual, Auditory and Haptic Modalities

Humans sense of distance depends on the integration of multi sensory cues. The incoming visual luminance, auditory pitch and tactile vibration could all contribute to the ability of distance judgement. This ability can be enhanced if the multimodal cues are associated in a congruent manner, a phenomenon has been referred to as Crossmodal correspondences. In the context of multi-sensory interaction, whether and how such correspondences influence information processing with continuous motor engagement, particularly for target searching activities, has rarely been investigated. This paper presents an experimental user study to address this question. We built a target-searching application based on a Table-top, displayed the unimodal and Crossmodal distance cues concurrently responding to peoples searching movement, measured task performance through kinematic evaluation. We find that the Crossmodal display an audio display lead to improved searching efficiency and accuracy. More interestingly, this improvement is confirmed by kinematic analysis, which also unveiled the underlying movement features that could account for this improvement. We discussed how these findings could shed lights on the design of assistive technology and of other multi sensory interaction.

cs.HC↗

arXiv2020

Exploring crossmodal perceptual enhancement and integration in a sequence-reproducing task with cognitive priming

Leveraging the perceptual phenomenon of crossmoal correspondence has been shown to facilitate peoples information processing and improves sensorimotor performance. However for goal-oriented interactive tasks, the question of how to enhance the perception of specific Crossmodal information, and how Crossmodal information integration takes place during interaction is still unclear. The present paper reports two experiments investigating these questions. In the first experiment, a cognitive priming technique was introduced as a way to enhance the perception of two Crossmodal stimuli, in two conditions respectively, and their effect on sensory-motor performance was observed. Based on the results, the second experiment combined the two Crossmodal stimuli in the same interfaces in a way that their correspondence congruency was mutually exclusive. The same priming techniques was applied as a manipulating factor to observe the Crossmodal integration process. Results showed that first, the Crossmodal integration during interaction can be enhanced by the priming technique, but the effect varies according to the combination of Crossmodal stimuli and the types of priming material. Moreover, peoples subjective evaluations towards priming types were in contradiction with their objective behavioural data. Second, when two Crossmodal sequences can be perceived simultaneously, results suggested different perceptual weights are possessed by different participants, and the perceptual enhancement effect was observed only on the dominant one, the pitch-elevation. Furthermore, the Crossmodal integration tended to be integrated in a selective manner without priming. These results contribute design implications for multisensory feedback and mindless computing.

cs.HC↗

arXiv2019

Optimized predictions for $W \to B_c + γ$ by combining light-cone and NRQCD approaches

The rare process of $W$ radiative decay into the $B_c$ meson can serve as an interesting play ground for testing two influential perturbative QCD approaches: non-relativistic quantum chromodynamics (NRQCD) and ligh-cone (LC) factorization. Since the $B_c$ meson is a genuine heavy quarkonium which is composed of two different species of heavy quarks, it is natural to employ NRQCD factorization to tackle this exclusive quarkonium production process; on the other hand, since the mass of the $W$ boson is much greater than that of the $B_c$, the collinear factorization is also a viable approach. To fully disentangle the contributions from several distinct scales $M_W$, $m_Q$, $m_Q v$ ($v$ represents the typical velocity of the $c/\bar{b}$ quarks inside $B_c$), and $Λ_{\rm QCD}$, we carry out a joint analysis that combines both light-cone and NRQCD factorization approaches, and compute the order-$α_s$ correction to $W \to B_c+γ$. With the aid of the celebrated Efremov-Radyushkin-Brodsky-Lepage (ERBL) evolution equation, we resum the leading collinear logarithms $α_s \ln\! {M_W\over m_Q}$ to all orders in $α_s$. We also explore some phenomenological implications of our predictions.

hep-ph↗

arXiv2018

Mixed electroweak-QCD corrections to $e^+e^-\to μ^+μ^- H$ at CEPC with finite-width effect

The associated production of Higgs boson with a muon pair, $e^+e^-\to μ^+μ^- H$, is one of the golden channels to pin down the properties of the Higgs boson in the prospective Higgs factories exemplified by \textsf{CEPC}. The projected accuracy of the corresponding cross section measurement is about per cent level at CEPC. In this work, we investigate both ${\mathcal O}(α)$ weak correction and the ${\mathcal O}(αα_s)$ mixed electroweak-QCD corrections for this channel, appropriately taking into account the effect of finite $Z^0$ width. The $μ^+μ^-$ invariant mass spectrum is also predicted. The mixed electroweak-QCD correction turns out to reach 1.5\% of the Born-order result, and thereby must be included in future confrontation with the data. We also observe that, after including higher-order corrections, the simplified prediction for the integrated cross section employing the narrow-width-approximation may deviate from our full result by a few per cents.

