We evaluate differential distributions for the four-body $pp\to pp{\pi }^{+}{\pi }^{-}$ (and $p\overline{p}\to p\overline{p}{\pi }^{+}{\pi }^{-}$) reaction which constitutes an irreducible background to three-body processes $pp\to ppM$, where $M$ are a broad resonances in the ${\pi }^{+}{\pi }^{-}$ channel, e.g., $M=\sigma$, ${\rho }^0$, $f_0(980)$, $f_2(1275)$, $f_0(1500)$. We include both double-diffractive contribution (both Pomeron and Reggeon exchanges) as well as pion-pion rescattering contribution. The first process dominates at higher energies and small pion-pion invariant masses while the second becomes important at lower energies and higher pion-pion invariant masses. The amplitude(s) is(are) calculated in the Regge approach. We compare our results with measured cross sections for the Intersecting Storage Ring and Fermi National Accelerator Laboratory experiments. We make predictions for future experiments at the anti-Proton ANnihilation at DArmstadt (PANDA), Relativistic Heavy Ion Collider, Tevatron, and LHC energies. Differential distributions in invariant two-pion mass, pion rapidities and transverse momenta of pions are presented. The two-dimensional distribution in $(y_{{\pi }^{+}},y_{{\pi }^{-}})$ is particularly interesting. The higher the incident energy, the higher preference for the same-hemisphere emission of pions. The processes considered constitute a sizeable contribution to the total nucleon-nucleon cross section as well as to pion inclusive cross section.

We discuss $T$-odd correlations between jet and lepton momenta in $t\overline{t}$ events at the Tevatron that can be used to search for $CP$ violation. We identify correlations suitable for the lepton plus jets and purely hadronic top-quark pair decay channels. As an example of $CP$ violation we consider the top-quark anomalous couplings, including its chromo-electric dipole moment, and we estimate the limits that can be placed at the Tevatron.

We consider the recent measurement of the top quark forward-backward asymmetry at the Fermilab Tevatron, which shows a discrepancy of slightly more than $2\sigma$ compared to the standard model prediction. We find that $t$-channel exchange of a color sextet or triplet scalar particle can explain the measurement, while leaving the cross section for $t\overline{t}$ production within measured uncertainties. Such particles have good discovery prospects by study of the kinematic structure of $t\overline{t}+\mathrm{\text{jets}}$ at the LHC.

${\mathbb{Z}}_n$ monopoles are important for the understanding of the Goddard-Nuyts-Olive duality when the scalar field is not in the adjoint representation. We analyze the ${\mathbb{Z}}_2$ monopole solutions in $SU(n)$ Yang-Mills-Higgs theories spontaneously broken to $\mathrm{Spin}(n)/{\mathbb{Z}}_2$ by a scalar in the $n\times n$ representation. We construct explicitly ${\mathbb{Z}}_2$ monopole asymptotic fields solutions for each of the weights of the defining representation of the dual algebra $\mathrm{so}(n{)}^{\vee }$.

A new mechanism for enhancing the helium abundance in the blue main sequence stars of $\omega$ Centauri and NGC 2808 is investigated. We suggest that helium enhancement was caused by the inhomogeneous big bang nucleosynthesis. Regions with extremely high baryon-to-photon ratios are assumed to be caused by the baryogenesis. Its mass scale is also assumed to be ${10}^6{M}_{\odot }$. An example of the mechanisms to realize these two things was already proposed as the Affleck-Dine baryogenesis. As the baryon-to-photon ratio becomes larger, the primordial helium abundance is enhanced. We calculated the big bang nucleosynthesis and found that there exists a parameter region yielding enough helium to account for the split of the main sequence in the aforementioned globular clusters while keeping the abundance of other elements compatible with observations. Our mechanism predicts that heavy elements with the mass number of around 100 is enhanced in the blue main sequence stars. We estimate the time scales of diffusion of the enhanced helium and mass accretion in several stages after the nucleosynthesis to investigate whether these processes diminish the enhancement of helium. We found that the diffusion does not influence the helium content. A cloud with a sufficiently large baryon-to-photon ratio to account for the multiple main sequence collapsed immediately after the recombination. Subsequently, the cloud accreted the ambient matter with the normal helium content. If the star formation occurred both in the collapsed core and the accreted envelope, then the resultant star cluster has a double main sequence.

We investigate the $D\overline{D}$ production in $e^{+}{e}^{-}$ annihilations near threshold in an effective Lagrangian approach. This shows that the lineshape of the cross section near threshold is sensitive to the contributions from ${\psi }^{\prime }$, though it is below the $D\overline{D}$ threshold. The recent experimental data from the BES and Belle collaborations allow us to determine the ${\psi }^{\prime }D\overline{D}$ coupling constant, which appears to be consistent with other theoretical studies. As a consequence, the ${\psi }^{\prime }\mathrm{\text{−}}\psi (3770)$ mixing parameter can be extracted around the $\psi (3770)$ mass region. Resonance parameters for $\psi (3770)$, $X(3900)$, $\psi (4040)$, and $\psi (4160)$ are also investigated. The $X(3900)$ appears as an enhancement at around 3.9 GeV in the Belle data. In addition to treating it as a resonance, we also study the mechanism through which the enhancement is produced by the $D{\overline{D}}^{*}+\mathrm{c}.\mathrm{c}.$ open channel effects. Our result shows that such a possibility cannot be eliminated.

