Related papers: Precise charm-quark mass from deep-inelastic scatt…
We investigate the invariant-mass distribution of top-quark pairs near the $2m_t$ threshold, which has strong impact on the determination of the top-quark mass $m_t$. We show that higher-order non-relativistic corrections lead to large…
We investigate the production of a quark-antiquark pair in diffractive photon- proton scattering, approximating soft pomeron exchange by the exchange of two nonperturbative gluons. In deep inelastic scattering at HERA, events with two jets…
Charmonium sum rules for pseudoscalar 0^{-+} state eta_c(1S) are analyzed within perturbative QCD and Operator Product Expansion. The perturbative part of the pseudoscalar correlator is considered at alpha_s^2 order and the contribution of…
The total charm-quark production cross section per unit of rapidity $\mathrm{d}\sigma({\rm c\overline{c}})/\mathrm{d}y$, and the fragmentation fractions of charm quarks to different charm-hadron species $f(\mathrm{c}\rightarrow {\rm…
We use the covariant four-dimensional Bethe-Salpeter (BS) equation to determine the effective charm quark mass. The scale dependence of the effective charm quark mass is determined using experimentally known spin-one charmonium spectra and…
In this work, $T_{cc}$ double charm tetraquark and $1^{+}$ and $0^{+}$ hidden charm tetraquarks are studied within the QCD sum rules framework. In the heavy-quark limit, the $1^+$ and $0^+$ tetraquarks are degenerate and the difference in…
The observables epsilon_K and Delta M_K play a prominent role in particle physics due to their sensitivity to new physics at short distances. To take advantage of this potential, a firm theoretical prediction of the standard-model…
We present a new lattice QCD analysis of heavy-quark pseudoscalar-pseudoscalar correlators, using gluon configurations from the MILC collaboration that include vacuum polarization from $u$, $d$, $s$ and $c$~quarks($n_f=4$). We extract new…
Recent results on heavy flavor production at HERA are presented. New measurements of charm production are available in the region of $ Q^2 <$ 1000 GeV$^2$ for $D^*$ and in the photoproduction limit, $Q^2\to 0$, for $D_s$. The results are…
We present a new determination of the top-quark mass $m_t$ based on the experimental data from the Tevatron and the LHC for single-top hadro-production. We use the inclusive cross sections of $s$- and $t$-channel top-quark production to…
Recent CMS observations in the di-$J/\psi$ invariant mass spectrum reveal new structures at 6638 MeV ($X(6600)$)) and 7134 MeV, and confirm the $X(6900)$ at 6847 MeV. These findings provide crucial insights into four-charm-quark matter. The…
In this article, we assume that there exists a scalar hidden charm tetraquark state in the $\pi^+ \chi_{c1}$ invariant mass distribution, and study its mass using the QCD sum rules. The numerical result $M_{Z}=(4.36\pm0.18) \rm{GeV}$ is…
We review lattice determinations of the charm and bottom quark masses and the strong coupling constant obtained by different methods. We explain how effective field theory approaches, such as Non-Relativistic QCD (NRQCD), potential…
Heavy-light meson system is investigated using the relativistic heavy quark action on the 2+1 dynamical flavor PACS-CS configurations at the lattice spacing $a^{-1}=2.2$ GeV and the spatial extent L=3 fm. Dynamical up-down and strange quark…
Selected new results from the H1 and ZEUS collaborations on $ep$ interactions at 300 - 318 GeV centre-of-mass energy are presented. The full pre-upgrade integrated luminosity of HERA of 110 pb$^{-1}$ is used. Charm cross sections are…
A calculation of the next-to-leading order cross section for the inclusive hadroproduction of charm quarks including heavy quark mass effects in the hard scattering cross sections is presented. It is described how the massive hard…
We present an unbiased determination of the charm content of the proton, in which the charm parton distribution function (PDF) is parametrized on the same footing as the light quarks and the gluon in a global PDF analysis. This…
We use the hard (Lipatov) pomeron for the low-x gluon distribution and provide a compact formula for the ratio $R^{c} =F_{L}^{c}/F_{2}^{c}$ that is useful to extract the charm structure function from the reduced charm cross-section, in…
We study the expansion method for the gluon distribution function at low x values and calculate the charm structure functions in the LO and NLO analysis. Our results provide a compact formula for the ratio $R^{c} =F^{c}_{L}/F^{c}_{2}$,…
We outline the existing descriptions of the charm component of the deep inelastic proton structure function F2. We discuss recent approaches to include charm mass effects in the parton evolution equations and the coefficient functions.