A set of global optical potential parameters, DA1p, for deuterons with the 1p-shell nuclei is obtained by simultaneously fitting 67 sets of experimental data of deuteron elastic scattering from \nuc{6}{Li}, \nuc{9}{Be}, \nuc{10}{B}, \nuc{11}{B}, \nuc{12}{C}, \nuc{13}{C}, \nuc{14}{N}, \nuc{16}{O} and \nuc{18}{O} with incident energies between 5.25 and 170 MeV. DA1p improves the description of the deuteron elastic scattering from the 1p-shell nuclei with respect to the existing systematic deuteron potentials and can give satisfactory reproduction to the experimental data with radiative nuclei such as \nuc{9}{Li}, \nuc{10}{Be}, \nuc{14}{C} and \nuc{14}{O}.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
Using AdS/CFT correspondence, we find that a massless quark moving at the speed of light v=1, in arbitrary direction, through a strongly coupled N=4 super Yang-Mills (SYM) vacuum at T=0, in the presence of strong magnetic field B, loses its energy at a rate linearly dependent on B, i.e., dtdE=−6πλB. We also show that a heavy quark of mass M=0 moving at near the speed of light v2=v∗2=1−B4π2T2≃1, in arbitrary direction, through a strongly coupled N=4 SYM plasma at finite temperature T=0, in the presence of strong magnetic field B≫T2, loses its energy at a rate linearly dependent on B, i.e., dtdE=−6πλBv∗2≃−6πλB. Moreover, we argue that, in the strong magnetic field B≫T2 (IR) regime, N=4 SYM and adjoint QCD theories (when the adjoint QCD theory has four flavors of Weyl fermions and is at its conformal IR fixed point λ=λ∗) have the same microscopic degrees of freedom (i.e., gluons and lowest Landau levels of Weyl fermions) even though they have quite different microscopic degrees of freedom in the UV when we consider higher Landau levels. Therefore, in the strong magnetic field B≫T2 (IR) regime, the thermodynamic and hydrodynamic properties of N=4 SYM and adjoint QCD plasmas, as well as the rates of energy loss of a quark moving through the plasmas, should be the same.
Comments:
6 pages; v2: a minor change to the title, explanation about the massless limit in the vacuum (without changing the conclusion) added, references added; v3: the equivalence between N=4 SYM and adjoint QCD in strong magnetic field discussed, published version in Rapid Communications PRD
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
The axial couplings of the low lying baryons are evaluated using a total of five ensembles of dynamical twisted mass fermion gauge configurations. The simulations are performed using the Iwasaki gauge action and two degenerate flavors of light quarks, and a strange and a charm quark fixed to approximately their physical values at two values of the coupling constant. The lattice spacings, determined using the nucleon mass, are a=0.082 fm and a=0.065 fm and the simulations cover a pion mass in the range of about 210 MeV to 430 MeV. We study the dependence of the axial couplings on the pion mass in the range of about 210 MeV to 430 MeV as well as the SU(3) breaking effects as we decrease the light quark mass towards its physical value.
Comments:
34 pages, 17 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
We have calculated the quenching parameter, q^ in a model-independent way using the gauge-gravity duality. In earlier calculations, the geometry in the gravity side at finite temperature was usually taken as the pure AdS blackhole metric for which the dual gauge theory becomes conformally invariant unlike QCD. Therefore we use a metric which incorporates the fundamental quarks by embedding the coincident D7 branes in the Klebanov-Tseytlin background and a finite temperature is switched on by inserting a black hole into the background, known as OKS-BH metric. Further inclusion of an additional UV cap to the metric prepares the dual gauge theory to run similar to thermal QCD. Moreover q^ is usually defined in the literature from the Glauber-model perturbative QCD evaluation of the Wilson loop, which has no reasons to hold if the coupling is large and is thus against the main idea of gauge-gravity duality. Thus we use an appropriate definition of q^: q^L−=1/L2, where L is the separation for which the Wilson loop is equal to some specific value. The above two refinements cause q^ to vary with the temperature as T4 always and to depend linearly on the light-cone time L− with an additional (1/L−) correction term in the short-distance limit whereas in the long-distance limit, it depends only linearly on L− with no correction term. These observations agree with other holographic calculations directly or indirectly.
Comments:
16 pages
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)