The measurement of the production of ${\rm f}_{0}(980)$ in inelastic pp collisions at $\sqrt{s} = 5.02$ TeV is presented. This is the first reported measurement of inclusive ${\rm f}_{0}(980)$ yield at LHC energies. The production is measured at midrapidity, $|y| < 0.5$, in a wide transverse momentum range, $0 < p_{\rm T} < 16$ GeV/$c$, by reconstructing the resonance in the ${\rm f}_{0}(980) \rightarrow \pi^{+}\pi^{-}$ hadronic decay channel using the ALICE detector. The $p_{\rm T}$-differential yields are compared to those of pions, protons and $\phi$ mesons as well as to predictions from the HERWIG 7.2 QCD-inspired Monte Carlo event generator and calculations from a coalescence model that uses the AMPT model as an input. The ratio of the $p_{\rm T}$-integrated yield of ${\rm f}_{0}(980)$ relative to pions is compared to measurements in ${\rm e}^{+}{\rm e}^{-}$ and pp collisions at lower energies and predictions from statistical hadronisation models and HERWIG 7.2. A mild collision energy dependence of the ${\rm f}_{0}(980)$ to pion production is observed in pp collisions from SPS to LHC energies. All considered models underpredict the $p_{\rm T}$-integrated $2{\rm f}_{0}(980)/(\pi^{+}+\pi^{-})$ ratio. The prediction from the canonical statistical hadronisation model assuming a zero total strangeness content of ${\rm f}_{0}(980)$ is consistent with the data within 1.9$\sigma$ and is the closest to the data. The results provide an essential reference for future measurements of the particle yield and nuclear modification in p$-$Pb and Pb$-$Pb collisions, which have been proposed to be instrumental to probe the elusive nature and quark composition of the ${\rm f}_{0}(980)$ scalar meson.
$p_{\rm T}$-differential yields of $f_{0}(980)$ at midrapidity in the inelastic pp collisions at $\sqrt(s)$ = 5.02 TeV. The uncertainty 'syst' indicates the total systematic uncertainty and 'stat' indicates the statistical uncertainty. The branching ratio correction amounts to BR = (46 $\pm$ 6)% [ Phys. Rev. Lett. 111 no. 6, (2013) 062001] assuming dominance of $\pi\pi$ and KK channel has been applied to the $p_{\rm T}$-differential yields of $f_{0}(980)$. The normalisation and branching ratio relative uncertainties on the yields are independent of $p_{\rm{T}}$ and amount to 2.5% and 13%, respectively and therefore not included in the $p_{\rm T}$-differential yields of $f_{0}(980)$.
$p_{\rm T}$-integrated yield of $f_{0}(980)$, dN/dy at midrapidity as a function of $\langle {\rm d}N_{\rm ch}/{\rm d}\eta \rangle$. The uncertainty 'syst' indicates the total systematic uncertainty on the measurement. The branching ratio correction amounts to BR = (46 $\pm$ 6)% [ Phys. Rev. Lett. 111 no. 6, (2013) 062001] assuming dominance of $\pi\pi$ and KK channel has been applied to the $p_{\rm T}$-differential yields of $f_{0}(980)$. Here, the branching ratio relative uncertainty (13%) for $f_{0}(980)$ is not included.
mean-$p_{\rm{T}}$ of $f_{0}(980)$, (<$p_{\rm{T}}$>) at midrapidity as a function of $\langle {\rm d}N_{\rm ch}/{\rm d}\eta \rangle$. The uncertainty 'syst' indicates the total systematic uncertainty on the measurement.
