Hep-ph

S. K. Agarwalla, IoP, Bhubaneswar
Title: New Opportunities at Future Long-Baseline Experiments
Abstract:

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S. Ansarifard, IPM
Title: A glimpse on two Higgs doublet models at forward experiments
Abstract:
The (g − 2)μ anomaly indicates that the second generation of leptons should have new interactions beyond the standard model. The high flux of ν and ν ̄ at the forward μμ experiments such as FASERν and SND@LHC makes them suitable setups to search for new interactions of the second generation leptons. In this talk, I introduce a model in which the second generation left-handed leptons couple to a new right-handed neutrino, N, and a new Higgs doublet which also couples to the quarks. The scattering of high energy νμ off nuclei can produce N. Discovering even a single such event can be a harbinger to look for the spectacular signals of the new Higgs doublet production at the LHC. I discuss the possibility of explaining the (g − 2)μ anomaly by adding more generations of N which will lead to chain decays of N and multiple leptons with distinct signals both at forward experiments and at the CMS and ATLAS detectors. Finally, I show that by adding a new light singlet scalar mixed with the neutral component of the new Higgs doublet the statistics of the data sample can be dramatically increased. 

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K. Azizi, Tehran U.
Title: Some recent developments in hadron physics
Abstract:
On 22 March 2021 the LHCb Collaboration at CERN announced serious Lepton flavor universality violation (LFUV) at some hadronic channels, like B-->K l^+l^-, up to 3.1 standard deviations from the standard model (SM) predictions. However, very recently, the LHCb reported a relatively small deviations from the SM theory expectations in  B-->K_s l^+l^- &  B-->K^* l^+l^- channels. I will review these results and introduce some new physics  scenarios beyond the SM to explain the LFUV in the channels that the violation is sizable. Then, I will discuss the recently discovered long-lived doubly charmed tetraquark T_cc and show our predictions on its mass and other properties that help us fix its nature and quantum numbers.

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N. Bernal, Antonio Narino U.
Title: Dark Matter in the Time of Primordial Black Holes
Abstract:
The evaporation of primordial black holes (PBH) with masses ranging from ~10^-1 to ~10^9 g could have generated the whole observed dark matter (DM) relic density, or at least have had a strong impact on the DM genesis. Here we will review several possibilities beyond the simplest paradigm, like: i) the effect of self-interactions for DM radiated by PBHs, ii) the interplay with a second DM production mechanism, like freeze-out or freeze-in, iii) and the unavoidable gravitational production. Additionally, for very light DM as in the case of QCD axions of axion-like particles, we will see that iv) even if PBHs cannot emit the whole axion cold dark matter abundance through Hawking radiation, they can have a strong impact on the dark matter produced via the misalignment mechanism.

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D. Cerdeno, Autonoma U.
Title: Light mediators in the neutrino sector: a new playground for direct detection experiments
Abstract:
Direct (dark matter) detection experiments have become extremely sensitive instruments, to the point that they will soon be affected by a new background source: solar neutrinos. This can be seen as an opportunity to study new physics in the neutrino sector, associated with light mediators. In this talk I will present two interesting examples. In the first one, I will argue that future direct detection experiments will be able to test the gauged U(1) Lmu-Ltau solution to the muon anomalous magnetic moment. In a second example, I will show that a recent reevaluation of supernova constraints (based on the neutrino diffusion time) allows for a large increase of the so-called neutrino floor.

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F. Hajkarim, Padua U.
Title: Production of Hot Axions in the Early Universe
Abstract:
We study the thermal production of axions over different scales especially around the QCD and electroweak phase transitions in the early universe. We focus on the most motivated axion models i.e. KSVZ and DFSZ including their UV completion regimes and investigate how the thermal history can influence on the production rate of hot axion as dark radiation assuming different axion decay constants. This can lead to predictions for the future measurements of the cosmic microwave background by experiments like CMB-S4.

