We report on the first search for atmospheric and for diffuse astrophysical neutrino-induced showers (cascades) in the IceCube detector using 257 days of data collected in the year 2007–2008 with 22 strings active. A total of 14 events with energies above 16 TeV remained after event selections in the diffuse analysis, with an expected total background contribution of $8.3\pm 3.6$. At 90% confidence we set an upper limit of $E^2{\Phi }_{90\%\mathrm{CL}}<3.6\times {10}^{-7}\mathrm{GeV}·{\mathrm{cm}}^{-2}·{\mathrm{s}}^{-1}·s{r}^{-1}$ on the diffuse flux of neutrinos of all flavors in the energy range between 24 TeV and 6.6 PeV assuming that $\Phi \propto E^{-2}$ and the flavor composition of the ${\nu }_e:{\nu }_{\mu }:{\nu }_{\tau }$ flux is $1:1:1$ at the Earth. The atmospheric neutrino analysis was optimized for lower energies. A total of 12 events were observed with energies above 5 TeV. The observed number of events is consistent with the expected background, within the uncertainties.

After incorporating $f(R)$ gravity into the general braneworld sum rules scope, it is shown that some particular class of warped five-dimensional nonlinear braneworld models, which may be interesting for the hierarchy problem solution, still require a negative tension brane. For other classes of warp factors (suitable and not suitable for approaching the hierarchy problem) any negative brane tension in the compactification scheme is not necessary. In this vein, it is argued that, in the bulk $f(R)$ gravity context, some types of warp factors may be useful for approaching the hierarchy problem and for evading the necessity of a negative brane tension in the compactification scheme.

Fractionally charged massive particles (FCHAMPs) appear in extensions of the standard model, especially those with superstring constructions. The lightest FCHAMP would be absolutely stable and any of them produced during the early evolution of the Universe would be present today. The thermal production, annihilation and, survival of an FCHAMP, a lepton $L$ with electroweak (i.e., $U(1{)}_Y$) but no strong interactions, of mass $m_L$ and charge $Q_L$ (in units of the charge on the electron) are explored. The FCHAMP relic abundance is determined by the total annihilation cross section which depends on $m_L$, $Q_L$ and on the available annihilation channels. Since massive ($m_L\gtrsim 1\mathrm{GeV}$) charged particles ($Q_L\gtrsim 0.01$) behave like baryons (heavy ions), primordial nucleosynthesis and the cosmic background radiation temperature anisotropies limit the FCHAMP relic density. Requiring that ${\Omega }_L\lesssim {\Omega }_{\mathrm{B}}/5$ leads to a constraint on the $Q_L-m_L$ relation. Further constraints on $Q_L$ and $m_L$ are provided by the invisible width of the $Z$ ($Q_L>0.16$ for $m_L\le M_Z/2$) and by accelerator searches for massive, charged particles. Our key result is to exploit the fact that in the early Universe, after $L^{\pm }$ freeze-out but prior to $e^{\pm }$ recombination, the negatively charged $L^{-}$ will combine with the more abundant alpha particles and protons to form tightly bound, positively charged states (fractionally charged heavy ions). The Coulomb barriers between these positively charged $L^{-}\alpha$ and $L^{-}p$ ($L^{-}pp$, $L^{-}\alpha \alpha$, …) bound states and the free $L^{+}$ suppresses late-time FCHAMP annihilation in the interstellar medium (ISM) of the Galaxy and on Earth, limiting significantly the late-time reduction of the FCHAMP abundance compared to its relic value. The surviving FCHAMP abundance on Earth is orders of magnitude higher than the limits from terrestrial searches for fractionally charged particles, closing the window on FCHAMPs with $Q_L\gtrsim 0.01$. However, as $Q_L$ approaches an integer (e.g., $|Q_L-n|\lesssim 0.25$) these searches become increasingly insensitive, leaving some potentially unconstrained “islands” in the $Q_L-m_L$ plane which may be explored by searching for FCHAMPs in the cosmic rays.

In recent years, the Gribov-Zwanziger action was refined by taking into account certain dimension 2 condensates. In this fashion, one succeeded in bringing the gluon and the ghost propagator obtained from the Gribov-Zwanziger model in qualitative and quantitative agreement with the lattice data. In this paper, we shall elaborate further on this aspect. First, we shall show that more dimension 2 condensates can be taken into account than considered so far and, in addition, we shall give firm evidence that these condensates are in fact present by discussing the effective potential. It follows thus that the Gribov-Zwanziger action dynamically transforms itself into the refined version, thereby showing that the continuum nonperturbative Landau gauge fixing, as implemented by the Gribov-Zwanziger approach, is consistent with lattice simulations.

