Hard exclusive wide-angle processes

In this talk the handbag approach to hard exclusive wide-angle processes is reviewed and applications, as for instance two-photon annihilations into pairs of mesons, are discussed.Comment: 11 pages, 8 figures, using latex2e, invited talk presented at Meson 2012, Cracow 201

Exclusive meson pair production in proton-proton collisions

We present a study of the exclusive production of meson pairs in the four-body $pp \to pp \pi^{+} \pi^{-}$, $pp K^{+}K^{-}$ reactions at high energies which constitute an irreducible background to resonance states (e.g. $\phi$, $f_{2}(1270)$, $f_{0}(1500)$, $f_{2}'(1525)$, $\chi_{c0}$). We consider central diffractive contribution mediated by Pomeron and Reggeon exchanges and new diffractive mechanism of emission of pions/kaons from the proton lines. We include absorption effects due to proton-proton interaction and pion/kaon rescattering. Predictions for the total cross section and differential distributions in pion/kaon rapidity and transverse momentum as well as two-pion/kaon invariant mass are presented for the RHIC, Tevatron and LHC colliders. Finally we consider a measurement of exclusive production of a scalar $\chi_{c0}$ meson via $\chi_{c0} \to \pi^{+} \pi^{-}$, $K^{+} K^{-}$ decay.Comment: 4 pp., 4 figures, talk presented by PL at MESON2012 - 12th International Workshop on Meson Production, Properties and Interaction, Krakow, Poland, 31 May - 5 June 201

Open charm meson production at LHC

We discuss charm production at the LHC. The production of single $c \bar c$ pairs is calculated in the $k_t$-factorization approach. We use Kimber-Martin-Ryskin unintegrated gluon distributions in the proton. The hadronization is included with the help of Peterson fragmentation functions. Transverse momentum and pseudorapidity distributions of charmed mesons are presented and compared to recent results of the ALICE, LHCb and ATLAS collaborations. Furthermore we discuss production of two pairs of $c \bar c$ within a simple formalism of double-parton scattering (DPS). Surprisingly large cross sections, comparable to single-parton scattering (SPS), are predicted for LHC energies. We discuss perspectives how to identify the double scattering contribution. We predict much larger cross section for large rapidity distance between charm quarks from different hard parton scatterings compared to single scattering.Comment: 5 pages, 4 figures, talk given by R. Maciula at the MESON2012 - 12th International Workshop on Meson Production, Properties and Interaction, 31 May - 5 June 2012, Krakow, Polan

Exclusive production of π+π−\pi^+\pi^- and π0π0\pi^0\pi^0 pairs in photon-photon and in ultrarelativistic heavy ion collisions

The $\gamma\gamma\to\pi\pi$ reactions are discussed. To describe those processes, we include dipion continuum, resonances, high-energy pion-pion rescatterings, $\rho$ meson exchange and pQCD Brodsky-Lepage mechanisms. The cross section for the production of pion pairs in photon-photon collisions in peripheral heavy ion collisions is calculated with the help of Equivalent Photon Approximaption (EPA) in the impact parameter space. We show predictions at $\sqrt{s_{NN}}=3.5$ TeV which could be measured e.g. by the ALICE collaboration at the LHC.Comment: 4 pages, 7 figures, 1 table, talk by M. Klusek-Gawenda at MESON2012, 31 May - 5 June 2012, Krakow, Polan

A Dispersive Treatment of Kℓ4K_{\ell4} Decays

$K_{\ell4}$ are for several reasons an especially interesting decay channel of $K$ mesons: $K_{\ell4}$ decays allow an accurate measurement of a combination of $S$-wave $\pi\pi$ scattering lengths, one form factor of the decay is connected to the chiral anomaly and the decay is the best source for the determination of some low energy constants of ChPT. We present a dispersive approach to $K_{\ell4}$ decays, which takes rescattering effects fully into account. Some fits to NA48/2 and E865 measurements and results of the matching to ChPT are shown.Comment: 4 pages, talk given by PS at MESON2012 - 12th International Workshop on Meson Production, Properties and Interaction, Krak\'ow, Poland, 31 May - 5 June 201

eta' meson under partial restoration of chiral symmetry in nuclear medium

We shed light upon the eta' mass in nuclear matter in the context of partial restoration of chiral symmetry, pointing out that the U_{A}(1) anomaly effects causes the eta'-eta mass difference necessarily through the chiral symmetry breaking. As a consequence, it is expected that the eta' mass is reduced by order of 100 MeV in nuclear matter where partial restoration of chiral symmetry takes place. The discussion given here is based on Ref. [1].Comment: 3 pages, 2 figures. Contribution to Meson201

Strangeness production in antiproton-nucleus annihilation

The results of the microscopic transport calculations of $\bar p$-nucleus interactions within a GiBUU model are presented. The dominating mechanism of hyperon production is the strangeness exchange processes $\bar K N \to Y \pi$ and $\bar K N \to \Xi K$. The calculated rapidity spectra of $\Xi$ hyperons are significantly shifted to forward rapidities with respect to the spectra of $S=-1$ hyperons. We argue that this shift should be a sensitive test for the possible exotic mechanisms of $\bar p$-nucleus annihilation. The production of the double $\Lambda$-hypernuclei by $\Xi^-$ interaction with a secondary target is calculated.Comment: Proceedings of the 12th Int. Workshop on Meson Production, Properties and Interaction (MESON-2012), Cracow, 31.05-05.06.201

