Correlation of theoretical uncertainties in PDF fits and theoretical uncertainties in predictions

We show how to account for correlations between theoretical uncertainties incorporated in parton distribution function (PDF) fits, and the theoretical uncertainties in the predictions made using these PDFs. We demonstrate by explicit calculations, both analytical and numerical, that these correlations can lead to corrections to the central values of the predictions, and reductions in both the PDF uncertainties and the theoretical uncertainties in the prediction. We illustrate our results with predictions for top production rapidity distributions and the Higgs total cross-section at the LHC, using the NLO NNPDF3.1 PDF set which incorporates missing higher order uncertainties. We conclude that the inclusion of correlations can increase both the accuracy and precision of predictions involving PDFs, particularly for processes with data already included in the PDF fit.

Investigation of exotic state X(3872) in pp collisions at $$\sqrt{s}=7$$, 13 TeV

We have used the dynamically constrained phase space coalescence model to study the production of the exotic state X(3872) based on the hadronic final states generated by the parton and hadron cascade model (PACIAE) with $$|y|<1$$ | y | < 1 and $$p_T < 15.5$$ p T < 15.5 GeV/c in pp collisions at $$\sqrt{s}=7$$ s = 7 and 13 TeV, respectively. Here the X(3872) is assumed to consist of bound state $$D\bar{D^*}$$ D D ∗ ¯ , which can form three possible structures for the tetraquark state, the nucleus-like state, and the molecular state. The yields of three different structures X(3872) were predicted. The transverse momentum distribution and the rapidity distribution of three different structures X(3872) are also presented. Sizable difference can be found in the transverse momentum and rapidity distributions for the three different X(3872) structures.

High-energy resummation in $$\Lambda _c$$ baryon production

We present a study on inclusive emissions of a double $$\Lambda _c$$ Λ c or of a $$\Lambda _c$$ Λ c plus a light-flavored jet system as probe channels in the semi-hard regime of QCD. Our formalism relies on the so-called hybrid high-energy/collinear factorization, where the standard collinear description is supplemented by the t-channel resummation à la BFKL of energy logarithms up to the next-to-leading accuracy. We make use of the modular interface, suited to the analysis of different semi-hard reactions, employing the novel parameterization for the description of parton fragmentation into $$\Lambda _c$$ Λ c baryons. We provide predictions for rapidity distributions and azimuthal correlations, that can be studied at current and forthcoming LHC configurations, hunting for possible stabilizing effects of the high-energy series.

Energy dependence of $$\phi $$ meson production at forward rapidity in pp collisions at the LHC

The production of $$\phi $$ ϕ mesons has been studied in pp collisions at LHC energies with the ALICE detector via the dimuon decay channel in the rapidity region $$2.5< y < 4$$ 2.5 < y < 4 . Measurements of the differential cross section $$\mathrm{d}^2\sigma /\mathrm{d}y \mathrm{d}p_{\mathrm {T}}$$ d 2 σ / d y d p T are presented as a function of the transverse momentum ($$p_{\mathrm {T}}$$ p T ) at the center-of-mass energies $$\sqrt{s}=5.02$$ s = 5.02 , 8 and 13 TeV and compared with the ALICE results at midrapidity. The differential cross sections at $$\sqrt{s}=5.02$$ s = 5.02 and 13 TeV are also studied in several rapidity intervals as a function of $$p_{\mathrm {T}}$$ p T , and as a function of rapidity in three $$p_{\mathrm {T}}$$ p T intervals. A hardening of the $$p_{\mathrm {T}}$$ p T -differential cross section with the collision energy is observed, while, for a given energy, $$p_{\mathrm {T}}$$ p T spectra soften with increasing rapidity and, conversely, rapidity distributions get slightly narrower at increasing $$p_{\mathrm {T}}$$ p T . The new results, complementing the published measurements at $$\sqrt{s}=2.76$$ s = 2.76 and 7 TeV, allow one to establish the energy dependence of $$\phi $$ ϕ meson production and to compare the measured cross sections with phenomenological models. None of the considered models manages to describe the evolution of the cross section with $$p_{\mathrm {T}}$$ p T and rapidity at all the energies.

