Additional spin-0 particles appear in many extensions of the standard model. We search for long-lived spin-0 particles $S$ in $B$-meson decays mediated by a $b\to s$ quark transition in $e^+e^-$ collisions at the $\Upsilon(4S)$ resonance at the Belle II experiment. Based on a sample corresponding to an integrated luminosity of $189 \mathrm{\,fb}^{-1}$, we observe no evidence for signal. We set model-independent upper limits on the product of branching fractions $\mathrm{Br}(B^0\to K^*(892)^0(\to K^+\pi^-)S)\times \mathrm{Br}(S\to x^+x^-)$ and $\mathrm{Br}(B^+\to K^+S)\times \mathrm{Br}(S\to x^+x^-)$, where $x^+x^-$ indicates $e^+e^-, \mu^+\mu^-, \pi^+\pi^-$, or $K^+K^-$, as functions of $S$ mass and lifetime at the level of $10^{-7}$.
Expected and observed candidates for $\mathcal{B}($$B^+\to K^+S$$) \times$ $\mathcal{B}($$S\to e^+e^-$) as a function of the reduced mediator candidate mass.
Expected and observed candidates for $\mathcal{B}($$B^+\to K^+S$$) \times$ $\mathcal{B}($$S\to \mu^+\mu^-$) as a function of the reduced mediator candidate mass.
Expected and observed candidates for $\mathcal{B}($$B^+\to K^+S$$) \times$ $\mathcal{B}($$S\to \pi^+\pi^-$) as a function of the reduced mediator candidate mass.
The cross section for coherent photonuclear production of J/$\psi$ is presented as a function of the electromagnetic dissociation (EMD) of Pb. The measurement is performed with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. Cross sections are presented in five different J/$\psi$ rapidity ranges within $|y|<4$, with the J/$\psi$ reconstructed via its dilepton decay channels. In some events the J/$\psi$ is not accompanied by EMD, while other events do produce neutrons from EMD at beam rapidities either in one or the other beam direction, or in both. The cross sections in a given rapidity range and for different configurations of neutrons from EMD allow for the extraction of the energy dependence of this process in the range $17 < W_{\gamma\, \mathrm{Pb, n}} <920$ GeV, where $W_{\gamma\, \mathrm{Pb, n}}$ is the centre-of-mass energy per nucleon of the $\gamma\,\mathrm{Pb}$ system. This range corresponds to a Bjorken-$x$ interval spanning about three orders of magnitude: $ 1.1\times10^{-5}
Measured coherent J/psi cross section for the 0N0N class. Note that for each rapidity range the 0n0n uncertainty related to migrations is preceded by a ∓, while the other neutron classes have a ±; this means that these uncertainties are anti-correlated.
Measured coherent J/psi cross section for the 0NXN+XN0N class. Note that for each rapidity range the 0n0n uncertainty related to migrations is preceded by a ∓, while the other neutron classes have a ±; this means that these uncertainties are anti-correlated.
Measured coherent J/psi cross section for the XN0N forward class. Note that for each rapidity range the 0n0n uncertainty related to migrations is preceded by a ∓, while the other neutron classes have a ±; this means that these uncertainties are anti-correlated.
A search for the lepton-flavor violating decay of the Higgs boson and potential additional Higgs bosons with a mass in the range 110-160 GeV to an e$^{\pm}\mu^{\mp}$ pair is presented. The search is performed with a proton-proton collision dataset at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. No excess is observed for the Higgs boson. The observed (expected) upper limit on the e$^{\pm}\mu^{\mp}$ branching fraction for it is determined to be 4.4 (4.7) $\times$ 10$^{-5}$ at 95% confidence level, the most stringent limit set thus far from direct searches. The largest excess of events over the expected background in the full mass range of the search is observed at an e$^{\pm}\mu^{\mp}$ invariant mass of approximately 146 GeV with a local (global) significance of 3.8 (2.8) standard deviations.
Observed (expected) 95% confidence level upper limits on $\mathcal{B}(H \to e \mu)$ for each individual analysis category (as shown in the left axis label) and for the combination of all analysis categories.
