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The Indigenous village of Bykovskiy is located 40 km from Tiksi, the administrative center of Bulunskiy District (Ulus), in the northern part of the Republic of Sakha (Yakutiya), Russia. Founded as a Soviet fishing cooperative, it became home to Indigenous Sakha, Evenkis, Evens, as well as to Russian settlers and political prisoners from the Baltic states. Post-Soviet transformations, coupled with escalating environmental change processes, has been altering the local economy and subsistence activities since the 1990s. Although our interlocutors directly observed and experienced such changes, they seemed to ignore the visible problem of severe coastal erosion that was destroying a local cemetery. This article is based on ethnographic fieldwork conducted in the study region in 2019, and combines approaches from the anthropology of climate change with reception and communication studies. It examines “ignorance” as a strategy of adaptation to multiple stressors under historically reproduced colonial structures of governance.

This introduction attempts to situate railroads, which have rarely been the object of ethnographic attention, within current debates of anthropology and related disciplines. While mobility is certainly one dimension of human-railroad entanglements, the introduction calls to explore political, social, material, and affective lives of railroads in Europe and Asia as well. Often, connections provided by railroads are precarious at best: enveloped in state and local politics, they appear to some as promise and to others as menace. Planning, construction, decay, and reconstruction constitute the temporal and material life cycle of these infrastructures. Attending to particular ethnographic and historical contexts, the introduction aims to demonstrate how railroads, these potent symbols of modernity, continue to be good to think with. The version of record is December 2020, though the actual publication date is May/June 202.

The town of Tiksi came into being in the 1930s, when the Soviet Union intensified its efforts to industrialize the Arctic. A critical element of that policy was to make the Northern Sea Route a viable Arctic shipping lane and Tiksi, located where the Lena River meets the Arctic Ocean, became an important transportation hub on that route. Post-Soviet transformations led to a rapid decline in population numbers and economic significance of the town, while climate change opened up new opportunities for shipping and mammoth tusk collecting. Today, the situation seems to have stabilized but the promises of a bright future pronounced in strategic papers by the government are yet to be realized. The article explores the socio-economic, infrastructural and environmental changes of recent decades in order to explore future development prospects for Tiksi. The infrastructural legacies of the Soviet past, combined with the environmental conditions of the region, result in the intertwined material dependencies of built and natural environments. Still, these material dependencies are neither straitjackets nor unchangeable. It is the interplay between global climate change, national policies, and local initiative that will challenge the material dependencies of the past and present.

This paper presents the results from fieldwork conducted in three focal areas of the “Nunataryuk” EU H2020 permafrost project: the Nordic Area (Greenland and Svalbard), the Beaufort Sea Area in Canada (Northwest Territories/ Inuvialuit Settlement Region and Gwich’in First Nation Traditional Territory) and Northeastern Siberia in Russia. The paper analyzes the entanglement between social and environmental change and presents a risk analysis framework, including the interconnected geo-physical & socio-cultural risks, with the aim to improve adaptation and mitigation strategies of local communities. Guided by a mixed-methods approach, the research outcomes are the result of field-based research, including focus groups, qualitative interviews, participant observation, community workshops – as well as a quantitative survey in three settlements (Qeqertarsuaq in Greenland, Aklavik in Canada and Longyearbyen on Svalbard).

A World Trimmed with Fur: Wild Things and the Natural Fringes of Qing Rule Jonathan Schlesinger (Stanford, CA: Stanford University Press, 2017), 288 pp. ISBN: 9780804799966Ethnic and Religious Minorities in Stalin’s Soviet Union: New Dimensions of Research Andrej Kotljarchuk and Olle Sundström, eds. (Stockholm: Elanders, 2017), 283 pp., paperback $27.00. ISBN: 978-91-7601-777-7.Kosmologiia i praktika sibirskogo shamanizma Elena V. Nam (Tomsk: Tomskii gosudarstvennyi universitet, 2017), 296 pp. ISBN: 978-5-7511-2521-9.Kul’tura i resursy. Opyt etnologicheskogo obsledovaniia sovremennogo polozheniia narodov Severnogo Sakhalina Dmitrii Funk, ed. (Moscow: “Demos,” 2015), 272 pp. ISBN 978-5-9904710-6-1.Maritime Hunting Culture of Chukotka: Traditions and Modern Practices Igor Krupnik and Rachel Mason, eds. (Anchorage, AK: National Park Service, Shared Beringian Heritage Program, 2016), 343 pp. ISBN: 9780990725251. Litsom k moriu: Pamiati Liudmily Bogoslovskoi Igor Krupnik, ed. (Moscow: Moskva, 2016), 647 pp. ISBN 9785600013650.T-Bone Whacks and Caviar Snacks: Cooking with Two Texans in Siberia and the Russian Far East Sharon Hudgins (Denton: University of North Texas Press, 2018), 448 pp. ISBN: 9781574417142.Bij de Joekagieren. Het oudste toendravolk van Noord-Oost Siberië / Life with the Yukaghir: Northeast Siberia’s Oldest Tundra People Cecilia Odé (Lias, Uitgeverij: Verschijningsjass, 2018), 240 pp., €29.95 (paperback). ISBN: 978-90-8803-099-4.

