The $pp \to W^{\pm} (\to μ^{\pm} ν_μ) X$ cross-sections are measured at a proton-proton centre-of-mass energy $\sqrt{s} = 5.02$ TeV using a dataset corresponding to an integrated luminosity of 100 pb$^{-1}$ recorded by the LHCb experiment. Considering muons in the pseudorapidity range $2.2 < η< 4.4$, the cross-sections are measured differentially in twelve intervals of muon transverse momentum between $28 < p_\mathrm{T} < 52$ GeV. Integrated over $p_\mathrm{T}$, the measured cross-sections are \begin{align*} σ_{W^+ \to μ^+ ν_μ} &= 300.9 \pm 2.4 \pm 3.8 \pm 6.0~\text{pb}, \\ σ_{W^- \to μ^- \barν_μ} &= 236.9 \pm 2.1 \pm 2.7 \pm 4.7~\text{pb}, \end{align*} where the first uncertainties are statistical, the second are systematic, and the third are associated with the luminosity calibration. These integrated results are consistent with theoretical predictions. This analysis introduces a new method to determine the $W$-boson mass using the measured differential cross-sections corrected for detector effects. The measurement is performed on this statistically limited dataset as a proof of principle and yields \begin{align*} m_W = 80369 \pm 130 \pm 33~\text{MeV}, \end{align*} where the first uncertainty is experimental and the second is theoretical.
The measured differential cross sections ($d\sigma/dp_T$) for $W^+$. The first systematic uncertainty is statistical and the second is systematic.
The measured differential cross sections ($d\sigma/dp_T$) for $W^-$. The first systematic uncertainty is statistical and the second is systematic.
The correlation matrix corresponding to the statistical uncertainties on the differential cross-section ($d\sigma/dp_T$) fit results for $W^+$. To combine with $W^-$, use the rows and columns ordered as $W^+$ and then $W^-$. Assume no correlation in the statistical uncertainties between $W^+$ and $W^-$ (zero entries in the off-diagonal blocks).
The PHENIX experiment at the Relativistic Heavy Ion Collider has measured low-mass vector-meson ($ω+ρ$ and $ϕ$) production through the dimuon decay channel at forward rapidity $(1.2<|\mbox{y}|<2.2)$ in $p$$+$$p$ and Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$~GeV. The low-mass vector-meson yield and nuclear-modification factor were measured as a function of the average number of participating nucleons, $\langle N_{\rm part}\rangle$, and the transverse momentum $p_T$. These results were compared with those obtained via the kaon decay channel in a similar $p_T$ range at midrapidity. The nuclear-modification factors in both rapidity regions are consistent within the uncertainties. A comparison of the $ω+ρ$ and $J/ψ$ mesons reveals that the light and heavy flavors are consistently suppressed across both $p_T$ and ${\langle}N_{\rm part}\rangle$. In contrast, the $ϕ$ meson displays a nuclear-modification factor consistent with unity, suggesting strangeness enhancement in the medium formed.
The differential cross sections of $\omega+\rho$ mesons as a function of $p_T$ in $p+p$ collisions. The systematic uncertainties of type-A (uncorrelated) are combined with statistical uncertainties in quadrature and are labeled as stat. Type-B (correlated) systematic uncertainties are listed as sys.
The differential cross sections of $\phi$ meson as a function of $p_T$ in $p+p$ collisions. The systematic uncertainties of type-A (uncorrelated) are combined with statistical uncertainties in quadrature and are labeled as stat. Type-B (correlated) systematic uncertainties are listed as sys.
The invariant yields of $\phi$ and $\omega+\rho$ mesons as a function of $p_T$ in Au+Au collisions. The systematic uncertainties of type-A (uncorrelated) are combined with statistical uncertainties in quadrature and are labeled as stat. Type-B (correlated) systematic uncertainties are listed as sys.
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 $z_{\textrm{cut}}=0.1, \beta=0$.
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
We report the first measurement of the azimuthal anisotropy of J$/\psi$ at forward rapidity ($1.2<|\eta|<2.2$) in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV at the Relativistic Heavy Ion Collider. The data were collected by the PHENIX experiment in 2014 and 2016 with integrated luminosity of 14.5~nb$^{-1}$. The second Fourier coefficient ($v_2$) of the azimuthal distribution of $J/\psi$ is determined as a function of the transverse momentum ($p_T$) using the event-plane method. The measurements were performed for several selections of collision centrality: 0%--50%, 10%--60%, and 10%-40%. We find that in all cases the values of $v_2(p_T)$, which quantify the elliptic flow of J$/\psi$, are consistent with zero. The results are consistent with measurements at midrapidity, indicating no significant elliptic flow of the J$/\psi$ within the quark-gluon-plasma medium at collision energies of $\sqrt{s_{_{NN}}}=200$ GeV.
JPSI v2 in Au+Au collisions as a function of pT (GeV/c) for 10%--60% centrality with pT binned by [0, 1], [1, 2], [2, 3], and [3, 5] GeV/c.
JPSI v2 in Au+Au collisions as a function of pT (GeV/c) for 10%--60% centrality with pT binned by [0, 0.5], [0.5, 1], [1, 5], and [0, 5] GeV/c.
