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BEGIN:VEVENT
SUMMARY:[online] A unified framework to study $f$-family of modified gravi
 ty theories
DTSTART;VALUE=DATE-TIME:20261109T023000Z
DTEND;VALUE=DATE-TIME:20261109T030000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2930@indico.itp.ac.cn
DESCRIPTION:Speakers: Saikat Chakraborty (Institute of Research and Develo
 pment\, Duy Tan University\, Vietnam)\nI will introduce a neat mathematica
 l framework that can be utilized to study\, in a unified manner\, differen
 t aspects of $f(R)\,\\\,f(T)\,\\\,f(G)$ or $f(Q)$ gravity. As an example o
 f the application of this framework\, I will show its applicability for a 
 comparative analysis between $f(R)$ gravity and the trivial FLRW connectio
 n branch of $f(Q)$ gravity\, with respect to the two following questions: 
 (1) provide a purely cosmographic measure on the deviation from GR based o
 n the current data and (2) the behaviour of the underlying theory (more pr
 ecisely\, of it's deviation from GR) given a certain cosmological evolutio
 n. Time permitting\, I will briefly introduce the direction of a further i
 nteresting application of this framework.\n\nhttps://indico.itp.ac.cn/even
 t/417/contributions/2930/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2930/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A Non Singular Cyclic Universe from Modified Gravity
DTSTART;VALUE=DATE-TIME:20261109T033000Z
DTEND;VALUE=DATE-TIME:20261109T040000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2966@indico.itp.ac.cn
DESCRIPTION:Speakers: Dhiraj Kuniyal (Department of Physics and Astrophysi
 cs\, University of Delhi\, Delhi 110007\, India)\nThe Big Bang singularity
  marks a fundamental breakdown of General Relativity\, yet all proposed qu
 antum gravitational remedies invoke microphysical assumptions beyond the o
 bservational reach. We show that a minimal\, purely classical modification
  of the gravitational potential --- preserving the inverse-square law wher
 e tested\, but free to depart at unmeasured scales --- is sufficient to pr
 oduce a non-singular\, cyclic universe. The resulting modified gravitation
 al formulation leads to a cosmic evolution exhibiting a bounce at a finite
  minimum size\, followed by a regime closely akin to the concordant $\\Lam
 bda$CDM model\, and an eventual collapse to another bounce. Cosmic Chronom
 eter\, Supernovae type Ia\, Baryon Acoustic Oscillation\, Cosmic Microwave
  Background and Nucleosynthesis data constrain both the new length scales\
 , implying a cycle period of ${\\simeq}\\\,89\\\,\\mathrm{Gyr}$\, and this
  framework --- subsuming a broad class of bounce scenarios within a single
  testable model --- opens a direct route for distinguishing cyclic cosmolo
 gies from $\\Lambda$CDM.\n\nhttps://indico.itp.ac.cn/event/417/contributio
 ns/2966/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2966/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Resolving the Cosmological $^7$Li Abundance Anomaly via Baryon Emi
 ssion from Evaporating Primordial Black Holes
DTSTART;VALUE=DATE-TIME:20261109T013000Z
DTEND;VALUE=DATE-TIME:20261109T020000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2928@indico.itp.ac.cn
DESCRIPTION:Speakers: Elena Arbuzova (Dubna State University and Novosibir
 sk State University)\nAlthough the standard model of Big Bang nucleosynthe
 sis successfully describes the formation of light elements\, it faces a we
 ll-known challenge: the observed abundance of lithium-7 is approximately t
 hree times lower than the theoretically predicted value. This work propose
 s a mechanism to resolve this primordial lithium deficit through the emiss
 ion of baryons by evaporating primordial black holes (PBHs). The lithium f
 raction can be efficiently reduced to the observed level via the transform
 ation of $^7$Li through nucleon capture by lithium nuclei. This capture pr
 ocess produces $^8$Li or $^8$Be isotopes\, which then rapidly decay into p
 airs of helium ($^4$He) nuclei. The analysis explores scenarios involving 
 both "hot" and "cool" PBHs.\n\nhttps://indico.itp.ac.cn/event/417/contribu