The town of Tiksi and the nearby indigenous village of Bykovskiy are located in northern Yakutia, where the Lena River meets the Arctic Ocean. Both owe their existence to Soviet policies and development plans, one tied to the Northern Sea Route, and the other to a fishing enterprise based on the labor of political prisoners. Post-Soviet transformations since the 1990s have severely altered the economic base of these communities, typically resulting in social, cultural and economic shocks and hardships. At the same time, both communities are affected by environmental change, most visibly in Bykovskiy, where coastal erosion caused by permafrost thaw has been destructing the local graveyard and endangers the housing infrastructure.Interestingly, when we conducted fieldwork there in 2019, our interlocutors seemed to pay very little attention to these environmental problems in the narratives they shared with us. While it might be tempting to accuse local residents of ignoring permafrost thaw and other environmental changes, the situation, we argue, is more complex. In fact, indigenous residents, especially, those making a living by practicing “traditional” activities, such as fishing and reindeer herding, have been observing extreme weather events, shifts in seasonal patterns, and changes in the behavior of land animals and fish for a long time. Similarly, to other parts of the Arctic, this accumulated traditional ecological knowledge has been helpful for adapting to the dramatically changing environment. At the same time, on the discursive and political level, this knowledge has been devalued or, at best, rated as a secondary source of information in relation to a more “advanced” institutionalized expert knowledge. Moreover, the Soviet modernization ideologies and discourses about human-environmental relations have impacted local knowledge, ethics and perceptions of the changing environment. This presentation calls for attention to historical and regional contexts and explores how hierarchical relations between different knowledge systems and how state modernization ideologies inform the ways in which indigenous communities in northern Russia relate to the effects of climate change today.

This chapter covers the state of the art in understanding sustainability of cultures in the Arctic, including main theories, methodological approaches, and case studies. Interest in cultural sustainability has recently increased, and we present advances, knowledge gaps, and future research priorities. First, we review the discussion surrounding culture as a ‘fourth pillar’ of sustainability, highlighting concerns and critiques about this topic. Then we discuss the relationship to other concepts, such as the Anthropocene, the ontological turn, and the noosphere. Finally, we illustrate their applications in specific contexts of Arctic indigenous cultures, discuss language retention, and Russian literature on traditional land use. The chapter highlights theoretical considerations regarding cultural sustainability derived primarily from Scandinavian authors, broad discussions surrounding sustainability and related concepts in Russia, and empirical applications of ideas about culture and sustainability in the North American context.

The Drell-Yan process provides important information on the internal structure of hadrons including transverse momentum dependent parton distribution functions (TMDs). In this work we present calculations for all leading twist structure functions describing the pion induced Drell-Yan process. The non-perturbative input for the TMDs is taken from the light-front constituent quark model, the spectator model, and available parametrizations of TMDs extracted from the experimental data. TMD evolution is implemented at Next-to-Leading Logarithmic precision for the first time for all asymmetries. Our results are compatible with the first experimental information, help to interpret the data from ongoing experiments, and will allow one to quantitatively assess the models in future when more precise data will become available., Comment: The paper is restructured with new discussions and results, TMD evolution is implemented at Next-to-Leading Logarithmic accuracy for all asymmetries. 27 pages and 10 figures

The covariant parton model is generalized to describe quark correlators in a systematic way. Previous results are reproduced for the T-even leading-twist transverse momentum dependent parton distribution functions (TMDs), and for the first time all T-even twist-3 TMDs are evaluated in this model. We apply the approach to evaluate the fully unintegrated quark correlator which allows us to understand the model-specific relations between different TMDs. We verify the consistency of the approach, present numerical results and compare to available TMD parametrizations., Comment: 20 pages, 6 figures

