Axion-Like Particles and the Higgs Decays h→PZ and h→Pe^+e^-

Axion-like particles（ALPs）are often defined as relatively light pseudoscalar particles and appear in many extensions of the Standard Model.Taking into account constraints on the free parameters from existing searches and explaining the g-2 deviation,we consider the contributions of ALPs with mass in the range of 1.5GeV

Constraints on axion-like particles from the observation of Galactic sources by the LHAASO

High-energy photons may oscillate with axion-like particles(ALPs)when they propagate through the Milky Way's magnetic field,resulting in an alteration in the observed photon energy spectrum.Ultra-high energy gamma-ray spectra,measured by the Large High Altitude Air Shower Observatory(LHAASO)up to O(1)PeV,provide a promising opportunity to investigate the ALP-photon oscillation effect.In this study,we utilize the gamma-ray spectra of four Galactic sources measured by the LHAASO,that is,the Crab Nebula,LHAASO J2226+6057,LHAASO J1908+0621,and LHAASO J1825-1326,to explore this effect.We employ the CLsmethod to set constraints on the ALP parameters.Our analysis of the observations of the four sources reveals that the ALPphoton coupling gaγis constrained to be smaller than 1.4×10^(-1)0GeV^(-1)for an ALP mass of~4×10^(-7)eV at 95%C.L.Combining the observations of the Crab Nebula from the LHAASO and other experiments,we find that the ALP-photon coupling may be set to approximately 7.5×10^(-11)GeV^(-1)for an ALP mass of~4×10^(-7)eV,which is similar to the CAST constraint.

Searching for the axion-like particle at the EIC

The axion-like particle(ALP)is a well motivated new particle candidate for beyond the standard model.In this study,we propose to probe the ALP via photon fusion scattering at the upcoming Electron-Ion Collider(EIC)with electron and proton energies of E_(e)=20 GeV and E_(p)=250 GeV,respectively.We can constrain the effective coupling strength between the ALP and photons to be 0.2 TeV^(-1)at the 2σconfidence level with an integrated luminosity of 300 fb^(-1)for the mass range m_(a)∈[5,40]GeV.Such bounds may be significantly improved if we consider the nucleus beam at the EIC.We also demonstrate that the limits from the EIC can be stronger than the off Zpole measurement at the LEP and light-by-light scattering with pp collisions at the LHC.

Precise evaluation of h→cc and axion-like particle production

We study the decay of the SM Higgs boson to a massive charm quark pair at the next-to-next-to-leading order QCD and next-to-leading order electroweak.At the second order of QCD coupling,we consider the exact calculation of flavour-singlet contributions where the Higgs boson couples to the internal top and bottom quark.Helpful information on the running mass effects related to Yukawa coupling may be obtained by analyzing this process.High precision production for h→cc within the SM makes it possible to search for new physics that may induce relatively large interactions related to the charm quark.As an example,we evaluate the axion-like particle associate production with a charm quark pair in the Higgs decay and obtain some constraints for the corresponding parameters under some assumptions.

Is the W-boson mass enhanced by the axion-like particle,dark photon,or chameleon dark energy?

The W-boson mass(m W=(80.4335±0.0094)Ge V)measured by the Collider Detector at Fermilab Collaboration is greater than the standard model(SM)prediction at a confidence level of 7σ,strongly suggesting the presence of new particles or fields.In the literature,various new particles and/or fields have been introduced to explain the astrophysical and experimental data,and their presence,in principle,may also enhance the W-boson mass.In this study,we investigate axion-like particle(ALP),dark photon(DP),and chameleon dark energy(DE)models for a solution to the W-boson mass excess.We find that the ALP and DP interpretations have been significantly narrowed down by global electroweak fits.The possibility of attributing the W-boson mass anomaly to the chameleon DE is ruled out by other experiments.

Polarized light-by-light scattering at the CLIC induced by axion-like particles

In this study,light-by-light(LBL)scattering with initial polarized Compton backscattered photons at the CLIC,induced by axion-like particles(ALPs),is investigated.The total cross sections are calculated assuming CP-even coupling of the pseudoscalar ALP to photons.The 95%C.L.exclusion region for the ALP mass ma and its coupling constant f is presented.The results are compared with CLIC bounds previously obtained for the unpolar-ized case.It is shown that the bounds onf for the polarized beams in the region m_(a)=1000-2000 GeV with colli-sion energy of 3000 GeV and integrated luminosity of 4000 fb^(-1)are on average 1.5 times stronger than the bounds for the unpolarized beams.Moreover,our CLIC bounds are stronger than those for all current exclusion regions for m_(a)>80 GeV.In particular,they are more restrictive than the limits that follow from the ALP-mediated LBL scatter-ing at the LHC.

