The European Physical Journal C最新文献

In this addendum, we change the sign of the squared length scale parameter ((l^2rightarrow -l^2)) in the conformal factor presented in Eq. (36) of the original article to explore its effects on the observational frequency shift. We make this change of sign because it removes an unnecessary physical singularity at (r=l) from the original expression of the curvature invariants of the conformal metric. Then, we apply this correction to all the equations involving the parameter (l^2) and find that under this modification in the conformal mapping, the relations of redshift/blueshift and gravitational redshift change. The new equations are represented in Eqs. (44)–(45) and their behavior are illustrated in Figs. 1, 2 and 3, corresponding to the equations and figures in the original article. Additionally, due to this change of the sign in the squared length scale parameter, we discuss the effects of this parameter on the observational frequency shift which differ from those presented in section 5 of the original article. We also note that the expressions as well as corresponding figures and discussions presented in the original paper are correct for that choice of the conformal factor.

We consider the (Z_5) two-component dark matter model within the framework of the Type-II seesaw mechanism. Due to the new annihilation processes related to triplets, the light component cannot necessarily be dominant in the dark matter relic density, which is different from the two singlet extension of the standard model with a (Z_5) symmetry. The model is considered to explain the excess of electron-positron flux measured by the AMS-02 Collaborations in this work, which is encouraged by the decay of the triplets arising from dark matter annihilations in the Galactic halo. We discuss the cases of the light and heavy components determining dark matter density within a viable parameter space satisfying relic density and direct detection constraints, and by fitting the antiproton spectrum observed in the PAMELA and AMS experiments, we find that the parameter space is flexible and the electron-positron flux excess can be obtained in both cases with the mass of two dark matter particles being larger than that of the triplets’.

Inspired by the experimental measurement of the charmed hadronic state X(6900), we calculate the mass spectra of tetraquark hybrid states with configuration of ([8_{c}]_{Qbar{Q}} otimes [8_{c}]_{G} otimes [8_{c}]_{Qbar{Q}}) in color, by virtue of QCD sum rules. The two feasible types of currents with quantum numbers (J^{PC} = 0^{++}) and (0^{-+}) are investigated, in which the contributions from operators up to dimension six are taken into account in operator product expansion (OPE). In the end, we find that, in charm sector, the tetracharm hybrid states with quantum number (0^{++}) has a mass of about (6.98^{+0.16}_{-0.14} , text {GeV}), while (0^{-+}) state mass is about (7.26^{+0.16}_{-0.15} , text {GeV}). The results overlap with the experimental observations, suggesting potential tetracharm hybrid interpretations. In bottom sector, calculation shows that the masses of tetrabottom hybrid states with quantum numbers (0^{++}) and (0^{-+}) are (19.30^{+0.16}_{-0.17} , text {GeV}) and (19.50^{+0.17}_{-0.17} , text {GeV}), respectively, which are left for future experimental confirmation.

Heavy neutral leptons N are introduced to explain the tiny neutrino masses via the seesaw mechanism. For proper small mixing parameter (V_{ell N},) the heavy neutral leptons N become long-lived, which leads to the displaced vertex signature at colliders. In this paper, we consider the displaced heavy neutral lepton from the neutrinophilic Higgs doublet (Phi _nu ) decay. The new Higgs doublet with MeV scale VEV can naturally explain the tiny neutrino masses with TeV scale N. Different from current experimental searches via the (W^pm rightarrow ell ^pm N) decay, the branching ratios of new decays as (H^pm rightarrow ell ^pm N) are not suppressed when (|V_{ell N}|gtrsim 10^{-16}.) Therefore, a larger parameter space is expected to be detected at colliders. We then investigate the promising region at the 14 TeV HL-LHC and the 3 TeV CLIC. According to our simulation, the DV signature could probe (|V_{ell N}|^2gtrsim 10^{-18}) with (m_N<m_{H^+},) which covers the seesaw predicted value (|V_{ell N}|^2sim m_nu /m_N.) We could probe (m_{H^+}lesssim 1100) GeV at the 14 TeV HL-LHC and (m_{H^+}lesssim 1490) GeV at the 3 TeV CLIC.

