We present searches for light dark matter (DM) with masses 3-9 GeV/$c^2$ in the presence of coherent elastic neutrino-nucleus scattering (CE$ν$NS) from $^{8}$B solar neutrinos with the LUX-ZEPLIN experiment. This analysis uses a 5.7 tonne-year 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 CE$ν$NS 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 CE$ν$NS events, corresponding to a $4.5σ$ statistical significance. This is the most significant evidence of $^{8}$B CE$ν$NS interactions and is enabled by robust background modeling and mitigation techniques. This demonstrates LZ's ability to detect rare signals at keV-scale energies.
90% CL WIMP SI cross sections, including sensitivities
90% CL WIMP SDn cross sections, including sensitivities and nuclear structure uncertainties
90% CL WIMP SDp cross sections, including sensitivities and nuclear structure uncertainties
The $pp \to W^{\pm} (\to μ^{\pm} ν_μ) X$ cross-sections are measured at a proton-proton centre-of-mass energy $\sqrt{s} = 5.02$ TeV using a dataset corresponding to an integrated luminosity of 100 pb$^{-1}$ recorded by the LHCb experiment. Considering muons in the pseudorapidity range $2.2 < η< 4.4$, the cross-sections are measured differentially in twelve intervals of muon transverse momentum between $28 < p_\mathrm{T} < 52$ GeV. Integrated over $p_\mathrm{T}$, the measured cross-sections are \begin{align*} σ_{W^+ \to μ^+ ν_μ} &= 300.9 \pm 2.4 \pm 3.8 \pm 6.0~\text{pb}, \\ σ_{W^- \to μ^- \barν_μ} &= 236.9 \pm 2.1 \pm 2.7 \pm 4.7~\text{pb}, \end{align*} where the first uncertainties are statistical, the second are systematic, and the third are associated with the luminosity calibration. These integrated results are consistent with theoretical predictions. This analysis introduces a new method to determine the $W$-boson mass using the measured differential cross-sections corrected for detector effects. The measurement is performed on this statistically limited dataset as a proof of principle and yields \begin{align*} m_W = 80369 \pm 130 \pm 33~\text{MeV}, \end{align*} where the first uncertainty is experimental and the second is theoretical.
The measured differential cross sections ($d\sigma/dp_T$) for $W^+$. The first systematic uncertainty is statistical and the second is systematic.
The measured differential cross sections ($d\sigma/dp_T$) for $W^-$. The first systematic uncertainty is statistical and the second is systematic.
The correlation matrix corresponding to the statistical uncertainties on the differential cross-section ($d\sigma/dp_T$) fit results for $W^+$. To combine with $W^-$, use the rows and columns ordered as $W^+$ and then $W^-$. Assume no correlation in the statistical uncertainties between $W^+$ and $W^-$ (zero entries in the off-diagonal blocks).
This article reports on a search for dijet resonances using $132$ fb$^{-1}$ of $pp$ collision data recorded at $\sqrt{s} = 13$ TeV by the ATLAS detector at the Large Hadron Collider. The search is performed solely on jets reconstructed within the ATLAS trigger to overcome bandwidth limitations imposed on conventional single-jet triggers, which would otherwise reject data from decays of sub-TeV dijet resonances. Collision events with two jets satisfying transverse momentum thresholds of $p_{\textrm{T}} \ge 85$ GeV and jet rapidity separation of $|y^{*}|<0.6$ are analysed for dijet resonances with invariant masses from $375$ to $1800$ GeV. A data-driven background estimate is used to model the dijet mass distribution from multijet processes. No significant excess above the expected background is observed. Upper limits are set at $95\%$ confidence level on coupling values for a benchmark leptophobic axial-vector $Z^{\prime}$ model and on the production cross-section for a new resonance contributing a Gaussian-distributed line-shape to the dijet mass distribution.
Observed $m_{jj}$ distribution for the J50 signal region, using variable-width bins and the analysis selections. The background estimate corresponds to the ansatz fit, integrated over each bin.
Observed $m_{jj}$ distribution for the J100 signal region, using variable-width bins and the analysis selections. The background estimate corresponds to the ansatz fit, integrated over each bin.