JPSI v2 in Au+Au collisions as a function of pT (GeV/c) for 10%--40% centrality with pT binned by [0, 2], [2, 5], and [5, 10] GeV/c.
The $J/\psi$ and $\psi(2S)$ charmonium states, composed of $c\bar{c}$ quark pairs and known since the 1970s, are widely believed to serve as ideal probes to test quantum chromodynamics in high-energy hadronic interactions. However, there is not yet a complete understanding of the charmonium-production mechanism. Recent measurements of $J/\psi$ production as a function of event charged-particle multiplicity at the collision energies of both the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) show enhanced $J/\psi$ production yields with increasing multiplicity. One potential explanation for this type of dependence is multiparton interactions (MPI). We carry out the first measurements of self-normalized $J/\psi$ yields and the $\psi(2S)$ to $J/\psi$ ratio at both forward and backward rapidities as a function of self-normalized charged-particle multiplicity in $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV. In addition, detailed {\sc pythia} studies tuned to RHIC energies were performed to investigate the MPI impacts. We find that the PHENIX data at RHIC are consistent with recent LHC measurements and can only be described by {\sc pythia} calculations that include MPI effects. The forward and backward $\psi(2S)$ to $J/\psi$ ratio, which serves as a unique and powerful approach to study final-state effects on charmonium production, is found to be less dependent on the charged-particle multiplicity.
Self-normalized $J/\psi$ yields as a function of self-normalized $N_{ch}$ for the same arm before subtraction
Self-normalized $J/\psi$ yields as a function of self-normalized $N_{ch}$ for the same arm after subtraction
Self-normalized $J/\psi$ yields as a function of self-normalized $N_{ch}$ for opposite arms
The first study of $J/ψϕ$ production in diffractive processes in proton-proton collisions is presented. The study is based on an LHCb dataset recorded at centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5 fb$^{-1}$. The data disfavour a nonresonant $J/ψϕ$ production but are consistent with a resonant model including several resonant states observed previously only in $B^+ \to J/ψϕK^+$ decays. The $χ_{c0}(4500)$ state is observed with a significance over $6σ$ and the $χ_{c1}(4274)$ is confirmed with a significance of more than $4σ$.
Total $J/\psi(\to \mu^+ \mu^-)\phi(\to K^+ K^-)$ diffractive production cross-section, multiplied by $\mathcal{B}(J/\psi \to \mu^+ \mu^-)$ and $\mathcal{B}(\phi \to K^+ K^-)$ branching ratios.
$\chi_{c1}(4140) \to J/\psi(\to \mu^+ \mu^-)\phi(\to K^+ K^-)$ diffractive production cross-section, multiplied by $\mathcal{B}(J/\psi \to \mu^+ \mu^-)$ and $\mathcal{B}(\phi \to K^+ K^-)$ branching ratios.
$\chi_{c1}(4274) \to J/\psi(\to \mu^+ \mu^-)\phi(\to K^+ K^-)$ diffractive production cross-section, multiplied by $\mathcal{B}(J/\psi \to \mu^+ \mu^-)$ and $\mathcal{B}(\phi \to K^+ K^-)$ branching ratios.
The PHENIX experiment measured the centrality dependence of two-pion Bose-Einstein correlation functions in $\sqrt{s_{_{NN}}}=200$~GeV Au$+$Au collisions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. The data are well represented by Lévy-stable source distributions. The extracted source parameters are the correlation-strength parameter $\lambda$, the Lévy index of stability $\alpha$, and the Lévy-scale parameter $R$ as a function of transverse mass $m_T$ and centrality. The $\lambda(m_T)$ parameter is constant at larger values of $m_T$, but decreases as $m_T$ decreases. The Lévy scale parameter $R(m_T)$ decreases with $m_T$ and exhibits proportionality to the length scale of the nuclear overlap region. The Lévy exponent $\alpha(m_T)$ is independent of $m_T$ within uncertainties in each investigated centrality bin, but shows a clear centrality dependence. At all centralities, the Lévy exponent $\alpha$ is significantly different from that of Gaussian ($\alpha=2$) or Cauchy ($\alpha=1$) source distributions. Comparisons to the predictions of Monte-Carlo simulations of resonance-decay chains show that in all but the most peripheral centrality class (50%-60%), the obtained results are inconsistent with the measurements, unless a significant reduction of the in-medium mass of the $\eta'$ meson is included. In each centrality class, the best value of the in-medium $\eta'$ mass is compared to the mass of the $\eta$ meson, as well as to several theoretical predictions that consider restoration of $U_A(1)$ symmetry in hot hadronic matter.
The transverse-mass dependence of the correlation-strength parameter $\lambda$ in 0-10% centrality bin obtained from Lévy fits with Eq. (9).
The transverse-mass dependence of the correlation-strength parameter $\lambda$ in 10-20% centrality bin obtained from Lévy fits with Eq. (9).
The transverse-mass dependence of the correlation-strength parameter $\lambda$ in 20-30% centrality bin obtained from Lévy fits with Eq. (9).
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