BEGIN:VCALENDAR VERSION:2.0 PRODID:-//LAPTh - ECPv6.15.17//NONSGML v1.0//EN CALSCALE:GREGORIAN METHOD:PUBLISH X-WR-CALNAME:LAPTh X-ORIGINAL-URL:https://www.lapth.cnrs.fr X-WR-CALDESC:Évènements pour LAPTh REFRESH-INTERVAL;VALUE=DURATION:PT1H X-Robots-Tag:noindex X-PUBLISHED-TTL:PT1H BEGIN:VTIMEZONE TZID:Europe/Paris BEGIN:DAYLIGHT TZOFFSETFROM:+0100 TZOFFSETTO:+0200 TZNAME:CEST DTSTART:20210328T010000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:+0200 TZOFFSETTO:+0100 TZNAME:CET DTSTART:20211031T010000 END:STANDARD BEGIN:DAYLIGHT TZOFFSETFROM:+0100 TZOFFSETTO:+0200 TZNAME:CEST DTSTART:20220327T010000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:+0200 TZOFFSETTO:+0100 TZNAME:CET DTSTART:20221030T010000 END:STANDARD BEGIN:DAYLIGHT TZOFFSETFROM:+0100 TZOFFSETTO:+0200 TZNAME:CEST DTSTART:20230326T010000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:+0200 TZOFFSETTO:+0100 TZNAME:CET DTSTART:20231029T010000 END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20220602T110000 DTEND;TZID=Europe/Paris:20220602T120000 DTSTAMP:20260403T211733 CREATED:20220620T163002Z LAST-MODIFIED:20220620T163002Z UID:7827-1654167600-1654171200@www.lapth.cnrs.fr SUMMARY:Imprints of axion-like particles in photon spectra from galaxy clusters DESCRIPTION: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. URL:https://www.lapth.cnrs.fr/event/imprints-of-axion-like-particles-in-photon-spectra-from-galaxy-clusters/ CATEGORIES:Weekly seminars END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20220609T110000 DTEND;TZID=Europe/Paris:20220609T120000 DTSTAMP:20260403T211733 CREATED:20220620T163000Z LAST-MODIFIED:20220620T163000Z UID:7823-1654772400-1654776000@www.lapth.cnrs.fr SUMMARY:Higgs alignment and the top quark DESCRIPTION:In 1976\, S. Weinberg and his student\, E. Gildener (GW)\, proposed\nmulti-Higgs models of electroweak symmetry breaking which are clas-\nsically scale-invariant. If this scale invariance is spontaneously broken\,\nthe Higgs boson is the resulting massless dilaton and\, of all the model’s\nscalars\, its couplings to gauge bosons and fermions are exactly as in\nthe one-Higgs-doublet Standard Model of Weinberg’s 1967 “Model of\nLeptons”. That is\, this Higgs boson is aligned. But\, since the clas-\nsical Higgs potential has an infinitely long flat minimum\, there is no\nfixed mass scale — i.e.\, no fixed VEV — at this level and no concrete\nmeaning to this statement.\nThis scale invariance is explicitly broken by the renormalization\nscale Λ in the one-loop approximation of the Coleman-E. Weinberg\neffective potential\, the Higgs boson boson gets mass\, and its VEV\nv is fixed by its relation to Λ. GW assigned its value to be v =\n2−1/4G−1/2\nF = 246 GeV. Now Higgs alignment means something\, but\nis it preserved in one-loop order\, i.e.\, is it natural? And what about\nhigher orders?\nIn this talk\, I will summarize the above in a two-Higgs-doublet\nmodel of the GW mechanism\, emphasizing the surprisingly low masses\nof the model’s BSM Higgs and the role of the top quark in Higgs\nalignment\, update the important experimental consequences of this\nalignment — stressing the futility of most ATLAS and CMS searches\nfor BSM Higgses\, and preview the extension of these results to two-\nloops.\nThis work was started in 2019 with ́Eric Pilon and extended in 2020\nwith Estia Eichten. The two-loop extension is done with Eichten. URL:https://www.lapth.cnrs.fr/event/higgs-alignment-and-the-top-quark/ CATEGORIES:Weekly seminars END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20220613T140000 DTEND;TZID=Europe/Paris:20220613T150000 DTSTAMP:20260403T211733 CREATED:20220620T163009Z LAST-MODIFIED:20220620T163009Z UID:7854-1655128800-1655132400@www.lapth.cnrs.fr SUMMARY:Primordial black holes from supercooled first-order phase transition DESCRIPTION: 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.   