The importance and signatures of cosmic tau (anti)neutrinos have been studied for upward- and downward-going ${\mu }^{-}+{\mu }^{+}$ and hadronic shower event rates relevant for present and future underground water or ice detectors, utilizing the unique and reliable ultrasmall-$x$ predictions of the dynamical (radiative) parton model. The upward-going ${\mu }^{-}+{\mu }^{+}$ event rates calculated just from cosmic ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ fluxes are sizably enhanced by taking into account cosmic ${\nu }_{\tau }+{\overline{\nu }}_{\tau }$ fluxes and their associated ${\tau }^{-}+{\tau }^{+}$ fluxes as well. The coupled transport equations for the upward-going ${\stackrel{(-)}{\nu }}_{\tau }$ flux traversing the Earth imply an enhancement of the attenuated and regenerated ${\stackrel{(-)}{\nu }}_{\tau }$ flux typically around ${10}^4–{10}^5\mathrm{GeV}$ with respect to the initial cosmic flux. This enhancement turns out to be smaller than obtained so far, in particular, for flatter initial cosmic fluxes behaving like $E_{\nu }^{-1}$. Downward-going ${\mu }^{-}+{\mu }^{+}$ events and, in particular, the background-free and unique hadronic “double bang” and “lollipop” events allow one to test downward-going cosmic ${\nu }_{\tau }+{\overline{\nu }}_{\tau }$ fluxes up to about ${10}^9\mathrm{GeV}$.

We present a Dalitz-plot analysis of charmless $B^{\pm }$ decays to the final state ${\pi }^{\pm }{\pi }^{\pm }{\pi }^{\mp }$ using $210{\mathrm{fb}}^{-1}$ of data recorded by the BABAR experiment at $\sqrt{s}=10.58\mathrm{GeV}$. We measure the branching fractions $\mathcal{B}({\mathrm{B}}^{\pm }\to {\pi }^{\pm }{\pi }^{\pm }{\pi }^{\mp })=(16.2\pm 1.2\pm 0.9)\times {10}^{-6}$ and $\mathcal{B}(B^{\pm }\to {\rho }^0(770){\pi }^{\pm })=(8.8\pm 1.0\pm {0.6}_{-0.7}^{+0.1})\times {10}^{-6}$. Measurements of branching fractions for the quasi-two-body decays $B^{\pm }\to {\rho }^0(1450){\pi }^{\pm }$, $B^{\pm }\to {\mathrm{f}}_0(980){\pi }^{\pm }$ and $B^{\pm }\to {\mathrm{f}}_2(1270){\pi }^{\pm }$ are also presented. We observe no charge asymmetries for the above modes, and there is no evidence for the decays $B^{\pm }\to {\chi }_{c0}{\pi }^{\pm }$, $B^{\pm }\to {\mathrm{f}}_0(1370){\pi }^{\pm }$ and $B^{\pm }\to \sigma {\pi }^{\pm }$.

In a previous paper [1] we constructed wave functions of a D-instanton and vertex operators in type IIB matrix model by expanding supersymmetric Wilson line operators. They describe couplings of a D-instanton and type IIB matrix model to the massless closed string fields, respectively, and form a multiplet of $D=10$ $\mathcal{N}=2$ supersymmetries. In this paper we consider fermionic backgrounds and condensation of supergravity fields in IIB matrix model by using these wave functions. We start from the type IIB matrix model in a flat background whose matrix size is $(N+1)\times (N+1)$, or equivalently the effective action for $(N+1)$ D-instantons. We then calculate an effective action for $N$ D-instantons by integrating out 1 D-instanton (which we call a mean-field D-instanton) with an appropriate wave function and show that various terms can be induced corresponding to the choice of the wave functions. In particular, a Chern-Simons-like term is induced when the mean-field D-instanton has a wave function of the antisymmetric tensor field. A fuzzy sphere becomes a classical solution to the equation of motion for the effective action. We also give an interpretation of the above wave functions in the superstring theory side as overlaps of the D-instanton boundary state with the closed string massless states in the Green-Schwarz formalism.

