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We investigate the sensitivity of the three-nucleon system to changes in the neutron–neutron scattering length to next-to-leading order in the pionless effective field theory, focusing on the triton– 3 He binding energy difference and neutron–deuteron elastic scattering. Due to the appearance of a proton–deuteron three-body counterterm at this order, the triton– 3 He binding energy difference remains consistent with the experimental value even for large positive neutron–neutron scattering lengths while the elastic neutron–deuteron scattering phase shifts are insensitive. We conclude that a bound dineutron cannot be excluded to next-to-leading order in pionless EFT. [ABSTRACT FROM AUTHOR]

Abstract: The axial charge of the nucleon and the pion decay constant are computed in two-flavor lattice QCD. The simulations are carried out on lattices of various volumes and lattice spacings. Results are reported for pion masses as low as . Both quantities, and , suffer from large finite size effects, which to leading order ChEFT and ChPT turn out to be identical. By considering the naturally renormalized ratio , we observe a universal behavior as a function of decreasing quark mass. From extrapolating the ratio to the physical point, we find , using the physical value of as input and to set the scale. In a subsequent calculation we attempt to extrapolate and separately to the infinite volume. Both volume and quark mass dependencies of and are found to be well described by ChEFT and ChPT. We find at the physical point and . Both sets of results are in good agreement with experiment. As a by-product we obtain the low-energy constant . [Copyright &y& Elsevier]

Abstract: U-spin breaking corrections up to third order are studied in decays to pairs of a charged pion or kaon. We show that first and third order corrections vanish in , while second order corrections cancel each other experimentally at a one percent level. We compare this ratio with three other ratios of amplitudes involving these same decays, for which expansions up to and including second order are obtained. A nonlinear relation between these four ratios is shown to hold excluding third order U-spin breaking at a fraction of a percent. Isospin breaking in this relation and in the above equality is suppressed by both isospin and U-spin breaking parameters. The ratios and determine values of 0.05 and 0.30 for real parts of two distinct first order U-spin breaking parameters of different origins. [Copyright &y& Elsevier]

The limits on time-reversal invariant tensor-type weak currents from nuclear and neutron γ decays are evaluated including most recent experimental data. We find that -0.14 × 10-2 < (CT + C'T)/CA < 1.4×10-2 and -0.16 < (CT - C'T)/CA < 0.16 (90% C.L.), while for the case CT = C'T the limits are 0.0 × 10-2 < CT/CA < 0.4 × 10-2. These limits are shown to be more stringent than those from recent measurements of the radiative pion decay. In addition, the sensitivity of future 10-3-level correlation measurements is investigated. [ABSTRACT FROM AUTHOR]

We review some recent progress in studying the nuclear physics especially nucleon-nucleon (NN) force within the gauge-gravity duality, in context of noncritical string theory.Our main focus is on the holographicQCDmodel based on theAdS6 background.We explain the noncritical holography model and obtain the vector-meson spectrum and pion decay constant. Also, we study the NN interaction in this frame and calculate the nucleonmeson coupling constants. A further topic covered is a toy model for calculating the light nuclei potential. In particular, we calculate the light nuclei binding energies and also excited energies of some available excited states.We compare our results with the results of other nuclear models and also with the experimental data. Moreover, we describe some other issues which are studied using the gauge-gravity duality [ABSTRACT FROM AUTHOR]

Abstract: Production of single neutrinos as well as neutrino–antineutrino pairs by photons interacting with pseudo Nambu–Goldstone bosons is studied within the Standard Model. The corresponding cross sections are found analytically. The energy loss due to neutrino emission in a thermal plasma of photons and pions is calculated. It is shown that the obtained neutrino emissivity may be significantly enhanced in hot and dense matter due to in-medium modification of the pion decay constant. Phenomenological consequences for ultrarelativistic heavy-ion collisions and astrophysics are discussed. [Copyright &y& Elsevier]

