Exclusive Process Research Articles

A Study of Compton Form Factors in Scalar QED

Deeply virtual Compton scattering has been proposed as a tool to study the structure of hadrons in an exclusive process. The Compton-scattering amplitude can be expressed in terms of scalar quantities, the Compton form factors. Their number depends on the spin of the target as well as the virtuality of the incoming and outgoing photons. For high values of the virtuality Q 2 of the incoming photon, these form factors are expected to scale with inverse powers of Q 2. In this paper these features are studied for a scalar target hadron.

A stepwise approach to developing staged applications

The staged event-driven architecture (SEDA) can be seen as a milestone as regards integration of threads and events in a single model. By decomposing applications into sets of multi-threaded stages connected by event queues, SEDA allows for the use of each concurrency model where most appropriate. Inside each SEDA stage, the number and scheduling policy of threads can be adjusted to enhance performance. SEDA lends itself to parallelization on multi-cores and is well suited for many high-volume data stream processing systems and highly concurrent event processing systems. In this paper, we propose an extension to the staged model that decouples application design from specific execution environments, encouraging a stepwise approach for designing concurrent applications, similar to Foster's PCAM methodology. We also present Leda, a platform that implements this extended model. In Leda, stages are defined purely by their role in application logic, with no concern for locality of execution, and are bound together through asynchronous communication channels, called connectors, to form a directed graph representing the flow of events inside the application. Decisions about the configuration of the application at execution time are delayed to later phases of the implementation process. Stages in the application graph can then be grouped to form clusters, and each cluster is mapped to an exclusive OS process, running on an arbitrary host. Finally, we discuss two example applications which we developed to evaluate the Leda platform.

The Dynamics of Waiting: The Exclusive Queueing Process

The dynamics of pedestrian crowds has been studied intensively in recent years, both theoretically and empirically. However, in many situations pedestrian movement is rather static, e.g. due to jamming near bottlenecks or queueing at ticket counters or the su- permarket checkout. Classically such queues are described by a M/M/1 queue which neglects the internal structure (density profile) of the queue by focussing on the queue length as the only dynamical variable. This is different in the exclusive queueing process (EQP) which considers the queue on a microscopic level. It is equivalent to a totally asymmetric exclusion process (TASEP) of varying length for which many exact results can be obtained. The EQP has a surprisingly rich phase diagram with respect to the arrival probability α and the service probability β The behaviour at the phase transition line is much more complex than for the TASEP. It is nonuniversal and depends strongly on the update procedure used.

MEASUREMENT OF DIFFERENTIAL CROSS SECTIONS OF p(e, e′π+)n FOR HIGH-LYING RESONANCES AT Q2 < 5 GeV2

The exclusive electroproduction process ep → e′nπ+ was measured in the range of the invariant mass for nπ+ system 1.6 GeV ≤ W ≤ 2.0 GeV, and the photon virtuality 1.8 GeV2 ≤ Q2 ≤ 4.0 GeV2 using CLAS. For the first time, these kinematics are probed in exclusive π+ production from the protons with nearly full coverage in the azimuthal and polar angles of the nπ+ center-of-mass system. In this experiment, approximately 39,000 differential cross-section data points were measured. In this conference proceeding, preliminary results of our latest analysis work are presented on differential cross sections and structure functions as well as Legendre Moments.

Study of associated charmonium J/Ψ production in $\bar{p} p \rightarrow\pi^{0} +J/\varPsi$

The exclusive charmonium production process $\bar{p} p \rightarrow \pi^{0} +J/\varPsi$ is investigated for the planned $\bar{p} p$ experiment with the PANDA detector at GSI/FAIR. The measured exclusive cross section of this reaction was reported first by the E760 and E835 collaborations at Fermilab, in the energy range (3525 MeV) of charmonium state h c production. The recent measurements of the charmonium decay widths reported by the CLEO and BES collaborations allow one to make constraints on model assumptions.