The current accelerated universe could be produced by modified gravitational dynamics as it can be seen, in particular, in its Palatini formulation. We analyze here a specific nonlinear gravity-scalar system in the first-order Palatini formalism which leads to a Friedmann-Robertson-Walker cosmology different from the purely metric one. It is shown that the emerging Friedmann-Robertson-Walker cosmology may lead either to an effective quintessence phase (cosmic speed-up) or to an effective phantom phase. Moreover, the already known gravity assisted dark energy dominance occurs also in the first-order formalism. Finally, it is shown that a dynamical theory able to resolve the cosmological constant problem exists also in this formalism, in close parallel with the standard metric formulation.

It is pointed out that in the warped string compactification, motion of $\overline{D}$-branes near the bottom of a throat behaves like dark matter. Several scenarios for production of the dark matter are suggested, including one based on the $D/\overline{D}$ interaction at the late stage of $D/\overline{D}$ inflation.

Recent improvements in the low energy $e^{+}{e}^{-}$ annihilation data and their influence on the determination of the hadronic contribution to the running of the QED fine structure constant at $m_Z$ are discussed. Using CMD-2 and KLOE measurements in the $\rho$ region we obtain $\Delta {\alpha }_{\mathrm{had}}^{(5)}(s)=0.02758\pm 0.00035$ at $s=m_Z^2$.

We explore the physics potential of the NuMI beamline with a detector located 10 km off axis at a distant site (810 km). We study the sensitivity to ${sin}^{2}2{\theta }_{13}$ and to the $CP$-violating parameter $\sin \delta$ as well as the determination of the neutrino mass hierarchy by exploiting the ${\nu }_{\mu }\to {\nu }_e$ and ${\overline{\nu }}_{\mu }\to {\overline{\nu }}_e$ appearance channels. The results are illustrated for three different experimental setups to quantify the benefits of increased detector sizes, proton luminosities, and ${\nu }_e$ detection efficiencies.

We present a study of the production of $K_S^0$ and ${\Lambda }^0$ in inelastic $p\overline{p}$ collisions at $\sqrt{s}=1800$ and 630 GeV using data collected by the CDF experiment at the Fermilab Tevatron. Analyses of $K_S^0$ and ${\Lambda }^0$ multiplicity and transverse momentum distributions, as well as of the dependencies of the average number and $⟨p_T⟩$ of $K_S^0$ and ${\Lambda }^0$ on charged particle multiplicity, are reported. Systematic comparisons are performed for the full sample of inelastic collisions, and for the low and high momentum transfer subsamples, at the two energies. The $p_T$ distributions extend above $8\mathrm{GeV}/c$, showing a $⟨p_T⟩$ higher than previous measurements. The dependence of the mean $K_S^0({\Lambda }^0)$ $p_T$ on the charged particle multiplicity for the three samples shows a behavior analogous to that of charged primary tracks.

We report an unexpected theoretical discovery of a spin one-half matter field with mass dimension one. It is based on a complete set of eigenspinors of the charge conjugation operator. Because of its unusual properties with respect to charge conjugation and parity, it belongs to a nonstandard Wigner class. Consequently, the theory exhibits nonlocality with $(CPT{)}^2=-\mathbb{I}$. Its dominant interaction with known forms of matter is via Higgs, and with gravity. This aspect leads us to contemplate it as a first-principle candidate for dark matter.

We study the renormalization problem for the Hartree-Fock approximation of the $O(N)$ invariant ${\varphi }^4$ model in the symmetric phase and show how to systematically improve the corresponding diagrammatic resummation to achieve the correct renormalization properties of the effective field equations, including renormalization-group invariance with the one-loop beta function. These new Hartree-Fock dynamics is still of a mean-field type but includes memory effects which are generically nonlocal also in space.