Implications of axion-like particles from the Fermi-LAT and H.E.S.S.observations of PG 1553+113 and PKS 2155−304

We investigate the axion-like particle(ALP)-photon oscillation effect in the high-energy y-ray spectra of PG 1553+113 and PK.S 2155-304 measured by Fermi-LAT and H.E.S.S.The choice of extragalactic background light(EBL)model,which induces the attenuation effect in observed y-ray spectra,affects the ALP implications.For the ordinary EBL model that prefers a null hypothesis,we set constraints on the ALP-photon coupling constant at 95% C.L.as gay 5×10^(-11) GeV^(-1) for the ALP mass 〜10 neV.We also consider the CIBER observation of the cosmic infrared radiation,which shows an excess at wavelengths of -1μm after the substraction of foregrounds.High-energy gamma-rays from extragalactic sources at high redshifts would suffer from a more significant attenuation effect caused by this excess.In this case,we find that the ALP-photon oscillation would improve the fit to the observed spectra of PKS 2155-304 and PG 1553+113 and find a favored parameter region at 95%CL..

Exploring muonphilic ALPs at muon colliders

Axion-like particles(ALPs)are new particles that extend beyond the standard model(SM)and are extensively investigated.When considering ALPs within an effective field theory framework,their couplings with SM particles can be studied independently.It is a daunting task to search for GeV-scale ALPs coupled to muons in collider experiments because their coupling is proportional to the muon mass.However,a recent study by Altmannshofer,Dror,and Gori(2022)highlighted the importance of a four-point interaction,W-μ-νμ-a,as well as interactions from the chiral anomaly,whose couplings are not dependent on the muon mass.These interactions provide a new opportunity to explore muonphilic ALPs(μALPs)at the GeV scale.We explore variousμALP production channels at muon colliders withμALPs decaying into a pair of muons.In particular,we find that a pair of neutrinos accompanied by aμALP is the most effective channel to search forμALPs in the electrowek violating(EWV)scenario.In contrast,a photon plus aμALP becomes a better channel to search forμALPs in the electroweak preserving(EWP)scenario because there is no W-μ-νμ-a interaction in this situation.Most importantly,we find that the future bounds forμALPs in the EWV scenario are considerably stronger than those in the EWP scenario and the existing bounds for exploringμALPs with 1 GeV≤ma≲MW.

长寿命类轴子在正负电子对撞机的探寻研究

很多超标准模型理论都预言了长寿命粒子的存在,因此在对撞机上寻找长寿命粒子是发现和检验新物理的重要手段。模拟了未来正负电子对撞机上可能安装的远端探测器探寻了长寿命类轴子。考虑了类轴子伴随着一个光子产生,然后衰变为两个光子的信号过程,并利用相关程序模拟产生了质心系能量为91.2 GeV的对撞事例。研究结果表明,减小远端探测器与对撞点的距离、增大它的体积和将其安装在垂直于粒子束方向的位置,都有助于提高远端探测器对长寿命类轴子信号的探测能力。研究结果为将来探寻类轴子给予了启发,并为远端探测器的优化和建成提供了重要的参考。

Chapter 5 Dark Matter and New Physics Beyond the Standard Model with LHAASO

In order to reveal the nature of dark matter,it is crucial to detect its non-gravitational interactions with the standard model particles.The traditional dark matter searches focused on the so-called weakly interacting massive particles.However,this paradigm is strongly constrained by the null results of current experiments with high precision.Therefore there is a renewed interest of searches for heavy dark matter particles above TeV scale.The Large High Altitude Air Shower Observatory(LHAASO)with large effective area and strong background rejection power is very suitable to investigate the gamma-ray signals induced by dark matter annihilation or decay above TeV scale.In this document,we review the theoretical motivations and background of heavy dark matter.We review the prospects of searching for the gamma-ray signals resulted from dark matter in the dwarf spheroidal satellites and Galactic halo for LHAASO,and present the projected sensitivities.We also review the prospects of searching for the axion-like particles,which are a kind of well motivated light pseudo-scalars,through the LHAASO measurement of the very high energy gamma-ray spectra of astrophysical sources.

共振驱动的类轴子粒子探测实验设计与优化

为了进一步提高类轴子粒子传播的与自旋速度相关的新相互作用的实验灵敏度,本文研究了极化~3He作为探针的共振驱动方法来探测其与非极化物质间的新相互作用.首次将核磁共振Bloch方程中驱动磁场看作微扰,使用微扰法求解出Bloch方程的解析解,并计算出共振时有效磁场的放大倍数.其次分析了玻璃气室参数对有效磁场放大倍数的影响,优化设计后半径为1-2 mm的特种玻璃气室可使有效磁场放大倍数达到10~7.依托我们的特种玻璃气室制备设施和工艺,可使现有的实验探测灵敏度提高5个数量级.