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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Search for resonances decaying to an anomalous jet and a Higgs boson in proton–proton collisions at $$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$
, The European Physical Journal C, Vol: 86<jats:title>Abstract</jats:title> <jats:p> This paper presents a search for new physics through the process where a massive particle, X, decays into a Higgs boson and a second particle, Y. The Higgs boson subsequently decays into a bottom quark–antiquark pair, which is reconstructed as a single large-radius jet. The decay products of Yare also assumed to produce a single large-radius jet. The identification of the Yparticle is enhanced by computing the anomaly score of its candidate jet using an autoencoder, which measures deviations from typical quark- or gluon-induced jets. This allows a simultaneous search for multiple Ydecay scenarios within a single analysis. In the main benchmark process, Yis a scalar particle that decays into a Wboson pair. Two other scalar Ydecay processes are also considered as benchmarks: decays to a light quark–antiquark pair, and decays to a top quark–antiquark pair. A fourth benchmark process considers Yas a hadronically decaying top quark, arising from the decay of a vector-like quark into a top quark and a Higgs boson. Data recorded by the CMS experiment at a center-of-mass energy of 13 <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\,\text {Te}\hspace{-.08em}\text {V}$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mspace/> <mml:mtext>Te</mml:mtext> <mml:mspace/> <mml:mtext>V</mml:mtext> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> in 2016–2018, correspond
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Journal articleOishi K, Aoki M, Kuribayashi S, et al., 2026,
Development of the Range Counter for the COMET Phase-α Experiment
, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Vol: 1082, ISSN: 0168-9002 -
Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
First Exclusive Reconstruction of the B^{*+}, B^{*0}, and B_{s}^{*0} Mesons and Precise Measurement of Their Masses.
, Phys Rev Lett, Vol: 136Using proton-proton collision data collected by the CMS experiment at sqrt[s]=13 TeV in 2016-2018, corresponding to an integrated luminosity of 140 fb^{-1}, the first full reconstruction of the three vector B meson states, B^{*+}, B^{*0}, and B_{s}^{*0}, is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be m(B^{*+})-m(B^{+})=45.277±0.039±0.027 MeV, m(B^{*0})-m(B^{0})=45.471±0.056±0.028 MeV, and m(B_{s}^{*0})-m(B_{s}^{0})=49.407±0.132±0.041 MeV, where the first uncertainties are statistical and the second are systematic. These results improve on the precision of previous measurements by an order of magnitude.
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Journal articleNakanishi F, Abe K, Abe S, et al., 2026,
First Associated Neutrino Search for a Failed Supernova Candidate with Super-Kamiokande
, The Astrophysical Journal Letters, Vol: 997, Pages: L9-L9, ISSN: 2041-8205<jats:title>Abstract</jats:title> <jats:p> In 2024, a failed supernova (SN) candidate, M31-2014-DS1, was reported in the Andromeda galaxy (M31), located at a distance of approximately 770 kpc. In this Letter, we search for neutrinos from this failed SN using data from Super-Kamiokande (SK). Based on the estimated time of black hole formation inferred from optical and infrared observations, we define a search window for neutrino events in the SK data. Using this window, we develop a dedicated analysis method for failed SNe and apply it to M31-2014-DS1, by conducting a cluster search using the timing and energy information of candidate events. No significant neutrino excess is observed within the search region. Consequently, we place an upper limit on the time-integrated electron antineutrino luminosity from M31-2014-DS1 and discuss its implications for various failed SN models and their neutrino emission characteristics. Despite the 18 MeV threshold adopted to suppress backgrounds, the search remains sufficiently sensitive to constrain the Shen-TM1 equation of state, in a more optimistic emission scenario with progenitor stars of 40 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> and relatively high mean electron-antineutrino energies of about 23.2 MeV, yielding a 90% confidence level upper limit of 1.76 × 10 <jats:sup>53</jats:sup> erg on the time-integrated electron antineutrino luminosity, moderately above the expected value of 1.35 × 10 <jats:sup>53</jats:sup> erg. </jats:p>
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Search for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>b</mml:mi> </mml:math> -hadron decays to long-lived particles in the CMS endcap muon detectors
, Physical Review D, Vol: 113, ISSN: 2470-0010<jats:p> A search for long-lived particles originating from the decay of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>b</a:mi> </a:math> hadrons produced in proton-proton collisions with a center-of-mass energy of 13 TeV at the LHC is presented. The analysis is performed on a dataset recorded in 2018, corresponding to an integrated luminosity of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mn>41.6</c:mn> <c:mtext> </c:mtext> <c:mtext> </c:mtext> <c:msup> <c:mi>fb</c:mi> <c:mrow> <c:mo>−</c:mo> <c:mn>1</c:mn> </c:mrow> </c:msup> </c:math> . Interactions of the long-lived particles in the CMS endcap muon system would create hadronic or electromagnetic showers, producing clusters of detector hits. Selected events contain at least one such high-multiplicity cluster in the muon endcaps and require the presence of a displaced muon. The most stringent upper limits to date on the branching fraction <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mi mathvariant="script">B</e:mi> <e:mo stretchy="false">(</e:mo> <e:mi>B</e:mi> <e:mo stretchy="false">→</e:mo> <e:mi>K</e:mi>
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026,
First Observation of CP Violation and Measurement of Polarization in B^{+}→ρ(770)^{0}K^{*}(892)^{+} Decays.
