第二届粒子物理、天体物理和宇宙学前沿课题研讨会（2nd TOPAC: Topics of Particle, Astro and Cosmo Frontiers）将于2024年5月31日至6月2日在东南大学四牌楼校区举办。
前所未有的高能对撞数据、更高精度的粒子物理测量、不断升级的天文和宇宙学观测、迅速积累的引力波观测将我们带入了一个前所未有的境地：在粒子物理、天体物理和宇宙学的交叉领域不断涌现新的研究课题和热点，这也正逐渐加深我们对粒子物理、天文观测和早期宇宙的理解和认识。本会议将为相关领域专家提供一个相互交流的平台，深入探讨目前的研究现状和未来的可能方向，促进国内相关研究领域的发展。本次会议将涉及味物理，中微子、暗物质，天体物理、宇宙学、引力波等多个主题。
本次会议除口头报告外，还将提供海报展示的机会，欢迎大家提交口头报告和海报摘要、并积极参会。
TOPAC第一届会议于2023年在上海交通大学李政道研究所举办；本次是TOPAC会议的第二届，由东南大学主办，北京大学、上海交通大学协办。举办地在南京。
特别致谢：感谢东南大学艺术学院的尹文教授授权我们免费使用其艺术作品，用于制作本次会议的海报胸牌等物品。
会议有关事项：
会议时间：
2024年5月30日：报到
2024年5月31日至6月2日：线下报告
2024年6月3日：离会
会议注册：
网上注册截止日期：2024年4月15日
会议网址：https://indicotdli.sjtu.edu.cn/e/TOPAC2024
会议注册费：
教师：1500元
学生和博士后：1000元
组织委员会（拼音顺序）：
葛韶锋（上海交通大学）
何小刚（上海交通大学）
邵立晶（北京大学）
张永超（东南大学，大会主席）
会务秘书：
卢月
电话：15365073402
邮箱：2238854008@qq.com
The 2nd TOPAC (Topics of Particle, Astro and Cosmo Frontiers) will be held on May 30 – June 2, 2024 at the Sipailou Campus of Southeast University in Nanjing.
Unprecedented amount of highenergy collision data, higher precision measurements of particle physics experiments, upgrading astrophysical and cosmological observations, and quickly increasing gravitational wave measurements are bringing us into a new territory to be explored. Interdisciplinary research topics and highlights keep emerging across particle physics, astrophysics, and cosmology, which is enhancing our understanding of elementary particles, astrophysical observations, and the early university. This TOPAC meeting will provide a platform for experts in different fields to interact with each other to deeply discuss the current status and possible future directions. Hopefully this would push the development of involved directions. This TOPAC meeting covers multiple topics including flavor, neutrino, dark matter, astrophysics, cosmology, and gravitational wave.
In addition to the oral talks, this TOPAC meeting would also provide poster presentations. Abstracts for oral talks and poster presentations are highly welcome. You are welcome to register and participate the TOPAC meeting.
The 1^{st} TOPAC meeting was held at TsungDao Lee Institute, Shanghai Jiao Tong University in 2023. The 2^{nd} TOPAC meeting this year would be hosted by the Southeast University and assisted by Peking University and Shanghai Jiao Tong University.
Conference Items:
1. Conference Dates:
May 30, 2024: Arrival
May 30 – June 2, 2024: Onsite talks
June 3, 2024: Departure
2. Registration:
Deadline: April 30, 2024
Indico: https://indicotdli.sjtu.edu.cn/e/TOPAC2024
3. Registration fee:
Professors: CNY 1500
Students & Postdocs: CNY 1000
4. Organization Committee:
ShaoFeng Ge (Shanghai Jiao Tong University)
XiaoGang He (Shanghai Jiao Tong University)
Lijing Shao (Peking University)
Yongchao Zhang (Southeast University, Chair)
5. Secretary
Yue Lu
Cellphone: 15365073402
Email: 2238854008@qq.com
The Coherent Elastic NeutrinoNucleus Scattering (CEvNS) was predicted in 1974 but wasn't experimentally confirmed until 2017 due to its extremely low energy deposit, making detection challenging due to energy threshold and background levels. Liquid Xenon Time Projection Chambers (LXeTPCs) have shown excellence in dark matter searches and may serve as an ideal technology for detecting CEvNS. The RELICS experiment aims to utilize LXeTPC to detect reactor neutrinos via CEνNS. This report will cover the latest advancements in CEvNS detection.
Dark matter (DM) may be captured around a neutron star (NS) through DMnucleon interactions. We observe that the enhancement of such capturing is particularly significant when DMnucleon scattering crosssection depends on the relative velocity and/or momentum transfer. This increment could potentially lead to the formation of a black hole within the typical lifetime of the NS. As the black hole grows through the accretion of matter from the NS, it ultimately results in the collapse of the host. Utilizing the existing pulsar data J04374715 and J21243858, we derive the stringent constraints on the DMnucleon scattering crosssection across a broad range of DM masses.