 tions/2928/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2928/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Inflation from Entropy: Inflationary Solutions in the Gravity from
  Entropy Framework
DTSTART;VALUE=DATE-TIME:20261109T030000Z
DTEND;VALUE=DATE-TIME:20261109T033000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2981@indico.itp.ac.cn
DESCRIPTION:Speakers: Udaykrishna Thattarampilly (Yangzhou University)\nGr
 avity from entropy proposes quantum relative entropy between the spacetime
  metric and the metric induced by geometry and matter fields as the fundam
 ental action for gravity. The resulting modified Einstein equations reduce
  to general relativity in the weak-coupling\, low-curvature limit\, while 
 departing from it at high curvature. In this talk\, I derive the Friedmann
 -equation analogues of GfE for a spatially flat FLRW universe and show tha
 t the vacuum equations admit inflationary solutions\, with no inflaton fie
 ld or added potential. This points to an entropic origin for inflation tha
 t avoids the need for a new scalar field. Assuming the standard relation b
 etween slow-roll parameters and CMB observables carries over to GfE\, the 
 theory predicts a viable primordial spectrum.\n\nhttps://indico.itp.ac.cn/
 event/417/contributions/2981/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2981/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A Template-Based Search for Large-Scale-Structure--Correlated Anis
 otropy in the Nanohertz Gravitational-Wave Background Using the Public NAN
 OGrav 15-Year Data Set
DTSTART;VALUE=DATE-TIME:20261109T010000Z
DTEND;VALUE=DATE-TIME:20261109T013000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2959@indico.itp.ac.cn
DESCRIPTION:Speakers: Yun Fang (Institute of Fundamental Physics and Quant
 um Technology\, Ningbo University)\nRecent PTA analyses reporting evidence
  for a nanohertz common-spectrum process motivate targeted tests of whethe
 r any anisotropic component of the stochastic gravitational-wave backgroun
 d (SGWB) is correlated with the nearby large-scale structure (LSS)\, as an
 ticipated for an astrophysical background dominated by supermassive black 
 hole binaries. We present the first Bayesian PTA likelihood analysis that 
 embeds an externally observed\, full-sky galaxy-survey LSS template direct
 ly as an overlap-reduction-function (ORF) component. Using the 2MASS Photo
 metric Redshift (2MPZ) galaxy catalog\, we construct low-multipole LSS--co
 rrelated ORF templates in two redshift slices ($0\n\nhttps://indico.itp.ac
 .cn/event/417/contributions/2959/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2959/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Generation and Detection of Chiral Gravitational Wave Backgrou
 nd
DTSTART;VALUE=DATE-TIME:20261109T003000Z
DTEND;VALUE=DATE-TIME:20261109T010000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2980@indico.itp.ac.cn
DESCRIPTION:Speakers: Yun-Long Zhang (NAOC(National Astronomical Observato
 ries\, CAS))\nChiral gravitational wave backgrounds are predicted in many 
 well-motivated mechanisms. We investigate the detection of Chiral GWBs usi
 ng a network of detectors under arbitrary configurations. We also propose 
 a dipole pulsar timing array\, which demonstrates sensitivity to Chiral gr
 avitational wave backgrounds from the nanohertz to microhertz regime.\n\nh
 ttps://indico.itp.ac.cn/event/417/contributions/2980/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2980/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Revisiting Primordial Black Hole Formation from Primordial Gravita
 tional Waves
DTSTART;VALUE=DATE-TIME:20261108T093000Z
DTEND;VALUE=DATE-TIME:20261108T100000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2984@indico.itp.ac.cn
DESCRIPTION:Speakers: Peng Zhi-Zhang (Yangtze University)\nPrimordial grav
 itational waves generate radiation density perturbations at second order\,
  providing a possible connection between small-scale tensor power and prim
 ordial black hole (PBH) formation. In this talk\, we revisit this connecti
 on using a finite-time semianalytic solution for arbitrary source momenta.