, Phys Rev Lett, Vol: 136An amplitude analysis of the B^{+}→(π^{+}π^{-})(K_{S}^{0}π^{+}) decay is performed in the mass regions 0.30<m_{π^{+}π^{-}}<1.10 GeV/c^{2} and 0.75<m_{K_{S}^{0}π^{+}}<1.20 GeV/c^{2}, using pp collision data recorded with the LHCb detector corresponding to an integrated luminosity of 9 fb^{-1}. The polarization fractions and CP asymmetries for B^{+}→ρ(770)^{0}K^{*}(892)^{+} decays are measured. Violation of the CP symmetry in the decay B^{+}→ρ(770)^{0}K^{*}(892)^{+} is observed for the first time, with a significance exceeding 9 standard deviations. The CP asymmetry is measured to be A_{CP}=0.507±0.062(stat)±0.024(syst) and the CP-averaged longitudinal polarization fraction of f_{L}=0.720±0.028(stat)±0.009(syst). The measurements help to shed light on the polarization puzzle of B mesons decaying to two vector mesons.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026,
Observation of B_{c}^{+}→Dh^{+}h^{-} Decays.
, Phys Rev Lett, Vol: 136Searches are presented for B_{c}^{+}→Dh^{+}h^{-} decays, where D is a charmed meson and h^{±} is a charged pion or kaon, using pp collision data collected by the LHCb experiment corresponding to an integrated luminosity of 9 fb^{-1}. The decays B_{c}^{+}→D^{+}K^{+}π^{-}, B_{c}^{+}→D^{*+}K^{+}π^{-}, and B_{c}^{+}→D_{s}^{+}K^{+}K^{-} are observed for the first time. Their branching fractions, expressed as ratios relative to that of the B_{c}^{+}→B_{s}^{0}π^{+} decay, are determined to be R(B_{c}^{+}→D^{+}K^{+}π^{-})=(1.96±0.23±0.08±0.10)×10^{-3}, R(B_{c}^{+}→D^{*+}K^{+}π^{-})=(3.67±0.55±0.24±0.20)×10^{-3}, R(B_{c}^{+}→D_{s}^{+}K^{+}K^{-})=(1.61±0.35±0.13±0.07)×10^{-3}, where the first uncertainty is statistical, the second is systematic, and the third is due to the limited precision on the D-meson branching fractions. The decay channels proceed primarily through excited K^{0} or D^{0} resonances or ϕ mesons, and open a new avenue for studies of charge-parity violation in beauty mesons.
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Journal articleAbubakar S, Acero MA, Acharya B, et al., 2026,
Precision Measurement of Neutrino Oscillation Parameters with 10 Years of Data from the NOvA Experiment.
, Phys Rev Lett, Vol: 136This Letter reports measurements of muon-neutrino disappearance and electron-neutrino appearance and the corresponding antineutrino processes between the two NOvA detectors in the NuMI neutrino beam. These measurements use a dataset with double the neutrino mode beam exposure that was previously analyzed, along with improved simulation and analysis techniques. A joint fit to these samples in the three-flavor paradigm results in the most precise single-experiment constraint on the atmospheric neutrino mass splitting, Δm_{32}^{2}=2.431_{-0.034}^{+0.036}(-2.479_{-0.036}^{+0.036})×10^{-3} eV^{2} if the mass ordering is normal (inverted). In both orderings, a region close to maximal mixing with sin^{2}θ_{23}=0.55_{-0.06}^{+0.02} is preferred. The NOvA data show a mild preference for the normal mass ordering with a Bayes factor of 2.4 (corresponding to 70% of the posterior probability), indicating that the normal ordering is 2.4 times more probable than the inverted ordering. When incorporating a 2D Δm_{32}^{2}-sin^{2}2θ_{13} constraint based on Daya Bay data, this preference strengthens to a Bayes factor of 6.6 (87%).
