Chinese Physics C

Phase transition of non-linear charged Anti-de Sitter black holes

Yun-Zhi Du, Huai-Fan Li, Fang Liu, Ren Zhao, Li-Chun Zhang

2021, 45(11): 112001. doi: 10.1088/1674-1137/ac2049

HTML

PDF

Abstract:
Understanding the thermodynamic phase transition of black holes can provide a deep insight into the fundamental properties of black hole gravity to establish the theory of quantum gravity. We investigate the condition and latent heat of phase transition for non-linear charged AdS black holes using Maxwell's equal-area law. In addition, we analyze the boundary and curve of the two-phase coexistence area in the expanded phase space. We suggest that the phase transition of the non-linear charged AdS black hole with the fixed temperature (

\begin{document}$ T<T_{\rm c} $\end{document}

) is related to the electric potential at the horizon, not only to the location of black hole horizon. Recently, the molecular number density was introduced to study the phase transition and microstructure of black holes. On this basis, we discuss the continuous phase transition of a non-linear charged AdS black hole to reveal the potential microstructure of a black hole by introducing the order parameter and using the scalar curvature.

Chromomagnetic and chromoelectric dipole moments of quarks in the reduced 331 model

A. I. Hernández-Juárez, G. Tavares-Velasco, A. Moyotl

2021, 45(11): 113101. doi: 10.1088/1674-1137/ac1b9a

HTML

PDF

Abstract:
The one-loop contributions to the chromomagnetic dipole moment

\begin{document}$\hat\mu_t(q^2)$\end{document}

and electric dipole moment

\begin{document}$\hat d_t(q^2)$\end{document}

of the top quark are calculated within the reduced 331 model (RM331) for non-zero

\begin{document}$q^2$\end{document}

. It is argued that the results are gauge independent and thus represent valid observable quantities. In the RM331,

\begin{document}$\hat \mu_t(q^2)$\end{document}

receives new contributions from two heavy gauge bosons, namely

\begin{document}$Z'$\end{document}

and

\begin{document}$V^\pm$\end{document}

, and one neutral scalar boson

\begin{document}$h_2$\end{document}

, along with a new contribution from the standard model's Higgs boson via flavor changing neutral currents. The latter, which is also mediated by the

\begin{document}$Z'$\end{document}

gauge boson and the scalar boson

\begin{document}$h_2$\end{document}

, can provide a non-vanishing

\begin{document}$\hat d_t(q^2)$\end{document}

if there is a

\begin{document}$CP$\end{document}

-violating phase. The analytical results are presented in terms of both Feynman parameter integrals and Passarino-Veltman scalar functions, which are useful to cross-check the numerical results. Both

\begin{document}$\hat\mu_t(q^2)$\end{document}

and

\begin{document}$\hat d_t(q^2)$\end{document}

are numerically evaluated for parameter values still allowed by the constraints from experimental data. It is found that the new one-loop contributions of the RM331 to the real (imaginary) part of

\begin{document}$\hat \mu_t(q^2)$\end{document}

are of the order of

\begin{document}$10^{-5}$\end{document}

(

\begin{document}$10^{-6}$\end{document}

), which means at least three orders of magnitude smaller than the standard model prediction but larger than the predictions of other models of new physics. In the RM331, the dominant contribution arises from the

\begin{document}$V^\pm$\end{document}

gauge boson for

\begin{document}$\|q\|$\end{document}

in the 30-1000 GeV interval and a mass

\begin{document}$m_{V}$\end{document}

of the order of a few hundreds of GeV. As for

\begin{document}$\hat d_t(q^2)$\end{document}

, it receives its largest contribution from

\begin{document}$h_2$\end{document}

exchange and can reach values of the order of

\begin{document}$10^{-19}$\end{document}

, i.e., smaller than the contributions predicted by other standard model extensions.

Reanalysis of the top-quark pair hadroproduction and a precise determination of the top-quark pole mass at the LHC

Sheng-Quan Wang, Xing-Gang Wu, Jian-Ming Shen, Stanley J. Brodsky

2021, 45(11): 113102. doi: 10.1088/1674-1137/ac1bfd

HTML

PDF

Abstract:
In this study, we calculate the

\begin{document}$t\bar{t}$\end{document}

pQCD production cross-section at the NNLO and determine the top-quark pole mass from recent measurements at the LHC at the center-of-mass energy

\begin{document}$\sqrt{S}=13$\end{document}

TeV to a high precision by applying the principle of maximum conformality (PMC). The PMC provides a systematic method that rigorously eliminates QCD renormalization scale ambiguities by summing the nonconformal

\begin{document}$\beta$\end{document}

contributions into the QCD coupling constant. The PMC predictions satisfy the requirements of renormalization group invariance, including renormalization scheme independence, and the PMC scales accurately reflect the virtuality of the underlying production subprocesses. By using the PMC, an improved prediction for the

\begin{document}$t\bar{t}$\end{document}

production cross-section is obtained without scale ambiguities, which in turn provides a precise value for the top-quark pole mass. Moreover, the prediction of PMC calculations that the magnitudes of higher-order PMC predictions are well within the error bars predicted from the known lower-order has been demonstrated for the top-quark pair production. The resulting determination of the top-quark pole mass,

\begin{document}$m_t^{\rm{pole}}=172.5\pm1.4$\end{document}

GeV, from the LHC measurement at

\begin{document}$\sqrt{S}=13$\end{document}

TeV agrees with the current world average cited by the Particle Data Group (PDG). The PMC prediction provides an important high-precision test of the consistency of pQCD and the SM at

\begin{document}$\sqrt{S}=13$\end{document}

TeV with previous LHC measurements at lower CM energies.