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N. Khan, IPM
Title: FIMP Dark Matter, Neutrino mass and mixing angles in the Extended Higgs Triplet Model
Abstract:
We perform an exclusive study on the Feebly Interacting Massive Particle (FIMP)  dark matter candidate in an extended hyperchargeless ($Y=0$) Higgs triplet model. The additional neutral $Z_2$-odd singlet fermion plays the role of dark matter with support from two other vector-like fermion doublets. The mixing between the neutral component of a doublet and singlet fermions controls the current relic density through the Freeze-in mechanism, whereas the additional doublet fermion helps to get the neutrino mass and mixing angles. We obtain a broad region of the parameter spaces satisfying the current relic density and neutrino mass and mixing angles.

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J. Kopp, Mainz U.
Title: The Neutrino Magnetic Moment Portal?
Abstract:
We discuss neutrino magnetic moments as a way of constraining physics beyond the Standard Model. In fact, new physics at the TeV scale can easily generate observable neutrino magnetic moments - we discuss in particular possible connections to models aiming to solve the flavor anomalies. We then highlight the multitude of ways of probing neutrino magnetic moments, in particular using direct dark matter detection experiments (which are sensitive to neutrino magnetic moments because of the predicted modifications to the solar neutrino scattering rate), stellar cooling, and cosmological constraints from BBN and from the CMB. Looking into the future, we also mention possible constraints from a future Galactic supernova explosion, and from observations of high-energy astrophysical neutrinos.

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N. Mahmoudi, Lyon U.
Title: Implications of B anomalies for new physics

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S. Palomares-Ruiz, IFIC, Valencia
Title: Dark matter evaporation from celestial bodies
Abstract:
Scatterings of galactic dark matter (DM) particles with the constituents of celestial bodies could result in their accumulation within these objects and could give rise to observable effects. Nevertheless, the finite temperature of the medium sets a minimum mass, the evaporation mass, that DM particles must have in order to remain trapped. DM particles below this mass are very likely to scatter to speeds higher than the escape velocity, so they would be kicked out of the capturing object and escape. In this talk, I will describe the calculation of the DM evaporation mass for all spherical celestial bodies in hydrostatic equilibrium and I will illustrate the critical importance of the exponential tail of the evaporation rate. This has not always been appreciated in some recent works, which have suggested searches of DM particles too light to remain captured and to have observable effects. 

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S. Shakeri, Isfahan U. of Tech.
Title: The Role of Sterile Neutrinos in Recent Observed Anomalies
Abstract:
In this talk, I will present an effective model for the sterile neutrinos where  three sterile neutrinos couple to SM fermions and gauge bosons via the SM gauge symmetric four-fermion interactions. I will show that the sterile neutrinos with masses around 90 keV and specific effective coupling can explain the XENON1T anomaly preserving DM astrophysical and cosmological constraints. I point out that the presence of three right-handed sterile neutrino allows to obtain correct dark matter relic density by the late entropy production due to late decay of heavier right-handed neutrinos. Besides, I will discuss the possibility of explaining different anomalies in other experiments such as muon g-2 and MiniBooNe experiment. Our model also offers some new distinctive features which may potentially produce observable signals in the sensitivity range of the next generation of XENON detectors such as XENONnT, LZ and DARWIN.

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Z. Tabrizi, Northwestern University
Title: EFT at FASERv: An experiment to probe them all
Abstract:
We will discuss how to systematically study physics beyond the standard model (BSM) in the neutrino experiments within the Standard Model Effective Field Theory (SMEFT) framework. In this way, the analysis of the data can capture large classes of models, where the new degrees of freedom have masses well above the relevant energy of the experiment. Moreover, it allows us to compare several experiments in a unified framework and in a systematic way. Our proposed approach could be applied to several short- and long baseline neutrino experiments. We will show the results of this approach at the FASERv experiment, which will be soon installed 480 m downstream of the ATLAS interaction point. For some coupling structures, we find that these neutrino detectors will be able to constrain interactions that are almost three orders of magnitude weaker than the Standard Model weak interactions, implying that they will be indirectly probing new physics at the 10 TeV scale.