Observed (expected) 95% confidence level upper limits on $\sigma(p p \to X \to e \mu)$ as functions of the hypothesised $m_{X}$ assuming the relative SM-like production cross sections of the ggH and VBF production modes.
Observed local $\textit{p}$-values against the background-only hypothesis are shown as a function of the hypothesised $m_{X}$.
The second-order ($v_2$) and third-order ($v_3$) Fourier coefficients describing the azimuthal anisotropy of prompt and nonprompt (from b-hadron decays) J/$\psi$, as well as prompt $\psi$(2S) mesons are measured in lead-lead collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV. The analysis uses a data set corresponding to an integrated luminosity of 1.61 nb$^{-1}$ recorded with the CMS detector. The J/$\psi$ and $\psi$(2S) mesons are reconstructed using their dimuon decay channel. The $v_2$ and $v_3$ coefficients are extracted using the scalar product method and studied as functions of meson transverse momentum and collision centrality. The measured $v_2$ values for prompt J/$\psi$ mesons are found to be larger than those for nonprompt J/$\psi$ mesons. The prompt J/$\psi$$v_2$ values at high $p_\mathrm{T}$ are found to be underpredicted by a model incorporating only parton energy loss effects in a quark-gluon plasma medium. Prompt and nonprompt J/$\psi$ meson $v_3$ and prompt $\psi$(2S) $v_2$ and $v_3$ values are also reported for the first time, providing new information about heavy quark interactions in the hot and dense medium created in heavy ion collisions.
The $v_{2}$ values as functions of $p_{\text{T}}$ for prompt and nonprompt J/$\psi$ mesons in the 10–60% centrality range. The results for 3 $< p_{\text{T}} <$ 6.5 and 6.5 $< p_{\text{T}} <$ 50 GeV/c are studied in the rapidity range of 1.6 $< |y| <$ 2.4 and $|y| <$ 2.4, respectively.
The $v_{2}$ values as a function of centrality for prompt and nonprompt J/$\psi$ mesons. The kinematic range is 6.5 $< p_{\text{T}} <$ 50 GeV/c and $|y| <$ 2.4.
The $v_{3}$ values as functions of $p_{\text{T}}$ for prompt and nonprompt J/$\psi$ mesons in the 10–60% centrality range. The results for 3 $< p_{\text{T}} <$ 6.5 and 6.5 $< p_{\text{T}} <$ 50 GeV/c are studied in the rapidity range of 1.6 $< |y| <$ 2.4 and $|y| <$ 2.4, respectively.
This Letter reports the observation of $WZ\gamma$ production and a measurement of its cross-section using 140.1 $\pm$ 1.2 fb$^{-1}$ of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The $WZ\gamma$ production cross-section, with both the $W$ and $Z$ bosons decaying leptonically, $pp \rightarrow WZ\gamma \rightarrow {\ell'}^{\pm}\nu\ell^{+}\ell^{-}\gamma$ ($\ell^{(')} = e, \mu$), is measured in a fiducial phase-space region defined such that the leptons and the photon have high transverse momentum and the photon is isolated. The cross-section is found to be 2.01 $\pm$ 0.30 (stat.) $\pm$ 0.16 (syst) fb. The corresponding Standard Model predicted cross-section calculated at next-to-leading order in perturbative quantum chromodynamics and at leading order in the electroweak coupling constant is 1.50 $\pm$ 0.06 fb. The observed significance of the $WZ\gamma$ signal is 6.3$\sigma$, compared with an expected significance of 5.0$\sigma$.
Events in bins of the photon $p_{\mathrm{T}}^{\gamma}$ in the SR.
Events in bins of the $p_{\mathrm{T}}^{\ell_{1}}$ in the SR.
Events in bins of the $m(\ell\ell)$ in the SR.
