1,478 research outputs found

    Luttinger-volume violating Fermi liquid in the pseudogap phase of the cuprate superconductors

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    Based on the NMR measurements on Bi2_2Sr2x_{2-x}Lax_xCuO6+δ_{6+\delta} (La-Bi2201) in strong magnetic fields, we identify the non-superconducting pseudogap phase in the cuprates as a Luttinger-volume violating Fermi liquid (LvvFL). This state is a zero temperature quantum liquid that does not break translational symmetry, and yet, the Fermi surface encloses a volume smaller than the large one given by the Luttinger theorem. The particle number enclosed by the small Fermi surface in the LvvFL equals the doping level pp, not the total electron number ne=1pn_e=1-p. Both the phase string theory and the dopon theory are introduced to describe the LvvFL. For the dopon theory, we can obtain a semi-quantitative agreement with the NMR experiments.Comment: The final version in PR

    CP Violation for B

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    In the QCD factorization (QCDF) approach we study the direct CP violation in B-0→ρ0(ω)ρ0(ω)→π+π-π+π- via the ρ-ω mixing mechanism. We find that the CP violation can be enhanced by double ρ-ω mixing when the masses of the π+π- pairs are in the vicinity of the ω resonance, and the maximum CP violation can reach 28%. We also compare the results from the naive factorization and the QCD factorization

    Radiative decays of the heavy-quark-spin molecular partner of Tcc+T_{cc}^+

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    With the assumptions that the Tcc+T_{cc}^+ discovered at LHCb is a DDD^{*}D hadronic molecule, using a nonrelativistic effective field theory we calculate the radiative partial widths of TccDDγT_{cc}^* \to D^*D\gamma with TccT_{cc}^* being a DDD^{*}D^{*} shallow bound state and the heavy-quark-spin partner of Tcc+T_{cc}^+. The I=0I=0 DDD^*D rescattering effect with the TccT_{cc} pole is taken into account. The results show that the isoscalar DDD^{\ast} D rescattering can increase the tree-level decay width of Tcc+D+D0γT_{cc}^{\ast +}\rightarrow D^{*+}D^0\gamma by about 50%50\%, while decrease that of Tcc+D0D+γT_{cc}^{\ast +}\rightarrow D^{*0}D^+\gamma by a similar amount. The two-body partial decay widths of the Tcc+T_{cc}^{*+} into Tcc+γT_{cc}^+\gamma and Tcc+π0T_{cc}^+\pi^0 are also calculated, and the results are about 6 keV6~\rm{keV} and 3 keV3~\rm{keV}, respectively. Considering that the DD^* needs to be reconstructed from the DπD\pi or DγD\gamma final state in an experimental measurement, the four-body partial widths of the Tcc+T_{cc}^{*+} into DDγγDD\gamma\gamma and DDπγDD\pi\gamma are explicitly calculated, and we find that the interference effect between different intermediate DDγD^*D\gamma states is small. The total radiative decay width of the TccT_{cc}^* is predicted to be about 24 keV24~\rm{keV}. Adding the hadronic decay widths of TccDDπT_{cc}^* \to D^*D\pi, the total width of the TccT_{cc}^* is finally predicted to be (65±2)(65\pm2) keV.Comment: 27 pages, 13 figures. arXiv admin note: text overlap with arXiv:2211.0247

    Design of variable screw pitch rib snapping roller and residue cutter for corn harvesters

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    The blocking between two snapping rollers will seriously constrict the harvesting efficiency for corn harvester. A variable screw pitch rib snapping roller was developed to solve this problem. The comparative experiment between fixed screw pitch rib snapping rollers and variable screw pitch rib snapping rollers illustrated that variable screw pitch ribs can avoid corn-stalk blocking effectively, and it can improve working efficiency by 56.7%. Conservation tillage with standing corn residue was testified that it had a strong control of soil wind erosion. In order to implement this mode of conservation tillage at a production scale, a cutter was developed in this study. Subsequently, two experiments were conducted, one was to test the cutting ratio (defined as the totally cut off stalk population divided by total stalk population), and the other one was to test standing-residue height