  The solution retains the regular homogeneous contribution fixed by the in
 itial spatial curvature and separates it from the subsequent tensor source
 . For Gaussian primordial tensors\, we calculate the probability distribut
 ion of the quadratic density contrast smoothed at horizon reentry and comp
 are the resulting PBH abundance estimates with a Gaussian density approxim
 ation. We examine how the positive density tail depends on the specified i
 nitial geometry and illustrate the effects of finite-width tensor spectra.
  We also assess perturbative validity by evaluating the tensor strength in
  regions exceeding the adopted density threshold. In the cases studied\, t
 he inferred tensor powers and the conditional mean squared tensor amplitud
 es are of order unity. These results clarify the assumptions underlying PB
 H bounds on primordial gravitational waves and motivate nonlinear evolutio
 n with a collapse criterion calibrated for tensor-induced density profiles
  and shear.\n\nhttps://indico.itp.ac.cn/event/417/contributions/2984/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2984/
END:VEVENT
BEGIN:VEVENT
SUMMARY:How Does a Thermal Medium Affect Primordial Gravitational Waves?
DTSTART;VALUE=DATE-TIME:20261108T090000Z
DTEND;VALUE=DATE-TIME:20261108T093000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2970@indico.itp.ac.cn
DESCRIPTION:Speakers: Atsuhisa Ota (Chongqing University)\nA thermal mediu
 m modifies the propagation of gauge fields\, producing collective excitati
 ons with a plasmon gap. Does it affect primordial gravitational waves in t
 he same way? For gravity\, the thermal soft scale coincides with the Hubbl
 e rate\, making cosmic expansion essential to answering this question. In 
 this talk\, I compute the linear response of thermal radiation\, modeled b
 y a conformal scalar\, to metric perturbations on a spatially flat FLRW ba
 ckground. The calculation retains both retarded and contact contributions 
 and satisfies the diffeomorphism Ward identities. Although the adiabatic d
 ispersion relation exhibits a gap\, $\\omega_p^2=8\\mathcal H^2/5$\, with 
 $\\mathcal H$ the conformal Hubble rate\, superhorizon tensor modes remain
  conserved when the initial-time boundary of the retarded response is reta
 ined. The real-time evolution reproduces Weinberg’s gravitational-wave d
 amping\, with amplitude suppression accumulating around horizon reentry. I
  also explain how the superhorizon growth found in our earlier analyses ar
 ose from discarding the response history and adopting a state prescription
  incompatible with the Ward identities. These results clarify how a therma
 l collective gap coexists with conserved primordial perturbations and why 
 cosmological evolution requires a real-time treatment.\n\nhttps://indico.i
 tp.ac.cn/event/417/contributions/2970/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2970/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tracing out massive fields in cosmology
DTSTART;VALUE=DATE-TIME:20261108T083000Z
DTEND;VALUE=DATE-TIME:20261108T090000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2941@indico.itp.ac.cn
DESCRIPTION:Speakers: Guanhao Sun (Chongqing University)\nCosmological cor
 relators are calculated through the in-in formalism in (quasi-)de Sitter b
 ackground. Their effective description is best represented by a reduced de
 nsity matrix. In this talk\, I will first review the differences between t
 he usual EFT used in scattering amplitude calculations and the Schwinger-K
 eldysh EFT for correlators. I will then discuss the reduced density matrix
  for a light field at finite time\, obtained by tracing out a massive fiel
 d in a quasi-single-field model with non-linear couplings. The trace gener
 ates branch-mixing terms which are generally present in the Schwinger-Keld
 ysh formalism. Explicit calculations of the effective description and the 
 bispectrum will be shown for a conformally coupled massive field. I will t
 hen discuss how a local effective field theory is obtained through a large
  mass expansion of the exact non-local effective description. Finally\, I 
 will study the symmetry and Schwinger-Keldysh constraints on the reduced d
 ensity matrix.\n\nhttps://indico.itp.ac.cn/event/417/contributions/2941/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2941/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Scalar Induced Gravitational Waves Probing Phase Transitions in th
