Calculations of the cross sections of inelastic electron scattering (e,e′) on a nucleus in the multi-keV energy range strongly depend on the description of the screening of the nuclear Coulomb ...potential as well as on the deformation of the wave functions of the incoming and outgoing electron in the vicinity of the nucleus. These cross sections are evaluated at values lower than 10−30cm2, which vary by several orders of magnitude according to the models. Experimental measurements would be required to constrain the models but it is a real challenge to measure such low cross sections. In this study, we demonstrate that inelastic electron scattering is the main nuclear excitation mechanism in a 181Ta target irradiated with a new intense 10–30 keV electron beam produced with a biased laser plasma. Calculations show that, through the detection of conversion electrons, it should be possible to measure the nuclear excitation yields. The effect of electron-beam heating and of plasma deposition on the tantalum target are quantified, thus allowing the dimensioning of a possible experimental configuration to study (e,e′) processes in this range of energy for the first time. (APS)
A
bstract
We compute the scattering amplitude for classical black-hole scattering to third order in the Post-Minkowskian expansion, keeping all terms needed to derive the scattering angle to that ...order from the eikonal formalism. Our results confirm a conjectured relation between the real and imaginary parts of the amplitude by Di Vecchia, Heissenberg, Russo, and Veneziano, and are in agreement with a recent computation by Damour based on radiation reaction in general relativity.
A
bstract
In this work, we use an extension of the quantization condition, given in ref.
1
, to numerically explore the finite-volume spectrum of three relativistic particles, in the case that ...two-particle subsets are either resonant or bound. The original form of the relativistic three-particle quantization condition was derived under a technical assumption on the two- particle K matrix that required the absence of two-particle bound states or narrow two- particle resonances. Here we describe how this restriction can be lifted in a simple way using the freedom in the definition of the K-matrix-like quantity that enters the quantization condition. With this in hand, we extend previous numerical studies of the quantization condition to explore the finite-volume signature for a variety of two- and three-particle interactions. We determine the spectrum for parameters such that the system contains both dimers (two-particle bound states) and one or more trimers (in which all three particles are bound), and also for cases where the two-particle subchannel is resonant. We also show how the quantization condition provides a tool for determining infinite-volume dimer- particle scattering amplitudes for energies below the dimer breakup. We illustrate this for a series of examples, including one that parallels physical deuteron-nucleon scattering. All calculations presented here are restricted to the case of three identical scalar particles.
A
bstract
In this third paper of a series dedicated to a dispersive treatment of the hadronic light-by-light (HLbL) tensor, we derive a partial-wave formulation for two-pion intermediate states in ...the HLbL contribution to the anomalous magnetic moment of the muon (
g
− 2)
μ
, including a detailed discussion of the unitarity relation for arbitrary partial waves. We show that obtaining a final expression free from unphysical helicity partial waves is a subtle issue, which we thoroughly clarify. As a by-product, we obtain a set of sum rules that could be used to constrain future calculations of
γ
∗
γ
∗
→
ππ
. We validate the formalism extensively using the pion-box contribution, defined by two-pion intermediate states with a pion-pole left-hand cut, and demonstrate how the full known result is reproduced when resumming the partial waves. Using dispersive fits to high-statistics data for the pion vector form factor, we provide an evaluation of the full pion box,
a
μ
π
− box
= − 15.9(2) × 10
− 11
. As an application of the partial-wave formalism, we present a first calculation of
ππ
-rescattering effects in HLbL scattering, with
γ
∗
γ
∗
→
ππ
helicity partial waves constructed dispersively using
ππ
phase shifts derived from the inverse-amplitude method. In this way, the isospin-0 part of our calculation can be interpreted as the contribution of the
f
0
(500) to HLbL scattering in (
g
− 2)
μ
. We argue that the contribution due to charged-pion rescattering implements corrections related to the corresponding pion polarizability and show that these are moderate. Our final result for the sum of pion-box contribution and its
S
-wave rescattering corrections reads
a
μ
π
‐ box
+
a
μ
,
J
= 0
ππ
,
π
‐ pole LHC
= − 24(1) × 10
− 11
.
Graphitic carbon nitride (g-C 3 N 4 ), possessing high thermal and chemical stability, non-toxicity, facile synthesis, and low band gap energy is a promising candidate for photocatalytic ...applications. In this study, bulk and exfoliated g-C 3 N 4 were synthesised from different precursors (melamine and urea). Moreover, the surface of bulk g-C 3 N 4 and exfoliated g-C 3 N 4 was modified with graphene (0.5 wt% and 1 wt%) aiming to obtain a prolonged carrier lifetime. The effect of g-C 3 N 4 synthesis from various precursors and the influence of graphene content on the photocatalytic activity during the degradation of a water–methanol mixture under UVC irradiation were examined, in comparison to commercial P25. Hydrogen, methane and carbon monoxide were the decomposition products; hydrogen was the main product of decomposition, whereas CH 4 and CO resulting from the reduction of CO 2 were generated in a significantly smaller amount. All the produced photocatalysts, whether pure or modified with graphene, exhibited higher activity than the commercial photocatalyst P25.
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