TDLI-PKU BSM Workshop 2023: Looking to the Sky

1 Aug 2023, 08:00 → 4 Aug 2023, 16:40 Asia/Shanghai

Tsung-Dao Lee Institute/N6F-N600 - Lecture Room (Tsung-Dao Lee Institute)

Jason Evans (SJTU/TDLI), Jia Liu (Peking University), Yuichiro Nakai

An annual, now offline, workshop on beyond the Standard Model physics organized by Tsung-Dao Lee Institute (TDLI) and Peking University (PKU). The workshop will last three days from August 2nd to August 4th (August 1st for onsite registration) and take place at the Tsung-Dao Lee Institute in Shanghai. This year, our focus is on the interplay between particle physics, astrophysics and cosmology. The workshop will consist of offline talks from theorists throughout the world. By bringing together renowned researchers from around, we hope to promote theoretical particle physics in China.

Invited Speakers

Lorenzo Calibbi

Kohei Fujikura

Chengcheng Han

Qing-guo Huang

Yingying Li

Weikang Lin

Tao Liu

Zuowei Liu

Natsumi Nagata

Jing Ren

Sichun Sun

Xiaoping Wang

Zhongzhi Xianyu

Yidong Xu

Wen Yin

 

 

Organizers:

Jason Evans (TDLI & SPA, SJTU)
Jia Liu (PKU)
Yuichiro Nakai (TDLI & SPA, SJTU)
 

Workshop Secretary：

Wen Wang (E-mail: wang.wen@sjtu.edu.cn)

BSM2023会议手册PDF.pdf

Group photo.jpg

Tuesday, 1 August

23:00 → 23:10 Registration for the workshop: Book keeping purpose. Registration starts tomorrow.

Wednesday, 2 August

08:30 → 09:00 Registration for the workshop

09:00 → 10:10 Contributed talks (1)

09:00 Nonanalyticity and on-shell factorization of inflation correlators

Boundary correlators of dS bulk fields are important theoretical data for QFT in dS, and are also observables of cosmological collider physics. We will present recent progress in understanding the analytic structure of these inflation correlators with massive exchanges at either tree or loop orders. We will explain why the nonanalyticity of Inflation Correlators is phenomenologically important, and how such nonanalyticity can be diagnosed and computed via the on-shell factorization and the corresponding cutting rules.

Speaker: Zhong-Zhi Xianyu (Tsinghua University)

09:35 Light dark matter around eV mass range

I will talk about dark matter in the eV mass range.
The topic includes experimental hints, dark matter theory, and future experimental prospects.

Speaker: Wen Yin

eVDMTDLee.pdf

10:10 → 10:40 Coffee break

10:40 → 11:50 Contributed talks (1)

10:40 Millicharged particles from proton bremsstrahlung in the atmosphere

Light millicharged particles can be copiously produced from meson decays in cosmic ray collisions with the atmosphere, leading to detectable signals in large underground neutrino detectors. In this paper we study a new channel to produce millicharged particles in the atmosphere, the proton bremsstrahlung process. We find that the proton bremsstrahlung channel can produce a much larger flux of millicharged particles than the previously studied meson decay channel, resulting in an improvement on the SuperK limit by nearly one order of magnitude. Consequently, SuperK can probe new parameter space beyond the current leading limits from ArgoNeuT. We further note that the study on the proton bremsstrahlung process can be extended to other atmospherically produced light particles, and to millicharged particle searches in proton accelerators.

Speaker: Zuowei Liu

11:15 Neutrino magnetic moment portal: New constraints and multi-messenger opportunities

We scrutinize the hypothesis that gauge singlet fermions - sterile neutrinos - interact with Standard Model particles through the transition magnetic moment portal. These interactions lead to the production of sterile neutrinos in supernovae followed by their decay into photons and active neutrinos which can be detected at γ-ray telescopes and neutrino detectors, respectively. We find that the non-observation of active neutrinos and photons from sterile-neutrino decay associated to SN1987A yields the strongest constraints to date on magnetic-moment-coupled sterile neutrinos if their masses are inside a 0.1 − 100 MeV window. Assuming a near-future galactic supernova explosion, we estimate the sensitivity of several present and near-future experiments, including Fermi-LAT, e-ASTROGAM, DUNE, and Hyper-Kamiokande, to magnetic-moment-coupled sterile neutrinos. We also study the diffuse photon and neutrino fluxes produced in the decay of magneticmoment coupled sterile neutrinos produced in all past supernova explosions and find that the absence of these decay daughters yields the strongest constraints to date for sterile neutrino masses inside a 1 − 100 keV window

Speaker: Yingying Li (USTC)

11:50 → 13:30 Lunch break

13:30 → 15:15 Contributed talks (1)

13:30 A new first-order QCD phase transition in the early universe and gravitational waves

We extend the Standard Model quantum chromodynamics theory (QCD) theory and naturally realize a first-order phase transition at high temperatures above 1 GeV without running into current constraints from both heavy ion colliders and early cosmology. This phase transition is from a non-perturbative effect of the QCD and can have a great impact on the early universe, including gravitational wave signals detectable for future space interferometers.