 e Standard Model and Beyond
DTSTART;VALUE=DATE-TIME:20261108T073000Z
DTEND;VALUE=DATE-TIME:20261108T080000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2978@indico.itp.ac.cn
DESCRIPTION:Speakers: Peizhi Du ()\nScalar induced gravitational waves (SI
 GW) are a powerful probe of dynamics in the Standard Model and BSM models 
 in the early Universe. In particular\, the equation of state and sound spe
 ed have a non-trivial time dependence during phase transitions\, which wil
 l impact the spectrum of induced GWs. In this talk\, I will present a deta
 iled calculation of SIGW in a general time-dependent thermal bath. We deri
 ve general initial conditions for metric perturbations in the superhorizon
  limit\, and explain special features of the GW spectrum associated with p
 hase transitions. I will show that the QCD crossover can leave observable 
 features in the Pulsar Timing Array window\, while BSM phase transitions\,
  such as in composite Higgs models\, can be probed by LISA\, Taiji and Tia
 nQin.\n\nhttps://indico.itp.ac.cn/event/417/contributions/2978/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2978/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Audible curvaton: modulated phase transition as the origin of larg
 e-scale curvature perturbations and gravitational wave anisotropies
DTSTART;VALUE=DATE-TIME:20261108T070000Z
DTEND;VALUE=DATE-TIME:20261108T073000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2973@indico.itp.ac.cn
DESCRIPTION:Speakers: Wenyuan Ai (Shanghai Jiao Tong University)\nI will d
 iscuss a new mechanism for generating primordial large-scale curvature per
 turbations and gravitational wave (GW) anisotropies via a first-order phas
 e transition modulated by a light spectator field. The spectator acquires 
 fluctuations during inflation\, which come into play at a post-inflation p
 hase transition by modulating the bubble nucleation rate. Such a modulatio
 n induces spatial variations in the transition time and characteristic bub
 ble scale\, producing the observed amplitude of primordial curvature pertu
 rbations together with sizable\, correlated GW anisotropies. We identify a
  benchmark with GW anisotropies potentially observable by future space-bas
 ed detectors and local primordial non-Gaussianity within reach of next-gen
 eration large-scale-structure surveys.\n\nhttps://indico.itp.ac.cn/event/4
 17/contributions/2973/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2973/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mapping the ALPs: A Naturalness Map for Axions and ALPs
DTSTART;VALUE=DATE-TIME:20261108T063000Z
DTEND;VALUE=DATE-TIME:20261108T070000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2947@indico.itp.ac.cn
DESCRIPTION:Speakers: Andrew Fowlie (XJTLU)\nThe axion solution to the str
 ong CP problem is only as robust as the Peccei-Quinn symmetry it relies on
 \, and quantum gravity is expected to break it. We quantify the resulting 
 axion quality problem using principled measures of fine-tuning\, and show 
 that the cost is severe. For the QCD axion to account for the observed dar
 k matter\, Planck-suppressed symmetry-breaking operators must be absent up
  to mass dimension $d \\ge 12$\; the naturalness penalty for failing to re
 alize this protection can exceed a Bayes factor of $10^{10}$. Extending th
 e analysis to generic axion-like particles\, we map the axion mass-decay c
 onstant plane by the degree of UV protection required\, and find that larg
 e portions of the sensitivity reach of laboratory experiments are already 
 fine-tuned at the part-per-million level or worse. We argue that quality\,
  not mass\, is the central naturalness question for the axion program.\n\n
 https://indico.itp.ac.cn/event/417/contributions/2947/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2947/
END:VEVENT
BEGIN:VEVENT
SUMMARY:From Ultralight to Macroscopic Dark Matter: A Window into the Dark
  Sector with Gravitational Waves
DTSTART;VALUE=DATE-TIME:20261108T060000Z
DTEND;VALUE=DATE-TIME:20261108T063000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2955@indico.itp.ac.cn
DESCRIPTION:Speakers: Andrew Miller (ICTP - AP / University Chinese Academ
 y of Sciences)\nDark matter may leave observable signatures in gravitation
 al-wave detectors through a remarkably broad range of physical mechanisms.
