In the physics program of the CMS experiment during the CERN LHC Run 3, which started in 2022, the long-lived particle triggers have been improved and extended to expand the scope of the corresponding searches. These dedicated triggers and their performance are described in this paper, using several theoretical benchmark models that extend the standard model of particle physics. The results are based on proton-proton collision data collected with the CMS detector during 2022$-$2024 at a center-of-mass energy of 13.6 TeV, corresponding to integrated luminosities of up to 123 fb$^{-1}$.
Offline standard tracking efficiency during Run~3 for different tracking iterations, as a function of simulated radial position of the track production vertex. In the figure, $t\bar{t}$ simulation for 2025 conditions and an average PU of 62 is used, and the tracks are required to have $\mathrm{p_T}>0.9$ GeV and $|\eta|<2.5$. The tracking efficiency is defined as the ratio of the simulated tracks (with the aforementioned selection requirements) geometrically matched to a reconstructed track, divided by the total simulated tracks passing the selections.
Overall standard tracking efficiency at the HLT during Run~3, as a function of the simulated radial position of the track production vertex. In the figure, $t\bar{t}$ simulation for 2025 conditions and an average PU of 62 is used, and the tracks are required to have $\mathrm{p_T}>0.9$ GeV and $|\eta|<2.5$. The tracking efficiency is defined as the ratio of the simulated tracks (with the aforementioned selection requirements) geometrically matched to a reconstructed track, divided by the total simulated tracks passing the selections.
L1T+HLT efficiency of the MET+IsoTrk trigger as a function of the number of tracker layers with valid measurements of the track that pass the offline requirements, in $\tilde{\chi}_{1}^{\pm} \rightarrow \tilde{\chi}_{1}^{0}$+X simulated events for 2022 conditions, where $m_{\tilde{\chi}_{1}^{\pm}}=900$ GeV and $\tilde{\chi}_{1}^{0}$ is nearly mass-degenerate with $\tilde{\chi}_{1}^{\pm}$. The efficiency is shown for LLPs with $c\tau=$ 10, 100, and 1000 cm in black, blue, and red, respectively.
The PHENIX Collaboration at the Relativistic Heavy Ion Collider has measured open heavy-flavor production in minimum bias Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV via the yields of electrons from semileptonic decays of charm and bottom hadrons. Previous heavy-flavor electron measurements indicated substantial modification in the momentum distribution of the parent heavy quarks due to the quark-gluon plasma created in these collisions. For the first time, using the PHENIX silicon vertex detector to measure precision displaced tracking, the relative contributions from charm and bottom hadrons to these electrons as a function of transverse momentum are measured in Au$+$Au collisions. We compare the fraction of electrons from bottom hadrons to previously published results extracted from electron-hadron correlations in $p$$+$$p$ collisions at $\sqrt{s_{_{NN}}}=200$ GeV and find the fractions to be similar within the large uncertainties on both measurements for $p_T>4$ GeV/$c$. We use the bottom electron fractions in Au$+$Au and $p$$+$$p$ along with the previously measured heavy flavor electron $R_{AA}$ to calculate the $R_{AA}$ for electrons from charm and bottom hadron decays separately. We find that electrons from bottom hadron decays are less suppressed than those from charm for the region $3<p_T<4$ GeV/$c$.
Bottom and charm hadron invariant yields as a function of $p_{T}$.
Bottom hadron fraction with respect to heavy flavor electron as a function of $p_{T}$.
Bottom and charm hadron $R_{AA}$ as a function of $p_{T}$.
We present measurements of elliptic flow ($v_2$) of electrons from the decays of heavy-flavor hadrons ($e_{HF}$) by the STAR experiment. For Au+Au collisions at $\sqrt{s_{\rm NN}} = $ 200 GeV we report $v_2$, for transverse momentum ($p_T$) between 0.2 and 7 GeV/c using three methods: the event plane method ($v_{2}${EP}), two-particle correlations ($v_2${2}), and four-particle correlations ($v_2${4}). For Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 62.4 and 39 GeV we report $v_2${2} for $p_T< 2$ GeV/c. $v_2${2} and $v_2${4} are non-zero at low and intermediate $p_T$ at 200 GeV, and $v_2${2} is consistent with zero at low $p_T$ at other energies. The $v_2${2} at the two lower beam energies is systematically lower than at $\sqrt{s_{\rm NN}} = $ 200 GeV for $p_T < 1$ GeV/c. This difference may suggest that charm quarks interact less strongly with the surrounding nuclear matter at those two lower energies compared to $\sqrt{s_{\rm NN}} = 200$ GeV.
Signal-to-background (S/B) ratio as a function of transverse momentum, Au+Au 200 GeV, 0-60% central events with minimum bias trigger
Signal-to-background (S/B) ratio as a function of transverse momentum, Au+Au 200 GeV, 0-60% central events with with High Tower (high pT) trigger
Signal-to-background (S/B) ratio as a function of transverse momentum, Au+Au 39 GeV, 0-60% central events with minimum bias trigger
Flow coefficients v_n for n = 2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at sqrt(s_NN) = 200 GeV, are measured relative to event planes Ψ_n determined at large rapidity. We report v_n as a function of transverse momentum and collision centrality, and study the correlations among the event planes of different order n. The v_n are well described by hydrodynamic models which employ a Glauber Monte Carlo initial state geometry with fluctuations, providing additional constraining power on the interplay between initial conditions and the effects of viscosity as the system evolves. This new constraint improves precision of the extracted viscosity to entropy density ratio eta/s.
Charged hadron azimuthal anisotropy $v_2$, $v_3$, and $v_4$ vs $p_T$ in 0-10% central Au+Au collisions at 200 GeV. The mean $<p_T>$ in each $p_T$ bins used for the $v_n$ measurement is shown in Fig.2.6.
Charged hadron azimuthal anisotropy $v_2$, $v_3$, and $v_4$ vs $p_T$ in 10-20% central Au+Au collisions at 200 GeV. The mean $<p_T>$ in each $p_T$ bins used for the $v_n$ measurement is shown in Fig.2.6.
Charged hadron azimuthal anisotropy $v_2$, $v_3$, and $v_4$ vs $p_T$ in 20-30% central Au+Au collisions at 200 GeV. The mean $<p_T>$ in each $p_T$ bins used for the $v_n$ measurement is shown in Fig.2.6.
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