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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Highly boosted dielectron identification 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: 114, ISSN: 2470-0010<jats:p> A new technique is developed to identify dielectrons ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:msup> <a:mi>e</a:mi> <a:mo>+</a:mo> </a:msup> <a:msup> <a:mi>e</a:mi> <a:mo>−</a:mo> </a:msup> </a:mrow> </a:math> ) with Lorentz boost <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msub> <c:mi>γ</c:mi> <c:mi mathvariant="normal">L</c:mi> </c:msub> <c:mo>></c:mo> <c:mn>20</c:mn> </c:math> that produce one single merged cluster in the electromagnetic calorimeter of the CMS detector. The identification uses two multivariate models: one for the case where both electron tracks are reconstructed, and another where only one of the tracks is reconstructed. The efficiency is determined using proton-proton collision data collected at a center-of-mass energy of 13 TeV. Boosted <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"> <f:mi>J</f:mi> <f:mo>/</f:mo> <f:mi>ψ</f:mi> </f:math> mesons decaying into <h:math xmlns:h="http://www.w3.org/199
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Search for Associated Production of a Higgs Boson and Two Vector Bosons via Vector-Boson Scattering at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msqrt> <mml:mrow> <mml:mi>s</mml:mi> </mml:mrow> </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:mrow> </mml:math>
, Physical Review Letters, Vol: 137, ISSN: 0031-9007<jats:p> A search for Higgs boson ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>H</a:mi> </a:math> ) production in association with two vector bosons ( <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>V</c:mi> <c:mo>=</c:mo> <c:mi>W</c:mi> </c:math> , <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mi>Z</e:mi> </e:math> ) via vector-boson scattering (VBS) is presented using proton-proton collision data collected at <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:msqrt> <g:mi>s</g:mi> </g:msqrt> <g:mo>=</g:mo> <g:mn>13</g:mn> <g:mtext> </g:mtext> <g:mtext> </g:mtext> <g:mi>TeV</g:mi> </g:math> by the CMS experiment, corresponding to an integrated luminosity of <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"> <i:mn>138</i:mn> <i:mtext> </i:mtext> <i:mtext> </i:mtext> <i:msup> <i:mi>fb</i:mi> <i:m
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Journal articleMorgan K, Azuma T, Baptista G, et al., 2026,
Transition-Edge Sensor Spectrometer for Precision Spectroscopy of Antiprotonic Atoms
, IEEE Transactions on Applied Superconductivity, Vol: 36, ISSN: 1051-8223antiProtonic Atom X-ray (PAX) spectroscopy is an experiment that aims to test strong-field quantum electrodynamics (QED) effects by performing high-precision X-ray spectroscopy of antiprotonic atoms. PAX will use a low-energy antiproton beam provided by the Extra Low ENergy Antiproton (ELENA) ring at the European Organization for Nuclear Research (CERN) to create antiprotonic atoms. A superconducting transition-edge sensor (TES) spectrometer will be used to measure the energy of transitions between circular Rydberg states in these atoms. The energy range of interest for the experiment spans 50 keV to 250 keV, and the desired precision for measuring the centroids of the emission lines is 10^{-5}. The spectrometer for PAX is intended to have four 96-pixel TES arrays and will be read out with a microwave superconducting quantum interference device (SQUID) multiplexer. As a step toward building the full instrument, we built a scaled-down version of the spectrometer that was installed at the TEst Line for Machine And Antimatter eXperiments (TELMAX) facility at ELENA in April 2025. The purpose of this deployment was to make an observation of X-ray emission by antiprotonic atoms and to better understand the effect of the pionic charged particle background due to antiproton annihilation on the performance of the TES array. This pilot spectrometer had an array of 60 TES pixels in a compact adiabatic demagnetization refrigerator cryostat. The sensors were read out with a microwave SQUID multiplexer. Each pixel consisted of a molybdenum/gold bilayer TES with a coplanar gold “landing pad” for a bulk tin absorber that was attached by an epoxy joint. We discuss the design of the TES pixels, the microwave SQUID readout, and the cryogenic platform. Finally, we present calibration data obtained at TELMAX using radioactive sources to assess the performance of the spectrometer in the antiproton beam-off condition.
