Using proton-proton collision data collected by the CMS experiment at $\sqrt{s}$ = 13 TeV in 2016$-$2018, corresponding to an integrated luminosity of 140 fb$^{-1}$, the first full reconstruction of the three vector B meson states, B$^{*+}$, B$^{*0}$, and B$^{*0}_\text{s}$, is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be $m(\text{B}^{*+})-m(\text{B}^+)$ = 45.277 $\pm$ 0.039 $\pm$ 0.027 MeV, $m(\text{B}^{*0})- m(\text{B}^0)$ = 45.471 $\pm$ 0.056 $\pm$ 0.028 MeV, and $m(\text{B}^{*0}_\text{s})-m(\text{B}_\text{s})$ = 49.407 $\pm$ 0.132 $\pm$ 0.041 MeV, where the first uncertainties are statistical and the second are systematic. These results improve on the precision of previous measurements by an order of magnitude.
The measured mass differences between vector and ground B meson states.
Extracted masses of $\mathrm{B}^{*+}$, $\mathrm{B}^{*0}$, and $\mathrm{B}^{*0}_{\mathrm{s}}$ mesons. The values are obtained using the measurements in Table 1 and the ground state masses from PDG 2024 (S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)), which are the source of the last uncertainties.
Extracted mass differences between vector B meson states of different flavour. The values are obtained using the measurements in Table 4 and the ground state mass differences from PDG 2024 (S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)), which are the source of the last uncertainties.
The jet cross-section and jet-substructure observables in $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV were measured by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC). Jets are reconstructed from charged-particle tracks and electromagnetic-calorimeter clusters using the anti-$k_{t}$ algorithm with a jet radius $R=0.3$ for jets with transverse momentum within $8.0<p_T<40.0$ GeV/$c$ and pseudorapidity $|η|<0.15$. Measurements include the jet cross section, as well as distributions of SoftDrop-groomed momentum fraction ($z_g$), charged-particle transverse momentum with respect to jet axis ($j_T$), and radial distributions of charged particles within jets ($r$). Also meaureed was the distribution of $ξ=-ln(z)$, where $z$ is the fraction of the jet momentum carried by the charged particle. The measurements are compared to theoretical next-to and next-to-next-to-leading-order calculatios, PYTHIA event generator, and to other existing experimental results. Indicated from these meaurements is a lower particle multiplicity in jets at RHIC energies when compared to models. Also noted are implications for future jet measurements with sPHENIX at RHIC as well as at the future Electron-Ion Collider.
The jet differential cross section as a function of jet $p_T$. Statistical uncertainties are typically smaller than the data points while systematic uncertainties are shown with boxes. An overall normalization systematic of 7% is not included in the point-by-point systematic uncertainties.
Distribution of the SoftDrop groomed momentum fraction $z_g$ for different jet $p_T$ bins. Standard SoftDrop parameters were used ($z_{cut}<0.1$ and $\beta=0$).
$\xi$ distributions for different jet $p_T$ bins.
A study on the Bose-Einstein correlations for triplets of same-sign pions is presented. The analysis is performed using proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 7 TeV, recorded by the LHCb experiment, corresponding to an integrated luminosity of 1.0 fb$^{-1}$. For the first time, the results are interpreted in the core-halo model. The parameters of the model are determined in regions of charged-particle multiplicity. This measurement provides insight into the nature of hadronisation in terms of coherence, showing a coherent emission of pions.
Results of the fit to the three-particle double ratio ($r_{d_{3}}$) for same-sign pion triplets, VELO track multiplicity for pp collision: 5-10.
Results of the fit to the three-particle double ratio ($r_{d_{3}}$) for same-sign pion triplets, VELO track multiplicity for pp collision: 11-20.
Results of the fit to the three-particle double ratio ($r_{d_{3}}$) for same-sign pion triplets, VELO track multiplicity for pp collision: 21-60.
The LHCb collaboration presents a novel suite of heavy-flavour jet substructure measurements at forward rapidity in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 13$ TeV. The jet mass is a perturbatively calculable probe of the virtuality of hard-scattered quarks and gluons, connecting small-distance quantum chromodynamics (QCD) with long-distance experimental measurement. It becomes dominated by nonperturbative corrections at small values, presenting an excellent test of QCD across a broad range of energies. Measuring heavy-flavour jet mass with a theoretically unambiguous flavour definition for the first time probes the gluon splitting mechanism for heavy-flavour production and pushes tests of perturbative QCD to unprecedented theoretical precision. Utilising the soft drop jet-grooming technique to access the perturbative jet core further enhances constraints on first-principles theory. Measurements of the jet mass for jets containing fully reconstructed $B^\pm$ hadrons are reported with and without grooming. These results offer unparalleled tests of quark flavour and mass dependence in QCD and provide a baseline for future studies of heavy-flavour jet quenching in heavy-ion collisions.
