Effective Field Theory Techniques Applied to the Properties of the Axion

We utilize the effective field theory approach to study the properties of the axion. In particular, with s as well as u and d quarks regarded to be relatively light we derive a formula for the mass of the axion; a rough estimate of the rate for its dominant decay mode at low energy is also carried out.

Post-Newtonian binary dynamics in the effective field theory of Horndeskigravity

General relativity has been very successful since its proposal more than a century ago.However,various cosmological observations and theoretical consistency still motivate us to explore extended gravity theories.Horndeski gravity stands out as one attractive theory by introducing only one scalar field.Here we formulate the post-Newtonian effective field theory of Horndeski gravity and investigate the conservative dynamics of inspiral compact binary systems.We calculate the leading effective Lagrangian for a compact binary and obtain the periastron advance per period.In particular,we apply our analytical calculation to two binary systems,PSR B 1534+12 and PSR J0737-3039,and constrain the relevant model parameters.This theoretical framework can also be systematically extended to higherorders.

Standard model effective field theory from on-shell amplitudes

We present a general method of constructing unfactorizable on-shell amplitudes(amplitude basis) and build up their one-to-one correspondence to the independent and complete operator basis in effective field theory(EFT).We apply our method to the Standard Model EFT and identify the amplitude basis in dimensions 5 and 6,which correspond to the Weinberg operator and operators in the Warsaw basis,except for some linear combinations.

Renormalization of one-pion exchange in higher partial waves in chiral effective field theory for antinucleon-nucleon system

The renormalization of the iterated onepion exchange(OPE)has been studied in chiral effective field theory(χEFT)for the antinucleon-nucleon(NN)scattering in some partial waves(Phys.Rev.C 105,054005(2022)).In this paper,we go further for the other higher partial waves but with total angular momenta J≤3.Contact interactions are represented by a complex spherical well in the coordinate space.Changing the radius of the spherical well means changing the cutoff.We check the cutoff dependence of the phase shifts,inelasticities,and mixing angles for the partial waves and show that contact interactions are needed at leading order in channels where the singular tensor potentials of OPE are attractive.The results are compared with the energy-dependent partial-wave analysis of NN scattering data.Comparisons between our conclusions and applications of χEFT to the nucleon-nuc-leon system are also discussed.

Strangeness S=-2 baryon-baryon interactions and femtoscopic correlation functions in covariant chiral effective field theory

We study the baryon-baryon interactions with strangeness S=-2 and corresponding momentum correlation functions in leading order covariant chiral effective field theory.The relevant low energy constants are determined by fitting to the latest HAL QCD simulations,taking into account all the coupled channels.Extrapolating the so-obtained strong interactions to the physical point and considering both quantum statistical effects and the Coulomb interaction,we calculate the ΛΛ and Ξ^(-)p correlation functions with a spherical Gaussian source and compare them with recent experimental data.We find a good agreement between our predictions and the experimental measurements by using the source radius determined in proton-proton correlations,which demonstrates the consistency between theory,experiment,and lattice QCD simulations.Moreover,we predict the Σ^(+)Σ^(+),Σ^(+)Λ,and Σ^(+)Σ^(-) interactions and corresponding momentum correlation functions.We further investigate the influence of the source shape and size of the hadron pair on the correlation functions studied and show that the current data are not very sensitive to the source shape.Future experimental measurements of the predicted momentum correlation functions will provide a non-trivial test of not only SU(3) flavor symmetry and its breaking but also the baryon-baryon interactions derived in covariant chiral effective field theory.

Oscillation of Dzyaloshinskii–Moriya interaction driven by weak electric fields

Dzyaloshinskii–Moriya interaction(DMI) is under extensive investigation considering its crucial status in chiral magnetic orders, such as Néel-type domain wall(DW) and skyrmions. It has been reported that the interfacial DMI originating from Rashba spin–orbit coupling(SOC) can be linearly tuned with strong external electric fields. In this work, we experimentally demonstrate that the strength of DMI exhibits rapid fluctuations, ranging from 10% to 30% of its original value, as a function of applied electric fields in Pt/Co/MgO heterostructures within the small field regime(< 10-2V/nm). Brillouin light scattering(BLS) experiments have been performed to measure DMI, and first-principles calculations show agreement with this observation, which can be explained by the variation in orbital hybridization at the Co/MgO interface in response to the weak electric fields. Our results on voltage control of DMI(VCDMI) suggest that research related to the voltage control of magnetic anisotropy for spin–orbit torque or the motion control of skyrmions might also have to consider the role of the external electric field on DMI as small voltages are generally used for the magnetoresistance detection.