Phase transition gravitational waves could be a novel probe for fundamental physics in the near future. Hence, precise calculation of phase transition gravitational waves is essential to revealing many unresolved puzzles in our universe. I will discuss a framework that could allow us to omit some unnecessary approximations and give a relatively more accurate calculation of gravitational waves generated by the sound wave mechanism. I will use a benchmark model to demonstrate the procedures of this framework and show the corresponding results.
Motivated by the most recent measurement of tau polarization in $Z\to \tau^+\tau^$ by CMS, we have introduced a new $U(1)_X$ gauge boson field X, which can have renormalizable kinetic mixing with the standard model $U(1)_Y$ gauge boson field Y.
In addition to the kinetic mixing of the dark photon, denoted as $\sigma$, there may also be mass mixing introduced by the additional Higgs doublet with a vacuum expectation value (vev) participating in $U(1)_X$ and electroweak symmetry breaking simultaneously.
The interaction of the Z boson with the SM leptons is modified by the introduction of the mixing ratio parameter $\epsilon$, which quantifies the magnitude of both the mass and kinetic mixing of the dark photon.
Initially, we use the tau lepton as an example to explore the Z boson phenomenology of the dark photon model with both kinetic and mass mixing. The goal is to determine the allowed parameter regions by taking into account constraints from the vector and axialvector couplings $g_{V,A}^\tau$, the decay branching ratio $Br(Z\to \tau^ \tau^+)$ and tau lepton polarization in $Z\to \tau^\tau^+$. We found that the mixing ratio plays important role in the Z boson features by choosing different $\epsilon$ values.
Furthermore, we aim to generalize our analysis from the taulepton case to include all fermions by conducting global fits. This allows us to identify viable regions by incorporating relevant fermion constraints and the W/Z mass ratio.
Correspondingly, we obtain the fit results with the kinetic mixing parameter $\sigma=0.074\pm0.021$, mixing ratio $\epsilon=1.37\pm0.46$, and dark photon mass $m_X=275\pm39$ GeV. Our global analysis indicates a preference for a dark photon mass larger than $m_Z$.
The ForwArd Search ExpeRiment (FASER,), is a recently installed detector at the LHC that can detect light, long lived particles. In this work we study the prospect of detecting light CPeven and CPodd scalars at the FASER. We develop the general formalism for the scalar production and decay from mesons at LHC, given modified couplings of the scalars to the SM particles, as well as summarizing the relevant GeVscale experiment constraints. We then analyze the reaches of light scalars in the large $\tan\beta$ region of the TypeI 2HDM, in which a light scalar with relatively long life time could be accommodated.
We present GKZ hypergeometric systems of fourloop vacuum Feynman integrals.
The discovery of the Higgs boson at the Large Hadron Collider (LHC) has opened a new era in particle physics.
Precise measurements of the properties of the Higgs boson are crucial for addressing several fundamental questions
in the field. These include understanding the mechanism behind electroweak symmetry breaking,
unraveling the origin of particle masses, and exploring potential sources of CP violation
that could explain the matterantimatter asymmetry in the universe, and so on.
In this talk, I will provide an overview of the recent advancements in Higgs physics,
both within the framework of the Standard Model (SM) and beyond.
By examining the latest research, we will gain insights into the properties and behavior of the Higgs boson,
shedding light on the fundamental workings of the universe.
Ref: https://arxiv.org/abs/2306.00641
Results from a wide range of searches targeting different experimental signatures with and without missing transverse momentum ($E^{miss}_T$) are used to constrain a TwoHiggsDoublet Model (2HDM) with an additional pseudoscalar mediating the interaction between ordinary and dark matter (2HDM+a). The analyses use up to 139 fb$^{−1}$ of protonproton collision data at a centreofmass energy $\sqrt{s}$ = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 20152018. The results from three of the most sensitive searches are combined statistically. These searches target signatures with large EmissT and a leptonically decaying Z boson; large $E^{miss}_T$ and a Higgs boson decaying to bottom quarks; and production of charged Higgs bosons in final states with top and bottom quarks, respectively. Constraints are derived for several common as well as new benchmark scenarios within the 2HDM+a.
Ref. ATLASCONF2024004
A first dedicated search is performed for dark matter particles produced in association with a resonantly produced pair of bquarks with m(bb) < 150 GeV using 140 fb$^{1}$ of protonproton collisions recorded by the ATLAS detector at a centerofmass energy of 13 TeV. This signature is expected in extensions of the Standard Model predicting the production of dark matter particles, in particular those containing dark Higgs bosons. This search uses a novel experimental method to extend the experimental reach to lower bbpair invariant masses, considers a wider range of dark Higgs boson interpretations and excludes new regions of parameter space for this model. For dark Higgs boson masses between 30 and 150 GeV, Z′ mediator masses up to 3.4 TeV and 4.8 TeV are excluded for benchmark scenarios.