Observed 95% $\text{CL}_\text{S}$ upper limits on the production cross-section times acceptance times branching ratio to jets, $\sigma \cdot A \cdot \text{BR}$, of Gaussian-shaped signals of 5%, 10%, and 15% width relative to their peak mass, $m_G$. Also included are the corresponding expected upper limits predicted for the case the $m_{jj}$ distribution is observed to be identical to the background prediction in each bin and the $1\sigma$ and $2\sigma$ envelopes of outcomes expected for Poisson fluctuations around the background expectation. Limits are derived from the J50 signal region.
The measurement of $\Sigma^{+}$ production in pp collisions at $\sqrt{s} = 13$ TeV is presented. The measurement is performed at midrapidity in both minimum-bias and high-multiplicity pp collisions at $\sqrt{s} = 13$ TeV. The $\Sigma^{+}$ is reconstructed via its weak-decay topology in the decay channel $\Sigma^{+} \rightarrow {p} + \pi^{0}$ with $\pi^{0} \rightarrow \gamma + \gamma$. In a novel approach, the neutral pion is reconstructed by combining photons that convert in the detector material with photons measured in the calorimeters. The transverse-momentum ($p_{T}$) distributions of the $\Sigma^{+}$ and its rapidity densities d$N/$dy in both event classes are reported. The $p_{T}$ spectrum in minimum-bias collisions is compared to QCD-inspired event generators. The ratio of $\Sigma^{+}$ to previously measured $\Lambda$ baryons is in good agreement with calculations from the Statistical Hadronization Model. The high efficiency and purity of the novel reconstruction method for $\Sigma^{+}$ presented here will enable future studies of the interaction of $\Sigma^{+}$ with protons in the context of femtoscopic measurements, which could be crucial for understanding the equation of state of neutron stars.
$p_\mathrm{T}$-differential production yield of $\Sigma^+$ and $\bar{\Sigma}^-$ baryons in the high-multiplicity triggered pp collisions at $\sqrt{{s}}=13~\mathrm{{TeV}}$ in the rapidity interval $|y|<0.8$.
$p_\mathrm{T}$-differential production yield of $\Sigma^+$ and $\bar{\Sigma}^-$ baryons in the minimum-bias triggered pp collisions at $\sqrt{{s}}=13~\mathrm{{TeV}}$ in the rapidity interval $|y|<0.8$.
A model-agnostic search for Beyond the Standard Model physics is presented, targeting final states with at least four light leptons (electrons or muons). The search regions are separated by event topology and unsupervised machine learning is used to identify anomalous events in the full 140 fb$^{-1}$ of proton-proton collision data collected with the ATLAS detector during Run 2. No significant excess above the Standard Model background expectation is observed. Model-agnostic limits are presented in each topology, along with limits on several benchmark models including vector-like leptons, wino-like charginos and neutralinos, or smuons. Limits are set on the flavourful vector-like lepton model for the first time.
Comparison between data and the background prediction for the (a) m<sub>T</sub>(4ℓ, E<sub>T</sub><sup>miss</sup>), (b) m<sup>high</sup>(3ℓ), (c) m(Z), (d) E<sub>T</sub><sup>miss</sup>, (e) p<sub>T</sub>(Z), and (f) N<sub>jets</sub> distribution in the (a, d) 2Z 0b, (b, e) 1Z 1b 2SFOS, and (c, f) 0Z 2SFOS region, after requiring the anomaly score to be below the 90% background rejection point. The background contributions after the likelihood fit to data ('post-fit') for the background-only hypothesis are shown as filled histograms. The 'tt+X' background component includes the tt̄Z, and tt̄H processes. The 'HF ℓ' ('LF ℓ') background component refers to processes containing one non-prompt light lepton from heavy-flavour (light-flavour) hadron decays. The ratio of the data to the background prediction ('Bkg.') is shown in the lower panel. The 'Other' contribution is dominated by the tWZ production. The size of the combined statistical and systematic uncertainty in the background prediction is indicated by the blue hatched band. The upward-pointing blue arrows indicate points for which the data-to-background ('Data/Bkg.’) ratio exceeds the vertical range of the figure. The last bin contains the overflow.
