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Justine Serrano (Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France)20/10/2025, 09:15General
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Emilie Passemar20/10/2025, 09:25
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Gino Isidori (University of Zurich (CH))20/10/2025, 10:05
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Zbigniew Andrzej Was (Polish Academy of Sciences (PL))20/10/2025, 11:15
Present day high statistic tau lepton experimental samples, require continuous revision of simulation precision. This is especially important for multi-dimensional signatures. That is in partiucular important in context of anomalous couplings.
Also, because evolution of software environments, completion of programs migration to C++ as well as study of new effects become of ever greater...
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Alberto Lusiani (Scuola Normale Superiore and INFN, sezione di Pisa)20/10/2025, 11:45
In the Tau section of the HFLAV 2023 report (arXiv:2411.18639 [hep-ex]) we present an improved global fit of the tau branching fractions and new combinations of tau lepton-flavour-violating (LFV) upper limits. The branching fraction fit includes recent measurements and furthermore since this report features nuisance fit parameters. The HFLAV fit is now...
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Santiago Paz Castro (Universitat de València)20/10/2025, 12:05
Semileptonic τ decays mainly proceed via interactions between charged lepton and quark currents. The hadronization of the quark current is intrinsically nonperturbative and generally cannot be addressed analytically. In this work, we propose using symmetry arguments alone to construct clean angular observables, which, within the Standard Model and in the absence of long-distance...
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Ce Zhang (University of Liverpool)20/10/2025, 12:25
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Marco Buonsante (Universita e INFN, Bari (IT))20/10/2025, 14:00
Tau leptons play a central role in the search for physics beyond the Standard Model at the LHC. This talk presents recent results from the CMS Collaboration on both direct searches for new physics with taus and precision tests of lepton flavor universality. Novel reconstruction techniques, targeting taus with low transverse momentum and those produced at displaced vertices, open sensitivity to...
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Minerva Maheshwari (University of Cambridge (GB))20/10/2025, 14:20
Many theories beyond the Standard Model predict new phenomena, such as leptoquarks, vector like leptons, supersymmetry, new scalars or heavy leptons, in final states with isolated taus reconstructed using standard techniques. Searches for new physics with such signatures, produced either resonantly or non-resonantly, are performed using the ATLAS experiment at the LHC. The most recent results...
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Andrea Cardini (Universidad de Oviedo)20/10/2025, 14:40
Tau leptons play a crucial role in studies of the Higgs boson and searches for Beyond the Standard Model physics at the present LHC and in its high luminosity upgrade. This talk presents the latest advancements in the reconstruction and identification of hadronic decays of tau leptons at the CMS experiment, both at the online and offline levels. The tau identification algorithm deployed for...
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Adrian Salvador Salas 🥝 (Tel Aviv University (IL))20/10/2025, 15:00
Many extensions of the Standard Model predict new phenomena like beyond-the-Standard-Model couplings to the Higgs boson, charged Higgs, Heavy neutral lepton, supersymmetry, among others. In this talk, the latest searches latest from the ATLAS experiment will be reported, with emphasis on the final states using special tau reconstruction techniques like merged or boosted tau topologies as well...
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Marco Del Vecchio (Sapienza Universita e INFN, Roma I (IT))20/10/2025, 15:20
The H->tau tau decay mode has a relatively high BR and good S/B ratio when considering advanced techniques to reconstruct and identify tau leptons in all possible decay modes. This enables the search of rare process, as non-resonant di-Higgs production, where one of the Higgs boson decays to ditaus. Possible channels involve H->gamma gamma, H->bb, associated with the H->tau tau decay. This...
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Dr Marcela Garcia (KEK)20/10/2025, 16:10
The rates of lepton-flavour violation in charged lepton decays are enhanced in many beyond-the-standard-model theories. During the first run of the Belle II experiment 365 fb$^{-1}$ of $e^{+}e^{-}$ collision data was collected at a centre-of-mass energy corresponding to the $\Upsilon(4S)$ resonance. This dataset contains around 340 million $e^{+}e^{-} \rightarrow \tau^{+}\tau^{-}$ events with...
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Gabriele Levati20/10/2025, 16:30
New physics scenarios addressing the flavor puzzle generally predict dominant interactions with fermions of the third generation. In this talk, I will discuss the prospects for probing light particles beyond the standard model — such as light vectors, scalars and axion-like particles — which possess dominant couplings to the tau lepton. In particular, I will focus on the possibility to...