In this paper, we raised the question of whether initial cosmological singularity can be proven by cosmological tests. The classical general relativity theory predicts the existence of singularity in the past if only some energy conditions are satisfied. On the other hand, the latest quantum gravity applications to cosmology suggest the possibility of avoiding the singularity and replacing it with a bounce. Bounce is the moment in the evolution of the Universe when the Universe’s size is minimum. Therefore the existence of observationally detected bounce in the Universe’s past could indicate the validity of the loop quantum gravity hypothesis and nonexistence of initial singularity which is present in the classical $\Lambda \mathrm{CDM}$. We investigated the bouncing model described by the generalized Friedmann-Robertson-Walker equation in the context of the observations of the currently accelerating universe. The distant type Ia supernovae data are used to constrain the bouncing evolutional scenario where the square of the Hubble function $H^2$ is given by the formula $H^2=H_0^2[{\Omega }_{m,0}(1+z{)}^m-{\Omega }_{n,0}(1+z{)}^n]$, where ${\Omega }_{m,0},{\Omega }_{n,0}>0$ are density parameters and $n>m>0$. In this paper are shown that, on the basis of the SNIa data, standard bouncing models can be ruled out at the $4\sigma$ confidence level. After adding the cosmological constant to the standard bouncing model (the extended bouncing model), we obtained as the best fit that the parameter ${\Omega }_{n,0}$ is equal to zero which means that the SNIa data do not support the bouncing term in the model. The bouncing term is statistically insignificant on the present epoch. We also demonstrated that BBN offers the possibility of obtaining stringent constraints of the extra term ${\Omega }_{n,0}$. The other observational test methods like CMB and the age of oldest objects in the Universe are also used. We use as well the Akaike informative criterion to select a model which best fits data and we concluded that the bouncing term should be ruled out by Occam’s razor, which makes the big-bang scenario more favorable than the bouncing scenario.

We propose a novel approach to the problem of constraining cosmological initial conditions. Within the framework of effective field theory, we classify initial conditions in terms of boundary terms added to the effective action describing the cosmological evolution below Planckian energies. These boundary terms can be thought of as spacelike branes which may support extra instantaneous degrees of freedom and extra operators. Interactions and renormalization of these boundary terms allow us to apply to the boundary terms the field-theoretical requirement of naturalness, i.e. stability under radiative corrections. We apply this requirement to slow-roll inflation with nonadiabatic initial conditions, and to cyclic cosmology. This allows us to define in a precise sense when some of these models are fine-tuned. We also describe how to parametrize in a model-independent way non-Gaussian initial conditions; we show that in some cases they are both potentially observable and pass our naturalness requirement.

We consider the electroweak radiative corrections in the minimal supersymmetric standard model and study the purely Yukawa contributions $\mathcal{O}({\alpha }^L{y}_t^{2p}{y}_b^{2q})$, $p+q=L$, where $y_{t,b}$ are the top and bottom quark Yukawa couplings. We show that these corrections can be computed in a gaugeless limit of the minimal supersymmetric standard model where they are under renormalization group control. As an application, we present explicit results for various international linear collider and LHC processes valid at all orders in the loop expansion and at leading order in the large logarithms that arise at high energy.

We present an alternative to the standard model with unitary gauge group $U(N{)}^p$ and chiral fermions in bifundamentals. Although the construction allows scalars in adjoints and bifundamentals, only models without adjoint scalars have strikingly, without supersymmetry, absence of one-loop quadratic divergence in the scalar propagator. Decisive support for these ideas could arise from new experimental results anticipated at the LHC proton collider.

The severe constraints imposed on the parameter space of the minimal split supersymmetry model by the infrared fixed point solution of the top Yukawa coupling $Y_t$ are studied in detail in terms of the value of the top-quark mass measured at the Tevatron together with the lower bound on the lightest Higgs mass established by LEP. The dependence of the Higgsino mass parameter $\mu$, the gaugino coupling strengths ${\tilde{g}}_{u,d}$, ${\tilde{g}}_{u,d}^{\prime }$ and of the Higgs quartic self-coupling $\lambda$ on the value of $Y_t$ in the vicinity of the Landau pole is discussed. A few interesting features emerge, though the model is found to be disfavored within the infrared fixed point scenario because of the need to have several unnatural cancellations at work on account of the requirement of a low upper bound on $\tan \beta$.

