Mon·May 20, 2019Monday·May 20, 2019

1. 01*

   Production of muons from heavy-flavour hadron decays in pp collisions at $\sqrt{s}$ = 5.02 TeV

   ALICE Collaboration

   Production cross sections of muons from semi-leptonic decays of charm and beauty hadrons were measured at forward rapidity ($2.5<y<4$) in proton--proton (pp) collisions at a centre-of-mass energy $\sqrt{s}=5.02$ TeV with the ALICE detector at the CERN LHC. The results were obtained in an extended transverse momentum interval, $2<p_{\mathrm{T}}<20$ GeV/$c$, and with an improved precision compared to previous measurements performed in the same rapidity interval at centre-of-mass energies $\sqrt{s}=2.76$ and 7 TeV. The $p_{\mathrm{T}}$- and $y$-differential production cross sections as well as the $p_{\mathrm{T}}$-differential production cross section ratios between different centre-of-mass energies and different rapidity intervals are described, within experimental and theoretical uncertainties, by predictions based on perturbative QCD.

   nucl-exhep-exJHEP(2019)·31 citations
2. 02*

   Charged-particle production as a function of multiplicity and transverse spherocity in pp collisions at $\sqrt{s}$ = 5.02 and 13 TeV

   ALICE Collaboration

   We present a study of the inclusive charged-particle transverse momentum ($p_{\mathrm{T}}$) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, $\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta$, in pp collisions at $\sqrt{s}$ = 5.02 and 13 TeV covering the kinematic range $|\eta |<0.8$ and $0.15<p_{\mathrm{T}}<20$ GeV/$c$. The results are presented for events with at least one charged particle in $|\eta |<1$ (INEL$>0$). The $p_{\mathrm{T}}$ spectra are reported for two multiplicity estimators covering different pseudorapidity regions. The $p_{\mathrm{T}}$ spectra normalized to that for INEL $>0$ show little energy dependence. Moreover, the high-$p_{\mathrm{T}}$ yields of charged particles increase faster than the charged-particle multiplicity density. The average $p_{\mathrm{T}}$ as a function of multiplicity and transverse spherocity is reported for pp collisions at $\sqrt{s}=13$ TeV. For low- (high-) spherocity events, corresponding to jet-like (isotropic) events, the average $p_{\mathrm{T}}$ is higher (smaller) than that measured in INEL $>0$ pp collisions. Within uncertainties, the functional form of $⟨p_{\mathrm{T}}⟩(N_{\mathrm{ch}})$ is not affected by the spherocity selection. While EPOS LHC gives a good description of many features of data, PYTHIA overestimates the average $p_{\mathrm{T}}$ in jet-like events.

   nucl-exhep-exEPJC(2019)·159 citations
3. 03*

   Study of the $\Lambda$-$\Lambda$ interaction with femtoscopy correlations in pp and p-Pb collisions at the LHC

   ALICE Collaboration

   This work presents new constraints on the existence and the binding energy of a possible $\Lambda$-$\Lambda$ bound state, the H-dibaryon, derived from $\Lambda$-$\Lambda$ femtoscopic measurements by the ALICE collaboration. The results are obtained from a new measurement using the femtoscopy technique in pp collisions at $\sqrt{s}=13$ TeV and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, combined with previously published results from p-Pb collisions at $\sqrt{s}=7$ TeV. The $\Lambda$-$\Lambda$ scattering parameter space, spanned by the inverse scattering length $f_0^{-1}$ and the effective range $d_0$, is constrained by comparing the measured $\Lambda$-$\Lambda$ correlation function with calculations obtained within the Lednicky model. The data are compatible with hypernuclei results and lattice computations, both predicting a shallow attractive interaction, and permit to test different theoretical approaches describing the $\Lambda$-$\Lambda$ interaction. The region in the $(f_0^{-1},d_0)$ plane which would accommodate a $\Lambda$-$\Lambda$ bound state is substantially restricted compared to previous studies. The binding energy of the possible $\Lambda$-$\Lambda$ bound state is estimated within an effective-range expansion approach and is found to be $B_{\Lambda \Lambda }=3.2_{-2.4}^{+1.6}{(\mathrm{stat})}_{-1.0}^{+1.8}(\mathrm{syst})$ MeV.

   nucl-exhep-exPLB(2019)·158 citations
4. 04*

   Inclusive J/$\psi$ production at mid-rapidity in pp collisions at $\sqrt{s}$ = 5.02 TeV

   ALICE Collaboration

   Inclusive J/$\psi$ production is studied in minimum-bias proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 5.02 TeV by ALICE at the CERN LHC. The measurement is performed at mid-rapidity ($|y|<0.9$) in the dielectron decay channel down to zero transverse momentum $p_{\mathrm{T}}$, using a data sample corresponding to an integrated luminosity of $L_{\mathrm{int}}=19.4\pm$ 0.4 nb${}^{-1}$. The measured $p_{\mathrm{T}}$-integrated inclusive J/$\psi$ production cross section is d$\sigma$/d$y$ = 5.64 $\pm$ 0.22 (stat.) $\pm 0.33$ (syst.) $\pm 0.12$ (lumi.) $\mu$b. The $p_{\mathrm{T}}$-differential cross section d${}^2\sigma$/d$p_{\mathrm{T}}$d$y$ is measured in the $p_{\mathrm{T}}$ range 0$-$10 GeV/$c$ and compared with state-of-the-art QCD calculations. The J/$\psi$ $⟨p_{\mathrm{T}}⟩$ and $⟨p_{\mathrm{T}}^2⟩$ are extracted and compared with results obtained at other collision energies.

   nucl-exhep-exJHEP(2019)·72 citations
5. 05*

   Kaon Multiplicities of Semi-inclusive DIS and the Fragmentation Functions

   Chung Wen Kao🇹🇼 · Dong Jing Yang🇹🇼 · Wen Chen Chang🇹🇼

   There is an apparent discrepancy between the results of the charged kaon multiplicities off the deuteron target from HERMES and COMPASS experiments. In this article we point out that this discrepancy cannot be explained by different $Q^2$ values. Furthermore we examine the empirical parametrization of the fragmentation functions, DSS2017 carefully and find that the agreement between the theoretical estimate and the HERMES data is less satisfactory as claimed.

   ↳ hep-phhep-exnucl-exJPS Conf.Proc.(2019)·0 citations
6. 06*

   Spin determination from the in-plane angular correlation analysis for various coordinate systems

   Biao Yang🇨🇳 · Yan-Lin Ye🇨🇳 · Jian-Ling Lou🇨🇳 · Xiao-Fei Yang🇨🇳 · Jing-Jing Li🇰🇷 · Yang Liu🇨🇳 · Wei Liu🇨🇳 · HanZhou Yu

   In a reaction to excite the resonant state followed by the sequential cluster-decay, the in-plane angular correlation method is usually applied to determine the spin of the mother nucleus. However, the correlation pattern exhibited in a two-dimensional angular-correlation spectrum depends on the selected coordinate system. Particularly the parity-symmetric and the axial-symmetric processes should be presented in a way to enhance the correlation pattern whereas the non-symmetric process should be plotted elsewhere in order to reduce the correlation background. In this article, three possible coordinate systems, which were previously adopted in the literature, are described and compared to each other. The consistency of these systems is evaluated based on the real experimental data analysis for the 10.29-MeV state in ${}^{18}$O. A spin-parity of 4${}^{+}$ is obtained for all three coordinate systems.

   ↳ physics.data-annucl-exCPC(2019)·5 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.