In this interview, Peter Schweitzer discusses his interest in Siberian studies and Arctic research and addresses the so-called “ontological turn” within recent anthropological debates. His earlier academic interests in the hunting and gathering societies of Chukotka and northeastern Siberia took him to the University of Alaska Fairbanks and led to his eventual cooperation with natural science scholars examining climate change in the Arctic region especially in Alaska. Schweitzer’s current research project, “Configurations of Remoteness,” analyzes the construction of the Baykal-Amur Mainline [BAM] as an example of the influence of (transportation) infrastructure on the ecological and social conditions of a region. The research focuses on the mobility and sociality of people living in areas affected by the BAM and questions the construction of remoteness by observing shifts in that mobility and sociality among builders of the BAM. Schweitzer also discusses the current anthropological interest in ontology and suggests that, along with the more-than-human perspective in some of the social sciences, this enables scholars to go beyond the deconstruction of the “other” to allow for “alterity” as a tool in analyzing the world or worlds. The notion of different worlds (and one culture) is more radical than conceiving of one world from different cultural perspectives. A broader approach to human-environment relations that incorporates alterity offers more fruitful tools for researchers, expanding their analytical possibilities.

Selected topics related to the physics of the energy-momentum tensor (EMT) form factors are discussed. The topics are: 1) Fundamental mechanical properties of particles and gravity 2) Mechanical properties of non-spherical particles 3) Gravitational form factors of Goldstone bosons 4) Nucleon's seismology?, Comment: Talk given at 23rd International Spin Physics Symposium - SPIN2018 - 10-14 September, 2018 Ferrara, Italy

In the hadrocharmonium picture a $\overline{c}c$ state and a light hadron form a bound state. The effective interaction is described in terms of the chromoelectric polarizability of the $\overline{c}c$ state and energy-momentum-tensor densities of the light hadron. This picture is justified in the heavy quark limit, and may successfully account for a hidden-charm pentaquark state recently observed by the LHCb Collaboration. In this work we extend the formalism to the description of hidden-charm tetraquarks, and address the question of whether the resonant states observed by LHCb in the $J/\ensuremath{\psi}\text{\ensuremath{-}}\ensuremath{\phi}$ spectrum can be described as hadrocharmonia. This is a nontrivial question because nothing is known about the $\ensuremath{\phi}$ meson energy-momentum-tensor densities. With rather general assumptions about energy-momentum-tensor densities in the $\ensuremath{\phi}$ meson we show that a $\ensuremath{\psi}(2S)\text{\ensuremath{-}}\ensuremath{\phi}$ bound state can exist, and we obtain a characteristic relation between its mass and width. We show that the tetraquark $X(4274)$ observed by LHCb in the $J/\ensuremath{\psi}\text{\ensuremath{-}}\ensuremath{\phi}$ spectrum is a good candidate for a hadrocharmonium. We make predictions which will allow testing this picture. Our method can be generalized to identify other potential hadrocharmonia.

The form factors of the energy-momentum tensor can be accessed via studies of generalized parton distributions in hard exclusive reactions. In this talk we present recent results on the energy-momentum tensor form factors and densities in the bag model formulated in the large-$N_c$ limit. The simplicity and lucidity of this quark model allow us to investigate many general concepts which have recently attracted interest, including pressure, shear forces and angular momentum density inside the nucleon. The results from the bag model are theoretically consistent, and comply with all general requirements.

The energy-momentum tensor (EMT) form factors pave new ways for exploring hadron structure. Especially the D-term related to the EMT form factor D(t) has received a lot of attention due to its attractive physical interpretation in terms of mechanical properties. We study the nucleon EMT form factors and the associated densities in the bag model which we formulate for an arbitrary number of colors Nc and show that the EMT form factors are consistently described in this model in the large-Nc limit. The simplicity of the model allows us to test in a lucid way many theoretical concepts related to EMT form factors and densities including recently introduced concepts like normal and tangential forces, or monopole and quadrupole contributions to the angular momentum distribution. We also study the D-terms of rho-meson, Roper resonance, other N* states and Delta-resonances. Among the most interesting outcomes is the lucid demonstration of the deeper connection of EMT conservation, stability, the virial theorem and the negative sign of the D-term., Comment: 25 pages, 9 figures, typos fixed, reference added, published version