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Simultaneous Probe of the Charm and Bottom Quark Yukawa Couplings Using tt[over ¯]H Events.
, Phys Rev Lett, Vol: 136A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, H→cc[over ¯], produced in association with a top quark-antiquark pair (tt[over ¯]H) is presented. The search is performed with data from proton-proton collisions at sqrt[s]=13 TeV, corresponding to an integrated luminosity of 138 fb^{-1}. Advanced machine learning techniques are employed for jet flavor identification and event classification. The Higgs boson decay to a bottom quark-antiquark pair is measured simultaneously and the observed tt[over ¯]H(H→bb[over ¯]) event rate relative to the standard model expectation is 0.91_{-0.22}^{+0.26}. The observed (expected) upper limit on the product of production cross section and branching fraction σ(tt[over ¯]H)B(H→cc[over ¯]) is 0.11 (0.13) pb at 95% confidence level, corresponding to 7.8 (8.7) times the standard model prediction. When combined with the previous search for H→cc[over ¯] via associated production with a W or Z boson, the observed (expected) 95% confidence interval on the Higgs-charm Yukawa coupling modifier, κ_{c}, is |κ_{c}|<3.5 (2.7), the most stringent constraint to date.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026,
A model-independent measurement of the CKM angle γ in the decays B±→ [K+K−π+π−]Dh± and B±→ [π+π−π+π−]Dh± (h = K, π)
, Journal of High Energy Physics, Vol: 2026A model-independent determination of the CKM angle γ is presented, using the B<sup>±</sup> → [K<sup>+</sup>K<sup>−</sup>π<sup>+</sup>π<sup>−</sup>]<inf>D</inf>h<sup>±</sup> and B<sup>±</sup> → [π<sup>+</sup>π<sup>−</sup>π<sup>+</sup>π<sup>−</sup>]<inf>D</inf>h<sup>±</sup> decays, with h = K, π. This measurement is the first phase-space binned study of these decay modes, and uses a sample of proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb<sup>−1</sup>. The phase-space bins are optimised for sensitivity to γ, and in each bin external inputs from the BESIII experiment are used to constrain the charm strong-phase parameters. The result of this binned analysis is γ=53.9−8.9+9.5°, where the uncertainty includes both statistical and systematic contributions. Furthermore, when combining with existing phase-space integrated measurements of the same decay modes, a value of γ=52.6−6.4+8.5° is obtained, which is one of the most precise determinations of γ to date.
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Journal articleAlt C, Blanchet A, Bordoni S, et al., 2026,
Modeling scintillation photon transport and reconstruction algorithms for the time-of-flight detector in the T2K neutrino experiment
, Journal of Instrumentation, Vol: 21, Pages: P01041-P01041<jats:title>Abstract</jats:title> <jats:p> The T2K ND280 upgrade aims to reduce the systematic uncertainty of the CP-violating phase, <jats:italic>δ</jats:italic> <jats:sub>CP</jats:sub> , to reject non-CP violation hypothesis at 3 <jats:italic>σ</jats:italic> confidence level. A crucial component of the ND280 upgrade, alongside the Super Fine Grained Detector (SuperFGD) and two High-Angle Time Projection Chambers (TPCs), is the Time-of-Flight (ToF) detector, which significantly enhances background rejection and particle identification capabilities. The ToF detector features six modules in a cube configuration, each with 20 plastic scintillator bars measuring 220×12×1 cm <jats:sup>3</jats:sup> and is equipped with Silicon Photomultiplier (MPPC) arrays at both ends to capture scintillation light. This letter outlines the modelling of the detector response and the signal reconstruction process. </jats:p>
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2026,
Measurements of the inclusive W and Z boson production cross sections and their ratios in proton-proton collisions at TeV
, Journal of High Energy Physics, Vol: 2026Measurements are presented of the W and Z boson production cross sections in proton-proton collisions at a center-of-mass energy of 13.6 TeV. Data collected in 2022 and corresponding to an integrated luminosity of 5.01 fb<sup>−1</sup> with one or two identified muons in the final state are analyzed. The results for the products of total inclusive cross sections and branching fractions for muonic decays of W and Z bosons are (acceptance) nb for W<sup>+</sup> boson production, (acceptance) nb for W<sup>−</sup> boson production, and (acceptance) nb for the Z boson production in the dimuon mass range of 60–120 GeV, all with negligible statistical uncertainties. Furthermore, the corresponding fiducial cross sections, as well as cross section ratios for both fiducial and total phase space, are provided. The ratios include charge-separated results for W boson production (W<sup>+</sup> and W<sup>−</sup>) and the sum of the two contributions (W<sup>±</sup>), each relative to the measured Z boson production cross section. Additionally, the ratio of the measured cross sections for W<sup>+</sup> and W<sup>−</sup> boson production is reported. All measurements are in agreement with theoretical predictions, calculated at next-to-next-to-leading order accuracy in quantum chromodynamics.
