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.
Using a data sample collected with the BESIII detector operating at the BEPCII storage ring, we observe a new neutral state $Z_c(3900)^{0}$ with a significance of $10.4\sigma$. The mass and width are measured to be $3894.8\pm2.3\pm3.2$ MeV/$c^2$ and $29.6\pm8.2\pm8.2$~MeV, respectively, where the first error is statistical and the second systematic. The Born cross section for $e^+e^-\to\pi^0\pi^0 J/\psi$ and the fraction of it attributable to $\pi^0 Z_c(3900)^{0}\to\pi^0\pi^0 J/\psi$ in the range $E_{cm}=4.19-4.42$ GeV are also determined. We interpret this state as the neutral partner of the four-quark candidate $Z_c(3900)^\pm$.
Efficiencies, yields, $R=\frac{\sigma(e^+e^-\to\pi^0 Z_c(3900)^{0}\to\pi^0\pi^0 J/\psi)}{\sigma(e^+e^-\to\pi^0\pi^0 J/\psi)}$, and $\pi^0\pi^0 J/\psi$ Born cross sections at each energy point. For $N(Z_c^0)$ and $N(\pi^0\pi^0 J/\psi)$ errors and upper limits are statistical only. For $R$ and $\sigma_{\rm Born}$, the first errors and statistical and second errors are systematic. The statistical uncertainties on the efficiencies are negligible. Upper limits of $R$ (90$\%$ confidence level) include systematic errors.
We present the midrapidity charged pion invariant cross sections and the ratio of $\pi^-$-to-$\pi^+$ production ($5
Invariant cross section for $\pi^+$ and $\pi^-$ hadrons, as well as the statistical and systematic uncertainties. In addition, there is an absolute scale uncertainty of 9.6$\%$.
Double-helicity asymmetries and statistical uncertainties for $\pi^+$ and $\pi^-$ hadrons. The primary systematic uncertainties, which are fully correlated between points, are $1.4\times10^{-3}$ from relative luminosity and a $^{+7.0\%}_{-7.7\%}$ scaling uncertainty from beam polarization.
Ratio of charged pion cross section, as shown in Fig.6.
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).
A measurement of the transverse momentum spectra of jets in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV is reported. Jets are reconstructed from charged particles using the anti-$k_{\rm T}$ jet algorithm with jet resolution parameters $R$ of $0.2$ and $0.3$ in pseudo-rapidity $|\eta|<0.5$. The transverse momentum $p_{\rm T}$ of charged particles is measured down to $0.15$ GeV/$c$ which gives access to the low $p_{\rm T}$ fragments of the jet. Jets found in heavy-ion collisions are corrected event-by-event for average background density and on an inclusive basis (via unfolding) for residual background fluctuations and detector effects. A strong suppression of jet production in central events with respect to peripheral events is observed. The suppression is found to be similar to the suppression of charged hadrons, which suggests that substantial energy is radiated at angles larger than the jet resolution parameter $R=0.3$ considered in the analysis. The fragmentation bias introduced by selecting jets with a high $p_{\rm T}$ leading particle, which rejects jets with a soft fragmentation pattern, has a similar effect on the jet yield for central and peripheral events. The ratio of jet spectra with $R=0.2$ and $R=0.3$ is found to be similar in Pb-Pb and simulated PYTHIA pp events, indicating no strong broadening of the radial jet structure in the reconstructed jets with $R<0.3$.
Average values of the number of participating nucleons (Npart), number of binary collisions (Ncoll), and the nuclear overlap function (TAA) for the centrality intervals used in the jet analysis.
Charged jet spectra using two cone radius parameters R = 0.2 and 0.3 and a leading track selection of pT > 0.15 GeV, for centrality 0-10%. The two systematic uncertainties correspond to the shape uncertainty and the correlated uncertainty.
Charged jet spectra using two cone radius parameters R = 0.2 and 0.3 and a leading track selection of pT > 0.15 GeV, for centrality 10-30%. The two systematic uncertainties correspond to the shape uncertainty and the correlated uncertainty.
