The Effect of Higher Dimensional QCD Operators on the Spectroscopy of Bottom-Up Holographic Models

Within the bottom-up holographic approach to QCD, the highly excited hadrons are identified with the bulk normal modes in the fifth “holographic” dimension. We show that additional states in the same mass range can appear also from taking into consideration the 5D fields dual to higher dimensional QCD operators. The possible effects of these operators have not been taken into account in virtually any phenomenological applications. Using the scalar case as the simplest example, we demonstrate that the additional higher dimensional operators lead to a large degeneracy of highly excited states in the soft wall holographic model, and in the hard wall holographic model, they result in a proliferation of excited states. The considered model can be viewed as the first analytical toy model predicting a one-to-one mapping of the excited meson states to definite QCD operators, to which they prefer to couple.

Measurement of CP observables in B± → D(*)K± and B± → D(*)π± decays using two-body D final states

Measurements of CP observables in B± → D(*)K± and B± → D(*)π± decays are presented, where D(∗) indicates a neutral D or D∗ meson that is an admixture of meson and anti-meson states. Decays of the D(∗) meson to the Dπ0 and Dγ final states are partially reconstructed without inclusion of the neutral pion or photon. Decays of the D meson are reconstructed in the K±π∓, K+K−, and π+π− final states. The analysis uses a sample of charged B mesons produced in proton-proton collisions and collected with the LHCb experiment, corresponding to integrated luminosities of 2.0, 1.0, and 5.7 fb−1 taken at centre-of-mass energies of 7, 8, and 13 TeV, respectively. The measurements of partially reconstructed B± → D(*)K± and B± → D(∗)π± with D → K∓π± decays are the first of their kind, and a first observation of the B± → $$ {\left(D{\pi}^0\right)}_{D^{\ast }}{\pi}^{\pm } $$ D π 0 D ∗ π ± decay is made with a significance of 6.1 standard deviations. All CP observables are measured with world-best precision, and in combination with other LHCb results will provide strong constraints on the CKM angle γ.

Nonrelativistic treatment of fully-heavy tetraquarks as diquark-antidiquark states

The goal of the present work is to obtain a reliable estimate of the masses of the ground and radially excited states of fully-heavy tetraquark systems. In order to do this, we use a nonrelativistic model of tetraquarks which are assumed to be compact and consist of diquark-antidiquark pairs. This nonrelativistic model is composed of Hulthen potential, a linear confining potential and spin-spin interaction. We computed ground, first, and second radially excited $$cc{\bar{c}}{\bar{c}}$$ c c c ¯ c ¯ and $$bb{\bar{b}}{\bar{b}}$$ b b b ¯ b ¯ tetraquark masses. It was found that predicted masses of ground states of $$cc{\bar{c}}{\bar{c}}$$ c c c ¯ c ¯ and $$bb{\bar{b}}{\bar{b}}$$ b b b ¯ b ¯ tetraquarks are significantly higher than the thresholds of the fall-apart decays to the lowest allowed two-meson states. These states should be broad and are thus difficult to observe experimentally. First radially excited states are considerably lower than their corresponding (2S-2S) two-meson thresholds. We hope that our study may be helpful to the experimental search for ground and excited $$cc{\bar{c}}{\bar{c}}$$ c c c ¯ c ¯ and $$bb{\bar{b}}{\bar{b}}$$ b b b ¯ b ¯ tetraquark states.

Coupling Hadron-Hadron Thresholds within a Chiral Quark Model Approach

Heavy hadron spectroscopy was well understood within the naive quark model until the end of the past century. However, in 2003, the X(3872) was discovered, with puzzling properties difficult to understand in the simple naive quark model picture. This state made clear that excited states of heavy mesons should be coupled to two-meson states in order to understand not only the masses but, in some cases, unexpected decay properties. In this work, we will give an overview of a way in which the naive quark model can be complemented with the coupling to two hadron thresholds. This program has been already applied to the heavy meson spectrum with the chiral quark model, and we show some examples where thresholds are of special relevance.