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Journal articleWalker T, Marchant AL, Bentine E, et al., 2026,
A high-flux source of cold strontium with a loading rate of 4×1010 atoms/s for open release
, Avs Quantum Science, Vol: 8We present a high-flux source of cold strontium atoms based on a two-dimensional magneto-optical trap (2D MOT) and a Zeeman slower. We use the source to load a 3D MOT in a separate science chamber, observing a loading rate of 4 × 10<sup>10</sup> atoms / s—to our knowledge, the highest reported loading flux for strontium. To characterize the vacuum pressure in the science chamber, we load the atoms into a magnetic trap and measure a lifetime of between 8 and 24 s, depending on the oven temperature. Finally, we characterize the atom flux and velocity distributions from the oven and from the 2D MOT source, finding reasonable agreement with models in the free molecular flow regime. Our results show that it is possible to readily produce a cold strontium flux at comparable levels to those of alkali species, at oven temperatures compatible with long-term operation, and at vacuum pressures suitable for state-of-the-art quantum experiments. We make our design available at no cost to benefit researchers in the quantum community.
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Journal articleBelyaev A, Gevorgyan A, Hayrapetyan A, et al., 2026,
System-size dependence of charged-particle suppression in ultrarelativistic nucleus-nucleus collisions
, Physics Letters Section B Nuclear Elementary Particle and High Energy Physics, Vol: 880, ISSN: 0370-2693High-energy partons lose energy while propagating through the hot, strongly interacting medium produced in ultrarelativistic nucleus-nucleus collisions, leading to a suppression of particle production at high transverse momentum (p <inf>T</inf>). The dependence of this energy loss on the size of the colliding nuclear system has yet to be firmly established experimentally. This Letter presents a systematic study of charged-particle suppression across four different nucleus-nucleus collision systems using nuclear modification factors (R <inf>AA</inf>) measured by the CMS Collaboration at the CERN LHC. Previous CMS measurements of R <inf>AA</inf> in oxygen-oxygen, xenon-xenon, and lead-lead collisions are recast with identical p <inf>T</inf> intervals and are complemented by the first measurement of the charged-particle R <inf>AA</inf> in neon-neon collisions at [b]s<inf>NN</inf>=5.36TeV. The neon-neon data correspond to an integrated luminosity of 0.76nb<sup>−1</sup>. The R <inf>AA</inf> in all collision systems examined show similar qualitative trends as a function of p <inf>T</inf>, but have a magnitude which is ordered with the nucleon number A . The R <inf>AA</inf> feature a downward slope at low p <inf>T</inf>, a local minimum at around 5–7GeV, and an upward slope with increasing p <inf>T</inf>. The R <inf>AA</inf> are also compared in terms of A <sup>1/3</sup>, which is proportional to the nuclear radius. Models including only initial-state nuclear effects fail to reproduce the observed trends, whereas energy loss models reproduce the trends in the region p<inf>T</inf>'9.6GeV.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Search for a new heavy resonance decaying to a top quark and a neutral scalar boson in proton-proton collisions at s=13TeV
, Physics Letters B, Vol: 880, Pages: 140812-140812, ISSN: 0370-2693 -
Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Full event interpretation with machine-learning-based particle-flow reconstruction in the CMS detector
, The European Physical Journal C, Vol: 86<jats:title>Abstract</jats:title> <jats:p> The particle-flow (PF) algorithm constructs a global description of each particle collision by producing a comprehensive list of final-state particles, and is central to event reconstruction in the CMS experiment at the CERN LHC. The existing PF implementation relies on physics-motivated heuristics and assumptions that can be replaced by machine-learning (ML) models trained directly on simulated data and naturally suited to modern graphics processing units (GPUs). A state-of-the-art ML-based PF (MLPF) reconstruction algorithm, implemented within the CMS software framework, is presented. The MLPF algorithm performs a learnable full-event reconstruction on GPUs, generalizes across detector conditions and collision energies, and replaces multiple modular reconstruction steps with a single unified model. Physics performance comparable to standard PF reconstruction is achieved in both simulation and data, with improved jet energy resolution and inference time. In simulated top quark-antiquark events under LHC Run-3 (2023–2024) conditions, the jet energy resolution improves by 10–20% for jets with transverse momentum between 30–100 GeV. Inference time is evaluated using simulated multijet events, with a median of <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$20\,\hbox {ms}$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>20</mml:mn> <mml:mspace/> <mml:mtext>ms</mml:mtext> </mml:mrow> </mml:math> </jats:alternatives> </jats:inl
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026,
Polarization Measurement of Λ_{c}^{+} and Λ[over ¯]_{c}^{-} Baryons in p-Ne Collisions at sqrt[s_{NN}]=68.6 GeV.