hep-ph↗

arXiv2018

Next-to-leading-order QCD corrections to gluon fragmentation into ${}^1S_0^{(1,8)}$ quarkonia

Within the NRQCD factorization framework, we compute the next-to-leading-order QCD corrections to the gluon fragmentation into the ${}^1S_0^{(1,8)}$ Fock components of a quarkonium, at the lowest order in velocity expansion. We follow the operator definition of the fragmentation function advanced by Collins and Soper. The key technique underpinning our calculation is the sector decomposition method widely used in the area of multi-loop computation. It is found that the NLO QCD corrections have significant effects, and qualitatively modify the profiles of the corresponding leading-order fragmentation functions.

hep-ph↗

arXiv2018

Thermodynamics analysis on BaF2 intermediate phase in solution-derived YBCO superconducting film deposition

In the YBa2Cu3O7-δ (YBCO) high temperature superconducting thin film fabrication via the chemical solution deposition method, BaF2 is an important intermediate phase during heat treatment. In this paper, BaF2 thermodynamics stability was analyzed through calculating the standard Gibbs free energy change (ΔGT) of the reactions related to other intermediate phases within the temperature range of 700-1000 K. Two thermodynamics methods, the Gibbs free energy function method and standard formation molar Gibbs free energy method, were utilized to obtain the ΔGT values. The formation priority of BaF2 relative to other intermediate phases were verified at higher temperatures, while the possibility of BaCO3 formation was found at 700 K.

cond-mat.supr-con↗

arXiv2018

Accurate evaluation of the fractal dimension based on a single morphological image

Fractal dimension (D) is an effective parameter to represent the irregularity and fragmental property of a self-affine surface, which is common in physical vapor deposited thin films. D could be evaluated through the scaling performance of surface roughness by using atomic force microscopy (AFM) measurements, but lots of AFM images with different scales (L) are needed. In this study, a surface roughness prediction (SRP) method was proposed to evaluate D values of a single AFM image, in which the roughness at smaller L was estimated by image segmentation with flatten modification. Firstly, a series of artificial fractal surfaces with ideal dimension (Di) values ranging from 2.1 to 2.9 were generated through Weierstrass-Mandelbrot (W-M) function, in order to compare SRP method with traditional methods such as box counting method and power spectral density method. The calculated dimension (Dc) by SRP method was much closer to Di than the other methods, with a mean relative error of only 0.64%. Secondly, SRP method was utilized to deal with real surfaces, which were AFM images of amorphous alumina thin films with L of 1-70 μm. Dc obtained by SRP method based on a single AFM image was also close to the result in our previous study by multi-image analysis at L above 10 μm, while the larger Dc at smaller L was consisted with the actual surface feature. The validity of SRP method and the physics nature of real surfaces were discussed, which might be helpful to obtain more understandings of fractal geometry.

cond-mat.mtrl-sci↗

arXiv2017

Fragmentation function of gluon into spin-singlet $P$-wave quarkonium

Following the operator definition of the fragmentation function developed by Collins and Soper, we compute the gluon-to-$h_c$ fragmentation function at the lowest order in the velocity expansion in NRQCD factorization approach. Utilizing some modern technique developed in the area of multi-loop calculation, we are able to analytically deduce the infrared-finite color-singlet short-distance coefficient associated with the fragmentation function. The fragmentation probability for gluon into $h_c$ is estimated to be order $10^{-6}$.

hep-ph↗

arXiv2017

Next-to-leading-order QCD corrections to $e^+e^-\to H+γ$

The associated production of Higgs boson with a hard photon at lepton collider, i.e., $e^+e^-\to Hγ$, is known to bear a rather small cross section in Standard Model, and can serve as a sensitive probe for the potential new physics signals. Similar to the loop-induced Higgs decay channels $H\to γγ, Zγ$, the $e^+e^-\to Hγ$ process also starts at one-loop order provided that the tiny electron mass is neglected. In this work, we calculate the next-to-leading-order (NLO) QCD corrections to this associated $H+γ$ production process, which mainly stem from the gluonic dressing to the top quark loop. The QCD corrections are found to be rather modest at lower center-of-mass energy range ($\sqrt{s}<300$ GeV), thus of negligible impact on Higgs factory such as CEPC. Nevertheless, when the energy is boosted to the ILC energy range ($\sqrt{s}\approx 400$ GeV), QCD corrections may enhance the leading-order cross section by $20\%$. In any event, the $e^+e^-\to Hγ$ process has a maximal production rate $σ_{\rm max}\approx 0.08$ fb around $\sqrt{s}= 250$ GeV, thus CEPC turns out to be the best place to look for this rare Higgs production process. In the high energy limit, the effect of NLO QCD corrections become completely negligible, which can be simply attributed to the different asymptotic scaling behaviors of the LO and NLO cross sections, where the former exhibits a milder decrement $\propto 1/s$ , but the latter undergoes a much faster decrease $\propto 1/s^2$.