Comparison between data and the background prediction for the (a) m<sub>T</sub>(4ℓ, E<sub>T</sub><sup>miss</sup>), (b) m<sup>high</sup>(3ℓ), (c) m(Z), (d) E<sub>T</sub><sup>miss</sup>, (e) p<sub>T</sub>(Z), and (f) N<sub>jets</sub> distribution in the (a, d) 2Z 0b, (b, e) 1Z 1b 2SFOS, and (c, f) 0Z 2SFOS region, after requiring the anomaly score to be below the 90% background rejection point. The background contributions after the likelihood fit to data ('post-fit') for the background-only hypothesis are shown as filled histograms. The 'tt+X' background component includes the tt̄Z, and tt̄H processes. The 'HF ℓ' ('LF ℓ') background component refers to processes containing one non-prompt light lepton from heavy-flavour (light-flavour) hadron decays. The ratio of the data to the background prediction ('Bkg.') is shown in the lower panel. The 'Other' contribution is dominated by the tWZ production. The size of the combined statistical and systematic uncertainty in the background prediction is indicated by the blue hatched band. The upward-pointing blue arrows indicate points for which the data-to-background ('Data/Bkg.’) ratio exceeds the vertical range of the figure. The last bin contains the overflow.
Comparison between data and the background prediction for the (a) m<sub>T</sub>(4ℓ, E<sub>T</sub><sup>miss</sup>), (b) m<sup>high</sup>(3ℓ), (c) m(Z), (d) E<sub>T</sub><sup>miss</sup>, (e) p<sub>T</sub>(Z), and (f) N<sub>jets</sub> distribution in the (a, d) 2Z 0b, (b, e) 1Z 1b 2SFOS, and (c, f) 0Z 2SFOS region, after requiring the anomaly score to be below the 90% background rejection point. The background contributions after the likelihood fit to data ('post-fit') for the background-only hypothesis are shown as filled histograms. The 'tt+X' background component includes the tt̄Z, and tt̄H processes. The 'HF ℓ' ('LF ℓ') background component refers to processes containing one non-prompt light lepton from heavy-flavour (light-flavour) hadron decays. The ratio of the data to the background prediction ('Bkg.') is shown in the lower panel. The 'Other' contribution is dominated by the tWZ production. The size of the combined statistical and systematic uncertainty in the background prediction is indicated by the blue hatched band. The upward-pointing blue arrows indicate points for which the data-to-background ('Data/Bkg.’) ratio exceeds the vertical range of the figure. The last bin contains the overflow.
The first measurement at midrapidity ($|y| < 0.5$) of the production yield of the strange-charm baryons $Ξ_c^+$ and $Ξ_c^0$ as a function of charged-particle multiplicity in proton-proton collisions at $\sqrt{s} = 13$ TeV with the ALICE experiment at the LHC is reported. The $Ξ_c^+$ baryon is reconstructed via the $Ξ_c^+ \rightarrow Ξ^-π^+π^+$ decay channel in the range $4 < p_{\rm T} < 12$ GeV/$c$, while the $Ξ_c^0$ baryon is reconstructed via both the $Ξ_c^0 \rightarrow Ξ^-π^+$ and $Ξ_c^0 \rightarrow Ξ^-e^+ν_e$ decay channels in the range $2 < p_{\rm T} < 12$ GeV/$c$. The baryon-to-meson ($Ξ_c^{0,+}/D^0$) and the baryon-to-baryon ($Ξ_c^{0,+}/Λ_c^+$) production yield ratios show no significant dependence on multiplicity. In addition, the observed yield ratios are not described by theoretical predictions that model charm-quark fragmentation based on measurements at $e^+e^-$ and $e^-$p colliders, indicating differences in the charm-baryon production mechanism in pp collisions. A comparison with different event generators and tunings, including different modelling of the hadronisation process, is also discussed. Moreover, the branching-fraction ratio of BR($Ξ_c^0 \rightarrow Ξ^-e^+ν_e$)/BR($Ξ_c^0 \rightarrow Ξ^-π^+$) is measured as 0.825 $\pm$ 0.094 (stat.) $\pm$ 0.081 (syst.). This value supersedes the previous ALICE measurement, improving the statistical precision by a factor of 1.6.
$p_{\rm T}$-differential per-event yield of prompt $\Xi_c^0$ baryons measured in the different multiplicity classes.
$p_{\rm T}$-differential per-event yield of prompt $\Xi_c^+$ baryons measured in the different multiplicity classes.