Weak decays of ${\boldsymbol \Xi^{(')}_{\boldsymbol c}\to \boldsymbol\Xi }$ in the light-front quark model

Hong-Wei Ke, Qing-Qing Kang, Xiao-Hai Liu, Xue-Qian Li

2021, 45(11): 113103. doi: 10.1088/1674-1137/ac1c66

HTML

PDF

Abstract:
Without contamination from the final state interactions, the calculation of the branching ratios of semileptonic decays

\begin{document}$ \Xi^{(')}_{c}\to\Xi+e^+\nu_e $\end{document}

may provide further information about the inner structure of charmed baryons. Moreover, by studying such processes, one can better determine the form factors of

\begin{document}$ \Xi_c\to\Xi $\end{document}

that can be further applied to relevant estimates. In this study, we used the light-front quark model to carry out computations where the three-body vertex functions for

\begin{document}$ \Xi_c $\end{document}

and

\begin{document}$ \Xi $\end{document}

are employed. To fit the new data of the Belle II, we re-adjusted the model parameters to obtain

\begin{document}$ \beta_{s[sq]} = 1.07 $\end{document}

GeV, which is 2.9 times larger than

\begin{document}$ \beta_{s\bar s} = 0.366 $\end{document}

GeV. This value may imply that the

\begin{document}$ ss $\end{document}

pair in

\begin{document}$ \Xi $\end{document}

constitutes a more compact subsystem. Furthermore, we investigated the non-leptonic decays of

\begin{document}$ \Xi^{(')}_c\to \Xi $\end{document}

, which will be experimentally measured soon. Thus, our model will be tested in terms of consistency with the new data.

Cosmological implications of a B − L charged hidden scalar: leptogenesis and gravitational waves

Ligong Bian, Wei Cheng, Huai-Ke Guo, Yongchao Zhang

2021, 45(11): 113104. doi: 10.1088/1674-1137/ac1e09

HTML

PDF

Abstract:
In this study, we investigated the cosmological implications of a complex singlet scalar

\begin{document}$ {\cal{S}}$\end{document}

with non-trivial

\begin{document}$ B-L$\end{document}

charges in the conformal

\begin{document}$ U(1)_{B-L}$\end{document}

theory. It was found that, in a sizable region of parameter space,

\begin{document}$ {\cal{S}}$\end{document}

may disturb the resonant leptogenesis mechanism, which is used to generate baryon asymmetry, and affect the symmetry breaking dynamics in the strong first order phase transition. The stochastic gravitational waves (GWs) produced at the phase transition can be probed in future GW experiments. The GW searches prefer a relatively light

\begin{document}$ {\cal{S}}$\end{document}

at the TeV-scale; however, this is difficult to detect directly at future high-energy colliders.

Production of light-flavor and single-charmed hadrons in pp collisions at ${ \sqrt{\boldsymbol s} = {\bf 5.02 }}$ TeV in an equal-velocity quark combination model

Hai-hong Li, Feng-lan Shao, Jun Song

2021, 45(11): 113105. doi: 10.1088/1674-1137/ac1ef9

HTML

PDF

Abstract:
We apply an equal-velocity quark combination model to study the production of light-flavor hadrons and single-charmed hadrons at midrapidity in the

\begin{document}$ pp $\end{document}

collisions at

\begin{document}$ \sqrt{s} = 5.02 $\end{document}

TeV. We find that the experimental data for the

\begin{document}$ p_{T} $\end{document}

spectra of

\begin{document}$ \Omega $\end{document}

and

\begin{document}$ \phi $\end{document}

exhibit the quark number scaling property, which clearly indicates the quark combination mechanism at hadronization. Experimental data for the

\begin{document}$ p_T $\end{document}

spectra of

\begin{document}$ p $\end{document}

,

\begin{document}$ \Lambda $\end{document}

,

\begin{document}$ \Xi $\end{document}

,

\begin{document}$ \Omega $\end{document}

,

\begin{document}$ \phi $\end{document}

, and

\begin{document}$ K^{*0} $\end{document}

are systematically described by the model. The non-monotonic

\begin{document}$ p_{T} $\end{document}

dependence of the

\begin{document}$ \Omega/\phi $\end{document}

ratio is naturally explained, and we find that it is closely related to the shape of the logarithm of the strange quark

\begin{document}$ p_{T} $\end{document}

distribution. Using the

\begin{document}$ p_{T} $\end{document}

spectra of light-flavor quarks obtained from light-flavor hadrons and the

\begin{document}$ p_T $\end{document}

spectrum of charm quarks, which is consistent with perturbative QCD calculations, the experimental data for differential cross-sections of

\begin{document}$ D^{0,+} $\end{document}

,

\begin{document}$ D_{s}^{+} $\end{document}

, and

\begin{document}$ \Lambda_{c}^{+} $\end{document}

as functions of

\begin{document}$ p_{T} $\end{document}

are systematically described. We predict the differential cross-sections of

\begin{document}$ \Xi_{c}^{0,+} $\end{document}

and

\begin{document}$ \Omega_{c}^{0} $\end{document}

. The ratio

\begin{document}$ \Xi_{c}^{0,+}/D^{0} $\end{document}

in our model is approximately 0.16, and

\begin{document}$ \Omega_{c}^{0}/D^{0} $\end{document}

is approximately 0.012, owing to the cascade suppression of strangeness. In addition, the predicted

\begin{document}$ \Xi_{c}^{0,+}/D^{0} $\end{document}

and

\begin{document}$ \Omega_{c}^{0}/D^{0} $\end{document}

ratios exhibit the non-monotonic dependence on

\begin{document}$ p_{T} $\end{document}

in the low

\begin{document}$ p_{T} $\end{document}

range.

2021 Vol. 45, No. 11