We study two aspects of higher dimensional operators in standard model effective field theory.We first introduce a perturbative power counting rule for the entries in the anomalous dimension matrix of operators with e...We study two aspects of higher dimensional operators in standard model effective field theory.We first introduce a perturbative power counting rule for the entries in the anomalous dimension matrix of operators with equal mass dimension.The power counting is determined by the number of loops and the difference of the indices of the two operators involved,which in turn is defined by assuming that all terms in the standard model Lagrangian have an equal perturbative power.Then we show that the operators with the lowest index are unique at each mass dimension d,i.e.,(H^(†)H)^(d/2)for even d≥4,and(L^(T)εH)C(L^(T)εH)^(T)(H^(†)H)^((d-5)/2)for odd d≥5.Here H,L are the Higgs and lepton doublet,andε,C the antisymmetric matrix of rank two and the charge conjugation matrix,respectively.The renormalization group running of these operators can be studied separately from other operators of equal mass dimension at the leading order in power counting.We compute their anomalous dimensions at one loop for general d and find that they are enhanced quadratically in d due to combinatorics.We also make connections with classification of operators in terms of their holomorphic and anti-holomorphic weights.展开更多
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 rou...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.展开更多
Parton physics,when formulated as light-front correlations,are difficult to study non-perturbatively,despite the promise of lightfront quantization.Recently an alternative approach to partons have been proposed by re-...Parton physics,when formulated as light-front correlations,are difficult to study non-perturbatively,despite the promise of lightfront quantization.Recently an alternative approach to partons have been proposed by re-visiting original Feynman picture of a hadron moving at asymptotically large momentum.Here I formulate the approach in the language of an effective field theory for a large hadron momentum P in lattice QCD,LaMET for short.I show that using this new effective theory,parton properties,including light-front parton wave functions,can be extracted from lattice observables in a systematic expansion of 1/P,much like that the parton distributions can be extracted from the hard scattering data at momentum scales of a few GeV.展开更多
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...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.展开更多
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. Fi...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.展开更多
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 t...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.展开更多
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 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.展开更多
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 compon...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.展开更多
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...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.展开更多
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.Hornd...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.展开更多
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 pap...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.展开更多
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 ...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.展开更多
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 continuu...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.展开更多
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 ...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.展开更多
The future space-borne gravitational wave(GW)detectors would provide a promising probe for the new physics beyond the standard model that admits the first-order phase transitions.The predictions for the GW background ...The future space-borne gravitational wave(GW)detectors would provide a promising probe for the new physics beyond the standard model that admits the first-order phase transitions.The predictions for the GW background vary sensitively among different concrete particle physics models but also share a large degeneracy in the model buildings,which motivates an effective model description on the phase transition based on different patterns of the electroweak symmetry breaking(EWSB).In this paper,using the scalar N-plet model as a demonstration,we propose an effective classification for three different patterns of EWSB:(1)radiative symmetry breaking with classical scale invariance,(2)the Higgs mechanism in a generic scalar extension,and(3)higher-dimensional operators.We conclude that a strong first-order phase transition could be realized for(1)and(2)with a small quartic coupling and a small isospin of an additional N-plet field for the light scalar field model with and without the classical scale invariance,and(3)with a large mixing coupling between scalar fields and a large isospin of the N-plet field for the heavy scalar field model.展开更多
The magnetic behavior of the mixed ferro-ferrimagnetie alloy with （Aa Bb Cc）y D structure composed of Ising spins SA=1, SB = 5/2, SC= 2, and SD = 3/2 in the presence of the external magnetic field is investigated by...The magnetic behavior of the mixed ferro-ferrimagnetie alloy with （Aa Bb Cc）y D structure composed of Ising spins SA=1, SB = 5/2, SC= 2, and SD = 3/2 in the presence of the external magnetic field is investigated by the use of the effective field theory. The role of concentration b is discussed in this system in detail. Results show that for a =0.4, only when the concentration b is in the region 0.60 ≥b 〉 0.34 can the ferrimagnetic behavior be seen. Otherwise, the alloy shows ferromagnetic behavior.展开更多