The Arctic is among the world’s regions most affected by ongoing and increasing cultural, socio-economic, environmental and climatic changes. Over the last two decades, scholars, policymakers, extractive industries, local, regional and national governments, intergovernmental forums, and non-governmental organizations have turned their attention to the Arctic, its peoples and resources, and to challenges and benefits of impending transformations. The International Conference on Arctic Research Planning (ICARP) has now transpired three times, most recently in April 2015 with ICARP III. Arctic sustainability is an issue of increasing concern within the Arctic and beyond it, including in ICARP endeavors. This paper reports some of the key findings of a white paper prepared by an international and interdisciplinary team as part of the ICARP-III process, with support from the International Arctic Science Committee Social and Human Sciences Working Group, the International Arctic Social Sciences Associat...

In July 2009, a public meeting was held in the village of Kivalina, Alaska. It was an opportunity for community members to voice their opinions and concerns regarding the Red Dog Mine’s development plans and especially the mine’s new waste management permit. Community members were concerned about the mine’s impacts on their land, their health, and their community as a whole. Mining has been a part of Alaska’s history since the 1800s while oil was discovered in the 1960s and drilling began on the North Slope in 1971. Indigenous communities in Alaska and Greenland are constantly adapting to the economic, political, social, and cultural environments they are a part of and their small-scale economies depend on their abilities to utilize informal economic means such as subsistence harvesting. Resource development is impacting subsistence in major ways: by threatening the natural environment and by increasing the cash flow to Indigenous people resulting in changing lifestyles, priorities, and values.

The chromoelectric polarizability of $J/\psi$ is extracted from lattice QCD data on the nucleon-$J/\psi$ potential in the heavy quark limit. The value of $\alpha(1S) = (1.6 \pm 0.8) \,{\rm GeV}^{-3} $ is obtained. We also comment on the possibility of hadrocharmonia., Comment: 7 pages, 1 figure, expanded discussion, typos fixed, published version

The physics related to the form factors of the energy momentum tensor spans a wide spectrum of problems, and includes gravitational physics, hard exclusive reactions, hadronic decays of heavy quarkonia, and the physics of exotic hadrons described as hadroquarkonia. It also provides access to the "last global unknown property:" the D-term. We review the physics associated with the form factors of the energy-momentum tensor and the D-term, their interpretations in terms of mechanical properties, their applications, and the current experimental status., Comment: typos fixed, published version

This work deals with form factors of the energy-momentum tensor (EMT) of spin-0 particles and the unknown particle property D-term related to the EMT, and is divided into three parts. The first part explores free, weakly and strongly interacting theories to study EMT form factors with the following findings. (i) The free Klein-Gordon theory predicts for the D-term D = -1. (ii) Even infinitesimally small interactions can drastically impact D. (iii) In strongly interacting theories one can encounter large negative D though notable exceptions exist, which includes Goldstone bosons of chiral symmetry breaking. (iv) Contrary to common belief one cannot arbitrarily add "total derivatives" to the EMT. Rather the EMT must be defined in an unambiguous way. The second part deals with the interpretation of EMT form factors in terms of 3D-densities with following results. (i) The 3D-density formalism is internally consistent. (ii) The description is subject to relativistic corrections which are acceptably small in phenomenologically relevant situations including nucleon and nuclei. (iii) The free field result D=-1 persists when a spin-0 boson is not point-like but "heuristically given some internal structure." The third part investigates the question, whether such "giving of an extended structure" can be implemented dynamically, and has the following insights. (i) We construct a consistent microscopic theory which, in a certain parametric limit, interpolates between extended and point-like solutions. (ii) This theory is exactly solvable which is rare in 3+1 dimensions, admits non-topological solitons of Q-ball-type, and has a Gaussian field amplitude. (iii) The interaction of this theory belongs to a class of logarithmic potentials which were discussed in literature, albeit in different contexts including beyond standard model phenomenology, cosmology, and Higgs physics., 26 pages, 3 figures