, Phys Rev Lett, Vol: 137The first measurement of the polarization of charm baryons by the LHCb experiment recorded in fixed-target mode is presented. The polarization of Λ_{c} baryons is studied in collisions of protons, at an energy of 2.51 TeV, incident on a gaseous target of neon, at a nucleon-nucleon center-of-mass energy of 68.6 GeV. The world's first measurement of separate-charge polarizations for Λ_{c}^{+} and Λ[over ¯]_{c}^{-} baryons is performed, determining P_{Λ_{c}^{+}}=(24±9±2)%, P_{Λ[over ¯]_{c}^{-}}=(-8±12±3)%, where the first uncertainty is statistical and the second systematic. The polarization is also measured in intervals of baryon transverse momentum and the Feynman-x variable.
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Journal articleAprile E, Aalbers J, Abe K, et al., 2026,
Probing the Solar <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mmultiscripts> <mml:mrow> <mml:mi mathvariant="normal">B</mml:mi> </mml:mrow> <mml:mprescripts/> <mml:none/> <mml:mrow> <mml:mn>8</mml:mn> </mml:mrow> </mml:mmultiscripts> </mml:mrow> </mml:math> Neutrino Fog with XENONnT
, Physical Review Letters, Vol: 137, ISSN: 0031-9007<jats:p> We report a <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mn>3.3</a:mn> <a:mi>σ</a:mi> </a:mrow> </a:math> measurement of coherent elastic neutrino-nucleus scattering from solar <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mrow> <c:mmultiscripts> <c:mrow> <c:mi mathvariant="normal">B</c:mi> </c:mrow> <c:mprescripts/> <c:none/> <c:mrow> <c:mn>8</c:mn> </c:mrow> </c:mmultiscripts> </c:mrow> </c:math> neutrinos using a <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"> <f:mrow> <f:mn>6.77</f:mn> <f:mtext> </f:mtext> <f:mtext> </f:mtext> <f:mi mathvariant="normal">t</f:mi> <f:mo>×</f:mo> <f:mi>yr</f:mi> </f:mrow> </f:math> exposure from the XENONnT experiment, inferring a solar <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline">
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Evidence of ZZγ Production and Observation of 4ℓγ in Proton-Proton Collisions at sqrt[s]=13 TeV.
, Phys Rev Lett, Vol: 137Evidence of the production of two Z bosons and a photon in proton-proton collisions is reported for the first time in CMS. The analysis uses data collected by the CMS experiment between 2016 and 2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb^{-1}. Evidence for the process pp→ZZγ→4ℓγ (ℓ=e, μ), with an observed (expected) significance of 3.7 (3.1) standard deviations in a fiducial region defined by p_{T}^{γ}>20 GeV, |η^{γ}|<2.4, ΔR(ℓ,γ)>0.5, m_{Z} between 60 and 120 GeV, and the invariant mass of either of the two Z bosons combined with the photon (m_{Z_{γ}}) larger than 100 GeV, is reported. The measured (predicted) fiducial cross section is 60_{-22}^{+27} ab (47.56±0.04 ab). Additionally, the inclusive production of pp→4ℓγ is studied by removing the m_{Z_{γ}} requirement to include final state radiation where one Z boson decays to 2ℓγ, yielding an observed (expected) significance of 5.0 (4.2) standard deviations and a measured (predicted) fiducial cross section of 156_{-35}^{+39} ab (99.97±0.09 ab).
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Journal articleAkerib DS, Al Musalhi AK, Alder F, et al., 2026,
Searches for Light Dark Matter and Evidence of Coherent Elastic Neutrino-Nucleus Scattering of Solar Neutrinos with the LUX-ZEPLIN (LZ) Experiment.