Magnetic hysteresis and compensation behavior of a mixed spin-（1, 3/2） Ising model on a square lattice are investigated in the framework of effective field theory based on a probability distribution technique. The e...Magnetic hysteresis and compensation behavior of a mixed spin-（1, 3/2） Ising model on a square lattice are investigated in the framework of effective field theory based on a probability distribution technique. The effect of random crystal field, ferromagnetic and ferrimagnetic exchange interaction on hysteresis loops and compensation phenomenon are discussed. A number of characteristic phenomena have been reported such as the observation of triple hysteresis loops at low temperatures and for negative values of random crystal field. Critical and double compensation temperatures have been also found. The obtained results are also compared to some previous works.展开更多
The lightest electroweak baryon as a topological object is investigated by using a general effective Lagrangian of composite electroweak symmetry breaking and the spin-independent electroweak baryon-nucleon scattering...The lightest electroweak baryon as a topological object is investigated by using a general effective Lagrangian of composite electroweak symmetry breaking and the spin-independent electroweak baryon-nucleon scattering cross section is calculated. We explicitly show the masses of the electroweak baryons and the cross section as functions of the Peskin-Takeuchi S parameter and the ratio of the masses of axial-vector and vector composite bosons. We find that it is acceptable to regard the electroweak baryon as a dark matter candidate and the even number of technicolor is favored.展开更多
For understanding the hierarchies of fermion masses and mixing,we extend the Standard Model(SM)gauge group with U(1)_(X) and Z_(2) symmetry.The field content of the SM is augmented by three heavy right-handed neutrino...For understanding the hierarchies of fermion masses and mixing,we extend the Standard Model(SM)gauge group with U(1)_(X) and Z_(2) symmetry.The field content of the SM is augmented by three heavy right-handed neutrinos,two new scalar singlets,and a scalar doublet.U(1)_(X) charges of different fields are determined after satisfying anomaly cancellation conditions.In this scenario,the fermion masses are generated through higher-dimensional effective operators with O(1)Yukawa couplings.The small neutrino masses are obtained through type-1 seesaw mechanism using the heavy right-handed neutrino fields,whose masses are generated by the new scalar fields.We discuss the flavour-changing neutral current processes that arise due to the sequential nature of U(1)_(X) symmetry.We have written effective higher-dimensional operators in terms of renormalizable dimension-four operators by introducing vector-like fermions.展开更多
The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms.The band structure calculation shows that the band ...The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms.The band structure calculation shows that the band gaps of ZnO films with 2,4,and 6 layers are larger than the band gap of the bulk with wurtzite structure and decrease with the increase of film thickness.However,the four-layer ZnO nanofilms exhibit ferromagnetic phases for Mn concentrations less than 24% and 12% for Mn-doping performed in the whole layers and two layers of the film respectively,while they exhibit spin glass phases for higher Mn concentrations.It is also found,on the one hand,that the spin glass phase turns into the ferromagnetic one,with the substitution of nitrogen atoms for oxygen atoms,for nitrogen concentrations higher than 16% and 5% for Mn-doping performed in the whole layers and two layers of the film respectively.On the other hand,the spin-glass state is more stable for ZnO bulk containing 5% of Mn impurities,while the ferromagnetic phase is stable by introducing the p-type carriers into the bulk system.Moreover,it is shown that using the effective field theory for ferromagnetic system,the Curie temperature is close to the room temperature for the undamped Ruderman-Kittel-Kasuya-Yoshida（RKKY） interaction.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos.11025525,11575089the CAS Center for Excellence in Particle Physics(CCEPP)
文摘We study two aspects of higher dimensional operators in standard model effective field theory.We first introduce a perturbative power counting rule for the entries in the anomalous dimension matrix of operators with equal mass dimension.The power counting is determined by the number of loops and the difference of the indices of the two operators involved,which in turn is defined by assuming that all terms in the standard model Lagrangian have an equal perturbative power.Then we show that the operators with the lowest index are unique at each mass dimension d,i.e.,(H^(†)H)^(d/2)for even d≥4,and(L^(T)εH)C(L^(T)εH)^(T)(H^(†)H)^((d-5)/2)for odd d≥5.Here H,L are the Higgs and lepton doublet,andε,C the antisymmetric matrix of rank two and the charge conjugation matrix,respectively.The renormalization group running of these operators can be studied separately from other operators of equal mass dimension at the leading order in power counting.We compute their anomalous dimensions at one loop for general d and find that they are enhanced quadratically in d due to combinatorics.We also make connections with classification of operators in terms of their holomorphic and anti-holomorphic weights.
基金Supported by the National Natural Science Foundation of China under Grant No 11175088
文摘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.
