Search

Abstract The Higgs boson pair production at the LHC provides a probe to the Higgs boson self-coupling. The higher-order QCD corrections in this process are sizable and must be taken into account in comparison with data. Due to the small cross section, it is necessary to consider at least one of the Higgs bosons decaying to bottom quarks. The QCD corrections to the decay processes would also be important in such cases. We present a full calculation of the total and differential cross sections for the b b ¯ γγ $$ b\overline{b}\gamma \gamma $$ final state with next-to-leading order (NLO) QCD corrections. After applying typical kinematic cuts in the final state, we find that QCD NLO corrections in the decay decrease the LO result by 19% and reduce the scale uncertainties by a factor of two. The QCD corrections to the invariant mass m jjγγ distribution, the transverse momentum spectra of the leading bottom quark jet and photon are significant and can not be approximated by a constant factor.

Fostering students’ critical thinking (CT) is an increasing concern in EFL classrooms in China as many students struggle to utilize the skill, particularly in EFL reading comprehension classes. This study investigated the effects of graphic organizers (GOs) on 60 Chinese senior high school students’ CT skills (analyzing and generalizing) in EFL reading classes. This study adopted a quasi-experimental mixed-method research design involving an experiment and an interview. The findings of this study showed the positive impacts of GOs on students’ CT skills. After the intervention, the results of the experimental group improved significantly. The findings showed that GOs could effectively improve the analytical and generalization skills of Chinese high school English reading class students. The students in the experimental group reported that the instructions received were motivating, increased their comprehension, made them more focused on reading and aware of CT skills and how to apply them in real reading contexts. This study implies that teachers may consider GOs an alternative teaching tool to improve CT skills in English Language reading classes, particularly in EFL contexts. Guidelines for teachers to use the different types of GOs to promote critical thinking should also be prepared to ensure the effective use of GOs in promoting reading comprehension and critical thinking skills.

Abstract We consider, at order α s 2 $$ {\alpha}_s^2 $$ in the QCD coupling, top-quark pair production in the continuum at various center-of-mass energies and b-quark pair production at the Z resonance by (un)polarized electron and positron beams. For top quarks we compute the forward-backward asymmetry with respect to the top-quark direction of flight, the associated polar angle distribution, and we analyze the effect of beam polarization on the QCD corrections to the leading-order asymmetry. We calculate also the polarized forward-backward asymmetry. For b-quark production at the Z peak we explore different definitions of A FB. In particular, we analyze b jets defined by the Durham and the flavor-k T clustering algorithms. We compute the inclusive b-jet and two-jet asymmetry with respect to the b-jet direction. For the latter asymmetry the QCD corrections to order α s 2 $$ {\alpha}_s^2 $$ are small. That predestines it to act as a precision observable.

Abstract We study the relations between low-energy constants in the chiral Lagrangians with $$\Delta (1232)$$ Δ ( 1232 ) and those in the quark-level description model up to the third chiral order. Ten structure correspondences are involved in getting the relations. This situation is more complicated than the spin-1/2 baryon case. The obtained results may help to further investigations involving the $$\Delta (1232)$$ Δ ( 1232 ) baryons.

The results of ellipse fitting can be considerably distorted by outliers in the fitted point set.To tackle this problem, three improved ellipse fitting algorithms, one of which is based on least trimmed square, and the other two on dual point removal, are proposed.The least trimmed square algorithm starts from a random sample of the original complete fitted set, and then in each iteration, new fitted set is formed by points with the least residual errors, till the process converges to an ellipse fitting a subset whose members are mostly non-outliers.Dual point removal algorithms, on the other hand, starts from the whole fitted set, removes the two points respectively with the maximal positive and the minimal negative residual errors, and halts when the number of points in the remaining set does not exceeds a user-defined threshold.The two proposed algorithms and existing methods are compared on an image base of actual accessories.Experimental results show that when the number of reserved ellipse points is relatively small, the dual removal-based algorithms present the best fitting accuracies, but are slower than the least trimmed square fitting algorithm.When the best performance with parameter tuning is concerned, however, the least trimmed square algorithm achieves a shape-location matching accuracy of 0.62 pixels and an orientation matching accuracy of 0.6°, at an average execution time of 6.5ms, outperforming other algorithms.Other advantages of the proposed algorithms include the small number of algorithm parameters, the intuitiveness of the parameters, and the insensitivity of the algorithm performance to the parameters.These experimental results provide solid evidences for the effectiveness of the proposed algorithms, especially the least trimmed square algorithm.