We study the effect of a right-handed coupling of quarks to the $W$-boson on the measurements of $|V_{ub}|$ and $|V_{cb}|$. It is shown that such a coupling can remove the discrepancies between the determinations of $|V_{ub}|$ from $B\to \pi \ell \nu$, $B^{+}\to {\tau }^{+}\nu$, and $B\to X_u\ell \nu$. Further the measurements of $|V_{cb}|$ from $B\to D^{*}\ell \nu$, $B\to D\ell \nu$ and inclusive $B\to X_c\ell \nu$ decays can be brought into better agreement. We demonstrate that a right-handed coupling can be generated within the minimal supersymmetric standard model by a finite gluino-squark loop. The effect involves the parameters $\delta _{23}^u{}^{RL}$ and $\delta _{13}^u{}^{RL}$ of the squark mass matrices, which are poorly constrained from other processes. On the other hand, all gluino-squark corrections to the regular left-handed coupling of the $W$-boson are found to be too small to be relevant.

Motivated by the analogy between the spacetime and the solid with inhomogeneous elasticity modulus, we present an alternative method to obtain the field equation of any diffeomorphism-invariant gravity, by extremizing the constructed entropy function of the displacement vector field of spacetime solid. In general stationary spacetimes, we show that the Wald entropy of horizon arises from the on-shell entropy function of spacetime solid.

We find spherically symmetric solutions in the modified Hořava-Lifshitz gravity proposed recently by Blas, Pujolas and Sibiryakov. The nonlinear equations of the two-derivative action turn out to be similar to those stemming from the four-derivative action explored recently. We analyze the solutions and derive constraints on the relevant new coupling constant. We also analyze the case where the cosmological constant is nonzero. We derive the large-distance expansion of solutions and show that the power of the standard Newton’s law is modified in the presence of a cosmological constant.

In Hořava-Lifshitz gravity, regularity of a solution requires smoothness of not only the spacetime geometry but also the foliation. As a result, the regularity condition at the center of a star is more restrictive than in general relativity. Assuming that the energy density is a piecewise-continuous, non-negative function of the pressure and that the pressure at the center is positive, we prove that the momentum conservation law is incompatible with the regularity at the center for any spherically symmetric, static configurations. The proof is totally insensitive to the structure of higher spatial curvature terms and, thus, holds for any values of the dynamical critical exponent $z$. Therefore, we conclude that a spherically symmetric star should include a time-dependent region near the center. This supports the picture that Hořava-Lifshitz gravity does not recover general relativity at low energy but can instead mimic general relativity plus cold dark matter: the cold dark matter accretes toward a star and thus makes the stellar center dynamical. We also comment on the condition under which linear instability of the scalar graviton does not show up.

Motivated by theoretical studies of gravitational clustering in the Universe, we compute propagators (response functions) in the adhesion model. This model, which is able to reproduce the skeleton of the cosmic web and includes nonlinear effects in both Eulerian and Lagrangian frameworks, also corresponds to the Burgers equation of hydrodynamics. Focusing on the one-dimensional case with power-law initial conditions, we obtain exact results for Eulerian and Lagrangian propagators. We find that Eulerian propagators can be expressed in terms of the one-point velocity probability distribution and show a strong decay at late times and high wave numbers, interpreted as a “sweeping effect” but not a genuine damping of small-scale structures. By contrast, Lagrangian propagators can be written in terms of the shock mass function—which would correspond to the halo mass function in cosmology—and saturate to a constant value at late times. Moreover, they show a power-law dependence on scale or wave number which depends on the initial power-spectrum index and is directly related to the low-mass tail of the shock mass function. These results strongly suggest that Lagrangian propagators are much more sensitive probes of nonlinear structures in the underlying density field and of relaxation processes than their Eulerian counterparts.

Based upon the rate equations for the photon distribution function obtained in the previous paper, we study the inverse Compton scattering process for high-energy nonthermal electrons. Assuming the power-law electron distribution, we find a scaling law in the probability distribution function $P_1(s)$, where the peak height and peak position depend only on the power-index parameter. We solved the rate equation analytically. It is found that the spectral intensity function also has the scaling law, where the peak height and peak position depend only on the power-index parameter. The present study will be particularly important to the analysis of the X-ray and gamma-ray emission models from various astrophysical objects such as radio galaxies and supernova remnants.