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Journal articleAbe K, Abe S, Akutsu R, et al., 2025,
Results from the T2K Experiment on Neutrino Mixing Including a New Far Detector μ-like Sample.
, Phys Rev Lett, Vol: 135We have made improved measurements of three-flavor neutrino mixing with 19.7(16.3)×10^{20} protons on target in (anti-)neutrino-enhanced beam modes. A new sample of muon-neutrino events with tagged pions has been added at the far detector, as well as new proton and photon-tagged samples at the near detector. Significant improvements have been made to the flux and neutrino interaction modeling. T2K data continue to prefer the normal mass ordering and upper octant of sin^{2}θ_{23} with a near-maximal value of the charge-parity violating phase with best-fit values in the normal ordering of δ_{CP}=-2.18_{-0.47}^{+1.22}, sin^{2}θ_{23}=0.559_{-0.078}^{+0.018} and Δm_{32}^{2}=(+2.506_{-0.052}^{+0.039})×10^{-3} eV^{2}.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2025,
First Observation of the Charmless Baryonic Decay B^{+}→Λ[over ¯]pp[over ¯]p.
, Phys Rev Lett, Vol: 135A search for the charmless baryonic decay B^{+}→Λ[over ¯]pp[over ¯]p is performed using proton-proton collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 5.4 fb^{-1}. The branching fraction for this decay is measured for the first time relative to that of the topologically similar decay B^{+}→J/ψK^{+}, with J/ψ→Λ[over ¯]pK^{-}. The branching fraction is measured to be B(B^{+}→Λ[over ¯]pp[over ¯]p)=(2.15±0.35±0.12±0.28)×10^{-7}, where the first uncertainty is statistical, the second is systematic, and the third arises from the uncertainty in the normalization channel branching fraction. The CP asymmetry is measured to be A_{CP}=(5.4±15.6±2.4)%, where the uncertainties are statistical and systematic. The background-subtracted invariant-mass distributions of Λ[over ¯]p and p[over ¯]p pairs exhibit pronounced enhancements at both kinematic thresholds, in contrast to a uniform phase-space distribution.
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2025,
Observation of Coherent ϕ(1020) Meson Photoproduction in Ultraperipheral PbPb Collisions at sqrt[s_{NN}]=5.36 TeV.
, Phys Rev Lett, Vol: 135The first observation of coherent ϕ(1020) meson photoproduction off heavy nuclei is presented using ultraperipheral lead-lead collisions at a center-of-mass energy per nucleon pair of 5.36 TeV. The data were collected by the CMS experiment and correspond to an integrated luminosity of 1.62 μb^{-1}. The ϕ(1020) meson signals are reconstructed via the K^{+}K^{-} decay channel. The production cross section is presented as a function of the ϕ(1020) meson rapidity in the range 0.3<|y|<1.0, probing gluons that carry a fraction of the nucleon momentum (x) around 10^{-4}. The observed cross section exhibits little dependence on rapidity and is significantly suppressed, by a factor of ∼5, compared to a baseline model that treats a nucleus as a collection of free nucleons. Theoretical models that incorporate the nuclear shadowing effect generally provide a better description of the ϕ(1020) data than those incorporating gluon saturation. This study establishes a powerful new tool for exploring nuclear effects and nuclear gluonic structure in the small-x regime at a unique energy scale bridging the perturbative and nonperturbative quantum chromodynamics domains.