Efeito da exposição à deprivação materna e/ou dieta hipercalórica em parâmetros de desenvolvimento neuromotor, ponderais, comportamentais e neuroquímicos em ratos

O consumo de dieta ocidental altamente palatável e hipercalórica expõe os indivíduos, desde a primeira infância, a uma alimentação obesogênica. Essa dieta aumenta o prazer relacionado ao consumo alimentar estimulando o sistema de recompensa e alterando vias de sinalização do sistema nervoso central (SNC). Esses eventos são relacionados à perda do controle adequado do apetite. Por outro lado, exposição ao estresse também tem importante relação com controle alimentar. Uma importante fonte de estresse é a deprivação materna (DM) no período neonatal, trazendo prejuízos ao indivíduo ao longo da vida. Estudos em animais têm demonstrado que o estresse induzido pela DM nesse período provoca alterações neuroquímicas. Essas alterações têm sido relacionadas a transtornos mentais como ansiedade e depressão, assim como, obesidade na idade adulta. Considerando a relevância do tema, nessa dissertação avaliamos o efeito da DM no período neonatal e/ou exposição à dieta hipercalórica (leite condensado) após o desmame sobre parâmetros de desenvolvimento neuromotor, ponderais, comportamentais e neuroquímicos em ratos Wistar adultos jovens machos e fêmeas. Foram utilizados 64 ratos Wistar machos e fêmeas distribuídos em quatro grupos: Controle (C) – sem DM e exposto à dieta padrão; Deprivação Materna (DM)- animais submetidos à DM (P1-P10) e exposto à dieta padrão; Dieta Hipercalórica (DH) - sem DM e exposto à dieta hipercalórica (alimento palatável/leite condensado); e Deprivação Materna e Dieta Hipercalórica (DMDH)- animais submetidos à DM (P1-P10) e expostos à dieta hipercalórica (alimento palatável/leite condensado). Os efeitos da DM nos padrões de reflexos iniciais nos filhotes foram avaliados por meio dos testes de geotaxia negativa e endireitamento postural, assim como seus efeitos sobre a resposta nociceptiva avaliada por meio do teste da Placa Quente (PQ) e do Tail-Flick (TFL). Avaliamos também o comportamento do tipo ansioso por meio do teste do Labirinto em Cruz Elevado - Elevated Plus Maze (EPM) e a atividade locomotora pelo teste de Campo Aberto (CA) antes do desmame (P21). A partir de P21, os animais dos grupos DH e DMDH foram expostos a uma dieta hipercalórica/alimento palatável (leite condensado) por três semanas e novamente avaliados a resposta nociceptiva, o comportamento do tipo ansioso e a atividade locomotora. Salientamos que foi analisado o efeito do gênero sobre todos os parâmetros analisados. Após a segunda leva de testes comportamentais, os animais foram mortos (P44) e retirados córtex cerebral, hipocampo e hipotálamo para a realização de dosagens bioquímicas. Foram dosados níveis do fator de desenvolvimento neuronal do encéfalo (BDNF), fator de crescimento neuronal 1 (NGF-1) e de citocinas pro-inflamatórias (IL6 e TNF-α) e anti-inflamatória (IL10). Nossos resultados demonstram que a exposição à DM induz, em curto prazo (entre P20 e P21), alterações no desenvolvimento motor inicial, resposta nociceptiva térmica (aumento do limiar nociceptivo –PQ e TFL-fêmeas), aumento da atividade locomotora de fêmeas devido ao maior número de cruzamentos externos e do tempo de grooming em machos, o que pode estar relacionado a alterações em sistema dopaminérgico (teste CA); aumento no tempo de permanência nos braços abertos dos animais deprivados sugerindo um efeito ansiolítico dessa intervenção, aumento no número de non-protected head dipping (NPHD) em machos, comportamentos relacionados à atividade exploratória e avaliação de risco (teste do EPM). Os efeitos tardios da DM, avaliados entre P42 e P43, foram observados na resposta nociceptiva (diminuição do limiar nociceptivo dos machos -TFL) e no teste EPM apenas os machos apresentaram maior número de rearings, indicativo de aumento na atividade exploratória dependente de gênero da DM. Quando expostos à DH, os machos apresentaram maior ganho de peso e índice de Lee. A DH induziu um aumento no peso relativo de tecido adiposo, independente do sexo. Foram observados efeitos tardios da DM e do gênero sobre os níveis de BDNF nas estruturas cerebrais avaliadas. Efeito da exposição à DH foi observado apenas nos níveis hipotalâmicos de NGF-1. Fêmeas apresentaram níveis mais elevados de BDNF e IL-6 em hipocampo e hipotálamo, e de TNF-α em hipotálamo. Em níveis corticais de IL10 houve interação entre gênero e DM. Concluindo, esses achados contribuem para um maior entendimento dos possíveis efeitos da exposição precoce a um estressor e/ou ao alimento palatável na infância/adolescência, demonstrando diferentes respostas de acordo com gênero às intervenções propostas. Além disso, diferenças entre o gênero per se foram observadas, sugerindo a importância de incluir ambos os sexos nas investigações pré-clínicas a fim de trazer maior translacionalidade aos estudos.The consumption of a highly palatable and hypercaloric Western diet exposes individuals, from early infancy, to an obesogenic diet. This diet increases the pleasure related to food consumption by stimulating the reward system and altering Central Nervous System (CNS) signaling