hep-ph↗

arXiv2017

Next-to-next-to-leading-order QCD corrections to hadronic width of pseudoscalar quarkonium

We compute the next-to-next-to-leading order (NNLO) QCD corrections to the hadronic decay rates of the pseudoscalar quarkonia, at the lowest order in velocity expansion. The validity of NRQCD factorization for inclusive quarkonium decay process, for the first time, is verified to relative order $α_s^2$. As a byproduct, the renormalization group equation (RGE) of the leading NRQCD 4-fermion operator ${\cal O}_1({}^1S_0)$ is also deduced to this perturbative order. By incorporating this new piece of correction together with available relativistic corrections, we find that there exists severe tension between the state-of-the-art NRQCD predictions and the measured $η_c$ hadronic width, and in particular the branching fraction of $η_c\to γγ$. NRQCD appears to be capable of accounting for $η_b$ hadronic decay to a satisfactory degree, and our most refined prediction is ${\rm Br}(η_b\to γγ) = (4.8\pm 0.7)\times 10^{-5}$.

hep-ph↗

arXiv2017

Mixed electroweak-QCD corrections to $e^+e^-\to HZ$ at Higgs factory

The prospective Higgs factories, exemplified by ILC, FCC-ee and CEPC, plan to conduct the precision Higgs measurements at the $e^+e^-$ center-of-mass energy around 250 GeV. The cross sections for the dominant Higgs production channel, the Higgsstrahlung process, can be measured to a (sub-) percent accuracy. Merely incorporating the well-known next-to-leading order (NLO) electroweak corrections appears far from sufficient to match the unprecedented experimental precision. In this work, we make an important advancement toward this direction by investigating the mixed electroweak-QCD corrections to $e^+e^-\to HZ$ at next-to-next-to-leading order (NNLO) for both unpolarized and polarized $Z$ boson. The corrections turn out to reach one percent level of the Born-order results, thereby must be incorporated in the future confrontation with the data.

hep-ph↗

arXiv2017

Mining Behavioral Patterns from Millions of Android Users

The prevalence of smart mobile devices has promoted the popularity of mobile applications (a.k.a. apps). Supporting mobility has become a promising trend in software engineering research. This article presents an empirical study of behavioral service profiles collected from millions of users whose devices are deployed with Wandoujia, a leading Android app store service in China. The dataset of Wandoujia service profiles consists of two kinds of user behavioral data from using 0.28 million free Android apps, including (1) app management activities (i.e., downloading, updating, and uninstalling apps) from over 17 million unique users and (2) app network usage from over 6 million unique users. We explore multiple aspects of such behavioral data and present patterns of app usage. Based on the findings as well as derived knowledge, we also suggest some new open opportunities and challenges that can be explored by the research community, including app development, deployment, delivery, revenue, etc.

cs.CY↗

arXiv2016

Critical Current Survival in YBCO Superconducting Layer of the Delaminated Coated Conductor

High temperature superconducting coated conductor (CC) could be practically applied in electric equipment due to its favorable mechanical properties and the critical current performance of YBCO superconducting layer. It is well known that CC could be easily delaminated because of its poor stress tolerance in thickness direction, i.e. along the c-axis of YBCO. Commonly, a stack including YBCO layer and silver stabilizer could be obtained after the delamination. It would be interesting to investigate the superconducting properties of the delaminated stack, since it could also be considered as a new type of CC with the silver stabilizer as the buffer layer, which is quite different from the oxide buffer layers in the traditional CC and might lead to new applications. In this study, a CC sample was delaminated by liquid nitrogen immersing. A Hall probe scanning system was employed to measure the critical current (IC) distribution of the original sample and the obtained stack. It was found that IC could be partially preserved after the delamination. Dense and crack-free morphologies of the delaminated surfaces were observed by scanning electron microscopy, and the potential application of the obtained stack in superconducting joint technology was discussed.

cond-mat.supr-con↗

arXiv2015

Next-to-next-to-leading-order QCD corrections to $χ_{c0,2}\rightarrow γγ$

We calculate the next-to-next-to-leading-order (NNLO) perturbative corrections to $P$-wave quarkonia annihilation decay to two photons, in the framework of nonrelativistic QCD (NRQCD) factorization. The order-$α_s^2$ short-distance coefficients associated with each helicity amplitude are presented in a semi-analytic form, including the "light-by-light" contributions. With substantial NNLO corrections, we find disquieting discrepancy when confronting our state-of-the-art predictions with the latest \textsf{BESIII} measurements, especially fail to account for the measured $χ_{c2}\toγγ$ width. Incorporating the effects of spin-dependent forces would even exacerbate the situation, since it lifts the degeneracy between the nonperturbative NRQCD matrix elements of $χ_{c0}$ and $χ_{c2}$ toward the wrong direction. We also present the order-$α_s^2$ predictions to $χ_{b0,2}\toγγ$, which await the future experimental test.

hep-ph↗

arXiv2015

Can NRQCD explain the $γγ^* \to η_c$ transition form factor data?

