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"Constantinou, M."
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Measurement of the neutron charge radius and the role of its constituents
The neutron is a cornerstone in our depiction of the visible universe. Despite the neutron zero-net electric charge, the asymmetric distribution of the positively- (up) and negatively-charged (down) quarks, a result of the complex quark-gluon dynamics, lead to a negative value for its squared charge radius,
⟨
r
n
2
⟩
. The precise measurement of the neutron’s charge radius thus emerges as an essential part of unraveling its structure. Here we report on a
⟨
r
n
2
⟩
measurement, based on the extraction of the neutron electric form factor,
G
E
n
, at low four-momentum transfer squared (
Q
2
) by exploiting the long known connection between the
N
→ Δ quadrupole transitions and the neutron electric form factor. Our result,
⟨
r
n
2
⟩
=
−
0.110
±
0.008
(
fm
2
)
, addresses long standing unresolved discrepancies in the
⟨
r
n
2
⟩
determination. The dynamics of the strong nuclear force can be viewed through the precise picture of the neutron’s constituent distributions that result into the non-zero
⟨
r
n
2
⟩
value.
The charge radius of nucleons provides information about their structure. Here the authors present a method, based values of neutron electric form factors, to determine the charge radius of the neutron and provide information on improving the uncertainty of neutron charge radius measurements
Journal Article
Transprofessional diplomacy
\"Diplomacy is no longer restricted to a single vocation nor implemented exclusively through interaction amongst official representatives. In exploring the challenges that these transformations produce, this work surveys firstly, the genealogy of diplomacy as a profession, tracing how it changed from a civic duty into a vocation requiring training and the acquisition of specific knowledge and skills. Secondly, using the lens of the sociology of professions, the development of diplomacy as a distinctive profession is examined, including its importance for the consolidation of the power of modern nation-states. Thirdly, it examines how the landscape of professional diplomacy is being diversified and, we argue, enriched by a series of non-state actors, with their corresponding professionals, transforming the phenomenology of contemporary diplomacy. Rather than seeing this pluralization of diplomatic actors in negative terms as the deprofessionalization of diplomacy, we frame these trends as transprofessionalization, that is, as a productive development that reflects the expanded diplomatic space and the intensified pace of global interconnections and networks, and the new possibilities they unleash for practising diplomacy in different milieus.\" Cover page 4.
Book
Open database for GPD analyses
This article summarizes the main ideas behind creating an open database proposed for use in the exploration of generalized parton distributions (GPDs). This lightweight database is well suited for GPD phenomenology and is designed to store both experimental and lattice-QCD data. It can also aid in benchmarking GPD-related developments, such as GPD models. The database utilizes a new data format based on the YAML serialization language, enabling the storage of essential information for modern analyses, such as replica values. It includes interfaces for both Python and C++, allowing straightforward integration with analysis codes.
Journal Article
The plasma bioavailability of nitrate and betanin from Beta vulgaris rubra in humans
Purpose To evaluate the plasma bioavailability of betanin and nitric oxide (NOx) after consuming beetroot juice (BTJ) and whole beetroot (BF). BTJ and BF were also analysed for antioxidant capacity, polyphenol content (TPC) and betalain content. Methods Ten healthy males consumed either 250 ml of BTJ, 300 g of BF or a placebo drink, in a randomised, crossover design. Venous plasma samples were collected pre (baseline), 1, 2, 3, 5 and 8 h post-ingestion. Betanin content in BTJ, BF and plasma was analysed with reverse-phase high-performance liquid chromatography (HPLC) and mass spectrometry detection (LCMS). Antioxidant capacity was estimated using the Trolox equivalent antioxidant capacity (TEAC) and polyphenol content using Folin–Ciocalteu colorimetric methods [gallic acid equivalents (GAE)] and betalain content spectrophotometrically. Results TEAC was 11.4 ± 0.2 mmol/L for BTJ and 3.4 ± 0.4 μmol/g for BF. Both BTJ and BF contained a number of polyphenols (1606.9 ± 151 mg/GAE/L and 1.67 ± 0.1 mg/GAE/g, respectively), betacyanins (68.2 ± 0.4 mg/betanin equivalents/L and 19.6 ± 0.6 mg/betanin equivalents/100 g, respectively) and betaxanthins (41.7 ± 0.7 mg/indicaxanthin equivalents/L and 7.5 ± 0.2 mg/indicaxanthin equivalents/100 g, respectively). Despite high betanin contents in both BTJ (~194 mg) and BF (~66 mg), betanin could not be detected in the plasma at any time point post-ingestion. Plasma NOx was elevated above baseline for 8 h after consuming BTJ and 5 h after BF (P < 0.05). Conclusions These data reveal that BTJ and BF are rich in phytonutrients and may provide a useful means of increasing plasma NOx bioavailability. However, betanin, the major betalain in beetroot, showed poor bioavailability in plasma
Journal Article
Charge radii of the nucleon from its flavor dependent Dirac form factors
We have determined the proton and the neutron charge radii from a global analysis of the proton and the neutron elastic form factors, after first performing a flavor decomposition of these form factors under charge symmetry in the light cone frame formulation. We then extracted the transverse mean-square radii of the flavor dependent quark distributions. In turn, these are related in a model-independent way to the proton and neutron charge radii but allow us to take into account motion effects of the recoiling nucleon for data at finite but high momentum transfer. In the proton case we find
⟨
r
p
⟩
=
0.852
±
0
.