A class of projective actions of the orthogonal group on the projective space is being studied. It is shown that the Fock-Lorentz and Magueijo-Smolin transformations known as doubly special relativity are such transformations. The formalism easily leads to new types of transformations.

Spherically symmetric, time-periodic oscillatons—solutions of the Einstein-Klein-Gordon system (a massive scalar field coupled to gravity) with a spatially localized core—are investigated by very precise numerical techniques based on spectral methods. In particular, the amplitude of their standing-wave tail is determined. It is found that the amplitude of the oscillating tail is very small, but nonvanishing for the range of frequencies considered. It follows that exactly time-periodic oscillatons are not truly localized, and they can be pictured loosely as consisting of a well (exponentially) localized nonsingular core and an oscillating tail making the total mass infinite. Finite mass physical oscillatons with a well localized core—solutions of the Cauchy-problem with suitable initial conditions—are only approximately time-periodic. They are continuously losing their mass because the scalar field radiates to infinity. Their core and radiative tail is well approximated by that of time-periodic oscillatons. Moreover the mass loss rate of physical oscillatons is estimated from the numerical data and a semiempirical formula is deduced. The numerical results are in agreement with those obtained analytically in the limit of small amplitude time-periodic oscillatons.

We investigate finite-size effects on the chiral transition at finite temperature and density in the framework of the Nambu-Jona-Lasinio model in the presence of an external magnetic field. The thermodynamic potential and the gap equation are derived in the mean-field approximation and analyzed under the changing of the relevant parameters.

Exact relations on the existence of event horizons of Myers-Perry black holes are obtained in $D\le 10$ dimensions. It is further shown that naked singularities cannot be produced by “spinning-up” these black holes by shooting particles into their $\lfloor \frac{D-1}{2}\rfloor$ equatorial planes.

Motivated by the recent argument that in the TeV-scale gravity trans-Planckian domains of spacetime as effective naked singularities would be generated by high-energy particle (and black hole) collisions, we investigate the quantum particle creation by naked-singularity formations in general dimensions. Background spacetime is simply modeled by the self-similar Vaidya solution, describing the spherical collapse of a null dust fluid. In a generic case, the emission power is found to be proportional to the quadratic inverse of the remaining time to a Cauchy horizon, as known in four dimensions. On the other hand, the power is proportional to the quartic inverse for a critical case in which the Cauchy horizon is “degenerate.” According to these results, we argue that the backreaction of the particle creation to gravity will be important in particle collisions, in contrast to the gravitational collapse of massive stellar objects, since the bulk of energy is carried away by the quantum radiation even if a quantum gravitational effect cutoff the radiation just before the appearance of a naked singularity.

In this article, we construct spherical thin-shell wormholes with charge in dilaton gravity. The exotic matter required for the construction is provided by a generalized Chaplygin gas. We study the stability under perturbations preserving the symmetry. We find that the increase of the coupling between the dilaton and the electromagnetic fields reduces the range of the parameters for which stable configurations are possible.

By setting some special boundary conditions in the variational principle we obtain junction conditions for the five-dimensional $f(R)$ gravity that in the Einstein limit $f(R)\to R$ transform into the standard Randall-Sundrum junction conditions. We apply these junction conditions to a particular model of a Friedmann universe on the brane and show explicitly that the limit gives the standard Randall-Sundrum model Friedmann equation.

We develop a Lagrangian approach based on the influence functional method so as to derive self-consistently the Langevin equation for the inflaton field in the presence of trapping points along the inflaton trajectory. The Langevin equation exhibits the backreaction and the fluctuation-dissipation relation of the trapping. The fluctuation is induced by a multiplicative colored noise that can be identified as the particle number density fluctuations; and the dissipation is a new effect that may play a role in the trapping with a strong coupling. In the weak coupling regime, we calculate the power spectrum of the noise-driven inflaton fluctuations for a single trapping point and studied its variation with the trapping location. We also consider a case with closely spaced trapping points and find that the resulting power spectrum is blue.