Groomed $B^\pm$-tagged jet invariant mass $m_{\textrm{jet,gr}}/p_{\textrm{T,jet}}$ for $R=0.5$ jets reconstructed in pp data, without any WTA flavour requirement. Normalization is set to unity. $10 < p_{\textrm{T,jet}} < 12$ GeV, soft drop $z_{\textrm{cut}}=0.1, \beta=0$.
Groomed $B^\pm$-tagged jet invariant mass $m_{\textrm{jet,gr}}/p_{\textrm{T,jet}}$ for $R=0.5$ jets reconstructed in pp data, without any WTA flavour requirement. Normalization is set to unity. $12 < p_{\textrm{T,jet}} < 15$ GeV, soft drop $z_{\textrm{cut}}=0.1, \beta=0$.
Groomed $B^\pm$-tagged jet invariant mass $m_{\textrm{jet,gr}}/p_{\textrm{T,jet}}$ for $R=0.5$ jets reconstructed in pp data, without any WTA flavour requirement. Normalization is set to unity. $15 < p_{\textrm{T,jet}} < 20$ GeV, soft drop $z_{\textrm{cut}}=0.1, \beta=0$.
The pseudorapidity distribution of charged hadrons produced in Au+Au collisions at a center-of-mass energy of $\sqrt{s_\mathrm{NN}} = 200$ GeV is measured using data collected by the sPHENIX detector. Charged hadron yields are extracted by counting cluster pairs in the inner and outer layers of the Intermediate Silicon Tracker, with corrections applied for detector acceptance, reconstruction efficiency, combinatorial pairs, and contributions from secondary decays. The measured distributions cover $|\eta| < 1.1$ across various centralities, and the average pseudorapidity density of charged hadrons at mid-rapidity is compared to predictions from Monte Carlo heavy-ion event generators. This result, featuring full azimuthal coverage at mid-rapidity, is consistent with previous experimental measurements at the Relativistic Heavy Ion Collider, thereby supporting the broader sPHENIX physics program.
Nch, Npart, and Nch/(Npart/2) values in Table 4, presented in Figure 6.
Nch as a function of $\eta$, presented in Figure 5.
This paper reports measurements of the transverse energy per unit pseudorapidity ($dE_{T}/d\eta$) produced in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV, performed with the sPHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The results cover the pseudorapidity range $\left|\eta\right| < 1.1$ and constitute the first such measurement performed using a hadronic calorimeter at RHIC. Measurements of $dE_{T}/d\eta$ are presented for a range of centrality intervals and the average $dE_{T}/d\eta$ as a function of the number of participating nucleons, $N_{\mathrm{part}}$, is compared to a variety of Monte Carlo heavy-ion event generators. The results are in agreement with previous measurements at RHIC, and feature an improved granularity in $\eta$ and improved precision in low-$N_{\mathrm{part}}$ events.
An example of a reconstructed EMCal di-cluster invariant mass distribution, similar to those used for in situ EMCal tower calibrations. The distributions are made from EMCal cluster pairs using Run 2024 Au+Au data. The prominent peak arises from $\pi^{0}\to\gamma\gamma$ decays.
An example of a reconstructed EMCal di-cluster invariant mass distribution, similar to those used for in situ EMCal tower calibrations. The distributions are made from EMCal cluster pairs using a GEANT-4 simulation of HIJING events. The prominent peak arises from $\pi^{0}\to\gamma\gamma$ decays.
An example of the measured energy distribution in a single OHCal tower, showing the MIP distribution from cosmic-ray data from the detector.
Partonic collectivity is one of the necessary signatures for the formation of Quark-Gluon-Plasma in high-energy nuclear collisions. Number of Constituent Quarks (NCQ) scaling has been observed for light hadron elliptic flow $v_2$ in top energy nuclear collisions at RHIC and the LHC, and this has been theoretically suggested as strong evidence for partonic collectivity. In this letter, a systematic analysis of $v_2$ of $\pi^{\pm}$, $K^{\pm}$, $K^{0}_{S}$, $p$ and $\Lambda$ in Au+Au collisions at ${\sqrt{s_{_{\rm{NN}}}}}$ = 3.2, 3.5, 3.9, and 4.5 GeV, with the STAR experiment at RHIC, is presented. NCQ scaling is markedly violated at 3.2 GeV, consistent with a hadronic-interaction dominated equation of state. However, as the collision energy increases, a gradual evolution to NCQ scaling is observed. This beam-energy dependence of $v_2$ for all hadrons studied provides evidence for the onset of dominant partonic interactions by ${\sqrt{s_{_{\rm{NN}}}}}$ = 4.5 GeV.