Unlike the bewildering situation in the $γγ^*\to π$ form factor, a widespread view is that perturbative QCD can decently account for the recent \textsc{BaBar} measurement of $γγ^*\to η_c$ transition form factor. The next-to-next-to-leading order (NNLO) perturbative correction to the $γγ^*\to η_{c,b}$ form factor, is investigated in the NRQCD factorization framework for the first time. As a byproduct, we obtain by far the most precise order-$α_s^2$ NRQCD matching coefficient for the $η_{c,b}\to γγ$ process. After including the substantial negative order-$α_s^2$ correction, the good agreement between NRQCD prediction and the measured $γγ^*\to η_c$ form factor is completely ruined over a wide range of momentum transfer squared. This eminent discrepancy casts some doubts on the applicability of NRQCD approach to hard exclusive reactions involving charmonium.

hep-ph↗

arXiv2015

Relativistic corrections to $Υ$ exclusive decay into double $S-$wave charmonia

Within the framework of nonrelativisitic QCD factorization formalism, we present the next-to-leading-order relativistic corrections to $Υ$ exclusive decay into $η_c$ plus $J/ψ$. The double charmonia can be produced through several immediate channels, i.e. $Υ\to g^*g^*g^*\to η_c+J/ψ$, $Υ\to g^*g^*γ^*\to η_c+J/ψ$, and $Υ\to γ^*\to η_c+J/ψ$. The amplitudes of these three channels are obtained accurate up to ${\cal O}(α_s^3 v^2)$, ${\cal O}(αα_s^2 v^2)$, and ${\cal O}(αα_s^2 v^2)$ respectively, where $v$ indicates the typical heavy quark velocity in bottomonium and/or charmonium rest frame. The decay rates are also presented. We find the next-to-leading-order relativistic corrections to the short distance coefficients as well as the decay rates are both significant and negative, especially for the corrections from bottomonium. More seriously, the decay rates are even brought into negative by including the relativistic corrections, which indicates the poor convergence for the velocity expansion in this kind of processes. Detailed analysis is given in the paper.

hep-ph↗

arXiv2014

Short-range force between two Higgs bosons

The $S$-wave scattering length and the effective range of the Higgs boson in Standard Model are studied using effective-field-theory approach. After incorporating the first-order electroweak correction, the short-range force between two Higgs bosons remains weakly attractive for $M_H=126$ GeV. It is interesting to find that the force range is about two order-of-magnitude larger than the Compton wavelength of the Higgs boson, almost comparable with the typical length scale of the strong interaction.

hep-ph↗

arXiv2013

A Low-Fluorine Solution with the F/Ba Mole Ratio of 2 for the Fabrication of YBCO Films

In the reported low-fluorine MOD-YBCO studies, the lowest F/Ba mole ratio of the precursor solution was 4.5. However, further lowering the F/Ba ratio is important according to the researches of YBCO thick film. On the other hand, the F/Ba ratio is necessary to be at least 2 for the full conversion of the Ba precursor to BaF_2 to avoid the formation of BaCO_3, which is detrimental to the superconducting performance. In this study, a novel solution with the F/Ba mole ratio of 2 was developed, in which the fluorine content was only about 10.3% of that used in the conventional TFA-MOD method. Attenuated total reflectance-Fourier transformed-infrared spectra(ATR-FT-IR) revealed that BaCO_3 was remarkably suppressed in the as-pyrolyzed film and eliminated at 700 Celsius degree. Thus YBCO films with a critical current density (J_c) over 5 MA cm^{-2} (77 K, 0 T, 200 nm thickness) could be obtained on LAO single crystal substrates. In-situ FT-IR spectra showed that no obvious fluorinated gaseous by-products were detected in the pyrolysis step, which indicated that all of the F atoms might remain in the film as fluorides. X-ray diffraction (XRD) θ/2θ-scan showed that BaF_2, but neither YF_3 nor CuF_2, was detected in the films quenched at 400 - 800 Celsius degree. The formation priority of BaF_2 over YF_3 and CuF_2 was interpreted by the chemical equilibrium of the potential reactions. Our study could enlarge the synthesis window of the precursor solution for MOD-YBCO fabrication and open a gate to study the fluorine content in the precursor solution continuously and systematically.

cond-mat.mtrl-sci↗