A search for leptoquarks decaying into the $b\tau$ final state is performed using Run 2 proton-proton collision data from the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb$^{-1}$ at $\sqrt{s} = 13$ TeV recorded by the ATLAS detector. The benchmark models considered in this search are vector leptoquarks with electric charge of 2/3e and scalar leptoquarks with an electric charge of 4/3e. No significant excess above the Standard Model prediction is observed, and 95% confidence level upper limits are set on the cross-section times branching fraction of leptoquarks decaying into $b\tau$. For the vector leptoquark production two models are considered: the Yang-Mills and Minimal coupling models. In the Yang-Mills (Minimal coupling) scenario, vector leptoquarks with a mass below 1.58 (1.35) TeV are excluded for a gauge coupling of 1.0 and below 2.05 (1.99) TeV for a gauge coupling of 2.5. In the case of scalar leptoquarks, masses below 1.28 TeV (1.53 TeV) are excluded for a Yukawa coupling of 1.0 (2.5). Finally, an interpretation of the results with minimal model dependence is performed for each of the signal region categories, and limits on the visible cross-section for beyond the Standard Model processes are provided.
Observed (solid line) and expected (dashed line) 95% CL upper limits on the cross-section of single plus non-resonant plus pair vector LQ production from the combination of the high b-jet $p_{T}$ signal region for the $\tau_\text{lep}\tau_\text{had}$ and $\tau_\text{had}\tau_\text{had}$ channels. [$U_1^{YM}$ model ($\kappa$ = 0) with $\lambda$ = 1.0]
Observed (solid line) and expected (dashed line) 95% CL upper limits on the cross-section of single plus non-resonant plus pair vector LQ production from the combination of the high b-jet $p_{T}$ signal region for the $\tau_\text{lep}\tau_\text{had}$ and $\tau_\text{had}\tau_\text{had}$ channels. [$U_1^{YM}$ model ($\kappa$ = 0) with $\lambda$ = 1.7]
Observed (solid line) and expected (dashed line) 95% CL upper limits on the cross-section of single plus non-resonant plus pair vector LQ production from the combination of the high b-jet $p_{T}$ signal region for the $\tau_\text{lep}\tau_\text{had}$ and $\tau_\text{had}\tau_\text{had}$ channels. [$U_1^{YM}$ model ($\kappa$ = 0) with $\lambda$ = 2.5]
A search for dark matter produced in association with a Higgs boson in final states with two hadronically decaying $\tau$-leptons and missing transverse momentum is presented. The analysis uses $139$ fb$^{-1}$ of proton-proton collision data at $\sqrt{s}=13$ TeV collected by the ATLAS experiment at the Large Hadron Collider between 2015 and 2018. No evidence for physics beyond the Standard Model is found. The results are interpreted in terms of a 2HDM+$a$ model. Exclusion limits at 95% confidence level are derived. Model-independent limits are also set on the visible cross section for processes beyond the Standard Model producing missing transverse momentum in association with a Higgs boson decaying to $\tau$-leptons.