The cross section of top quark pair production is measured in the $\mathrm{t\bar{t}}\to (\ell\nu_{\ell})(\tau_\mathrm{h}\nu_{\tau})\mathrm{b\bar{b}}$ final state, where $\tau_\mathrm{h}$ refers to the hadronic decays of the $\tau$ lepton, and $\ell$ is either an electron or a muon. The data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$ collected in proton-proton collisions at $\sqrt{s}=$ 13 TeV with the CMS detector. The measured cross section is $\sigma_{\mathrm{t\bar{t}}} =$ 781 $\pm$ 7 (stat) $\pm$ 62 (syst) $\pm$ 20 (lum) pb, and the ratio of the partial width $\Gamma($t$\to\tau\nu_{\tau}$b) to the total decay width of the top quark is measured to be 0.1050 $\pm$ 0.0009 (stat) $\pm$ 0.0071 (syst). This is the first measurement of the $\mathrm{t\bar{t}}$ production cross section in proton-proton collisions at $\sqrt{s}=$ 13 TeV that explicitly includes $\tau$ leptons. The ratio of the cross sections in the $\ell\tau_\mathrm{h}$ and $\ell\ell$ final states yields a value $R_{\ell\tau_\mathrm{h}/\ell\ell}=$ 0.973 $\pm$ 0.009 (stat) $\pm$ 0.066 (syst), consistent with lepton universality.
The measured inclusive top quark pair production cross section in the dilepton final state with one tau lepton.
The ratio between top quark production cross sections measured in lepton-tau and light dilepton final states.
The ratio of the partial width to the total decay width of the top quark.
The production yield of the $\Lambda(1520)$ baryon resonance is measured at mid-rapidity in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV with the ALICE detector at the LHC. The measurement is performed in the $\Lambda(1520)\rightarrow {\rm pK}^{-}$ (and charge conjugate) hadronic decay channel as a function of the transverse momentum ($p_{\rm T}$) and collision centrality. The $p_{\rm T}$-integrated production rate of $\Lambda(1520)$ relative to $\Lambda$ in central collisions is suppressed by about a factor of 2 with respect to peripheral collisions. This is the first observation of the suppression of a baryonic resonance at LHC and the first evidence of $\Lambda(1520)$ suppression in heavy-ion collisions. The measured $\Lambda(1520)/\Lambda$ ratio in central collisions is smaller than the value predicted by the statistical hadronisation model calculations. The shape of the measured $p_{\rm T}$ distribution and the centrality dependence of the suppression are reproduced by the EPOS3 Monte Carlo event generator. The measurement adds further support to the formation of a dense hadronic phase in the final stages of the evolution of the fireball created in heavy-ion collisions, lasting long enough to cause a significant reduction in the observable yield of short-lived resonances.
$p_{\rm T}$-differential yields of $\Lambda$(1520) (sum of particle and anti-particle states) at midrapidity in the 0-20% centrality class. The uncertainty 'syst,uncorrelated' indicates the systematic uncertainty after removing the contributions common to all centrality classes
$p_{\rm T}$-differential yields of $\Lambda$(1520) (sum of particle and anti-particle states) at midrapidity in the 20-50% centrality class. The uncertainty 'syst,uncorrelated' indicates the systematic uncertainty after removing the contributions common to all centrality classes
$p_{\rm T}$-differential yields of $\Lambda$(1520) (sum of particle and anti-particle states) at midrapidity in the 50-80% centrality class. The uncertainty 'syst,uncorrelated' indicates the systematic uncertainty after removing the contributions common to all centrality classes
Four-lepton production in proton-proton collisions, pp to (Z/gamma*)(Z/gamma*) to l+l-l'+l'-, where l, l' = e or mu, is studied at a center-of-mass energy of 13 TeV with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 2.6 inverse femtobarns. The ZZ production cross section, sigma(pp to ZZ) = 14.6 +1.9/-1.8 (stat) +0.5/-0.3 (syst) +/- 0.2 (theo) +/- 0.4 (lumi) pb, is measured for events with two opposite-sign, same-flavor lepton pairs produced in the mass region 60 < m[l+l-], m[l'+l'-] < 120 GeV. The Z boson branching fraction to four leptons is measured to be B(Z to l+l-l'+l'-) = 4.9 +0.8/-0.7 (stat) +0.3/-0.2 (syst) +0.2/-0.1 (theo) +/- 0.1 (lumi) x E-6 for the four-lepton invariant mass in the range 80 < m[l+l-l'+l'-] < 100 GeV and dilepton mass m[l+l-] > 4 GeV for all opposite-sign, same-flavor lepton pairs. The results are in agreement with standard model predictions.