Ratio between the prompt $\Xi_c^0$ baryons in a multiplicity class to the multiplicity-integrated (INEL $>$ 0) class.
The transverse momentum spectra and integrated yields of $\overlineΣ^{\pm}$ have been measured in pp and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV with the ALICE experiment. Measurements are performed via the newly accessed decay channel $\overlineΣ^{\pm} \rightarrow {\rm\overline{n}}π^{\pm}$. A new method of antineutron reconstruction with the PHOS electromagnetic spectrometer is developed and applied to this analysis. The $p_{\rm T}$ spectra of $\overlineΣ^{\pm}$ are measured in the range $0.5 < p_{\rm T} < 3$ GeV/$c$ and compared to predictions of the PYTHIA 8, DPMJET, PHOJET, EPOS LHC and EPOS4 models. The EPOS LHC and EPOS4 models provide the best descriptions of the measured spectra both in pp and p-Pb collisions, while models which do not account for multiparton interactions provide a considerably worse description at high $p_{\rm T}$. The total yields of $\overlineΣ^{\pm}$ in both pp and p-Pb collisions are compared to predictions of the Thermal-FIST model and dynamical models PYTHIA 8, DPMJET, PHOJET, EPOS LHC and EPOS4. All models reproduce the total yields in both colliding systems within uncertainties. The nuclear modification factors $R_{\rm pPb}$ for both $\overlineΣ^{+}$ and $\overlineΣ^{-}$ are evaluated and compared to those of protons, $Λ$ and $Ξ$ hyperons, and predictions of EPOS LHC and EPOS4 models. No deviations of $R_{\rm pPb}$ for $\overlineΣ^{\pm}$ from the model predictions or measurements for other hadrons are found within uncertainties.
$p_\mathrm{{T}}$-differential production yield of $\overline{\Sigma}^{+}$ in INEL pp collisions at $\sqrt{s}=5.02~\mathrm{{TeV}}$ in the rapidity interval $|y|<0.5$.
$p_\mathrm{{T}}$-differential production yield of $\overline{\Sigma}^{-}$ in INEL pp collisions at $\sqrt{s}=5.02~\mathrm{{TeV}}$ in the rapidity interval $|y|<0.5$.
$p_\mathrm{{T}}$-differential production yield of $\overline{\Sigma}^{+}$ in NSD p-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02~\mathrm{{TeV}}$ in the rapidity interval $|y_\mathrm{CMS}|<0.5$.
We recently measured the branching fraction of the $B^{+}\rightarrow K^{+}ν\barν$ decay using 362fb$^{-1}$ of on-resonance $e^+e^-$ collision data under the assumption of Standard Model kinematics, providing the first evidence for this decay. To facilitate future reinterpretations and maximize the scientific impact of this measurement, we publicly release the full analysis likelihood along with all necessary material required for reinterpretation under arbitrary theoretical models sensitive to this measurement. In this work, we demonstrate how the measurement can be reinterpreted within the framework of the Weak Effective Theory. Using a kinematic reweighting technique in combination with the published likelihood, we derive marginal posterior distributions for the Wilson coefficients, construct credible intervals, and assess the goodness of fit to the Belle II data. For the Weak Effective Theory Wilson coefficients, the posterior mode of the magnitudes $|C_\mathrm{VL}+C_\mathrm{VR}|$, $|C_\mathrm{SL}+C_\mathrm{SR}|$, and $|C_\mathrm{TL}|$ corresponds to the point ${(11.3, 0.0, 8.2)}$. The respective 95% credible intervals are $[1.9, 16.2]$, $[0.0, 15.4]$, and $[0.0, 11.2]$.
The joint number density useful for reinterpretation in terms of new physics models (https://arxiv.org/abs/2402.08417). This is a 2d histogram of the ITA signal samples, combining both regions B (bins of $\eta(\rm{BDT}_2) \in [0.92, 0.94]$), binned in the kinematic variable $q^{2}_{\rm{gen}}$ and the fitting variables $q^{2}_{\rm{rec}} \times \eta(\rm{BDT}_2)$ (flattened).
The joint number density useful for reinterpretation in terms of new physics models (https://arxiv.org/abs/2402.08417). This is a 2d histogram of the HTA signal samples, binned in the kinematic variable $q^{2}_{\rm{gen}}$ and the fitting variable $\eta(\rm{BDTh})$.
