We perform a reanalysis of the production of CNO elements in a standard big bang nucleosynthesis scenario. The CNO yields in BBN are suppressed by the low density of the plasma, Coulomb barrier effects and the short time scales involved. Yet, the inclusion of nuclides and reactions traditionally disregarded may lead to an increase relevant enough to affect the pristine Population III stars. After a critical reanalysis and upgrade of the nuclear network our results show no major discrepancies with the ones obtained using a smaller nuclear network. The robustness of the standard predictions—the early generation of star developed in a metal-free environment—is confirmed.

Based on the proper-time renormalization group approach, the scalar and the quark number susceptibilities in the vicinity of possible critical end points of the hadronic phase diagram are investigated in the two-flavor quark-meson model. After discussing the quark-mass dependence of the location of such points, the critical behavior of the in-medium meson masses and quark number density are calculated. The universality classes of the end points are determined by calculating the critical exponents of the susceptibilities. In order to numerically estimate the influence of fluctuations we compare all quantities with results from a mean-field approximation. It is concluded that the region in the phase diagram where the susceptibilities are enhanced is more compressed around the critical end point if fluctuations are included.

In general relativity, the energy conditions are invoked to restrict general energy-momentum tensors $T_{\mu \nu }$ in different frameworks, and to derive general results that hold in a variety of general contexts on physical grounds. We show that in the standard Friedmann-Lemaître-Robertson-Walker (FLRW) approach, where the equation of state of the cosmological fluid is unknown, the energy conditions provide model-independent bounds on the behavior of the distance modulus of cosmic sources as a function of the redshift for any spatial curvature. We use the most recent type Ia supernovae (SNe Ia) observations, which include the new Hubble Space Telescope SNe Ia events, to carry out a model-independent analysis of the energy conditions violation in the context of the standard cosmology. We show that both the null (NEC), weak (WEC), and dominant (DEC) conditions, which are associated with the existence of the so-called phantom fields, seem to have been violated only recently ($z\lesssim 0.2$), whereas the condition for attractive gravity, i.e., the strong energy condition (SEC) was first violated billions of years ago, at $z\gtrsim 1$.

A micromechanical torsion oscillator has been used to strengthen the limits on new Yukawa forces by determining the Casimir pressure between two gold-coated plates. By significantly reducing the random errors and obtaining the electronic parameters of the gold coatings, we were able to conclusively exclude the predictions of large thermal effects below $1\mu \mathrm{m}$ and strengthen the constraints on Yukawa corrections to Newtonian gravity in the interaction range from 29.5 nm to 86 nm.

We point out a general problem with the procedures commonly used to obtain improved actions from Monte Carlo Renormalization Group (MCRG) decimated configurations. Straightforward measurement of the couplings from the decimated configurations, by one of the known methods, can result into actions that do not correctly reproduce the physics on the undecimated lattice. This is because the decimated configurations are generally not representative of the equilibrium configurations of the assumed form of the effective action at the measured couplings. Curing this involves fine-tuning of the chosen MCRG decimation procedure, which is also dependent on the form assumed for the effective action. We illustrate this in decimation studies of the $SU(2)$ lattice gauge theory using Swendsen and “double smeared blocking” decimation procedures. A single-plaquette improved action involving five group representations and nearly free of this pathology is given.

We study supersymmetric contributions to correlation coefficients that characterize the spectral shape and angular distribution for polarized $\mu$- and $\beta$-decays. In the minimal supersymmetric standard model (MSSM), one-loop box graphs containing superpartners can give rise to non-$(V-A)\otimes (V-A)$ four-fermion operators in the presence of left-right or flavor mixing between sfermions. We analyze the present phenomenological constraints on such mixing and determine the range of allowed contributions to the weak decay correlation coefficients. We discuss the prospective implications for future $\mu$- and $\beta$-decay experiments, and argue that they may provide unique probes of left-right mixing in the first generation scalar fermion sector.

Exclusive baryon pair production through the radiative return is a unique tool to determine the electric and the magnetic form factors in the timelike region over a wide range of energies. The decay of $\Lambda$-baryons into $p+{\pi }^{-}$ can be used to measure their spin and to analyze spin-spin correlations in the $\overline{\Lambda }\Lambda$ system. We evaluate the spin dependent hadronic tensor, which describes this reaction, calculate the corresponding cross section for $e^{+}{e}^{-}\to \Lambda \overline{\Lambda }$ and $e^{+}{e}^{-}\to \Lambda \overline{\Lambda }\gamma$ with subsequent decays of $\Lambda$ and $\overline{\Lambda }$ and present a compact formula for the correlated distribution. We demonstrate that the relative phase between the electric and the magnetic form factor can be determined in this analysis by considering single-spin asymmetries and correlated decay distributions. The reaction is implemented in the event generator PHOKHARA. It is demonstrated that the relative phase can be measured with the event sample presently accumulated at $B$- factories.