Speaker: Sichun Sun (Beijing Institute of Technology)

14:05 Majoron Dark Matter from Type II Seesaw

The Type II seesaw mechanism is among the simplest extensions of the Standard Model accounting for neutrino masses. These are naturally induced by the vacuum expectation value (vev) of a scalar triplet coupling to the Standard Model Higgs and lepton doublets. In this talk, I will show that the "type-II majoron" - the pseudo Nambu-Goldstone boson that arises in this context if the lepton number is spontaneously broken by the vev of an additional scalar singlet - can naturally account for the dark matter (DM) observed in the universe. I will discuss majoron production in the early universe through both the freeze-in and misalignment mechanism and its signatures and constraints at direct and indirect DM searches.

Speaker: Prof. Lorenzo Calibbi

calibbi-TDLI-PKU-2023.pdf

14:40 TBA

TBA

Speaker: Prof. Qing-guo Huang

NewPhysics_gwb_tdli2308.pdf

15:15 → 15:45 Coffee break

15:45 → 16:20 Contributed talks (1)

15:45 TBA

TBA

Speaker: Prof. Tao Liu

PPA_TDL_2023Aug(1).pdf

16:20 → 17:20 Parallel talks (1)

16:20 pNGB Dark Matter, Cosmic Strings, and Gravitational Waves

We propose a UV completion model for pseudo-Nambu-Goldstone dark matter with a hidden U(1) gauge symmetry. Dark matter scattering off nucleons is highly suppressed by the UV scale and direct detection constraints can be easily evaded. The kinetic mixing between the hidden U(1) and the $\mathrm{U(1)_Y}$ gauge fields would lead to dark matter decays. The current bound on the dark matter lifetime implies that the UV scale should be higher than $10^9$ GeV. The spontaneous U(1) symmetry breaking at such a high scale would induce cosmic strings with high tension, resulting in a stochastic gravitational wave background with a high energy density. The constraints from current gravitational wave experiments as well as the future sensitivity are investigated. We find that most of the viable parameter points could be well studied in future gravitational wave experiments.

Speaker: Dr Zhao-Huan Yu (Sun Yat-sen University)

2308_pNGB_CS_GW_TDLI.pdf

16:40 Pathways to proton's stability via naturally small neutrino masses

In the present work, the connection between the smallness of the neutrino masses and the stability of the proton is studied. We analyze this connection from different perspectives: the smallness of neutrino mass and the proton stability originate from the same source, small neutrino masses lead to a long lived proton, and the smallness of the proton decay width as a cause of the naturally small neutrino masses. All the schemes are studied in detail and UV realizations are given. We discuss advantages of each scheme and outline further investigation directions.

Speaker: Oleg Popov (Shenzhen MSU-BIT University)

17:00 Searching for Evidence of Dark Energy in Milky Way

The origin and nature of dark energy is one of the most significant challenges in modern science. This research aims to investigate dark energy on astrophysical scales and provide a cosmology-independent method to measure its equation-of-state parameter $w$. To accomplish this, we introduce the concept of a perfect fluid in any static, curved spacetime, and express the energy-momentum tensor of the perfect fluid in a general isotropic form, namely Weinberg's isotropic form. This enables us to define an equation-of-state parameter in a physical and global manner. Within this theoretical framework, we demonstrate that the energy-momentum tensor of dark energy on different scales can take the general isotropic form. Furthermore, we explore the SdS$_{w}$ spacetime and establish its connection with dark energy in cosmology through the equation-of-state parameter $w$. In the SdS$_{w}$ spacetime, a repulsive dark force can be induced by dark energy locally. We then apply the concept of the dark force to realistic astrophysical systems using the Poisson equation. Finally, we find that an anomaly in the Milky Way rotation curve can be quantitatively interpreted by the dark force. By fitting the galactic curve, we are able to obtain the value of the equation-of-state parameter of dark energy, independently of specific dark energy models.