We investigate theories in which the technifermions in higher dimensional representations of the technicolor gauge group dynamically break the electroweak symmetry of the standard model. Somewhat surprisingly, for the two-index symmetric representation of the gauge group the lowest number of techniflavors needed to render the underlying gauge theory quasiconformal is two. This is exactly one doublet of technifermions with respect to the weak interactions promoting these theories to ideal candidates of walking type technicolor models. From the point of view of the weak interactions the two techniflavor theory has a Witten anomaly, which we cure by introducing a fourth family of leptons. An elegant feature of this model is that the techniquarks resemble an extra family of quarks arranged in the two-index symmetric representation of the SU(2) technicolor theory. We have also studied the theory with three technicolors and two techniflavors in the two-index symmetric representation of the gauge group, which does not require a fourth family of leptons. We confront the models with the recent electroweak precision measurements and demonstrate that the two technicolor theory is a valid candidate for electroweak symmetry breaking via new strong interactions. We investigate different hypercharge assignments for the two color theory and associated fourth family type of leptons. We find that the two technicolor theory is within the 90% confidence level contours defined by the oblique parameters. The electroweak precision measurements provide useful constraints on the relative mass splitting of the new leptons. In the case of a fourth family of leptons with ordinary lepton hypercharge the new heavy neutrino can be a natural candidate of cold dark matter. The mass of this heavy neutrino, constrained by the precision measurements, is slightly larger than the one of the neutral electroweak gauge boson while the charged lepton has a mass roughly twice as large as the associated neutrino. Extensions with a larger value of the hypercharge naturally featuring doubly charged leptons are also favored by precision measurements. We also propose theories in which the critical number of flavors needed to enter the conformal window is higher than the one with fermions in the two-index symmetric representation, but lower than in the walking technicolor theories with fermions only in the fundamental representation of the gauge group. The simplest theories are the ones in which we add a (techni)gluino to the theory, while the rest of the matter fermions remain in the fundamental representation of the gauge group. Although these theories share some features with split supersymmetric theories, they are introduced here to address the hierarchy problem. Because of the near-conformal/chiral phase transition, we show that the composite Higgs is very light compared to the intrinsic scale of the technicolor theory. For the two technicolor theory we predict the composite Higgs mass not to exceed 150 GeV. We also provide estimates for the Higgs mass in walking technicolor theories with fermions in the fundamental representation and show that in this case the mass is around 400 GeV.

We present results from simulations of two flavors of dynamical overlap fermions on $8^4$ lattices at three values of the sea quark mass and a lattice spacing of about 0.16 fm. We measure the topological susceptibility and the chiral condensate. A comparison of the low-lying spectrum of the overlap operator with predictions from random matrix theory is made. To demonstrate the effect of the dynamical fermions, we compare meson two-point functions with quenched results. Algorithmic improvements over a previous publication and the performance of the algorithm are discussed.

We present calculations of the prompt photon photoproduction at HERA collider in the $k_T$-factorization approach. Both direct and resolved contributions are taken into account. The conservative error analisys is performed. The unintegrated parton densities in a proton and in a photon are determined using the Kimber-Martin-Ryskin prescription. We investigate both inclusive and associated with jet prompt photon photoproduction rates. In particular, we study the angular correlations between produced photon and hadronic jet in the transverse momentum plane which can provide a unique information about noncollinear evolution dynamics. We compare our theoretical predictions with recent experimental data taken by the H1 and ZEUS collaborations.

Establishing the neutrino mass hierarchy is one of the fundamental questions that will have to be addressed in the near future. Its determination could be obtained with long-baseline experiments but typically suffers from degeneracies with other neutrino parameters. We consider here the $\mathrm{NO}\nu \mathrm{A}$ experiment configuration and propose to place a second off-axis detector, with a shorter baseline, such that, by exploiting matter effects, the type of neutrino mass hierarchy could be determined with only the neutrino run. We show that the determination of this parameter is free of degeneracies, provided the ratio $L/E$, where $L$ is the baseline and $E$ is the neutrino energy, is the same for both detectors.