We fully explore the prospect of using the off $Z$pole run at
future lepton colliders to probe the new physics (NP) beyond the Standard Model (SM) via dimension6 fourfermion effective operators. With interference between the dimesion6 operator and SM diagram contributions to the $e^+ e^ \rightarrow f \bar f$ scattering processes, the NP effects shows up at collision energy
off of the $Z$ pole. The $Z$ line shape scan is thus useful not just for the $Z$ mass and width measurements, but
also for NP probes. I will discuss the key observable and uncertainties involved in order to reach a realistic prospects for the reach.
Within the standard model, transverse single spin asymmetries in electron elastic scatterings can only arise from multiphoton exchanges. The A4@MAMI collaboration has measured the beam transverse single spin asymmetry in electronproton elastic scattering from 315 to 1508 MeV (Phys. Rev. Lett. 124, 122003 (2020)). The data are significantly different from theoretical calculations based on chiral perturbation (Phys. Rev. C 70, 054003 (2004)), unitarity (Phys. Rev. C 70, 045206 (2004)) and optical theorem (Phys. Rev. C 73, 055201 (2006)). Comparing with the unitary calculation, one may attribute the discrepancy to heavier intermediate states in twophoton exchanges (TPE) which are not included in the calculation. On the other hand, it requires the virtual photon to have large energy to excite highenergy/heavy states, one would expect contributions due to these intermediate states are small. From this point of view, the discrepancy is puzzling. Similar discrepancies were also observed at other laboratories, in both electronproton and electronlead scatterings, such as SAMPLE at MITBates (Phys. Rev. C 63, 064001 (2001)), Qweak at JLab (Phys. Rev. Lett. 125 112502 (2020)) and PREXII at JLab (Phys. Rev. Lett. 128, 142501 (2022)).
Another possible origin of these discrepancies could be Todd mechanisms beyond the standard model, such as a novel Tviolating interaction or an unanticipated twoboson exchange involving one virtual photon and one unknown Tconserving boson. However, the hadronic/nuclear uncertainties (such as possible intermediate states in TPE) in the theoretical calculations hamper us from investigating new physics via the transverse single spin asymmetry. In view of this, we propose to measure the transverse spin asymmetry in protonelectron (pe⃗) scattering instead of electronproton (e⃗ p) scattering using an unpolarized proton beam and polarized electrons in a polarized hydrogen gas target, which is planned at the hadronic accelerator HIAF, currently under construction at IMP, CAS. In pe scatterings, the effective energy (or Q2) is 2∼3 orders smaller than in ep scattering, only elastic intermediate state (i.e., proton) will be involved in twophoton exchanges. As a result, theory based on unitarity can provide calculations with little theoretical uncertainties. In experiments with polarized electron beams, asymmetries are usually very small due to relativistic effects. In scatterings between an unpolarized proton beam and a polarized electron target, no such effects present, as a result, the asymmetry will be larger by 4 orders, compared with e⃗ p experiments with electron beams of 1∼2 GeV. Consequently, systematical errors in the experiment will be reduced significantly. Given the above advantages, the transversely polarized pe⃗ scattering could be an attractive approach to search for new physics.
The seesaw mechanism is the most attractive mechanism to explain the small neutrino masses, which predicts the neutrinoless double beta decay (0νββ) of the nucleus. Thus the discovery of 0νββ is extremely important for future particle physics. However, the present data on the neutrino oscillation is not sufficient to predict the value of $m_{ee}$ as well as the neutrino mass $m^i_ν$. In this talk, by adopting a simple and consistent FroggattNielsen model, which can well explain the observed masses and mixing angles of quark and lepton sectors, we calculate the distribution of $m_{ee}$ and $m^i_ν$. Interestingly, a relatively large part of the preferred parameter space can be detected in the near future.
The representative effective field theories(EFTs) written in terms of Standard Model particles are Standard Model EFT(SMEFT) and Higgs EFT(HEFT). When we integrate out the heavy particles in the UV theory before electroweak symmetry breaking, it results in the SMEFT. On the other hand, if we integrate out the heavy particles taking into account the mass mixing in the symmetrybreaking phase, it results in the HEFT. Recently, the matching typeI, II, and III seesaw onto the SMEFT has been studied by the IHEP group and attracted a lot of attention. We have matched the typeII seesaw model onto the HEFT and compared our results with those of previous studies. We show quantitatively how much more accurate the HEFT description is than the SMEFT when the mass scale of the heavy particles is close to the electroweak scale.
Future muon colliders with centerofmass energy of $\mathcal{O}(110)$ TeV can provide a clean highenergy environment with advantages in searches for TeVscale axionlike particles (ALPs), pseudoNambu–Goldstone bosons associated with spontaneously broken global symmetries, which are widely predicted in physics beyond the Standard Model (SM). We exploit ALP couplings to SM fermions, and guided by unitarity constraints, build a search strategy focusing on the ALP decay to top quark pairs at muon colliders. It is found that a large parameter space of TeVscale ALPs with TeVscale decay constants can be probed by utilizing the ALPtop quark coupling.