A plasma-kinetic model to properly describe the behavior of neutrons in the primordial plasma during the epoch of big bang nucleosynthesis (BBN) is formulated. For the first time, this model is applied to calculate the realistic energy distribution function of these neutrons and examine their main characteristics. The fact that the realistic neutron distribution departs from a conventional Maxwellian function is obtained; its high-energy tail is essentially enhanced by nonthermal neutrons produced in the $\mathrm{T}(d,n{)}^4\mathrm{He}$ and $\mathrm{D}(d,n{)}^3\mathrm{He}$ reactions. The fraction of these neutrons ${\eta }_n^{\prime }$ in the total neutron component is at a level of ${10}^{-2}\%–{10}^{-3}\%$, while their effective temperature $T_n^{\prime }$ reaches several MeV and exceeds the plasma temperature in the BBN epoch by about a factor of ${10}^2$. The nonthermal neutron influence on individual reactions is examined on the example of the threshold $\mathrm{D}(n,2n)p$, ${}^7\mathrm{Li}(n,nt){}^4\mathrm{He}$, and ${}^7\mathrm{Be}(n,n{}^3\mathrm{He}){}^4\mathrm{He}$ processes. We show that at plasma temperatures $T_9\lesssim 1.2$ the nonthermal neutrons strongly maintain these reactions, increasing their rates by orders of magnitude as compared with the respective Maxwellian estimates. Note that the obtained phenomenon has a general nature. It may manifest in other nuclear systems and becomes a natural supplement of nonthermal effects triggered by dark matter decay, which has been extensively studied elsewhere. An important question remains—to what extent such fast particles may affect chain reaction kinetics in the plasma and change the predictions of standard BBN.

Gravitational wave astronomy has tremendous potential for studying extreme astrophysical phenomena and exploring fundamental physics. The waves produced by binary black hole mergers will provide a pristine environment in which to study strong-field dynamical gravity. Extracting detailed information about these systems requires accurate theoretical models of the gravitational wave signals. If gravity is not described by general relativity, analyses that are based on waveforms derived from Einstein’s field equations could result in parameter biases and a loss of detection efficiency. A new class of “parameterized post-Einsteinian” waveforms has been proposed to cover this eventuality. Here, we apply the parameterized post-Einsteinian approach to simulated data from a network of advanced ground-based interferometers and from a future space-based interferometer. Bayesian inference and model selection are used to investigate parameter biases, and to determine the level at which departures from general relativity can be detected. We find that in some cases the parameter biases from assuming the wrong theory can be severe. We also find that gravitational wave observations will beat the existing bounds on deviations from general relativity derived from the orbital decay of binary pulsars by a large margin across a wide swath of parameter space.

We use a consistent SU(6) extension of the meson-baryon chiral Lagrangian within a coupled channel unitary approach in order to calculate the $T$ matrix for meson-baryon scattering in the $s$ wave. The building blocks of the scheme are the $\pi$ and $N$ octets, the $\rho$ nonet and the $\Delta$ decuplet. We identify poles in this unitary $T$ matrix and interpret them as resonances. We study here the nonexotic sectors with strangeness $S=0$, $-1$, $-2$, $-3$ and spin $J=\frac{1}{2}$, $\frac{3}{2}$ and $\frac{5}{2}$. Many of the poles generated can be associated with known $N$, $\Delta$, $\Sigma$, $\Lambda$, $\Xi$ and $\Omega$ resonances with negative parity. We show that most of the low-lying three and four star odd-parity baryon resonances with spin $\frac{1}{2}$ and $\frac{3}{2}$ can be related to multiplets of the spin-flavor symmetry group SU(6). This study allows us to predict the spin-parity of the $\Xi (1620)$, $\Xi (1690)$, $\Xi (1950)$, $\Xi (2250)$, $\Omega (2250)$ and $\Omega (2380)$ resonances, which have not been determined experimentally yet.

