The Effects of Charged Charm Mesons on the Line Shapes of the X(3872)

The quantum numbers J^PC = 1++ of the X(3872) and the proximity of its mass to the D*0 anti-D0 threshold imply that it is either a loosely-bound hadronic molecule whose constituents are a superposition of D*0 anti-D0 and D0 anti-D*0 or it is a virtual state of charm mesons. The line shapes of the X(3872) can discriminate between these two possibilities. At energies within a few MeV of the D*0 anti-D0 threshold, the lines shapes of the X produced in B -> K transitions are determined by its binding energy and its width. Their normalizations are determined by a short-distance constant that is different for B+ -> K+ and B0 -> K0. At energies comparable to the 8 MeV splitting between the D*0 anti-D0 and D*+ D- thresholds, the charged meson channels D*+ D- and D+ D*- have a significant effect on the line shapes of the X. We calculate the line shapes taking into account the resonant coupling between the charged and neutral 1++ channels. The line shapes and their normalizations depend on one additional scattering parameter and two additional short-distance constants associated with the B -> K transitions. The line shapes of the X resonance depend on its decay channel; they are different for J/psi pi+ pi-, J/psi pi+ pi- pi0, and D0 anti-D0 pi0. The line shapes are also different for X produced in B+ decays and in B0 decays. Some conceptual errors in previous work on this problem are pointed out.Comment: 30 pages, 7 figure

A smartphone-based device for measuring soil organic matter

The project evaluated the potential of utilizing a smartphone-based system for the in-field analysis of Soil Organic Matter. Although it demonstrated that the performance of the smartphone-based spectrometer can be comparable to commercial spectrometers, the results suggest that it is challenging to identify the spectral “signatures” of the SOM due to the morphology and moisture variation of soil samples

Weakly-bound Hadronic Molecule near a 3-body Threshold

The X(3872) seems to be a loosely-bound hadronic molecule whose constituents are two charm mesons. A novel feature of this molecule is that the mass difference of the constituents is close to the mass of a lighter meson that can be exchanged between them, namely the pion. We analyze this feature in a simple model with spin-0 mesons only. Various observables are calculated to next-to-leading order in the interaction strength of the exchanged meson. Renormalization requires summing a geometric series of next-to-leading order corrections. The dependence of observables on the ultraviolet cutoff can be removed by renormalizations of the mass of the heaviest meson, the coupling constant for the contact interaction between the heavy mesons, and short-distance coefficients in the operator product expansion. The next-to-leading order correction has an unphysical infrared divergence at the threshold of the two heavier mesons that can be eliminated by a further resummation that takes into account the nonzero width of the heaviest meson.Comment: 37 pages, 13 figures, submitted to Phys.Rev.

Deuteron-like states composed of two doubly charmed baryons

We present a systematic investigation of the possible molecular states composed of a pair of doubly charmed baryons ($\Xi_{cc}\Xi_{cc}$) or one doubly charmed baryon and one doubly charmed antibaryon $(\Xi_{cc}\bar{\Xi}_{cc})$ within the framework of the one-boson-exchange-potential model. For the spin-triplet systems, we take into account the mixing between the ${}^3S_1$ and ${}^3D_1$ channels. For the baryon-baryon system $\Xi_{cc}\Xi_{cc}$ with $(R,I) = (\bar{3}, 1/2)$ and $(\bar{3}, 0)$, where $R$ and $I$ represent the group representation and the isospin of the system, respectively, there exist loosely bound molecular states. For the baryon-antibaryon system $\Xi_{cc}\bar{\Xi}_{cc}$ with $(R,I) = (8, 1)$, $(8, 1/2)$ and $(8,0)$, there also exist deuteron-like molecules. The $B_{cc}\bar{B}_{cc}$ molecular states may be produced at LHC. The proximity of their masses to the threshold of two doubly charmed baryons provides a clean clue to identify them.Comment: 18 pages, 8 figure

Possible hadronic molecules composed of the doubly charmed baryon and nucleon

We perform a systematical investigation of the possible deuteron-like bound states with configuration $\Xi_{cc}N (\bar{N})$, where $N(\bar{N})$ denotes the nucleon (anti-nucleon), in the framework of the one-boson-exchange-potential model. In the spin-triplet sector we take into account both the ${}^3S_1$ and ${}^3D_1$ channels due to non-vanishing tensor force. There exist several candidates of the loosely bound molecular states for the $\Xi_{cc}N$ and $\Xi_{cc}\bar{N}$ systems, which lie below the threshold of $\Lambda_c\Lambda_c$ or $\Lambda_c{\bar\Lambda}_c$. We also investigate the possible loosely bound states with configurations $\Lambda_cN(\bar{N})$ and $\Sigma_cN(\bar{N})$. These molecular candidates may be searched for at Belle II and LHC in the near future.Comment: 14 pages, 5 figure