The first evidence for X(3872) production in relativistic heavy ion collisions is reported. The X(3872) production is studied in lead-lead (PbPb) collisions at a center-of-mass energy of $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV per nucleon pair, using the decay chain X(3872) $\to$ J$/\psi\, \pi^+\pi^- \to$ $\mu^+\mu^-\pi^+\pi^-$. The data were recorded with the CMS detector in 2018 and correspond to an integrated luminosity of 1.7 nb$^{-1}$. The measurement is performed in the rapidity and transverse momentum ranges $|y|$ $\lt$ 1.6 and 15 $\lt$ $p_\mathrm{T}$ $\lt$ 50 GeV$/c$. The significance of the inclusive X(3872) signal is 4.2 standard deviations. The prompt X(3872) to $\psi$(2S) yield ratio is found to be $\rho^\mathrm{PbPb} = $ 1.08 $\pm$ 0.49 (stat) $\pm$ 0.52 (syst), to be compared with typical values of 0.1 for pp collisions. This result provides a unique experimental input to theoretical models of the X(3872) production mechanism, and of the nature of this exotic state.
The yield ratio $\rho^{\mathrm{PbPb}}$ of prompt X(3872) over $\psi(\mathrm{2S})$ production in PbPb collisions at 5.02 TeV
The cross section of the diffractive process e^+p -> e^+Xp is measured at a centre-of-mass energy of 318 GeV, where the system X contains at least two jets and the leading final state proton p is detected in the H1 Very Forward Proton Spectrometer. The measurement is performed in photoproduction with photon virtualities Q^2 <2 GeV^2 and in deep-inelastic scattering with 4 GeV^2<Q^2<80 GeV^2. The results are compared to next-to-leading order QCD calculations based on diffractive parton distribution functions as extracted from measurements of inclusive cross sections in diffractive deep-inelastic scattering.
Integrated $e^{+}p$ diffractive dijet cross sections in $\gamma p$. The hadronisation correction factor ($1+\delta_{\text{hadr}}$) applied to the NLO calculation is also listed. The overall normalisation uncertainty of $6\%$ is not included in the table.
Integrated $e^{+}p$ diffractive dijet cross sections in DIS. The hadronisation correction factor ($1+\delta_{\text{hadr}}$) applied to the NLO calculation and the radiative correction ($1+\delta_{\text{rad}}$) are also listed. The overall normalisation uncertainty of $6\%$ is not included in the table.
Ratio of integrated $e^{+}p$ diffractive dijet cross sections for $Q^2<2\,\text{GeV}^2$ (photoproduction) to $Q^2>4\,\text{GeV}^2$ (DIS).
We present a measurement of the cross sections for the associated production of a $W$ boson with at least one heavy quark jet, $b$ or $c$, in proton-antiproton collisions. Data corresponding to an integrated luminosity of 8.7 fb$^{-1}$ recorded with the D0 detector at the Fermilab Tevatron \ppbar Collider at $\sqrt{s}=1.96$ TeV are used to measure the cross sections differentially as a function of the jet transverse momenta in the range 20 to 150 GeV. These results are compared to calculations of perturbative QCD theory as well as predictions from Monte Carlo generators.
The $W + b$-jet production cross sections times $W \to \mu\nu$ branching fraction, ${\rm d}\sigma/{\rm d}p_T^{\rm jet}$.
The $W + c$-jet production cross sections times $W \to \mu\nu$ branching fraction, ${\rm d}\sigma/{\rm d}p_T^{\rm jet}$.
The $\sigma(W+c)/\sigma(W+b)$ cross section ratio in bins of $c(b)$-jet $p_T$.