基金partially supported by the U.S.Department of Energy(Grant No.DE-FG02-93ER-40762)the Office of Science and Technology in Shanghai Municipal Government(Grant No.11DZ2260700)the National Natural Science Foundation of China(Grant No.11175114)
文摘Parton physics,when formulated as light-front correlations,are difficult to study non-perturbatively,despite the promise of lightfront quantization.Recently an alternative approach to partons have been proposed by re-visiting original Feynman picture of a hadron moving at asymptotically large momentum.Here I formulate the approach in the language of an effective field theory for a large hadron momentum P in lattice QCD,LaMET for short.I show that using this new effective theory,parton properties,including light-front parton wave functions,can be extracted from lattice observables in a systematic expansion of 1/P,much like that the parton distributions can be extracted from the hard scattering data at momentum scales of a few GeV.
基金Supported in part by the Grants No.NSFC-12035008,No.NSFC-11975130by The National Key Research and Development Program of China under Grant No.2017YFA0402200by the CAS Center for Excellence in Particle Physics(CCEPP).XDM is supported by the MOST(109-2112-M-002-017-MY3,109-2811-M-002-535)。
文摘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.
基金Supported by National Natural Science Foundation of China(11475186)Sino-German CRC 110(NSFC 11621131001)
文摘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.
文摘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.
基金supported in part by a project (Y6Y2581B11) funded by 2016 National Postdoctoral Program for Innovative Talentssupported by the National Nat-ural Science Foundation of China (NSFC)(11847612,11690022,11851302,11675243,11761141011)+1 种基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB21010200,XDB23000000)supported by the 2019 International Postdoctoral Exchange Fellowship Program。
文摘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.
基金Supported by National Science Foundation of China(NSFC)(11475071,11547308)the Seeds Funding of Jilin University
文摘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.
基金supported in part by the DFG and the NSFC through funds provided to the Sino-German CRC 110"Symmetries and the Emergence of Structure in QCD"(DFG grant.no.TRR 110)the VolkswagenStiftung(93562)supported in part by The Chinese Academy of Sciences(CAS)President’s International Fellowship Initiative(PIFI)(2018DM0034)
文摘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.
基金Supported by National Key Research and Development Program of China (2021YFC2201901)and National Natural Science Foundation of China (12147103,11851302)。
文摘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.
基金Supported by the Doctoral Fund Project of Nanfang College,Guangzhou(2020BQ03)。
文摘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.
基金Supported by the National Natural Science Foundation of China (11735003, 11975041, 11961141004)。
文摘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.
基金financial support from the Deutsche Forschungsgemeinschaft (SFB/TRR 110,"Symmetries and the Emergence of Structure in QCD",grant no. TRR 110)by the Chinese Academy of Sciences (CAS) President’s International Fellowship Initiative (PIFI)(2018DM0034)+1 种基金by Volkswagen Stiftung (93562)by the Fundamental Research Funds for the Central Universities
文摘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.
基金Supported by the National Natural Science Foundation of China(11375024,11522539,11375120)the China Postdoctoral Science Foundation(2016M600845,2017T100008)the Fundamental Research Funds for the Central Universities
文摘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.
基金supported by the National Key Research and Development Program of China under Grant Nos.2021YFC2203004,2021YFA0718304,2020YFC2201501RGC is supported by the National Natural Science Foundation of China under Grants Nos.11947302,11991052,11690022,11821505 and 11851302+8 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)under Grant Nos.XDB23030100 and XDA15020701the Key Research Program of the CAS under Grant No.XDPB15the Key Research Program of Frontier Sciences of CAS.SJW is supported by the National Key Research and Development Program of China under Grant Nos.2021YFC2203004 and 2021YFA0718304the National Natural Science Foundation of China under Grant Nos.12422502 and 12105344the China Manned Space Project under Grant No.CMS-CSST-2021-B01JHY is supported by the National Science Foundation of China under Grant Nos.12022514,11875003 and 12047503the National Key Research and Development Program of China under Grant Nos.2020YFC2201501 and 2021YFA0718304the CAS Project for Young Scientists in Basic Research under Grant No.YSBR-006the Key Research Program of the CAS under Grant No.XDPB15.
