The analysis of the recent charged-current neutrino-nucleus scattering cross sections measured by the MiniBooNE Collaboration requires relativistic theoretical descriptions also accounting for the role of final-state interactions. In this work, we evaluate differential antineutrino-nucleus cross sections with the relativistic Green’s function model, where the final-state interactions are described in the inclusive scattering consistently with the exclusive scattering using a complex optical potential. The sensitivity to the parameterization adopted for the phenomenological optical potential is discussed. The predictions of the relativistic Green’s function model are compared with the results of different descriptions of final-state interactions.

We consider a $U(4)$ Yang-Mills theory on $\mathcal{M}\times S_F^2\times S_F^2$ where $\mathcal{M}$ is an arbitrary Riemannian manifold and $S_F^2\times S_F^2$ is the product of two fuzzy spheres spontaneously generated from a $SU(\mathcal{N})$ Yang-Mills theory on $\mathcal{M}$ which is suitably coupled to six scalars in the adjoint of $U(\mathcal{N})$. We determine the $SU(2)\times SU(2)$-equivariant $U(4)$ gauge fields and perform the dimensional reduction of the theory over $S_F^2\times S_F^2$. The emergent model is a $U(1{)}^4$ gauge theory coupled to four complex and eight real scalar fields. We study this theory on ${\mathbb{R}}^2$ and find that, in certain limits, it admits vortex type solutions with $U(1{)}^3$ gauge symmetry and discuss some of their properties.

Eternal inflation is a seemingly generic consequence of theories that give rise to accelerated expansion of the universe and possess multiple vacuum states. Making predictions in an eternally inflating universe is notoriously difficult because one must compare infinite quantities, and a wide variety of regulating procedures yield radically different results. This is the measure problem of eternal inflation. In this paper, we analyze models of eternal inflation which allow for the possibility of cyclic bubble universes: in each bubble, standard cosmological evolution is replayed over and over again. Eternal inflation can generically arise in cyclic models that include a dark energy dominated phase. In such models, several problematic consequences of certain regulating procedures, such as the youngness and Boltzmann brain problems, are substantially alleviated. We discuss the implications for making predictions in cyclic models, as well as some general implications for understanding the measure problem in eternal inflation.

We consider the process of primordial black hole (PBH) formation originated from primordial curvature perturbations produced during waterfall transition (with tachyonic instability), at the end of hybrid inflation. It is known that in such inflation models, rather large values of curvature perturbation amplitudes can be reached, which can potentially cause a significant PBH production in the early Universe. The probability distributions of density perturbation amplitudes in this case can be strongly non-Gaussian, which requires a special treatment. We calculated PBH abundances and PBH mass spectra for the model and analyzed their dependence on model parameters. We obtained the constraints on the parameters of the inflationary potential, using the available limits on ${\beta }_{\mathrm{PBH}}$.

The existence of inhomogeneities in the observed Universe modifies the distance-redshift relations thereby affecting the results of cosmological tests in comparison to the ones derived assuming spatially uniform models. By modeling the inhomogeneities through a Zeldovich-Kantowski-Dyer-Roeder approach which is phenomenologically characterized by a smoothness parameter $\alpha$, we rediscuss the constraints on the cosmic parameters based on type Ia supernovae (SNe Ia) and gamma-ray bursts (GRBs) data. The present analysis is restricted to a flat $\Lambda \mathrm{CDM}$ model with the reasonable assumption that $\Lambda$ does not clump. A ${\chi }^2$ analysis using 557 SNe Ia data from the Union2 compilation data (R. Amanullah et al., Astrophys. J. 716, 712 (2010).) constrains the pair of parameters (${\Omega }_m$, $\alpha$) to ${\Omega }_m={0.27}_{-0.03}^{+0.08}$ ($2\sigma$) and $\alpha \ge 0.25$. A similar analysis based only on 59 Hymnium GRBs (H. Wei, J. Cosmol. Astropart. Phys. 08 (2010) 020.) constrains the matter density parameter to be ${\Omega }_m={0.35}_{-0.24}^{+0.62}$ ($2\sigma$) while all values for the smoothness parameter are allowed. By performing a joint analysis, it is found that ${\Omega }_m={0.27}_{-0.03}^{+0.06}$ and $\alpha \ge 0.52$. As a general result, although considering that current GRB data alone cannot constrain the smoothness $\alpha$ parameter, our analysis provides an interesting cosmological probe for dark energy even in the presence of inhomogeneities.