We provide a description of phase transitions at finite temperature in strongly coupled field theories using holography. For this purpose, we introduce a general class of gravity duals to superconducting theories that exhibit various types of phase transitions (first or second order with both mean and non-mean field behavior) as parameters in their Lagrangian are changed. Moreover the size and strength of the conductivity coherence peak can also be controlled. Our results suggest that certain parameters in the gravitational dual control the interactions responsible for binding the condensate and the magnitude of its fluctuations close to the transition.

There are few good direct laboratory tests of boost invariance for electrons, because the experiments required often involve repeated precision measurements performed at different times of the year. However, existing measurements and remeasurements of the $2S\mathrm{\text{−}}1S$ two-photon transition frequency in ${}^1\mathrm{H}$—which were done to search for a time variation in the fine structure constant—also constitute a measurement of the boost symmetry violation parameter $0.83c_{(TX)}+0.51c_{(TY)}+0.22c_{(TZ)}=(4\pm 8)\times {10}^{-11}$. This is an 8 order of magnitude improvement over preexisting laboratory bounds, and with only one additional measurement, this system could yield a second comparable constraint.

In this article, we study the vertices ${\Omega }_Q^{*}{\Omega }_Q\varphi$ with the light-cone QCD sum rules, then assume the vector meson dominance of the intermediate $\varphi (1020)$, and calculate the radiative decays ${\Omega }_Q^{*}\to {\Omega }_Q\gamma$.

We refine the relativistic constituent quark model developed in our previous papers to include the confinement of quarks. It is done, first, by introducing the scale integration in the space of $\alpha$ parameters, and, second, by cutting this scale integration on the upper limit which corresponds to an infrared cutoff. In this manner one removes all possible thresholds present in the initial quark diagram. The cutoff parameter is taken to be the same for all physical processes. We adjust other model parameters by fitting the calculated quantities of the basic physical processes to available experimental data. As an application, we calculate the electromagnetic form factors of the pion and the transition form factors of the $\omega$ and $\eta$ Dalitz decays.

We propose an effective Lagrangian for the coupling of the neutral pion with gluons whose strength is determined by a low-energy theorem. We calculate the contribution of the gluonic components arising from this interaction to the pion transition form factor ${\gamma }^{*}{\gamma }^{*}\to {\pi }^0$ using the instanton liquid model to describe the quantum chromodynamics vacuum. We find that this contribution is large and might explain the anomalous behavior of the form factor at large virtuality of one of the photons, a feature which was recently discovered by the BABAR Collaboration.

Deep inelastic scattering data on $F_2$ structure function from various fixed-target experiments were analyzed in the nonsinglet approximation with a next-to-next-to-leading-order accuracy. The study of high statistics deep inelastic scattering data provided by BCDMS, SLAC, NMC, and BFP Collaborations was carried out separately for the first one and the rest, followed by a combined analysis done as well. For the coupling constant the following value ${\alpha }_s(M_Z^2)=0.1167\pm 0.0021(\mathrm{\text{total}}\exp \mathrm{\text{error}})+\{\genfrac{}{}{0ex}{}{+0.0056}{-0.0036}(\mathrm{theor})$ was found, which in this approximation turns out to be slightly less than that obtained at the next-to-leading order, as was generally anticipated. Ditto the theoretical uncertainties reduced with respect to those obtained in the case of the next-to-leading-order analysis, thus confirming earlier observations.

A sterile neutrino with a mass of a few keV can play the role of warm dark matter (DM). This can be realized in seesaw models with 3 left- and 3 right-handed neutrinos. It is possible to identify the keV neutrino to be one of the right-handed neutrinos leaving the other two to be much more heavier, the $\nu \mathrm{SM}$ model. We show that with this realization of keV neutrino DM, the model has an approximate Friedberg-Lee symmetry providing a natural explanation for the lightness of the right-handed neutrino. We also find that in this model the mixing parameters couple light and heavy neutrinos are strongly correlated, and can be large enough to have testable effects at the LHC for the two heavy right-handed neutrinos to be in the hundred-GeV range.

We discuss neutrino oscillation physics with a neutrino factory in stages, including the possibility of upgrading the muon energy within the same program. We point out that a detector designed for the low energy neutrino factory may be used off axis in a high energy neutrino factory beam. We include the re-optimization of the experiment depending on the value of ${\theta }_{13}$ found. As upgrade options, we consider muon energy, additional baselines, a detector mass upgrade, an off-axis detector, and the platinum (muon to electron neutrino) channels. In addition, we test the impact of Daya Bay data on the optimization. We find that for large ${\theta }_{13}$ (${\theta }_{13}$ discovered by the next generation of experiments), a low energy neutrino factory might be the most plausible minimal version to test the unknown parameters. However, if a higher muon energy is needed for new physics searches, a high energy version including an off-axis detector may be an interesting alternative. For small ${\theta }_{13}$ (${\theta }_{13}$ not discovered by the next generation), a plausible program could start with a low energy neutrino factory, followed by energy upgrade, and then baseline or detector mass upgrade, depending on the outcome of the earlier phases.