High Energy Physics  Lattice
New submissions
[ showing up to 2000 entries per page: fewer  more ]
New submissions for Thu, 23 Nov 17
 [1] arXiv:1711.08085 [pdf, ps, other]

Title: $B_s \to K \ellν$ form factors with 2+1 flavorsAuthors: Fermilab Lattice, MILC Collaborations: Yuzhi Liu (1), Jon A. Bailey (2), A. Bazavov (3), C. Bernard (4), C.M. Bouchard (5), C. DeTar (6), Daping Du (7), A.X. ElKhadra (8,9), E.D. Freeland (10), E. Gámiz (11), Z. Gelzer (8,12), Steven Gottlieb (1), U.M. Heller (13), A.S. Kronfeld (9,14), J. Laiho (7), P.B. Mackenzie (9), Y. Meurice (12), E.T. Neil (15,16), J.N. Simone (9), R. Sugar (17), D. Toussaint (18), R.S. Van de Water (9), Ran Zhou (9) ((1) Indiana University, (2) Seoul National University, (3) Michigan State University, (4) Washington University, (5) University of Glasgow, (6) University of Utah, (7) Syracuse University, (8) University of Illinois, (9) Fermilab, (10) School of the Art Institute of Chicago, (11) Universidad de Granada, (12) University of Iowa, (13) American Physical Society, (14) Technische Universität München, (15) University of Colorado, (16) Brookhaven National Laboratory, (17) University of California, Santa Barbara, (18) University of Arizona)Comments: 8 pages, 6 figures, to appear in the Proceedings of Lattice 2017, June 1824, Granada, SpainSubjects: High Energy Physics  Lattice (heplat)
Using the MILC 2+1 flavor asqtad quark action ensembles, we are calculating the form factors $f_0$ and $f_+$ for the semileptonic $B_s \rightarrow K \ell\nu$ decay. A total of six ensembles with lattice spacing from $\approx0.12$ to 0.06 fm are being used. At the coarsest and finest lattice spacings, the light quark mass $m'_l$ is onetenth the strange quark mass $m'_s$. At the intermediate lattice spacing, the ratio $m'_l/m'_s$ ranges from 0.05 to 0.2. The valence $b$ quark is treated using the SheikholeslamiWohlert Wilsonclover action with the Fermilab interpretation. The other valence quarks use the asqtad action. When combined with (future) measurements from the LHCb and Belle II experiments, these calculations will provide an alternate determination of the CKM matrix element $V_{ub}$.
 [2] arXiv:1711.08121 [pdf, other]

Title: Calculation of fermionic Green functions with Grassmann higherorder tensor renormalization groupSubjects: High Energy Physics  Lattice (heplat)
We develop calculational method for fermionic Green functions in the framework of Grassmann higherorder tensor renormalization group. The validity of the method is tested by applying it to threedimensional free Wilson fermion system. We compare the numerical results for chiral condensate and twopoint correlation functions with the exact ones obtained by analytical methods.
Crosslists for Thu, 23 Nov 17
 [3] arXiv:1711.07858 (crosslist from hepph) [pdf, other]

Title: Gaussianweighted Parton QuasidistributionAuthors: JiunnWei Chen, Tomomi Ishikawa, Luchang Jin, HueyWen Lin, Andreas Schäfer, YiBo Yang, JianHui Zhang, Yong ZhaoComments: 9 pages, 3 figuresSubjects: High Energy Physics  Phenomenology (hepph); High Energy Physics  Lattice (heplat)
We propose a revised definition of quasidistributions within the framework of largemomentum effective theory (LaMET) that improves convergence towards the largemomentum limit. Since the definition of quasidistributions is not unique, each choice goes along with a specific matching function, we can use this freedom to optimize convergence towards the largemomentum limit. As an illustration, we study quasidistributions with a Gaussian weighting factor that naturally suppresses longrange correlations, which are plagued by artifacts. This choice has the advantage that the matching functions can be trivially obtained from the known ones. We apply the Gaussian weighting to the previously published results for the nonperturbatively renormalized unpolarized quark distribution, and find that the unphysical oscillatory behavior is significantly reduced.
 [4] arXiv:1711.08062 (crosslist from condmat.meshall) [pdf, other]

