2,261 research outputs found

    Effects of ZbZ_b states and bottom meson loops on Υ(4S)→Υ(1S,2S)π+π−\Upsilon(4S) \to \Upsilon(1S,2S) \pi^+\pi^- transitions

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    We study the dipion transitions Υ(4S)→Υ(nS)π+π−\Upsilon(4S) \rightarrow \Upsilon(nS) \pi^+\pi^- (n=1,2)(n=1,2). In particular, we consider the effects of the two intermediate bottomoniumlike exotic states Zb(10610)Z_b(10610) and Zb(10650)Z_b(10650) as well as bottom meson loops. The strong pion-pion final-state interactions, especially including channel coupling to KKˉK\bar{K} in the SS-wave, are taken into account model-independently by using dispersion theory. Based on a nonrelativistic effective field theory we find that the contribution from the bottom meson loops is comparable to those from the chiral contact terms and the ZbZ_b-exchange terms. For the Υ(4S)→Υ(2S)π+π−\Upsilon(4S) \rightarrow \Upsilon(2S) \pi^+\pi^- decay, the result shows that including the effects of the ZbZ_b-exchange and the bottom meson loops can naturally reproduce the two-hump behavior of the ππ\pi\pi mass spectra. Future angular distribution data are decisive for the identification of different production mechanisms. For the Υ(4S)→Υ(1S)π+π−\Upsilon(4S) \rightarrow \Upsilon(1S) \pi^+\pi^- decay, we show that there is a narrow dip around 1 GeV in the ππ\pi\pi invariant mass distribution, caused by the final-state interactions. The distribution is clearly different from that in similar transitions from lower Υ\Upsilon states, and needs to be verified by future data with high statistics. Also we predict the decay width and the dikaon mass distribution of the Υ(4S)→Υ(1S)K+K−\Upsilon(4S) \rightarrow \Upsilon(1S) K^+ K^- process.Comment: 25 pages, 8 figures, predictions of the decay width and the dikaon mass distribution of the Υ(4S)→Υ(1S)K+K−\Upsilon(4S) \rightarrow \Upsilon(1S) K^+ K^- process added, more discussions adde

    Revealing the mystery of the double charm tetraquark in pppp collision

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    A novel approach is proposed to probe the nature of the double charm tetraquark through the measurement of production asymmetry between Tcˉcˉ−T_{\bar{c}\bar{c}}^- and Tcc+T_{cc}^+ in pppp collisions. When comparing two theoretical pictures, the compact tetraquark and molecular pictures, we find that the compact tetraquark picture exhibits a significantly larger production asymmetry and an order of magnitude lower total cross section compared to the molecular picture, enabling the unambiguous determination of the tetraquark's internal structure. Additionally, distinctive differences in the transverse momentum (pTp_\mathrm{T}) and rapidity (yy) distributions of Tcˉcˉ−T_{\bar{c}\bar{c}}^- and Tcc+T_{cc}^+ cross sections emerge, particularly at pT≈2 GeVp_\mathrm{T}\approx 2~\mathrm{GeV} and y≈±6y\approx \pm 6. The difference between particles and antiparticles in a large rapidity region is attributed to the behavior of the residual udud diquarks within the proton. Our work extends to the exploration of other double heavy tetraquark candidates, offering a versatile approach to advance our understanding of exotic hadronic states in particle physics.Comment: 6 pages, 3 figure

    Survivin is a prognostic marker and therapeutic target for extranodal, nasal-type natural killer/T cell lymphoma.

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    Background: The relationship between survivin and extranodal, nasal-type natural killer/T cell lymphoma (ENKTCL) was unclearly established yet. We here studied the potential prognostic roles of survivin and its implication as a target in ENKTCL therapy. Methods: ENKTCL patients\u27 peripheral blood were collected and tested by ELISA. ENKTCL cell lines were cultured with or without survivin inhibitor and tested by MTT and Flow cytometry. According to the gene expression profiles from the ArrayExpress Archive under E-TABM-702, survivin co-regulated cluster was established by Coupled Two-way Clustering Algorithm. Results: Seventeen point six percent of total 17 ENKTCL patients were serum survivin-positive. These patients had poorer outcome than that of negative cases (P Conclusions: We concluded that survivin was a potential prognostic marker and a critical regulatory molecule in the pathological process of ENKTCL. It would be a promising target in drugs discovery for ENKTCL therapy

    Deep quantum neural networks equipped with backpropagation on a superconducting processor

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    Deep learning and quantum computing have achieved dramatic progresses in recent years. The interplay between these two fast-growing fields gives rise to a new research frontier of quantum machine learning. In this work, we report the first experimental demonstration of training deep quantum neural networks via the backpropagation algorithm with a six-qubit programmable superconducting processor. In particular, we show that three-layer deep quantum neural networks can be trained efficiently to learn two-qubit quantum channels with a mean fidelity up to 96.0% and the ground state energy of molecular hydrogen with an accuracy up to 93.3% compared to the theoretical value. In addition, six-layer deep quantum neural networks can be trained in a similar fashion to achieve a mean fidelity up to 94.8% for learning single-qubit quantum channels. Our experimental results explicitly showcase the advantages of deep quantum neural networks, including quantum analogue of the backpropagation algorithm and less stringent coherence-time requirement for their constituting physical qubits, thus providing a valuable guide for quantum machine learning applications with both near-term and future quantum devices.Comment: 7 pages (main text) + 11 pages (Supplementary Information), 10 figure