Dark matter is one of the biggest mysteries in physics and astronomy today. While multiple dark matter candidates have been proposed, such as the axion and primordial black holes (PBHs), the interplay between them is not well understood. In this talk, I will focus on the formation of axion minihalos around PBHs and the condensation of axion stars inside them, and reveal distinct morphological characteristics of these structures compared to isolated axion star scenarios. Furthermore, I will explore the implications of these results when applied to gravitational microlensing from extended objects, providing constraints on the fraction of these objects contributing to microlensing events from the EROS2 survey.
Cosmic strings, theoretical onedimensional topological defects from the early universe, are a compelling source for studying dark matter production and gravitational wave (GW) emission. In this talk, I will focus on the production of gauge bosons and GW emission resulting from the decay of cosmic strings, discussing the constraints imposed by cosmological considerations. Specifically, I will examine the contribution of gauge bosons radiated from strings to dark matter and dark radiation respectively, which are strictly limited by the observed dark matter abundance and Cosmic Microwave Background data respectively. Moreover, I will assess the GW spectrum of this model against the forecasted capabilities of future GW observatories, with a particular emphasis on the Laser Interferometer Space Antenna. Following that, I will provide an overview of how these considerations influence the model parameters, specifically the gauge boson mass and the energy scale of U(1) symmetry breaking, offering insights into the potential for cosmic strings to inform our understanding of dark matter and GW astronomy.
We perform an analytic calculation of binary star evaporation rate under the gravitational potential from spatially extended dark solitons, and demonstrate that Milky Way’s wide binary star systems are susceptible to tidal perturbations from dark matter solitons of comparable and larger sizes. The GAIA data shows a sharp decrease of halolike wide binaries at large separations, indicating possible disruptions by dark solitons. We further put constraints on the mass and radius of solitons, which may correspond to ultralight bosonic dark matter around $10^{15}\,\rm eV$.
Combination of recent measurements for $h \to Z \gamma$ from ALTLAS and CMS shows an excess that the ratio of the observed and standard model (SM) predicted branching ratios $\mu = (\sigma\cdot{\cal B})_{\mathrm{obs}}/(\sigma\cdot{\cal B})_{\mathrm{SM}}$ is $2.2\pm 0.7$. If confirmed, it is a signal of new physics (NP) beyond SM. We study NP explanation for this excess. In general, for a given model it also affects the process $h \to \gamma \gamma$. Since measured branching ratio for this process agrees with SM prediction well, the model is constrained severely. We find that a minimally fermion singlets and doublet extended NP model can explain simultaneously the current data for $h \to Z \gamma$ and $h\to \gamma\gamma$. There are two solutions. One is the SM amplitude $c_Z^{\text{SM}}$ is enhanced by $\delta c_Z$ for $h \to Z \gamma$ to the observed value, but the $h \to \gamma \gamma$ amplitude $c_\gamma^{\text{SM}} +\delta c_\gamma$ is decreased to $c_\gamma^{\text{SM}}$ to give the observed branching ratio. This seems to be a contrived solution that although cannot be ruled out simply using branching ratio measurements. We, however, find another solution which naturally enhances the $h \to Z \gamma$ to the measured value, but keeps the $h \to \gamma\gamma$ close to its SM prediction. We also comment on some phenomenology of these new fermions.
The 2HDM+S is the singlet extension of 2HDM, which can accommodate more physics potential beyond the SM. We summarize the type II 2HDM+S model with various Higgs potential structures, and discuss several scenarios with different mass hierarchy. In this study, we concentrate on the mass eigenstate of the 2HDM+S, and test the parameter space of Higgs mixing angles and masses against the experimental constraints, including 125 GeV Higgs measurements, BSM Higgs direct searches, $STU$ and $B$physics observables. In particular, we study the exotic channels of $h_{125}\rightarrow A_S A_S$ and $h_{125}\rightarrow h_S h_S$ decays for the light singletlike Higgs scenarios $m_{h_S/A_S} < 62.5$ GeV, and determine the limit of Higgs mixing angles. Furthermore, we study the phenomenological distinction between 2HDM+S and 2HDM, and explore the indirect impact of the singlet admixture on the parameter space of $\cos(\beta\alpha_1)$, $\tan\beta$ and $m_A$.
Ultralight Dark Matter (ULDM) is one of the most promising DM candidates. Due to the Bose
enhancement, we find the annihilation rate of the ULDM in the presence of background photon
radiation can be greatly enhanced and produce a distinctive reflected electromagnetic wave with an
angular frequency equal to the ULDM mass. We propose to utilize such stimulated annihilation
to probe the ULDM with the electromagnetic quadratic coupling by emitting a beam of radio into
space. With a power of 50 MW emitter, we forecast the sensitivity of quadratic coupling in different
local halo models for lowfrequency radio telescopes, such as LOFAR, UTR2 and ngLOBO.