Critical behavior of the exclusive queueing process

The exclusive queueing process (EQP) is a generalization of the classical M/M/1 queue. It is equivalent to a totally asymmetric exclusion process (TASEP) of varying length. Here we consider two discrete-time versions of the EQP with parallel and backward-sequential update rules. The phase diagram (with respect to the arrival probability α and the service probability β) is divided into two phases corresponding to divergence and convergence of the system length. We investigate the behavior on the critical line separating these phases. For both update rules, we find diffusive behavior for small service probability . However, for it becomes sub-diffusive and nonuniversal: the critical exponents characterizing the divergence of the system length and the number of customers are found to depend on the update rule. For the backward-update case, they also depend on the hopping parameter p, and remain finite when p is large, indicating a first-order transition.

Probes of the small x gluon via exclusive J/ψ and Υ production at HERA and the LHC

New, more precise data on diffractive J/ψ photoproduction and on exclusive J/ψ production in the process pp → p + J/ψ + p at the LHC allow a better constraint on the low-x gluon distribution in the domain of relatively low scales Q 2 ~ 2–6 GeV2. We account for the ‘skewed’ effect and for the real part of the amplitude, as well as for the absorptive corrections in the case of the exclusive process pp → p + J/ψ + p. The predictions for exclusive J/ψ production at $ \sqrt{s} $ = 8 and 14 TeV and for exclusive $ Y $ (1S) production at 7, 8 and 14 TeV are also given. We present results at leading and next-to-leading order.

Visions of what inclusive education can be – With emphasis on kindergartens

The research questions of the article are: What takes place in the professional cooperative work of including children with special needs in kindergartens and in counteracting exclusive process? How are views on children and ethics expressed through practice and in reflections on practice among the staff in kindergarten? What constitutes ‘pedagogical presence’ ‘attentive love’ and children's participation in developing pedagogical practice A common understanding of these concepts are highlighted by Fromm's understanding of ‘be-mode’ and ‘have-mode’ as different modes of orientation toward ourselves and the world. The article draws on critical social theory on preschool education and is based on empiric findings from ethnographic studies in two kindergartens. While planning and regulating the practice according to a biased view on ‘what children need’ earlier were main topic in the kindergartens studied, now concentration on listening to and ‘reading’ the children is focused, and thus expansion of the interests and questions the children themselves bring in is facilitated. The new practice can be seen as a resistance movement against the growth of an instrumental and technical approach to preschool education the last years.

Determination of exotic hadron structure by constituent-counting rule for hard exclusive processes

We propose to use hard exclusive production of an exotic hadron for finding its internal quark-gluon configuration by the constituent-counting rule in perturbative QCD. In particular, the cross section for the exclusive process $\pi^- + p \to K^0 + \Lambda (1405)$ is estimated at the scattering angle $\theta=90^\circ$ in the center-of-mass frame by using current experimental data. In comparison, the cross section for the ground-state $\Lambda$ production $\pi^- + p \to K^0 + \Lambda$ is also shown. We suggest that the internal quark configuration of $\Lambda (1405)$ should be determined by the asymptotic scaling behavior of the cross section. If it is an ordinary three-quark baryon, the scaling of the cross section is $s^{8} d\sigma /dt=$constant, whereas it is $s^{10} d\sigma /dt=$constant if $\Lambda (1405)$ is a five-quark hadron, where $s$ and $t$ are Mandelstam variables. Such a measurement will be possible, for example, by using the high-momentum beamline at J-PARC. In addition, another exclusive process $\gamma + p \to K^+ + \Lambda (1405)$ could be investigated at LEPS and JLab for finding the nature of $\Lambda (1405)$. We indicate that the constituent-counting rule could be used as a valuable quantity in determining internal structure of exotic hadrons by high-energy exclusive processes, where quark-gluon degrees of freedom explicitly appear. Furthermore, it is interesting to investigate the transition from hadron degrees of freedom to quark-gluon ones for exclusive exotic-hadron production processes.

Asymmetric synthesis of an enantiomerically pure rivastigmine intermediate using ketoreductase

A novel chemo-enzymatic synthesis of (S)-rivastigmine using ketoreductases with NADH/NADPH as the proton donor has been demonstrated. An exclusive enzymatic process has been developed by exploring the possible ketoreductases by screening to identify enzymes useful for the preparation of the (S)-isomer intermediate, and scaling up of the enzymatic process for the production of an adequate, enantiomerically pure precursor of rivastigmine and for the total synthesis of (S)-rivastigmine.