Abstract.: We evaluate the width of the ω meson in nuclear matter. We consider the free decay mode of the ω into three pions, which is dominated by ρπ decay, and replace the ρ and π propagators by their medium-modified ones. We also take into account the quasielastic and inelastic processes induced by a vector-baryon interaction dominated by vector meson exchange, as well as the contributions coming from the $ \omega\rightarrow K\bar{K}$ mechanism with medium-modified K , $ \bar{K}$ propagators. We obtain a substantial increase of the ω width in the medium, reaching a value of 121 ± 10 MeV at normal nuclear matter density for an ω at rest, which comes mainly from ωN → ππN, ωNN → πNN processes associated to the dominant ω → ρπ decay mode. The value of the width increases moderately with momentum, reaching values of around 200MeV at 600MeV/c. [ABSTRACT FROM AUTHOR]

Abstract: CP asymmetries have been measured recently by the LHCb collaboration in three-body decays to final states involving charged pions and kaons. Large asymmetries with opposite signs at a level of about have been observed in and for restricted regions in the Dalitz plots involving and with low invariant mass. U-spin is shown to predict corresponding and asymmetries with opposite signs and inversely proportional to their branching ratios, in analogy with a successful relation predicted thirteen years ago between asymmetries in and . We compare these predictions with the measured integrated asymmetries. Effects of specific resonant or non-resonant partial waves on enhanced asymmetries for low-pair-mass regions of the Dalitz plot are studied in . The closure of low-mass and channels involving only rescattering may explain by CPT approximately equal magnitudes and opposite signs measured in and . [Copyright &y& Elsevier]

A considerable fraction of Galactic supernova remnants (SNRs) characterize flat spectral indices ( α<0.5). There are several explanations of the flat radio spectra of SNRs in the present literature. The most of models involve a significant contribution of the second-order Fermi mechanism but some of them also discuss high compressions (>4), contribution of secondary electrons left over from the decay of charged pions, as well as the possibility of thermal contamination. In the case of expansion in high density environment, intrinsic thermal bremsstrahlung could theoretically shape the radio spectrum of an SNR and also account for observable curved-'concave up' radio spectra of some Galactic SNRs. This model could also shed a light on the question of flat spectral indices determined in some Galactic SNRs. On the other hand, present knowledge of the radio continuum spectra (integrated flux densities at different frequencies) of SNRs prevent definite conclusions about the significance of proposed models so the question on flat spectral indices still remains open. New observations, especially at high radio continuum frequencies, are expected to solve these questions in the near future. Finally, as there is a significant connection between the majority of Galactic SNRs with flat integrated radio spectrum and their detection in γ-rays as well as detection of radiative recombination continua in their X-ray spectra, the analysis of high energy properties of these SNRs is very important. [ABSTRACT FROM AUTHOR]

The half-skyrmions that appear in dense baryonic matter when skyrmions are put on crystals modify drastically hadron properties in dense medium and affect strongly the nuclear tensor forces, thereby influencing the equation of state (EoS) of dense nuclear and asymmetric nuclear matter. The matter comprising half-skyrmions has vanishing quark condensate but nonvanishing pion decay constant and could be interpreted as a hadronic dual of strong-coupled quark matter. We infer from this observation combined with certain predictions of hidden local symmetry in low-energy hadronic interactions a set of new scaling laws--called "new-BR"--for the parameters in nuclear effective field theory controlled by renormalization-group flow. They are subjected to the EoS of symmetric and asymmetric nuclear matter, and are then applied to nuclear symmetry energies and properties of compact stars. The changeover from the skyrmion matter to a half-skyrmion matter that takes place after the crossover density n1/2 provides a simple and natural field theoretic explanation for the change of the EoS from soft to stiff at a density above that of nuclear matter required for compact stars as massive as ~2.4M⊙ Crossover density in the range 1.5n0≤n1/288042.0n0 was employed, and the possible skyrmion half-skyrmion coexistence or crossover near n1/2 is discussed. The novel structure of the tensor forces and the EoS obtained with the new-BR scaling is relevant for neutron-rich nuclei and compact-star matter and could be studied in RIB (rare isotope beam) machines. [ABSTRACT FROM AUTHOR]

