[Journal Club] About Long-Lived Particles
2022-04-12 11:00 - 12:00 (Europe/Paris)
Abstract:

Zoom link:
https://cnrs.zoom.us/j/91049381574?pwd=[REDACTED]

Berry phases, wormholes and factorization in AdS/CFT [Remote talk]
2022-04-21 11:00 - 12:00 (Europe/Paris)
Within the AdS/CFT correspondence, the entanglement properties of the
CFT are related to wormholes in the dual gravity theory. This gives rise
to questions about the factorisation properties of the Hilbert spaces on
both sides of the correspondence. We review these issues and show how
the Berry phase, a geometrical phase encoding information about
topology, may be used to reveal similarities between the Hilbert space
structure on both sides of the correspondence. Mathematical concepts
such as coadjoint orbits play an important role. In addition to its
relevance for quantum gravity, this analysis also suggests how to
experimentally realise the Berry phase and its relation to entanglement
in table-top experiments involving photons or electrons. This provides a
new example for relations between very different branches of physics
that follow from the AdS/CFT correspondence and its generalisations.

[Journal Club] Right-handed neutrinos, TeV scale BSM neutral Higgs boson, and FIMP dark matter in an EFT framework
2022-05-03 11:00 - 12:00 (Europe/Paris)
Abstract:
We consider an effective field theory framework with three Standard Model (SM) gauge singlet right-handed neutrinos and an additional SM gauge singlet scalar field. The framework generates eV masses of light neutrinos via the seesaw mechanism and accommodates a feebly interacting massive particle (FIMP) as a dark matter candidate.
Two of the gauge singlet neutrinos participate in neutrino mass generation, while the third gauge singlet neutrino is a FIMP dark matter. We explore the correlation between the vev (vacuum expectation value) of the gauge singlet scalar field which translates as the mass of the BSM Higgs, and the mass of dark matter, which arises due to the relic density constraint. We perform a collider analysis to explore the discovery prospect of the TeV scale, BSM Higgs, through its difatjet signature, at a future pp collider, FCC-hh.

[Journal Club] Absorption or Emission of Solitons
2022-05-10 11:00 - 12:00 (Europe/Paris)
Abstract:

CMB, LSS and the distance ladder: cosmic discordance? [Remote talk]
2022-05-12 11:00 - 12:00 (Europe/Paris)
The Lambda-cold-dark-matter (LCDM) model has established itself as a fantastic (yet parametric) concordance model able to adjust a wide variety of cosmological observables — CMB, BBN, Large Scale Structure (LSS) & SN1a most notably. However as the precision of the data has increased over the past few years, a number of predictions of the LCDM model are challenged by recent observations.
First and foremost, the infamous ‘Hubble tension’ is a strong mismatch between the value of the Hubble constant measured using the classical distance ladder method and that inferred from the ΛCDM model. Second, the ‘S8 tension’ is a longstanding discrepancy between the determination of the amplitude of matter fluctuations on a 8 Mpc/h scale by galaxy (weak lensing) surveys and its prediction within the LCDM model.
After a brief review of the various measurements (and some potential short-comings), I will discuss potential implications that such measurements could have. I will argue that current data favor the possibility that our Universe has undergone anomalous expansion just before recombination and present an overview of the most promising models (early dark energy, additional dark radiation component and new neutrino properties), and their current limitations. I will present guidelines to resolve these tensions simultaneously and suggest what it might take to establish a new `concordance model’ beyond LCDM.

The Tadpole Problem [Remote talk]
2022-05-18 16:00 - 17:00 (Europe/Paris)
I will discuss string theory compactifications where a large number of moduli is stabilized by fluxes. I will first present a conjecture which rules out the stabilization of all complex-structure moduli in F-theory at a generic point in moduli space by fluxes that satisfy the tadpole cancellation condition. Evidence for this conjecture comes from studying K3xK3 compactifications using evolutionary algorithms.
Subsequently, I will discuss obstructions on flux compactifications coming from AdS/CFT holography. Here, I will argue that it is not possible to obtain KKLT-like AdS vacua with very small cosmological constants by putting a bound on the central charge of the dual theory. These results have important consequences for the construction of de Sitter vacua in string theory.