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Conference paperAlden N, Ali S, Allison P, et al., 2025,
First Array-Wide Search for Diffuse UHE Neutrinos with the Askaryan Radio Array
The Askaryan Radio Array (ARA) is an ultrahigh energy (UHE) neutrino detector at the South Pole, designed to search for radio pulses emitted by neutrino-initiated particle showers in ice. ARA consists of an array of five autonomous stations with 2 km spacing. Each station consists of 16 radio antennas embedded ∼200 m deep in the ice that are sensitive to either vertically- or horizontally-polarized signals. Radio arrays like ARA represent a cost-efficient means of achieving the enormous detection O(10 km<sup>3</sup>) volumes necessary for UHE neutrino detection. This contribution presents the current status of the first-ever array-wide search for UHE neutrinos, leveraging ARA’s unprecedented ∼28 station-years of livetime. This search will have the best sensitivity of any neutrino detector above 3 EeV, sufficient to probe the 220 PeV flux inferred from KM3NeT’s observation of KM3-230213A. Importantly, this study demonstrates the feasibility of array-wide neutrino searches, which are necessary for next-generation detectors, like RNO-G (35 stations planned) and IceCube-Gen2 Radio (361 stations proposed), to achieve their design sensitivity. We discuss the progress towards a fully analyzed sample and improvements to ARA’s detector characterization and analysis sensitivity.
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Conference paperAbarr Q, Allison P, Alvarez-Muñiz J, et al., 2025,
Neutrino Flavor Identification at the Highest Energies with PUEO
PUEO (the Payload for Ultra-high Energy Observations) is an Antarctic, balloon-borne experiment that aims to detect neutrinos above EeV energies primarily by searching for Askaryan radiation sourced from particle cascades induced by interactions within the ice. At the highest energies, neutrinos predominantly undergo charged-current interactions, producing high energy charged leptons which can induce secondary cascades during their propagation. PUEO is particularly sensitive to these secondary cascades for 2 reasons: i) high altitude observations provide long distances (O(100km)) to observed radiation, ensuring similar angles to the payload. This geometry allows for multi-pulse topology to occur readily within single detection windows ii) the pulse shape produced by Askaryan emission is dependent on interaction type (hadronic/electromagnetic/hybrid) and differentiation can point to charged-lepton flavor identification. In this talk, we discuss PUEO’s ability to measure and characterize secondary cascades in ice, moving towards a robust method for neutrino flavor identification at the highest energies. We also discuss how PUEO’s characterization of these secondary cascades helps to constrain neutrino energy and direction, both of which are crucial for multi-messenger based observations.
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Conference paperSeikh MFH, Besson D, Giri P, et al., 2025,
Techniques for Continuous Wave Identification and Filtering in the Askaryan Radio Array
The Askaryan Radio Array (ARA), located near the geographical South Pole, is among the first experiments at the South Pole designed to detect ultra-high energy neutrinos through the Askaryan effect. When such neutrinos interact within dense media such as ice, they initiate particle cascades that, as they evolve, generate coherent radio pulses. Operating in the 150–850 MHz frequency band, ARA is deployed 80–200 meters deep in Antarctic ice, where the radio frequency background is exceptionally low. Despite the low background, experiments such as ARA must still account for continuous wave (CW) signals, which can originate from anthropogenic sources, instrumental noise, and other environmental factors. These CW signals can potentially obscure the faint neutrino-induced radio pulses, complicating data analysis and event identification. Over the years, ARA has developed and refined a number of techniques for CW filtering and identification, including spectral analysis, notch filtering, and phase-variance methods. These approaches exploit the unique characteristics of CW signals, such as their narrowband nature and temporal persistence, to effectively separate CW contamination from genuine impulsive events. We review the main CW identification and filtering techniques developed within the ARA collaboration and present recent improvements in their adaptive, multi-stage filtering pipelines. These advances have led to faster processing, easier operation, and more accurate CW identification and suppression, improving the consistency and quality of data analysis. The efficacy of these methods is demonstrated through CW identification and filtering for all ARA stations, showcasing their critical role in reducing event misclassification and improving the experiment’s overall performance. By refining these techniques, this work not only improves the sensitivity and data analysis performance of ARA, but also underscores the importance of robust CW identification
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Conference paperWindischhofer P, Alden N, Alden N, et al., 2025,
Observation of Broadband In-ice Radiation from Impacting High-Energy Cosmic Rays
We present the first experimental evidence for in-ice radiofrequency emission from high-energy particle cascades developing in the Antarctic ice sheet. In 208 days of data recorded with the phased-array trigger of the Askaryan Radio Array, we detect 13 events with impulsive radiofrequency pulses originating from below the ice surface. Considering only the arrival angles and timing properties, this rate is inconsistent with an a-posteriori background expectation for thermal noise events and on-surface events at the level of 3.5 σ, which rises to 5.1 σ when additionally considering impulsivity. The observed event geometry, event rate, signal shape, spectral content, and electric field polarization are consistent with Askaryan radiation from cosmic ray air shower cores impacting the ice sheet. For the brightest events, the angular radiation pattern independently favors an extended cascade-like emitter over a pointlike source.
