Production fraction ratios of B$^+$, B$^0$, and B$^0_\mathrm{s}$ mesons are measured in proton-proton collisions at $\sqrt{s}$ = 13 TeV using a special data set recorded in 2018 with high-rate triggers designed to collect an unbiased sample of $10^{10}$ b hadrons with the CMS experiment at the LHC. These data allow the use of the open-charm decays of B mesons (B$_\mathrm{(s)}$$\to$$π$D$_\mathrm{(s)}$) where the D meson decays into fully hadronic final states. Production fraction ratios as functions of B meson transverse momentum ($p_\mathrm{T}$) and rapidity ($y$) are measured using the open-charm decays in the kinematic range of 8 $\lt$$p_\mathrm{T}$$\lt$ 60 GeV and $\lvert y \rvert$$\lt$ 2.25. In addition, the same data are used to measure the relative production fraction ratios with the charmonium decay channels (B$_\mathrm{(s)}$$\to$ X$\,$J/$ψ$ with X indicating a K$^+$, K$^*$(892)$^0$, or $ϕ$(1020) meson) with the J/$ψ$ meson decaying into a pair of muons. By utilizing known branching fractions, precision theoretical calculations, and the open-charm results, the production fraction ratios in the charmonium samples are determined with an absolute normalization for the first time. These results also improve several world-average values of the ratios of branching fractions of B meson decays to charmonium and open-charm states. Finally, we test isospin invariance in B meson production in proton-proton collisions and observe that it holds within the experimental precision.
The invariant mass distribution of $B^+$ candidates, corrected using the $D^0$ meson mass, is shown for $13 < p_{T} < 18$ GeV along with the corresponding fit.
The invariant mass distribution of $B^0$ candidates, corrected using the $D^-$ meson mass, is shown for $18 < p_{T} < 23$ GeV along with the corresponding fit.
The invariant mass distribution of $B_s^{0}$ candidates, corrected using the $D^-_{s}$ meson mass, is shown for $23 < p_{T} < 28$ GeV along with the corresponding fit.
The observation of associated production of an $Υ$(1S) meson with a Z boson and a measurement of the ratio of its fiducial cross section to the fiducial cross section of the Z boson are presented. Both the $Υ$(1S) meson and the Z boson are identified via decays into a pair of opposite-sign muons. The analysis is based on proton-proton (pp) collision data at $\sqrt{s}$ = 13 TeV, collected with the CMS detector in 2016$-$2018 and corresponding to an integrated luminosity of 138 fb$^{-1}$. Using the production of the Z boson decaying into four muons as a normalization channel, the ratio of the fiducial cross sections $σ$(pp $\to$ Z $+$$Υ$(1S))$\mathcal{B}$(Z $\to$$μ^+μ^-$)$\mathcal{B}$($Υ$(1S) $\to$$μ^+μ^-$ ) to $σ$(pp $\to$ Z)$\mathcal{B}$(Z $\to$ 4$μ$) is measured to be $\mathcal{R}_{\mathrm{Z+Υ}\mathrm{(1S)}}$ = (21.1 $\pm$ 55 (stat) $\pm$ 0.6 (syst) $\times$ 10$^{-3}$), where stat and syst denote the statistical and systematic uncertainties, respectively. The result is used to extract the effective double-parton scattering cross section $σ_\text{eff}$ = 13.0$^{+7.7}_{-3.4}$. In addition, for the first time, $σ_\text{eff}$ is measured in bins of the transverse momentum of the $Υ$(1S) meson or of the Z boson.