We examine the radiative $\Delta \to \gamma N$ transition at the real photon point $Q^2=0$ using the framework of light-cone QCD sum rules. In particular, the sum rules for the transition form factors $G_M(0)$ and $R_{EM}$ are determined up to twist 4. The result for $G_M(0)$ agrees with experiment within 10% accuracy. The agreement for $R_{EM}$ is also reasonable. In addition, we derive new light-cone sum rules for the magnetic moments of nucleons, with a complete account of twist-4 corrections based on a recent reanalysis of photon distribution amplitudes.

We show how theoretical, principally lattice calculations of the scalar form factors in semileptonic pseudoscalar-to-pseudoscalar decays can be used to extract information about the corresponding elastic $s$-wave scattering channels. We find values for the scattering lengths $m_{\pi }a=0.179(17)(14)$, 0.26(26) and 0.29(4) for elastic $s$-wave isospin-$1/2$ $K\pi$, $B\pi$ and $D\pi$ channels, respectively. We also determine phase shifts. For the $DK$ channel we find hints that there is a bound state which can be identified with the recently discovered $D_{s0}^{+}(2317)$.

In the framework of the electroweak chiral Lagrangian, the one-loop induced effects of the anomalous $tbW$ coupling, which includes both left- and right-handed complex components, on the static electromagnetic properties of the $W$ boson and the $t$ quark are studied. The attention is focused mainly on the $CP$-violating electromagnetic properties. It is found that the $tbW$ anomalous coupling can induce both $CP$-violating moments of the $W$ boson, namely, its electric dipole (${\tilde{\mu }}_W$) and magnetic quadrupole (${\tilde{Q}}_W$) moments. As far as the $t$ quark is concerned, a potentially large electric dipole moment ($d_t$) can arise due to the anomalous $tbW$ coupling. The most recent bounds on the $tbW$ coupling left- and right-handed parameters from $B$ meson physics lead to the following estimates ${\tilde{\mu }}_W\sim 4\times {10}^{-23}-4\times {10}^{-22}\mathrm{e}·\mathrm{cm}$ and ${\tilde{Q}}_W\sim {10}^{-38}-{10}^{-37}\mathrm{e}·{\mathrm{cm}}^2$, which are 7 and 14 orders of magnitude larger than the standard model (SM) predictions, whereas $d_t$ may be as large as ${10}^{-22}\mathrm{e}·\mathrm{cm}$, which is about 8 orders of magnitude larger than its SM counterpart.

We investigate the magnetic dipole decays $V\to P\gamma$ of various heavy-flavored mesons such as $(D,D^{*},D_s,D_s^{*},{\eta }_c,J/\psi )$ and $(B,B^{*},B_s,B_s^{*},{\eta }_b,{\rm Y})$ using the light-front quark model constrained by the variational principle for the QCD-motivated effective Hamiltonian. The momentum dependent form factors $F_{VP}(q^2)$ for $V\to P{\gamma }^{*}$ decays are obtained in the $q^{+}=0$ frame and then analytically continued to the timelike region by changing ${\mathbf{q}}_{\perp }$ to $i{\mathbf{q}}_{\perp }$ in the form factors. The coupling constant $g_{VP\gamma }$ for real photon case is then obtained in the limit as $q^2\to 0$, i.e. $g_{VP\gamma }=F_{VP}(q^2=0)$. The weak decay constants of heavy pseudoscalar and vector mesons are also calculated. Our numerical results for the decay constants and radiative decay widths for the heavy-flavored mesons are overall in good agreement with the available experimental data as well as other theoretical model calculations.

Following the holographic description of linear dilaton null cosmologies with a big bang in terms of matrix string theory put forward by Craps, Sethi, and Verlinde, we propose an extended background describing a universe including both big bang and big crunch singularities. This belongs to a class of exact string backgrounds and is perturbative in the string coupling far away from the singularities, both of which can be resolved using matrix string theory. We provide a simple theory capable of describing the complete evolution of this closed universe.

Based on the description of unstable $K_{L,S}$ particles in quantum field theory (QFT), we compute the time-dependent probabilities for transitions between asymptotic states in ${\tau }^{\pm }\to [{\pi }^{+}{\pi }^{-}{]}_K{\pi }^{\pm }\nu$ decays, where the pair $[{\pi }^{+}{\pi }^{-}{]}_K$ is the product of (intermediate state) neutral kaon decays. Then we propose a definition of $\tau$ decays into $K_L$ and $K_S$ states, which reflects into the cancellation between their $CP$ rate asymmetries, thus solving in a natural way the paradox pointed out in [I. I. Bigi and A. I. Sanda, Phys. Lett. B 625, 47 (2005).]. Since our definition of $K_{L,S}$ final states in $\tau$ decays is motivated on experimental grounds, our predictions for the integrated $CP$ rate asymmetries can be tested in a dedicated experiment.