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Conference paperAlden N, Ali S, Allison P, et al., 2025,
Advancing ARA: the Next-Generation (ARA-Next) DAQ System
The Askaryan Radio Array (ARA) has been operating at the South Pole for over a decade, searching for ultra-high-energy astrophysical and cosmogenic neutrinos using the Askaryan effect. ARA has consistently served as a testbed for innovative trigger designs and advancing electronic upgrades, with ongoing data acquisition (DAQ) improvements over the past 2–3 years and a long-term plan to transition to Radio Frequency System-on-Chip (RFSoC) technology. This upgrade enables real-time data processing and sophisticated triggers, enhancing efficiency by identifying double pulses from in-ice neutrino interactions, using templates for cosmic rays, searching for real-time coincidences with the IceCube detector observations, and filtering anthropogenic noise through directional analysis. In 2024, two of the five ARA stations received DAQ upgrades, improving the existing electronics, with RFSoC-based DAQ foreseen in the coming years. In this proceedings contribution, recent ARA activities are presented, with emphasis on the planned ARA-Next trigger strategies involving RFSoC technology and the 2024–2025 season upgrades of the existing ATRI-based DAQ system to its revised version.
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Conference paperAli S, Besson DZ, Alden N, et al., 2025,
First Ultra High Energy Neutrino Search with a Hybrid Phased and Traditional Detector in the Askaryan Radio Array
The Askaryan Radio Array (ARA) is an in-ice ultrahigh energy (UHE, >10 PeV) neutrino experiment at the South Pole, designed to detect neutrino-induced radio emission in ice. It consists of five independent stations, each featuring a cubic lattice of in-ice antenna clusters spaced 30 m apart and buried 200 m below the surface. The fifth ARA station (A5) is unique due to its central phased array string, which employs an interferometric trigger to enhance sensitivity to weak signals otherwise buried in noise. This low-threshold trigger makes ARA the first in-ice radio neutrino experiment to demonstrate a significant improvement in detecting low signal-to-noise ratio (SNR) radio signals. We present progress toward the first UHE neutrino search utilizing A5’s hybrid detection capability, incorporating advancements in data selection and background rejection. This analysis is the first to fully apply dedicated event selection to both components of ARA’s hybrid detector, improving directional reconstruction and significantly enhancing background rejection compared to previous analyses. This approach paves the way for next-generation in-ice UHE neutrino experiments.
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Conference paperAli S, Besson DZ, Alden N, et al., 2025,
High-Fidelity Simulations of the Full Askaryan Radio Array and its Sensitivity to Ultra-High Energy Neutrinos
The Askaryan Radio Array (ARA) is a five-station, in-ice radio detector located at the South Pole searching for particle cascades from cosmogenic and astrophysical neutrinos with ≥ 10<sup>17</sup> eV of energy. Cascades in this energy regime emit radio-wavelength Askaryan radiation that can be observed by one or more ARA stations. With the recent KM3Net observation of an approximately 220 PeV neutrino, there is renewed, urgent interest in further unlocking the ultra-high energy neutrino sky. We present updated calculations of ARA’s array-wide effective volume, sensitivity, and expected event rates for ultra-high energy neutrino-induced cascades. Notably, results now account for the contributions of secondary particles from neutrino interactions (such as muon tracks) and multi-station detections within a detailed detector simulation framework. Previous work has shown these secondary interactions and multi-station coincidences compose 25% and 8% of the detector’s effective area, respectively. We intend to extend these results towards a novel analysis that estimates the degree to which secondary cascades and multi-station observations are detectable in a real neutrino search. This will inform future UHE neutrino searches as it will characterize the feasibility of detecting such events.