While Pope Francis’ popularity grows with the media, disenfranchised Roman Catholics, and groups usually unfriendly toward Catholicism, he arouses concern among Christian traditionalists. Much unease comes from mixed messages utilizing a kind of duplicity different from heretical double-truth teachings of the Latin Middle Ages. This use of alternate truths for different audiences reverses the medieval employment, offering the public not the literal, traditional sense (which the Latin Averroists saw as suited for mass consumption) but symbolic or figurative versions once reserved for the sophisticated and erudite, while insisting that more robustly faithful elites still embrace the stricter teachings of the Church. Moreover, this “reversed” double truth can itself be doubled yet again, if the higher elites privately believe the same, weaker, less robust truths disseminated to the masses, although holding them in a more rationalized, sophisticated form. Modernized double truth is not new, but previously the papacy enforced a singularity for Church teaching. With Pope Francis, however, the doubling of truth appears at the peak of the Roman Catholic hierarchy. This has profound consequences for bioethics, (1) constituting a third version of Catholic moral teaching, following both the Tridentine manualist version, and the rationalist, Vatican II modernist rendition, to form a post-modern approach to moral truth, (2) subverting traditional Catholic bioethicists, while calling into question the Roman Catholic Church as a reliable ally against militant secularism in current bioethics. Ancient Christianity as exemplified in the Orthodox Church offers a better model for bioethics, due to its basis in asceticism, worship, and a noetic approach to truth that is not dependent on the vicissitudes of discursive rationality or a chief primate to arbitrate them.

The probably most fundamental information about a particle is contained in the matrix elements of its energy momentum tensor (EMT) which are accessible from hard-exclusive reactions via generalized parton distribution functions. The spin decomposition of the nucleon and Ji sum rule are one example. Less prominent but equally important information is encoded in the stress tensor, related to the spatial components of the EMT, which shows in detail how the strong forces inside the nucleon balance to form a bound state. This provides not only unique insights on nucleon structure. It also leads to fascinating new applications to hadron spectroscopy which allow us to formulate new interpretations of the charmonium-nucleon pentaquarks discovered by LHCb. Recent progress is reviewed in this short overview article., 10 pages, 6 figures, based on talk presented at "QCD Evolution 2016", 30 May to 3 June 2016, Amsterdam

In the present talk, we report a recent investigation on the nucleon form factors of the energy-momentum tensor in nuclear matter, based on the in-medium modified chiral soliton model. The results in free space are in agreement with those from other approaches. We have discussed the changes of the energy-momentum tensor form factors in nuclear matter and the modification of the soliton structure due to the surrounding nuclear environment.

We study the spin-flavor structure of the nucleon's chiral-odd generalized parton distributions (transversity GPDs) in the large-${N}_{c}$ limit of QCD. In contrast to the chiral-even case, only three combinations of the four chiral-odd GPDs are nonzero in the leading order of the $1/{N}_{c}$ expansion: ${\overline{E}}_{T}={E}_{T}+2{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{H}}_{T},{H}_{T}$, and ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{E}}_{T}$. The degeneracy is explained by the absence of spin-orbit interactions correlating the transverse momentum transfer with the transverse quark spin. It can also be deduced from the natural ${N}_{c}$ scaling of the quark-nucleon helicity amplitudes associated with the GPDs. In the GPD ${\overline{E}}_{T}$ the flavor-singlet component $u+d$ is leading in the $1/{N}_{c}$ expansion, while in ${H}_{T}$ and ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{E}}_{T}$ it is the flavor-nonsinglet components $u\ensuremath{-}d$. The large-${N}_{c}$ relations are consistent with the spin-flavor structure extracted from hard exclusive ${\ensuremath{\pi}}^{0}$ and $\ensuremath{\eta}$ electroproduction data, if it is assumed that the processes are mediated by twist-3 amplitudes involving the chiral-odd GPDs and the chiral-odd pseudoscalar meson distribution amplitudes.