A phenomenological analysis of the three-family model based on the local gauge group $SU(3{)}_c\otimes SU(3{)}_L\otimes U(1{)}_X$ with exotic charged leptons, is carried out. Instead of using the minimal scalar sector able to break the symmetry in a proper way, we introduce an alternative set of four Higgs scalar triplets, which combined with an anomaly-free discrete symmetry, produce quark and charged lepton mass spectrum without hierarchies in the Yukawa coupling constants. We also embed the structure into a simple gauge group and show some conditions to achieve a low energy gauge coupling unification, avoiding possible conflict with proton decay bounds. By using experimental results from the CERN-LEP, SLAC linear collider, and atomic parity violation data, we update constraints on several parameters of the model.

The discrete flavor symmetry $A_4$ explains very well neutrino data at low energy, but it seems difficult to extend it to grand unified models since, in general, left-handed and right-handed fields belong to different $A_4$ representations. Recently a model has been proposed where all the fermions equally transform under $A_4$. We study here a concrete $SO(10)$ realization of such a model providing small neutrino masses through the see-saw mechanism. We fit the charged fermion masses run up to the unification scale. Some fermion masses properties come from the $SO(10)$ symmetry while lepton mixing angles are a consequence of the $A_4$ properties. Moreover, our model predicts the absolute value of the neutrino masses; these are in the range $m_{\nu }\simeq 0.005–0.052\mathrm{eV}$.

In order to extract the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ from $B\to X_{u}l{\overline{\nu }}_l$ decays, the overwhelming background from $B\to X_{c}l{\overline{\nu }}_l$ decays must be reduced by appropriate acceptance cuts. We study the nonperturbative effects due to the motion of the $b$ quark inside the $B$ meson on the phenomenologically relevant decay distributions of $B\to X_{u}l{\overline{\nu }}_l$ in the presence of such cuts in a comparative analysis based on shape functions and the parton model in the light cone limit. Comparisons with recent data from the CLEO, BABAR, and BELLE collaborations favor the shape-function approach.

We present results from a simulation of quenched overlap fermions with Lüscher-Weisz gauge field action on lattices up to ${24}^{3}48$ and for pion masses down to $\approx 250\mathrm{MeV}$. Among the quantities we study are the pion, rho, and nucleon masses; the light and strange quark masses; and the pion decay constant. The renormalization of the scalar and axial vector currents is done nonperturbatively in the RI-MOM scheme. The simulations are performed at two different lattice spacings, $a\approx 0.1\mathrm{fm}$ and $\approx 0.15\mathrm{fm}$, and on two different physical volumes, to test the scaling properties of our action and to study finite volume effects. We compare our results with the predictions of chiral perturbation theory and compute several of its low-energy constants. The pion mass is computed in sectors of fixed topology as well.

We consider the possibility of getting accelerated expansion and $w=-1$ crossing in the context of a braneworld cosmological setup, endowed with a bulk energy-momentum tensor. For a given ansatz of the bulk content, we demonstrate that the bulk pressures dominate the dynamics at late times and can lead to accelerated expansion. We also analyze the constraints under which we can get a realistic profile for the effective equation of state and conclude that matter in the bulk has the effect of dark energy on the brane. Furthermore, we show that it is possible to simulate the behavior to a Chaplygin gas using nonexotic bulk matter.

We study baryons in holographic QCD with $\mathrm{D}4/\mathrm{D}8/\overline{\mathrm{D}8}$ multi-D-brane system. In holographic QCD, the baryon appears as a topologically nontrivial chiral soliton in a four-dimensional effective theory of mesons. We call this topological soliton brane-induced Skyrmion. Some review of $\mathrm{D}4/\mathrm{D}8/\overline{\mathrm{D}8}$ holographic QCD is presented from the viewpoints of recent hadron physics and QCD phenomenologies. A four-dimensional effective theory with pions and $\rho$ mesons is uniquely derived from the non-Abelian Dirac-Born-Infeld (DBI) action of D8 brane with D4 supergravity background at the leading order of large $N_c$, without small amplitude expansion of meson fields to discuss chiral solitons. For the hedgehog configuration of pion and $\rho$-meson fields, we derive the energy functional and the Euler-Lagrange equation of brane-induced Skyrmion from the meson effective action induced by holographic QCD. Performing the numerical calculation, we obtain the soliton solution and figure out the pion profile $F(r)$ and the $\rho$-meson profile $\tilde{G}(r)$ of the brane-induced Skyrmion with its total energy, energy density distribution, and root-mean-square radius. These results are compared with the experimental quantities of baryons and also with the profiles of standard Skyrmion without $\rho$ mesons. We analyze interaction terms of pions and $\rho$ mesons in brane-induced Skyrmion, and find a significant $\rho$-meson component appearing in the core region of a baryon.