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A search for hidden-charm pentaquark states decaying to a range of${\mathrm{\Sigma }}_c\overline{D}$and${\mathrm{\Lambda }}_c^{+}\overline{D}$final states, as well as doubly charmed pentaquark states to${\mathrm{\Sigma }}_{c}D$and${\mathrm{\Lambda }}_c^{+}D$, is made using samples of proton-proton collision data corresponding to an integrated luminosity of$5.7{\mathrm{fb}}^{-1}$recorded by the LHCb detector at$\sqrt{s}=13\mathrm{TeV}$. Since no significant signals are found, upper limits are set on the pentaquark yields relative to that of the${\mathrm{\Lambda }}_c^{+}$baryon in the${\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+}$decay mode. The known pentaquark states are also investigated, and their signal yields are found to be consistent with zero in all cases.

A search for the fully reconstructed$$ {B}_s^0 $$$B_s^0$→ μ⁺μ⁻γdecay is performed at the LHCb experiment using proton-proton collisions at$$ \sqrt{s} $$$\sqrt{s}$= 13 TeV corresponding to an integrated luminosity of 5.4 fb⁻¹. No significant signal is found and upper limits on the branching fraction in intervals of the dimuon mass are set$$ {\displaystyle \begin{array}{cc}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[2{m}_{\mu },1.70\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<7.7\times {10}^{-8},&\ m\left({\mu}^{+}{\mu}^{-}\right)\in \left[\textrm{1.70,2.88}\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[3.92,{m}_{B_s^0}\right]\textrm{GeV}/{c}^2,\end{array}} $$$\begin{array}{cc}B\left(B_s^0\to {\mu }^{+}{\mu }^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu }^{+}{\mu }^{-}\right)\in \left(2m_{\mu },1.70\right)\mathrm{GeV}/c^2,\\ B\left(B_s^0\to {\mu }^{+}{\mu }^{-}\gamma \right)<7.7\times {10}^{-8},& m\left({\mu }^{+}{\mu }^{-}\right)\in \left(\mathrm{1.70,\; 2.88}\right)\mathrm{GeV}/c^2,\\ B\left(B_s^0\to {\mu }^{+}{\mu }^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu }^{+}{\mu }^{-}\right)\in \left(3.92,m_{B_s^0}\right)\mathrm{GeV}/c^2,\end{array}$

at 95% confidence level. Additionally, upper limits are set on the branching fraction in the [2m_μ,1.70] GeV/c²dimuon mass region excluding the contribution from the intermediateϕ(1020) meson, and in the region combining all dimuon-mass intervals.

A search for beyond the standard model spin-0 bosons,$\varphi$, that decay into pairs of electrons, muons, or tau leptons is presented. The search targets the associated production of such bosons with a$W$or$Z$gauge boson, or a top quark-antiquark pair, and uses events with three or four charged leptons, including hadronically decaying tau leptons. The proton-proton collision data set used in the analysis was collected at the LHC from 2016 to 2018 at a center-of-mass energy of 13 TeV, and corresponds to an integrated luminosity of$138{\mathrm{fb}}^{-1}$. The observations are consistent with the predictions from standard model processes. Upper limits are placed on the product of cross sections and branching fractions of such new particles over the mass range of 15 to 350 GeV with scalar, pseudoscalar, or Higgs-boson-like couplings, as well as on the product of coupling parameters and branching fractions. Several model-dependent exclusion limits are also presented. For a Higgs-boson-like$\varphi$model, limits are set on the mixing angle of the Higgs boson with the$\varphi$boson. For the associated production of a$\varphi$boson with a top quark-antiquark pair, limits are set on the coupling to top quarks. Finally, limits are set for the first time on a fermiophilic dilaton-like model with scalar couplings and a fermiophilic axion-like model with pseudoscalar couplings.

Measurements of inclusive charged-particle jet production in pp and p-Pb collisions at center-of-mass energy per nucleon-nucleon collision$$ \sqrt{s_{\textrm{NN}}} $$$\sqrt{s_{\mathrm{NN}}}$= 5.02 TeV and the corresponding nuclear modification factor$$ {R}_{\textrm{pPb}}^{\textrm{ch}\ \textrm{jet}} $$$R_{\mathrm{pPb}}^{\mathrm{ch}\mathrm{jet}}$are presented, using data collected with the ALICE detector at the LHC. Jets are reconstructed in the central rapidity region |η_jet|<0.5 from charged particles using the anti-k_Talgorithm with resolution parametersR= 0.2, 0.3, and 0.4. Thep_T-differential inclusive production cross section of charged-particle jets, as well as the corresponding cross section ratios, are reported for pp and p-Pb collisions in the transverse momentum range 10<$$ {p}_{\textrm{T},\textrm{jet}}^{\textrm{ch}} $$$p_{T,\mathrm{jet}}^{\mathrm{ch}}$<140 GeV/cand 10<$$ {p}_{\textrm{T},\textrm{jet}}^{\textrm{ch}} $$$p_{T,\mathrm{jet}}^{\mathrm{ch}}$<160 GeV/c, respectively, together with the nuclear modification factor$$ {R}_{\textrm{pPb}}^{\textrm{ch}\ \textrm{jet}} $$$R_{\mathrm{pPb}}^{\mathrm{ch}\mathrm{jet}}$in the range 10<$$ {p}_{\textrm{T},\textrm{jet}}^{\textrm{ch}} $$$p_{T,\mathrm{jet}}^{\mathrm{ch}}$<140 GeV/c. The analysis extends thep_Trange of the previously-reported charged-particle jet measurements by the ALICE Collaboration. The nuclear modification factor is found to be consistent with one and independent of the jet resolution parameter with the improved precision of this study, indicating that the possible influence of cold nuclear matter effects on the production cross section of charged-particle jets in p-Pb collisions at$$ \sqrt{s_{\textrm{NN}}} $$$\sqrt{s_{\mathrm{NN}}}$= 5.02 TeV is smaller than the current precision. The obtained results are in agreement with other minimum bias jet measurements available for RHIC and LHC energies, and are well reproduced by the NLO perturbative QCD Powhegcalculations with parton shower provided by Pythia8 as well as by Jetscapesimulations.