Density profiles of the exclusive queuing process

The exclusive queuing process (EQP) incorporates the exclusion principle into classic queuing models. It is characterized by, in addition to the entrance probability α and exit probability β, a third parameter: the hopping probability p. The EQP can be interpreted as an exclusion process of variable system length. Its phase diagram in the parameter space (α,β) is divided into a convergent phase and a divergent phase by a critical line which consists of a curved part and a straight part. Here we extend previous studies of this phase diagram. We identify subphases in the divergent phase, which can be distinguished by means of the shape of the density profile, and determine the velocity of the system length growth. This is done for EQPs with different update rules (parallel, backward sequential and continuous time). We also investigate the dynamics of the system length and the number of customers on the critical line. They are diffusive or subdiffusive with non-universal exponents that also depend on the update rules.

CROSS-SECTION FOR DOUBLE CHARMONIUM PRODUCTION IN ELECTRON–POSITRON ANNIHILATION AT ENERGY $\sqrt{s} = 10.6 {\rm GeV}$

In this work we study the process e++e-→J/Ψ+ηc at energy [Formula: see text] observed recently at B-factories whose measurements were made by Babar and Belle groups. We calculate the cross-section for this process in the Bethe–Salpeter formalism under Covariant Instantaneous Anstaz. To simplify our calculation, the heavy quark approximation is employed in the quark and gluon propagators. In the exclusive process of e+e- annihilation into two heavy quarkonia, the cross-section calculated in this scenario is compatible with the experimental data of Babar and Belle.

Gephyrin-mediated γ-Aminobutyric Acid Type A and Glycine Receptor Clustering Relies on a Common Binding Site

Gephyrin is the major protein determinant for the clustering of inhibitory neurotransmitter receptors. Earlier analyses revealed that gephyrin tightly binds to residues 398-410 of the glycine receptor β subunit (GlyR β) and, as demonstrated only recently, also interacts with GABA(A) receptors (GABA(A)Rs) containing the α1, α2, and α3 subunits. Here, we dissect the molecular basis underlying the interactions between gephyrin and GABA(A)Rs containing these α-subunits and compare them to the crystal structure of the gephyrin-GlyR β complex. Biophysical and biochemical assays revealed that, in contrast to its tight interaction with GlyR β, gephyrin only loosely interacts with GABA(A)R α2, whereas it has an intermediate affinity for the GABA(A)R α1 and α3 subunits. Despite the wide variation in affinities and the low overall sequence homology among the identified receptor subunits, competition assays confirmed the receptor-gephyrin interaction to be a mutually exclusive process. Selected gephyrin point mutants that critically weaken complex formation with GlyR β also abolished the GABA(A)R α1 and α3 interactions. Additionally, we identified a common binding motif with two conserved aromatic residues that are central for gephyrin binding. Consistent with the biochemical data, mutations of the corresponding residues within the cytoplasmic domain of α2 subunit-containing GABA(A)Rs attenuated clustering of these receptors at postsynaptic sites in hippocampal neurons. Taken together, our experiments provide key insights regarding similarities and differences in the complex formation between gephyrin and GABA(A)Rs compared with GlyRs and, hence, the accumulation of these receptors at postsynaptic sites.

Exact dynamical state of the exclusive queueing process with deterministic hopping

The exclusive queueing process (EQP) has recently been introduced as a model for the dynamics of queues that takes into account the spatial structure of the queue. It can be interpreted as a totally asymmetric exclusion process of varying length. Here we investigate the case of deterministic bulk hopping p=1 that turns out to be one of the rare cases where exact nontrivial results for the dynamical properties can be obtained. Using a time-dependent matrix product form we calculate several dynamical properties, e.g., the density profile of the system.