URL:https://www.lapth.cnrs.fr/event/primordial-black-holes-from-supercooled-first-order-phase-transition/ CATEGORIES:Weekly seminars END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20220614T110000 DTEND;TZID=Europe/Paris:20220614T120000 DTSTAMP:20260403T211733 CREATED:20220620T162949Z LAST-MODIFIED:20220620T162949Z UID:7797-1655204400-1655208000@www.lapth.cnrs.fr SUMMARY:[Journal Club] A novel theoretical approach to $R(D^{(*)})$ through the Dispersive Matrix method DESCRIPTION:Abstract: \nThe 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. \n  \nZoom link: \nhttps://cnrs.zoom.us/j/91049381574?pwd=TDZyU3NqT0k4MFk3cUMvc0JuOURCdz09 URL:https://www.lapth.cnrs.fr/event/journal-club-a-novel-theoretical-approach-to-rd-through-the-dispersive-matrix-method/ CATEGORIES:Upcoming Journal Club END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20220616T110000 DTEND;TZID=Europe/Paris:20220616T120000 DTSTAMP:20260403T211733 CREATED:20220620T163002Z LAST-MODIFIED:20220620T163002Z UID:7828-1655377200-1655380800@www.lapth.cnrs.fr SUMMARY:Intelligent Explorations of the String Theory Landscape [Remote talk] DESCRIPTION: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. URL:https://www.lapth.cnrs.fr/event/intelligent-explorations-of-the-string-theory-landscape-remote-talk/ CATEGORIES:Weekly seminars END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20220621T110000 DTEND;TZID=Europe/Paris:20220621T120000 DTSTAMP:20260403T211733 CREATED:20220620T162950Z LAST-MODIFIED:20220620T163036Z UID:7799-1655809200-1655812800@www.lapth.cnrs.fr SUMMARY:[Journal Club] Bootstrapping Pions at Large N DESCRIPTION: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.\nFinally\, 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. \n  URL:https://www.lapth.cnrs.fr/event/journal-club-bootstrapping-pions-at-large-n/ CATEGORIES:Upcoming Journal Club END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20220623T110000 DTEND;TZID=Europe/Paris:20220623T120000 DTSTAMP:20260403T211733 CREATED:20220620T163003Z LAST-MODIFIED:20220620T163038Z UID:7831-1655982000-1655985600@www.lapth.cnrs.fr SUMMARY:Star forming galaxies as cosmic ray factories: a multimessenger view DESCRIPTION:Star forming galaxies (SFGs) are powerful factories of high-energy cosmic rays.\nTheir 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.\n \nThe 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.\nI will illustrate the main features and the impact of calorimetry on the spectral energy distribution of these galaxies.\nIn 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.\n \nDespite of the extreme conditions expected to be found in the interstellar medium of SBGs\, accelerators of sub-galactic scale\nsuch as supernova remnants or star clusters are unlikely to overcome the PeV range.  \nOn 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.\nI will discuss a physical model describing particle acceleration and transport in these galactic wind bubbles.\nFinally\, I will conclude presenting the multi-messenger potential of SBGs and their wind bubbles in terms of gamma rays\, neutrinos and escaping cosmic rays. URL:https://www.lapth.cnrs.fr/event/star-forming-galaxies-as-cosmic-ray-factories-a-multimessenger-view/ CATEGORIES:Weekly seminars END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20220628T110000 DTEND;TZID=Europe/Paris:20220628T120000 DTSTAMP:20260403T211733 CREATED:20220620T162948Z LAST-MODIFIED:20220620T163036Z UID:7796-1656414000-1656417600@www.lapth.cnrs.fr SUMMARY:[Journal Club] Björn Herrmann DESCRIPTION:Abstract: \n  \nZoom link: \nhttps://cnrs.zoom.us/j/91049381574?pwd=TDZyU3NqT0k4MFk3cUMvc0JuOURCdz09 URL:https://www.lapth.cnrs.fr/event/journal-club-bjorn-herrmann/ CATEGORIES:Upcoming Journal Club END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20220630T110000 DTEND;TZID=Europe/Paris:20220630T120000 DTSTAMP:20260403T211733 CREATED:20220620T163001Z LAST-MODIFIED:20220620T163039Z UID:7826-1656586800-1656590400@www.lapth.cnrs.fr SUMMARY:Presentations doctorants DESCRIPTION: URL:https://www.lapth.cnrs.fr/event/presentations-doctorants-2/ CATEGORIES:Weekly seminars END:VEVENT END:VCALENDAR