, Phys Rev Lett, Vol: 137We present searches for light dark matter (DM) with masses 3-9 GeV/c^{2} in the presence of coherent elastic neutrino-nucleus scattering (CEνNS) from ^{8}B solar neutrinos with the LUX-ZEPLIN experiment. This analysis uses a 5.7 tonne-yr exposure with data collected between March 2023 and April 2025. In an energy range spanning 1-6 keV, we report no significant excess of events attributable to dark matter nuclear recoils, but we observe a significant signal from ^{8}B CEνNS interactions that is consistent with expectation. We set world-leading limits on spin-independent and spin-dependent-neutron DM-nucleon interactions for masses down to 5 GeV/c^{2}. In the no-dark-matter scenario, we observe a signal consistent with ^{8}B CEνNS events, corresponding to a 4.5σ statistical significance. This is the most significant evidence of ^{8}B CEνNS interactions and is enabled by robust background modeling and mitigation techniques. This demonstrates LZ's ability to detect rare signals at keV-scale energies.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Measurement of the t-channel single top quark cross section in proton-proton collisions at $$ \sqrt{s}=5.02 $$ TeV
, Journal of High Energy Physics, Vol: 2026<jats:title> A <jats:sc>bstract</jats:sc> </jats:title> <jats:p> The single top quark <jats:italic>t</jats:italic> -channel production cross section is measured in proton-proton collisions at the CERN LHC at <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \sqrt{s}=5.02 $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>5.02</mml:mn> </mml:math> </jats:alternatives> </jats:inline-formula> TeV, using data recorded with the CMS detector in 2017, corresponding to an integrated luminosity of 302 pb <jats:sup> <jats:italic>−</jats:italic> 1 </jats:sup> , and resulting in the first CMS measurement of the process at that energy. Events with one electron or muon and two or more jets, among which at least one is identified as originating from a b quark fragmentation, are analyzed. The combined cross section of single top quark (tq) and single top antiquark ( <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \overline{\mathrm{t}}\mathrm{q} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:m
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Journal articleAaij R, Abdelfatah M, Abdelmotteleb ASW, et al., 2026,
First Measurement of the Decay-Time-Integrated CP Asymmetry in B_{s}^{0}→D_{s}^{-}π^{+} Decays.
, Phys Rev Lett, Vol: 137A measurement of the flavor-untagged decay-time-integrated CP asymmetry in the flavor-specific decay B_{s}^{0}→D_{s}^{-}π^{+}, ⟨A_{untagged}^{s}⟩, is performed using proton-proton collision data collected by the LHCb experiment between 2016 and 2018 at a center-of-mass energy of 13 TeV, corresponding to a total integrated luminosity of 5.4 fb^{-1}. The CP asymmetry is measured in two D_{s}^{-} meson decay modes, D_{s}^{-}→K^{-}K^{+}π^{-} and D_{s}^{-}→π^{-}π^{+}π^{-}. The combined result, ⟨A_{untagged}^{s}⟩=(-1.4±5.9(stat)±1.1(syst))×10^{-3}, is consistent with the Standard Model expectation and provides a direct constraint on new physics in tree-level b-hadron decays.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Observation of Long-Range Collective Flow in O+O and Ne+Ne Collisions and Implications for Nuclear Structure Studies.
, Phys Rev Lett, Vol: 137The long-range collective flow of particles produced in oxygen-oxygen (O+O) and neon-neon (Ne+Ne) collisions is measured with the CMS detector at the CERN LHC. The data samples were collected at a center-of-mass energy per nucleon pair of 5.36 TeV, with integrated luminosities of 7 nb^{-1} and 0.8 nb^{-1} for O+O and Ne+Ne collisions, respectively. Two- and four-particle azimuthal correlations are measured over nearly five units of pseudorapidity. Significant elliptic (v_{2}) and triangular (v_{3}) flow harmonics are observed in both systems. The ratios of v_{n} coefficients between Ne+Ne and O+O collisions suggest sensitivity to the intrinsic nuclear structure of the respective Ne and O ions. Hydrodynamic models with ab initio nuclear structure inputs qualitatively reproduce the collision-overlap dependence of both the v_{n} values and the Ne+Ne to O+O ratios. These measurements provide new constraints when modeling the interplay of nuclear structure and collective dynamics in collisions of ^{16}O and ^{20}Ne ions, respectively.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026,
First Evidence of the Decay B^{+}→π^{+}e^{+}e^{-}.