  In this talk\, I will discuss recent searches using data from the fourth 
 observing run of the LIGO–Virgo–KAGRA detector network. First\, I will
  present a direct search for ultralight dark matter\, in which coherently 
 oscillating scalar\, vector\, and tensor fields can produce characteristic
  signals in gravitational-wave interferometers. I will then discuss search
 es for gravitational waves from inspiraling planetary-mass and asteroid-ma
 ss ultra-compact objects\, which could be primordial black holes. Finally\
 , I will discuss how related continuous-wave searches can probe ultralight
  bosons through gravitational radiation from boson clouds surrounding rota
 ting black holes. Together\, these searches illustrate how gravitational-
 wave detectors can function not only as observatories of conventional astr
 ophysical sources\, but also as sensitive experiments for exploring the na
 ture of dark matter.\n\nhttps://indico.itp.ac.cn/event/417/contributions/2
 955/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2955/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Human–AI Collaboration-Driven Cosmology Research
DTSTART;VALUE=DATE-TIME:20261107T083000Z
DTEND;VALUE=DATE-TIME:20261107T090000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2971@indico.itp.ac.cn
DESCRIPTION:Speakers: Jiajun Zhang (Shanghai Astronomical Observatory)\nIn
  modern cosmological research\, using cosmological numerical simulations t
 o study the evolution of the large-scale structure of the Universe has pro
 ven to be a highly effective technique. However\, cosmological numerical s
 imulations beyond the standard cosmological model require numerous modific
 ations to existing cosmological simulation frameworks. They are technicall
 y complex and have a high entry barrier\, so a large number of non-standar
 d cosmological models cannot be effectively validated. In recent years\, t
 he development of artificial intelligence technologies represented by larg
 e language models has brought profound changes to scientific research\; fo
 r example\, large language models such as DeepSeek have rapidly spread acr
 oss various areas of life. Based on the DeepSeek large language model\, we
  developed an agent for cosmological numerical simulations. This agent use
 s multi-agent collaboration technology and integrates functions such as li
 terature review\, code analysis\, and report generation\, allowing users t
 o generate complex cosmological numerical simulation software with a singl
 e sentence. After evaluation\, we found that the agent can effectively avo
 id generating hallucinations and produce work guides with real productive 
 capacity. Using these work guides\, we automatically developed cosmologica
 l numerical simulation software for models including SIDM and WDM. In term
 s of development efficiency\, compared with experienced developers\, the a
 gent is two orders of magnitude more efficient. The application of this ag
 ent will bring about a major revolution in numerical-simulation-based cosm
 ology research. Hundreds or thousands of models that previously could not 
 be tested by simulations will become testable\, and the most time- and exp
 ertise-consuming part of this field has been overcome. We believe that the
  human–AI collaboration method developed in this study can be extended t
 o a broader range of research fields and may bring about a profound transf
 ormation of research paradigms.\n\nhttps://indico.itp.ac.cn/event/417/cont
 ributions/2971/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2971/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Luminal scalar-tensor theories via couplings to photons
DTSTART;VALUE=DATE-TIME:20261107T093000Z
DTEND;VALUE=DATE-TIME:20261107T100000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2923@indico.itp.ac.cn
DESCRIPTION:Speakers: Arina Shtennikova (INR RAS & ITMP MSU)\nThe detectio
 n of GW170817 and its electromagnetic counterpart placed a stringent bound
  on the difference between the speeds of gravitational waves and light\, s
 everely restricting viable scalar-tensor models of dark energy. In particu
 lar\, large parts of Horndeski and beyond Horndeski theories appeared to b
 e ruled out as a description of late-time cosmic acceleration. In this tal
 k we revisit this conclusion. We argue that the constraint concerns the re
 lative propagation of gravitons and photons\, so a consistent treatment mu
 st include possible interactions between the dark energy scalar and the el
 ectromagnetic sector. Using Kaluza–Klein reductions of higher-dimensiona
 l scalar-tensor theories as a guiding principle\, we construct classes of 
 self-consistent scalar–vector–tensor theories within the DHOST framewo
 rk in which gravitational waves and light propagate with equal speeds on c
 osmological backgrounds. We discuss which of these couplings cannot be rem
 oved by conformal or disformal field redefinitions\, the fate of gravitati