Strong decays of the lowest bottomonium hybrid within an extended Born–Oppenheimer framework

We analyze the decays of the theoretically predicted lowest bottomonium hybrid H(1P) to open bottom two-meson states. We do it by embedding a quark pair creation model into the Born–Oppenheimer framework which allows for a unified, QCD-motivated description of bottomonium hybrids as well as bottomonium. A new $$^{1}\!P_{1}$$ 1 P 1 decay model for H(1P) comes out. The same analysis applied to bottomonium leads naturally to the well-known $$^{3}\!P_{0}$$ 3 P 0 decay model. We show that H(1P) and the theoretically predicted bottomonium state $$\varUpsilon (5S)$$ Υ ( 5 S ) , whose calculated masses are close to each other, have very different widths for such decays. A comparison with data from $$\varUpsilon (10860)$$ Υ ( 10860 ) , an experimental resonance whose mass is similar to that of $$\varUpsilon (5S)$$ Υ ( 5 S ) and H(1P), is carried out. Neither a $$\varUpsilon (5S)$$ Υ ( 5 S ) nor a H(1P) assignment can explain the measured decay widths. However, a $$\varUpsilon (5S)$$ Υ ( 5 S ) –H(1P) mixing may give account of them supporting previous analyses of dipion decays of $$\varUpsilon (10860)$$ Υ ( 10860 ) and suggesting a possible experimental evidence of H(1P).

Charged Higgs contribution on Bc → (Ds, Ds*) l+l−

In this paper, we study rare semileptonic decays of the $B_c$ meson in the context of type-I, II, and III two Higgs doublet models. We follow the relativistic quark model for parameterizing the form factors used in matrix elements of weak transitions between the corresponding meson states. We investigate observables such as branching ratio, lepton polarization asymmetry, forward–backward asymmetry, etc. and analyze the dependence of these quantities on the model parameters. We have found that there is noticeable sensitivity to these observables for the charged Higgs boson, which may provide a powerful probe to the standard model and new physics beyond it.

Review of Charmonium and Bottomonium Quark State Production via Relativistic Heavy Ion Collisions

This is a review of the production of heavy quark states via relativistic heavy ion collisions in RHIC. The heavy quarks here are c, charm quark, and b, bottom quark. The states are charmonium meson states Ψ ( n S ) , with n = 1,2 and upsilon meson states Υ ( m S ) , with m = 1,2,3. Quantum Chromodynamics (QCD) sum rules were used to derive the result that the Ψ ( 2 S ) and Υ ( 3 S ) are mixed hybrid states, which increase their production cross sections. We also review the Ψ ( n S ) and Υ ( m S ) production cross sections via Cu-Cu and Au-Au collisions, which are very important for this review of the production of heavy quark states in RHIC. The possible detection of the Quark Gluon Plasma (QGP) is also reviewed.

Up-down asymmetries of charmed baryon three-body decays

We study the up-down asymmetries in the three-body anti-triplet charmed baryon decays of $$\mathbf{B}_{\mathbf{c}}\rightarrow \mathbf{B}_{\mathbf{n}}MM' $$Bc→BnMM′ with the $$SU(3)_f$$SU(3)f flavor symmetry, where $$\mathbf{B}_{\mathbf{c}}$$Bc presents the anti-triplet charmed baryon of $$(\Xi _c^0,-\Xi _c^+,\Lambda _c^+)$$(Ξc0,-Ξc+,Λc+), while $$\mathbf{B}_{\mathbf{n}}$$Bn and $$M^{(')}$$M(′) denote octet baryon and meson states, respectively. By assuming the s-wave meson-pairs to be the dominant constituents in final state configurations, we can write the spin-dependent decay amplitude into parity-conserving and parity-violating parts, parametrized by 6 real parameters under $$SU(3)_f$$SU(3)f, respectively. Fitting these parameters by 16 experimental data points with the minimum $$\chi ^2$$χ2 method, we obtain that $$\chi ^2/d.o.f=2.4$$χ2/d.o.f=2.4. With the fitted parameters, we evaluate the up-down asymmetries along with the decay branching ratios of $$\mathbf{B}_{\mathbf{c}}\rightarrow \mathbf{B}_{\mathbf{n}}MM' $$Bc→BnMM′. Some of these up-down asymmetries are accessible to the experiments at BESIII, BELLE-II and LHCb.