AnLy Strings & Fields 2nd in-person Meeting
2022-05-19 08:00 - 20:00 (Europe/Paris)
This is a meeting on topics related to string and field theory, between members of nearby institutions:

IP2I (CNRS, UCBL), Lyon

LAPTh (CNRS, USMB), Annecy

LPENSL (CNRS, ENSL), Lyon

More information can be found on the AnLy webpage.
For this second edition, the meeting will take place in IP2I, Lyon, on the 19/05/22. Talks will happen in room 429 (4th floor) and salle des réunions (3rd floor).

Travel
Options between Lyon and Annecy are train (or train + bus), Flixbus, or car (and car-sharing).
Information on how to access the IP2I can be found on this page.

Lunch
Several lunch options are possible close to the IP2I (canteen, restaurant, etc.).

Internet
Eduroam is available at the IP2I.

Presentation stagiaires suite
2022-05-24 10:45 - 11:00 (Europe/Paris)

Three-dimensional flux vacua from Type II supergravities
2022-05-24 11:00 - 12:00 (Europe/Paris)
We discuss flux compactifications of Type IIA supergravity on G2 spaces with smeared O2/O6-planes down to three dimensions. We start by presenting the setup of allowed fluxes, the internal geometry, the equations of motion and after compactification we achieve N=1 AdS3 vacua with scale that can be parametrically decoupled from the KK modes. The solutions we find are at weak coupling and large volume regime while the moduli are fully stabilized at the classical level. Next, utilizing the exact equations of motion including varying warp factor and dilaton we evaluate the backreaction of O6-planes. Using the appropriate flux scaling we show that the corrections to the various background fields are subleading when going from smeared to localized sources and we find the distances from the loci where the smeared approximation can be trusted. We discuss the possibility for de Sitter uplift as well as results of similar compactifications in Type IIB on curved internal G2 spaces.

[Journal Club] A fundamental plane relation for the gamma-ray luminosity of pulsars
2022-05-31 11:00 - 12:00 (Europe/Paris)
Abstract:
https://arxiv.org/abs/2203.13276
https://iopscience.iop.org/article/10.3847/2041-8213/ab3e0a (1904.01765)

Imprints of axion-like particles in photon spectra from galaxy clusters
2022-06-02 11:00 - 12:00 (Europe/Paris)
Modulations of X-ray spectra from extragalactic sources might provide a signature of photons converting into axion-like particles (ALPs) when traversing a region with a large-scale magnetic field. A crucial unknown in these searches is the structure of the magnetic field considered. In this talk I discuss the impact of realistic models of the magnetic field on ALP-photon oscillations.

Higgs alignment and the top quark
2022-06-09 11:00 - 12:00 (Europe/Paris)
In 1976, S. Weinberg and his student, E. Gildener (GW), proposed
multi-Higgs models of electroweak symmetry breaking which are clas-
sically scale-invariant. If this scale invariance is spontaneously broken,
the Higgs boson is the resulting massless dilaton and, of all the model’s
scalars, its couplings to gauge bosons and fermions are exactly as in
the one-Higgs-doublet Standard Model of Weinberg’s 1967 “Model of
Leptons”. That is, this Higgs boson is aligned. But, since the clas-
sical Higgs potential has an infinitely long flat minimum, there is no
fixed mass scale — i.e., no fixed VEV — at this level and no concrete
meaning to this statement.
This scale invariance is explicitly broken by the renormalization
scale Λ in the one-loop approximation of the Coleman-E. Weinberg
effective potential, the Higgs boson boson gets mass, and its VEV
v is fixed by its relation to Λ. GW assigned its value to be v =
2−1/4G−1/2
F = 246 GeV. Now Higgs alignment means something, but
is it preserved in one-loop order, i.e., is it natural? And what about
higher orders?
In this talk, I will summarize the above in a two-Higgs-doublet
model of the GW mechanism, emphasizing the surprisingly low masses
of the model’s BSM Higgs and the role of the top quark in Higgs
alignment, update the important experimental consequences of this
alignment — stressing the futility of most ATLAS and CMS searches
for BSM Higgses, and preview the extension of these results to two-
loops.
This work was started in 2019 with ́Eric Pilon and extended in 2020
with Estia Eichten. The two-loop extension is done with Eichten.

