Hadronic production of the doubly heavy baryonΞbcat the LHC

Abstract

We investigate the hadronic production of the doubly heavy baryon Ξ bc at the large hadron collider (LHC), where contributions from the four (bc)-diquark states (bc)3 ,6 [ 1 S0] and (bc)3 ,6 [ 3 S1] have been taken into consideration. Numerical results show that under the condition of pT > 4 GeV and |y| < 1.5, sizable Ξ bc events about 1.7 × 10 7 and 3.5 × 10 9 per year can be produced for the center-of-mass energy √ S = 7 TeV and √ S = 14 TeV respectively. For experimental usage, the total and the interested differential cross-sections are estimated under some typical pT -and y-cuts for the LHC detectors CMS, ATLAS and LHCb. Main uncertainties are discussed and a comparative study on the hadronic production of Ξcc, Ξ bc and Ξ bb at LHC are also presented.

Implications of LHCb measurements and future prospects

“…These studies will require the statistics and improved triggering of the LHCb upgrade. Heavier states such as the Ω cc , Ξ bc , and Ξ bb have still smaller production cross-sections [585]. First studies towards Ξ bc detection are in progress.…”

“…The lightest of these, the Ξ cc isodoublet, have an estimated cross-section of O(10 2 ) nb [584,585] and so should be visible with 5 fb −1 collected with the current detector. However, the statistics may be marginal for follow-on analyses: measurements of the lifetime and ratios of branching fractions, searches for excited states, and so forth.…”

bcdiquark pair production in high energy proton-proton collisions

“…(20) are given in Table I. There is no such model available for sextuplet diquarks, so all their nonperturbative parameters, including R(0), are simply taken equal to the ones of triplet diquarks, what is the common practice allowing to roughly estimate the order of contributions from these color states [5,[22][23][24][25][26][27][28]. The relativistic parameters ω nk from Table I are almost indistinguishable for scalar and axial-vector (bc) diquarks, and this fact was used to slightly simplify the final view of the cross section (19).…”

“…Both octet and sextuplet cases require an additional gluon to be emitted in the nonperturbative part of the process, what generally O(v 2 ) suppresses the appropriate matrix elements, if the required emission is attributed to the heavy quark of relative velocity v. Nevertheless, in the case of double heavy baryon the final state also contains a light quark, which produces gluon easily, so that the different power counting rules can be applied, and both antitriplet and sextuplet matrix elements turn out to be of the same order [22]. Under this assumption, the sextuplet mechanism was shown to be equally or even more important than conventional antitriplet channel for various high energy processes of double heavy baryon production [22][23][24][25][26][27][28].…”

Spectroscopy of doubly-heavy baryons at LHCb

“…There is not expected to be one obvious discovery mode for these states so searches for them will be done as a multi-channel analysis. The cross-sections and branching fractions for these particles are also expected to be much smaller than that of doubly charmed baryons [13].…”