    Impact of residual and intrafractional errors on strategy of correction for image-guided accelerated partial breast irradiation

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    <p>Abstract</p> <p>Background</p> <p>The cone beam CT (CBCT) guided radiation can reduce the systematic and random setup errors as compared to the skin-mark setup. However, the residual and intrafractional (RAIF) errors are still unknown. The purpose of this paper is to investigate the magnitude of RAIF errors and correction action levels needed in cone beam computed tomography (CBCT) guided accelerated partial breast irradiation (APBI).</p> <p>Methods</p> <p>Ten patients were enrolled in the prospective study of CBCT guided APBI. The postoperative tumor bed was irradiated with 38.5 Gy in 10 fractions over 5 days. Two cone-beam CT data sets were obtained with one before and one after the treatment delivery. The CBCT images were registered online to the planning CT images using the automatic algorithm followed by a fine manual adjustment. An action level of 3 mm, meaning that corrections were performed for translations exceeding 3 mm, was implemented in clinical treatments. Based on the acquired data, different correction action levels were simulated, and random RAIF errors, systematic RAIF errors and related margins before and after the treatments were determined for varying correction action levels.</p> <p>Results</p> <p>A total of 75 pairs of CBCT data sets were analyzed. The systematic and random setup errors based on skin-mark setup prior to treatment delivery were 2.1 mm and 1.8 mm in the lateral (LR), 3.1 mm and 2.3 mm in the superior-inferior (SI), and 2.3 mm and 2.0 mm in the anterior-posterior (AP) directions. With the 3 mm correction action level, the systematic and random RAIF errors were 2.5 mm and 2.3 mm in the LR direction, 2.3 mm and 2.3 mm in the SI direction, and 2.3 mm and 2.2 mm in the AP direction after treatments delivery. Accordingly, the margins for correction action levels of 3 mm, 4 mm, 5 mm, 6 mm and no correction were 7.9 mm, 8.0 mm, 8.0 mm, 7.9 mm and 8.0 mm in the LR direction; 6.4 mm, 7.1 mm, 7.9 mm, 9.2 mm and 10.5 mm in the SI direction; 7.6 mm, 7.9 mm, 9.4 mm, 10.1 mm and 12.7 mm in the AP direction, respectively.</p> <p>Conclusions</p> <p>Residual and intrafractional errors can significantly affect the accuracy of image-guided APBI with nonplanar 3DCRT techniques. If a 10-mm CTV-PTV margin is applied, a correction action level of 5 mm or less is necessary so as to maintain the RAIF errors within 10 mm for more than 95% of fractions. Pre-treatment CBCT guidance is not a guarantee for safe delivery of the treatment despite its known benefits of reducing the initial setup errors. A patient position verification and correction during the treatment may be a method for the safe delivery.</p

    Coherent phonon dynamics in spatially separated graphene mechanical resonators

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    Vibrational modes in mechanical resonators provide a promising candidate to interface and manipulate classical and quantum information. The observation of coherent dynamics between distant mechanical resonators can be a key step towards scalable phonon-based applications. Here we report tunable coherent phonon dynamics with an architecture comprising three graphene mechanical resonators coupled in series, where all resonators can be manipulated by electrical signals on control gates. We demonstrate coherent Rabi oscillations between spatially separated resonators indirectly coupled via an intermediate resonator serving as a phonon cavity. The Rabi frequency fits well with the microwave burst power on the control gate. We also observe Ramsey interference, where the oscillation frequency corresponds to the indirect coupling strength between these resonators. Such coherent processes indicate that information encoded in vibrational modes can be transferred and stored between spatially separated resonators, which can open the venue of on-demand phonon-based information processing
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