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Conference paperMcBride K, Abarr Q, Allison P, et al., 2025,
Design of the Payload for Ultrahigh Energy Observations
Ultrahigh-energy cosmic rays (UHECR) should produce ultrahigh-energy neutrinos (UHEN) as byproducts of their propagation. Many candidate UHECR source models also predict an emission of UHEN local to their acceleration sites. The Payload for Ultrahigh Energy Observations (PUEO) is a balloon-borne observatory that will scan the Antarctic ice for these UHEN through their Askaryan emission and is the successor to the ANtarctic Impulsive Transient Antenna (ANITA). The payload design is optimized to detect these Askaryan signals with wide bandwidth measurements of dual-polarized antennas. The challenge in reaching high neutrino sensitivity includes outfitting many low-noise channels with linear polarization measurements and efficient filtering of backgrounds with size, power, and weight constraints to fit on a balloon-borne instrument. This poster will present the antennas, filtering, and data acquisition system in the context of meeting the science requirements of the PUEO mission.
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Conference paperAbarr Q, Allison P, Alvarez-Muñiz J, et al., 2025,
Searching for Ultrahigh Energy Neutrinos with PUEO
PUEO, the Payload for Ultrahigh Energy Observations, is a long duration balloon-borne experiment with the primary science goal of detecting the impulsive Askaryan emission from ultrahigh energy (UHE, >1 EeV) neutrinos interacting in the ice sheet of Antarctica. The ultrahigh energy neutrino flux is yet to be detected, and so a successful measurement by PUEO will give us information about the where and how these neutrinos are produced; this may be through a process called the GZK effect when ultrahigh energy cosmic rays interact with the cosmic microwave background, or it may be directly within the environment of cosmic ray accelerators. In order to detect radio Askaryan emission, PUEO consists of a broadband interferometric radio detector of 96 antennas which point down at the ice. Additionally, it has a drop-down low-frequency subsystem which will deploy after launch. This improves PUEO’s ability to detect tau neutrinos and charged cosmic rays, which can both produce geomagnetic air shower emission. This contribution will outline PUEO’s science case, present its expected sensitivity, and share status updates from our preparation to launch PUEO from McMurdo Station, Antarctica in December 2025.
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Conference paperAli S, Besson DZ, Alden N, et al., 2025,
Study of an Isolated Double-pulse Cosmic Ray Candidate Recorded with the Askaryan Radio Array
The radio-frequency emissions produced by particle showers on Earth, resulting from cosmic rays (CRs) and ultra-high energy neutrinos (UHE-ν) originating from astrophysical sources share significant similarities, enabling radio detectors initially designed for UHE-ν searches to also study CRs. The Askaryan Radio Array (ARA), an experiment currently operating within the ice at the South Pole, is primarily designed to detect UHE-νs. To date, ARA has deployed five stations, with each station equipped with antennas installed at depths up to 200 meters in the ice. Data recorded by ARA Station-2 (A2) suggest a potential CR origin for a subset of events identified in a UHEν search. This subset includes a double-pulse event potentially from a downward propagating CR-induced air shower, with in-air geomagnetic emission followed by in-ice Askaryan emission producing the two pulses. A detailed investigation of this CR candidate event using comprehensive simulations has been conducted with the goal of identifying the parameters of a CR-induced air shower that best match the experimentally observed quantities. We simulate predicted CR signals in ARA by combining an impacting CR shower simulation framework (FAERIE) with a realistic detector simulation (AraSim). We determine the event topology based on the vertex reconstruction of both the putative geomagnetic and Askaryan signals. After inferring the event geometry, we show that the simulation matches the observed time structure of the event (channel-by-channel relative signal arrival times) for the recorded event.
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Conference paperAbarr Q, Allison P, Alvarez-Muñiz J, et al., 2025,
The Payload for Ultrahigh Energy Observations (PUEO): Detector Design and Implementation
The Payload for Ultrahigh Energy Observations (PUEO) is slated to fly in December of this year out of McMurdo Station in Antarctica in search of the highest energy neutrinos produced in our Universe. PUEO is designed to detect Askaryan emission, a broadband radio signal that occurs when a neutrino interacts in a dense dielectric medium like Antarctic ice. To achieve better sensitivity than ANITA, its predecessor, PUEO has redesigned its antennas and trigger to benefit from the advanced beamforming capabilities of the RF-System on Chip (RFSoC). PUEO will fly with two instruments: the main instrument, targeting the Askaryan emission from ultra-high energy neutrino flux, and the low frequency instrument, targeting radio emission from air showers induced by cosmic rays and tau neutrinos. Each detector is being carefully designed and modeled to maximize the potential sensitivity to these cosmic events. In this contribution, I will discuss the status of the PUEO instrument, which is currently undergoing integration and testing in advance of its upcoming 30-day mission. In particular, I will present our current expectations for hardware performance, our implementation of a drop-down Low Frequency Instrument, and our final areas of development prior to the flight. Finally, I will report on our simulation package, PUEOSim, and our progress towards modeling our instrument to prepare for both PUEO’s launch and for future analyses.