The production mechanism of multiquark exotic hadrons in high energy multiproduction processes lies in the structure of the relevant exotic hadrons as well as in some important aspects of high energy scattering, such as multi-parton interactions, underlying events, etc. At mass pole around 2900 MeV, a family of open charm tetraquarks, Tcss and Tcs¯s, are observed in B decay. They are also suitable for study in multiproduction processes to obtain more information on their structure. If these resonances are produced as compact four-quark states, one can predict the production properties based on the similarities in their production mechanism to those of Ξc, Σc, and Λc. Physics implies that the colour and baryon number fluctuations of the preconfinement system in high energy scattering can enhance both the baryon and four-quark state production rates via ‘diquark fragmentation’. We calculate the production properties of the tetraquark family Tcss and Tcs¯s at LHC energy for the forthcoming LHC measurements.

An ongoing outbreak of severe respiratory pneumonia associated with the 2019 novel coronavirus has recently emerged in China. Here we report the epidemiological, clinical, laboratory and radiological characteristics of 19 suspect cases. We compared the positive ratio of 2019-nCoV nucleic acid amplification test results from different samples including oropharyngeal swab, blood, urine and stool with 3 different fluorescent RT-PCR kits. Nine out of the 19 patients had 2019-nCoV infection detected using oropharyngeal swab samples, and the virus nucleic acid was also detected in eight of these nine patients using stool samples. None of positive results was identified in the blood and urine samples. These three different kits got the same result for each sample and the positive ratio of nucleic acid detection for 2019-nCoV was only 47.4% in the suspect patients. Therefore, it is possible that infected patients have been missed by using nucleic acid detection only. It might be better to make a diagnosis combining the computed tomography scans and nucleic acid detection. Keywords: 2019 Novel coronavirus pneumonia, Clinical diagnosis, Nucleic acid amplification test

The heavy singlet Majorana neutrinos are introduced to generate the neutrino mass in the so-called phenomenological type-I seesaw mechanism. The phenomena induced by the heavy Majorana neutrinos are important to search for new physics. In this paper, we explore the heavy Majorana neutrino production and decay at future e−p colliders. The corresponding cross sections via W and photon fusion are predicted for different collider energies. Combined with the results of the heavy Majorana neutrino production via single W exchange, this work can provide helpful information to search for heavy Majorana neutrinos at future e−p colliders. Keywords: Type-I seesaw, Majorana neutrino, e−p collision

C16H14O5, monoclinic, P21/c (no. 14), a = 9.0005(11) Å, b = 16.0386(15) Å, c = 9.8434(11) Å, β = 114.861(14)°, V = 1289.3(3) Å3, Z = 4, Rgt(F) = 0.0458, wRref(F2) = 0.1245, T = 150(1) K.

The Higgs-top coupling plays a central role in the hierarchy problem and the vacuum stability of the Standard Model (SM). We propose a central-edge asymmetry (ACE) to probe the CP violating Higgs-top coupling in dileptonic channel of tt¯h(→bb¯) production at the LHC. We demonstrate that the CP-violating Higgs-top coupling can affect the central-edge asymmetry through distorting Δyℓ+ℓ− distribution because of the contribution of new top charge asymmetric term. Since Δyℓ+ℓ− distribution is frame-independent and has a good discrimination even in boosted regime, we use the jet substructure technique to enhance the observability of the dileptonic channel of tt¯h production. We find that (1) the significance of dileptonic channel of tt¯h production can reach 5σ for CP phase ξ=0,π/4,π/2 when the luminosity L=795,993,1276fb−1 at 14 TeV LHC. (2) the central-edge asymmetry ACE show a good discrimination power of CP phase of tt¯h interaction, which are −40.26%, −26.60%, −9.47% for ξ=0, π/4, π/2 respectively and are hardly affected by the event selections. Besides, by performing the binned-χ2 analysis of Δyℓ+ℓ− distribution, we find that the scalar and pseudo-scalar interactions can be distinguished at 95% C.L. level at 14 TeV HL-LHC.

Abstract The Principle of Maximum Conformality (PMC) provides a systematic way to eliminate the renormalization scheme and renormalization scale uncertainties for high-energy processes. We have observed that by applying PMC scale setting, one obtains comprehensive and self-consistent pQCD predictions for the top-quark pair total cross section and the top-quark pair forward–backward asymmetry in agreement with the measurements at the Tevatron and LHC. As a step forward, in the present paper, we determine the top-quark pole mass via a detailed comparison of the top-quark pair cross section with the measurements at the Tevatron and LHC. The results for the top-quark pole mass are $$m_t=174.6^{+3.1}_{-3.2}$$ mt=174.6-3.2+3.1 GeV for the Tevatron with $$\sqrt{S}=1.96$$ S=1.96 TeV, $$m_t=173.7\pm 1.5$$ mt=173.7±1.5 and $$174.2\pm 1.7$$ 174.2±1.7 GeV for the LHC with $$\sqrt{S} = 7$$ S=7 and 8 TeV, respectively. Those predictions agree with the average, $$173.34\pm 0.76$$ 173.34±0.76 GeV, obtained from various collaborations via direct measurements. The consistency of the pQCD predictions using the PMC with all of the collider measurements at different energies provides an important verification of QCD.