Speaker: Rui Zhang (IHEP)

DE_ruizhang.pdf

18:00 → 19:30 Banquet

Thursday, 3 August

09:00 → 10:10 Contributed talks (2)

09:00 Searching for ultralight dark matter from the sky

Dark matter (DM) constitutes 26.8% of the entire universe and is one of the most significant mysteries in modern physics. The study of its particle properties is a critical and forefront topic in particle physics and cosmology, unlocking a deeper understanding of the universe and establishing the inherent unity of science.Ultralight dark matter could address small-scale structure problems of the universe, which becomes more and more interesting. So, determining the mass and interaction of such particles remains a formidable challenge. Bosonic particles, such as dark photons and axions, correspond to vector and scalar bosons, respectively, and represent the only option for ultralight DM (≪eV). They offer the most promising avenue of exploration due to their strong theoretical motivations. Also based on the wave-like property of ultralight DM, it can be detected via different kinds of experiments all over the world.

Speaker: Xiaoping Wang (Beijing University)

XPWang-Shanghai.pdf

09:35 Neutron Star Heating: WIMP DM vs Others

Weakly Interacting Massive Particles (WIMPs) in the Universe accumulate in neutron stars (NSs) through their interactions with ordinary matter, and their annihilation inside the NS core causes late-time heating. It has been argued that this heating effect maintains the surface temperature of old NSs to be a few thousand K, which can be regarded as a smoking gun signature of dark matter (DM) heating in NSs. However, if other heating mechanisms exist, they may hide this effect of the DM heating, making it impossible to search for DM with this strategy. In fact, recent observations suggest that there may be some heating sources in NSs. In this talk, I will review such heating mechanisms and discuss their implications for the DM search using NS temperature observations.

Speaker: Prof. Natsumi Nagata

20230803.pdf

10:10 → 10:40 Coffee break

10:40 → 11:50 Contributed talks (2)

10:40 Detecting High-Frequency Gravitational Waves in Planetary Magnetosphere

High-frequency gravitational waves (HFGWs) carry a wealth of information on the early Universe with a tiny comoving horizon and astronomical objects of small scale but with dense energy. We demonstrate that the nearby planets, such as Earth and Jupiter, can be utilized as a laboratory for detecting the HFGWs. These GWs are then expected to convert to signal photons in the planetary magnetosphere, across the frequency band of astronomical observation. As a proof of concept, we present the first limits from the existing low-Earth-orbit satellite for specific frequency bands and project the sensitivities for the future more-dedicated detections. The first limits from Juno, the latest mission orbiting Jupiter, are also presented. Attributed to the long path of effective GW-photon conversion and the wide angular distribution of signal flux, we find that these limits are highly encouraging, for a broad frequency range including a large portion unexplored before.

Speaker: Jing Ren (Institute of High Energy Physics)

GWplanet_TDLi_v1.pdf

11:15 The 21-cm forest as a simultaneous probe of the dark and bright of the universe

Understanding the nature of dark matter and the first luminous objects of the universe is an indomitable urge of human beings. Various 21 cm signals from neutral hydrogen and various experiments have been proposed, or being used, to unveil the mysteries, but suffering from parameter degeneracies between particle physics and the unknown astrophysics at cosmic dawn. The 21-cm absorption lines from neutral hydrogen against higher-redshift background sources at cosmic dawn, known collectively as the 21-cm forest, are proposed to simultaneously probe the small-scale structures governed by the dark matter particle mass and the early heating history regulated by the formation of first galaxies. By measuring the 1-D power spectrum of the 21-cm forest on high-redshift quasar spectra, the upcoming Square Kilometre Array will be able to shed light on the nature of both the dark matter and the first galaxies.

Speaker: Dr Yidong Xu (National Astronomical Observatories, CAS)

YidongXu_21cmForest_20230803.pdf

11:50 → 13:30 Lunch break

13:30 → 15:10 Parallel talks (2)

13:30 Tachyonic Instability Induced Gravitational Waves at the PTA and CMB

When coupled to massless vector bosons, axion-like particles are known to generate a tachyonic instability as they start to roll down from the potential, which exponentially amplifies the vector boson wave functions. This drastic enhancement will in turn source gravitational waves that may be relevant for various experiments and observations. If the axion-like particles' rolling starts at a cosmic temperature of above MeV, the gravitational waves today will fall in the hunting range of pulsar timing arrays. Even the rolling starts much later, at after the cosmic recombination, the gravitational waves can still leave imprints on the polarizations of the cosmic microwave background. We will discuss the relevant model parameter space and the constraints in the corresponding scenarios.