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2025,
General search for supersymmetric particles in scenarios with compressed mass spectra using proton-proton collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mtext> </mml:mtext> <mml:mtext> </mml:mtext> <mml:mi>TeV</mml:mi> </mml:math>
, Physical Review D, Vol: 112, ISSN: 2470-0010<jats:p> A general search is presented for supersymmetric particles (sparticles) in scenarios featuring compressed mass spectra using proton-proton collisions at a center-of-mass energy of 13 TeV, recorded with the CMS detector at the LHC. The analyzed data sample corresponds to an integrated luminosity of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mn>138</a:mn> <a:mtext> </a:mtext> <a:mtext> </a:mtext> <a:msup> <a:mi>fb</a:mi> <a:mrow> <a:mo>−</a:mo> <a:mn>1</a:mn> </a:mrow> </a:msup> </a:math> . A wide range of potential sparticle signatures are targeted, including pair production of electroweakinos, sleptons, and top squarks. The search focuses on events with a high transverse momentum system from initial-state-radiation jets recoiling against a potential sparticle system with significant missing transverse momentum. Events are categorized based on their lepton multiplicity, jet multiplicity, number of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>b</c:mi> </c:math> -tagged jets, and kinematic variables sensitive to the sparticle masses and mass splittings. The sensitivity extends to higher parent sparticle masses than previously probed at the LHC for production of pairs of electroweakinos, sleptons, and top squarks with mass spectra featuring small mass splittings (compressed mass spectra). The observed results demonstrate agreemen
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2025,
Search for charged lepton flavor violating <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>Z</mml:mi> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msup> <mml:mi>Z</mml:mi> <mml:mo>′</mml:mo> </mml:msup> </mml:math> boson decays in proton-proton collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mtext> </mml:mtext> <mml:mtext> </mml:mtext> <mml:mi>TeV</mml:mi> </mml:math>
, Physical Review D, Vol: 112, ISSN: 2470-0010<jats:p> A search for flavor violating decays of the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>Z</a:mi> </a:math> boson to charged leptons is performed using data from proton-proton collisions at <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msqrt> <c:mi>s</c:mi> </c:msqrt> <c:mo>=</c:mo> <c:mn>13</c:mn> <c:mtext> </c:mtext> <c:mtext> </c:mtext> <c:mi>TeV</c:mi> </c:math> collected with the CMS detector at the LHC, corresponding to an integrated luminosity of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mn>138</e:mn> <e:mtext> </e:mtext> <e:mtext> </e:mtext> <e:msup> <e:mi>fb</e:mi> <e:mrow> <e:mo>−</e:mo> <e:mn>1</e:mn> </e:mrow> </e:msup> </e:math> . Each of the decays <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mi>Z</g:mi> <g:mo stretchy="false">→</g:mo> <g:mi>e</g:mi>
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2025,
Measurement of event shapes in minimum-bias events from proton-proton collisions at √s = 13 TeV
, Physical Review D, Vol: 112, ISSN: 2470-0010A measurement of event-shape variables is presented, using a data sample produced in a special run with approximately one inelastic proton-proton collision per bunch crossing. The data were collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 64 μb<sup>−1</sup>. A number of observables related to the overall distribution of charged particles in the collisions are corrected for detector effects and compared with simulations. Inclusive event-shape distributions, as well as differential distributions of event shapes as functions of charged-particle multiplicity, are studied. None of the models investigated are able to satisfactorily describe the data. Moreover, there are significant features common amongst all generator setups studied, particularly showing data being more isotropic than any of the simulations. Multidimensional unfolded distributions are provided, along with their correlations.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Search for New Physics in Jet Multiplicity Patterns of Multilepton Events at sqrt[s]=13 TeV.
, Phys Rev Lett, Vol: 135A first search for beyond the standard model physics in jet multiplicity patterns of multilepton events is presented, using a data sample corresponding to an integrated luminosity of 138 fb^{-1} of 13 TeV proton-proton collisions recorded by the CMS detector at the LHC. The search uses observed jet multiplicity distributions in one-, two-, and four-lepton events to explore possible enhancements in jet production rate in three-lepton events with and without bottom quarks. The data are found to be consistent with the standard model expectation. The results are interpreted in terms of supersymmetric production of electroweak chargino-neutralino superpartners with cascade decays terminating in prompt hadronic R-parity violating interactions.
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