pathways. These events are related to loss of adequate appetite control. On the other hand, stress exposure also has important relation with food control. An important source of stress is maternal deprivation (MD) in the neonatal period, causing lifetime impacts. Animal studies have shown that stress induced by MD causes neurochemical changes. These changes have been related to mental disorders such as anxiety and depression, as well as obesity in adulthood. Considering the relevance of this topic, in this dissertation we evaluated the effect of MD in neonatal period and / or exposure to hypercaloric diet (condensed milk) after weaning on neuromotor, ponderal, behavioral and neurochemical development parameters in young adult male and female Wistar rats. Sixty-four male and female Wistar rats were distributed into four groups: Control (C) - without MD and exposed to the standard diet; Maternal Deprivation (MD) - animals submitted to MD (P1-P10) and exposed to the standard diet; Hypercaloric (HD) diet - without MD and exposed to the hypercaloric diet (palatable food / condensed milk); and Maternal Deprivation and Hypercaloric Diet (MDHD) - animals submitted to MD (P1-P10) and exposed to the hypercaloric diet (palatable food / condensed milk). The effects of MD on the initial reflex patterns in the pups were evaluated by the negative geotaxis and righting reflex tests, as well as their effects on the nociceptive response assessed by the Hot Plate (HP) and Tail-Flick tests (TFL). We also evaluated the anxiety-like behavior through the Elevated Plus-Maze (EPM) test and the locomotor activity by the Open Field Test (OF) before weaning (P21). From P21, the animals from the HD and MDHD groups were exposed to a hypercaloric / palatable diet (condensed milk) for three weeks and the nociceptive response, anxious-like behavior and locomotor activity were evaluated once again. We emphasize that the effect of gender in all parameters was analyzed. After the second set of behavioral tests, the animals were killed (P44) and the cerebral cortex, hippocampus and hypothalamus were removed for biochemical measurements. Levels of neuronal brain development factor (BDNF), neuronal growth factor 1 (NGF-1) and proinflammatory cytokines (IL6 and TNF-α) and anti-inflammatory cytokine (IL10) were measured. Our results demonstrate that the exposure to MD induces, in the short term, changes in the initial motor development, thermal nociceptive response (increase of the nociceptive threshold - PQ and TFL-females), increases locomotor activity of females due to the greater number of outter crossings and grooming time in males, which may be related to changes in dopaminergic system (OF test); increases time spent in open arms of deprived animals suggesting an anxiolytic effect of this intervention, increases the number of non-protected head dipping (NPHD) in males, behaviors related to exploratory activity and risk assessment (EPM test). The late effects of DM, evaluated between P42 and P43, were observed in the nociceptive response (decrease males’ nociceptive thresholds in the TFL) and in the EPM test males presented a greater number of rearings, indicative of an increase in exploratory activity dependent on gender. When exposed to HD, males showed greater weight gain and Lee index. HD induced an increase in the relative adipose tissue weight, regardless of sex. Late effects of MD and gender on the BDNF levels were observed in the brain structures evaluated. Effect of HD exposure was observed only on the hypothalamic levels of NGF-1. Females presented higher levels of BDNF and IL-6 in hippocampus and hypothalamus, and TNF-α in the hypothalamus. At cortical levels of IL-10 there was interaction between gender and MD. In conclusion, these findings contribute to a better understanding of the possible effects of early exposure to a stressor and / or palatable food in childhood / adolescence, demonstrating different responses according to gender to the proposed interventions. In addition, gender differences per se were observed, suggesting the importance of including both genders in preclinical investigations in order to bring greater translationality to the studies

Hydrogen Spectroscopy with a Lamb-shift Polarimeter - An Alternative Approach Towards Anti-Hydrogen Spectroscopy Experiments

A Lamb-shift polarimeter, which has been built for a fast determination of the polarization of protons and deuterons of an atomic-beam source and which is frequently used in the ANKE experiment at COSY-J\"ulich, is shown to be an excellent device for atomic-spectroscopy measurements of metastable hydrogen isotopes. It is demonstrated that magnetic and electric dipole transitions in hydrogen can be measured as a function of the external magnetic field, giving access to the full Breit-Rabi diagram for the $2^2S_{1/2}$ and the $2^2P_{1/2}$ states. This will allow the study of hyperfine structure, $g$ factors and the classical Lamb shift. Although the data are not yet competitive with state-of-the-art measurements, the potential of the method is enormous, including a possible application to anti-hydrogen spectroscopy.Comment: 6 pages, 7 figures, accepted by European Physical Journal