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S. Trojanowski,Copernicus Ctr.
Title:  Beyond the Standard Model physics case of far-forward searches at the LHC
Abstract:
During the upcoming Run 3, a new experimental program will be initiated at the LHC in its far-forward region. It will focus on the search for new light particles and on studying interactions of high-energy neutrinos. This is foreseen to be extended towards further future in the proposed Forward Physics Facility. In my talk, I will review the beyond the Standard Model physics case of this program. This includes, e.g., searches for sub-GeV unstable species, the possibility of directly detecting dark matter scatterings at the LHC, as well as probing non-standard neutrino interactions.

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Hep-th

H. Adami, BIMSA, Beijing

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G. Barnich, ULB
Title: Massless scalar partition functions on flat backgrounds, Eisenstein series and modular invariance in higher dimensions.
Abstract:
The problem of black hole entropy leads one to study of gauge systems in the presence of boundaries, and then also massless scalars with periodic boundary conditions. We show that the partition function of a massless scalar on the Euclidean spacetime manifold $\mathbb R^{d-q}times \mathbb T^{q+1}$ is expressed in terms of an SL$(q+1)$ Eisenstein series. Implications for modular invariance in higher dmensions are discussed. Trace and harmonic anomalies in the case of $\mathbb T^{d+1}$ are worked out and shown to originate from a zero mode. 

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F. Benini, SISSA
Title: Factorization and global symmetries in holography
Abstract:
There exist low-dimensional models of holography in which the bulk gravitational theory is dual to an ensemble average of boundary quantum field theories (as opposed to a single theory). In the case of three-dimensional gravitational theories based on topological field theories, we draw a connection between the ensemble averaging (and the lack of factorization of the partition function) and the presence of global symmetries. Once the global symmetries are removed (by a suitable gauging procedure), the gravitational theory behaves as a unitary quantum system.

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S. Deger, Bogazici, Istanbul
Title: Third Way Consistent Gauge Theories
Abstract: In this talk I will give an overview of the "third way consistent" gauge theories. The field equations of such models do not come from variation of a local action without additional fields, yet their equations of motion are still on-shell consistent. The first such example was found in 3-dimensions which is a massive Yang-Mills theory. After briefly introducing
this model, I will describe its N=1 supersymmetric extension. Then, I will explain the construction of interacting (d-2)-form theories in d-dimensions with this property and discuss some generalizations and open problems.

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L. Donnay, TUW, Vienna 

D. Grumiller, TUW, Vienna
Title: Generalized dilaton gravity in 2d
Abstract:
Generalized dilaton gravity in 2d is the most general consistent deformation of the Jackiw-Teitelboim model that maintains local Lorentz invariance. The action is generically not power-counting renormalizable, thus going beyond the class of models typically studied. As example, I focus on a specific family of models that describe black holes asymptoting to AdS in the UV and to dS in the IR.

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A. Mollabashi, Yukawa Inst.
Title: Entanglement Dynamics in Lifshitz Theories: Slow Modes Take the Main Role
Abstract:

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A. Seraj, ULB

M. Serone, SISSA 

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M. Taghiloo, IASBS, Zanjan 
Title: Symmetries at Null Boundaries: 3-dimensional gravity
Abstract:
Gauge transformations are usually viewed as redundancies in the description of gauge theories and the physical observables must be gauge invariant. This should be revisited in presence of boundaries where a part of gauge transformations to which there are non vanishing surface charge associated, can become physical "non-proper" gauge transformations. One can use these surface charges to label different points of the solution phase space. Here we consider Einstein gravity in presence of a given null boundary. We construct the maximal solution-phase space, find its symmetries and calculate the associated surface charges. Surface charges and their algebra depend on the slicing in solution phase space. We discuss the implications of change of slicing different aspects of solution-phase space, from integrability to algebra of surface charges.

