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Papavassiliou, J. (2022). Emergence of mass in the gauge sector of QCD. Chin. Phys. C, 46(11), 112001–23pp.
Abstract: It is currently widely accepted that gluons, while massless at the level of the fundamental QCD Lagrangian, acquire an effective mass through the non-Abelian implementation of the classic Schwinger mechanism. The key dynamical ingredient that triggers the onset of this mechanism is the formation of composite massless poles inside the fundamental vertices of the theory. These poles enter the evolution equation of the gluon propagator and nontrivially affect the way the Slavnov-Taylor identities of the vertices are resolved, inducing a smoking-gun displacement in the corresponding Ward identities. In this article, we present a comprehensive review of the pivotal concepts associated with this dynamical scenario, emphasizing the synergy between functional methods and lattice simulations and highlighting recent advances that corroborate the action of the Schwinger mechanism in QCD.
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Arrechea, J., Delhom, A., & Jimenez-Cano, A. (2021). Inconsistencies in four-dimensional Einstein-Gauss-Bonnet gravity. Chin. Phys. C, 45(1), 013107–8pp.
Abstract: We attempt to clarify several aspects concerning the recently presented four-dimensional Einstein-Gauss-Bonnet gravity. We argue that the limiting procedure outlined in [Phys. Rev. Lett. 124, 081301 (2020)] generally involves ill-defined terms in the four dimensional field equations. Potential ways to circumvent this issue are discussed, alongside remarks regarding specific solutions of the theory. We prove that, although linear perturbations are well behaved around maximally symmetric backgrounds, the equations for second-order perturbations are ill-defined even around a Minkowskian background. Additionally, we perform a detailed analysis of the spherically symmetric solutions and find that the central curvature singularity can be reached within a finite proper time.
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Belle II Collaboration(Abudinen, F. et al), Gomis, P., & Marinas, C. (2020). Measurement of the integrated luminosity of the Phase 2 data of the Belle II experiment. Chin. Phys. C, 44(2), 021001–12pp.
Abstract: From April to July 2018, a data sample at the peak energy of the resonance was collected with the Belle II detector at the SuperKEKB electron-positron collider. This is the first data sample of the Belle II experiment. Using Bhabha and digamma events, we measure the integrated luminosity of the data sample to be (, where the first uncertainty is statistical and the second is systematic. This work provides a basis for future luminosity measurements at Belle II.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Measurement of Xi(++)(cc) production in pp collisions at root s=13 TeV. Chin. Phys. C, 44(2), 022001–11pp.
Abstract: The production of Xi(++)(cc) baryons in proton-proton collisions at a centre-of-mass energy of root s = 13 Tev is measured in the transverse-momentum range 4 < p(T) < 15 GeV/c and the rapidity range 2.0 < y < 4.5. The data used in this measurement correspond to an integrated luminosity of 1.7 fb(-1), recorded by the LHCb experiment during 2016. The ratio of the Xi(++)(cc) production cross-section times the branching fraction of the Xi(++)(cc) -> Lambda K-+(c)-pi(+)pi(+) decay relative to the prompt Lambda(+)(c) production cross-section is found to be (2.22 +/- 0.27 +/- 0.29) x 10(-4), assuming the central value of the measured Xi(++)(cc) lifetime, where the first uncertainty is statistical and the second systematic.
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Wang, Y. F., Yao, D. L., & Zheng, H. Q. (2019). New insights on low energy pi N scattering amplitudes: comprehensive analyses at O (p(3)) level. Chin. Phys. C, 43(6), 064110–22pp.
Abstract: A production representation of partial-wave S matrix is utilized to construct low-energy elastic pion-nucleon scattering amplitudes from cuts and poles on complex Riemann sheets. Among them, the contribution of left-hand cuts is estimated using the O (p(3)) results obtained in covariant baryon chiral perturbation theory within the extendedon-nass-shell scheme. By fitting to data on partial-wave phase shifts, it is indicated that the existences of hidden poles in S-11 and P-11 channels, as conjectured in our previous paper [Eur. Phys. J. C, 78(7): 543 (2018)], are firmly established. Specifically, the pole mass of the S-11 hidden resonance is determined to be (895 +/- 81)-(164 +/- 23)i MeV, whereas, the virtual pole in the P-11 channel locates at (966 +/- 18) MeV. It is found that analyses at the O (p(3)) level improves significantly the fit quality, comparing with the previous O (p(2)) one. Quantitative studies with cautious physical discussions are also conducted for the other S- and P-wave channels.
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