In experiments, only one doubly charmed baryon $$\Xi _{cc}^{++}$$ has been successfully identified to date. The LHCb collaboration is poised to discover other doubly heavy baryons, $$\Xi _{cc}^{+}$$ and $$\Xi _{bc}^{+}$$ , necessitating a comprehensive study of doubly heavy baryons from various perspectives. Such investigations will elucidate the properties of the newly discovered states and facilitate the search for other doubly heavy baryons as predicted in the quark model. In this paper, we explore the strong coupling between the doubly heavy baryon, singly heavy baryon, and heavy meson, $$\mathcal{B}_{QQ^{\prime }}\mathcal{B}_{Q}M_{Q^{\prime }}$$ , using the light-cone QCD sum rules approach. We analytically and numerically calculate the strong coupling, $$\mathcal{B}_{QQ^{\prime }}\mathcal{B}_{Q}M_{Q^{\prime }}$$ , utilizing the light-cone distribution amplitudes of the singly heavy baryon $$\mathcal{B}_{Q}$$ . Numerical predictions for these strong couplings are provided, along with an error analysis. Our theoretical findings can be employed to examine the strong and weak decay dynamics of doubly heavy baryons. Furthermore, our results may offer experimentalists a valuable tool for analyzing data on the strong coupling constants among hadronic multiplets.

China

Xiao-Hui Hu

Quan-Yu Zhou

Ye Xing

Yu-Ji Shi

The strong coupling constants of doubly heavy baryons with heavy mesons

In this work, gravitational lensing in the weak and strong field limits is investigated for black hole spacetime within the framework of Hu–Sawicki ( ) gravity. We employ the Ishihara et al. approach for weak lensing and adopt Bozza’s method for strong lensing to explore the impact of Hu–Sawicki model parameters on lensing phenomenon. The deflection angles are computed and analyzed in both the field limits. Our investigation in the weak as well as the strong lensing reveals that in the case of Hu–Sawicki black holes, photons exhibit divergence at smaller impact parameters for different values of the model parameters compared to the Schwarzschild scenario and the photon experiences negative deflection angle when impact parameter moves towards the larger impact parameter values. Additionally, by calculating strong lensing coefficients we study their behavior with model parameters. The strong lensing key observables associated with the lensing effect viz. the angular position $$\vartheta _{\infty }$$ , angular separation and relative magnification $$r_\text {mag}$$ are estimated numerically by extending the analysis to supermassive black holes $$\text {SgrA}^*$$ and $$\text {M87}^*$$ and analyzed their behavior concerning the parameters for each black hole. The analysis shows that $$\text {SgrA}^*$$ demonstrates larger values of $$\vartheta _{\infty }$$ and relative to $$\text {M87}^*$$ .

India

Gayatri Mohan

Nashiba Parbin

Umananda Goswami

Investigating the effects of gravitational lensing by Hu-Sawicki $$\varvec{f(R)}$$ gravity black holes