<b>- - - - - - - - Overview of HEPData Record - - - - - - - -</b> <br><br> <b>CLs and CLs+b values</b> <ul> <li><a href=?table=CLs_tanb_mA_grid_Expected>Expected CLs values in mA vs tanB grid, Low mA SR</a> <li><a href=?table=CLs_tanb_mA_grid_Observed>Observed CLs values in mA vs tanB grid, Low mA SR</a> <li><a href=?table=CLs_ma_mA_grid_HighmA_SR_Expected>Expected CLs values in mA vs ma grid, High mA SR</a> <li><a href=?table=CLs_ma_mA_grid_HighmA_SR_Observed>Observed CLs values in mA vs ma grid, High mA SR</a> <li><a href=?table=CLs_ma_mA_grid_LowmA_SR_Expected>Expected CLs values in mA vs ma grid, Low mA SR</a> <li><a href=?table=CLs_ma_mA_grid_LowmA_SR_Observed>Observed CLs values in mA vs ma grid, Low mA SR</a> <li><a href=?table=CLsplusb_tanb_mA_grid>CLs+b values in mA vs tanB grid, Low mA SR</a> <li><a href=?table=CLsplusb_ma_mA_grid_HighmA_SR>CLs+b values in mA vs ma grid, High mA SR</a> <li><a href=?table=CLsplusb_ma_mA_grid_LowmA_SR>CLs+b values in mA vs ma grid, Low mA SR</a> </ul> <b>Cutflow tables</b> <ul> <li><a href=?table=Cutflows_ggf_LowmA_SR>Low mA SR, ggF production</a> <li><a href=?table=Cutflows_ggf_HighmA_SR>High mA SR, ggF production</a> <li><a href=?table=Cutflows_bb_LowmA_SR>Low mA SR, bb production</a> <li><a href=?table=Cutflows_bb_HighmA_SR>High mA SR, bb production</a> </ul> <b>Kinematic Distributions</b> <ul> <li><a href=?table=KinDist_LowmA_SR>Low mA SR mTtau1+mTtau2 distribution</a> <li><a href=?table=KinDist_HighmA_SR>High mA SR mTtau1+mTtau2 distribution</a> </ul> <b>Limits</b> <ul> <li><a href=?table=Expected_95%_CL_exclusion_limit_mAma_grid>Expected 95% CL exclusion limit in mA vs ma grid</a> <li><a href=?table=Observed_95%_CL_exclusion_limit_mAma_grid>Observed 95% CL exclusion limit in mA vs ma grid</a> <li><a href=?table=Expected_pm1sigma_95%_CL_exclusion_limit_mAma_grid>Expected +-1 sigma 95% CL exclusion limit in mA vs ma grid</a> <li><a href=?table=Expected_95%_CL_exclusion_limit_mAtanB_grid>Expected 95% CL exclusion limit in mA vs tanB grid</a> <li><a href=?table=Observed_95%_CL_exclusion_limit_mAtanB_grid>Observed 95% CL exclusion limit in mA vs tanB grid</a> <li><a href=?table=Expected_pm1sigma_95%_CL_exclusion_limit_mAtanB_grid>Expected +-1 sigma 95% CL exclusion limit in tanB grid</a> </ul> <b>Acceptance and efficiency</b> <ul> <li><a href=?table=table1>Acceptance, High mA SR, mA vs tanB grid, 400-750 GeV, bb prod</a> <li><a href=?table=table2>Acceptance, High mA SR, mA vs tanB grid, >750 GeV, bb prod</a> <li><a href=?table=table3>Acceptance, Low mA SR, mA vs tanB grid, 100-250 GeV, bb prod</a> <li><a href=?table=table4>Acceptance, Low mA SR, mA vs tanB grid, 250-400 GeV, bb prod</a> <li><a href=?table=table5>Acceptance, Low mA SR, mA vs tanB grid, 400-550 GeV, bb prod</a> <li><a href=?table=table6>Acceptance, Low mA SR, mA vs tanB grid, >550 GeV, bb prod</a> <li><a href=?table=table7>Acceptance, High mA SR, mA vs ma grid, 400-750 GeV, bb prod</a> <li><a href=?table=table8>Acceptance, High mA SR, mA vs ma grid, >750 GeV, bb prod</a> <li><a href=?table=table9>Acceptance, Low mA SR, mA vs ma grid, 100-250 GeV, bb prod</a> <li><a href=?table=table10>Acceptance, Low mA SR, mA vs ma grid, 250-400 GeV, bb prod</a> <li><a href=?table=table11>Acceptance, Low mA SR, mA vs ma grid, 400-550 GeV, bb prod</a> <li><a href=?table=table12>Acceptance, Low mA SR, mA vs ma grid, >550 GeV, bb prod</a> <li><a href=?table=table13>Acceptance, High mA SR, mA vs tanB grid, 400-750 GeV, ggF prod</a> <li><a href=?table=table14>Acceptance, High