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Arthur Thaller (INFN Roma3)20/10/2025, 16:50
The rates of lepton-flavour, lepton-number, and baryon-number violating $\tau$ decays are enhanced in many beyond-the-standard-model theories. The Belle and Belle II experiments have collected samples of $e^{+}e^{-}$ collision data containing a huge number of $e^{+}e^{-} \rightarrow \tau^{+}\tau^{-}$ events with constrained kinematics and low backgrounds, providing an ideal environment to...
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Julian Heeck20/10/2025, 17:10
I present a concise overview of tau flavor violation and the broad opportunities it offers, with a focus on non-standard decay channels and their underlying theoretical motivations.
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Dr Gerardin Antoine (CPT Marseille)21/10/2025, 09:00g-2
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Dr Estifa'a Zaid (University of Liverpool (GB)), Estifa'a Zaid (university of liverpool)21/10/2025, 09:40
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Dr Léonard POLAT (LPNHE-Paris/IJClab-Orsay)21/10/2025, 10:10
A measurement of the key cross section e+e- to pi+pi- for hadronic vacuum polarization (HVP)is presented with the full BABAR statistics using a new method not relying on particle ID to separate pions ans muons, therefore independent from the 2009 analysis. This result should play an important role to clarify the presently rather confused situation where large discrepancies are observed between...
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Joël Gogniat (University of Bern)21/10/2025, 11:00
Despite being a highly sensitive probe for physics beyond the Standard Model (BSM), the anomalous magnetic moment of the tau lepton $a_\tau$ remains significantly less explored than those of other leptons. This talk presents a promising path to measure $a_\tau$ with a precision of $10^-5$, a level crucial for imposing meaningful constraints on BSM theories. Achieving this precision...
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Dr Savannah Clawson21/10/2025, 11:20
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.110.092016
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Eslam Shokr (University of Zurich (CH)))21/10/2025, 11:40LHC
We will present the latest limits on the anomalous magnetic moment (g – 2) of the tau lepton at CMS. These are obtained from photon-induced processes in heavy-ion collisions, or in proton-proton collisions.
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John Andrew Hallford (Deutsches Elektronen-Synchrotron (DE))21/10/2025, 12:00
In ultra-relativistic heavy-ion collisions, high rates of $\gamma\gamma$ processes occur through the interaction of the large electromagnetic fields of the heavy nuclei. For large impact parameters between the nuclei, i.e. interaction distances larger than the nuclei's radii, the di-photon interaction can be the only one taking place, leading to very clean signatures in the detector. One of...
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Lucas Morethes Mansur21/10/2025, 14:00
The extraction of the QCD coupling, $\alpha_s$, from hadronic tau decays relies on experimental determinations of the relevant inclusive spectral functions. In this work, we produce a new inclusive vector-isovector spectral function combining information from several experiments. We obtain contributions from the dominant decay modes, $\pi^-\pi^0$, $2\pi^-\pi^+\pi^0$, and $\pi^-3\pi^0$, adding...
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Kim Maltman (York University (Canada))21/10/2025, 14:20
We discuss recent results leading to a new understanding of one of the two
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main approaches to determining $\alpha_s$ from finite-energy sum rule analyses of non-strange hadronic $\tau$ decay data. This approach involves fits to sets of differently weighted spectral integrals with a single common upper endpoint, $s=s_0$, in which several in-principle-present, higher-dimension condensate... -
Prof. ANTONIO PICH (IFIC, University of Valencia - CSIC)21/10/2025, 14:40
The inclusive hadronic width of the tau lepton can be rigorously analysed with quantum-field-theory techniques. Precise experimental measurements of the invariant-mass distribution of the final hadrons make possible to perform an accurate low-energy determination of the strong coupling and extract useful information about non-perturbative QCD parameters. An overview of the current status will...
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Pablo Roig Garcés21/10/2025, 15:20
In case there are tensor interactions beyond the SM in the low-energy EFT Lagrangian, their interference with the SM V-A currents yields a contribution for tau decays into three or more mesons [as we noted in Phys.Rev.D 106 (2022) 9, 096016] that cannot be included in the famous structure functions introduced by Kühn and Mirkes (KM) in their seminal 1992 paper [Z.Phys.C 56 (1992) 661-672]. We...
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Giuseppe Gagliardi21/10/2025, 15:40
The inclusive hadronic decays of the $\tau$ lepton provide an alternative avenue for determining the CKM matrix elements $V_{ud}$ and $V_{us}$. In this talk, I will present recent results from the ETM Collaboration for the inclusive hadronic $\tau$ decay rate, obtained in $N_{f}=2+1+1$ QCD using the novel HLT method. This approach circumvents the well-known inverse Laplace transform problem...