Considering the nonfactorizable QED corrections, the branching ratios and ratios of branching ratios (R(D_{s}^{({*})})) for the semileptonic (overline{B}_{s}) ({rightarrow }) (D_{s}^{(*)} {ell } bar{nu }_{ell }) decays are reevaluated. It is found that (a) the QED contributions can enhance the branching ratios and reduce the ratios (R(D_{s}^{({*})})). (b) The SU(3) flavor symmetry holds basically well in the ratios R(D)-(R(D^{*})) for the semileptonic charmed (overline{B}_{u,d,s}) decays. (c) The current theoretical uncertainties of branching ratios (mathcal{B}(overline{B}_{s} {rightarrow } D_{s}^{*} {ell } bar{nu }_{ell })) from the form factors are very large.

In this work, we propose to employ the concept of photon self-interaction for axion detection. In particular, we derive the interaction Hamiltonian for photons via axions in a ring cavity. We show that when the incoming photons are considered in plane-wave basis, the interaction vanishes. However, when the realistic case of photon wavepackets are assumed, a self-interaction whose strength is proportional to the size of the wavepacket and the cavity length exists. Under specific conditions, we find that the axion-mediated interaction dominates the gravitationally induced self-interaction. We discuss the implications of this setup for axion detection, focusing on the range of axion mass, (10^{-10}~text {eV}<m_a<10^{-4}~text {eV}) for which the best accuracy of coupling constants is constrained in some cases to (g_{agamma gamma }> 9 times 10^{-12}~ text {GeV}^{-1}).

In this paper, we investigate the masses of heavy pentaquark states under the influence of a spin-spin interaction term within a torsion-free fractal space-time with a point-like global monopole. The application and presence of fractional derivative is established from the outset. New operators are constructed using the definition of fractional derivative, and fractional-order Schrödinger equation is derived from these operators. The Hamiltonian operator is constructed with a two-part interaction potential: a spin-independent part containing Cornell potential, inversely quadratic and harmonic oscillator terms and a spin-dependent part containing a spin-spin interaction term to break the degeneracy between spin singlets and triplets. The spin dependence in our model arises from the harmonic approximation of the Gaussian function included in the spin-spin interaction term. This approximation facilitates obtaining analytical solutions for the bound states of heavy pentaquarks, expressed in terms of bi-confluent Heun functions. To achieve precise mass calculations for these pentaquarks using our model, various factors have been considered, including spin configurations, color and flavor combinations. Thus, we obtained the ground state masses for pentaquark containing two heavy quarks and having spin-parity (frac{1}{2}^{-}), (frac{3}{2}^{-}) and (frac{5}{2}^{-}). Our results show consistency with previous calculations and are improved when experimental data are available, highlighting the relevance of fractional models and topological defects in heavy pentaquark mass calculations.

In this paper, we will propose a novel interacting vacuum model whose energy flow is modeled according to the free Dirac–Born–Infeld theory and hydrodynamically realized via the (Modified) Berthelot equation of state. By employing dynamical system techniques, we will identify a suitable late-time attractor which can realistically account for the present-day configuration of the universe, addressing the coincidence problem, supporting an accelerated expansion without breaking any energy condition, free from fine-tuning issues on initial conditions, and stable also at the perturbative level. Analytical closed-form results for the redshift evolution of both vacuum energy and dark matter will be presented. We will provide as well two distinctive fingerprints of our model, useful for its sharp identification inside the rich zoo of literature interacting vacuum models: a vacuum equation of state via geometric curvature scalars, and an analytical relationship between the statefinder variables. We will eventually show that our scenario actually consists in a running (or decaying) vacuum, with consequent production of dark matter particles, also comparing and contrasting its cosmological applicability with that of other known interacting vacuum paradigms. Our work therefore belongs to the line of research scrutinizing the relevance of quantum field theory approaches to the taming of current observational tensions.

The indirect production mechanisms of fully charmed tetraquark are analyzed using the NRQCD factorization and Suzuki approach, respectively. The process first produces a heavy charm quark through Higgs, (W^+), or (Z^0) decay, and then the resulting charm quark evolves into an S-wave fully charmed tetraquark state with quantum number (J^{PC}), including (0^{++}), (1^{+-}), and (2^{++}), via the fragmentation function. While the transverse momentum (langle vec {q}_T^2rangle ) in Suzuki approach ranges from 2.01 to 299.04 (text {GeV}^2), the numerical results obtained from these two approaches are consistent with each other. The decay widths, branching ratios, and produced events would be predicted at LHC and CEPC, respectively. The corresponding theoretical uncertainty of heavy quark mass (m_c) and distribution of energy fraction are also presented. The results show that the contribution for the production of (T_{4c}) through (W^+) decay channel at LHC is relatively large. At CEPC, a sufficient number of (T_{4c}) events are produced through (Z^0) decays, which is likely to be detected in future experiments.