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Motivated by the LHCb observation of exotic states X 0 , 1 ( 2900 ) with four open quark flavors in the D - K + invariant mass distribution in the decay channel B ± → D + D - K ± , we study the spectrum and decay properties of the open charm tetraquarks. Using the two-body chromomagnetic interactions, we find that the two newly observed states can be interpreted as a radial excited tetraquark with J P = 0 + and an orbitally excited tetraquark with J P = 1 - , respectively. We then explore the mass and decays of the other flavor-open tetraquarks made of s u d ¯ c ¯ and d s u ¯ c ¯ , which are in the 6 ¯ or 15 representation of the flavor SU(3) group. We point that these two states can be found through the decays: X d s u ¯ c ¯ ( ′ ) → ( D - K - , D s - π - ) , and X s u d ¯ c ¯ ( ′ ) → D s - π + . We also apply our analysis to open bottom tetraquark X b and predict their masses. The open-flavored X b can be discovered through the following decays: X u d s ¯ b ¯ → B 0 K + , X d s u ¯ b ¯ ( ′ ) → ( B 0 K - , B s 0 π - ) , and X s u d ¯ b ¯ ( ′ ) → B s 0 π + .

Analyses of heavy mesons and baryons hadronic charmless decays using the flavor SU(3) symemtry can be formulated in two different forms. One is to construct the SU(3) irreducible representation amplitude by decomposing effective Hamiltonian, and the other is to draw the topological diagrams. In the flavor SU(3) limit, we study various B / D → P P , V P , V V , B c → D P / D V decays, and two-body nonleptonic decays of beauty/charm baryons, and demonstrate that when all terms are included these two ways of analyzing the decay amplitudes are completely equivalent. Furthermore we clarify some confusions in drawing topological diagrams using different ways of describing beauty/charm baryons.

A bstract We explore simple Higgs-portal models of dark matter (DM) with spin 1/2, 3/2, and 1, respectively, applying to them constraints from the LUX and PandaX-II direct detection experiments and from LHC measurements on the 125-GeV Higgs boson. With only one Higgs doublet, we find that the spin-1/2 DM having a purely scalar effective coupling to the doublet is viable only in a narrow range of mass near the Higgs pole, whereas the vector DM is still allowed if its mass is also close to the Higgs pole or exceeds 1.4 TeV, both in line with earlier analyses. Moreover, the spin-3/2 DM is in a roughly similar situation to the spin-1/2 DM, but has surviving parameter space which is even more restricted. We also consider the two-Higgs-doublet extension of each of the preceding models, assuming that the expanded Yukawa sector is that of the two-Higgs-doublet model of type II. We show that in these two-Higgs-doublet-portal models significant portions of the DM mass regions excluded in the simplest scenarios by direct search bounds can be reclaimed due to suppression of the effective DM interactions with nucleons at some ratios of the CP -even Higgs bosons’ couplings to the up and down quarks. The regained parameter space contains areas which can yield a DM-nucleon scattering cross-section that is far less than its current experimental limit or even goes below the neutrino-background floor.

A bstract Direct searches for dark matter (DM) by the LUX and PandaX-II Collaborations employing xenon-based detectors have recently come up with the most stringent limits to date on the spin-independent elastic scattering of DM off nucleons. For Higgs-portal scalar DM models, the new results have precluded any possibility of accommodating low-mass DM as suggested by the DAMA and CDMS II Si experiments utilizing other target materials, even after invoking isospin-violating DM interactions with nucleons. In the simplest model, SM+D, which is the standard model plus a real singlet scalar named darkon acting as the DM candidate, the LUX and PandaX-II limits rule out DM masses roughly from 4 to 450 GeV, except a small range around the resonance point at half of the Higgs mass where the interaction cross-section is near the neutrino-background floor. In the THDM II+D, which is the type-II two-Higgs-doublet model combined with a darkon, the region excluded in the SM+D by the direct searches can be recovered due to suppression of the DM effective interactions with nucleons at some values of the ratios of Higgs couplings to the up and down quarks, making the interactions significantly isospin-violating. However, in either model, if the 125-GeV Higgs boson is the portal between the dark and SM sectors, DM masses less than 50 GeV or so are already ruled out by the LHC constraint on the Higgs invisible decay. In the THDM II+D, if the heavier CP -even Higgs boson is the portal, theoretical restrictions from perturbativity, vacuum stability, and unitarity requirements turn out to be important instead and exclude much of the region below 100 GeV. For larger DM masses, the THDM II+D has plentiful parameter space that corresponds to interaction cross-sections under the neutrino-background floor and therefore is likely to be beyond the reach of future direct searches without directional sensitivity.

Intervertebral disc degeneration (IDD) is a common clinical degenerative disease of the spine. A series of factors, such as inflammation, oxidative stress and mechanical stress, promote degradation of the extracellular matrix (ECM) of the intervertebral discs (IVD), leading to dysfunction and structural destruction of the IVD. Nuclear factor‐κB (NF‐κB) transcription factor has long been regarded as a pathogenic factor of IDD. Therefore, NF‐κB may be an ideal therapeutic target for IDD. As NF‐κB is a multifunctional functional transcription factor with roles in a variety of biological processes, a comprehensive understanding of the function and regulatory mechanism of NF‐κB in IDD pathology will be useful for the development of targeted therapeutic strategies for IDD, which can prevent the progression of IDD and reduce potential risks. This review discusses the role of the NF‐κB signalling pathway in the nucleus pulposus (NP) in the process of IDD to understand pathological NP degeneration further and provide potential therapeutic targets that may interfere with NF‐κB signalling for IDD therapy. Intervertebral disc degeneration (IDD) is a common clinical degenerative disease of the spine. A series of factors, such as inflammation, oxidative stress, and mechanical stress, promote degradation of the extracellular matrix (ECM) of the intervertebral discs (IVD), leading to dysfunction and structural destruction of the IVD. Nuclear factor‐κB (NF‐κB) transcription factor has long been regarded as the pathogenic factor of IDD. Therefore, NF‐κB may be an ideal therapeutic target for IDD. As NF‐κB is a multifunctional functional transcription factor with roles in a variety of biological processes, a comprehensive understanding of the function and regulatory mechanism of NF‐κB in IDD pathology will be useful for the development of targeted therapeutic strategies for IDD, which can prevent the progression of IDD and reduce potential risks. This review discusses the role of the NF‐κB signalling pathway in the nucleus pulposus (NP) in the process of IDD to understand pathological NP degeneration further and provide potential therapeutic targets that may interfere with NF‐κB signalling for IDD therapy. ​