mA SR, mA vs tanB grid, >750 GeV, ggF prod</a> <li><a href=?table=table15>Acceptance, Low mA SR, mA vs tanB grid, 100-250 GeV, ggF prod</a> <li><a href=?table=table16>Acceptance, Low mA SR, mA vs tanB grid, 250-400 GeV, ggF prod</a> <li><a href=?table=table17>Acceptance, Low mA SR, mA vs tanB grid, 400-550 GeV, ggF prod</a> <li><a href=?table=table18>Acceptance, Low mA SR, mA vs tanB grid, >550 GeV, ggF prod</a> <li><a href=?table=table19>Acceptance, High mA SR, mA vs ma grid, 400-750 GeV, ggF prod</a> <li><a href=?table=table20>Acceptance, High mA SR, mA vs ma grid, >750 GeV, ggF prod</a> <li><a href=?table=table21>Acceptance, Low mA SR, mA vs ma grid, 100-250 GeV, ggF prod</a> <li><a href=?table=table22>Acceptance, Low mA SR, mA vs ma grid, 250-400 GeV, ggF prod</a> <li><a href=?table=table23>Acceptance, Low mA SR, mA vs ma grid, 400-550 GeV, ggF prod</a> <li><a href=?table=table24>Acceptance, Low mA SR, mA vs ma grid, >550 GeV, ggF prod</a> <li><a href=?table=table25>Efficiency, High mA SR, mA vs tanB grid, 400-750 GeV, bb prod</a> <li><a href=?table=table26>Efficiency, High mA SR, mA vs tanB grid, >750 GeV, bb prod</a> <li><a href=?table=table27>Efficiency, Low mA SR, mA vs tanB grid, 100-250 GeV, bb prod</a> <li><a href=?table=table28>Efficiency, Low mA SR, mA vs tanB grid, 250-400 GeV, bb prod</a> <li><a href=?table=table29>Efficiency, Low mA SR, mA vs tanB grid, 400-550 GeV, bb prod</a> <li><a href=?table=table30>Efficiency, Low mA SR, mA vs tanB grid, >550 GeV, bb prod</a> <li><a href=?table=table31>Efficiency, High mA SR, mA vs ma grid, 400-750 GeV, bb prod</a> <li><a href=?table=table32>Efficiency, High mA SR, mA vs ma grid, >750 GeV, bb prod</a> <li><a href=?table=table33>Efficiency, Low mA SR, mA vs ma grid, 100-250 GeV, bb prod</a> <li><a href=?table=table34>Efficiency, Low mA SR, mA vs ma grid, 250-400 GeV, bb prod</a> <li><a href=?table=table35>Efficiency, Low mA SR, mA vs ma grid, 400-550 GeV, bb prod</a> <li><a href=?table=table36>Efficiency, Low mA SR, mA vs ma grid, >550 GeV, bb prod</a> <li><a href=?table=table37>Efficiency, High mA SR, mA vs tanB grid, 400-750 GeV, ggF prod</a> <li><a href=?table=table38>Efficiency, High mA SR, mA vs tanB grid, >750 GeV, ggF prod</a> <li><a href=?table=table39>Efficiency, Low mA SR, mA vs tanB grid, 100-250 GeV, ggF prod</a> <li><a href=?table=table40>Efficiency, Low mA SR, mA vs tanB grid, 250-400 GeV, ggF prod</a> <li><a href=?table=table41>Efficiency, Low mA SR, mA vs tanB grid, 400-550 GeV, ggF prod</a> <li><a href=?table=table42>Efficiency, Low mA SR, mA vs tanB grid, >550 GeV, ggF prod</a> <li><a href=?table=table43>Efficiency, High mA SR, mA vs ma grid, 400-750 GeV, ggF prod</a> <li><a href=?table=table44>Efficiency, High mA SR, mA vs ma grid, >750 GeV, ggF prod</a> <li><a href=?table=table45>Efficiency, Low mA SR, mA vs ma grid, 100-250 GeV, ggF prod</a> <li><a href=?table=table46>Efficiency, Low mA SR, mA vs ma grid, 250-400 GeV, ggF prod</a> <li><a href=?table=table47>Efficiency, Low mA SR, mA vs ma grid, 400-550 GeV, ggF prod</a> <li><a href=?table=table48>Efficiency, Low mA SR, mA vs ma grid, >550 GeV, ggF prod</a> </ul>
Expected CLs values in the Low mA SR, mA vs tanB signal grid.
Observed CLs values in the Low mA SR, mA vs tanB signal grid.