The pentaquark ${P}_{c}^{+}(4450)$ recently discovered by the LHCb has been interpreted as a bound state of $\mathrm{\ensuremath{\Psi}}(2S)$ and a nucleon. The charmonium-nucleon interaction which provides the binding mechanism is given, in the heavy-quark limit, in terms of charmonium chromoelectric polarizabilities and densities of the nucleon energy-momentum tensor. In this work, we show in a model-independent way, by exploring general properties of the effective interaction, that $\mathrm{\ensuremath{\Psi}}(2S)$ can form bound states with a nucleon and $\mathrm{\ensuremath{\Delta}}$. Using the Skyrme model to evaluate the effective interaction in the large-${N}_{c}$ limit and estimate $1/{N}_{c}$ corrections, we confirm the results from prior work which were based on a different effective model (chiral quark soliton model). This shows that the interpretation of ${P}_{c}^{+}(4450)$ is remarkably robust and weakly dependent on the details of the effective theories for the nucleon energy-momentum tensor. We explore the formalism further and present robust predictions of isospin-$\frac{3}{2}$ bound states of $\mathrm{\ensuremath{\Psi}}(2S)$ and $\mathrm{\ensuremath{\Delta}}$ with masses around 4.5 GeV and widths around 70 MeV. The approach also predicts broader resonances in the $\mathrm{\ensuremath{\Psi}}(2S)\text{\ensuremath{-}}\mathrm{\ensuremath{\Delta}}$ channel at 4.9 GeV with widths of the order of 150 MeV. We discuss in which reactions these new isospin-$\frac{3}{2}$ pentaquarks with hidden charm can be observed.

Die nicht-erneuerbaren Ressourcen der Arktis sind in den letzten Jahren in den Mittelpunkt vieler Interessen geruckt. Diese reichen von Staaten die dadurch ihre wirtschaftliche und politische Situation verbessern wollen bis zu Umweltschutzern die eine angeblich unberuhrte Wildnis zu retten versuchen und zu indigenen Gruppen die ihre eigenen Souveranitatsanspruche damit demonstrieren wollen. Der vorliegende Beitrag wahlt das Beispiel des Arctic National Wildlife Refuge (ANWR) in Alaska um die Komplexitat dieser Interessenskonflikte zu demonstrieren. Dabei geht es sehr stark um verbriefte und moralische „Rechte“ mit denen Teilnehmer an diesen Auseinandersetzungen argumentieren.

Recently broadened fieldwork opportunities in Siberia have not only enabled the study of current social and cultural processes, but also facilitated a re-assessment of previous periods of rapid social change. One of those was, undoubtedly, the decade following the Russian Revolution, when Russians and other outsiders significantly increased their impact in many areas of Siberia. Fieldwork conducted during the 1990s has provided evidence of a previously unrecognised phenomenon, namely the existence of a syncretistic system of worldview and ritual practice in the Siberian Yupik village Naukan. Similar to so-called “revitalisation movements” elsewhere, it can be interpreted as a reaction to increasing Russian colonial pressure. The present paper attempts to situate the Naukan movement in its cultural and political contexts, in order to provide a post-colonial reading of early 20th century transformations., Les récentes possibilités de mener des travaux de terrain en Sibérie ont permis non seulement l’étude des processus sociaux et culturels actuels mais ont également facilité le réexamen des changements sociaux rapides des périodes antérieures. L’une de ces périodes était, sans aucun doute, la décennie qui a suivi la révolution russe, quand les Russes et d’autres étrangers ont accru sensiblement leur impact dans plusieurs régions de la Sibérie. Un travail de terrain mené dans les années 1990 a permis d’attester un phénomène jusque-là méconnu, à savoir l’existence d’un système syncrétique de vision du monde et de pratiques rituelles dans le village yupik sibérien de Naukan. Comparable à ce qui est appelé ailleurs «mouvements de revitalisation», il peut être interprété comme une réaction à une pression coloniale de plus en plus forte. Cet article tente de situer le mouvement de Naukan dans son contexte culturel et politique afin de donner une lecture post-coloniale des transformations du début du 20e siècle.

Longitudinal, parity-violating single spin asymmetries in proton-proton collisions for RHIC kinematics are considered. The focus of this study is on the production of a single jet as well as a hadron containing a charm quark. While the asymmetry for jets is rather small, considerably larger effects can be expected for the production of charm because of the strongly reduced QCD background. The general outcome of a fixed order calculation is not much affected by the resummation of large threshold logarithms.