 onal wave decay into dark energy\, and the implications for screening mech
 anisms and observational tests.\n\nhttps://indico.itp.ac.cn/event/417/cont
 ributions/2923/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2923/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tomography of cosmic birefringence induced by 3-form dark energy
DTSTART;VALUE=DATE-TIME:20261107T063000Z
DTEND;VALUE=DATE-TIME:20261107T070000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2986@indico.itp.ac.cn
DESCRIPTION:Speakers: Kohei Kamada (HIAS-UCAS)\n3-form dark energy shows a
  similar behavior to but distinguishable one from that of a scalar field i
 n an expanding universe\, and its tensorial structure allows for unique co
 uplings that cannot be experienced by canonical scalars.\nWe here explore 
 the possibility that 3-form dark energy can explain the cosmic birefringen
 ce angle β~0.3°\, as suggested by observations of the CMB polarization.\
 nWe consider two EFT-inspired couplings between the 3-form and the photon\
 , finding a dimension-4 operator is a candidate explanation\, moreover pre
 dicting a photon mass around the Hubble scale.\nThe profiles for β(z) fro
 m the model can mimic those from ALP dark energy or ALP dark matter\, or b
 e distinguishable\, depending on the field configuration in the early univ
 erse\, which may be tested by precise measurements of CMB polarization or 
 radio galaxies.\n\nhttps://indico.itp.ac.cn/event/417/contributions/2986/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2986/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cosmological studies with cosmic microwave background and radio ob
 servations
DTSTART;VALUE=DATE-TIME:20261107T090000Z
DTEND;VALUE=DATE-TIME:20261107T093000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2926@indico.itp.ac.cn
DESCRIPTION:Speakers: Chang Feng (University of Science and Technology of 
 China)\nObservations of the cosmic microwave background (CMB) and radio wa
 velengths can probe multiple evolutionary stages spanning the early to lat
 e Universe\, which feature large-scale structures and long-timescale proce
 sses. These observations are therefore of fundamental importance for inves
 tigating core physical problems concerning dark matter\, dark energy\, and
  gravitational waves. Future CMB polarization observations\, with unpreced
 ented sensitivity and resolution\, may detect more exotic early- and late-
 Universe polarization signals\, posing potential challenges to the standar
 d cosmological model. The CMB formed when photons decoupled from the photo
 n-baryon plasma during hydrogen recombination\, as free electrons were cap
 tured to form neutral atoms. Similarly\, the redshifted 21 cm line of neut
 ral hydrogen can also trace dark-matter-dominated large-scale structures a
 cross a wide range of redshifts and spatial scales. This talk will present
  the scientific objectives\, recent research progress\, and future plans f
 or cosmological studies centered on the cosmic microwave background (CMB) 
 and neutral hydrogen.\n\nhttps://indico.itp.ac.cn/event/417/contributions/
 2926/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2926/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Updated Constraints on Infrared Cutoff Models and Implications for
  CMB-BAO Tension
DTSTART;VALUE=DATE-TIME:20261107T073000Z
DTEND;VALUE=DATE-TIME:20261107T080000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2954@indico.itp.ac.cn
DESCRIPTION:Speakers: Ujjwal Kumar Upadhyay (The Institute of Mathematical
  Sciences)\nThe nearly scale-invariant primordial power spectrum provides 
 the standard initial conditions for cosmological perturbations. However\, 
 the largest observable scales remain only weakly constrained by current CM
 B measurements\, leaving open the possibility of deviations from scale inv
 ariance\, such as an infrared (IR) cutoff in the primordial spectrum. This
  possibility is further motivated by the persistence of large-scale CMB an
 omalies\, most notably the low quadrupole power. Recently\, IR cutoff scen
 arios have attracted renewed attention due to their potential interplay wi
 th reionisation features\, which can partially alleviate the emerging CMB
 –BAO discrepancy within the $\\Lambda$CDM framework following recent DES
 I observations. In this talk\, I will discuss our recent work where we rev
 isited several broad classes of phenomenologically motivated IR cutoff mod
 els using parametrised forms of the primordial power spectrum. I will pres
 ent updated constraints on IR cutoff scenarios from recent CMB observation
 s\, discuss their implications for the CMB–BAO discrepancy\, and comment
  on the status of large-scale CMB anomalies from a Bayesian perspective of
  anomaly statistics.\n\nhttps://indico.itp.ac.cn/event/417/contributions/2
 954/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2954/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Can Distance Duality Violation Save Late-time Solutions to the Hub
 ble Tension?
