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1. Search for leptoquark pair production decaying into $$te^- \bar{t}e^+$$ or $$t\mu ^- \bar{t}\mu ^+$$ in multi-lepton final states in pp collisions at $$\sqrt{s} = 13\,\textrm{TeV}$$ with the ATLAS detector

   https://doi.org/10.1140/epjc/s10052-024-12975-4  

   Aad, G; Abbott, B; Abbott, D C; Abeling, K; Abidi, S H; Aboulhorma, A; Abramowicz, H; Abreu, H; Abulaiti, Y; Hoffman, A_C Abusleme; et al (August 2024, The European Physical Journal C)

   Abstract A search for leptoquark pair production decaying into$$te^- \bar{t}e^+$$ $t{e}^{-}\overline{t}{e}^{+}$or$$t\mu ^- \bar{t}\mu ^+$$ $t{\mu }^{-}\overline{t}{\mu }^{+}$in final states with multiple leptons is presented. The search is based on a dataset ofppcollisions at$$\sqrt{s}=13~\text {TeV} $$ $\sqrt{s}=13\text{TeV}$recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb$$^{-1}$$ $_{}^{-1}$. Four signal regions, with the requirement of at least three light leptons (electron or muon) and at least two jets out of which at least one jet is identified as coming from ab-hadron, are considered based on the number of leptons of a given flavour. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No excess above the Standard Model background prediction is observed and 95% confidence level limits on the production cross section times branching ratio are derived as a function of the leptoquark mass. Under the assumption of exclusive decays into$$te^{-}$$ $t{e}^{-}$($$t\mu ^{-}$$ $t{\mu }^{-}$), the corresponding lower limit on the scalar mixed-generation leptoquark mass$$m_{\textrm{LQ}_{\textrm{mix}}^{\textrm{d}}}$$ $m_{{\text{LQ}}_{\text{mix}}^{\text{d}}}$is at 1.58 (1.59) TeV and on the vector leptoquark mass$$m_{{\tilde{U}}_1}$$ $m_{{\tilde{U}}_1}$at 1.67 (1.67) TeV in the minimal coupling scenario and at 1.95 (1.95) TeV in the Yang–Mills scenario. 

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2. Differential cross-section measurements of Higgs boson production in the H → τ+τ− decay channel in pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector

   https://doi.org/10.1007/JHEP03(2025)010  

   Aad, G; Aakvaag, E; Abbott, B; Abdelhameed, S; Abeling, K; Abicht, N J; Abidi, S H; Aboelela, M; Aboulhorma, A; Abramowicz, H; et al (March 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> Differential measurements of Higgs boson production in theτ-lepton-pair decay channel are presented in the gluon fusion, vector-boson fusion (VBF),VHand$$ t\overline{t}H $$ $t\overline{t}H$associated production modes, with particular focus on the VBF production mode. The data used to perform the measurements correspond to 140 fb⁻¹of proton-proton collisions collected by the ATLAS experiment at the LHC. Two methods are used to perform the measurements: theSimplified Template Cross-Section(STXS) approach and anUnfolded Fiducial Differentialmeasurement considering only the VBF phase space. For the STXS measurement, events are categorized by their production mode and kinematic properties such as the Higgs boson’s transverse momentum ($$ {p}_{\textrm{T}}^{\textrm{H}} $$ $p_T^H$), the number of jets produced in association with the Higgs boson, or the invariant mass of the two leading jets (m_jj). For the VBF production mode, the ratio of the measured cross-section to the Standard Model prediction form_jj> 1.5 TeV and$$ {p}_{\textrm{T}}^{\textrm{H}} $$ $p_T^H$> 200 GeV ($$ {p}_{\textrm{T}}^{\textrm{H}} $$ $p_T^H$< 200 GeV) is$$ {1.29}_{-0.34}^{+0.39} $$ ${1.29}_{-0.34}^{+0.39}$($$ {0.12}_{-0.33}^{+0.34} $$ ${0.12}_{-0.33}^{+0.34}$). This is the first VBF measurement for the higher-$$ {p}_{\textrm{T}}^{\textrm{H}} $$ $p_T^H$criteria, and the most precise for the lower-$$ {p}_{\textrm{T}}^{\textrm{H}} $$ $p_T^H$criteria. Thefiducialcross-section measurements, which only consider the kinematic properties of the event, are performed as functions of variables characterizing the VBF topology, such as the signed ∆ϕ_jjbetween the two leading jets. The measurements have a precision of 30%–50% and agree well with the Standard Model predictions. These results are interpreted in the SMEFT framework, and place the strongest constraints to date on the CP-odd Wilson coefficient$$ {c}_{H\overset{\sim }{W}} $$ $c_{H\tilde{W}}$. 

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3. Bottom quark energy loss and hadronization with B+ and $$ {\textrm{B}}_{\textrm{s}}^0 $$ nuclear modification factors using pp and PbPb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ = 5.02 TeV