Probing charmonium-like XYZ states in hadron–hadron ultraperipheral collisions and electron–proton scattering

Exclusive production of charmonium-like XYZ states in hadron–hadron ultraperipheral collisions (UPCs) and electron–proton scattering are studied employing the effective Lagrangian method. Total cross sections and rapidity distributions of charmonium-like XYZ states are obtained in hadron–hadron UPCs and the electron–proton scattering process. These predictions can be applied to estimate the observed event number of exclusive charmonium-like XYZ states in hadron–hadron UPCs and electron–proton scattering. The results indicate that it is significant to search X(3872) and $$Z^+_c(3900)$$ Z c + ( 3900 ) in pA UPCs, and the Electron–Ion Collider in China will be an advantageous platform to observe XYZ states in the future.

Higher-order corrections for tW production at high-energy hadron colliders

We discuss cross sections for tW production in proton-proton collisions at the LHC and at higher-energy colliders with energies of up to 100 TeV. We find that, remarkably, the soft-gluon corrections are numerically dominant even at very high collider energies. We present results with soft-gluon corrections at approximate NNLO and approximate N3LO matched to complete NLO results. These higher-order corrections are large and need to be included for better theoretical accuracy and smaller scale dependence. Total cross sections as well as top-quark and W-boson transverse-momentum and rapidity distributions are presented using various recent sets of parton distribution functions.

The study of exotic state $$Z_c^{\pm }(3900)$$ decaying to $$J/\psi \pi ^{\pm }$$ in the pp collisions at $$\sqrt{s}$$ = 1.96, 7, and 13 TeV

A dynamically constrained phase-space coalescence model and PACIAE model are used to predict the exotic resonant state $$Z_c^{\pm }(3900)$$ Z c ± ( 3900 ) yield in pp collisions at $$\sqrt{s} = 1.96, 7$$ s = 1.96 , 7 and 13 TeV, respectively, which are estimated to be around $$10^{-6}$$ 10 - 6 to $$10^{-5}$$ 10 - 5 based on the $$J/\psi \pi ^{\pm }$$ J / ψ π ± bound state in the decay chain of b hadrons. The energy dependence of the transverse momentum distributions and rapidity distributions with $$|y|<6$$ | y | < 6 and $$p_{T}<10$$ p T < 10 GeV/c are also calculated for $${Z_c^{+}(3900)}$$ Z c + ( 3900 ) and $${Z_c^{-}(3900)}$$ Z c - ( 3900 ) . The production of $${Z_c^{+}(3900)}$$ Z c + ( 3900 ) and its anti-particle $${Z_c^{-}(3900)}$$ Z c - ( 3900 ) are found to be quite similar to each other.

Measurements of $$\pi ^\pm $$, $$K^\pm $$, p and $$\bar{p}$$ spectra in $$^7$$Be+$$^9$$Be collisions at beam momenta from 19A to 150A $${\mathrm{Ge} \mathrm{V}}\!/\!c$$ with the NA61/SHINE spectrometer at the CERN SPS

The NA61/SHINE experiment at the CERN Super Proton Synchrotron (SPS) studies the onset of deconfinement in hadron matter by a scan of particle production in collisions of nuclei with various sizes at a set of energies covering the SPS energy range. This paper presents results on inclusive double-differential spectra, transverse momentum and rapidity distributions and mean multiplicities of $$\pi ^\pm $$ π ± , $$K^\pm $$ K ± , p and $$\bar{p}$$ p ¯ produced in the 20% most central$$^7$$ 7 Be+$$^9$$ 9 Be collisions at beam momenta of 19A, 30A, 40A, 75A and 150A $${\mathrm{Ge} \mathrm{V}}\!/\!c$$ Ge V / c . The energy dependence of the $$K^\pm $$ K ± /$$\pi ^\pm $$ π ± ratios as well as of inverse slope parameters of the $$K^\pm $$ K ± transverse mass distributions are close to those found in inelastic p+p reactions. The new results are compared to the world data on p+p and Pb+Pb collisions as well as to predictions of the Epos, Urqmd, Ampt, Phsd and Smash models.