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David d'Enterria (CERN)21/10/2025, 16:30
The bound state of two tau leptons, called ditauonium or true-tauonium $\mathcal{T}$, is the heaviest and also most compact QED atom, and remains unobserved to date. Its study has several motivations such as precisely extracting properties of the tau lepton, carrying out novel tests of SM and its basic CPT symmetries, and searching for BSM effects impacting the tau lepton. We will first...
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Luca Marzola (National Institute of Chemical Physics and Biophysics (EE))21/10/2025, 16:50
Quantum state tomography involves a series of measurements that provide complete information about the quantum state describing the system under investigation. In this presentation, I review the capabilities of this technique for studying the spin state of tau lepton pairs produced at current and future lepton colliders. The reconstruction of the quantum state describing these systems allows...
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Johan Andrés Colorado Caicedo21/10/2025, 17:10
The existence and unknown nature of dark matter motivates dark sector searches at accelerators. The Belle experiment has collected samples of $e^{+}e^{-}$ collision data containing a huge number of $e^{+}e^{-} \rightarrow \tau^{+}\tau^{-}$ events with constrained kinematics and low backgrounds, enabling several world-leading dark matter searches in the sub-GeV mass region. Using 800...
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Gabriel Lopez Castro21/10/2025, 17:30
The sensitivity of the rare eta-pion decay channel of the tau lepton to new physics (NP) is investigated in the framework of models that contain scalar interactions. The different sources of isospin breaking are included in the Standard Model contributions. Using the current upper limits on the branching ratio of this rare decay, combined with precise measurements of other allowed semileptonic...
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Dr Nejc Košnik (J. Stefan Institute, University of Ljubljana)22/10/2025, 09:00
I will review the current phenomenological status of B decays involving tau leptons in the final state and what is the interplay with broader class of processes involving tau.
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I will emphasize how tau decays grant us access into detailed structure of interactions in B physics. -
Patrizia De Simone (Istituto Nazionale Fisica Nucleare (IT))22/10/2025, 09:40
In the SM, the electroweak bosons couple to the three lepton families with the same strength having the only difference in their behaviour due to the difference in mass. The current measurements of the ratios of branching fractions for b-hadrons decaying into final states with different lepton flavours deviate of the order of 3 σ with respect to the Standar Model. This talk presents recent...
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Paul Feichtinger (Institut "Jožef Stefan")22/10/2025, 10:00
In this talk, we will review the latest Belle II results on b -> s tau tau decays and tests of lepton flavour universality in b -> c tau nu decays.
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Hanae Tilquin (Imperial College (GB))22/10/2025, 10:20
Several discrepant measurements have been observed by LHCb and other experiments in b→cτν decays over the past few years. If these are due to new physics beyond the Standard Model, several models suggest an associated large enhancement in the branching fractions of b→sττ decays. Such decays have not been observed yet, and the existing upper limits which have been set are several orders of...
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Riccardo Pilato (University of Liverpool (GB))22/10/2025, 11:00
The MUonE experiment at CERN aims to provide an independent measurement of the leading-order hadronic contribution to the muon g-2 ($a_{\mu}^\text{HVP}$), complementary to the existing ones. The innovative approach proposed by MUonE is based on the measurement of the hadronic contribution to the running of the QED coupling, which can be extracted from a precise measurement of the shape of the...
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Christoph Redmer22/10/2025, 11:20
Electromagnetic transition form factors of light mesons are important inputs to the calculations of the hadronic light-by-light scattering contribution to the Standard Model prediction of the anomalous magnetic moment of the muon. However, data in the relevant regions of momentum transfer are scarce. The BESIII experiment at the $e^+ e^-$ collider BEPCII has collected the world's largest data...
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Dr Zhiqing ZHANG (IJClab-Orsay)22/10/2025, 11:40
Tau data, especially the 2-pion spectral function, can be used to compute the HVP contribution to the SM muon g-2 prediction after correcting for isospin violations between tau and e+e-. These corrections are usually computed theoretically with uncertainties sometimes difficult to establish. We present here a data-based evaluation of the most critical correction to the charged-current pion...
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Martina Cottini (University of Bern)22/10/2025, 12:00
The hadronic $\tau$ decay, $\tau\rightarrow\pi\pi^0\nu_\tau$, provides an independent way to compute the HVP contribution to the muon $g-2$ Standard Model (SM) prediction, provided one is able to reliably evaluate the relevant isospin breaking (IB) corrections. I will present a dispersive approach to the evaluation of the IB corrections relating $\tau\rightarrow\pi\pi^0\nu_\tau$ to...