CAN'T BUY ME LOVE? A FIELD EXPERIMENT EXPLORING THE TRADE-OFF BETWEEN INCOME AND CASTE-STATUS IN AN INDIAN MATRIMONIAL MARKET

I. INTRODUCTION The relationship between economic motive and observance of discriminatory social customs is hardly new to economists. This is implicit in the writings of Becker (1957, 1973, 1974) on discrimination and other social customs, and explicit in Arrow's essay (1972) on discrimination and Akerlof's work (1980) on the interactive relationship between economic incentives and discriminatory social customs. As scholars like Becker, Arrow, and Akerlof have investigated the relationship between economic incentives and the prevalence of custom-based discrimination (of which status-based discrimination is an example), it is natural to consult the related empirical evidence on the impact of economic incentives on the extent of status-based discrimination. Surprisingly, the extant empirical literature is mostly silent on how economic incentives may directly interact with status-based discrimination. (1) This is atypical as one would be hard-pressed to find an issue as weighty as status-based discrimination, yet our knowledge in this aspect remains oddly limited. Our study aspires to rectify this gap. This study investigates whether and what magnitude of economic incentive can diminish the incidence of status-based discrimination by designing a controlled field experiment in an actual marketplace--a reputable arranged marriage market--that is conducted via newspaper advertisements. The existing literature suggests that this market might be especially prone to strong discriminatory mate-selection behavior based on the social identity/status of an individual, where caste identity of an individual is an easily measured indicator of social status. The genesis of this discrimination can be attributed to a high-status female's concern for a decline in her social status if she engages in a marital relationship with a low-status male. Against this backdrop, we ask whether a low-status male could attempt to weaken this enduring form of discrimination by providing systematic economic incentive (in the form of high monthly groom incomes) to a high-status female so that the former's marriage proposal receives preliminary consideration by the latter, conditional on both individuals' participation in this market. The marketplace that we utilize is a well-functioning arranged marriage market, conducted via matrimonial advertisements in a widely circulated Bengali language newspaper. Marriageable males in this market typically advertise their caste and income information, among other attributes. After these advertisements appear in the newspaper, interested families contact the advertiser, mostly in form of detailed letters, expressing their interest in that advertisement. This provides a confidential and reliable measure of intent of the interested party, in this case, females. Therefore, the conjunction of an exceptionally strong status-based mate selection behavior, a reputed market for arranged marriages, and an exclusive correspondence process furnish us with a unique opportunity to investigate the main research hypothesis of our study. To the best of our knowledge, this is the first field experiment that exclusively focuses on how economic incentives can influence status-based discrimination in an actual market. (2) To operationalize the experiment, we create nine unique matrimonial advertisements, each representing a fictitious groom type. (3) These potential grooms belong to one of the three blocks where each block contains three grooms from a given caste group. We vary the caste-status across these blocks. We consider three different caste groups--high, middle, and low, strictly ranked so in the study region. We vary the income features of grooms within a block. We consider three different monthly income levels (i.e., high, medium, and low) that are considered feasible for each caste group in the study region. Furthermore, we randomly assign other characteristics relevant for this market, to all the potential grooms so that these features, on average, do not affect the behavior of responders. …

Dynamical analysis of the exclusive queueing process

Recently, the stationary state of a parallel-update totally asymmetric simple exclusion process with varying system length, which can be regarded as a queueing process with excluded-volume effect (exclusive queueing process), was obtained [C Arita and D Yanagisawa, J. Stat. Phys. 141, 829 (2010)]. In this paper, we analyze the dynamical properties of the number of particles [N(t)] and the position of the last particle (the system length) [L(t)], using an analytical method (generating function technique) as well as a phenomenological description based on domain-wall dynamics and Monte Carlo simulations. The system exhibits two phases corresponding to linear convergence or divergence of [N(t)] and [L(t)]. These phases can both further be subdivided into high-density and maximal-current subphases. The predictions of the domain-wall theory are found to be in very good agreement quantitively with results from Monte Carlo simulations in the convergent phase. On the other hand, in the divergent phase, only the prediction for [N(t)] agrees with simulations.

A slab detachment and delamination model for the generation of Carboniferous high-potassium I-type magmatism in the Eastern Pontides, NE Turkey: The Köse composite pluton