Future observation with nextgeneration largearea radio telescopes are expected to discover radio pulsars closely orbiting around Sagittarius A (Sgr A), the supermassive black hole (SMBH) in our Galactic Center (GC). Such a system can provide a unique laboratory for testing gravity theories , as well as the astrophysics around the GC. We will introduce our recent studies about prospects for using the SMBHpulsar system to test gravity. Including testing the nohair theorem in General Relativity, constraining the vector charge of Sgr A, probing the smallscale dark matter distribution around Sgr A and so on.
Spherical blackhole (BH) solutions have been found in the bumblebee gravity where a vector field nonminimally couples to the Ricci tensor. We study dynamic (in)stability associated with the gravitational and vector perturbations of odd parity against these bumblebee BHs. Under the planewave approximation, we find that bumblebee BHs do not suffer ghost instability, but gradient instability and tachyonic instability exist when the bumblebee charge exceeds certain values. The existence of the instabilities also depends on the nonminimal coupling constant $\xi$ that, there is a minimal value $\xi \sim 4\pi G$ with $G$ the gravitational constant for the instabilities to happen.
The theoretical consideration for bumblebee BH stability turns out to place stronger constraints on the parameter space than those from the recent observations of supermassive BH shadows by the Event Horizon Telescope Collaboration. It is also reminiscent of Penrose's cosmic censorship conjecture since the charge of bumblebee BHs cannot be too large due to the dynamic instabilities. Specifically, for $\xi(\xi16\pi G) > 0$, we find that the charge of a bumblebee BH cannot be larger than its mass.
We investigate the elastic scattering cross section between dark matter and protons using the DES Year 3 weak lensing data. This scattering induces a dark acoustic oscillation structure in the matter power spectra. To address nonlinear effects at low redshift, we utilize principal component analysis alongside a limited set of Nbody simulations, improving the reliability of our matter power spectrum prediction. We further perform a robust Markov Chain Monte Carlo analysis to derive the upper bounds on the DMproton elastic scattering crosssection, assuming different velocity dependencies. Our results, presented as the first Frequentist upper limits, are compared with the ones obtained by Bayesian approach. Compared with the upper limits derived from the Planck cosmic microwave background data, our findings from DES Year 3 data exhibit improvements of up to a factor of five. In addition, we forecast the future sensitivities of the China Space Station Telescope, the upcoming capabilities of this telescope could improve the current limits by approximately one order of magnitude.
We explore the theoretical description of oscillations in degenerate cases, presenting the formula for oscillation probability with neutrino oscillation as an illustrative example. We then apply the degenerate oscillation theory to study neutronantineutron oscillations, calculating the constraints of the new model on oscillation parameters, such as mixing angles, in neutron stars. Our findings provide valuable insights into the behavior of particle oscillations in extremely degenerate environments, offering strong constraints on neutronantineutron mixing, and further restrict the choice of GUT models.
Highenergy muon collider can play as an emitter of electroweak gauge bosons and thus leads to substantial vector boson scattering (VBS) processes. In this work, we investigate the production of heavy neutral lepton (HNL) $N$ and lepton number violation (LNV) signature through VBS at highenergy muon colliders. They provide clean and robust LNV signatures to tell the nature of Majorana HNLs and thus have more advantageous benefits than direct $\mu\mu$ annihilation. We analyze the potential of searching for Majorana HNL and obtain the exclusion limits on mixing $V_{\ell N}$ . Based on this samesign lepton signature, we also obtain the sensitivity of muon collider to the Weinberg operator.
The cores of dense stars are a powerful laboratory for studying feeblycoupled particles such as axions. Some of the strongest constraints on axionlike particles and their couplings to ordinary matter derive from considerations of stellar axion emission. In this work we study the radiation of axionlike particles from degenerate neutron star matter via a leptonflavorviolating coupling that leads to muonelectron conversion when an axion is emitted. We calculate the axion emission rate per unit volume (emissivity) and by comparing with the rate of neutrino emission, we infer upper limits on the leptonflavorviolating coupling $g_{ae\mu}$ that are at the level of $10^{6}$. For the hotter environment of a supernova, such as SN 1987A, the axion emission rate is enhanced and the limit is stronger, at the level of $10^{11}$, competitive with laboratory limits. Interestingly, our derivation of the axion emissivity reveals that axion emission via the leptonflavorviolating coupling is suppressed relative to the familiar leptonflavorpreserving channels by the square of the plasma temperature to muon mass ratio, which is responsible for the relatively weaker limits.
Considering the hierarchical structure of fermionic masses and the fermionic flavor mixing puzzles in the Standard Model, we propose to relate them by the seesaw mechanism, i.e. only the third generation of quarks and charged leptons achieve the masses at the tree level, the first two generations achieves masses through the mixings with the third generation, and the neutrinos achieve tiny Majorana masses by the socalled TypeI seesaw mechanism. This new picture at the fermion sector can explain simultaneously the flavor mixing puzzle and mass hierarchy puzzle in the SM. In addition, a flavordependent model (FDM) is proposed to realize the new mechanism, and observing the top quark rare decay processes $t\to ch$, $t\to uh$ and the lepton flavor violation processes $\mu\to3e,\;\tau\to3e,\;\mu\to3\mu$ is effective to test the proposed FDM.