文摘The future space-borne gravitational wave(GW)detectors would provide a promising probe for the new physics beyond the standard model that admits the first-order phase transitions.The predictions for the GW background vary sensitively among different concrete particle physics models but also share a large degeneracy in the model buildings,which motivates an effective model description on the phase transition based on different patterns of the electroweak symmetry breaking(EWSB).In this paper,using the scalar N-plet model as a demonstration,we propose an effective classification for three different patterns of EWSB:(1)radiative symmetry breaking with classical scale invariance,(2)the Higgs mechanism in a generic scalar extension,and(3)higher-dimensional operators.We conclude that a strong first-order phase transition could be realized for(1)and(2)with a small quartic coupling and a small isospin of an additional N-plet field for the light scalar field model with and without the classical scale invariance,and(3)with a large mixing coupling between scalar fields and a large isospin of the N-plet field for the heavy scalar field model.
基金The project supported by Shanghai Leading Academic Discipline Project under Grant,No.T0104
文摘The magnetic behavior of the mixed ferro-ferrimagnetie alloy with （Aa Bb Cc）y D structure composed of Ising spins SA=1, SB = 5/2, SC= 2, and SD = 3/2 in the presence of the external magnetic field is investigated by the use of the effective field theory. The role of concentration b is discussed in this system in detail. Results show that for a =0.4, only when the concentration b is in the region 0.60 ≥b 〉 0.34 can the ferrimagnetic behavior be seen. Otherwise, the alloy shows ferromagnetic behavior.
文摘Magnetic hysteresis and compensation behavior of a mixed spin-（1, 3/2） Ising model on a square lattice are investigated in the framework of effective field theory based on a probability distribution technique. The effect of random crystal field, ferromagnetic and ferrimagnetic exchange interaction on hysteresis loops and compensation phenomenon are discussed. A number of characteristic phenomena have been reported such as the observation of triple hysteresis loops at low temperatures and for negative values of random crystal field. Critical and double compensation temperatures have been also found. The obtained results are also compared to some previous works.
基金Supported by National Science Foundation of China(NSFC)under Grant Nos.11273013,11475071,11547308the Seeds Funding of Jilin Universitythe National Science Foundation of Jilin Province under Grant No.20180101228JC
文摘The lightest electroweak baryon as a topological object is investigated by using a general effective Lagrangian of composite electroweak symmetry breaking and the spin-independent electroweak baryon-nucleon scattering cross section is calculated. We explicitly show the masses of the electroweak baryons and the cross section as functions of the Peskin-Takeuchi S parameter and the ratio of the masses of axial-vector and vector composite bosons. We find that it is acceptable to regard the electroweak baryon as a dark matter candidate and the even number of technicolor is favored.
基金ARS thanks the Ministry of Minority Affairs,Government of India,for financial support through Maulana Azad National Fellowship under Grant No.F.82-27/2019(SA-Ⅲ).
文摘For understanding the hierarchies of fermion masses and mixing,we extend the Standard Model(SM)gauge group with U(1)_(X) and Z_(2) symmetry.The field content of the SM is augmented by three heavy right-handed neutrinos,two new scalar singlets,and a scalar doublet.U(1)_(X) charges of different fields are determined after satisfying anomaly cancellation conditions.In this scenario,the fermion masses are generated through higher-dimensional effective operators with O(1)Yukawa couplings.The small neutrino masses are obtained through type-1 seesaw mechanism using the heavy right-handed neutrino fields,whose masses are generated by the new scalar fields.We discuss the flavour-changing neutral current processes that arise due to the sequential nature of U(1)_(X) symmetry.We have written effective higher-dimensional operators in terms of renormalizable dimension-four operators by introducing vector-like fermions.
文摘The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms.The band structure calculation shows that the band gaps of ZnO films with 2,4,and 6 layers are larger than the band gap of the bulk with wurtzite structure and decrease with the increase of film thickness.However,the four-layer ZnO nanofilms exhibit ferromagnetic phases for Mn concentrations less than 24% and 12% for Mn-doping performed in the whole layers and two layers of the film respectively,while they exhibit spin glass phases for higher Mn concentrations.It is also found,on the one hand,that the spin glass phase turns into the ferromagnetic one,with the substitution of nitrogen atoms for oxygen atoms,for nitrogen concentrations higher than 16% and 5% for Mn-doping performed in the whole layers and two layers of the film respectively.On the other hand,the spin-glass state is more stable for ZnO bulk containing 5% of Mn impurities,while the ferromagnetic phase is stable by introducing the p-type carriers into the bulk system.Moreover,it is shown that using the effective field theory for ferromagnetic system,the Curie temperature is close to the room temperature for the undamped Ruderman-Kittel-Kasuya-Yoshida（RKKY） interaction.