The D-term is, like mass and spin, a fundamental property related to the energy-momentum tensor. Yet it is not known experimentally for any particle. In all theoretical studies so far the D-terms of various particles were found negative. Early works gave rise to the assumption the negative sign could be related to stability. The emerging question is whether it is possible to find a field-theoretical system with a positive D-term. To shed some light on this question we investigate Q-clouds, an extreme parametric limit in the Q-ball system. Q-clouds are classically unstable solutions which delocalize, spread out over all space forming an infinitely dilute gas of free quanta, and are even energetically unstable against tunneling to plane waves. In short, these extremely unstable field configurations provide an ideal candidate system for our purposes. By studying the energy-momentum tensor we show that at any stage of the Q-cloud limit one deals with perfectly well-defined and, when viewed in appropriately scaled coordinates, non-dissipating non-topological solitonic solutions. We investigate in detail their properties, and find new physical interpretations by observing that Q-clouds resemble BPS Skyrmions in certain aspects, and correspond to universal non-perturbative solutions in (complex) |\Phi|^4 theory. In particular, we show that also Q-cloud solutions have negative D-terms. Our findings do not prove that D-terms must always be negative. But they indicate that it is unlikely to realize a positive D-term in a consistent physical system., Comment: 23 pages, 7 figures, revised version

The Sivers parton distribution has been predicted to obey a particular ``universality relation'', namely to have opposite sign in semi-inclusive deeply inelastic scattering (SIDIS) and the Drell-Yan process. We discuss how, on the basis of present HERMES data, this remarkable prediction of the QCD factorization approach to the description of single spin asymmetries related to the Sivers effect could be checked experimentally in future experiments at PAX and COMPASS., Comment: Discussion of recent COMPASS data included, minor corrections, figures and references added, close to published version

A review is given on single spin asymmetries in deep inelastic semi-inclusive scattering (SIDIS) and their possible theoretical understanding in the framework of QCD-induced factorization approach, wherefore predictions for transversity from the chiral quark soliton model are used. Arising difficulties to interpret most recent SIDIS data, and the possibility to access the transversity distribution in the Drell-Yan process are discussed., 20 pages, 23 eps-figures, cjpsuppl style files, presented at ASI "Spin and Symmetry", Prague, July 5-10, 2004, to be published in Czechoslovak Journal of Physics, v.55 Suppl

Predictions are made for single spin azimuthal asymmetries due to the Collins effect in pion production from semi-inclusive deeply inelastic scattering off transversely and longitudinally polarized targets for the HERMES and COMPASS experiments. The x-dependence of the asymmetries is evaluated using the parton distribution functions from the chiral quark-soliton model. The overall normalization of the predicted asymmetries is determined by the information on the Collins fragmentation function extracted from previous HERMES data on azimuthal asymmetries from a longitudinally polarized target. The single spin asymmetries from the transversely polarized proton target are found to be about 20% for positive and neutral pions both at HERMES and COMPASS. For a longitudinally polarized target we obtain for COMPASS a sin(phi) asymmetry of 1% and a sin(2phi) asymmetry of about 3%., 10 pages, 9 figures, Ref.[29] added

Spin azimuthal asymmetries in pion electro-production in deep inelastic scattering off longitudinally polarized protons, measured by HERMES, are well reproduced theoretically with no adjustable parameters. Predictions for azimuthal asymmetries for a longitudinally polarized deuteron target are given. The z-dependence of the Collins fragmentation function is extracted. The first information on e(x) is extracted from CLAS A_LU asymmetry.

At leading twist the transverse momentum dependent parton distributions of the pion consist of two functions, the unpolarized ${f}_{1,\ensuremath{\pi}}(x,{\mathbit{k}}_{\ensuremath{\perp}}^{2})$ and the Boer-Mulders function ${h}_{1,\ensuremath{\pi}}^{\ensuremath{\perp}}(x,{\mathbit{k}}_{\ensuremath{\perp}}^{2})$. We study both functions within a light-front constituent model of the pion, comparing the results with different pion models and the corresponding nucleon distributions from a light-front constituent model. After evolution from the model scale to the relevant experimental scales, the results for the collinear pion valence parton distribution function ${f}_{1,\ensuremath{\pi}}(x)$ are in very good agreement with available parametrizations. Using the light-front constituent model results for the Boer-Mulders functions of the pion and nucleon, we calculate the coefficient $\ensuremath{\nu}$ in the angular distribution of Drell-Yan dileptons produced in pion-nucleus scattering, which is responsible for the violation of the Lam-Tung relation. We find a good agreement with the data, and carefully discuss the range of applicability of our approach.

We investigate the energy-momentum tensor form factors of the nucleon in a nuclear medium, based on an in-medium modified $\ensuremath{\pi}$-$\ensuremath{\rho}$-$\ensuremath{\omega}$ soliton model, with medium modifications of the mesons considered. The results allow us to establish general features of medium modifications of the structure of nucleons bound in a nuclear medium.