DTSTART;VALUE=DATE-TIME:20261107T070000Z
DTEND;VALUE=DATE-TIME:20261107T073000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2960@indico.itp.ac.cn
DESCRIPTION:Speakers: Yashi Tiwari (Institute of Theoretical Physics\, Chi
 nese Academy of Sciences)\nThe discrepancy between early- and late-Univers
 e determinations of the Hubble constant may point to physics beyond ΛCDM 
 or to unaccounted-for systematics. Numerous late-time modifications to the
  expansion history have been proposed to alleviate this discrepancy\, with
  limited success. Recent works have shown that\, when the sound-horizon an
 d supernova calibrations are held fixed\,any purely late-time resolution r
 equires a violation of the cosmic distance duality relation (CDDR). Recast
 ing the tension in the $r_d–M_B$ plane\, we show explicitly that distanc
 e duality\, together with BAO and uncalibrated supernova data and a fixed 
 sound-horizon calibration\, determines $H_0$ independently of the late-tim
 e expansion history. We then test the viability of the required CDDR viola
 tion by separately constraining reciprocity violation and photon number no
 n-conservation\, deriving a new constraint on reciprocity-violating distor
 tions of angular-diameter distances from BAO and cosmic-chronometer data. 
 Combining this result with existing photon-number-conservation constraints
 \, we find that the level of distance-duality violation needed to resolve 
 the tension is strongly disfavoured by current data. We therefore conclude
  that\, for fixed sound-horizon and supernova calibrations\, no modificati
 on confined to the late-time expansion history—even one violating distan
 ce duality—can resolve the Hubble tension\, pointing instead toward earl
 y-Universe physics or unresolved local systematics.\n\nhttps://indico.itp.
 ac.cn/event/417/contributions/2960/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2960/
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BEGIN:VEVENT
SUMMARY:Modified gravity and the cosmological tensions
DTSTART;VALUE=DATE-TIME:20261107T060000Z
DTEND;VALUE=DATE-TIME:20261107T063000Z
DTSTAMP;VALUE=DATE-TIME:20261023T102222Z
UID:indico-contribution-650-2949@indico.itp.ac.cn
DESCRIPTION:Speakers: Gen Ye (University of Chinese Academy of Sciences)\n
 Cosmological tensions are one of the central topics of modern cosmology. T
 he most prominent is the Hubble tension in which the measured expansion ra
 te of the Universe from distance ladder is more than $5 \\sigma$ larger th
 an that predicted by $\\Lambda$CDM based on CMB. Recently\, BAO observatio
 n from DESI also reports a $2 - 3 \\sigma$ tension with $\\Lambda$CDM whic
 h might point to evolving dark energy. In this talk I will discuss our rec
 ent research on the possible gravitational origin of these cosmological te
 nsions. Starting from model independent reconstruction technique\, we foun
 d that the DESI BAO observation can be well explained by non-minimal coupl
 ing between gravity and matter. Further study shows that the same non-mini
 mal coupled gravity can also naturally explain the Hubble tension\, hintin
 g a common gravitational origin of the two major cosmological tensions.\n\
 nhttps://indico.itp.ac.cn/event/417/contributions/2949/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2949/
END:VEVENT
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