Search

In this work, we evaluated the widths of the pionic and radiative transitions from the T c s ¯ 0 + (2900) to the D s 1 + (2460) in the D s 1 + (2460) molecular frame and the D s 1 + (2460) charmed-strange meson frame. Our estimations demonstrate that the transition widths in the D s 1 + (2460) molecular frame are much larger than those in the the D s 1 + (2460) charmed-strange meson frame. Specifically, the ratio of the widths of Γ (T c s ¯ 0 + (2900) → D s 1 + π 0) and Γ (T c s ¯ 0 + (2900) → D + (0) K 0 (+)) is estimated to be around 0.1 in the D s 1 + (2460) charmed-strange meson frame, whereas the lower limit of this ratio is 0.67 in the D s 1 + (2460) molecular frame. Thus, the aforementioned ratio could be employed as a tool for testing the nature of the D s 1 + (2460) . [ABSTRACT FROM AUTHOR]

We calculate the masses of χ c (3 P) states with threshold corrections in a coupled-channel model. The model was recently applied to the description of the properties of χ c (2 P) and χ b (3 P) multiplets (Ferretti and Santopinto in Phys Lett B 789:550, 2019]. We also compute the open-charm strong decay widths of the χ c (3 P) states and their radiative transitions. According to our predictions, the χ c (3 P) states should be dominated by the charmonium core, but they may also show small meson-meson components. The X(4274) is interpreted as a c c ¯ χ c 1 (3 P) state. More information on the other members of the χ c (3 P) multiplet, as well as a more rigorous analysis of the X(4274)'s decay modes, are needed to provide further indications on the quark structure of the previous resonance. [ABSTRACT FROM AUTHOR]

In this article, we calculate the $B_{c}^{*} \to B_{c}$ electromagnetic form-factor with the three-point QCD sum rules and then study the radiative decays $B_{c}^{*\pm} \to B_{c}^{\pm} \gamma$. Experimentally, we can study the radiative transitions using the decay cascades $B_{c}^{*\pm}\to B_{c}^{\pm} \gamma\to J/\psi\ell^{\pm}\bar{\nu}_{\ell} \gamma\to\mu^{+} \mu^{-} \ell^{\pm}\bar{\nu}_{\ell} \gamma$ in the future at the LHCb. [ABSTRACT FROM AUTHOR]

Radiative transitions between charmonium states offer an insight into the internal structure of heavy quark bound states within QCD. In this work, we systematically investigate the coupled-channel effects of intermediate charmed mesons to charmonium radiative transitions utilizing an effective Lagrangian approach. Our results show that the coupled-channel effects of these decays under the open charm thresholds are relatively weak, while the coupled-channel effects of the excited P-wave states close to the charmed pairs thresholds are relatively important. [ABSTRACT FROM AUTHOR]

We investigate the dependence of the chiral condensate $\langle\bar{q}q\rangle$ on the temperature and quark density using the soft-wall holographic model of QCD, adopting geometries with black holes at finite temperature and quark chemical potential μ. We find that, for μ below a critical value, increasing the temperature the condensate decreases and vanishes at a temperature $\tilde{T}\simeq210~\mathrm{MeV}$ (at μ=0). An analogous behaviour is observed increasing the chemical potential at fixed temperature. These results agree with the findings obtained by other methods. We also comment on the robustness of the results if geometries not involving black holes are adopted at low temperature, and an Hawking-Page transition is implemented. [ABSTRACT FROM AUTHOR]

We suggest a new CPX-derived scenario for the search for strangephilic MSSM Higgs bosons at the Tevatron and the LHC, in which all neutral and charged Higgs bosons decay predominantly into pairs of strange quarks and into a strange and a charm quark, respectively. The proposed scenario is realized within a particular region of the MSSM parameter space and requires large values of tan β, where threshold radiative corrections are significant to render the effective strange-quark Yukawa coupling dominant. Experimental searches for neutral Higgs bosons based on the identification of b-quark jets or τ leptons may miss a strangephilic Higgs boson and its existence could be inferred indirectly by searching for hadronically decaying charged Higgs bosons. Potential strategies and experimental challenges to search for strangephilic Higgs bosons at the Tevatron and the LHC are discussed. [ABSTRACT FROM AUTHOR]