Primordial black holes from supercooled first-order phase transition
2022-06-13 14:00 - 15:00 (Europe/Paris)
Cosmological first-order phase transition are said strongly supercooled when the nucleation temperature is much smaller than the critical temperature. They are typical of potentials which feature nearly scale-invariance, for which the bounce action decreases only logarithmically with time. The phase transition takes place slowly and the probability distribution of bubble nucleation time is maximally spread. Hubble patches which get percolated later than the average are hotter than the background after reheating and potentially collapse into black holes. We discuss the formation of primordial black hole by supercooled first-order phase transitions and we present two classes of particle physics models predicting such transitions.

[Journal Club] A novel theoretical approach to $R(D^{(*)})$ through the Dispersive Matrix method
2022-06-14 11:00 - 12:00 (Europe/Paris)
Abstract:
The ratios $R(D^{(*)})$ are defined as the $tau/mu$ ratio of the branching fractions of exclusive semileptonic $B to D^{(*)}$ decays. They are a powerful test of Lepton Flavour Universality, one of the pillars of the SM, and are determined by the hadronic Form Factors (FFs) describing the $B to D^{(*)}$ decays. Through the novel Dispersive Matrix (DM) approach, we describe these FFs without assumptions on their functional dependence on the momentum transfer. The DM method is based on the non-perturbative determination of the dispersive bounds due to unitarity and analyticity, and allows to determine in a model-independent way the FFs in the full kinematical range, starting from existing Lattice QCD data which are available only at large momentum transfer. Using the unitarity bands of the FFs, which are thus independent of the experimental determinations of the differential decay widths, we compute new fully-theoretical expectations of the anomalies. Our results read $R(D) = 0.296(8)$ and $R(D^*) = 0.275(8)$, each of which is compatible with the corresponding world average of the measurements at the $sim 1.3 sigma$ level. The origin of the discrepancy between the DM estimates and the HFLAV SM predictions will be also discussed.

Zoom link:
https://cnrs.zoom.us/j/91049381574?pwd=[REDACTED]

Intelligent Explorations of the String Theory Landscape [Remote talk]
2022-06-16 11:00 - 12:00 (Europe/Paris)
The goal of identifying the Standard Model of particle physics and its extensions within string theory has been one of the principal driving forces in string phenomenology. Recently, the incorporation of artificial intelligence in string theory and certain theoretical advancements have brought to light unexpected solutions to mathematical hurdles that have so far hindered progress in this direction. In this talk I will focus on model building efforts in the context of the E8 × E8 heterotic string compactified on smooth Calabi-Yau threefolds and discuss several areas in which machine learning is expected to make a difference.

[Journal Club] Bootstrapping Pions at Large N
2022-06-21 11:00 - 12:00 (Europe/Paris)
Abstract: For this journal club meeting I will comment on a recent paper by Albert and Rastelli (https://arxiv.org/abs/2203.11950) in which they apply modern S-matrix bootstrap techniques to the old problem of solving QCD in the large N limit. In particular, they derive universal bounds for the EFT of massless pions and find that the allowed region for large N theories compatible with unitarity, causality and analiticity of the S-matrix exhibits a sharp kink, suggesting the possibility that large N QCD might sit on it in a similar way as the 3D Ising model.
Finally, I will make some remarks on the similitudes and differences between this case and that of obtaining bounds for the gravitational S-matrix, and on the difficulties in extending this ideas to the latter.

Star forming galaxies as cosmic ray factories: a multimessenger view
2022-06-23 11:00 - 12:00 (Europe/Paris)
Star forming galaxies (SFGs) are powerful factories of high-energy cosmic rays.
Their star formation rate (SFR) is a key physical property characterizing both the total energy budget and the transport conditions of such particle populations. Tight correlations are in fact observed between the SFR and the non-thermal radio and gamma-ray luminosity of several SFGs. I will discuss the nature of such correlations focusing on the physical implications on the particle transport.