The PHENIX experiment at the Relativistic Heavy Ion Collider has measured low-mass vector-meson ($ω+ρ$ and $ϕ$) production through the dimuon decay channel at forward rapidity $(1.2<|\mbox{y}|<2.2)$ in $p$$+$$p$ and Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$~GeV. The low-mass vector-meson yield and nuclear-modification factor were measured as a function of the average number of participating nucleons, $\langle N_{\rm part}\rangle$, and the transverse momentum $p_T$. These results were compared with those obtained via the kaon decay channel in a similar $p_T$ range at midrapidity. The nuclear-modification factors in both rapidity regions are consistent within the uncertainties. A comparison of the $ω+ρ$ and $J/ψ$ mesons reveals that the light and heavy flavors are consistently suppressed across both $p_T$ and ${\langle}N_{\rm part}\rangle$. In contrast, the $ϕ$ meson displays a nuclear-modification factor consistent with unity, suggesting strangeness enhancement in the medium formed.
The differential cross sections of $\omega+\rho$ mesons as a function of $p_T$ in $p+p$ collisions. The systematic uncertainties of type-A (uncorrelated) are combined with statistical uncertainties in quadrature and are labeled as stat. Type-B (correlated) systematic uncertainties are listed as sys.
The differential cross sections of $\phi$ meson as a function of $p_T$ in $p+p$ collisions. The systematic uncertainties of type-A (uncorrelated) are combined with statistical uncertainties in quadrature and are labeled as stat. Type-B (correlated) systematic uncertainties are listed as sys.
The invariant yields of $\phi$ and $\omega+\rho$ mesons as a function of $p_T$ in Au+Au collisions. The systematic uncertainties of type-A (uncorrelated) are combined with statistical uncertainties in quadrature and are labeled as stat. Type-B (correlated) systematic uncertainties are listed as sys.
A search for Higgs boson pair production in the $b \overline{b} γγ$ final state is performed. The proton-proton collision dataset in this analysis corresponds to an integrated luminosity of 308 fb$^{-1}$, consisting of two samples, 140 fb$^{-1}$ at a centre-of-mass energy of 13 TeV and 168 fb$^{-1}$ at 13.6 TeV, recorded between 2015 and 2024 by the ATLAS detector at the CERN Large Hadron Collider. In addition to a larger dataset, this analysis improves upon the previous search in the same final state through several methodological and technical developments. The Higgs boson pair production cross section divided by the Standard Model prediction is found to be $μ_{HH} = 0.9^{+1.4}_{-1.1}$ ($μ_{HH} = 1^{+1.3}_{-1.0}$ expected), which translates into a 95% confidence-level upper limit of $μ_{HH}<3.8$. At the same confidence level the Higgs self-coupling modifier is constrained to be in the range $-1.7 < κ_λ< 6.6$ ($-1.8 < κ_λ< 6.9$ expected).
Weighted di-photon invariant mass distribution summed over all categories and the two data-taking periods. The events in each category are weighted by $log(1+S_{SM}/B)$. $S_{SM}$ is the expected signal yield assuming $\mu_{HH}$=1, while B is the continuum background yield obtained from a fit to the sidebands plus the single Higgs boson background obtained from simulation, all in a ± 5 GeV window around the Higgs boson mass. The lines show the fit results for the continuum background only (light dotted), adding single Higgs boson backgrounds (black dotted) and the full fit (solid).
Weighted di-photon invariant mass distribution summed over all categories and the two data-taking periods. The events in each category are weighted by $log(1+S_{SM}/B)$. $S_{SM}$ is the expected signal yield assuming $\mu_{HH}$=1, while B is the continuum background yield obtained from a fit to the sidebands plus the single Higgs boson background obtained from simulation, all in a ± 5 GeV window around the Higgs boson mass. The lines show the fit results for the continuum background only (light dotted), adding single Higgs boson backgrounds (black dotted) and the full fit (solid).
The 95% CL upper limits on the signal strength, obtained with separate fits to Run-2 and Run-3 data as well as their combination. When computing the significance or upper limit for one data-taking period only, $\mu_{HH}$ of the other period is left free to vary. All other parameters of interest are fixed to their SM expectation.
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