Charmed semileptonics with twisted-mass valence quarks
Julien Frison, Gregorio Herdoiza, Carlos Pena, Jose Angel Romero, Javier Ugarrio
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9 pages, 7 figures; Proceedings of the 38th International Symposium on Lattice Field Theory - Lattice 2021 26-30 July 2021, Zoom/Gather@MIT (USA) - PoS(LATTICE2021)320
Our charm program uses a mixed action with twisted-mass valence quarks over non-perturbatively improved Wilson sea quarks, in order to study various quantities in a relativistic and manifestly local framework of full QCD. The sea sector consists of $N_\mathrm{f}=2+1$ ensembles generated by the CLS initiative. Taking advantage of open boundary conditions, this allows access to fine ensembles without topological freezing. Here we focus in particular on our current progress on $D\to Kνl$ and $D\to πνl$ semileptonics. Those are first and foremost useful for the computation of the CKM matrix elements $|V_{cs}|$ and $|V_{cd}|$. We show that all discretisation effects seem to be reasonably under control with this choice of action, in particular those related to hypercubic lattice artefacts. Eventually, we obtain preliminary results of the form factors as a very smooth curve on the whole range of momentum transfer, and in particular the signal at zero $q^2$ appears to have the potential to be competitive with earlier published results.
Non-Standard Physics in Leptonic and Semileptonic Decays of Charmed Mesons
最近对D_s -> 1 nu的分支分数的测量结果与标准模型的预期不一致,标准模型的预期依赖于格点量子色动力学对$f_{D_s}$的计算。本文使用最近的初步测量从CLEO和一个新的初步格QCD结果从这次会议上更新的差异的意义。“f_{D_s}之谜”现在是3.5西格玛,西格玛主要来自实验的统计不确定性。新的物理方案,可以解决这个难题,也将导致非标准振幅介导的半轻子衰变D -> K l nu。本文展示了新的振幅进入微分速率和概述格点量子色动力学计算需要面对最近和即将到来的测量。
Puzzles in charmed baryon semileptonic decays with $SU(3)_F$ flavor symmetry and lattice inputs
School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, UCAS(杭州高等研究院基础物理与数学学院);Institute of Theoretical Physics, UCAS(理论物理研究所);University of Chinese Academy of Sciences(中国科学院大学)
Semileptonic B to D decays at nonzero recoil with 2+1 flavors of improved staggered quarks. An update
费米实验室晶格和MILC合作正在完成一个关于MILC(2+1)风格asqtad合奏的综合性重光物理计划,晶格间距小至0.045 fm,光与奇异夸克质量比低至1/20。我们使用费米实验室的三叶草行动的重价夸克和asqtad行动的轻价夸克的解释。该计划的中心目标是提供CKM矩阵的酉性的更精确的测试。我们目前的初步结果的程序的一部分,即在非零反冲的半轻子衰变B -> D l nu的分析。
Charmed Baryon Spectroscopy from Lattice QCD with $N_f=2+1+1$ flavors
本文给出了用N_f=2+1+1 $ dynamical quarks. The calculation uses a relativistic heavy-quark action for the valence charm quark, clover-Wilson fermions for the valence light quarks and HISQ sea quarks. The spectrum is calculated with a lightest pion mass around 220 MeV and two lattice spacings ($ a \sim 0.12 $ fm and 0.09 fm) are used to extrapolate to continuum limit. Our preliminary results are consistent with the currently measured baryon spectrum, except for the isospin-averaged $ J=1/2 $ $ σ_{cc} $ which is approximately $ 2 σ $ above the SELEX observed value. We predict the yet-to-be-discovered d…
Form factors for B and B_s semileptonic decays with NRQCD/HISQ quarks
本文讨论了半轻子衰变B -> pi lv,B_s -> K lv和B -> K ll的形状因子的计算方法.我们用NRQCD重夸克和HISQ轻价夸克模拟了MILC 2+1动力学对称组态.在动量传递的范围内计算形状因子,以确定其形状并提取|V_ub|。此外,我们还计算了这些形状因子与非物理衰变B_s -> eta_s的比值。我们正在研究将这些精确确定的比值与未来使用HISQ b夸克计算B_s ->eta_s相结合的可能性,以产生误差显著减少的形状因子。
$D$-meson semileptonic form factors at zero momentum transfer in (2+1+1)-flavor lattice QCD
我们提出了一个计算的$D\to K \ell ν$和$D\toπ\ell ν$半轻子形状因子在$q^2=0$,这使得确定的CKM矩阵元素$\lvert{V_{cs}}\rvert$和$\lvert{V_{cd}}\rvert$,分别。我们使用的规范场配置产生的MILC合作与四种口味的高度改进的交错(HISQ)夸克,分析几个合奏,包括那些物理介子质量和近似的晶格间距范围从0.12~fm到0.042~fm。对于价夸克,我们也使用了HISQ作用量。我们采用扭曲边界条件直接计算零动量转移时的形状因子。我们使用重轻介子手征微扰理论修正了高能π介子和K介子,并补充了描述晶格间距依赖性的项,得到了物理点和连续极限的初步结果.
Semileptonic B Decays with Nf=2+1 Dynamical Quarks
本文用NRQCD重夸克和Asqtad轻夸克研究了MILC动力学组态上的半轻子、B -> pi 1、nu衰变。我们研究的轻价夸克质量在m_s和m_s/8之间。初步的简单的线性手性外推已经进行了形状因子f_para和f_perp在固定的E_pi。然后将形状因子f+(q^2)和f0(q^2)的手性外推结果拟合到Becirevic-Kaidalov(BK)模型。CKM矩阵元素的初步估计|V_{ub}|基于CLEO合作组最近发表的B排他半轻子衰变的分支分数,
Istituto Nazionale di Fisica Nucleare, Sezione di Bari(意大利国家核物理研究所巴里分部);Dipartimento Interateneo di Fisica ”Michelangelo Merlin”, Università degli Studi di Bari(巴里大学米开朗基罗·梅林跨大学物理系)
Semileptonic decays of K and D mesons in 2+1 flavor QCD
实验测量的半轻子衰变速率K -> pi l nu和D -> K(pi)l nu可以与相关形状因子的晶格计算相结合,以精确地提取CKM矩阵元|V_{us}|和|V_{cs(d)}|.本文报道了费米实验室用粲夸克和交错轻夸克在2+1味asqtad交错MILC系综上计算形状因子的情况。通过与CLEO数据的比较,对D -> pil nu形状因子的数据分析提供了对我们的方法的非平凡测试。本文讨论了用HISQ价夸克计算K -> pi l nu形状因子f_+^{K pi}(0)的方法,并描述了我们方法的检验。
Singly and Doubly Charmed J=1/2 Baryon Spectrum from Lattice QCD
We compute the masses of the singly and doubly charmed baryons in full QCD using the relativistic Fermilab action for the charm quark. For the light quarks we use domain-wall fermions in the valence sector and improved Kogut-Susskind sea quarks. We use the low-lying charmonium spectrum to tune our heavy-quark action and as a guide to understanding the discretization errors associated with the heavy quark. Our results are in good agreement with experiment within our systematics. For the Ξ_{cc}, we find the isospin-averaged mass to be M_{Ξ_{cc}} = 3665 +/- 17 +/- 14 +0 -78 MeV; the three given u…