The Hercynian Köse composite pluton (KCP) is located in the Eastern Pontides, Turkey, and consists of two units of high-K calc-alkaline, primarily peraluminous granites: (i) the internal body, and (ii) the external body. The internal body, which was emplaced at 322–318 Ma ( 40Ar/ 39Ar ages on biotite and hornblende, respectively), displays a wide compositional range (49–71 wt.% SiO 2) and contains several lithologies: hybrid equigranular rocks, microgranular magmatic enclaves, mafic dikes, porphyry dikes and mylonites. The external body, which was emplaced at 306.7 Ma ( 40Ar/ 39Ar age on K-feldspar), consists exclusively of monzogranite (> 71 wt.% SiO 2). Field relationships, mineralogy, major- and trace element geochemistry, and initial Sr–Nd isotope values ( I Sr = 0.70821 to 0.71002, e Nd(t) = −6.6 to −8.0) show that the internal body was differentiated and evolved by crystal fractionation and magma mixing processes. The end-members of the mixing process were a mafic rock and a felsic rock. Mafic magma was derived from a relatively deep-seated (25–30 km) crustal storage reservoir, not directly from the mantle, and underwent significant differentiation by fractional crystallization and crustal contamination before mixing. In addition, these magma storages probably supplied the additional heat necessary to initiate crustal melting. Some of the additional heat may have also been released by the radiogenic decay of heat producing elements. Eventually, the existing felsic magma from the melting of K-bearing meta-greywackes was raised to its emplacement level at a depth of ~ 10–16 km. After partial crystallization, it was sporadically intruded by modified mafic magma from the deeper crustal reservoir to generate hybrid rocks. The hybrid rocks were then elevated to a shallower depth by normal faults during the collapse of the orogen and erosion. Mylonites that were later overprinted by pseudotachylites are typically constrained to the internal body and are regarded as markers of this event. The external body is characterized by a significantly less radiogenic and limited range of Sr–Nd isotope values ( I Sr = 0.70639 to 0. 70792, e Nd(t) = −4.4 to −6.5) than those of the internal body and a lack of rocks documenting the open system differentiation processes. Fractional crystallization is the exclusive process responsible for the elemental range within the body. The rocks also contain less biotite relative to those of the internal body. All these involve less K-bearing mid-crustal rocks (orthogneisses) in their source, which was probably located at depths near the lower crust. The absence of purely lower crustal-derived melts can be explained by the removal of this type of material during the formation of the parental melt. This melt later ascended to its emplacement level at a depth of around ~ 5–10 km and cut the hybrid rocks of the internal body and regional metamorphic rocks that had been raised previously due to ongoing erosion. The melt that injected into the cracks of the internal body crystallized into porphyries because there was not enough time for the entire crystallization of magma. The data presented here indicate that late Early Carboniferous and Late Carboniferous magmatism occurred in a collisional setting. Slab detachment and subsequent delamination seem to be the most plausible mechanisms for the generation of the Hercynian high-K calc-alkaline magmatism in the Eastern Pontides, Turkey.

Deeply virtual compton scattering at HERMES

Generalized Parton Distributions (GPDs) provide a way to access total angular momenta of partons and give a multidimensional picture of the nucleon structure. Deeply Virtual Compton Scattering (DVCS) is the most direct exclusive process to study GPDs. Different azimuthal cross-section asymmetries with respect to beam helicity, beam charge, and target polarization have been measured in the HERMES experiment. A recoil detector was installed at HERMES to directly detect the recoil proton.

Photoproduction of a [formula omitted] pair with a large invariant mass and transversity generalized parton distribution

The chiral-odd transversity generalized parton distributions (GPDs) of the nucleon can be accessed experimentally through the exclusive photoproduction process γ+N→π+ρ+N′, in the kinematics where the meson pair has a large invariant mass and the final nucleon has a small transverse momentum, provided the vector meson is produced in a transversally polarized state. We calculate perturbatively the scattering amplitude at leading order in αs. We build a simple model for the dominant transversity GPD HT(x,ξ,t) based on the concept of double distribution. We estimate the unpolarized differential cross section for this process in the kinematics of the Jlab and Compass experiments. Counting rates show that the experiment looks feasible with the real photon beam characteristics expected at JLab@12 GeV, and with the quasi real photon beam in the Compass experiment.

Interaction of 17F with a 208Pb target below the Coulomb barrier

The interaction of loosely bound (Sp = 600 keV) 17F ions with a 208Pb target was studied at Elab = 86 MeV, below the Coulomb barrier, by measuring the differential cross-section for the quasi-elastic scattering and the cross-section for the exclusive breakup process 17F \( \rightarrow\)16O + p . The small reaction and exclusive breakup cross-sections confirm the small reactivity of this system, even at low energy, and indicates that the 17F small binding energy plays a minor role in the reaction dynamics.