We discuss flavor mixing and resulting flavorchanging neutral current in a five-dimensional $SU(3{)}_{\mathrm{color}}\otimes SU(3)\otimes U^{\prime }(1)$ gauge-Higgs unification. Flavor mixing is realized by the fact that the bulk and brane-localized mass terms are not diagonalized simultaneously. As the concrete flavor-changing neutral current processes, we calculate the rate of $B_d^0-{\overline{B}}_d^0$ mixing and $B_s^0-{\overline{B}}_s^0$ mixing due to the exchange of nonzero Kaluza-Klein gluons at the tree level. We obtain a lower bound on the compactification scale of order $\mathcal{O}(\mathrm{TeV})$ by comparing our prediction on the mass difference of neutral $B$ meson with the recent experimental data.

We investigate whether or not perturbative unitarity is preserved in the unHiggs model for the scattering process of heavy quarks and longitudinal gauge bosons $\overline{q}q\to V_L^{+}{V}_L^{-}$. With the Yukawa coupling given in the original formulation of the unHiggs model, the model preserves unitarity for unHiggs scaling dimensions $d\le 1.5$. We examine the LHC phenomenology which is implied by the unHiggs model in this parameter range in detail and discuss to what extent the LHC can test $d$ if an excess is measured in the phenomenologically clean $ZZ$ channel in the future or if the LHC measurement remains consistent with the background. We then make use of the AdS/CFT correspondence to derive a new Yukawa coupling which is conformally invariant at high energies and show that with this Yukawa coupling, the theory is unitary for $1\le d<2$.

We reanalyze the radial ($n$) and angular-momentum ($J$) Regge trajectories for all light-quark states with baryon number zero listed in the 2011 edition of the Particle Data tables. The parameters of the trajectories are obtained with linear regression, with weight of each resonance inversely proportional to its half-width squared, $(\Gamma /2)2$. That way, we are side-stepping possible channel-dependent and model-dependent extractions of the resonance parameters and are able to undertake an error analysis. The method complies to the fact that the pole position of the resonance is typically shifted from channel-dependent extractions by $\sim \Gamma /2$. This is also a feature of the large-$N_c$ limit of QCD, where the masses change by $\Gamma /2$ when evolving from $N_c=3$ to $N_c=\infty$. Our value for the slope of the radial Regge trajectories is $a=1.35\left(4\right){\mathrm{GeV}}^2$. We discuss the fundamental issue whether the masses of the light-quark nonstrange states fit into a universal pattern $M_{nJ}^2=a(n+J)+b$, as suggested by Afonin, and also predicted by some holographic models. Our joint linear-regression analysis in the $(n,J,M^2)$ Regge planes indicates, at a statistically significant level of 4.5 standard deviations, that the slopes of the radial Regge trajectories are larger from the angular-momentum slopes. Thus, no strict universality of slopes occurs in the light nonstrange meson spectra.

The paper contains a systematic, model-independent treatment of electric dipole (E1) transitions in heavy quarkonium. Within the effective field theory framework of potential nonrelativistic QCD, we derive the complete set of relativistic corrections of relative order $v^2$ both for weakly and strongly coupled quarkonia. The result supports and complements former results from potential model calculations.