The most active SFGs are known as starburst galaxies (SBGs). These objects are unique environments for cosmic rays since they might be able to confine most of their injected particles. Such a calorimetric scenario is of great interest for the production of hadronic byproducts such as non-thermal radiation and high-energy neutrinos.
I will illustrate the main features and the impact of calorimetry on the spectral energy distribution of these galaxies.
In addition, since SBGs are also inferred to be highly numerous at cosmological distances, I will discuss their possible contribution to the diffuse fluxes of gamma rays and neutrinos observed by Fermi-LAT and IceCube respectively.

Despite of the extreme conditions expected to be found in the interstellar medium of SBGs, accelerators of sub-galactic scale
such as supernova remnants or star clusters are unlikely to overcome the PeV range.
On the other hand, the enhanced rate of supernovae characterizing SBGs can launch powerful winds with bubble structures where particles can be efficiently accelerated at higher energies.
I will discuss a physical model describing particle acceleration and transport in these galactic wind bubbles.
Finally, I will conclude presenting the multi-messenger potential of SBGs and their wind bubbles in terms of gamma rays, neutrinos and escaping cosmic rays.

[Journal Club] Björn Herrmann
2022-06-28 11:00 - 12:00 (Europe/Paris)

Presentations doctorants
2022-06-30 11:00 - 12:00, 2022-07-07 11:00 - 12:00 (Europe/Paris)

RAQIS 22
2022-08-29 09:00 - 2022-09-02 17:00 (Europe/Paris)
Recent Advances in Quantum Integrable Systems

Newtonian regime in a spherical or hyperbolic universe and consequences for the role of spatial curvature in cosmology
2022-09-08 11:00 - 12:00 (Europe/Paris)
The standard model of cosmology currently allows for three types of geometries for our Universe (Euclidean, spherical or hyperbolic), each of these types corresponding to a set of different (multiconnected)-topologies. Among these geometries, Newton’s theory of gravity is only defined on the Euclidean one. Still, extending the validity of this theory to the two other cases, with the aim that this should constitute the limit of a relativistic theory of gravity, could provide a strong theoretical tool to probe large scale effects of global topology.
The first part of this presentation will aim at constructing such a theory, using the concept of Galilean structures. We will see that it allows to quantify the effects of topology on the gravitational potential and structure formation.
In the second part, I will show that Einstein’s equation is necessarily incompatible with such an extension of Newton’s theory. However, as a physical hypothesis for our Universe, if we require the Newtonian regime to exist regardless of the global geometry and topology, then Einstein’s equation should be modified. This can be done by adding a “topological term’’ arising from the introduction of a second non-dynamical metric in the theory. The main consequence of this modification is that the expansion law of a homogeneous and isotropic solution no longer features the spatial curvature (i.e. $Omega = 1, forall Omega_k$). I will argue that this result gives a simple solution to the flatness problem, and asks for a reevaluation of the spatial curvature from current cosmological data.

Alpine Strings 2022
2022-10-14 09:00 - 18:30 (Europe/Paris)
This 1-day workshop aims at gathering in Annecy the local string and quantum field theory community for fruitful exchanges on active research topics. Those include:

Bootstrap

Swampland program and string phenomenology
Supergravity and Exceptional Field Theories

Participating institutions are mainly LPENS (Lyon), IP2I (Lyon), LAPTh (Annecy), CERN (Meyrin), UNIGE (Geneva) and EPFL (Lausanne). Young researchers are particularly encouraged to participate.
A preliminary list of speakers includes:

TBA

Travel
Annecy can be reached by train (SNCF, SBB), bus (including B272, or Flixbus), car (including car-sharing Blablacar).
Detailed information on how to access the LAPTh can be found on this page; in particular, buses connecting the station and the LAPTh are indicated.

Lunch and dinner
There is no lunch option close to the LAPTh (no shop, canteen, etc.). A vegetarian lunch can be provided on both days. Please indicate your interest when registering.
A pizza dinner will be proposed on the 14th October.