$\sigma(\mathrm{pp}\to\mathrm{Z+Y(1S)})\mathcal{B}(\mathrm{Z}\to\mu\mu)\mathcal{B}(\mathrm{Y(1S)}\to\mu\mu) / \sigma(\mathrm{pp}\to\mathrm{Z})\mathcal{B}(\mathrm{Z}\to\mu\mu\mu\mu)$
DPS $\sigma(\mathrm{pp}\to\mathrm{Z+Y(1S)})\mathcal{B}(\mathrm{Z}\to\mu\mu)\mathcal{B}(\mathrm{Y(1S)}\to\mu\mu) / \sigma(\mathrm{pp}\to\mathrm{Z})\mathcal{B}(\mathrm{Z}\to\mu\mu\mu\mu)$
$\sigma(\mathrm{pp}\to\mathrm{Z+Y(1S)})\mathcal{B}(\mathrm{Z}\to\mu\mu)\mathcal{B}(\mathrm{Y(1S)}\to\mu\mu) / \sigma(\mathrm{pp}\to\mathrm{Z})\mathcal{B}(\mathrm{Z}\to\mu\mu\mu\mu)$
The fundamental building blocks of the proton, quarks and gluons, have been known for decades. However, we still have an incomplete theoretical and experimental understanding of how these particles and their dynamics give rise to the quantum bound state of the proton and its physical properties, such as for example its spin. The two up and the single down quarks that comprise the proton in the simplest picture account only for a few percent of the proton mass, the bulk of which is in the form of quark kinetic and potential energy and gluon energy from the strong force. An essential feature of this force, as described by quantum chromodynamics, is its ability to create matter-antimatter quark pairs inside the proton that exist only for a very short time. Their fleeting existence makes the antimatter quarks within protons difficult to study, but their existence is discernible in reactions where a matter-antimatter quark pair annihilates. In this picture of quark-antiquark creation by the strong force, the probability distributions as a function of momentum for the presence of up and down antimatter quarks should be nearly identical, since their masses are quite similar and small compared to the mass of the proton. In the present manuscript, we show evidence from muon pair production measurements that these distributions are significantly different, with more abundant down antimatter quarks than up antimatter quarks over a wide range of momentum. These results revive interest in several proposed mechanisms as the origin of this antimatter asymmetry in the proton that had been disfavored by the previous results and point to the future measurements that can distinguish between these mechanisms.
Cross section ratios $\sigma_{D}/2\sigma_{H}$ binned in $x_t$ with their statistical and systematic uncertainties and the average values for the kinematic variables of each $x_t$ bin. The cross section ratios are defined as the ratio of luminosity-corrected yields from the hydrogen and deuterium targets. The final column is the experimental resolution in $x_t$ as determined by Monte Carlo simulations.
Ratios of $\bar{d}(x)$ to $\bar{u}(x)$ with their upper and lower statistical and systematic uncertainties. The analysis was based on the present cross section ratio data, and next-to-leading order calculations of the Drell-Yan cross sections using CT18 parton distributions for all except the ratio of $\bar{d}(x)$ to $\bar{u}(x)$. The systematic uncertainty is fully correlated among all $x$ bins. The systematic uncertainty does not include a contribution from the choice of the base (CT18) pdf, which is small if added in quadrature to the other systematic uncertainties.
Ratios of $\mathbf{\sigma_D}$ to $\mathbf{2\sigma_H}$ as a function of $\mathbf{P_T}$. Ratios of $\sigma_D$ to $2\sigma_H$ with their statistical and systematic uncertainties as a function of transverse momentum, $P_T$. The cross section ratios are defined as the ratio of luminosity-corrected yields from the hydrogen and deuterium targets. The final column, $\delta P_T$ is the experimental resolution in $P_T$ as determined by Monte Carlo simulation.