    Dirac semimetal PdTe2 temperature-dependent quasiparticle dynamics and electron-phonon coupling

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    Dirac semimetal PdTe2 single-crystal temperature-dependent ultrafast carrier and phonon dynamics were studied using ultrafast optical pump-probe spectroscopy. Two distinct carrier and coherent phonons relaxation processes were identified in the 5 K - 300 K range. Quantitative analysis revealed a fast relaxation process ({\tau}_f) occurring on a subpicosecond time scale which originated from electron-phonon thermalization. This was followed by a slower relaxation process ({\tau}_s) with a time scale of ~ 7-9.5 ps which originated from phonon-assisted electron-hole recombination. Two significant vibrational modes resolved at all measured temperatures and corresponded to Te atoms in-plane (E_g), and out-of-plane (A_1g), motion. As temperature increased both phonon modes softened markedly. A_1g mode frequency monotonically decreased as temperature increased. Its damping rate remained virtually unchanged. As expected, E_g decreased uniformly as temperatures rose. At temperatures above 80 K, there was insignificant change. Test results suggested that pure dephasing played an important role in the relaxation processes. PdTe2 phonon is thought responsible for its superconductive properties. Examining phonons behavior should improve the understanding of its complex superconductivity.Comment: 6 pages, 4 figure

    Expression and Role of the Calcium-Sensing Receptor in Rat Peripheral Blood Polymorphonuclear Neutrophils

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    The calcium-sensing receptors (CaSRs) play an important role in many tissues and organs that are involved in inflammatory reactions. Peripheral blood polymorphonuclear neutrophils (PMNs) are important inflammatory cells. However, the expression and functions of CaSR in peripheral blood PMNs are still not reported. In this study, we collected rat peripheral blood PMNs to observe the relationship between CaSR and PMNs. From the results, we found first that the CaSR protein was expressed in PMNs, and it increased after PMNs were activated with fMLP. In addition, CaSR activator cincalcet promoted the expression of CaSR and P-p65 (NF-κB signaling pathway protein) and Bcl-xl (antiapoptosis protein), and it increased the secretion of interleukin-6 (IL-6) and myeloperoxidase (MPO); meanwhile, it decreased proapoptosis protein Bax expression and the production of IL-10 and reactive oxygen species (ROS). At the same time, cincalcet also decreased the PMN apoptosis rate analyzed by flow cytometry. However, CaSR inhibitor NPS-2143 and NF-κB signaling pathway inhibitor PDTC reverse the results cited earlier. All of these results indicated that CaSR can regulate PMN functions and status to play a role in inflammation, which is probably through the NF-κB signaling pathway

    The Hidden Nematic Fluctuations in the Triclinic (Ca0.85La0.15)10(Pt3As8)(Fe2As2)5 Superconductor Revealed by Ultrafast Optical Spectroscopy

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    We reported the quasiparticle relaxation dynamics of an optimally doped triclinic iron-based superconductor (Ca0.85_{0.85}La0.15_{0.15})10_{10}(Pt3_3As8_8)(Fe2_2As2_2)5_5 with bulk TcT_c = 30 K using polarized ultrafast optical pump-probe spectroscopy. Our results reveal anisotropic transient reflectivity induced by nematic fluctuations develops below TnemT_{nem} ≈\approx 120 K and persists in the superconducting states. Measurements under high pump fluence reveal three distinct, coherent phonon modes at frequencies of 1.6, 3.5, and 4.7 THz, corresponding to A1g(1)A_{1g}(1), EgE_g, and A1g(2)A_{1g}(2) modes, respectively. The high-frequency A1g(2)A_{1g}(2) mode corresponds to the cc-axis polarized vibrations of FeAs planes with a nominal electron-phonon coupling constant λA1g(2)\lambda _{A_{1g}(2)} ≈\approx 0.139 ±\pm 0.02. Our findings suggest that the superconductivity and nematic state are compatible but competitive at low temperatures, and the A1gA_{1g} phonons play an important role in the formation of Cooper pairs in (Ca0.85_{0.85}La0.15_{0.15})10_{10}(Pt3_3As8_8)(Fe2_2As2_2)5_5.Comment: 6 pages, 3 figures and Supplemental Material

    Nesting-driven antiferromagnetic order in Kondo lattice CePd5Al2

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    We investigated the electronic structure of the antiferromagnetic Kondo lattice CePd5Al2 using high-resolution angle-resolved photoemission spectroscopy. The experimentally determined band structure of the conduction electrons is predominated by the Pd 4d character. It contains multiple hole and electron Fermi pockets, in good agreement with density functional theory calculations. The Fermi surface is folded over Q0 = (0, 0, 1), manifested by Fermi surface reconstruction and band folding. Our results suggest that Fermi surface nesting drives the formation of antiferromagnetic order in CePd5Al2.Comment: 6 pages,3 figur
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