Accomodation
A hotel for the night 13-14th October will be proposed when registering.

Internet
Eduroam is available at LAPTh. Another possibility is to get a guest access when you arrive.

This workshop is funded thanks to the AAP USMB “Bootstrapping the Swampland”. It is part of the AnLy activities.
Local organisers: D. Andriot, P. Tourkine.

News from the Universe: A Trio of Intriguing Developments in Astrophysics and Cosmology
2023-05-09 09:00 - 10:00 UTC | Auditorium (LAPTh)
Speakers: Christopher Eckner (CNRS, LAPTh)
Abstract:I will present three recent papers advancing our understanding of astrophysics and cosmology. The covered papers are:I) arXiv:2304.0607: “The Image of the M87 Black Hole Reconstructed with PRIMO” A crisper image of the supermassive black hole of M87 with machine learningII) arXiv:2304.09895: “Anomalies in Gravitational-Lensed Images Revealing Einstein Rings Modulated by Wavelike Dark Matter” Using strong gravitational lensing to discriminate between fuzzy and WIMP-like dark matter III) arXiv:2304.10934: “A Cross-correlation Study between IceCube Neutrino Events and the Fermi Unresolved Gamma-ray Sky” Where do all the very-high-energy neutrinos detected by IceCube come from?
https://indico.in2p3.fr/event/29748/

DM indirect searches with cosmic-ray antiparticles
2023-05-11 09:00 - 10:00 UTC | Auditorium (LAPTh)
Speakers: Pedro de la Torre Luque (Stockholm University)
The creation of antiparticles in the Galaxy has been discussed as a potential signal of exotic production mechanisms such as primordial black hole evaporation or dark matter decay/annihilation, in addition to the more conventional production from cosmic-ray (CR) interactions. Recent CR detectors have provided very accurate measurements on the spectra of antiprotons and positrons that we use to search for evidence of new physics. In addition, the exciting first measurements of the flux of anti-nuclei can be achievable in a few years.In this talk, I discuss the uncertainties related to the modelling of these antiparticles and show state-of-art predictions of their spectra. We will also talk about recent dark matter constraints from antiprotons and positrons and discuss the expected fluxes of anti-deuteron and anti-helium from global analyses of different CR observables in view of the first tentative detection of anti-nuclei events by the AMS-02 collaboration. Finally, if time allows it, I will discuss an ongoing study where we use CR data to place constrains of DM candidates beyond WIMPs (e.g. ALPs, sterile neutrinos, …) coupling with electrons.
https://indico.in2p3.fr/event/29312/

Entanglement and separability of Rokhsar-Kivelson and resonating valence-bond states
2023-05-16 12:00 - 13:00 UTC | Auditorium (LAPTh)
Speakers: Gilles Parez (CRM, Montréal)
Entanglement and separability are two opposite yet intertwined notions in quantum mechanics. A quantum state is said to be entangled if it is not separable, and vice versa. Quantifying how entangled two subsystems are remains a challenging problem, which has led to important insights in the context of quantum many-body systems. In this talk, I will discuss entanglement and separability of dimer Rokhsar-Kivelson (RK) states and resonating valence-bond (RVB) states. For dimer RK states on general tilable graphs, we prove the exact separability of the reduced density matrix of two or more disconnected subsystems, implying the absence of entanglement between the subsystems. For RVB states, we show separability for disconnected systems up to exponentially small terms in the distance d between the subsystems. We argue that separability does hold in the scaling limit, even for arbitrarily small ratio d/L, where L is the characteristic size of the subsystems. Our results hold irrespective of the underlying graph (which include square and triangular lattices), and hence suggest that separability (up to exponentially small terms) between disjoint regions is a universal feature of RVB states. In the case of adjacent subsystems for the RK states, we derive exact results for the logarithmic negativity in terms of partition functions of the underlying statistical model, and recover the known result for the Rényi-1/2 entropy in the limit of complementary subsystems.
https://indico.in2p3.fr/event/29487/