We report the $p+p$ and $p+d$ differential cross sections measured in the SeaQuest experiment for $J/\psi$ and $\psi\left(2S\right)$ production at 120 GeV beam energy covering the forward $x$-Feynman ($x_F$) range of $0.5 < x_F <0.9$. The measured cross sections are in good agreement with theoretical calculations based on the nonrelativistic QCD (NRQCD) using the long-distance matrix elements deduced from a recent global analysis of proton- and pion-induced charmonium production data. The $\sigma_{\psi\left(2S\right)} / \sigma_{J/\psi}$ cross section ratios are found to increase as $x_F$ increases, indicating that the $q \bar{q}$ annihilation process has larger contributions in the $\psi\left(2S\right)$ production than the $J/\psi$ production. The $\sigma_{pd}/2\sigma_{pp}$ cross section ratios are observed to be significantly different for the Drell-Yan process and $J/\psi$ production, reflecting their different production mechanisms. We find that the $\sigma_{pd}/2\sigma_{pp}$ ratios for $J/\psi$ production at the forward $x_F$ region are sensitive to the $\bar{d}/ \bar{u}$ flavor asymmetry of the proton sea, analogous to the Drell-Yan process. The transverse momentum ($p_T$) distributions for $J/\psi$ and $\psi\left(2S\right)$ production are also presented and compared with data collected at higher center-of-mass energies.
The differential cross sections per nucleon, $d\sigma/dx_{F}$ (in nb), for $J/\psi$ production in $p+p$ collision at 120 GeV for different $x_F$ bins.
The differential cross sections per nucleon, $d\sigma/dx_{F}$ (in nb), for $J/\psi$ production in $p+d$ collision at 120 GeV for different $x_F$ bins.
The differential cross sections per nucleon, $d\sigma/dx_{F}$ (in nb), for $\psi(2S)$ production in $p+p$ collision at 120 GeV for different $x_F$ bins.
We present the first measurements of the forward and midrapidity $η$-meson cross sections from $p$$+$$p$ collisions at $\sqrt{s}=500$ and $510$~GeV, respectively. We also report the midrapidity $η/π^0$ ratio at 510 GeV. The forward cross section is measured differentially in $η$-meson transverse momentum ($p_T$) from 1.0 to 6.5~GeV/$c$ for pseudorapidity $3.0<|η|<3.8$. The midrapidity cross section is measured from 3.5 to 44 GeV/$c$ for pseudorapidity $|η|<0.35$. Both cross sections serve as critical inputs to an updated global analysis of the $η$-meson fragmentation functions.
The invariant differential cross section of $\eta$ mesons at forward rapidity in pp collisions at center-of-mass energy 500 GeV.
The invariant differential cross section of $\eta$ mesons at central rapidity in pp collisions at center-of-mass energy 510 GeV.
The ratio of $\eta$ to $\pi^0$ cross sections at central rapidity in pp collisions at center-of-mass energy 510 GeV.
We present the measurement of the $p_{\rm T}$-differential production cross section of $ω$ mesons in pp and p$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV at midrapidity by ALICE. In addition, the first measurement of the nuclear modification factor $R_{\text{pPb}}$ for $ω$ mesons at LHC energies is presented, complementing the existing measurements of lighter neutral mesons such as the $π^0$ and $η$. Within the measured $p_{\rm T}$-range, the $R_{\text{pPb}}$ of $ω$ mesons is compatible with no cold nuclear matter effects within the uncertainties, consistent with previous measurements at lower energies. The $ω/π^0$ ratio is presented for both collision systems, showing no collision system dependence within the uncertainties. The comparison to previously published $ω/π^0$ ratios at lower and higher collision energies in pp collisions suggests a decreasing trend of the ratio above $p_{\rm T}=~4 $ GeV/$c$ with increasing collision energy. The data in both collision systems are compared to predictions from PYTHIA, EPOS LHC and DPMJET event generators, revealing significant shortcomings in these models' ability to describe the production of $ω$ mesons.
Differential production cross section of $\omega$ mesons in pp collisions at 5.02 TeV. In addition to the edges of the $p_{\rm T}$ intervals, the table shows the corresponding $p_{\rm T}$ position as described in the publication.
Differential production cross section of $\omega$ mesons in p--Pb collisions at 5.02 TeV. In addition to the edges of the $p_{\rm T}$ intervals, the table shows the corresponding $p_{\rm T}$ position as described in the publication.
