The transverse polarization of $\Lambda$ and $\bar\Lambda$ hyperons produced in proton-proton collisions at a center-of-mass energy of 7 TeV is measured. The analysis uses 760 $\mu$b$^{-1}$ of minimum bias data collected by the ATLAS detector at the LHC in the year 2010. The measured transverse polarization averaged over Feynman $x_{\rm F}$ from $5\times 10^{-5}$ to 0.01 and transverse momentum $p_{\rm T}$ from 0.8 to 15 GeV is $-0.010 \pm 0.005({\rm stat}) \pm 0.004({\rm syst})$ for $\Lambda$ and $0.002 \pm 0.006({\rm stat}) \pm 0.004({\rm syst})$ for $\bar\Lambda$. It is also measured as a function of $x_{\rm F}$ and $p_{\rm T}$, but no significant dependence on these variables is observed. Prior to this measurement, the polarization was measured at fixed-target experiments with center-of-mass energies up to about 40 GeV. The ATLAS results are compatible with the extrapolation of a fit from previous measurements to the $x_{\rm F}$ range covered by this mesurement.
Transverse polarization POL of LAMBDA and LAMBDABAR hyperons averaged over PT and XF.
Transverse polarization POL of LAMBDA and LAMBDABAR hyperons as a function of XF.
Transverse polarization POL of LAMBDA and LAMBDABAR hyperons as a function of PT.
Production of $B_c^+$ mesons in proton-proton collisions at a center-of-mass energy of 8 TeV is studied with data corresponding to an integrated luminosity of $2.0~{\rm fb}^{-1}$ recorded by the LHCb experiment. The ratio of production cross-sections times branching fractions between the $B_c^+\to J/\psi \pi^+$ and $B^+\to J/\psi K^+$ decays is measured as a function of transverse momentum and rapidity in the regions $0 < p_{\rm T} < 20~{\rm GeV}/c$ and $2.0 < y < 4.5$. The ratio in this kinematic range is measured to be $(0.683\pm0.018\pm0.009)\%$, where the first uncertainty is statistical and the second systematic.
Double differential production ratio $R(p_T, y)$ in bins of $p_T$ and $y$.
Differential production ratio $R(p_T)$ in bins of $p_T$ and integrated over $2.0 < y <4.5$ range.
Differential production ratio $R(y)$ in bins of $y$ and integrated over $0 < p_T < 20$ $GeV/c$ range.
We present the analysis of the inclusive $K^{0}$ production in p+p and p+Nb collisions measured with the HADES detector at a beam kinetic energy of 3.5 GeV. Data are compared to the GiBUU transport model. The data suggest the presence of a repulsive momentum-dependent kaon potential as predicted by the Chiral Perturbation Theory (ChPT). For the kaon at rest and at normal nuclear density, the ChPT potential amounts to $\approx 35$ MeV. A detailed tuning of the kaon production cross sections implemented in the model has been carried out to reproduce the experimental data measured in p+p collisions. The uncertainties in the parameters of the model were examined with respect to the sensitivity of the experimental results from p+Nb collisions to the in-medium kaon potential.
The K0 production cross section in P P collisions.
The K0 production cross section in P + NB collisions. The uncertainty given on SIG(P NB --> K0 X) is the dominating absolute normalization uncertainty.
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.
A measurement is presented of the phi to K+K- production cross section at sqrt(s) = 7 TeV using pp collision data corresponding to an integrated luminosity of 383 mub-1, collected with the ATLAS experiment at the LHC. Selection of phi(1020) mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section is measured as a function of the transverse momentum, pTphi, and rapidity, |yphi|, of the phi(1020) meson in the fiducial region 500 < pTphi< 1200 MeV, |yphi| < 0.8, kaon pTK> 230 MeV and kaon momentum pK< 800 MeV.The integrated phi(1020)-meson production cross section in this fiducial range is measured to be s(phi K+K-) = 570 pm 8 (stat) pm 66 (syst) pm 20 (lumi) mub.
The differential PHI(1020) meson production cross section measured in the fiducial region as a function of the PHI(1020) transverse momentum.
The differential PHI(1020) meson production cross section measured in the fiducial region as a function of the PHI(1020) rapidity.
The integrated PHI(1020) meson production cross section in the fiducial region.
We report measurements of the inclusive transverse momentum pT distribution of centrally produced kshort, kstar(892), and phi(1020) mesons up to pT = 10 GeV/c in minimum-bias events, and kshort and lambda particles up to pT = 20 GeV/c in jets with transverse energy between 25 GeV and 160 GeV in pbar p collisions. The data were taken with the CDF II detector at the Fermilab Tevatron at sqrt(s) = 1.96 TeV. We find that as pT increases, the pT slopes of the three mesons (kshort, kstar, and phi) are similar, and the ratio of lambda to kshort as a function of pT in minimum-bias events becomes similar to the fairly constant ratio in jets at pT ~ 5 GeV/c. This suggests that the particles with pT >~ 5 GeV/c in minimum-bias events are from soft jets, and that the pT slope of particles in jets is insensitive to light quark flavor (u, d, or s) and to the number of valence quarks. We also find that for pT <~ 4 GeV relatively more lambda baryons are produced in minimum-bias events than in jets.
The inclusive invariant differential cross section for K0S production.
The inclusive invariant differential cross section for PHI production.
The inclusive invariant differential cross section for K*(892)+- production.