We present a contemporary perspective on the String Landscape and the Multiverse of plausible string, $M$- and $F$-theory vacua. In contrast to traditional statistical classifications and capitulation to the anthropic principle, we seek only to demonstrate the existence of a nonzero probability for a universe matching our own observed physics within the solution ensemble. We argue for the importance of No-Scale Supergravity as an essential common underpinning for the spontaneous emergence of a cosmologically flat universe from the quantum “nothingness.” Concretely, we continue to probe the phenomenology of a specific model which is testable at the LHC and Tevatron. Dubbed No-Scale $\mathcal{F}\mathrm{\text{−}}SU(5)$, it represents the intersection of the Flipped $SU(5)$ Grand Unified Theory (GUT) with extra TeV-Scale vectorlike multiplets derived out of $F$-theory, and the dynamics of No-Scale Supergravity, which in turn imply a very restricted set of high-energy boundary conditions. By secondarily minimizing the minimum of the scalar Higgs potential, we dynamically determine the ratio $\tan \beta \simeq 15–20$ of up- to down-type Higgs vacuum expectation values (VEVs), the universal gaugino boundary mass $M_{1/2}\simeq 450\mathrm{GeV}$, and, consequently, also the total magnitude of the GUT-scale Higgs VEVs, while constraining the low-energy standard model gauge couplings. In particular, this local minimum minimorum lies within the previously described “golden strip,” satisfying all current experimental constraints. We emphasize, however, that the overarching goal is not to establish why our own particular universe possesses any number of specific characteristics, but rather to tease out what generic principles might govern the superset of all possible universes.

We present a discussion of light charged Higgs boson searches at the Large Hadron Collider (LHC) in $CP$-conserving 2-Higgs doublet models (2HDMs). Taking into account all available experimental and theoretical constraints we review all possible processes that would allow for a detection of such a particle with a mass below the top quark mass. Such experimental constraints restrict the number of 2HDMs where a light charged Higgs is allowed to two. Two different types of processes are analyzed: one that depends only on $\tan \beta$ and on the charged Higgs boson mass because it involves only the charged Higgs boson Yukawa couplings; the other that depends on almost all model parameters, mainly due to the presence of Higgs self-couplings. We discuss the regions of parameter space of 2HDMs that can be covered by each type of process and define some guidelines for experimental searches at the LHC.

The conventional series in powers of the coupling in perturbative QCD have zero radius of convergence and fail to reproduce the singularity of the QCD correlators like the Adler function at ${\alpha }_s=0$. Using the technique of conformal mapping of the Borel plane, combined with the “softening” of the leading singularities, we define a set of new expansion functions that resemble the expanded correlator and share the same singularity at zero coupling. Several different conformal mappings and different ways of implementing the known nature of the first branch-points of the Adler function in the Borel plane are investigated, in both the contour-improved (CI) and fixed-order (FO) versions of renormalization-group resummation. We prove the remarkable convergence properties of a set of new CI expansions and use them for a determination of the strong coupling from the hadronic $\tau$-decay width. By taking the average upon this set, with a conservative treatment of the errors, we obtain ${\alpha }_s(M_{\tau }^2)={0.3195}_{-0.0138}^{+0.0189}$.

The measurement of the top forward-backward asymmetry in $t\overline{t}$ production measured at the Tevatron shows deviation from the standard model prediction. A $u\to t$ transition via a flavor-changing $Z^{\prime }$ can explain the data. We show that left-handed $t_L{u}_L{Z}^{\prime }$ couplings can be constrained from $B_{d,s}$ mixing while the constrains on the right-handed couplings $t_R{u}_R{Z}^{\prime }$ vanish in the limit of $m_u\to 0$. We then consider the most general form of the $tu{Z}^{\prime }$ interaction which includes vector-axial vector as well as tensor type couplings and study how these couplings affect the top forward-backward asymmetry.

We present a study of $B_s^0$ decays to the $CP$-odd final state $J/\psi f_0(980)$ with $J/\psi \to {\mu }^{+}{\mu }^{-}$ and $f_0(980)\to {\pi }^{+}{\pi }^{-}$. Using $p\overline{p}$ collision data with an integrated luminosity of $3.8{\mathrm{fb}}^{-1}$ collected by the CDF II detector at the Tevatron we measure a $B_s^0$ lifetime of $\tau (B_s^0\to J/\psi f_0(980))={1.70}_{-0.11}^{+0.12}(\mathrm{stat})\pm 0.03(\mathrm{syst})\mathrm{ps}$. This is the first measurement of the $B_s^0$ lifetime in a decay to a $CP$ eigenstate and corresponds in the standard model to the lifetime of the heavy $B_s^0$ eigenstate. We also measure the product of branching fractions of $B_s^0\to J/\psi f_0(980)$ and $f_0(980)\to {\pi }^{+}{\pi }^{-}$ relative to the product of branching fractions of $B_s^0\to J/\psi \varphi$ and $\varphi \to K^{+}{K}^{-}$ to be $R_{f_0/\varphi }=0.257\pm 0.020(\mathrm{stat})\pm 0.014(\mathrm{syst})$, which is the most precise determination of this quantity to date.