Production ratio of $\omega$ to $\pi^{0}$ mesons in pp collisions at 5.02 TeV.
The $p_{\rm T}$-differential cross section of $\omega$ meson production in pp collisions at $\sqrt{s}= 13$ TeV at midrapidity ($|y|<0.5$) was measured with the ALICE detector at the LHC, covering an unprecedented transverse-momentum range of $1.6 <p_{\rm T}< 50$ GeV/$c$. The meson is reconstructed via the $\omega\rightarrow\pi^+\pi^-\pi^0$ decay channel. The results are compared with various theoretical calculations: PYTHIA8.2 with the Monash 2013 tune overestimates the data by up to 50%, whereas good agreement is observed with Next-to-Leading Order (NLO) calculations incorporating $\omega$ fragmentation using a broken SU(3) model. The $\omega/\pi^0$ ratio is presented and compared with theoretical calculations and the available measurements at lower collision energies. The presented data triples the $p_{\rm T}$ ranges of previously available measurements. A constant ratio of $C^{\omega/\pi^0}=0.578\pm0.006~\text{(stat.)}\pm 0.013~\text{(syst.)}$ is found above a transverse momentum of $4$ GeV/$c$, which is in agreement with previous findings at lower collision energies within the systematic and statistical uncertainties.
Invariant differential cross section of OMEGA mesons produced in inelastic pp collisions at center-of-mass energy 13 TeV, the uncertainty of sigma_{MB} of 1.58% is not included in the systematic error.
The measured ratio of cross sections for inclusive OMEGA to PI0 production at a centre-of-mass energy of 13 TeV.
Measurements are presented of the W and Z boson production cross sections in proton-proton collisions at a center-of-mass energy of 13.6 TeV. Data collected in 2022 and corresponding to an integrated luminosity of 5.01 fb$^{-1}$ with one or two identified muons in the final state are analyzed. The results for the products of total inclusive cross sections and branching fractions for muonic decays of W and Z bosons are 11.93 $\pm$ 0.08 (syst) $\pm$ 0.17 (lumi) $^{+0.07}_{-0.07}$ (acceptance) nb for W$^+$ boson production, 8.86 $\pm$ 0.06 (syst) $\pm$ 0.12 (lumi) $^{+0.05}_{-0.06}$ (acceptance) nb for W$^-$ boson production, and 2.021 $\pm$ 0.009 (syst) $\pm$ 0.028 (lumi) $^{+0.011}_{-0.013}$ (acceptance) nb for the Z boson production in the dimuon mass range of 60$-$120 GeV, all with negligible statistical uncertainties. Furthermore, the corresponding fiducial cross sections, as well as cross section ratios for both fiducial and total phase space, are provided. The ratios include charge-separated results for W boson production (W$^+$ and W$^-$) and the sum of the two contributions (W$^\pm$), each relative to the measured Z boson production cross section. Additionally, the ratio of the measured cross sections for W$^+$ and W$^-$ boson production is reported. All measurements are in agreement with theoretical predictions, calculated at next-to-next-to-leading order accuracy in quantum chromodynamics.
Corrected normalized distribution of the transverse momentum of the leading muon in the Z boson signal region. Simulated contributions from Z boson, electroweak, and ttbar production, as well as their sum, and the data are shown.
Corrected normalized distribution of the transverse momentum of the trailing muon in the Z boson signal region. Simulated contributions from Z boson, electroweak, and ttbar production, as well as their sum, and the data are shown.
Corrected normalized distribution of the missing transverse momentum in the Z boson signal region. Simulated contributions from Z boson, electroweak, and ttbar production, as well as their sum, and the data are shown.