The Witten effect implies the dynamics of axion and magnetic monopole. The ChoMaison monopole is a realistic electroweak monopole arisen in the WeinbergSalam theory. This monopole of TeV scale mass motivates the dedicated search for electroweak monopole at colliders. In this work we investigate the implication of KSVZ axion to the electroweak magnetic monopole. We use the spherically symmetric ansatz for the electroweak dyon and introduce the spherically symmetric function for the axion field. The effective Lagrangian is then shown in terms of the electroweak monopole part, the axion kinetic energy as well as the axion interaction term. We derive the consequent equations of motion in the presence of the axionphoton coupling and show the numerical results of the topological solutions. We then calculate the changed characteristics of the electroweak monopole such as the monopole mass and the electromagnetic charges, as well as the axion potential energy.
In this talk, we will discuss production of gravitational waves in the early universe within a first order phase transition involving a hidden sector feebly coupled with the visible sector. Unlike most existing studies on GWs from hidden sectors, which assume a constant temperature ratio between the hidden and visible sectors (i.e., ξ=T_h/T=const), we adopt a more precise approach using synchronous thermal evolution, denoted as ξ(T). We will discuss in detail how to obtain this ξ(T) and how it will influence our analysis on GWs from hidden sectors. As a result, we find that the twofield model predicts gravitational waves accessible at several proposed gravitational wave detectors: LISA, DECIGO, BBO, Taiji and their discovery would probe specific regions of the hidden sector parameter space and may also shed light on the nature of bubble nucleation in the early universe.
PandaX4T experiment is a dark matter direct detection experiment that employs a dualphase time projection chamber with a sensitive volume containing 3.7 tonnes of liquid xenon. Since 2020, the PandaX4T experiment has finished the data taking of run0 and run1 which has been used to test several dark matter models. In this talk, we will discuss the latest dark matter search results of the PandaX4T experiment.
If the terrestrial environment is permeated by dark matter, the levitation experiences damping forces and fluctuations attributed to dark matter. This paper investigates levitodynamics with multiple stochastic forces, including thermal drag, photon recoil, feedback, etc., assuming that all of these forces adhere to the fluctuationdissipation theorem. The ratio of total damping to the stochastic damping coefficient distinguishes the levitodynamics from cases involving only one single stochastic force. The heating and cooling processes are formulated to determine the limits of temperature change. All sources of stochastic forces are comprehensively examined, revealing that dark matter collisions cannot be treated analogously to fluid dynamics. Additionally, a meticulous analysis is presented, elucidating the intricate relationship between the fundamental transfer crosssection and the macroscopic transfer crosssection. While the dark damping coefficient is suppressed by the mass of the levitated particle, scattering can be coherently enhanced based on the amount of the component microscopic particle, the nucleus form factor, and the static structure factor. Hence, dark damping holds the potential to provide valuable insights into the detection of the macroscopic strength of fundamental particles. We propose experimental procedures for levitation and employ linear estimation to extract the dark damping coefficient. Utilizing current levitation results, we demonstrate that the fundamental transfer cross section of dark matter can be of the order $\sigma^{\rm D}_{T}\lsim {\cal O}(10^{26})\rm cm^2$
The possible Majorana nature of Neutrino is crucial for addressing profound questions such as the conservation of lepton number and the origins of the matterantimatter asymmetry in the universe. Experimentally searching for Majorana neutrinos is one of the most important fields in the forefront of fundamental physics. The PandaX4T detector, located in the China Jinping Underground Laboratory (CJPL), provides unique opportunities and highquality data for this type of research through the doubleweek decays of Xe136, Xe134 and Xe124. We will report the results and the progress of the doubleweek decay searches.
We investigates nonthermal leptogenesis from inflaton decays in the minimal extension of the canonical typeI seesaw model, where a complex singlet scalar $\phi$ is introduced to generate the Majorana masses of righthanded neutrinos (RHNs) and to play the role of inflaton. We systematically study nonthermal leptogenesis with the least model dependence. We give a general classification of the parameter space and find four characteristic limits by carefully examining the interplay between inflaton decay into RHNs and the decay of RHNs into the standardmodel particles. We find that the strongly nonthermal RHNs scenario occupies a large parameter space, including the oscillationpreferred $K$ range, and works well for a relativelylow reheating temperature $T^{}_{\rm RH} \geq 10^3~{\rm GeV}$, extending the lower bound on the RHN mass to $2\times 10^{7}~{\rm GeV}$.
We demonstrate that such a unified picture for inflation, neutrino masses, and baryon number asymmetry can be realized by either a ColemanWeinberg potential or a natural inflation potential for the inflaton. We find that nonthermal leptogenesis from inflaton decay offers a testable framework for the early Universe. The modelindependent investigation of nonthermal leptogenesis should be useful in exploring this direction.