Speaker: Sida Lu (HKUST)

TDLI_SL.pdf

13:50 Dark matter freeze-in gauged $U(1)_{B-3L_i}$ extensions

We consider a two-step freeze-in mechanism of a singlet fermionic dark matter (DM) $\chi$ in a gauged $U(1)_{B-3L_i}$, $i \in \{e,\mu,\tau\}$, extension of the Standard model (SM). The DM communicates with the SM only through flavorful vector-portal $Z_{B3L}$ due to its non-trivial charge $x$ under $U(1)_{B-3L_i}$, which also guarantees the stability of the DM over the age of the Universe for $x \neq \{\pm 3/2, \pm 3\}$. We derive constraints on the gauge coupling $g_{B3L}$ that guarantees to produce the correct observed relic abundance of DM, considering $Z_{B3L}$ to lie within the mass range of a few MeV up to a few GeV. We show, that various current and future proposed intensity frontier experiments will still be able to probe the tiny couplings required for DM freeze-in. Hence, one may be able to see the imprints of non-thermal DM which escaped detection prospects in DM direct searches.

Speaker: Lopamudra Mukherjee (Nankai University)

TDLI_workshop_Lopa.pdf

14:10 Search for Ultralight Dark Matter with Space-based Gravitational-Wave Interferometry

Ultralight particles are well-motivated in many physical theories beyond Standard Model of particle physics. They can also be Dark Matter candidates. If these ultralight fields couple to standard model particles, they would show as additional signals with characteristic features. We show future space-based gravitational-wave interferometry can serve as a sensitive method to detect these light DM and investigate the sensitivity with time-delay interferometry.

Speaker: Yong Tang (University of Chinese Academy of Sciences)

tdli-tangyong.pdf

14:30 Sphaleron in the Higgs Triplet Model

The Higgs triplet model (HTM) extends the Standard Model (SM) by one complex triplet scalar (also known as the type-II seesaw model), offering a simple and viable way to account for nonzero neutrino masses. On the other hand, the nontrivial couplings of the triplet to the gauge fields and to the SM Higgs field are expected to influence the topological vacuum structure of the SM and, consequently, the energy and field configuration of the electroweak sphaleron. The sphaleron process plays a crucial role in dynamically generating the baryon asymmetry of the Universe. In this work, we study the vacuum structure of the gauge and Higgs fields and calculate the saddle-point sphaleron configuration in the HTM. The coupled nonlinear equations of motion of the sphaleron are solved using the spectral method. We find that the inclusion of the triplet scalar could, in principle, significantly change the sphaleron energy compared with the SM. Nevertheless, at zero temperature, the current stringent experimental constraint on the vacuum expectation value of the triplet suppresses the difference. Interestingly, we find that there still exists some narrow parameter space where the sphaleron energy can be enhanced by up to 30% compared with the SM case.

Speaker: Bingrong Yu (IHEP)

Sphaleron in the HTM_Yu.pdf

Sphaleron in the HTM_Yu.pptx

14:50 Diagrammatic structures of the Nielsen identity

The Nielsen identity is crucial for the gauge dependence of various observables associated with the effective potential. Usually when calculated up to a definite order, it is difficult to acquire a gauge-independent result since the incomplete resummation processes. In the literature, Nielsen identity was usually induced through a path-integral way, while the discussions of the gauge-dependence up to a particular perturbative order were uncommon. In this talk, I would like to anatomize the Feynman diagrams to see how this identity works perturbatively. People can anticipate the origin of the perturbative imbalance of this identity through my calculations.

Speaker: Yi-Lei Tang (中山大学)

NielsenIdentity_ForSHJT.pdf

15:10 → 15:40 Coffee break

15:40 → 17:20 Parallel talks (3)

15:40 Macroscopic Dark Matter Detection with Extreme Mass Ratio Inspirals and mini-EMRIs

I will discuss the detection of macroscopic dark matter candidates such as primordial black holes, boson stars, etc, with a special kind of binary system, the extreme mass ratio inspirals, which is a main target for future space-based gravitational wave detectors, and emphasize its advantages in detection of subsolar exotic compact objects. I will also introduce the mini-EMRIs that can be searched for at LIGO.

Speaker: Huaike Guo (UCAS)

Huaike.pdf

16:00 Dark Conformal Phase Transition and Pulsar Timing Arrays

We will explore the possibility that the nano-Hz stochastic gravitational wave background recently reported by several Pulsar Timing Arrays is due to a first-order phase transition of a nearly conformal dark sector, using the dual radion effective potential formalism. The dark radiation from the secluded dark sector can alleviate the Hubble tension without violating the $\Delta N_{\rm eff}$ bound, and will be probed by future CMB-S4 experiment. We will also comment on the scenario where the dark sector decays into the visible sector.