Bound states of charm and anticharm quarks, known as charmonia, have a rich spectroscopic structure that can be used to probe the dynamics of hadron production in high-energy hadron collisions. Here, the cross section ratio of excited ($ψ$(2S)) and ground state (J/$ψ$) vector mesons is measured as a function of the charged-particle multiplicity in proton-lead (pPb) collisions at a center-of-mass (CM) energy per nucleon pair of 8.16 TeV. The data corresponding to an integrated luminosity of 175 nb$^{-1}$ were collected using the CMS detector. The ratio is measured separately for prompt and nonprompt charmonia in the transverse momentum range 6.5 $\lt$$p_\text{T}$$\lt$ 30 GeV and in four rapidity ranges spanning $-$2.865 $\lt$$y_\text{CM}$$\lt$ 1.935. For the first time, a statistically significant multiplicity dependence of the prompt cross section ratio is observed in proton-nucleus collisions. There is no clear rapidity dependence in the ratio. The prompt measurements are compared with a theoretical model which includes interactions with nearby particles during the evolution of the system. These results provide additional constraints on hadronization models of heavy quarks in nuclear collisions.
Normalized $\sigma_{\psi(2S)}/\sigma_{J/\psi}$ in $6.5<p_T<30.0\,GeV$ and $ -2.865 < y_{CM} < -2$ as functions of normalized $\text{N}^{{\text{corr.}}}_{\text{track}}$
Normalized $\sigma_{\psi(2S)}/\sigma_{J/\psi}$ in $6.5<p_T<30.0\,GeV$ and $ -2 < y_{CM} < -1$ as functions of normalized $\text{N}^{{\text{corr.}}}_{\text{track}}$
Normalized $\sigma_{\psi(2S)}/\sigma_{J/\psi}$ in $6.5<p_T<30.0\,GeV$ and $ -1 < y_{CM} < 1$ as functions of normalized $\text{N}^{{\text{corr.}}}_{\text{track}}$
The transverse momentum ($p_{\rm T}$) differential production cross section of the promptly produced charm-strange baryon $\Xi_{\rm c}^{0}$ (and its charge conjugate $\overline{\Xi_{\rm c}^{0}}$) is measured at midrapidity via its hadronic decay into ${\rm \pi^{+}}\Xi^{-}$ in p$-$Pb collisions at a centre-of-mass energy per nucleon$-$nucleon collision $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV with the ALICE detector at the LHC. The $\Xi_{\rm c}^{0}$ nuclear modification factor ($R_{\rm pPb}$), calculated from the cross sections in pp and p$-$Pb collisions, is presented and compared with the $R_{\rm pPb}$ of $\Lambda_{\rm c}^{+}$ baryons. The ratios between the $p_{\rm T}$-differential production cross section of $\Xi_{\rm c}^{0}$ baryons and those of $\mathrm {D^0}$ mesons and $\Lambda_{\rm c}^{+}$ baryons are also reported and compared with results at forward and backward rapidity from the LHCb Collaboration. The measurements of the production cross section of prompt $\Xi^0_{\rm c}$ baryons are compared with a model based on perturbative QCD calculations of charm-quark production cross sections, which includes only cold nuclear matter effects in p$-$Pb collisions, and underestimates the measurement by a factor of about 50. This discrepancy is reduced when the data is compared with a model that includes string formation beyond leading-colour approximation or in which hadronisation is implemented via quark coalescence. The $p_{\rm T}$-integrated cross section of prompt $\Xi^0_{\rm c}$-baryon production at midrapidity extrapolated down to $p_{\rm T}$ = 0 is also reported. These measurements offer insights and constraints for theoretical calculations of the hadronisation process. Additionally, they provide inputs for the calculation of the charm production cross section in p$-$Pb collisions at midrapidity.
Prompt $\Xi_\mathrm{c}^0$ productions cross-section as a function of $p_\mathrm{T}$ in p–Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV.
$\Xi_\mathrm{c}^0~R_\mathrm{pPb}$ as a function of $p_\mathrm{T}$ in p–Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV.
$\Xi_\mathrm{c}^0/\mathrm{D}^0$ ratio as a function of $p_\mathrm{T}$ in p–Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV.
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