The costs for solar photovoltaics, wind, and battery storage have dropped markedly since 2010, however, many recent studies and reports around the world have not adequately captured such dramatic decrease. Those costs are projected to decline further in the near future, bringing new prospects for the widespread penetration of renewables and extensive power-sector decarbonization that previous policy discussions did not fully consider. Here we show if cost trends for renewables continue, 62% of China’s electricity could come from non-fossil sources by 2030 at a cost that is 11% lower than achieved through a business-as-usual approach. Further, China’s power sector could cut half of its 2015 carbon emissions at a cost about 6% lower compared to business-as-usual conditions. The decrease in costs of renewable energy and storage has not been well accounted for in energy modelling, which however will have a large effect on energy system investment and policies. Here the authors incorporated recent decrease in costs of renewable energy and storages to refine the pathways to decarbonize China’s power system by 2030 and show that if such cost trends for renewables continue, more than 60% of China’s electricity could come from non-fossil sources by 2030 at a cost that is about 10% lower than achieved through a business-as-usual approach.

A bstract We consider decays of B and K mesons into a pseudo-scalar or vector meson plus missing energy. Within the SM, these modes originate from flavor changing neutral current (FCNC) processes with two neutrinos in the final state. In this paper we consider the experimental upper bounds on these modes and interpret the difference between these bounds and the SM prediction as a window into new light invisible particles. In particular we consider the case where some new symmetry requires the new particles to be produced in pairs. We first construct the general low energy effective Lagrangian coupling an FCNC with two dark sector particles of spin zero, one-half and one. We then present numerical estimates for the constraints that can be placed on these interactions, finding that an effective new physics scale from O (10)- O (10 11 ) GeV can be probed, with the exact value strongly depending on the interaction structure as well as the mass of the invisible particle. For we incorporate into our constraints the effect of using only the signal regions of NA62, and for the q 2 -dependent efficiency of Belle II.

Superplastic forming and diffusion bonding (SPF/DB) has been recognized as a viable manufacturing technology. However, the basic understanding of grain size and its effects on the quality of diffusion bonds is still limited. In this study, a certain type of SP700 alloy with different grain sizes is bonded at superplastic temperature. The experimental results indicate that the same materials, if coarse-grained, may not readily bond under identical conditions of pressure, temperature, and time. This type of bonding is possible because of the presence of many grain boundaries in fine-grained materials that act as short-circuit paths for diffusion. In addition, grain-boundary migration is also faster in fine-grained than in coarse-grained materials. Fractographic studies show that the dimples on the coarse-grained specimen have large dimensions compared with that in the fine-grained material, indicating that heterogeneous deformation develops in the coarse-grained specimen during tension.

A bstract General flavor changing Goldstone boson (GB) interactions with fermions from a spontaneous global U(1) G symmetry breaking are discussed. This GB may be the Axion, solving the strong QCD CP problem, if there is a QCD anomaly for the assignments of quarks U(1) G charge. Or it may be the Majoron, producing seesaw Majorana neutrino masses by lepton number violation, if the symmetry breaking scale is much higher than the electroweak scale. It may also, in principle, play the roles of Axion and Majoron simultaneously as far as providing solution for the strong CP problem and generating a small Majorana neutrino masses are concerned. Great attentions have been focused on flavor conserving GB interactions. Recently flavor changing Axion and Majoron models have been studied in the hope to find new physics from rare decays in the intensity frontier. In this work, we will provide a systematic model building aspect study for flavor changing neutral current (FCNC) GB interactions in the fermion sectors, or separately in the quark, charged lepton and neutrino sectors and will identify in detail the sources of FCNC interactions in a class of beyond standard model with a spontaneous global U(1) G symmetry breaking. We also provide a general proof of the equivalence of using physical GB components and GB broken generators for calculating GB couplings to two gluons and two photons, and discuss some issues related to spontaneous CP violation models. Besides, we will also provide some details for obtaining FCNC GB interactions in several popular models, such as the Type-I, -II, -III seesaw and Left-Right symmetric models, and point out some special features in these models.

A bstract The LHCb Collaboration has recently reported evidence for the rare hyperon decay Σ + → pμ + μ − that is consistent with the standard model expectation. Motivated by this new result we revisit the calculation of this mode including both long and short distance contributions. In the standard model this mode is completely dominated by long distance physics and thus subject to large uncertainties. We present a range of predictions for the rate, the dimuon invariant mass spectrum, and a muon polarization asymmetry that covers these uncertainties as well as known constraints. We study the interplay between short and long distance contributions which could result in additional asymmetries, but we find that they are negligible within the standard model. We propose a parameterization of these asymmetries in terms of a couple of constants that can arise from new physics.