1,836 research outputs found

    Excited Heavy Quarkonium Production at the LHC through WW-Boson Decays

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    Sizable amount of heavy-quarkonium events can be produced through WW-boson decays at the LHC. Such channels will provide a suitable platform to study the heavy-quarkonium properties. The "improved trace technology", which disposes the amplitude M{\cal M} at the amplitude-level, is helpful for deriving compact analytical results for complex processes. As an important new application, in addition to the production of the lower-level Fock states (QQˉ)[1S]>|(Q\bar{Q'})[1S]> and (QQˉ)[1P]>|(Q\bar{Q'})[1P]>, we make a further study on the production of higher-excited (QQˉ)>|(Q\bar{Q'})>-quarkonium Fock states (QQˉ)[2S]>|(Q\bar{Q'})[2S]>, (QQˉ)[3S]>|(Q\bar{Q'})[3S]> and (QQˉ)[2P]>|(Q\bar{Q'})[2P]>. Here (QQˉ)>|(Q\bar{Q'})> stands for the (ccˉ)>|(c\bar{c})>-charmonium, (cbˉ)>|(c\bar{b})>-quarkonium and (bbˉ)>|(b\bar{b})>-bottomonium respectively. We show that sizable amount of events for those higher-excited states can also be produced at the LHC. Therefore, we need to take them into consideration for a sound estimation.Comment: 7 pages, 9 figures and 6 tables. Typo errors are corrected, more discussions and two new figures have been adde

    1-[3-(4-Methoxy­phen­yl)-6-methyl-1,6-dihydro-1,2,4,5-tetra­zin-1-yl]propanone

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    In the title compound, C13H16N4O2, the central tetra­zine ring adopts an unsymmetrical boat conformation with the two C atoms as flagpoles. This compound can be considered as having homoaromaticity

    Coherent quantum effects through dispersive bosonic media

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    The coherent evolution of two atomic qubits mediated by a set of bosonic field modes is investigated. By assuming a specific encoding of the quantum states in the internal levels of the two atoms we show that entangling quantum gates can be realised, with high fidelity, even when a large number of mediating modes is involved. The effect of losses and imperfections on the gates' operation is also considered in detail.Comment: 7 pages, 10 figure

    (E)-1-[(2-Chloro-5-methyl­pyridin-3-yl)methyl­ene]thiosemicarbazide

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    The title compound, C8H9ClN4S, which has potential insecticidal activity, was synthesized by the reaction of 2-chloro-5-methyl­nicotinaldehyde and thio­semicarbazide. In the crystal structure, the mol­ecules are linked via inter­molecular N—H⋯N, N—H⋯S and N—H⋯Cl hydrogen bonds, forming a three-dimensional network stacked down a

    Comparison Between Single Loading–Unloading Indentation and Continuous Stiffness Indentation

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    Experiments are performed on fused silica, Si, and duplex stainless steel to examine whether the CSM (continuous stiffness indentation) method will provide approximately the “same” results of contact modulus and indentation hardness as those measured from the quasi-static single loading–unloading indentation. The experimental results show that the elastic modulus measured by the CSM method is compatible with that by the quasi-static loading–unloading method for hard materials, while there exists a percentage difference of ∼21.3% between the smallest value and the largest vale of the measured indentation hardnesses from the CSM method for fused silica and a percentage difference of ∼15.3% between the hardnesses measured by the CSM method and the single indentation for duplex stainless steel. The large percentage difference suggests that the indentation hardness measured by the CSM method may not be compatible with that measured by the quasi-static loading–unloading method for hard materials. The finite element results reveal the percentage difference between the indentation hardness at the wave peak and that at the wave valley for the CSM method increases with the increase of the ratio of elastic modulus to yield stress

