B_c excitations at LHC experiments

Abstract

The 2S B c states observed by ATLAS, CMS and LHCb Collaborations are discussed. The observation perspectives of B * c , 2P wave, 3P wave and D wave states of B c at LHC experiments are estimated. INTRODUCTIONB c -meson is a nonrelativistic two heavy quark system, and like (bb) and (cc) states can be considered in the potential model framework that predicts 19 bounded states (bc) below the decay threshold to BD (see [1][2][3][4]). Unlike (bb)or (cc)-quarkonium, there are no annihilation decay modes for these states, which makes the (bc) system similar to usual bq or cq-meson. The first observation of the ground state B c -meson was done at Tevatron collider (CDF and D0 experiments) in two decay modes: B c → Jψlν (l = e, µ) and B c → Jψπ [5-8]. Now this discovery is repeatedly confirmed by the LHC Collaborations LHCb, CMS, ATLAS in numeral decay modes: B c → Jψπ [9-11], B c → Jψπππ [10, 12], B c → J/ψlν [13], B c → J/ψK [14], B c → ψ(2S)π [15], B c → J/ψπKK [16], B c → JψD ( * ) K ( * ) [17, 18], B c → J/ψD ( * ) s [19, 20], B c → J/ψπpp [21], B c → J/ψ3π + 2π − [22] and B c → B s π + [23]. It is worth to note that most of these decays occur due to transformation b → cW . The only observed mode with c quark decay is B c → B s π + . The annihilation channel is not observed yet. It is interesting to note that according to theoretical predictions the dominant decay channel is c → sW , the contribution of b → cW is smaller, and the smallest contribution is *

Photonic production of a pair of Bc mesons

“…The B c meson is the bound state of two heavy quark and anti-quark ðb; cÞ or ðb;cÞ. At present, the ground state B c ð0 − Þ with the mass M B c ¼ 6274.9 AE 0.8 MeV [22] and two excited states B c ð2 1 S 0 Þ þ with mass 6872.1 AE 1.3ðstatÞ AE 0.1ðsystÞ AE 0.8ðB þ c Þ MeV and B c ð2 3 S 1 Þ þ with mass 6841.2 AE 0.6ðstatÞ AE 0.1ðsystÞ AE 0.8ðB þ c Þ MeV have been discovered [22][23][24]. A new precision measurement of the B þ c meson mass is performed using proton-proton collision data collected with the LHCb experiment in [25].…”

Bc excitations at LHC: first observations and further research prospects

“…The peaks are plotted with respect to rough model of detector resolution: broadening the source histograms with Gaussian function with dispersion of 6 MeV. It should be stressed that such simulation is just an estimation and doesn't reflect the actual properties of detector (see also [32] and [33]).…”

“…That is why in study [28] we discussed the other B c excitations, namely, 2S -wave states and P-wave states, and these states are more preferable for observation. The recent observation of 2S states in ATLAS [29], CMS [30] and LHCb [31] made us return to this discussion (see also [32] and [33]).…”

The light invisible boson in FCNC decays of B and $$B_c$$ mesons

“…While previous studies most focus on B meson instead of B c meson. The B c meson has been massively produced and measured by the CDF [28], ATLAS [29], CMS [30], and LHCb [31] experiments. The production rate of B c meson on the LHCb collaboration is close to 3.7 per mille of that of the B mesons [31].…”