Inclusive jet, dijet and trijet differential cross sections are measured in neutral current deep-inelastic scattering for exchanged boson virtualities 150 < Q^2 < 15000 GeV^2 using the H1 detector at HERA. The data were taken in the years 2003 to 2007 and correspond to an integrated luminosity of 351 pb^{-1}. Double differential Jet cross sections are obtained using a regularised unfolding procedure. They are presented as a function of Q^2 and the transverse momentum of the jet, P_T^jet, and as a function of Q^2 and the proton's longitudinal momentum fraction, Xi, carried by the parton participating in the hard interaction. In addition normalised double differential jet cross sections are measured as the ratio of the jet cross sections to the inclusive neutral current cross sections in the respective Q^2 bins of the jet measurements. Compared to earlier work, the measurements benefit from an improved reconstruction and calibration of the hadronic final state. The cross sections are compared to perturbative QCD calculations in next-to-leading order and are used to determine the running coupling and the value of the strong coupling constant as alpha_s(M_Z) = 0.1165 (8)_exp (38)_{pdf,theo}.
Double-differential inclusive jet cross sections measured as a function of Q**2 and PT(JET) using the kT jet algorithm. The total systematic uncertainty sums all systematic uncertainties in quadrature, including the uncertainty due to the LAr noise of 0.5% and the total normalisation uncertainty of 2.9%. The correction factors on the theoretical cross sections C(HAD) and C(EW) are listed in the rightmost columns.
Double-differential dijet cross sections measured as a function of Q**2 and MEAN(PT(2JET)) using the kT jet algorithm. The total systematic uncertainty sums all systematic uncertainties in quadrature, including the uncertainty due to the LAr noise of 0.6% and the total normalisation uncertainty of 2.9%. The correction factors on the theoretical cross sections C(HAD) and C(EW) are listed in the rightmost columns.
Double-differential dijet cross sections measured as a function of Q**2 and XI(2) using the kT jet algorithm. The total systematic uncertainty sums all systematic uncertainties in quadrature, including the uncertainty due to the LAr noise of 0.6% and the total normalisation uncertainty of 2.9%. The correction factors on the theoretical cross sections C(HAD) and C(EW) are listed in the rightmost columns.
The first observation of $Z$ boson production in proton-lead collisions at a centre-of-mass energy per proton-nucleon pair of $\sqrt{s_{NN}}=5~\text{TeV}$ is presented. The data sample corresponds to an integrated luminosity of $1.6~\text{nb}^{-1}$ collected with the LHCb detector. The $Z$ candidates are reconstructed from pairs of oppositely charged muons with pseudorapidities between 2.0 and 4.5 and transverse momenta above $20~\text{GeV}/c$. The invariant dimuon mass is restricted to the range $60-120~\text{GeV}/c^2$. The $Z$ production cross-section is measured to be \begin{eqnarray*} \sigma_{Z\to\mu^+\mu^-}(\text{fwd})&=&13.5^{+5.4}_{-4.0}\text{(stat.)}\pm1.2\text{(syst.)}~\text{nb} \end{eqnarray*} in the direction of the proton beam and \begin{eqnarray*} \sigma_{Z\to\mu^+\mu^-}(\text{bwd}) & =&10.7^{+8.4}_{-5.1}\text{(stat.)}\pm1.0\text{(syst.)}~\text{nb} \end{eqnarray*} in the direction of the lead beam, where the first uncertainty is statistical and the second systematic.
The measured Z production cross-sections in proton-lead collisions, measured in the fiducial region defined in the table, in the forward and backward directions. The statistical uncertainty is defined as the 68% confidence interval with symmetric coverage assuming that the number of candidates follows a Poisson distribution.
The forward-backward ratio measured in the overlap region 2.5 < ABS(YRAP) < 4.0. The first uncertainty is statistical, defined as the 68% confidence interval with symmetric coverage. The second uncertainty is systematic and includes the uncertainty on the acceptance correction factor, BETA, for the difference in the detector acceptance of the muons between the forward and backward directions.