<p>The doubly charmed baryon, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Ξ</mi><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo><mo>+</mo></mrow></msubsup></math>, was first observed by LHCb through the nonleptonic decay modes of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo><mo>+</mo></mrow></msubsup><mo stretchy="false">→</mo><msubsup><mrow><mi mathvariant="normal">Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><msup><mrow><mi>K</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Ξ</mi><mi>c</mi><mo>+</mo></msubsup><msup><mi>π</mi><mo>+</mo></msup></math>. Following this discovery, researchers shifted their focus to identifying other doubly charmed baryons, specifically <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Ξ</mi><mrow><mi>c</mi><mi>c</mi></mrow><mo>+</mo></msubsup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Ω</mi><mrow><mi>c</mi><mi>c</mi></mrow><mo>+</mo></msubsup></math>. In this study, we examine the nonleptonic weak decays of doubly charmed baryons, denoted as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">B</mi><mrow><mi>c</mi><mi>c</mi></mrow></msub><mo stretchy="false">→</mo><msub><mi mathvariant="script">B</mi><mi>c</mi></msub><mi>P</mi></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">B</mi><mrow><mi>c</mi><mi>c</mi></mrow></msub></math> represents the doubly charmed baryons, specifically <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><msubsup><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo><mo>+</mo></mrow></msubsup><mo>,</mo><msubsup><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo>,</mo><msubsup><mrow><mi mathvariant="normal">Ω</mi></mrow><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo stretchy="false">)</mo></mrow></math>. The notation <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">B</mi><mi>c</mi></msub></math> denotes the singly charmed baryons, specifically <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><msub><mi mathvariant="script">B</mi><mover accent="true"><mn>3</mn><mo stretchy="false">¯</mo></mover></msub><mo>,</mo><msub><mi mathvariant="script">B</mi><mn>6</mn></msub><mo stretchy="false">)</mo></math>, while <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>P</mi></math> signifies the light pseudoscalar. These terms are pertinent to the nonleptonic decay modes under discussion. While the short-distance contributions can be precisely estimated through theoretical calculations, addressing the long-distance contributions for final-state-interaction effects presents a significant challenge. In order to address this issue, we utilize the rescattering mechanism of final state interaction effects to compute the long-distance contributions. We initially derive the entire hadronic loop contributions for these two-body nonleptonic decays of doubly charmed baryons. In subsequent analyses, we are able to calculate relative strong phases. As a result, we can provide predictions for their decay asymmetry parameters and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>C</mi><mi>P</mi></mrow></math> violations. Furthermore, we employ experimental data from the LHCb collaboration, specifically the ratio <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>Br</mi><mo stretchy="false">(</mo><msubsup><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo><mo>+</mo></mrow></msubsup><mo stretchy="false">→</mo><msubsup><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>′</mo><mo>+</mo></mrow></msubsup><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">)</mo><mo>/</mo><mi>Br</mi><mo stretchy="false">(</mo><msubsup><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo><mo>+</mo></mrow></msubsup><mo stretchy="false">→</mo><msubsup><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>1.41</mn><mo>±</mo><mn>0.17</mn><mo>±</mo><mn>0.10</mn><mo stretchy="false">)</mo></mrow></math>, to ascertain the model parameters <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mo>=</mo><mn>0.9</mn><mo>±</mo><mn>0.2</mn></math>. Consequently, we present the predictions of branching ratios and decay asymmetry parameters for 67 distinct decay processes and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violations for the singly Cabibbo suppressed channels. This not only strengthens the validity of our theoretical predictions, but also provides a more comprehensive theoretical framework for the future identification of other doubly charmed baryons.</p>

Cai-Ping Jia

Fu-Sheng Yu

Final-state rescattering mechanism of double-charm baryon decays: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="script">B</mi></mrow><mrow><mi>c</mi><mi>c</mi></mrow></msub><mo stretchy="false">→</mo><msub><mrow><mi mathvariant="script">B</mi></mrow><mrow><mi>c</mi></mrow></msub><mi>P</mi></mrow></math>

We study the propagation of massless fermionic fields, implementing a family of special functions: Heun functions, in solving the wave equation in three three-dimensional backgrounds, including the BTZ black hole in string theory and Lifshitz black hole solutions in conformal gravity and Hu–Sawicki ( ) theory. The main properties of the selected black hole solutions is that their line elements are Weyl related to that of a homogeneous spacetime, whose spatial part possesses Lie symmetry, described by Lobachevsky-type geometry with arbitrary negative Gaussian curvature. Using the Weyl symmetry of massless Dirac action, we consider the perturbation equations of fermionic fields in relation to those of the homogeneous background, which having definite singularities, are transformed into Heun’s equation. We point out the existence of quasinormal modes labeled by the accessory parameter of the Heun function. The distribution of the quasinormal modes has been clarified to satisfy the boundary conditions that require ingoing and decaying waves at the event horizon and conformal infinity, respectively. It turned out that the procedure based on the Heun function, beside reproducing the previously known results obtained via hypergeometric function for the BTZ and Lifshitz black hole solution in conformal gravity, brings up new families of quasinormal frequencies, which can also contain purely imaginary modes. Also, the analysis of the quasinormal modes shows that with the negative imaginary part of complex frequencies $$\omega =\omega _{Re}+i\omega _{Im}$$ , the fermionic perturbations are stable in this background.