Dark matter selfscattering is one of key ingredients for smallscale structure of the Universe, while dark matter annihilation is important for the indirect measurements. There is a strong correlation between the velocitydependent selfscattering cross section and the Sommerfeld enhancement factor for the dark matter annihilation cross section. In this study, we formulate a direct relation between them by the use of Watson's (initial state/final state) theorem and Omnès solution, and our formulation reproduces the Sommerfeld enhancement factor, which directly computed by solving the Schrödinger equation, from the scattering phase shift.
We demonstrate, for the first time, the freezein dark matter, constituting 100% of the relic density can completely explain the Galactic 511 keV photon signal. In the talk, I will present two simple models for illustration. In both scenarios, the freezein mechanism generates the entire dark matter relic density, and thus any types of additional dark matter components produced from other sources are unnecessary.
We go beyond the stateoftheart by combining first principal lattice results and effective field theory approaches as Polyakov Loop model to explore the nonperturbative dark deconfinementconfinement phase transition and the generation of gravitationalwaves in a dark YangMills theory. We further include fermions with different representations in the dark sector. Employing the PolyakovNambuJonaLasinio (PNJL) model, we discover that the relevant gravitational wave signatures are highly dependent on the various representations. We also find a remarkable interplay between the deconfinementconfinement and chiral phase transitions. In both scenarios, the future Big Bang Observer and DECIGO experiment have a higher chance to detect the gravitational wave signals. Most recently, via QuarkMeson model, we find the phase transition and thus gravitational wave signals will be significantly enhanced when the system is near conformal. In addition, we find that this effective field theory approach can be implemented to study the glueball dark matter production mechanism and for the first time provide a solid prediction of glueball dark matter abundance. Our prediction is an order of magnitude smaller than the existing glueball abundance results in the literature.

We discuss possible ways of extending the Standard Model quantum chromodynamics theory (QCD) theory and realize a firstorder phase transition at high temperatures above 1 GeV without running into current constraints from both heavy ion colliders and early cosmology. The phase transition is from a nonperturbative effect of the QCD and can have a great impact on the early universe, including gravitational wave signals detectable for future space interferometers.
We study gravitonphoton conversion in potential groundbased experiments. From graviton to photon transition, we calculate the cross section of gravitonatom interaction in the presence of spherical atomic electric fields; the obtained results hold for graviton energy around 100 keV to 1 GeV, and would be enhanced along the coherent length in extremely high frequencies; thus it gives a chance to catch MeV level gravitons from the universe with current neutrino facilities. From photon to graviton transition, we propose an experiment using entangled photon pairs to count missing photons passing through transverse magnetic tunnel, which could be used to verify the energy quantization of gravitational field.
本报告将讨论SU(2)矢量暗物质模型中拉矢量的一般构造方式，最终保证暗物质稳定性离散群的一般破缺方式，以及标量粒子的简并模式。
The environment around the black hole can provide us with a promising playground to study the dark matter properties because of the large dark matter density from accretion.
I will explore the multimessenger probes on the dark matter in the vicinity of black holes. More concretely, I will discuss (1) the multiwavelength signals covering the radio, CMB and gamma rays which can arise from the dark matter annihilation/decay (2) the gravitational wave signals from a black hole binary whose dynamics is affected by the dark matter.
Scalar field dark matter (SFDM) comprised of ultralight (m ∼ $10^{−22}$ eV) bosonic particles has received significant attention as a viable alternative to Cold Dark Matter (CDM), as it approximates CDM on large scales (≳ 1 Mpc) while potentially resolving some of its smallscale problems via kpcscale quantum interference. However, the basic SFDM model described by a free real field, a.k.a. fuzzy dark matter (FDM), is recently challenged by a catch22 problem: small boson masses yield the desired cores of dwarf galaxies but underpredict structure in the Lymanα forest, whereas large boson masses render FDM effectively identical to CDM. Therefore, we propose to study the complex SFDM model with a possible selfinteraction. A complex scalar field with U(1) symmetry results in the conservation of the associated Noether current, a new degree of freedom. We examine the dynamical implications of the Noether charge for largescale structure and the Cosmic Microwave Background. We also discuss potential tests of SFDM by the 21cm line from the Cosmic Dawn and by the gravitationalwave (GW) signal from spinning black holes. Furthermore, we demonstrate that the kination phase resulted from complex SFDM can amplify the primordial GW background and thus explain the recent pulsar timing array results.