, Phys Rev Lett, Vol: 137The first evidence for the decay B^{+}→π^{+}e^{+}e^{-} is reported using proton-proton collision data recorded by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb^{-1}. A signal excess with a significance of 3.2σ is observed and the branching fraction is measured to be B(B^{+}→π^{+}e^{+}e^{-})=(2.4_{-0.8}^{+0.9} _{-0.2}^{+0.4})×10^{-8}, where the first set of uncertainties is statistical and the second is systematic. The result is consistent with the Standard Model expectation.
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Journal articleAaij R, Abdelfatah M, Abdelmotteleb ASW, et al., 2026,
Study of Nuclear Effects on Charm Production in Light-Ion Collisions.
, Phys Rev Lett, Vol: 137The onset of nuclear effects in light-ion collisions is studied by measuring the ratio of D^{0} meson production between NeNe and OO collisions at a center-of-mass energy per nucleon pair of 5.36 TeV recorded by the LHCb detector. The D^{0} meson yields are measured differentially in transverse momentum (p_{T}) for 0.5<p_{T}<20 GeV in the rapidity (y) region 2.0<y<4.5, and are normalized to the total number of recorded inelastic nucleus-nucleus collisions in each data sample. The resulting production ratio shows evidence of variation as a function of p_{T}, which is inconsistent with predictions based on nuclear modification of nucleon structure alone. This measurement is consistent with the onset of quark-gluon plasma production with increasing nucleus size in high-energy nuclear collisions.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Observation of the Jet Diffusion Wake Using Dijets in Heavy-Ion Collisions.
, Phys Rev Lett, Vol: 137Energetic quarks and gluons traversing a hot and dense quark-gluon plasma deposit energy and momentum into the medium before hadronizing to collimated sprays of particles, known as jets. This energy-momentum deposition is expected to produce medium responses, collectively known as jet wakes, with "diffusion wake" denoting a depletion of particles in the direction opposite to the propagating jet. The diffusion wake is studied by comparing dijet-hadron correlations measured in lead-lead (PbPb) and proton-proton (pp) collisions. The analysis uses PbPb and pp data recorded at a nucleon-nucleon (NN) center-of-mass energy sqrt[s_{NN}]=5.02 TeV with the CMS detector at the CERN LHC. By exploring how the dijet-hadron correlation distributions differ for various pseudorapidity separations of the two jets in the dijet, the presence of a jet diffusion wake is firmly established. The diffusion wake signal has a significance greater than 5 standard deviations for charged particles in the transverse momentum range 1<p_{T}<2 GeV. The measurements are compared with model predictions with and without jet wake effects, providing new insights into quark-gluon plasma properties and the formation of jet-induced wakes.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
A search for microscopic black holes, string balls, and sphalerons in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV
, Journal of High Energy Physics, Vol: 2026<jats:title> A <jats:sc>bstract</jats:sc> </jats:title> <jats:p> A search for microscopic black holes, string balls, and electroweak sphalerons using proton-proton collisions at <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \sqrt{s}=13 $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> </mml:math> </jats:alternatives> </jats:inline-formula> TeV recorded with the CMS detector at the CERN LHC during the 2016–2018 data taking, and corresponding to an integrated luminosity of 138 fb <jats:sup> <jats:italic>−</jats:italic> 1 </jats:sup> , is presented. Two search strategies based on control samples in data are used. Model-independent limits on the cross section of physics phenomena with multiple energetic jets, leptons, and photons are set using a method that relies on the shape invariance of the scalar sum of the transverse momenta of all objects in the event. Model-dependent limits on black hole and sphaleron production are set using a newly introduced method that has been developed for the identification of collider events with distinct kinematic features by separating them into classes based on phase space proximity. In the context of models with large extra dimensions, semiclassical black holes and st
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Journal articleAbratenko P, Andrade Aldana D, Arellano L, et al., 2026,
Measurements of the electron neutrino-argon differential cross section without pions in the final state in MicroBooNE