Existence and Stability of Static Solutions of the Landau-Lifshitz Equation with Multi-direct Effective Field

We prove the existence of solutions of the static Landau-Lifshitz equation with multi- direct effective field and with Dirichlet boundary condition,and establish the stability of the solution of Landau-Lifshitz equation with respect to time.

Selection of proper combine harvesters to field conditions by an effective field capacity prediction model

Farmers have to finish their harvesting with high efficiency,because of time and cost.However,farmers are lacking knowledge and information required for selecting suitable combine harvesters and giving the conditions of their rice fields,because both information factors(combine harvester and field condition)impact the field capacity.The field capacity model was generated from combine harvesters with the Thai Hom Mali rice variety(KDML-105).Therefore,this study aimed to determine the prediction model for effective field capacity to combine harvesters when harvesting the Thai Hom Mali rice variety(KDML-105).The methods began by collecting data of 15 combine harvesters,such as field,crop,and machine conditions and operating times;to generate the prediction model for the KDML-105 variety.The prediction model was then validated using 12 combine harvesters that were collected similarly to the model creation.The results showed a root mean square error(RMSE)of 0.24 m^(2)/s for the model.The prediction model can be applied for farmers to select the proper combine harvesters and give their field conditions.

Effective field theory approach to lepton number violatingτdecays

We continue our endeavor to investigate lepton number violating(LNV)processes at low energies in the framework of effective field theory(EFT).In this work we study the LNV tau decaysτ^(+)→lP_(i)^(+)P_(J)^(+),where L=e.μand P_(i,j)^(+)denote the lowest-lying charged pseudoscalarsπ^(+),K^(+).We analyze the dominant contributions in a series of EFTs from high to low energy scales,namely the standard model EFT(SMEFT),the low-energy EFT(LEFT),and the chiral perturbation theory(χPT).The decay branching ratios are expressed in terms of the Wilson coefficients of dimension-five and-seven operators in SMEFT and the hadronic low-energy constants.These Wilson coefficients involve the first and second generations of quarks and all generations of leptons;thus,they cannot be explored in low-energy processes such as nuclear neutrinoless double beta decay or LNV kaon decays.Unfortunately,the current experimental upper bounds on the branching ratios are too weak to set useful constraints on these coefficients.Alternatively,if we assume the new physics scale is larger than 1 TeV,the branching ratios are well below the current experimental bounds.We also estimate the hadronic uncertainties incurred in applyingχPT toτdecays by computing one-loop chiral logarithms and attempt to improve the convergence of chiral perturbation by employing dispersion relations in the short-distance part of the decay amplitudes.

Astrophysical S-factor of the d（p,γ）~3 He process by effective field theory

We summarize the recent effective field theory （EFT） studies of low-energy electroweak reactions of astrophysical interest, relevant to big-bang nucleosynthesis. The zero energy astrophysical S（0） factor for the thermal proton radiative capture by deuteron is calculated with pionless EFT. The astrophysical S（0） factor is accurately determined to be S（0）=0.243 eV·b up to the leading order （LO）. At zero energies, magnetic transition M1 gives the dominant contribution. The M1 amplitude is calculated up to the LO. A good, quantitative agreement between theoretical and experimental results is found for all observables. The demonstrations of cutoff independent calculation have also been presented.

Chiral extrapolation of nucleon axial charge g_A in effective field theory

The extrapolation of nucleon axial charge gA is investigated within the framework of heavy baryon chiral effective field theory. The intermediate octet and decuplet baryons are included in the one loop calculation. Finite range regularization is applied to improve the convergence in the quark-mass expansion. The lattice data from three different groups are used for the extrapolation. At physical pion mass, the extrapolated gA are all smaller than the experimental value.