Anomalous transport phenomena, such as the chiral magnetic effect, are originated from the chiral anomaly of gauge theories and recently developed in hadron and condensed matter physics. They can also cause interesting phenomena in the early Universe when the chirality is a good conserved quantity at the temperature much higher than 100 TeV. An example is the chiral plasma instability, where helical hypermagnetic fields are amplified from chiral asymmetry, which will be the source of the baryon asymmetry through the hypermagnetic helicity decay. In particular, we point out that a large lepton flavor asymmetry before the electroweak symmetry breaking with satisfying total BL to be zero, which has been thought not to be strongly constrained, generally corresponds to a large chiral asymmetry. This causes an amplification of a strong helical magnetic field, which leads to baryon overproduction. We find that this gives a stronger constraint on the lepton flavor asymmetry than the one given weakly from the BBN. In a similar way that a large lepton asymmetry before the electroweak symmetry breaking is constrained by the SU(2) electroweak sphalerons/chiral anomaly to avoid the baryon overproduction, we conclude that a large lepton flavor asymmetry is constrained by the U(1) hypergauge chiral anomaly.
We discuss the relation between the Higgs potential structure and primordial black hole (PBH) formations. Recently, it has been discussed that PBHs can be formed by firstorder phase transitions at the early Universe. In this talk, we consider the PBH formation mechanism through delayed firstorder phase transitions at the early Universe. If the phase transition is delayed, the large energy density fluctuation can be realized between symmetry broken and unbroken regions. If the density fluctuation can be larger than a certain criterion, the overdensity region may collapse to PBHs. We discuss the form of the Higgs potential needed to realize this PBH formation. In addition, we show that the commonly used exponential approximation of the bubble nucleation rate fails to capture such PBH formation.
The composite Higgs boson scenario assumes the existence of a new strongly coupled gauge sector with a softly broken approximate hyperflavor symmetry. At low energies the corresponding dynamics may be studied with help of the holographic techniques inspired by AdS/QCD. We present the bottomup softwall holographic model that admits a firstorder phase transition and, using a perturbation theory near the critical point, describe the production of the gravitational wave background by bubble nucleation processes in the thinwall approximation. We also employ the approximation of the large number of spacetime dimensions to describe inhomogeneous black hole solutions dual to the gauge sector behavior in the bubble wall.
Dark SHINE is a newly proposed fixedtarget experiment at SHINE (Shanghai high repetition rate XFEL and extreme light facility, being the 1st hard Xray FEL in China) under construction targeting completion in 2026. Dark SHINE aims to search for the new mediator, Dark Photon, bridging the Dark sector and the ordinary matter. In this work and presentation, we present the idea of this new project and 1st prospective study in search for Dark Photon decaying into light dark matter. It also provides the opportunity to incorporate broader scope of BSM search ideas such as ALP, utilizing the fixedtarget experiment of this type.
Recently, the Belle II collaboration announced the first measurement of $\mathcal B(B^+\to K^+\nu\bar\nu)$, which is found to be about $2.7\sigma$ higher than the SM prediction. We decipher the data with two new physics scenarios: the underlying $b\to s \nu\bar\nu$ transition is, besides the SM contribution, further affected by heavy new mediators that are much heavier than the EW scale, or amended by an additional decay channel with undetected light final states like dark matter or axionlike particles. These two scenarios can be most conveniently analyzed in the SMEFT and the dark SMEFT (DSMEFT) framework, respectively. We consider the flavour structures of the resulting effective operators to be either generic or satisfy the minimal flavour violation (MFV) hypothesis, both for the quark and lepton sectors.
We describe the SM quark/lepton masses in an SU(8) theory, where threegenerational SM fermions are nontrivially embedded. A set of d=5 operators that break the emergent global symmetries in the chiral fermion sector due to the Planck scale effects are sufficient to generate the light SM quark/lepton masses as well as the CKM mixing pattern, with one single SM Higgs doublet in the spectrum.
In view of both the latest LHCb measurement of $R_{K^{(*)}}$ and the new $2.7\sigma$ deviation reported by Belle II on $B^{+}\to K^{+}\nu\bar{\nu}$ decays, we present a fit to the $B$ meson anomalies for various one and two dimensional hypothesis including complex Wilson coefficients. We show in a modelindependent way that the generic nonuniversal $U(1)^{\prime}$ extensions of the SM, without flavour violation, fail to simultaneously fit those observables and corroborate that they can modify $\mathrm{BR}(B^{+}\to K^{+}\nu\bar{\nu})$ up to only a $10\%$. In view of this deficit, we propose a new way in which those models can accommodate the data at tree level by introducing lepton flavour violating couplings and nondiagonal elements of the charged lepton mixing matrix, with implications in future charged lepton flavour violation searches.
Recently we have build a MonteCarlo method that can obtain selfconsistent solutions of an evolving nuclear star cluster that contains a central massive black hole. Our method evolves the orbits of stellar objects by solving twodimensional (energy and angular momentum) FokkerPlanck equations given multiple mass components. In this study we apply our method to investigate the evolution of the rates of extreme mass ratio inspirals over cosmic time.
DAMPE是一颗空间宇宙线探测器，于2015年12月成功发射，并在轨运行多年，已经取得多项科学成果。DAMPE主要的科学目标有暗物质间接探测、宇宙线物理和高能伽马射线天文学。本报告重点介绍DAMPE的探测器研制，合作组组成和在轨运行情况。并介绍DAMPE已取得的科学成果，以及数据的物理解读。