The observation of the production of four top quarks in proton-proton collisions is reported, based on a data sample collected by the CMS experiment at a center-of-mass energy of 13 TeV in 2016-2018 at the CERN LHC and corresponding to an integrated luminosity of 138 fb$^{-1}$. Events with two same-sign, three, or four charged leptons (electrons and muons) and additional jets are analyzed. Compared to previous results in these channels, updated identification techniques for charged leptons and jets originating from the hadronization of b quarks, as well as a revised multivariate analysis strategy to distinguish the signal process from the main backgrounds, lead to an improved expected signal significance of 4.9 standard deviations above the background-only hypothesis. Four top quark production is observed with a significance of 5.6 standard deviations, and its cross section is measured to be 17.7 $^{+3.7}_{-3.5}$ (stat) $^{+2.3}_{-1.9}$ (syst) fb, in agreement with the available standard model predictions.
Comparison of fit results in the channels individually and in their combination. The left panel shows the values of the measured cross section relative to the SM prediction from Ref. [6]. The right panel shows the expected and observed significance, with the printed values rounded to the first decimal.
Number of predicted and observed events in the SR-2$\ell$ and SR-3$\ell$ $t\bar{t}t\bar{t}$ classes, both before the fit to the data ("prefit") and with their best fit normalizations ("postfit"). The uncertainties in the predicted number of events include both the statistical and systematic components. The uncertainties in the total number of predicted background and background plus signal events are also given.
A search for dark matter in events with a displaced nonresonant muon pair and missing transverse momentum is presented. The analysis is performed using an integrated luminosity of 138 fb$^{-1}$ of proton-proton (pp) collision data at a center-of-mass energy of 13 TeV produced by the LHC in 2016-2018. No significant excess over the predicted backgrounds is observed. Upper limits are set on the product of the inelastic dark matter production cross section $\sigma$(pp $\to$ A' $\to$$\chi_1$$\chi_2$) and the decay branching fraction $\mathcal{B}$($\chi_2$$\to$$\chi_1 \mu^+ \mu^-$), where A' is a dark photon and $\chi_1$ and $\chi_2$ are states in the dark sector with near mass degeneracy. This is the first dedicated collider search for inelastic dark matter.
Definition of ABCD bins and yields in data, per match category. The predicted yield in the bin with the smallest backgrounds (bin D) is extracted from the simultaneous four-bin fit by assuming zero signal, which corresponds to $(\text{Obs. B} \times \text{Obs. C}) / (\text{Obs. A})$ in this limit.
Systematic uncertainties in the analysis. The jet uncertainties are larger in 2017 because of noise issues with the ECAL endcap. The tracking inefficiency in 2016 is caused by the unexpected saturation of photodiode signals in the tracker.
Simulated muon reconstruction efficiency of standard (blue squares) and displaced (red circles) reconstruction algorithms as a function of transverse vertex displacement $v_{xy}$. The two dashed vertical gray lines denote the ends of the fiducial tracker and muon detector regions, respectively.
A search for physics beyond the Standard Model inducing periodic signals in the dielectron and diphoton invariant mass spectra is presented using 139 fb$^{-1}$ of $\sqrt{s}=13$ TeV $pp$ collision data collected by the ATLAS experiment at the LHC. Novel search techniques based on continuous wavelet transforms are used to infer the frequency of periodic signals from the invariant mass spectra and neural network classifiers are used to enhance the sensitivity to periodic resonances. In the absence of a signal, exclusion limits are placed at the 95% confidence level in the two-dimensional parameter space of the clockwork gravity model. Model-independent searches for deviations from the background-only hypothesis are also performed.
The observed exclusion limit at 95% CL for the clockwork gravity model projected in the $k–M_{5}$ parameter space for the $ee$ channel for the case with mass thresholds.
The median expected exclusion limit at 95% CL for the clockwork gravity model projected in the $k–M_{5}$ parameter space for the $ee$ channel for the case with mass thresholds.
The expected plus one standard deviation exclusion limit at 95% CL for the clockwork gravity model projected in the $k–M_{5}$ parameter space for the $ee$ channel for the case with mass thresholds.