Exclusive production of the isoscalar vector mesons $\omega$ and $\phi$ is measured with a 190 GeV$/c$ proton beam impinging on a liquid hydrogen target. Cross section ratios are determined in three intervals of the Feynman variable $x_{F}$ of the fast proton. A significant violation of the OZI rule is found, confirming earlier findings. Its kinematic dependence on $x_{F}$ and on the invariant mass $M_{p\mathrm{V}}$ of the system formed by fast proton $p_\mathrm{fast}$ and vector meson $V$ is discussed in terms of diffractive production of $p_\mathrm{fast}V$ resonances in competition with central production. The measurement of the spin density matrix element $\rho_{00}$ of the vector mesons in different selected reference frames provides another handle to distinguish the contributions of these two major reaction types. Again, dependences of the alignment on $x_{F}$ and on $M_{p\mathrm{V}}$ are found. Most of the observations can be traced back to the existence of several excited baryon states contributing to $\omega$ production which are absent in the case of the $\phi$ meson. Removing the low-mass $M_{p\mathrm{V}}$ resonant region, the OZI rule is found to be violated by a factor of eight, independently of $x_\mathrm{F}$.
Differential cross section ratio R(PHI/OMEGA) and corresponding OZI violation factors F(OZI). R(PHI/OMEGA) is multiplied by 100 to improve readability.
Differential cross section ratio R(PHI/OMEGA) and corresponding OZI violation factors F(OZI) for different cuts on the vector meson momentum P(V). R(PHI/OMEGA) is multiplied by 100 to improve readability.
Spin alignment RHO(00) extracted from the helicity angle distributions for PHI and OMEGA production, in the latter case with various cuts on P(V). The uncertainty is the propagated uncertainty from the linear fits, which in turn includes the quadratic sum of statistical uncertainties and uncertainties from the background subtraction.
We present the first measurements of the differential cross section $d\sigma/dp_{T}^{\gamma}$ for the production of an isolated photon in association with at least two $b$-quark jets. The measurements consider photons with rapidities $|y^\gamma| < 1.0$ and transverse momenta $30 < p_{T}^{\gamma} < 200$~\GeV. The $b$-quark jets are required to have $p_T^{jet}>15$ GeV and $| y^{jet}| < 1.5$. The ratio of differential production cross sections for $\gamma+2~b$-jets to $\gamma+b$-jet as a function of $p_{T}^{\gamma}$ is also presented. The results are based on the proton-antiproton collision data at $\sqrt{s}=$1.96~\TeV collected with the D0 detector at the Fermilab Tevatron Collider. The measured cross sections and their ratios are compared to the next-to-leading order perturbative QCD calculations as well as predictions based on the $k_{T}$-factorization approach and those from the SHERPA and PYTHIA Monte Carlo event generators.
The differential GAMMA+2BJET production cross section, DSIG/DPT(GAMMA), in bins of PT(GAMMA).
The differential GAMMA+BJET production cross section, DSIG/DPT(GAMMA), in bins of PT(GAMMA).
The SIG(GAMMA 2BJET)/SIG(GAMMA BJET) cross section ratio in bins of PT(GAMMA).
Measurements of normalised cross sections for the production of photons and neutrons at very small angles with respect to the proton beam direction in deep-inelastic $ep$ scattering at HERA are presented as a function of the Feynman variable $x_F$ and of the centre-of-mass energy of the virtual photon-proton system $W$. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of $131 \mathrm{pb}^{-1}$. The measurement is restricted to photons and neutrons in the pseudorapidity range $\eta>7.9$ and covers the range of negative four momentum transfer squared at the positron vertex $6<Q^2<100$ GeV$^2$, of inelasticity $0.05<y<0.6$ and of $70<W<245 $GeV. To test the Feynman scaling hypothesis the $W$ dependence of the $x_F$ dependent cross sections is investigated. Predictions of deep-inelastic scattering models and of models for hadronic interactions of high energy cosmic rays are compared to the measured cross sections.