The (P P to Z Z to l+l-l'+l'-) fiducial cross section. The first systematic uncertainty is detector systematics, the second is luminosity uncertainty. The theoretical prediction is POWHEG generated at NLO plus the gluon-gluon initial state contribution from MCFM, using NNPDF3.0 PDFs and scales mu_F = mu_R = 0.5m[l+l-l'+l'-].
The (P P to Z to l+l-l'+l'-) fiducial cross section. The first systematic uncertainty is detector systematics, the second is luminosity uncertainty. The theoretical prediction is POWHEG generated at NLO using NNPDF3.0 PDFs and scales mu_F = mu_R = m[l+l-l'+l'-].
The total (P P to Z) cross section times the (Z to l+l-l'+l'-) branching ratio. The first systematic uncertainty is detector systematics, the second is theoretical uncertainty, and the third is luminosity uncertainty.
The first direct measurement of electron-neutrino quasielastic and quasielastic-like scattering on hydrocarbon in the few-GeV region of incident neutrino energy has been carried out using the MINERvA detector in the NuMI beam at Fermilab. The flux-integrated differential cross sections in electron production angle, electron energy and $Q^{2}$ are presented. The ratio of the quasielastic, flux-integrated differential cross section in $Q^{2}$ for $\nu_{e}$ with that of similarly-selected $\nu_{\mu}$-induced events from the same exposure is used to probe assumptions that underpin conventional treatments of charged-current $\nu_{e}$ interactions used by long-baseline neutrino oscillation experiments. The data are found to be consistent with lepton universality and are well-described by the predictions of the neutrino event generator GENIE.
The $\nu_{e}+\bar{\nu}_{e}$ flux as a function of neutrino energy from the beam simulation for the data used in this analysis. The $\bar{\nu}_{e}$ fraction is shown separately to emphasize the dominance of $\nu_{e}$ in the sum.
Flux-integrated differential $\nu_{e}$ CCQE-like cross section versus electron energy.
Covariance matrix for flux-integrated differential $\nu_{e}$ CCQE-like cross section versus electron energy.
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A search is described for a Higgs boson decaying into two photons, one of which has an internal conversion to a muon or an electron pair (ll gamma). The analysis is performed using proton-proton collision data recorded with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 inverse femtobarns. The events selected have an opposite-sign muon or electron pair and a high transverse momentum photon. No excess above background has been found in the three-body invariant mass range 120 < m[ll gamma] < 150 GeV, and limits have been derived for the Higgs boson production cross section times branching fraction for the decay H to gamma* gamma to ll gamma, where the dilepton invariant mass is less than 20 GeV. For a Higgs boson with m[H] = 125 GeV, a 95% confidence level (CL) exclusion observed (expected) limit is 6.7 (5.9 +2.8/-1.8) times the standard model prediction. Additionally, an upper limit at 95% CL on the branching fraction of H to J/Psi gamma for the 125 GeV Higgs boson is set at 1.5E-3.
The 95% CL exclusion limit, as a function of the mass hypothesis, $m_H$ , on $\sigma/\sigma_{SM}$, the cross section times the branching fraction of a Higgs boson decaying into a photon and a lepton pair with $m_{\ell\ell}$ < 20 GeV, divided by the SM value.
The 95% CL exclusion limit, as a function of the mass hypothesis, $m_H$ , on $\sigma/\sigma_{SM}$, the cross section times the branching fraction of a Higgs boson decaying into a photon and a lepton pair with $m_{\ell\ell}$ < 20 GeV, divided by the SM value.
The 95% CL exclusion limit, as a function of the mass hypothesis, $m_H$ , on $\sigma/\sigma_{SM}$, the cross section times the branching fraction of a Higgs boson decaying into a photon and a lepton pair with $m_{\ell\ell}$ < 20 GeV, divided by the SM value.
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 final results of a measurement of the polarization parameter P 0 in high-energy n~-p and p-p elastic scattering, performed using a target which contained polarized protons. Data were taken at beam momenta of 6.0, 8.0, 10.0 and 12.0 GeV/c for n-, and of 6.0, 10.0 and 12.0 GeV/c for n+ and p, in the interval of invariant four-momentum transfer squared-t from 0.1 to 0.75 (GeV/c)2.
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