Cosmic rays are particles (mostly protons) accelerated to relativistic speeds. Despite wide agreement that supernova remnants (SNRs) are the sources of galactic cosmic rays, unequivocal evidence for the acceleration of protons in these objects is still lacking. When accelerated protons encounter interstellar material,.they produce neutral pions, which in turn decay into gamma rays. This offers a compelling way to detect the acceleration sites of protons. The identification of pion-decay gamma rays has been difficult because high-energy electrons also produce gamma rays via bremsstrahlung and inverse Compton scattering. We detected the characteristic pion-decay feature in the gamma-ray spectra of two SNRs, IC 443 and W44, with the Fermi Large Area Telescope. This detection provides direct evidence that cosmic-ray protons are accelerated in SNRs. [ABSTRACT FROM AUTHOR]

Abstract: The average formation lengths of the hadrons produced during the deep inelastic scattering (DIS) of leptons on protons are studied in the framework of the symmetric Lund model. It is shown that these formation lengths essentially depend on the electric charges of the hadron. For electro-production and charged current (CC) neutrino-production, the average formation lengths of positively charged particles are larger than those of negatively charged antiparticles. This situation is reversed for CC antineutrino-production. In all the mentioned cases, the main mechanism is the direct production of hadrons. The additional mechanism of production of hadrons, through the decay of resonances, is essential only for pions and leads to a decrease in the average formation lengths. [Copyright &y& Elsevier]

The decays J/t/f --* yir+ir∼ir° and J/i// --» yifiifitr0 are analyzed using a sample of 225 X 106 J/\¡i events collected with the BESIII detector. The decay of 77(1405) --· /0(980)7T° with a large isospin violation is observed for the first time. The width of the /0(980) observed in the dipion mass spectra is anomalously narrower than the world average. Decay rates for three-pion decays of the 7/ are also measured precisely. [ABSTRACT FROM AUTHOR]

We review the current status and future prospects of rare kaon and pion decay research programs. Our emphasis is on experimental probes of New Physics beyond the Standard Model via the theoretically pristine decays and precision tests of electron-muon universality. These studies test the Standard Model at the level of its quantum-loop predictions and have the potential to uncover new interactions beyond the O(1,000 TeV) scale. [ABSTRACT FROM AUTHOR]

Abstract: We present a model for neutrino flares in accreting black holes based on the injection of a non-thermal population of relativistic particles in a magnetized corona. The most important products of hadronic and photohadronic interactions at high energies are pions. Charged pions decay into muons and neutrinos; muons also decay yielding neutrinos. Taking into account these effects, coupled transport equations are solved for all species of particles and the neutrino production is estimated for the case of accreting galactic black holes. [Copyright &y& Elsevier]

Abstract: Particle identification in the LHCb experiment is provided by two RICH detectors, covering a momentum range of approximately 1–100GeV/c. To maintain the integrity of the LHCb physics performance, it is essential to measure and monitor the particle identification efficiency and misidentification fraction over time. To achieve this, the unique decay kinematics associated with K S 0, and decays are exploited to obtain high purity samples of pions, protons and kaons through the use of tracking information alone. Such calibration samples then allow for an unbiased assessment of the performance of the RICH detectors. Given the high production rates of K S 0, and mesons at the LHC, monitoring of the RICH detectors performance is possible both “on-line” during running and “off-line” after full-reconstruction of the data. Following analysis of the first LHC collisions, the performance of the LHCb RICH detectors will be presented based on a preliminary alignment of the detector. Identification and mis-identification probabilities as a function of track momentum will be shown. [Copyright &y& Elsevier]

Abstract: We analyze the radiative pion decay within nonlocal chiral quark models that include wave function renormalization. In this framework we calculate the vector and axial-vector form factors and at — where is the squared invariant mass — and the slope a of at . The calculations are carried out considering different nonlocal form factors, in particular those taken from lattice QCD evaluations, showing a reasonable agreement with the corresponding experimental data. The comparison of our results with those obtained in the (local) NJL model and the relation of and a with the form factor in decays are discussed. [Copyright &y& Elsevier]

Abstract: The low lying spectrum of the effective field theory is calculated in the delta-regime in 3 and 4 space–time dimensions using lattice regularization to NNL order. It allows, in particular, to determine, using numerical simulations in different spatial volumes, the pion decay constant F in QCD with 2 flavours or the spin stiffness ρ for an antiferromagnet in dimensions. [ABSTRACT FROM AUTHOR]