   https://doi.org/10.1007/JHEP02(2025)195  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Hussain, P S; Jeitler, M; et al (February 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> The production cross sections of$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$and B⁺mesons are reported in proton-proton (pp) collisions recorded by the CMS experiment at the CERN LHC with a center-of-mass energy of 5.02 TeV. The data sample corresponds to an integrated luminosity of 302 pb⁻¹. The cross sections are based on measurements of the$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$→J/ψ(μ⁺μ⁻)ϕ(1020)(K⁺K⁻) and B⁺→J/ψ(μ⁺μ⁻)K⁺decay channels. Results are presented in the transverse momentum (p_T) range 7–50 GeV/cand the rapidity interval |y|<2.4 for the B mesons. The measuredp_T-differential cross sections of B⁺and$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$in pp collisions are well described by fixed-order plus next-to-leading logarithm perturbative quantum chromodynamics calculations. Using previous PbPb collision measurements at the same nucleon-nucleon center-of-mass energy, the nuclear modification factors,R_AA, of the B mesons are determined. Forp_T>10 GeV/c, both mesons are found to be suppressed in PbPb collisions (withR_AAvalues significantly below unity), with less suppression observed for the$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$mesons. In thisp_Trange, theR_AAvalues for the B⁺mesons are consistent with those for inclusive charged hadrons and D⁰mesons. Below 10 GeV/c, both B⁺and$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$are found to be less suppressed than either inclusive charged hadrons or D⁰mesons, with the$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$R_AAvalue consistent with unity. TheR_AAvalues found for the B⁺and$$ {\textrm{B}}_{\textrm{s}}^0 $$ $B_s^0$are compared to theoretical calculations, providing constraints on the mechanism of bottom quark energy loss and hadronization in the quark-gluon plasma, the hot and dense matter created in ultrarelativistic heavy ion collisions. 

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4. Measurement of the $$ \textrm{t}\overline{\textrm{t}}\textrm{H} $$ and tH production rates in the H → $$ \textrm{b}\overline{\textrm{b}} $$ decay channel using proton-proton collision data at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP02(2025)097  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Hussain, P S; Jeitler, M; et al (February 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> An analysis of the production of a Higgs boson (H) in association with a top quark-antiquark pair ($$ \textrm{t}\overline{\textrm{t}}\textrm{H} $$ $t\overline{t}H$) or a single top quark (tH) is presented. The Higgs boson decay into a bottom quark-antiquark pair (H →$$ \textrm{b}\overline{\textrm{b}} $$ $b\overline{b}$) is targeted, and three different final states of the top quark decays are considered, defined by the number of leptons (electrons or muons) in the event. The analysis utilises proton-proton collision data collected at the CERN LHC with the CMS experiment at$$ \sqrt{s} $$ $\sqrt{s}$= 13 TeV in 2016–2018, which correspond to an integrated luminosity of 138 fb⁻¹. The observed$$ \textrm{t}\overline{\textrm{t}}\textrm{H} $$ $t\overline{t}H$production rate relative to the standard model expectation is 0.33 ± 0.26 = 0.33 ± 0.17(stat) ± 0.21(syst). Additionally, the$$ \textrm{t}\overline{\textrm{t}}\textrm{H} $$ $t\overline{t}H$production rate is determined in intervals of Higgs boson transverse momentum. An upper limit at 95% confidence level is set on the tH production rate of 14.6 times the standard model prediction, with an expectation of$$ {19.3}_{-6.0}^{+9.2} $$ ${19.3}_{-6.0}^{+9.2}$. Finally, constraints are derived on the strength and structure of the coupling between the Higgs boson and the top quark from simultaneous extraction of the$$ \textrm{t}\overline{\textrm{t}}\textrm{H} $$ $t\overline{t}H$and tH production rates, and the results are combined with those obtained in other Higgs boson decay channels. 

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5. Measurement of beauty-quark production in pp collisions at $$ \sqrt{s} $$ = 13 TeV via non-prompt D mesons

   https://doi.org/10.1007/JHEP10(2024)110  

   Acharya, S; Adamová, D; Agarwal, A; Aglieri_Rinella, G; Aglietta, L; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; et al (October 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> Thep_T-differential production cross sections of non-prompt D⁰, D⁺, and$$ {\textrm{D}}_{\textrm{s}}^{+} $$ $D_s^{+}$mesons originating from beauty-hadron decays are measured in proton–proton collisions at a centre-of-mass energy$$ \sqrt{s} $$ $\sqrt{s}$= 13 TeV. The measurements are performed at midrapidity, |y|<0.5, with the data sample collected by ALICE from 2016 to 2018. The results are in agreement with predictions from several perturbative QCD calculations. The fragmentation fraction of beauty quarks to strange mesons divided by the one to non-strange mesons,f_s/(f_u+f_d), is found to be 0.114 ± 0.016 (stat.) ± 0.006 (syst.) ± 0.003 (BR) ± 0.003 (extrap.). This value is compatible with previous measurements at lower centre-of-mass energies and in different collision systems in agreement with the assumption of universality of fragmentation functions. In addition, the dependence of the non-prompt D meson production on the centre-of-mass energy is investigated by comparing the results obtained at$$ \sqrt{s} $$ $\sqrt{s}$= 5.02 and 13 TeV, showing a hardening of the non-prompt D-mesonp_T-differential production cross section at higher$$ \sqrt{s} $$ $\sqrt{s}$. Finally, the$$ \textrm{b}\overline{\textrm{b}} $$ $b\overline{b}$production cross section per unit of rapidity at midrapidity is calculated from the non-prompt D⁰, D⁺,$$ {\textrm{D}}_{\textrm{s}}^{+} $$ $D_s^{+}$, and$$ {\Lambda}_{\textrm{c}}^{+} $$ ${\Lambda }_c^{+}$hadron measurements, obtaining$$ \textrm{d}\sigma /\textrm{d}y=75.2\pm 3.2\left(\textrm{stat}.\right)\pm 5.2{\left(\textrm{syst}.\right)}_{-3.2}^{+12.3}\left(\textrm{extrap}.\right) $$ $d\sigma /dy=75.2\pm 3.2\left(\text{stat}.\right)\pm 5.2{\left(\text{syst}.\right)}_{-3.2}^{+12.3}\left(\text{extrap}.\right)$μb. 

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