The rare decays $B_s\to {\mu }^{+}{\mu }^{-}$ and $B\to K^{(*)}{\mu }^{+}{\mu }^{-}$ are sensitive to new particles and couplings via their interferences with the standard model contributions. Recently, the upper bound on $\mathcal{B}(B_s\to {\mu }^{+}{\mu }^{-})$ has been improved significantly by the CMS, LHCb, CDF, and D0 experiments. Combining with the measurements of $\mathcal{B}(B\to K^{(*)}{\mu }^{+}{\mu }^{-})$, we derive constraints on the relevant parameters of the minimal supersymmetic standard model with and without $R$ parity, and examine their contributions to the dimuon forward-backward asymmetry in $B\to K^{*}{\mu }^{+}{\mu }^{-}$ decay. We find that (i) the contribution of $R$-parity violating coupling products ${\lambda }_{2i2}^{\prime }{\lambda }_{2i3}^{\prime *}$ due to squark exchange is comparable with the theoretical uncertainties in $B\to K{\mu }^{+}{\mu }^{-}$ decay, but still could be significant in $B\to K^{*}{\mu }^{+}{\mu }^{-}$ decay and could account for the forward-backward asymmetry in all dimuon invariant mass regions; (ii) the constrained mass insertion $({\delta }_{LL}^u{)}_{23}$ could have a significant contribution to $d{\mathcal{A}}_{\mathrm{FB}}(B\to K^{*}{\mu }^{+}{\mu }^{-})/ds$, and such effects are favored by the recent results of the Belle, CDF, and LHCb experiments.

The precision measurement of the mass of the $W$ boson is an important goal of the Fermilab Tevatron and the CERN Large Hadron Collider (LHC). It requires accurate theoretical calculations which incorporate both higher-order QCD and electroweak corrections, and also provide an interface to parton-shower Monte Carlo programs which make it possible to realistically simulate experimental data. In this paper, we present a combination of the full $\mathcal{O}(\alpha )$ electroweak corrections of wgrad2, and the next-to-leading order QCD radiative corrections to $W\to \ell \nu$ production in hadronic collisions in a single event generator based on the powheg framework, which is able to interface with the parton-shower Monte Carlo programs pythia and herwig. Using this new combined QCD + EW Monte Carlo program for $W$ production, we provide numerical results for total cross sections and kinematic distributions of relevance to the $W$ mass measurement at the Tevatron and the LHC for the processes $pp$, $p\overline{p}\to W^{\pm }\to {\mu }^{\pm }{\nu }_{\mu }$. In particular, we discuss the impact of EW corrections in the presence of QCD effects when including detector resolution effects.

We repurpose the recent ATLAS search for same-sign top quarks in data with $1.0{\mathrm{fb}}^{-1}$ in the context of a search for production of four top quarks. Using the null results of that search, we place limits on the four-top-quark production cross section of about 1 pb. These limits are larger than the expected standard model rate for four-top-quark production, but are already strong enough to place interesting constraints on models which enhance that rate. We interpret these results in the context of models in which the right-handed top quark is composite and find limits on the compositeness scale of about 700 GeV.

A study of $B^{\pm }\to J/\psi {\pi }^{\pm }$ and $B^{\pm }\to \psi (2S){\pi }^{\pm }$ decays is performed with data corresponding to $0.37{\mathrm{fb}}^{-1}$ of proton-proton collisions at $\sqrt{s}=7\mathrm{TeV}$. Their branching fractions are found to be $\mathcal{B}(B^{\pm }\to J/\psi {\pi }^{\pm })=(3.88\pm 0.11\pm 0.15)\times {10}^{-5}\mathrm{\text{and}}\mathcal{B}(B^{\pm }\to \psi (2S){\pi }^{\pm })=(2.52\pm 0.26\pm 0.15)\times {10}^{-5},$where the first uncertainty is related to the statistical size of the sample and the second quantifies systematic effects. The measured $CP$ asymmetries in these modes are $A_{CP}^{J/\psi \pi }=0.005\pm 0.027\pm 0.011\mathrm{\text{and}}{A}_{CP}^{\psi (2S)\pi }=0.048\pm 0.090\pm 0.011$ with no evidence of direct $CP$ violation seen.

We discuss a new interacting model for the cosmological dark sector in which the attenuated dilution of cold dark matter scales as $a^{-3}f(a)$, where $f(a)$ is an arbitrary function of the cosmic scale factor $a$. From thermodynamic arguments, we show that $f(a)$ is proportional to the entropy source of the particle creation process. In order to investigate the cosmological consequences of this kind of interacting models, we expand $f(a)$ in a power series, and viable cosmological solutions are obtained. Finally, we use current observational data to place constraints on the interacting function $f(a)$.