By using a constituent quark model we compute the form factors relevant to semileptonic transitions of the B mesons into low-lying p-wave charmed mesons. We evaluate the q2 dependence of these form factors and compare them with other model calculations. The Isgur–Wise functions τ1/2 and τ3/2 are also obtained in the heavy quark limit of our results. [ABSTRACT FROM AUTHOR]

We focus on the chiral Lagrangian couplings describing radiative corrections to weak semi-leptonic decays and relate them to the decay amplitude of a lepton, computed by Braaten and Li at one loop in the standard model. For this purpose, we follow a two-step procedure. A first matching, from the standard model to Fermi theory, yields a relevant set of counterterms. The latter are related to chiral couplings thanks to a second matching, from Fermi theory to the chiral Lagrangian, which is performed using the spurion method. We show that the chiral couplings of physical relevance obey integral representations in a closed form, expressed in terms of QCD chiral correlators and vertex functions. We deduce exact relations among the couplings, as well as numerical estimates which go beyond the usual $\log(M_Z/M_\rho)$ approximation. [ABSTRACT FROM AUTHOR]

We focus on the chiral Lagrangian couplings describing radiative corrections to weak semi-leptonic decays and relate them to the decay amplitude of a lepton, computed by Braaten and Li at one loop in the standard model. For this purpose, we follow a two-step procedure. A first matching, from the standard model to Fermi theory, yields a relevant set of counterterms. The latter are related to chiral couplings thanks to a second matching, from Fermi theory to the chiral Lagrangian, which is performed using the spurion method. We show that the chiral couplings of physical relevance obey integral representations in a closed form, expressed in terms of QCD chiral correlators and vertex functions. We deduce exact relations among the couplings, as well as numerical estimates which go beyond the usual $\log(M_Z/M_\rho)$ approximation. [ABSTRACT FROM AUTHOR]

The computation of the radiation flux related to the Hawking temperature of a Schwarzschild black hole or another geometric background is still well-known to be fraught with a number of delicate problems. In spherical reduction, as shown by one of the present authors (Kummer) with Vassilevich, the correct black body radiation follows when two “basic components” (conformal anomaly and a “dilaton” anomaly) are used as input in the integrated energy-momentum conservation equation. The main new element in the present work is the use of a quite different method, the covariant perturbation theory of Barvinsky and Vilkovisky, to establish directly the full effective action which determines these basic components. In the derivation of Kummer and Vassilevich the computation of the dilaton anomaly implied one potentially doubtful intermediate step which can be avoided here. Moreover, the present approach also is sensitive to IR (renormalization) effects. We realize that the effective action naturally leads to expectation values in the Boulware vacuum which, making use of the conservation equation, suffice for the computation of the Hawking flux in other quantum states, in particular for the relevant Unruh state. Thus, a rather comprehensive discussion of the effects of (UVandIR) renormalization upon radiation flux and energy density is possible. [ABSTRACT FROM AUTHOR]

Radiative transitions between charmonium states offer an insight into the internal structure of heavy quark bound states within QCD. In this work, we performed a systematically investigation of the radiative transitions of ψ (n S) → γ χ cJ (m P) and ψ (n D) → γ χ cJ (m P) via intermediate charmed meson loop with a non-relativistic effective field theory. We only focus on the line-shape behavior of the distributions via different intermediate meson loops. Our results show that the coupled-channel effects of these decays are relatively weak, while the coupled channel effects has obvious enhancement when the inial (final) states are closed to the thresholds of charmed-mesons pair. [ABSTRACT FROM AUTHOR]

In this work, we study higher bottomonia up to the nL=8S, 6P, 5D, 4F, 3G multiplets using the modified Godfrey-Isgur (GI) model, which takes account of color screening effects. The calculated mass spectra of bottomonium states are in reasonable agreement with the present experimental data. Based on spectroscopy, partial widths of all allowed radiative transitions, annihilation decays, hadronic transitions, and open-bottom strong decays of each state are also evaluated by applying our numerical wave functions. Comparing our results with the former results, we point out difference among various models and derive new conclusions obtained in this paper. Notably, we find a significant difference between our model and the GI model when we study D, F, and G and n≥4 states. Our theoretical results are valuable to search for more bottomonia in experiments, such as LHCb, and forthcoming Belle II. [ABSTRACT FROM AUTHOR]