$p_{T}$ dependence of $v_{2}$ for $\pi^{+}$ in Au+Au collisions at 3 GeV
$p_{T}$ dependence of $v_{2}$ for $\pi^{+}$ in Au+Au collisions at 3.2 GeV
$p_{T}$ dependence of $v_{2}$ for $\pi^{+}$ in Au+Au collisions at 3.5 GeV
A measurement of the WZ$γ$ triboson production cross section is presented. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ = 13 TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. The analysis focuses on the final state with three charged leptons, $\ell^\pmν\ell^+\ell^-$, where $\ell$ = e or $μ$, accompanied by an additional photon. The observed (expected) significance of the WZ$γ$ signal is 5.4 (3.8) standard deviations. The cross section is measured in a fiducial region, where events with an $\ell$ originating from a tau lepton decay are excluded, to be 5.48 $\pm$ 1.11 fb, which is compatible with the prediction of 3.69 $\pm$ 0.24 fb at next-to-leading order in quantum chromodynamics. Exclusion limits are set on anomalous quartic gauge couplings and on the production cross sections of massive axion-like particles.
The distributions of the variables used in the simultaneous fit for the nonprompt $l$ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
The distributions of the variables used in the simultaneous fit for the nonprompt $\gamma$ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
The distributions of the variables used in the simultaneous fit for the ZZ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
We report measurements of $\varUpsilon(1S)$, $\varUpsilon(2S)$ and $\varUpsilon(3S)$ production in $\textit{p+p}$ collisions at $\sqrt{s}=500\:\mathrm{GeV}$ by the STAR experiment in year 2011, corresponding to an integrated luminosity $\mathcal{L}_{int}=13\:\mathrm{pb^{-1}}$. The results provide precise cross sections, transverse momentum ($p_{T}$) and rapidity ($y$) spectra, as well as cross section ratios for $p_{\mathrm{T}}<10\:\mathrm{GeV/c}$ and $|y|<1$. The dependence of the $\varUpsilon$ yield on charged particle multiplicity has also been measured, offering new insights into the mechanisms of quarkonium production. The data are compared to various theoretical models: the Color Evaporation Model (CEM) accurately describes the $\varUpsilon(1S)$ production, while the Color Glass Condensate + Non-relativistic Quantum Chromodynamics (CGC+NRQCD) model overestimates the data, particularly at low $p_{T}$. Conversely, the Color Singlet Model (CSM) underestimates the rapidity dependence. These discrepancies highlight the need for further development in understanding the production dynamics of heavy quarkonia in high-energy hadronic collisions. The trend in the multiplicity dependence is consistent with CGC/Saturation and String Percolation models or $\varUpsilon$ production happening in multiple parton interactions modeled by PYTHIA8.
The invariant mass distribution of electron pairs collected from p+p collisions at 500 GeV.
Single electron efficiencies.
Upsilon reconstruction efficiencies.
We present the first forward-rapidity measurements of elliptic anisotropy of open-heavy-flavor muons at the BNL Relativistic Heavy Ion Collider. The measurements are based on data samples of Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV collected by the PHENIX experiment in 2014 and 2016 with integrated luminosity of 14.5~nb$^{-1}$. The measurements are performed in the pseudorapidity range $1.2<|\eta|<2$ and cover transverse momenta $1<p_T<4$~GeV/$c$. The elliptic flow of charged hadrons as a function of transverse momentum is also measured in the same kinematic range. We observe significant elliptic flow for both charged hadrons and heavy-flavor muons. The results show clear mass ordering of elliptic flow of light- and heavy-flavor particles. The magnitude of the measured $v_2$ is comparable to that in the midrapidity region. This indicates that there is no strong longitudinal dependence in the quark-gluon-plasma evolution between midrapidity and the rapidity range of this measurement at $\sqrt{s_{_{NN}}}=200$~GeV.
Lastgap $v_2$
Hadron-Muon Ratio at $1.2 < |\eta| < 2.0$
HF Fraction at $1.2 < |\eta| < 2.0$ Top Tuned Slim
Forum