Iran

F. Naderi

A. Rezaei-Aghdam

Quasinormal modes of three $$(2+1)$$ -dimensional black holes in string theory, conformal gravity, and Hu–Sawicki

The b-factories, such as BelleII, BarBar, and LHCb, emphasize the increasing importance of exotic hadron research. In this paper, we discuss the possible production of singly anti-charmed pentaquark states   $\bar{c}q qqq$   from B mesons in a b-factory under   $\bar{c}q qqq$  (3) symmetry analysis. Discussions of both possibilities have been driven by the hypothesis that the pentaquark state considered in this work, known as the lowest lying state   $\bar{c}q qqq$  , could be bound or unbound. We find the golden channels for the production of the pentaquark ground states, such as   $\bar{c}q qqq$  . We further estimate the branching ratios for the production of the ground states   $\bar{c}q qqq$   from B meson decays. Thus, multiple channels are available for experiments, which may remove certain obstacles to the discovery of new pentaquark states.

Study of singly anti-charmed pentaquark production in -factory  

We derive novel black hole solutions in a modified gravity theory, namely the Hu–Sawicki model of f(R) gravity. After obtaining the black hole solution, we study the horizon radius of the black hole from the metric and then analyse the dependence of the model parameters on the horizon. We then use the 6th order WKB method to study the quasinormal modes of oscillations (QNMs) of the black hole perturbed by a scalar field. The dependence of the amplitude and damping part of the QNMs are analysed with respect to variations in model parameters and the error associated with the QNMs are also computed. After that we study some thermodynamic properties associated with the black hole such as its thermodynamic temperature as well as greybody factors. It is found that the black hole has the possibility of showcasing negative temperatures and is thermodynamically unstable for feasible values of model parameters. Then we analyse the geodesics and derive the photon sphere radius as well as the shadow radius of the black hole. The photon radius is independent of the model parameters while shadow radius showed fair amount of dependence on the model parameters. We tried to constrain the parameters with the help of Keck and VLTI observational data and obtained some bounds on m and  $$c_{2}$$  <math> <msub> <mi>c</mi> <mn>2</mn> </msub> </math>   parameters.

Ronit Karmakar

Quasinormal modes, thermodynamics and shadow of black holes in Hu–Sawicki  $$\varvec{f(R)}$$  <math> <mrow> <mi>f</mi> <mo>(</mo> <mi>R</mi> <mo>)</mo> </mrow> </math>   gravity theory

In this work, a three-quark picture is constructed using a bottom-up approach for baryons in a light-front quark model. The shape parameters, which characterize the momentum distribution inside a baryon, are determined with the help of the pole residue of the baryon. The relation between the three-quark picture and the diquark picture is clarified. When building the model, we find that Lorentz boost plays a crucial role, and the bottom-up modeling approach can be generalized to multiquark states. Based on this, a unified theoretical framework for describing multiquark states may be established. As a by-product of model construction, we can easily obtain a newly improved definition of baryon interpolating current. The hadron interpolating currents are the starting point of lattice QCD and QCD sum rules, and therefore are of great importance.

Zhen-Xing Zhao

Fu-Wei Zhang

Baryons in the light-front approach: The three-quark picture

In this work, we investigate the semileptonic weak decays of spin-<math><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></math> doubly heavy baryons <math><msub><mi>Ξ</mi><mrow><mi>Q</mi><msup><mi>Q</mi><mo>′</mo></msup></mrow></msub></math> into spin-<math><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></math> singly heavy baryons <math><msubsup><mi>Σ</mi><msup><mi>Q</mi><mo>′</mo></msup><mo>*</mo></msubsup></math> within light-cone sum rules. Using the parallel components of the light-cone distribution amplitudes of <math><msubsup><mi>Σ</mi><msup><mi>Q</mi><mo>′</mo></msup><mo>*</mo></msubsup></math>, the transition form factors for these decays are calculated both analytically and numerically. The numerical results for these semileptonic weak decays widths and branching ratios are also predicted, which are compared with the same predictions by other theoretical approaches in the literatures. These phenomenology predictions can be tested by the experiments in the future.