The production cross-section of B+ mesons is measured as a function of transverse momentum pT and rapidity y in proton--proton collisions at center-of-mass energy sqrt(s) = 7 TeV, using 2.4 fb-1 of data recorded with the ATLAS detector at the Large Hadron Collider. The differential production cross-sections, determined in the range 9<pT<120 GeV and y<2.25, are compared to next-to-leading-order theoretical predictions.
Differential cross-section measurement for B+ production multiplied by the branching ratio to the J/PSI < MU+ MU- > K+ final state in B+ pT intervals in the B+ rapidity range |y|<0.5. The first quoted uncertainty is statistical, the second uncertainty is systematic.
Differential cross-section measurement for B+ production multiplied by the branching ratio to the J/PSI < MU+ MU- > K+ final state in B+ pT intervals in the B+ rapidity range 0.5<|y|<1. The first quoted uncertainty is statistical, the second uncertainty is systematic.
Differential cross-section measurement for B+ production multiplied by the branching ratio to the J/PSI < MU+ MU- > K+ final state in B+ pT intervals in the B+ rapidity range 1<|y|<1.5 The first quoted uncertainty is statistical, the second uncertainty is systematic.
Inclusive production cross sections of $\pi^\pm$, $K^\pm$ and $p\bar{p}$ per hadronic $e^+e^-$ annihilation event in $e^+e^-$ are measured at a center-of-mass energy of 10.54 GeV, using a relatively small sample of very high quality data from the BaBar experiment at the PEP-II $B$-factory at the SLAC National Accelerator Laboratory. The drift chamber and Cherenkov detector provide clean samples of identified $\pi^\pm$, $K^\pm$ and $p\bar{p}$ over a wide range of momenta. Since the center-of-mass energy is below the threshold to produce a $B\bar{B}$ pair, with $B$ a bottom-quark meson, these data represent a pure $e^+e^- \rightarrow q\bar{q}$ sample with four quark flavors, and are used to test QCD predictions and hadronization models. Combined with measurements at other energies, in particular at the $Z^0$ resonance, they also provide precise constraints on the scaling properties of the hadronization process over a wide energy range.
Differential cross section for prompt PI+-, K+- and PBAR/P production.
Differential cross section for conventional PI+-, K+- and PBAR/P production.
Integrated cross sections for prompt PI+-, K+- and PBAR/P production. The second (sys) error is the uncertainty due to the model dependence of the extrapolation.
We report the exclusive photoproduction cross sections for the Sigma(1385), Lambda(1405), and Lambda(1520) in the reactions gamma + p -> K+ + Y* using the CLAS detector for energies from near the respective production thresholds up to a center-of-mass energy W of 2.85 GeV. The differential cross sections are integrated to give the total exclusive cross sections for each hyperon. Comparisons are made to current theoretical models based on the effective Lagrangian approach and fitted to previous data. The accuracy of these models is seen to vary widely. The cross sections for the Lambda(1405) region are strikingly different for the Sigma+pi-, Sigma0 pi0, and Sigma- pi+ decay channels, indicating the effect of isospin interference, especially at W values close to the threshold.
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Charm production at the LHC in pp collisions at sqrt(s)=7 TeV is studied with the LHCb detector. The decays D0 -> K- pi+, D+ -> K- pi+ pi+, D*+ -> D0(K- pi+) pi+, D_s+ -> phi(K- K+) pi+, Lambda_c+ -> p K- pi+, and their charge conjugates are analysed in a data set corresponding to an integrated luminosity of 15 nb^{-1}. Differential cross-sections dsigma/dp_T are measured for prompt production of the five charmed hadron species in bins of transverse momentum and rapidity in the region 0 < p_T < 8 GeV/c and 2.0 < y < 4.5. Theoretical predictions are compared to the measured differential cross-sections. The integrated cross-sections of the charm hadrons are computed in the above p_T-y range, and their ratios are reported. A combination of the five integrated cross-section measurements gives sigma(c\bar{c})_{p_T < 8 GeV/c, 2.0 < y < 4.5} = 1419 +/- 12 (stat) +/- 116 (syst) +/- 65 (frag) microbarn, where the uncertainties are statistical, systematic, and due to the fragmentation functions.
Differential production cross-sections with respect to transverse momentum, dsigma / dp_T, of Lambda_c+ baryons or their charge conjugates in proton-proton collisions at center-of-mass (CM) energy sqrt(s) = 7 TeV. Measured in bins of hadron transverse momentum (p_T) and rapidity (y) with respect to the beam axis, where p_T and y are measured in the CM frame. Contributions of charm hadrons from the decays of b-hadrons have been removed.
Differential production cross-sections with respect to transverse momentum, dsigma / dp_T, of D0 mesons or their charge conjugates in proton-proton collisions at center-of-mass (CM) energy sqrt(s) = 7 TeV. Measured in bins of hadron transverse momentum (p_T) and rapidity (y) with respect to the beam axis, where p_T and y are measured in the CM frame. Contributions of charm hadrons from the decays of b-hadrons have been removed.
Differential production cross-sections with respect to transverse momentum, dsigma / dp_T, of D+ mesons or their charge conjugates in proton-proton collisions at center-of-mass (CM) energy sqrt(s) = 7 TeV. Measured in bins of hadron transverse momentum (p_T) and rapidity (y) with respect to the beam axis, where p_T and y are measured in the CM frame. Contributions of charm hadrons from the decays of b-hadrons have been removed.
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