, Physical Review D, Vol: 114, ISSN: 2470-0010<jats:p> We present a new measurement of the electron neutrino charged current cross section on argon without pions in the final state. This measurement uses the full MicroBooNE booster neutrino beam dataset of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mn>1.3</a:mn> <a:mo>×</a:mo> <a:msup> <a:mrow> <a:mn>10</a:mn> </a:mrow> <a:mrow> <a:mn>21</a:mn> </a:mrow> </a:msup> </a:mrow> </a:math> protons on target collected at Fermi National Accelerator Laboratory. Events are considered both with and without protons above the kinetic energy visibility threshold. Differential cross sections are extracted in proton and electron kinematics, including energy and angle relative to the neutrino beam direction. The relationship between the hadronic and leptonic systems is explored through the angle between the proton and electron directions. The resulting cross sections are compared to a variety of available generator predictions using different models of neutrino interactions. We find good agreement with most models in lepton kinematics and some discrepancies in the hadronic system modeling, particularly in proton angle. </jats:p>
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Search for a narrow resonance with a mass between 10 and 70 GeV decaying to a pair of photons 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: 114, ISSN: 2470-0010<jats:p> The existence of a new spin-zero particle with a mass below the electroweak scale is predicted by several theoretical models. Searches for resonant production of photon pairs at the LHC are able to probe these models. We present a search for a narrow resonance produced through gluon fusion that decays into a pair of photons with an invariant mass between 10 and 70 GeV, using a proton-proton collision dataset from the CMS experiment. This dataset, corresponding to an integrated luminosity of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mn>54.4</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> , was recorded in 2018 at a center-of-mass energy of 13 TeV using a newly introduced diphoton trigger that enabled exploration of the low-mass diphoton spectrum. No significant excess above the expected background is observed. Upper limits are set on the product of the gluon fusion production cross section and the branching fraction of the diphoton decay of a narrow resonance. An interpretation of these limits within an effective field theory framework for axionlike particles is also provided. </jats:p>
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Journal articleAaij R, Abdelfatah M, Abdelmotteleb ASW, et al., 2026,
Search for the Lepton-Flavor Violating Decays B^{+}→π^{+}μ^{±}e^{∓}.
, Phys Rev Lett, Vol: 137The first search for the lepton-flavor violating decays B^{+}→π^{+}μ^{±}e^{∓} in proton-proton collisions is presented, using data collected by the LHCb experiment between 2011 and 2018, corresponding to an integrated luminosity of 9 fb^{-1}. No significant signal is observed and an upper limit on the branching fraction is set at B(B^{+}→π^{+}μ^{±}e^{∓})<1.8×10^{-9} at the 90% confidence level, 2 orders of magnitude more restrictive than the most stringent upper limit to date. This is the first constraint on lepton-flavor violating b→d quark transitions at the LHC and also sets the most stringent upper limits to date on b→dμ^{±}e^{∓} transitions. Limits on left-handed and scalar scenarios beyond the standard model are also reported.
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Journal articleAaij R, Abdelfatah M, Abdelmotteleb ASW, et al., 2026,
CP Violation Analysis of Local and Nonlocal Amplitudes in the B[over ¯]^{0}→K[over ¯]^{*0}μ^{+}μ^{-} Decay.
, Phys Rev Lett, Vol: 137A search for CP violation in the B[over ¯]^{0}→K[over ¯]^{*0}μ^{+}μ^{-} decay is performed using proton-proton collision data collected by the LHCb experiment during Run 1 and Run 2, corresponding to an integrated luminosity of 8.4 fb^{-1}. The analysis exploits the full angular distribution of the decay, providing sensitivity to CP-violating effects in both vector and axial-vector contributions to this flavor-changing neutral-current process. The complex Wilson coefficients are determined within the weak effective theory through an unbinned maximum-likelihood fit to the angular observables, incorporating nonlocal hadronic amplitudes across the full dimuon mass spectrum. The precision of the CP-violation observables is improved by an order of magnitude relative to previous measurements, with the imaginary parts of the Wilson coefficients now determined more precisely than the real parts. No significant CP violation is observed, and the results are consistent with the standard model.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Search for a Higgs boson produced in association with a charm quark and decaying to a W boson pair in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV
, Journal of High Energy Physics, Vol: 2026<jats:title> A <jats:sc>bstract</jats:sc> </jats:title> <jats:p> This paper presents a search for a Higgs boson produced in association with a charm quark (cH) which allows to probe the Higgs-charm Yukawa coupling strength modifier <jats:italic>κ</jats:italic> <jats:sub>c</jats:sub> . Higgs boson decays to a pair of W bosons are considered, where one W boson decays to an electron and a neutrino, and the other W boson decays to a muon and a neutrino. The data, corresponding to an integrated luminosity of 138 fb <jats:sup> <jats:italic>−</jats:italic> 1 </jats:sup> , were collected between 2016 and 2018 with the CMS detector at the LHC at a center-of-mass energy of <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \sqrt{s}=13 $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> </mml:math> </jats:alternatives> </jats:inline-formula> TeV. Upper limits at the 95% confidence level (CL) are set on the ratio of the measured yield to the standard model expectation for cH production. The observed (expected) upper limit is 1065 (506), corresponding to an observed (expected) constraint of <jats:italic>|κ<
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2026,
Measurement of the Zγ production cross section and search for anomalous neutral triple gauge couplings in pp collisions at $$ \sqrt{s}=13 $$ TeV
, Journal of High Energy Physics, Vol: 2026<jats:title> A <jats:sc>bstract</jats:sc> </jats:title> <jats:p> A measurement of the fiducial cross section of the associated production of a Z boson and a high- <jats:italic>p</jats:italic> <jats:sub>T</jats:sub> photon, where the Z decays to two neutrinos, and a search for anomalous triple gauge couplings are reported. The results are based on data collected by the CMS experiment at the LHC in proton-proton collisions at <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \sqrt{s}=13 $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> </mml:math> </jats:alternatives> </jats:inline-formula> TeV during 2016–2018, corresponding to an integrated luminosity of 138 fb <jats:sup> <jats:italic>−</jats:italic> 1 </jats:sup> . The fiducial Zγ cross section, where a photon with a <jats:italic>p</jats:italic> <jats:sub>T</jats:sub> greater than 225 GeV is produced in association with a Z, and the Z decays to a <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \up
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Search for a new resonance decaying to a Higgs boson and a scalar boson in events with two <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>b</mml:mi> </mml:math> jets and two <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>Z</mml:mi> </mml:math> bosons in proton-proton collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mtext> </mml:mtext> <mml:mtext> </mml:mtext> <mml:mi>TeV</mml:mi> </mml:math>
, Physical Review D, Vol: 114, ISSN: 2470-0010<jats:p> A search is performed for a new resonance <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>X</a:mi> </a:math> decaying into a Higgs boson and a new scalar boson <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>Y</c:mi> </c:math> ( <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mi>H</e:mi> <e:mi>Y</e:mi> </e:math> ) including the case where <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mi>Y</g:mi> </g:math> is assumed to be a second Higgs boson ( <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"> <i:mi>H</i:mi> <i:mi>H</i:mi> </i:math> ), using proton-proton collision data collected at <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"> <k:msqrt> <k:mi>s</k:mi> </k:msqrt> <k:mo>=</k:mo> <k:mn>13</k:mn> <k:mtext> </k:mtext> <k:mtext> </k:mtext> <k:mi>TeV</k:mi> </k:math> , c
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Search for heavy scalar resonances decaying to Lorentz-boosted Higgs and Higgs-like bosons in the $$ \mathrm{b}\overline{\mathrm{b}}4\mathrm{q} $$ final state at $$ \sqrt{s}=13 $$ TeV
, Journal of High Energy Physics, Vol: 2026<jats:title> A <jats:sc>bstract</jats:sc> </jats:title> <jats:p> A search is performed for a heavy scalar resonance X decaying to a Higgs boson (H) and a Higgs-like scalar boson (Y) in the two bottom quark ( <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \mathrm{H}\to \mathrm{b}\overline{\mathrm{b}} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>H</mml:mi> <mml:mo>→</mml:mo> <mml:mi>b</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> </jats:alternatives> </jats:inline-formula> ) and four quark (Y → VV → 4q) final state, where V denotes a W or Z boson. Masses of the X between 900 and 4000 GeV and the Y between 60 and 2800 GeV are considered. The search is performed in data collected by the CMS experiment at the CERN LHC from proton-proton collisions at 13 TeV center-of-mass energy, with a data set corresponding to a total integrated luminosity of 138 fb <jats:sup> <jats:italic>−</jats:italic> 1 </jats:sup> . It targets the Lorentz-boosted regime, in which the products of the <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \mathrm{H}\to \mathrm{b}\overline{\mat