Speaker: Sudhakantha Girmohanta (Tsung-Dao Lee Institute and Shanghai Jiao Tong University)

PTA_TDLI_presentation.pdf

16:20 Z portal to the dark sector through Z′ mediation

The exotic Z decays to a QCD-like dark sector provide unexplored opportunities at colliders. In this talk, we explore the region where the Z portal is generated by a dark Z′. The phenomenological signatures of light Z' are studied, with both dark shower signals in Z decays and rare decays of B hadrons taken into account.

Speaker: Xuhui Jiang (HKUST)

PDF_Zportal.pdf

16:40 Exploring Ultralight Scalar Assistance in Sterile Neutrino Dark Matter: Cold Spectrum and Unusual X/Gamma-ray Signatures

We present a scalar-driven sterile neutrino production model where the interaction with the ultralight scalar field modifies the oscillation production of sterile neutrinos in the early universe. The model effectively suppresses the production of sterile neutrinos at low temperatures due to the heavy scalar mass, resulting in a colder matter power spectrum that avoids constraints from small-scale structure observations. In this model, the dominant dark matter relic is from sterile neutrinos, with only a small fraction originating from the ultralight scalar. Furthermore, the model predicts a detectable X/Gamma-ray flux proportional to the cubic density of local sterile neutrinos for a light scalar mass due to the light scalar coupling tosterile neutrinos. This distinguishes our model from normal decaying dark matter, which has a linear dependence on the density. In addition, the model predicts a potential low-energy monochromatic neutrino signal that can be detectable by future neutrino telescopes.

Speaker: 雨轩 何 (Peking university)

sterileNeu.pdf

17:00 Searching for Ultralight Dark Matter Conversion in Solar Corona using LOFAR Data

Ultralight axions and dark photons are well-motivated dark matter (DM) candidates. The axion DM and dark photon DM (DPDM) can resonantly convert into electromagnetic (EM) waves in the solar corona when their mass is equal to the solar plasma frequency. The resultant EM waves are mono-chromatic in the radio-frequency range with an energy equal to the DM mass, which can be detected via radio telescopes for solar observations. We search for converted mono-chromatic signals in the observational data of the high-sensitivity Low Frequency Array (LOFAR) telescope. We find the upper limit on the kinetic mixing coupling between DPDM and photon can reach $10^{-13}$ in the frequency range $30-80$ MHz, which is about one order of magnitude better than the existing constraint from the cosmic microwave background (CMB) observation. In addition, we also get the upper limit on the axion-photon coupling in the same frequency range, which is better than the constraints from Light-Shining-through-a-Wall experiments but does not exceed the CAST or other astrophysical bounds.

Speaker: Yan Luo

Y.Luo-TDLI 2023.pdf

Friday, 4 August

09:00 → 10:10 Contributed talks (3)

09:35 Probing the dark matter and high-energy particle physics with low-energy neutrino astronomy

The often-considered dark matter (DM) candidates, e.g., WIMP and ALP, are in tension with observations, which motivates new proposals for DM. The recently proposed féeton dark matter, a B-L gauge boson with a small mass and feeble coupling to the standard sector, constitutes a well-motivated dark matter model consistent with cosmology, Seesaw mechanism, and leptogenesis. This model predicts nontrivial neutrino signals decayed from dark matter in the Milky Way and from distant galaxies, which are promising for the future with low-energy neutrino experiments. We name it the féeton dark matter.

Speaker: Weikang Lin (South-Western Institute for Astronomy Research)

Presentation_TDLI_PKU_BSM_workshop-2.pdf

10:10 → 10:40 Coffee break

10:40 → 11:50 Contributed talks (3)

10:40 Type II Seesaw leptogenesis

Type II seesaw leptogenesis

Speaker: Chengcheng Han (Sun Yat-sen university)

typeIIseesaw.pdf

11:15 Interactions between several types of cosmic strings

Cosmic strings are line-like topological defects which can be formed in the early universe. In this talk, I first review basic concepts and general features of cosmic strings. Then I will explain how to evaluate interaction energies of two cosmic strings, and discuss our recent results. I also discuss phenomenological implications of our results such as the formation of the bound state of cosmic strings.

Speaker: KOHEI FUJIKURA (U. Tokyo)

TDLI_talk.pdf

11:50 → 13:30 Lunch break