    Heavy Quarkonium Production at LHC through WW Boson Decays

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    The production of the heavy (ccˉ)(c\bar{c})-quarkonium, (cbˉ)(c\bar{b})-quarkonium and (bbˉ)(b\bar{b})-quarkonium states ((QQˉ)(Q\bar{Q'})-quarkonium for short), via the W+W^+ semi-inclusive decays, has been systematically studied within the framework of the non-relativistic QCD. In addition to the two color-singlet SS-wave states, we also discuss the production of the four color-singlet PP-wave states (QQˉ)(1P1)1>|(Q\bar{Q'})(^1P_1)_{\bf 1}> and (QQˉ)(3PJ)1>(Q\bar{Q'})(^3P_J)_{\bf 1}> (with J=(1,2,3)J=(1,2,3)) together with the two color-octet components (QQˉ)(1S0)8>|(Q\bar{Q'})(^1S_0)_{\bf 8}> and (QQˉ)(3S1)8>|(Q\bar{Q'})(^3S_1)_{\bf 8}>. Improved trace technology is adopted to derive the simplified analytic expressions at the amplitude level, which shall be useful for dealing with the following cascade decay channels. At the LHC with the luminosity L1034cm2s1{\cal L}\propto 10^{34}cm^{-2}s^{-1} and the center-of-mass energy S=14\sqrt{S}=14 TeV, sizable heavy-quarkonium events can be produced through the W+W^+ boson decays, i.e. 2.57×1062.57\times10^6 ηc\eta_c, 2.65×1062.65\times10^6 J/ΨJ/\Psi and 2.40×1062.40\times10^6 PP-wave charmonium events per year can be obtained; and 1.01×1051.01\times10^5 BcB_c, 9.11×1049.11\times10^4 BcB^*_c and 3.16×1043.16\times10^4 PP-wave (cbˉ)(c\bar{b})-quarkonium events per year can be obtained. Main theoretical uncertainties have also been discussed. By adding the uncertainties caused by the quark masses in quadrature, we obtain ΓW+(ccˉ)+csˉ=524.8258.4+396.3\Gamma_{W^+\to (c\bar{c})+c\bar{s}} =524.8^{+396.3}_{-258.4} KeV, ΓW+(cbˉ)+bsˉ=13.53.29+4.73\Gamma_{W^+\to (c\bar{b})+b\bar{s}} =13.5^{+4.73}_{-3.29} KeV, ΓW+(cbˉ)+ccˉ=1.740.73+1.98\Gamma_{W^+\to (c\bar{b})+c\bar{c}}= 1.74^{+1.98}_{-0.73} KeV and ΓW+(bbˉ)+cbˉ=38.69.69+13.4\Gamma_{W^+\to (b\bar{b})+c\bar{b}}= 38.6^{+13.4}_{-9.69} eV.Comment: 24 pages, 12 figures. References updated. To be published in Phys.Rev. D. To match the published versio

    An Empirical Study of Catastrophic Forgetting in Large Language Models During Continual Fine-tuning

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    Catastrophic forgetting (CF) is a phenomenon that occurs in machine learning when a model forgets previously learned information as it learns new information. As large language models (LLMs) have shown excellent performance, it is interesting to uncover whether CF exists in the continual fine-tuning of LLMs. In this study, we empirically evaluate the forgetting phenomenon in LLMs' knowledge, from the perspectives of domain knowledge, reasoning, and reading comprehension. The experiments demonstrate that catastrophic forgetting is generally observed in LLMs ranging from 1b to 7b. Furthermore, as the scale increases, the severity of forgetting also intensifies. Comparing the decoder-only model BLOOMZ with the encoder-decoder model mT0, BLOOMZ suffers less forgetting and maintains more knowledge. We also observe that LLMs can mitigate language bias (e.g. gender bias) during continual fine-tuning. Moreover, we find that ALPACA can maintain more knowledge and capacity compared with LLAMA during the continual fine-tuning, which implies that general instruction tuning can help mitigate the forgetting phenomenon of LLMs in the further fine-tuning process
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