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A.H. Tajdini, UCSB

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B. Tekin, METU, Ankara
Title: How does 2+1 dimensional massive gravity avoid anomalous dispersion?
Abstract:
In a vacuum with an odd dimensional space-like dimensions, a wave pulse does not suffer dispersion if all frequencies propagate at the same speed; and hence the Huygens' principle is not violated. But for a spacetime with  an even number of spacelike dimensions, the vacuum is
dispersive even if the wave speed is independent of the frequency. This is called anomalous dispersion and it is a major hindrance to sharp communication. The rumbling of thunder is an example to this. 2+1 dimensional gravity has been studied a lot in the literature but in general there is dispersion in this theory in a vacuum. Here we show how a particular theory in de Sitter spacetime is dispersion-free. We also show that 2+1 dimensional de Sitter spacetime
can be relevant to hyperbolic metamaterials: they might provide an example of dS/CFT correspondence.

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M. Vahidinia, IASBS, Zanjan
Title: Revisiting Black Hole Temperature in Horndeski Gravity
Abstract:
In contrast to the usual theories of gravity, there are certain Horendeski's gravities that Wald's entropy is not consistent with the first law of black hole thermodynamics. For these theories, the speed of propagation of gravitons and photons are different. It means that gravitons propagate on an effective metric. We show that this effective metric modifies our notion about the surface gravity and hence black hole temperature. Using this modified temperature and the solution phase space method, we calculate an unambiguous expression for entropy that is consistent with the first law.

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Cosmology

A. Abolhasani, Sharif. U. of T.
Title: A systematic approach to the cosmological correlators in the presence of the derivative interactions
Abstract:

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M. Amin, Rice U.

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M. Asgari, U. of Edinburgh
Title: Cosmology with the Kilo Degree Survey
Abstract:

The Kilo Degree Survey (KiDS) is a purpose-built gravitational lensing survey with high quality images and a wide photometric coverage, resulting in very high fidelity data. In this talk I will show the latest results from the cosmic shear analysis of 1000 square degrees of data from KiDS and its combination with spectroscopic galaxy surveys.  Adopting a flat Lambda-CDM model we obtain results that are in 3 sigma tension with the Planck legacy survey estimates of
S_8 = sigma_8 (Ω_m/0.3)^0.5. I will show that our analysis is robust to a number of measurement and modelling systematics. Finally I will focus on constraints on a selection of alternative models and discuss the implications of the observed tension.

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S. Baghram, Sharif. U. of T.

Title: Investigating the cosmic web with one-point and crossing statistics

Abstact:

The large scale structure (LSS) of the cosmos is a vast arena to study the cosmological models. The data from observations and simulations show that the LSS is structured like a cosmic web. In this talk, I will introduce the concept of 1-point statistics and crossing statistics in the context of excursion set theory. Then, I will discuss that how these two frameworks are used to study the cosmic web. The idea of merger history and specific length in the distribution of dark matter halos will be discussed as specific probes for cosmological models.

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C. Byrnes, Sussex U.
Title: Primordial black holes: A potential LIGO-Virgo, pulsar timing array and QCD connection
Abstract:
Although black holes can be the remnants of dead stars, it is also possible that some are primordial. Such primordial black holes are the unique dark matter candidate which is not a new type of particle, and they could also explain some of the unexpected properties of the black hole mergers that LIGO and Virgo have detected. I will summarise the evidence and (fine-tuning) challenges behind this claim. There is interesting coincidence of scales between the LIGO-Virgo events, the Chandrasekhar limit and the horizon mass during the QCD transition in the early universe, and the wavelength of gravitational waves on which NANOGrav may (potentially) have detected a stochastic gravitational wave background.

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E. Colgain, Sogang U.
Title: Is the Hubble constant a constant?

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E. Dimastrogiovanni, Groningen U.  

J. T. Firouzjaee, Kh. Nasir T. U.

D. Grin, Haverford College
Title: Ultra-light axions and CMB anisotropies from degree to arcminute scales
Abstract:
Ultra-light axions are a well-motivated candidate for dark matter and dark energy, motivated both by considerations from high-energy theory and observational challenges to the Lambda CDM cosmological paradigm. We will summarize the motivation to consider such a dark-sector component,  and explore empirical  consequences, ranging from the primary anisotropies of the CMB to late-time secondary anisotropies imprinted by gravitational lensing and Compton scattering in galaxy clusters, to local precision measurements. We will explore the potential of upcoming experimental efforts to critically test the ultra-light dark-sector parameter space.