Results on the transverse spherocity dependence of light-flavor particle production (π, K, p,ϕ, K^*0,$$ {\textrm{K}}_{\textrm{S}}^0 $$$K_S^0$, Λ, Ξ) at midrapidity in high-multiplicity pp collisions at$$ \sqrt{s} $$$\sqrt{s}$= 13 TeV were obtained with the ALICE apparatus. The transverse spherocity estimator$$ \left({S}_{\textrm{O}}^{p_{\textrm{T}}=1}\right) $$$\left(S_O^{p_T=1}\right)$categorizes events by their azimuthal topology. Utilizing narrow selections on$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$$S_O^{p_T=1}$, it is possible to contrast particle production in collisions dominated by many soft initial interactions with that observed in collisions dominated by one or more hard scatterings. Results are reported for two multiplicity estimators covering different pseudorapidity regions. The$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$$S_O^{p_T=1}$estimator is found to effectively constrain the hardness of the events when the midrapidity (|η| < 0.8) estimator is used.

The production rates of strange particles are found to be slightly higher for soft isotropic topologies, and severely suppressed in hard jet-like topologies. These effects are more pronounced for hadrons with larger mass and strangeness content, and observed when the topological selection is done within a narrow multiplicity interval. This demonstrates that an important aspect of the universal scaling of strangeness enhancement with final-state multiplicity is that high-multiplicity collisions are dominated by soft, isotropic processes. On the contrary, strangeness production in events with jet-like processes is significantly reduced.

The results presented in this article are compared with several QCD-inspired Monte Carlo event generators. Models that incorporate a two-component phenomenology, either through mechanisms accounting for string density, or thermal production, are able to describe the observed strangeness enhancement as a function of$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$$S_O^{p_T=1}$.

The ALICE Collaboration reports a search for jet quenching effects in high-multiplicity (HM) proton-proton collisions at$$ \sqrt{s} $$$\sqrt{s}$= 13 TeV, using the semi-inclusive azimuthal-difference distribution ∆φof charged-particle jets recoiling from a high transverse momentum (high-p_T,trig) trigger hadron. Jet quenching may broaden the ∆φdistribution measured in HM events compared to that in minimum bias (MB) events. The measurement employs ap_T,trig-differential observable for data-driven suppression of the contribution of multiple partonic interactions, which is the dominant background. While azimuthal broadening is indeed observed in HM compared to MB events, similar broadening for HM events is observed for simulations based on the PYTHIA 8 Monte Carlo generator, which does not incorporate jet quenching. Detailed analysis of these data and simulations show that the azimuthal broadening is due to bias of the HM selection towards events with multiple jets in the final state. The identification of this bias has implications for all jet quenching searches where selection is made on the event activity.

$K^{+}{K}^{-}$pairs may be produced in photonuclear collisions, either from the decays of photoproduced$\varphi (1020)$mesons or directly as nonresonant$K^{+}{K}^{-}$pairs. Measurements of$K^{+}{K}^{-}$photoproduction probe the couplings between the$\varphi (1020)$and charged kaons with photons and nuclear targets. The kaon-proton scattering occurs at energies far above those available elsewhere. We present the first measurement of coherent photoproduction of$K^{+}{K}^{-}$pairs on lead ions in ultraperipheral collisions using the ALICE detector, including the first investigation of direct$K^{+}{K}^{-}$production. There is significant$K^{+}{K}^{-}$production at low transverse momentum, consistent with coherent photoproduction on lead targets. In the mass range$1.1<M_{KK}<1.4\mathrm{GeV}/c^2$above the$\varphi (1020)$resonance, for rapidity$|y_{KK}|<0.8$and$p_{T,KK}<0.1\mathrm{GeV}/c$, the measured coherent photoproduction cross section is$\mathrm{d}\sigma /\mathrm{d}y=3.37\pm 0.61(\text{stat})\pm 0.15(\mathrm{syst})\mathrm{mb}$. The center-of-mass energy per nucleon of the photon-nucleus (Pb) system$W_{\gamma \mathrm{Pb},n}$ranges from 33 to 188 GeV, far higher than previous measurements on heavy-nucleus targets. The cross section is larger than expected for$\varphi (1020)$photoproduction alone. The mass spectrum is fit to a cocktail consisting of$\varphi (1020)$decays, direct$K^{+}{K}^{-}$photoproduction, and interference between the two. The confidence regions for the amplitude and relative phase angle for direct$K^{+}{K}^{-}$photoproduction are presented.