Germany

Light-cone sum rules analysis of <math><msub><mi>Ξ</mi><mrow><mi>Q</mi><msup><mi>Q</mi><mo>′</mo></msup><mi>q</mi></mrow></msub><mo>→</mo><msubsup><mi>Σ</mi><msup><mi>Q</mi><mo>′</mo></msup><mo>*</mo></msubsup></math> weak decays

We use the spectral lag catalog of 46 short GRBs aggregated by Xiao et al. (Astrophys J Lett 924:L29, 2022), to carry out an independent search for Lorentz invariance violation (LIV). For this purpose, we use a power-law model as a function of energy for the intrinsic astrophysical induced spectral lags. The expansion history of the universe needed for constraining LIV was obtained in a non-parametric method using cosmic chronometers. We use Bayesian model comparison to determine if the aforementioned spectral lags show evidence for LIV as compared to only astrophysically induced lags. We do not find any evidence for LIV, and obtain 95% CL lower limits on the corresponding energy scale to be  $$4 \times 10^{15}$$  <math> <mrow> <mn>4</mn> <mo>×</mo> <msup> <mn>10</mn> <mn>15</mn> </msup> </mrow> </math>   GeV and  $$6.8 \times 10^{9}$$  <math> <mrow> <mn>6.8</mn> <mo>×</mo> <msup> <mn>10</mn> <mn>9</mn> </msup> </mrow> </math>   GeV for the linear and quadratic LIV models respectively. Our results obtained by using the flat  $$\Lambda $$  <math> <mi>Λ</mi> </math>  CDM model for characterizing the cosmic expansion history are consistent with those obtained using chronometers.

Shantanu Desai

Rajdeep Agrawal

Haveesh Singirikonda

Search for Lorentz invariance violation using Bayesian model comparison applied to Xiao et al. GRB spectral lag catalog

As a continuation of our previous work, we investigate the weak decays of doubly-heavy baryons $$\Xi _{QQ^{\prime }}$$ <math><msub><mi>Ξ</mi><mrow><mi>Q</mi><msup><mi>Q</mi><mo>′</mo></msup></mrow></msub></math>  into sextet $$\Sigma _{Q^{\prime }}$$ <math><msub><mi>Σ</mi><msup><mi>Q</mi><mo>′</mo></msup></msub></math>  with light-cone sum rules. We calculate the form factors for these decays with the parallel light-cone distribution amplitudes of $$\Sigma _{Q^{\prime }}$$ <math><msub><mi>Σ</mi><msup><mi>Q</mi><mo>′</mo></msup></msub></math> . Numerical results of these form factors are used to predict the decay widths and branching ratios of the corresponding semi-leptonic processes. Parametric uncertainties and theoretical analyses are also given in detail. We find that the decay widths of $$\Xi _{cc}$$ <math><msub><mi>Ξ</mi><mrow><mi>cc</mi></mrow></msub></math>  and $$\Xi _{bc}$$ <math><msub><mi>Ξ</mi><mrow><mi>bc</mi></mrow></msub></math>  decays are several orders of magnitude larger than those of $$\Xi _{bb}$$ <math><msub><mi>Ξ</mi><mrow><mi>bb</mi></mrow></msub></math>  decays.

Light-cone sum rules analysis of $$\Xi _{QQ^{\prime }}\rightarrow \Sigma _{Q^{\prime }}$$ <math><mrow><msub><mi>Ξ</mi><mrow><mi>Q</mi><msup><mi>Q</mi><mo>′</mo></msup></mrow></msub><mo>→</mo><msub><mi>Σ</mi><msup><mi>Q</mi><mo>′</mo></msup></msub></mrow></math>  weak decays