[AnLy] Gerben Venken
2023-05-17 14:00 - 15:00 UTC | Online seminar
Speakers: Gerben Venken (U. Heidelberg)
Abstract: Link: ZoomAnLy: https://sites.google.com/view/anlystringsandfields
https://indico.in2p3.fr/event/29869/

French Strings Meeting 2023
2023-05-23 10:00 - 2023-05-25 15:00 UTC | LAPTh
This meeting will gather the France-based community working in string and quantum field theory for three days of scientific exchanges on current developments in these research areas. The workshop will take place at LAPTh, Annecy, from Tuesday 23rd May at 2pm till Thursday 25th at around 2pm. The detailed program can be found here. Talks are by invitation. Review talks will be given by:Yifei He (LPENS, Paris)Severin Lüst (L2C, Montpellier)Eric Perlmutter (IPhT, Saclay)Speakers list:Nejc Ceplak (IPhT, Saclay)Yegor Goncharov (IDP, Tours)Nafiz Ishtiaque (IHES, Bures-sur-Yvette)Taro Kimura (IMB, Dijon)Bruno Le Floch (LPTHE, Paris)Sucheta Majumdar (LPENS, Lyon)Paul Marconnet (IP2I, Lyon)Blagoje Oblak (CPhT, Palaiseau)Valentin Reys (IPhT, Saclay)Mikel Sanchez-Garitaonandia (CPhT, Palaiseau)George Tringas (LAPTh, Annecy)Alexander Tumanov (LPENS, Paris)This meeting is an activity of IRN:QFS, the International Research Network on Quantum Fields and Strings. Previous editions of similar workshops include:French kick-off meeting of IRN:QFS (Tours, 2021)Théorie des Cordes en France (Paris, 2015) Registration: can be done here. It will close on April 23rd. In case of high attendance, preference will be given to the members of institutes covered by the network IRN:QFS in France. Accommodation: will be covered by the IRN:QFS network for 2 nights (23-25/05), in the limit of 50 participants. The hotel is Best Western International, 19 avenue du Rhône, Annecy. Travel: Annecy can be reached by train (SNCF), bus (Flixbus) or car (including car-sharing Blablacar). Detailed information on how to access the LAPTh can be found on this page. Buses connecting the station and the LAPTh are indicated. Travel costs are to be covered by participants. Lunch and Dinner: Lunches, as well as a workshop dinner, will be offered. Lunches will be provided at LAPTh. The workshop dinner will take place at the Brasserie de l’Impérial. To reach the dinner restaurant as a group, we will leave LAPTh and catch the Bus 1 at Campus, stop at Montremont and walk along Avenue de France. Organizing Committee: David Andriot, Benjamin Basso, Xavier Bekaert, Dmitrii Chicherin, Laurent Gallot, Ruben Minasian, Boris Pioline, Andrea Puhm, Henning Samtleben, Piotr Tourkine. Funding: IRN:QFS, LAPTh, FRIF, CPTGA
https://indico.in2p3.fr/event/28620/

[Journal Club] Pasquale Serpico
2023-05-30 09:00 - 10:00 UTC | Petit Amphi (LAPTh)
Speakers: Pasquale Serpico (LAPTh, Annecy-le-vieux)
Abstract:
https://indico.in2p3.fr/event/29749/

[AnLy] Solving 3d Gravity with Virasoro TQFT
2023-05-31 14:00 - 15:00 UTC | Online seminar
Speakers: Lorenz Eberhardt (Princeton, IAS)
Abstract: I will explain a proposal which relates three-dimensional quantum gravity in AdS3 to a particular 3d TQFT that we refer to as “Virasoro TQFT’’. This relation gives a precise meaning to the standard folklore that pure 3d gravity is related to two copies of SL(2,R) Chern-Simons theory. I will discuss that replacing SL(2,R) Chern-Simons theory by Virasoro TQFT solves several known problems in the correspondence. The relation provides a computationally useful tool to study partition functions of 3d gravity. The talk is based on work with Scott Collier and Mengyang Zhang.Link: ZoomAnLy: https://sites.google.com/view/anlystringsandfields
https://indico.in2p3.fr/event/30080/