The fraction of DIS events with forward photons. For each measurement, the statistical, the uncorrelated systematic uncertainties and the bin-to-bin correlated systematic uncertainties due to the FNC absolute energy scale (EFNC), the measurement of the particle impact position in the FNC (XYFNC) and the model dependence of the data correction (model) are given.
The fraction of DIS events with forward neutrons. For each measurement, the statistical, the uncorrelated systematic uncertainties and the bin-to-bin correlated systematic uncertainties due to the FNC absolute energy scale (EFNC), the measurement of the particle impact position in the FNC (XYFNC) and the model dependence of the data correction (model) are given.
Normalised cross sections of forward photon production in DIS as a function of XF. For each measurement, the statistical, the uncorrelated systematic uncertainties and the bin-to-bin correlated systematic uncertainties due to the FNC absolute energy scale (EFNC), the measurement of the particle impact position in the FNC (XYFNC) and the model dependence of the data correction (model) are given.
We study the processes $e^+ e^-\to K_S^0 K_L^0 \gamma$, $K_S^0 K_L^0 \pi^+\pi^-\gamma$, $K_S^0 K_S^0 \pi^+\pi^-\gamma$, and $K_S^0 K_S^0 K^+K^-\gamma$, where the photon is radiated from the initial state, providing cross section measurements for the hadronic states over a continuum of center-of-mass energies. The results are based on 469 fb$^{-1}$ of data collected with the BaBar detector at SLAC. We observe the $\phi(1020)$ resonance in the $K_S^0 K_L^0$ final state and measure the product of its electronic width and branching fraction with about 3% uncertainty. We present a measurement of the $e^+ e^-\to K_S^0 K_L^0 $ cross section in the energy range from 1.06 to 2.2 GeV and observe the production of a resonance at 1.67 GeV. We present the first measurements of the $e^+ e^-\to K_S^0 K_L^0 \pi^+\pi^-$, $K_S^0 K_S^0 \pi^+\pi^-$, and $K_S^0 K_S^0 K^+K^-$ cross sections, and study the intermediate resonance structures. We obtain the first observations of \jpsi decay to the $K_S^0 K_L^0 \pi^+\pi^-$, $K_S^0 K_S^0 \pi^+\pi^-$, and $K_S^0 K_S^0 K^+K^-$ final states.
Cross section measurement for PHI(1020).
Mass measurement for PHI(1020).
Measurement of the PHI(1020) width.
We present measurements of the inclusive production of antideuterons in $e^+e^-$ annihilation into hadrons at $\approx 10.58 \mathrm{\,Ge\kern -0.1em V}$ center-of-mass energy and in $\Upsilon(1S,2S,3S)$ decays. The results are obtained using data collected by the BABAR detector at the PEP-II electron-positron collider. Assuming a fireball spectral shape for the emitted antideuteron momentum, we find $\mathcal{B}(\Upsilon(1S) \to \bar{d}X) = (2.81 \pm 0.49 \mathrm{(stat)} {}^{+0.20}_{-0.24} \mathrm{(syst)})/! \times /! 10^{-5}$, $\mathcal{B}(\Upsilon(2S) \to \bar{d}X) = (2.64 \pm 0.11 \mathrm{(stat)} {}^{+0.26}_{-0.21} \mathrm{(syst)})/! \times /! 10^{-5}$, $\mathcal{B}(\Upsilon(3S) \to \bar{d}X) = (2.33 \pm 0.15 \mathrm{(stat)} {}^{+0.31}_{-0.28} \mathrm{(syst)})/! \times /! 10^{-5}$, and $\sigma (e^+e^- \to \bar{d}X) = (9.63 \pm 0.41 \mathrm{(stat)} {}^{+1.17}_{-1.01} \mathrm{(syst)}) \mbox{\,fb}$.
The rate of antideuteron production from the decay of UPSILON(3S).
The rate of antideuteron production from the decay of UPSILON(2S).
The rate of antideuteron production from the decay of UPSILON(1S).
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