Title: Coupling magnetoelastic Lagrangians to spin transfer torque sourcesComments: 6 pages, LaTeX2e, 3 figuresSubjects: Mesoscale and Nanoscale Physics (condmat.meshall); Materials Science (condmat.mtrlsci); High Energy Physics  Lattice (heplat)
The consequences of coupling magnetic and elastic degrees of freedom, where spins and deformations are carried by pointlike objects subject to local interactions, are studied, theoretically and by detailed numerical simulations. From the constrained Lagrangians we derive consistent equations of motion for the coupled dynamical variables. In order to probe the dynamics of such a system, we consider external perturbations, such as spin transfer torques for the magnetic part, and homogeneous stresses for the elastic part, associated to their corresponding damping. This approach is applied to the study of ultrafast switching processes in antiferromagnetic systems, which have recently attracted attention as candidates for antiferromagnetic spintronic devices. Our strategy is then checked in simple, but instructive, situations. We carried out numerical experiments to study, in particular, how the magnetostrictive coupling and external stresses affect the nature of the switching processes in a prototype antiferromagnetic material.
 [5] arXiv:1711.08088 (crosslist from hepph) [pdf, ps, other]

Title: Hadron tomography by generalized distribution amplitudes in pionpair production process $γ^* γ\rightarrow π^0 π^0 $ and gravitational form factors for pionComments: 26 pages, 21 figuresSubjects: High Energy Physics  Phenomenology (hepph); High Energy Physics  Experiment (hepex); High Energy Physics  Lattice (heplat); Nuclear Theory (nuclth)
Hadron tomography can be investigated by threedimensional structure functions such as generalized parton distributions (GPDs), transversemomentumdependent parton distributions, and generalized distribution amplitudes (GDAs). Here, we extract the GDAs, which are $s$$t$ crossed quantities of the GPDs, from crosssection measurements of hadronpair production process $\gamma^* \gamma \rightarrow \pi^0 \pi^0$ at KEKB. This work is the first attempt to obtain the GDAs from the actual experimental data. The GDAs are expressed by a number of parameters and they are determined from the data of $\gamma^* \gamma \rightarrow \pi^0 \pi^0$ by including intermediate scalar and tensormeson contributions to the cross section. Our results indicate that the dependence of partonmomentum fraction $z$ in the GDAs is close to the asymptotic one. The timelike gravitational form factors $\Theta_1$ and $\Theta_2$ are obtained from our GDAs, and they are converted to the spacelike ones by the dispersion relation. From the spacelike $\Theta_1$ and $\Theta_2$, gravitational densities of the pion are calculated. Then, we obtained the mass (energy) radius and the mechanical (pressure and shear force) radius from $\Theta_2$ and $\Theta_1$, respectively. They are calculated as $\sqrt {\langle r^2 \rangle_{\text{mass}}} =0.56 \sim 0.69$ fm, whereas the mechanical radius is larger $\sqrt {\langle r^2 \rangle_{\text{mech}}} =1.45 \sim 1.56$ fm. This is the first report on the gravitational radius of a hadron from actual experimental measurements. It is interesting to find the possibility that the gravitational mass and mechanical radii could be different from the experimental charge radius $\sqrt {\langle r^2 \rangle_{\text{charge}}} =0.672 \pm 0.008$ fm for the charged pion. There is a byproduct from our analysis that $f_0 (980)$ is not likely to be a $q\bar q$type meson in comparison with the KEKB data.
Replacements for Thu, 23 Nov 17
 [6] arXiv:1708.01216 (replaced) [pdf, ps, other]

Title: Improved thermodynamics of SU(2) gauge theoryComments: 32 pages, 22 figures. Source files of 20 figures (format agr of the program xmgrace) included in the submission as "ancillary files" from which raw data can be extracted. In this third version we removed 4 figures and we modified substantially Secs. 2.2, 3.3 and 4Subjects: High Energy Physics  Lattice (heplat)
 [7] arXiv:1710.08066 (replaced) [pdf, ps, other]

Title: Comparison of different source calculations in twonucleon channel at large quark massComments: 8 pages, 7 figures, Proceedings of the 35th International Symposium on Lattice Field Theory (Lattice 2017), June 1924, 2017, Granada, SpainSubjects: High Energy Physics  Lattice (heplat)
[ showing up to 2000 entries per page: fewer  more ]
Disable MathJax (What is MathJax?)