 Publication Date:
 NSFPAR ID:
 10251130
 Journal Name:
 Journal of High Energy Physics
 Volume:
 2021
 Issue:
 5
 ISSN:
 10298479
 Sponsoring Org:
 National Science Foundation
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Abstract Scattering of high energy particles from nucleons probes their structure, as was done in the experiments that established the nonzero size of the proton using electron beams 1 . The use of charged leptons as scattering probes enables measuring the distribution of electric charges, which is encoded in the vector form factors of the nucleon 2 . Scattering weakly interacting neutrinos gives the opportunity to measure both vector and axial vector form factors of the nucleon, providing an additional, complementary probe of their structure. The nucleon transition axial form factor, F A , can be measured from neutrino scattering from free nucleons, ν μ n → μ − p and $${\bar{\nu }}_{\mu }p\to {\mu }^{+}n$$ ν ¯ μ p → μ + n , as a function of the negative fourmomentum transfer squared ( Q 2 ). Up to now, F A ( Q 2 ) has been extracted from the bound nucleons in neutrino–deuterium scattering 3–9 , which requires uncertain nuclear corrections 10 . Here we report the first highstatistics measurement, to our knowledge, of the $${\bar{\nu }}_{\mu }\,p\to {\mu }^{+}n$$ ν ¯ μ p → μ + n crosssection from the hydrogen atom, using the plastic scintillatormore »

Meila, Marina ; Zhang, Tong (Ed.)In the Correlation Clustering problem, we are given a complete weighted graph $G$ with its edges labeled as “similar" and “dissimilar" by a noisy binary classifier. For a clustering $\mathcal{C}$ of graph $G$, a similar edge is in disagreement with $\mathcal{C}$, if its endpoints belong to distinct clusters; and a dissimilar edge is in disagreement with $\mathcal{C}$ if its endpoints belong to the same cluster. The disagreements vector, $\mathbf{disagree}$, is a vector indexed by the vertices of $G$ such that the $v$th coordinate $\mathbf{disagree}_v$ equals the weight of all disagreeing edges incident on $v$. The goal is to produce a clustering that minimizes the $\ell_p$ norm of the disagreements vector for $p\geq 1$. We study the $\ell_p$ objective in Correlation Clustering under the following assumption: Every similar edge has weight in $[\alpha\mathbf{w},\mathbf{w}]$ and every dissimilar edge has weight at least $\alpha\mathbf{w}$ (where $\alpha \leq 1$ and $\mathbf{w}>0$ is a scaling parameter). We give an $O\left((\frac{1}{\alpha})^{\frac{1}{2}\frac{1}{2p}}\cdot \log\frac{1}{\alpha}\right)$ approximation algorithm for this problem. Furthermore, we show an almost matching convex programming integrality gap.

A bstract We analyze the New Physics sensitivity of a recently proposed method to measure the CPviolating $$ \mathcal{B} $$ B ( K S → μ + μ − ) ℓ =0 decay rate using K S − K L interference. We present our findings both in a modelindependent EFT approach as well as within several simple NP scenarios. We discuss the relation with associated observables, most notably $$ \mathcal{B} $$ B ( K L → π 0 $$ \nu \overline{\nu} $$ ν ν ¯ ). We find that simple NP models can significantly enhance $$ \mathcal{B} $$ B ( K S → μ + μ − ) ℓ =0 , making this mode a very promising probe of physics beyond the standard model in the kaon sector.

Abstract We conduct porescale simulations of twophase flow using the 2D Rothman–Keller colour gradient lattice Boltzmann method to study the effect of wettability on saturation at breakthrough (sweep) when the injected fluid first passes through the right boundary of the model. We performed a suite of 189 simulations in which a “red” fluid is injected at the left side of a 2D porous model that is initially saturated with a “blue” fluid spanning viscosity ratios $$M = \nu _\mathrm{r}/\nu _\mathrm{b} \in [0.001,100]$$ M = ν r / ν b ∈ [ 0.001 , 100 ] and wetting angles $$\theta _\mathrm{w} \in [ 0^\circ ,180^\circ ]$$ θ w ∈ [ 0 ∘ , 180 ∘ ] . As expected, at lowviscosity ratios $$M=\nu _\mathrm{r}/\nu _\mathrm{b} \ll 1$$ M = ν r / ν b ≪ 1 we observe viscous fingering in which narrow tendrils of the red fluid span the model, and for highviscosity ratios $$M \gg 1$$ M ≫ 1 , we observe stable displacement. The viscous finger morphology is affected by the wetting angle with a tendency for more rounded fingers when the injected fluid is wetting. However, rather than the expected result of increased saturation with increasing wettability,more »

Abstract We present the first unquenched latticeQCD calculation of the form factors for the decay
at nonzero recoil. Our analysis includes 15 MILC ensembles with$$B\rightarrow D^*\ell \nu $$ $B\to {D}^{\ast}\ell \nu $ flavors of asqtad sea quarks, with a strange quark mass close to its physical mass. The lattice spacings range from$$N_f=2+1$$ ${N}_{f}=2+1$ fm down to 0.045 fm, while the ratio between the light and the strangequark masses ranges from 0.05 to 0.4. The valence$$a\approx 0.15$$ $a\approx 0.15$b andc quarks are treated using the Wilsonclover action with the Fermilab interpretation, whereas the light sector employs asqtad staggered fermions. We extrapolate our results to the physical point in the continuum limit using rooted staggered heavylight meson chiral perturbation theory. Then we apply a modelindependent parametrization to extend the form factors to the full kinematic range. With this parametrization we perform a joint latticeQCD/experiment fit using several experimental datasets to determine the CKM matrix element . We obtain$$V_{cb}$$ ${V}_{\mathrm{cb}}$ . The first error is theoretical, the second comes from experiment and the last one includes electromagnetic and electroweak uncertainties, with an overall$$\left V_{cb}\right = (38.40 \pm 0.68_{\text {th}} \pm 0.34_{\text {exp}} \pm 0.18_{\text {EM}})\times 10^{3}$$ $\left({V}_{\mathrm{cb}}\right)=(38.40\pm 0.{68}_{\text{th}}\pm 0.{34}_{\text{exp}}\pm 0.{18}_{\text{EM}})\times {10}^{3}$ , which illustrates the tensions between the experimental data sets, and between theory and experiment. This result is inmore »$$\chi ^2\text {/dof} = 126/84$$ ${\chi}^{2}\text{/dof}=126/84$