We consider the dynamics of a strongly coupled $\mathrm{SU}(N)$ chiral gauge theory. By using its large-$N$ equivalence with $\mathcal{N}=1$ super-Yang-Mills theory we find the vacuum structure of the former. We also consider its finite-$N$ dynamics.

Any conformal field theory (CFT) on a sphere supports completely undamped collective oscillations. We discuss the implications of this fact for studies of thermalization using AdS/CFT. Analogous oscillations occur in Galilean CFT, and they could be observed in experiments on ultracold fermions.

We study the energy-momentum pseudotensor of gravitational waves, and examine the one introduced by Landau-Lifshitz for a general gravitational field and the effective one recently used in literature. In the short-wavelength limit after the Brill-Hartle average, both lead to the same gauge-invariant stress tensor of gravitational waves. For relic gravitational waves in the expanding universe, we examine two forms of pressure, $p_{\mathrm{gw}}$ and ${\mathcal{P}}_{\mathrm{gw}}$, and trace the origin of their difference to a coupling between gravitational waves and the background matter. The difference is shown to be negligibly small for most cosmic expansion stages starting from inflation. We demonstrate that the wave equation is equivalent to the energy-conservation equation using the pressure ${\mathcal{P}}_{\mathrm{gw}}$ that includes the mentioned coupling.

We investigate the effects of the underlying quantum geometry in loop quantum cosmology on spacetime curvature invariants and the extendibility of geodesics in the Bianchi-I model for matter with a vanishing anisotropic stress. Using the effective Hamiltonian approach, we find that even though quantum geometric effects bound the energy density and expansion and shear scalars, divergences of curvature invariants are potentially possible under special conditions. However, as in the isotropic models in LQC, these do not necessarily imply a physical singularity. Analysis of geodesics and strength of such singular events, point towards a general resolution of all known types of strong singularities. We illustrate these results for the case of a perfect fluid with an arbitrary finite equation of state $w>-1$, and show that curvature invariants turn out to be bounded, leading to the absence of strong singularities. Unlike classical theory, geodesic evolution does not break down. We also discuss possible generalizations of sudden singularities which may arise at a nonvanishing volume, causing a divergence in curvature invariants. Such finite volume singularities are shown to be weak and harmless.

We derive the relativistic kinetic equation for Compton scattering of polarized radiation in strong magnetic field using the Bogolyubov method. The induced scattering and the Pauli exclusion principle are taken into account. The electron polarization is also considered in the general form of the kinetic equation. The special forms of the equation for the cases of the nonpolarized electrons, the rarefied electron gas and the two-polarization mode description of radiation are found. The derived equations are valid for any photon and electron energies and the magnetic field strength below about ${10}^{16}\mathrm{G}$. These equations provide the basis for formulation of the equation for polarized radiation transport in atmospheres and magnetospheres of strongly magnetized neutron stars.

We study a simple extension of the standard model where the gauge group is extended by an additional $U(1{)}_X$ gauge symmetry. Neutrino mass arises both at tree level as well as radiatively by the anomaly-free addition of one singlet fermion $N_R$ and two triplet fermions ${\Sigma }_{1R}$, ${\Sigma }_{2R}$ with suitable Higgs scalars. The spontaneous gauge symmetry breaking is achieved in a way that results in a residual $Z_2$ symmetry and hence provides a stable cold dark matter candidate. We study the possible dark matter candidates in this model by incorporating the constraints from cosmology as well as direct detection experiments. We discuss both low- and high-mass (from GeV to the TeV scale) regimes of fermionic and scalar dark matter candidates in the model. We show that scalar dark matter relic density, although not significantly affected by the presence or absence of annihilation into $U(1{)}_X$ gauge boson pairs, is however affected by choice of $U(1{)}_X$ gauge charges. We discuss the neutrino mass phenomenology and its compatibility with the allowed dark matter mass ranges and we also comment on the implications of the model on Higgs signatures at colliders including those related to the fourth fermion generation.