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Gabriel Lopez Castro22/10/2025, 12:20
We revisit the isospin-breaking corrections relating the e+e- hadronic cross section and the tau decay spectral function, focusing on the dipion channel, that gives the dominant contribution to the hadronic vacuum polarization piece of the muon g-2. We test different types of electromagnetic and weak form factors and show that both, the Gounaris-Sakurai and a dispersive-based approach,...
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Léo Borrel (California Institute of Technology)23/10/2025, 09:00
The Mu2e experiment will search for coherent neutrinoless conversion of a negative muon into an electron in the field of an aluminium nucleus. Observation of this process would be a signature of Charged Lepton Flavor Violation (CLFV), a Beyond the Standard Model (BSM) process predicted by various theories. Mu2e aims to improve the current limit by four orders of magnitude, reaching a single...
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Dr Marius Köppel (ETH Zurich)23/10/2025, 09:20
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William McNulty (Indiana University)23/10/2025, 09:40
Charged lepton flavor violation is a popular target in searches for new physics. We demonstrate how the search for violations of an accidental symmetry of the Standard Model can also be connected to the search for violations of more fundamental symmetries. Working in the Standard Model Extension, a Lorentz- and CPT-violating effective field theory, we investigate the conversion of a muon to...
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Thomas CLOUVEL23/10/2025, 10:00
Experiments on neutrino oscillations have demonstrated that lepton flavor can be violated for neutral leptons. However, no charged lepton flavor violation (cLFV) has yet been observed. The COMET experiment [1] aims to detect cLFV through a process involving new physics: the coherent, neutrinoless conversion of a muon bound to a nucleus into an electron (μ⁻ + N(Z,A) → e⁻ + N(Z,A)). The...
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Lorenzo Ferrari Barusso (Università di Genova, INFN Genova)23/10/2025, 10:20
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Steven Eulig (Harvard University and IceCube)23/10/2025, 11:10
Separating tracks from cascades in IceCube is critical for precision oscillation measurements and tau-appearance searches, yet sparse hit patterns at lower energies limit the reach of standard topology-based methods. We address this challenge with WavePID, a new variable engineered based on the timing profile of single-DOM waveforms at 5-100 GeV, inspired by earlier PID results in...
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David Jason Koskinen23/10/2025, 11:30
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Helena Almazan (Donostia International Physics Center (DIPC) (ES))23/10/2025, 11:50
Water Cherenkov detectors have demonstrated exceptional sensitivity in
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neutrino observation over the years. The Hyper-Kamiokande (Hyper-K),
the third generation of underground detectors in Japan, represents a
significant advancement in both sensitivity and scalability. Hyper-K will
act as the far detector for a long-baseline neutrino oscillation experiment
using the upgraded 1.3 MW J-PARC... -
Nicole Geißelbrecht (ECAP)23/10/2025, 12:10
The tau neutrino is one of the least well studied particles in the Standard Model, with an overall measured statistics of about 2000 events. KM3NeT/ORCA is a water Cherenkov detector currently under construction in the Mediterranean Sea that aims to determine the neutrino mass ordering. It is optimised for the detection of atmospheric neutrinos in the 1-100 GeV range. While the atmospheric...
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Dr Yuri Gornushkin23/10/2025, 12:30
The DsTau (NA65) experiment at CERN is designed to measure the inclusive differential cross-section for Ds meson production, followed by its decay into a tau lepton and tau neutrino, in proton–nucleus interactions. The DsTau detector, employing the nuclear emulsion technique, offers sub-micron spatial resolution, allowing for highly precise detection of short-lived particles such as charmed...
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Adrian DARRICAU23/10/2025, 14:00
We address the phenomenological impact of a well-motivated class of
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scotogenic models regarding flavour and electroweak precision observables. In particular, and for the case of a ``T1-2-A'' variant, we carry out a full computation of the next-to-leading order corrections to leptonic Higgs and $Z$-boson decays. In view of the evolution in the tension between theory and observation regarding... -
Maria Domenica Galati (Van Swinderen Institute, University of Groningen)23/10/2025, 14:20
In this talk we present the outcome of a stand-alone feasibility study using RapidSim simulation software that demonstrates that the Large Hadron Collider beauty (LHCb) experiment will be capable of observing the decays $B^+\rightarrow\tau^+\nu_{\tau}$ and $B_c^+\rightarrow\tau^+\nu_{\tau}$ using the data that is being collecting during Run 3 of the LHC. Our proposed analysis exploits the...