The ratios of yields of anti-baryons to baryons probes the mechanisms of baryon-number transport. Results for $\bar{\rm p}/{\rm p}$, $\bar{\rm \Lambda}/{\rm \Lambda}$, $\rm\bar{\Xi}$$^{+}/{\rm \Xi}^{-}$ and $\rm\bar{\Omega}$$^{+}/{\rm \Omega}^{-}$ in pp collisions at $\sqrt{s} = 0.9$, 2.76 and 7 TeV, measured with the ALICE detector at the LHC, are reported. Within the experimental uncertainties and ranges covered by our measurement, these ratios are independent of rapidity, transverse momentum and multiplicity for all measured energies. The results are compared to expectations from event generators, such as PYTHIA and HIJING-B, that are used to model the particle production in pp collisions. The energy dependence of $\bar{\rm p}/{\rm p}$, $\bar{\rm \Lambda}/{\rm \Lambda}$, $\rm\bar{\Xi}$$^{+}/{\rm \Xi^{-}}$ and $\rm\bar{\Omega}$$^{+}/{\rm \Omega^{-}}$, reaching values compatible with unity for $\sqrt{s} = 7$ TeV, complement the earlier $\bar{\rm p}/{\rm p}$ measurement of ALICE. These dependencies can be described by exchanges with the Regge-trajectory intercept of $\alpha_{\rm {J}} \approx 0.5$, which are suppressed with increasing rapidity interval ${\rm \Delta} y$. Any significant contribution of an exchange not suppressed at large ${\rm \Delta} y$ (reached at LHC energies) is disfavoured.
The pbar/p ratio at sqrt(s) = 2.76 TeV as a function of pT.
The pbar/p ratio at sqrt(s) = 2.76 TeV as a function of rapidity.
The LambdaBar/Lambda ratio at sqrt(s) = 0.9 TeV as a function of pT.
The ALICE collaboration at the CERN Large Hadron Collider reports the first measurement of the inclusive differential jet cross section at mid-rapidity in pp collisions at $\sqrt{s} = 2.76$ TeV, with integrated luminosity of 13.6 nb$^{-1}$. Jets are measured over the transverse momentum range 20 to 125 GeV/c and are corrected to the particle level. Calculations based on Next-to-Leading Order perturbative QCD are in good agreement with the measurements. The ratio of inclusive jet cross sections for jet radii $R = 0.2$ and $R = 0.4$ is reported, and is also well reproduced by a Next-to-Leading Order perturbative QCD calculation when hadronization effects are included.
Inclusive differential jet cross section for R=0.2 and R=0.4.
Ratio of the inclusive differential jet cross section for R=0.2 and R=0.4.
We report the first observation of diffractive $J/\psi(\to \mu^+\mu^-)$ production in $\bar pp$ collisions at $\sqrt{s}$=1.8 TeV. Diffractive events are identified by their rapidity gap signature. In a sample of events with two muons of transverse momentum $p_T^{\mu}>2$ GeV/$c$ within the pseudorapidity region $|\eta|<$1.0, the ratio of diffractive to total $J/\psi$ production rates is found to be $R_{J/\psi}= [1.45\pm 0.25]%$. The ratio $R_{J/\psi}(x)$ is presented as a function of $x$-Bjorken. By combining it with our previously measured corresponding ratio $R_{jj}(x)$ for diffractive dijet production, we extract a value of $0.59\pm 0.15$ for the gluon fraction of the diffractive structure function of the proton.
Diffractive to total J/psi production ratio.
Ratio of diffractive to total J/psi rate, per unit of the fractional momentum loss of the leading (anti)proton, and as a function of x-Bjorken of the struck parton of the (anti)proton adjacent to the rapidity gap and participating in the J/psi production.
Gluon fraction of the diffractive structure function of the (anti)proton.
We have measured the ratio of prompt production rates of the charmonium states χc1 and χc2 in 110pb−1 of pp¯ collisions at s=1.8TeV. The photon from their decay into J/ψγ is reconstructed through conversion into e+e− pairs. The energy resolution this technique provides makes the resolution of the two states possible. We find the ratio of production cross sections σχc2σχc1=0.96±0.27(stat)±0.11(syst) for events with pT(J/ψ)>4.0GeV/c, |η(J/ψ)|<0.6, and pT(γ)>1.0GeV/c.
No description provided.
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