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S. von Hausegger, Oxford University
Title: Testing the Cosmological Principle with Distant Galaxies

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B. Melcher, Northeastern U
Title: Alternative Thermal Histories and Dark Matter
Abstract:
Beyond Standard Model physics generically predicts the existence of a variety of dark sectors. The presence thereof can affect the thermal history of the universe, which can leave observable imprints on various cosmological observables. We discuss these issues in generality, then look at an example of a dark matter production mechanism that induces an early matter dominated era.

M. Zarei, Isfahan U. of T.
Title: Non-Markovian open quantum system approach to the early universe
Abstract:
In this talk, we review the application of the non-Markovian quantum Boltzmann equation (QBE) in CMB and GWs physics. Using this equation we study the microscopic influence of a cosmic environment on a system of cosmic background photons or stochastic gravitational waves. We apply the non-Markovian QBE to study the damping of gravitational waves propagating in a medium consisting of decoupled ultra-relativistic neutrinos. It is shown that, in contrast to intensity and linear polarization that are damped, the circular polarization (V-mode) of the gravitational wave (if present) is amplified by propagating through such a medium. We will also discuss the decoherence induced by squeezed stochastic GWs and show that one can derive the decoherence damping time using non-Markovian open quantum system approach. 

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Special talk  by
Azadeh Fattahi, Durham U.
Title: Recent findings of Gaia on Galactic accretion history and its implications for dark matter direct detection
Abstract:
Thanks to the Gaia mission, we have uncovered a major component of the Galactic inner halo characterised by its high anisotropy, named “Gaia-Enceladus-Sausage”. This component is thought to be the debris from the accretion of a massive dwarf galaxies and a significant event in the history of the Milky Way. Using cosmological hydrodynamical simulations of Milky Way like halos, I will discuss built up of stellar halos and what this particular event implies for the kinematics of Galactic dark matter halo and the implications for dark matter detection experiment.

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Planery Speakers

K. Freese, U. of Texas, Austin
Title: Dark Matter in the Universe
Abstract:
The nature of the dark matter in the Universe is among the longest outstanding problems in all of modern physics. The bulk of the mass in the Universe is thought to consist of a new (as yet unknown) dark matter particle. I'll begin by discussing the evidence for the existence of dark matter in galaxies, and then show how it fits into a big picture of the Universe containing 5% atoms, 25% dark matter, and 70% dark energy.  Neutrinos constitute ½% of the content of the Universe and we are nailing down their properties with cosmological data.  Leading candidates for the dark matter are Weakly Interacting Massive Particles (WIMPs), axions, sterile neutrinos, primordial black holes, and light dark matter. WIMPs are a generic class of particles that are electrically neutral and do not participate in strong interactions, yet have weak-scale interactions with ordinary matter. I’ll discuss multiple approaches to experimental searches for WIMPS: at CERN in Geneva, in underground laboratories, with astrophysical searches, looking for tracks in ancient rocks.  I’ll tell you about our novel idea of Dark Stars, early stars powered by dark matter heating, and the possibility that the upcoming James Webb Space Telescope could find them.  Current results from the DAMA experiment keep getting more puzzling and the interpretation in terms of dark matter will be tested soon.  I’ll end by showing how stellar kinematics data from the GAIA satellite provides a new approach to test the nature of Dark Matter.