002
(
stat
.
)
±
0
.
009
(
syst
.
)
(
fm
)
, consistent with the proton charge radius obtained from muonic hydrogen spectroscopy [
1
,
2
]. The current method improves on the precision of the
⟨
r
p
⟩
extraction based on the form factor measurements. Furthermore, we find no discrepancy in the
⟨
r
p
⟩
determination among the different electron scattering measurements, all of which, utilizing the current method of extraction, result in a value that is consistent with the smallest
⟨
r
p
⟩
extraction from the electron scattering measurements [
3
]. Concerning the neutron case, past results relied solely on the neutron-electron scattering length measurements, which suffer from an underestimation of underlying systematic uncertainties inherent to the extraction technique. Utilizing the present method we have performed the first extraction of the neutron charge radius based on nucleon form factor data, and we find
⟨
r
n
2
⟩
=
-
0.122
±
0
.
004
(
stat
.
)
±
0
.
010
(
syst
.
)
(
fm
2
)
.
Journal Article
Exploring baryon resonances with transition generalized parton distributions: status and perspectives
QCD gives rise to a rich spectrum of excited baryon states. Understanding their internal structure is important for many areas of nuclear physics, such as nuclear forces, dense matter, and neutrino-nucleus interactions. Generalized parton distributions (GPDs) are an established tool for characterizing the QCD structure of the ground-state nucleon. They are used to create 3D tomographic images of the quark/gluon structure and quantify the mechanical properties such as the distribution of mass, angular momentum, and forces in the system. Transition GPDs extend these concepts to
N
→
N
∗
transitions and can be used to characterize the 3D structure and mechanical properties of baryon resonances. They can be probed in high-momentum-transfer exclusive electroproduction processes with resonance transitions
e
+
N
→
e
′
+
M
+
N
∗
, such as deeply-virtual Compton scattering (
M
=
γ
) or meson production (
M
=
π
,
K
, etc.), and in related photon/hadron-induced processes. This White Paper describes a research program aiming to explore baryon resonance structure with transition GPDs. This includes the properties and interpretation of the transition GPDs, theoretical methods for structures and processes, first experimental results from JLab 12 GeV, future measurements with existing and planned facilities (JLab detector and energy upgrades, COMPASS/AMBER, EIC, EicC, J-PARC, LHC ultraperipheral collisions), and the theoretical and experimental developments needed to realize this program.
Journal Article
Imagining Ro: On the social life of islets and the politics of islandography
This article engages the challenge of island history as caught in between national historiography and local life stories. It focuses on Ro, a Greek islet bordering Turkey that has been imagined and idealized as a space of national resistance and resilience. The article unpacks the grand national narrative that has been developed with regard to the heroic life story of a solitary woman living on the island. It utilizes local counter-narratives as well as the life stories of other solitary individuals who have periodically lived on the island. To that extent, the article aims, on the one hand, to sensitize as to the politics of islandography and, on the other, to highlight the importance of social history in challenging hegemonic or colonial narratives as well as reimagining island space.
Journal Article