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Journal articleBelyaev A, Gevorgyan A, Hayrapetyan A, et al., 2026,
Measurement of the top quark pair production cross section in PbPb collisions at $$ \sqrt{s_{\mathrm{NN}}}=5.36 $$ TeV
, Journal of High Energy Physics, Vol: 2026<jats:title> A <jats:sc>bstract</jats:sc> </jats:title> <jats:p> The inclusive cross section for top quark pair ( <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \mathrm{t}\overline{\mathrm{t}} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> </jats:alternatives> </jats:inline-formula> ) production in lead-lead (PbPb) collisions is reported for the first time at a center-of-mass energy per nucleon pair of 5.36 TeV. The analysis uses data corresponding to an integrated luminosity of 1.58 nb <jats:sup> <jats:italic>−</jats:italic> 1 </jats:sup> collected by the CMS experiment at the CERN LHC in 2023. The <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \mathrm{t}\overline{\mathrm{t}} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math>
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Journal articleGevorgyan A, Hayrapetyan A, Makarenko V, et al., 2026,
Search for Higgs boson pair production in the $$ \mathrm{b}\overline{\mathrm{b}}\mathrm{WW} $$ decay channel with two leptons in the final state using proton-proton collision data at $$ \sqrt{s}=13.6 $$ TeV
, Journal of High Energy Physics, Vol: 2026<jats:title> A <jats:sc>bstract</jats:sc> </jats:title> <jats:p> A search for Higgs boson pair production is presented, targeting final states where one Higgs boson decays to a bottom quark-antiquark pair and the other Higgs boson decays to two W bosons, both of which decay leptonically, to an electron or a muon, and a neutrino. For the first time, the search is conducted with proton-proton collision data from the LHC at <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \sqrt{s}=13.6 $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13.6</mml:mn> </mml:math> </jats:alternatives> </jats:inline-formula> TeV, recorded with the CMS detector in 2022 and 2023 and corresponding to an integrated luminosity of 62 fb <jats:sup> <jats:italic>−</jats:italic> 1 </jats:sup> . The results are consistent with the standard model predictions. An upper limit of 12 <jats:italic>.</jats:italic> 0 times the standard model prediction at 95% confidence level is set on the Higgs boson pair production cross section, with an expected limit of 18 <jats:italic>.</jats:italic> 5. The results are also used to constrain the strength of the trilinear self-
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Journal articleAaij R, Abdelfatah M, Abdelmotteleb ASW, et al., 2026,
Angular analysis of the B+→ π+μ+μ− decay
, Journal of High Energy Physics, Vol: 2026This paper presents the first measurement of the forward-backward asymmetry, A<inf>FB</inf>, and the flat term, F<inf>H</inf>, that parameterise the angular distribution of the B<sup>+</sup> → π<sup>+</sup>μ<sup>+</sup>μ<sup>−</sup> decay. The proton-proton collision dataset used in the analysis corresponds to an integrated luminosity of 9 fb<sup>−1</sup>, collected with the LHCb experiment between 2011 and 2018. The analysis is performed in two intervals of dimuon mass squared, one above and one below the region containing the J/ψ and ψ(2S) narrow charmonium resonances. The Standard Model predictions lie within the obtained 68% confidence level interval in the high-mass and within the 99% interval in the low-mass region.
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Journal articleAaij R, Abdelfatah M, Abdelmotteleb ASW, et al., 2026,
Measurement of γ using B±→ DK± and B±→ Dπ± decays with D→KS0π+π− and D→KS0K+K−
, Journal of High Energy Physics, Vol: 2026A measurement of the CKM angle γ using the decay channels B<sup>±</sup>→ DK<sup>±</sup> and B<sup>±</sup>→ Dπ<sup>±</sup>, where the D meson decays to D→KS0π+π− or D→KS0K+K−, is performed with a data sample corresponding to an integrated luminosity of 5.8 fb<sup>−1</sup>, collected during 2024 by the upgraded LHCb experiment. CP violation is observed through a difference in the distributions of the Dalitz plot of the D decay between the B<sup>+</sup> and B<sup>−</sup> mesons. The CKM angle γ is determined to be γ = (68.1 ± 6.7)°. Other parameters related to the examined B meson decay modes are also measured. This is the first measurement of the CKM angle γ using the upgraded LHCb detector.
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