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J. Garcia-Bellido, IFT, Madrid
Title: Covariant formulation of non-equilibrium thermodynamics in General Relativity: Cosmic Acceleration from First Principles
Abstract:
We construct a generally-covariant formulation of non-equilibrium thermodynamics in General Relativity. We find covariant entropic forces arising from gradients of the entropy density, and a corresponding non-conservation of the energy momentum tensor in terms of these forces. We also provide a Hamiltonian formulation of General Relativity in the context of non-equilibrium phenomena and write the Raychaudhuri equations for a congruence of geodesics. We find that a fluid satisfying the strong energy condition could avoid collapse for a positive and sufficiently large entropic-force contribution. We then study the forces arising from gradients of the bulk entropy of hydrodynamical matter, as well as the entropy of boundary terms in the action, like those of black hole horizons. We apply the covariant formulation of non-equilibrium thermodynamics to the expanding universe and obtain the modified Friedmann equations, with an extra term corresponding to an entropic force satisfying the second law of thermodynamics. General relativistic entropic acceleration theory may explain the present cosmic acceleration from first principles without the need of introducing a cosmological constant. Following the covariant formulation of non-equilibrium phenomena in the context of a homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker (FLRW) metric, we find that the growth of entropy associated with the causal horizon of our universe (inside a finite bubble in eternal inflation) induces an acceleration that is essentially indistinguishable from that of ΛCDM, except for a slightly larger present rate of expansion compared to what would be expected from the CMB in ΛCDM, possibly solving the so-called H0 tension. The matter content of the universe is unchanged and the coincidence problem is resolved since it is the growth of the causal horizon of matter that introduces this new relativistic entropic force. The cosmological constant is made unnecessary and the future hypersurface is Minkowsky rather than de Sitter.

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M. Guica, Nordita and Saclay
Title: Irrelevant current-current deformations and holography
Abstract:
In 2016, Smirnov and Zamolodchikov constructed a set of surprisingly tractable irrelevant deformations of two-dimensional quantum field theories, which appear to produce UV-complete QFTs, albeit non-local. I will review some of the remarkable properties of these theories, as well as their various interesting applications, in particular to holography. Finally, I will argue these QFTs are best thought of as non-local versions of two-dimensional CFTs.

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M. Kamionkowski, Johns Hopkins U.
Title: The Hubble tension and the early Universe
Abstract:
The value of the cosmic expansion rate (the Hubble constant) inferred from observations of supernovae disagree with those inferred from measurements of the cosmic microwave background.  Easy explanations for this discrepancy have been elusive, but the past few years attention has turned to the possibility that a modification to early-Universe physics may be required.  I will discuss a solution to this "Hubble tension" that involves the introduction of a new component of matter, “early dark energy,” as well as other related ideas.

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Y. Mambrini, IJCLab, Orsay
Title: (Dark) matter production in the post-inflationary phase

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S. Mathur, Ohio State U.

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S. Pascoli, Bologna U.
Title: Developments in neutrino physics
Abstract:
In the past twenty years, the discovery of neutrino oscillations has changed our understanding of neutrinos. We now know that they have mass and they mix and, thanks to a broad experimental programme, a rather precise picture has emerged of their properties. The explanation of neutrino masses implies new physics beyond the Standard Model (BSM) which is still to be unveiled. In this talk, I will briefly review the current knowledge of neutrino properties, highlighting the still open questions, with emphasis on the nature of neutrinos, their masses and leptonic CP violation. I will then discuss recent developments in sterile neutrinos searches, including the very recent MicroBooNE results, and their possible implications in terms of possible hints in favour of a dark sector that couples to neutrinos.

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E. Silverstein, Stanford U.
Title: De Sitter Microstates from a solvable generalization of the T-Tbar deformation.
Abstract:
The finite value of the de Sitter entropy suggests a formulation of its observer patch as a system with a finite-dimensional Hilbert space. We show that a new version of the solvable $T\bar T + \Lambda_2$ deformation of a seed holographic CFT gives such a theory at the level of physics accessible in pure gravity. This is sufficient to capture both the finite entropy -- the microstate count - along with a subleading logarithmic correction at large c -- and the bulk dS geometry (but it does not capture model-dependent aspects of bulk matter fields, which requires additional ingredients.

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T. Takayanagi, Kyoto U.
Title: Holography and Quantum Information
Abstract:
The idea of holography in string theory provides a simple geometric computation of entanglement entropy. This generalizes the well-known Bekenstein-Hawking formula of black hole entropy and strongly suggests that a gravitational spacetime consists of many bits of quantum entanglement. After we give a brief review of this field, I will report various results on a recently introduced quantity called pseudo entropy, which generalizes the entanglement entropy and has a manifest gravity dual.

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