Nuclear axial currents from scale-chiral effective field theory

By incorporating hidden scale symmetry and hidden local symmetry in the nuclear effective field theory,combined with the double soft-pion theorem, we predict that the Gamow-Teller operator coming from the space component of the axial current should remain unaffected by the QCD vacuum change caused by the baryonic density,whereas the first forbidden beta transition operator coming from the time component should be strongly enhanced.While the latter has been confirmed for some time, the former was given support by a powerful recent ab initio quantum Monte Carlo calculation for light nuclei, which also confirmed the old？chiral filter hypothesis.＂ Formulated in terms of the Fermi-liquid fixed point structure of strong-coupled nuclear interactions, we offer an extremely simple resolution to the long-standing puzzle of the＂quenched g A,＂ gAeff ≈1 [1], found in nuclear Gamow-Teller beta transitions, giant Gamow-Teller resonances, and double beta decays.

Neutron-antineutron oscillations in the deuteron studied with NN and ■N interactions based on chiral effective field theory

Neutron-antineutron(n−n)oscillations in the deuteron are considered.Specifically,the deuteron lifetime is calculated in terms of the free-space n−n oscillation time τn−n based on NN and NN interactions derived within chiral effective field theory(EFT).This results in(2.6±0.1)×10^22τ2^n−n s,which is close to the value obtained by Dover and collaborators more than three decades ago,but disagrees with recent EFT calculations that were performed within the perturbative scheme proposed by Kaplan,Savage,and Wise.Possible reasons for the difference are discussed.

Towards the continuum coupling in nuclear lattice effective field theory Ⅰ: A three-particle model

Weakly bound states often occur in nuclear physics.To precisely understand their properties,the coupling to the continuum should be worked out explicitly.As the first step,we use a simple nuclear model in the continuum and on a lattice to investigate the influence of a third particle on a loosely bound state of a particle and a heavy core.Our approach is consistent with the Lüscher formalism.

Leading order relativistic hyperon-nucleon interactions in chiral effective field theory

We apply a recently proposed covariant power counting in nucleon-nucleon interactions to study strangeness S =-1 ΛN-Σ N interactions in chiral effective field theory. At leading order, Lorentz invariance introduces 12 low energy constants, in contrast to the heavy baryon approach, where only five appear. The Kadyshevsky equation is adopted to resum the potential in order to account for the non-perturbative nature of hyperon-nucleon interactions.A fit to the 36 hyperon-nucleon scattering data points yields χ2 16, which is comparable with the sophisticated phenomenological models and the next-to-leading order heavy baryon approach. However, one cannot achieve a simultaneous description of the nucleon-nucleon phase shifts and strangeness S =-1 hyperon-nucleon scattering data at leading order.

High-performance vertical GaN field-effect transistor with an integrated self-adapted channel diode for reverse conduction

A vertical GaN field-effect transistor with an integrated self-adapted channel diode(CD-FET)is proposed to improve the reverse conduction performance.It features a channel diode(CD)formed between a trench source on the insulator and a P-type barrier layer(PBL),together with a P-shield layer under the trench gate.At forward conduction,the CD is pinched off due to depletion effects caused by both the PBL and the metal-insulator-semiconductor structure from the trench source,without influencing the on-state characteristic of the CD-FET.At reverse conduction,the depletion region narrows and thus the CD turns on to achieve a very low turn-on voltage(V_(F)),preventing the inherent body diode from turning on.Meanwhile,the PBL and P-shield layer can modulate the electric field distribution to improve the off-state breakdown voltage(BV).Moreover,the P-shield not only shields the gate from a high electric field but also transforms part of C_(GD)to CGS so as to significantly reduce the gate charge(Q_(GD)),leading to a low switching loss(E_(switch)).Consequently,the proposed CD-FET achieves a low V_(F)of 1.65 V and a high BV of 1446 V,and V_(F),Q_(GD)and E_(switch)of the CD-FET are decreased by 49%,55%and 80%,respectively,compared with those of a conventional metal-oxide-semiconductor field-effect transistor(MOSFET).