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Dr Petar Rados23/10/2025, 14:40
The Belle and Belle II experiments have collected a $1.1~\mathrm{ab}^{-1}$ sample of $e^+e^-$ collision data at centre-of-mass energies corresponding to the $\Upsilon(4S)$ resonances. The $\Upsilon(4S)$ resonance decays almost exclusively to $B\bar{B}$ pairs. Using these data, we search for lepton-flavour-violating decays $B\to K^{(*)}\tau \ell$. In addition, we present searches for...
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Giulia Frau (The University of Manchester (GB))23/10/2025, 15:00
Charged Lepton Flavour Violation (cLFV) is strongly suppressed in the Standard Model and therefore represents a sensitive probe for physics beyond it. Recently, the LHCb experiment has performed dedicated searches for cLFV, both in semileptonic b-hadron decays and in purely leptonic tau decays, placing competitive bounds on several decay modes. These results provide relevant constraints on a...
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Paolo Massarotti (University Federico II and INFN, Naples (IT))23/10/2025, 16:00Talk
The $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ decay is a golden mode for flavour physics. Its branching ratio is predicted with high precision by the Standard Model to be less than $10^{-10}$, and this decay mode is highly sensitive to indirect effects of new physics up to the highest mass scales. A new measurement of the $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ decay by the NA62 experiment at the...
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William McNulty23/10/2025, 16:20
Neutrino non-standard interactions (NSI) have been studied in a variety of contexts and suggested as a possible mechanism for resolving certain unexpected results in oscillation experiments. NSI may be generated in various ways and take a variety of forms. We focus on flavor-changing neutral current NSIs involving tau neutrinos. In simple scenarios in which these are generated by...
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David Jason Koskinen23/10/2025, 16:40
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Juliana Stachurska23/10/2025, 17:00
The IceCube Neutrino Observatory at the South Pole can detect neutrinos of all flavors well into the PeV energy range. Measuring the tau component and the overall flavor composition of astrophysical neutrinos is a powerful probe of cosmic particle accelerator mechanisms. However, due to the sparse light sensor layout and the relatively short tau decay length, tau neutrino identification in...
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Daniele Centanni (INFN Sezione di Napoli (IT))23/10/2025, 17:20
The SND@LHC experiment was designed to perform measurements with neutrinos produced at the LHC within the unexplored pseudo-rapidity range of 7.2 < 𝜂 < 8.6. Located 480 m downstream of IP1 in the unused TI18 tunnel, this compact and stand-alone experiment employs a hybrid detector system consisting of 800 kg of tungsten plates interleaved with emulsion and electronic trackers, complemented by...
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Mingyi Liu (University of Science and Technology of China)24/10/2025, 09:00
The super tau-charm facility proposed in China, is suppose to produce 3.5 billion tau pairs per year in the energy region of 4 to 5 GeV. Besides, the STCF covers the threshold of tau pairs. Based on thses samples, general topics are proposed at STCF, e.g., cLFV processes, $|V_{us}|$ measurements, alpha_s and tau mass measurements. Novel topics are proposed at well, e.g., tau atoms. In this...
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Alberto Lusiani (Scuola Normale Superiore and INFN, sezione di Pisa)24/10/2025, 09:30
We estimate the precision at FCC-ee on the measurements of the tau mass, lifetime, leptonic branching fractions, and on the searches for lepton-flavour-violating branching fractions $\tau \to \mu\gamma$ and $\tau \to 3\mu$. We compute the estimated precision on the lepton flavour universality tests, considering the 2nd-order QED radiative corrections and estimating the radiative corrections...
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Prof. Michael Roney (University of Victoria)24/10/2025, 10:00
Upgrading the SuperKEKB e+e− collider with polarized electron beams, the Chiral Belle project, provides new and unique opportunities for searches for new physics via precision electroweak and other measurements, including measurements involving the tau lepton.
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These include measurements the neutral current vector couplings via left-right asymmetry (ALR) measurements in annihilations to pairs... -
Laura Zani24/10/2025, 11:00General
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Joao Coelho (CNRS / APC - Paris)24/10/2025, 11:40
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Justine Serrano (Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France)24/10/2025, 12:20
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Michael Roney
We report a measurement of $R(D) = B(B\to D\tau\bar\nu_\tau)/B(B\to D\ell\bar\nu_\ell)$
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and $R(D^*) = B(B\to D^*\tau\bar\nu_\tau)/B(B\to D^*\ell\bar\nu_\ell)$, where $\ell$
refers to either an electron or muon. The dataset consists of
426 fb$^{-1}$ collected at the $\Upsilon(4S)$ resonance by the BABAR detector at the
PEP-II asymmetric storage ring collider. We select samples by... -
Vitalii Lisovskyi (EPFL (CH) and Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille (F))
This is to check the submission of proceedings linked to this abstract.
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