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We briefly comment on the paper by Albaladejo et al. [arXiv:1709.09101], rejecting its conclusions.
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The production of the X(3872) as a hadronic molecule in hadron colliders is clarified. We show that the conclusion of Bignamini et al., Phys. Rev. Lett. 103 (2009) 162001, that the production of the X(3872) at high $p_T$ implies a non-molecular structure, does not hold. In particular, using the well understood properties of the deuteron wave function as an example, we identify the relevant scales in the production process.
We evaluate the production cross sections of $X(3872)$ at the LHC and Tevatron at NLO in $alpha_s$ in NRQCD by assuming that the short-distance production proceeds dominantly through its $chi_{c1}$ component in our $chi_{c1}mbox{-}D^0bar{D}^{*0}$ mixing model for $X(3872)$. The outcomes of the fits to the CMS $p_T$ distribution can well account for the recent ATLAS data in a much larger range of transverse momenta ($10~mbox{GeV}<p_T<70~mbox{GeV}$), and the CDF total cross section data, and are also consistent with the value of $k=Z_{cbar c}cdot Br(Xto J/psipi^+pi^-)$ constrained by the $B$-meson decay data. %It can also well describe the behavior of the CDF $psi(2S)$ data, which show a strong %resemblance to that of the X(3872). For LHCb the predicted X(3872) total cross section is larger than the data by a factor of 2, which is due to the problem of the fixed-order NRQCD calculation that may not be applicable for the region with small $p_T$ ($p_Tsim 5 ~mbox{GeV}$) and large forward rapidity $(2.5<y<4.5)$. In comparison, the prediction of molecule production mechanism for $X(3872)$ is inconsistent with both $p_T$ distributions and total cross sections of CMS and ATLAS, and the total cross section of CDF.
We examine, as model-independently as possible, the production of bileptons at hadron colliders. When a particular model is necessary or useful, we choose the 3-3-1 model. We consider a variety of processes: q anti-q -> Y^{++} Y^{--}, u anti-d -> Y^{++} Y^{-}, anti-u d -> Y^+ Y^{--}, q anti-q -> Y^{++} e^{-} e^{-}, q anti-q -> phi^{++} phi^{--}, u anti-d -> -> phi^{++} phi^{-}, and anti-u d -> phi^{+} phi^{--}, where Y and phi are vector and scalar bileptons, respectively. Given the present low-energy constraints, we find that at the Tevatron, vector bileptons are unobservable, while light scalar bileptons (M_phi <= 300 GeV) are just barely observable. At the LHC, the reach is extended considerably: vector bileptons of mass M_Y <= 1 TeV are observable, as are scalar bileptons of mass M_phi <= 850 GeV.
We present theoretical results with soft-gluon corrections for two separate processes: (1) the production of a single top quark in association with a $W$ boson in the Standard Model; and (2) the production of a single top quark in association with a heavy $Z$ boson in new physics models with or without anomalous couplings. We show that the higher-order corrections from soft-gluon emission are dominant for a wide range of collider energies. Results are shown for the total cross sections and top-quark transverse-momentum and rapidity distributions for $tW$ and $tZ$ production at LHC and future collider energies up to 100 TeV. The uncertainties from scale dependence and parton distribution functions are also analyzed.
We present a method to compute off-shell effects for processes involving resonant particles at hadron colliders with the possibility to include realistic cuts on the decay products. The method is based on an effective theory approach to unstable particle production and, as an example, is applied to t-channel single top production at the LHC.
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