Si–Ge based vertical tunnel field-effect transistor of junction-less structure with improved sensitivity using dielectric modulation for biosensing applications

A dielectric modulation strategy for gate oxide material that enhances the sensing performance of biosensors in junction-less vertical tunnel field effect transistors(TFETs)is reported.The junction-less technique,in which metals with specific work functions are deposited on the source region to modulate the channel conductivity,is used to provide the necessary doping for the proper functioning of the device.TCAD simulation studies of the proposed structure and junction structure have been compared,and showed an enhanced rectification of 10^(4) times.The proposed structure is designed to have a nanocavity of length 10 nm on the left-and right-hand sides of the fixed gate dielectric,which improves the biosensor capture area,and hence the sensitivity.By considering neutral and charged biomolecules with different dielectric constants,TCAD simulation studies were compared for their sensitivities.The off-state current IOFFcan be used as a suitable sensing parameter because it has been observed that the proposed sensor exhibits a significant variation in drain current.Additionally,it has been investigated how positively and negatively charged biomolecules affect the drain current and threshold voltage.To explore the device performance when the nanogaps are fully filled,half filled and unevenly filled,extensive TCAD simulations have been run.The proposed TFET structure is further benchmarked to other structures to show its better sensing capabilities.

A non-quasi-static model for nanowire gate-all-around tunneling field-effect transistors

Nanowires with gate-all-around(GAA) structures are widely considered as the most promising candidate for 3-nm technology with the best ability of suppressing the short channel effects,and tunneling field effect transistors(TFETs)based on GAA structures also present improved performance.In this paper,a non-quasi-static(NQS) device model is developed for nanowire GAA TFETs.The model can predict the transient current and capacitance varying with operation frequency,which is beyond the ability of the quasi-static(QS) model published before.Excellent agreements between the model results and numerical simulations are obtained.Moreover,the NQS model is derived from the published QS model including the current-voltage(I-V) and capacitance-voltage(C-V) characteristics.Therefore,the NQS model is compatible with the QS model for giving comprehensive understanding of GAA TFETs and would be helpful for further study of TFET circuits based on nanowire GAA structure.

Design and Analysis of Graphene Based Tunnel Field Effect Transistor with Various Ambipolar Reducing Techniques

The fundamental advantages of carbon-based graphene material,such as its high tunnelling probability,symmetric band structure(linear dependence of the energy band on the wave direction),low effective mass,and characteristics of its 2D atomic layers,are the main focus of this research work.The impact of channel thickness,gate under-lap,asymmetric source/drain doping method,workfunction of gate contact,and High-K material on Graphene-based Tunnel Field Effect Transistor(TFET)is analyzed with 20 nm technology.Physical modelling and electrical characteristic performance have been simulated using the Atlas device simulator of SILVACO TCAD with user-defined material syntax for the newly included graphene material in comparison to silicon carbide(SiC).The simulation results in significant suppression of ambipolar current to voltage characteristics of TFET and modelled device exhibits a significant improvement in subthreshold swing(0.0159 V/decade),the ratio of Ion/Ioff(1000),and threshold voltage(-0.2 V with highly doped p-type source and 0.2 V with highly doped n-type drain)with power supply of 0.5 V,which make it useful for low power digital applications.

Magnetic field‐enhanced water splitting enabled by bifunctional molybdenum‐doped nickel sulfide on nickel foam

Herein,we report bifunctional molybdenum-doped nickel sulfide on nickel foam(Mo-NiS_(x)/NF)for magnetic field-enhanced overall water splitting under alkaline conditions.Proper doping of Mo can lead to optimization of the electronic structure of NiS_(x),which accelerates the dissociation of H2O and the adsorption of OH−in the hydrogen evolution reaction(HER)and the oxygen evolution reaction(OER)processes,respectively.In addition,the magnetically active Mo-NiS_(x)/NF can further enhance the HER and OER activity under an applied magnetic field due to the magnetoresistance effect and the ferromagnetic(FM)exchange-field penetration effect.As a result,Mo-NiS_(x)/NF requires low overpotentials of 307 mV at 50mA cm^(−2)(for OER)and 136 mV at 10mA cm^(−2)(for HER)under a magnetic field of 10000 G.Furthermore,the electrolytic cell constructed by the bifunctional Mo-NiS_(x)/NFs as both the cathode and the anode shows a low cell voltage of 1.594 V at 10 mA cm^(−2)with optimal stability over 60 h under the magnetic field.Simultaneous enhancement of the HER and OER processes by an external magnetic field through rational design of electrocatalysts might be promising for overall water splitting applications.