We use measurements of luminosity-dependent galaxy bias at several different redshifts, SDSS at $z=0.05$, DEEP2 at $z=1$, and LBGs at $z=3.8$, combined with WMAP 5-year cosmic microwave background anisotropy data and SDSS Red Luminous Galaxy survey three-dimensional clustering power spectrum to put constraints on cosmological parameters. Fitting this combined dataset, we show that the luminosity-dependent bias data that probe the relation between halo bias and halo mass and its redshift evolution are very sensitive to sum of the neutrino masses: in particular, we obtain the upper limit of $\sum _{}^{}{m}_{\nu }<0.28\mathrm{eV}$ at the 95% confidence level for a $\Lambda \mathrm{CDM}+m_{\nu }$ model, with a ${\sigma }_8$ equal to ${\sigma }_8=0.759\pm 0.025$ ($1\sigma$). When we allow the dark energy equation-of-state parameter $w$ to vary, we find $w=-1.30\pm 0.19$ for a general $w\mathrm{CDM}+m_{\nu }$ model with the 95% confidence level upper limit on the neutrino masses at $\sum _{}^{}{m}_{\nu }<0.59\mathrm{eV}$. The constraint on the dark energy equation of state further improves to $w=-1.125\pm 0.092$ when using also ACBAR and supernovae Union data, in addition to above, with a prior on the Hubble constant from the Hubble Space Telescope.

The study of extragalactic sources of high energy radiation via the direct measurement of the proton and neutrino fluxes that they are likely to emit is one of the main goals for the future observations of the recently developed air showers detectors and neutrino telescopes. In this work we discuss the relation between the inclusive proton and neutrino signals from the ensemble of all sources in the universe and the resolved signals from the closest and brightest objects. We also compare the sensitivities of proton and neutrino telescopes and comment on the relation between these two new astronomies.

We investigate the collider signals associated with scalar quirks (squirks) in folded supersymmetric models. As opposed to regular superpartners in supersymmetric models these particles are uncolored, but are instead charged under a new confining group, leading to radically different collider signals. Because of the new strong dynamics, squirks that are pair produced do not hadronize separately, but rather form a highly excited bound state. The excited squirkonium loses energy to radiation before annihilating back into standard model particles. We calculate the branching fractions into various channels for this process, which is prompt on collider time scales. The most promising annihilation channel for discovery is $W+\mathrm{\text{photon}}$ which dominates for squirkonium near its ground state. We demonstrate the feasibility of the LHC search, showing that the mass peak is visible above the SM continuum background and estimate the discovery reach.

We examine the temperature-dependent electroweak phase transition in extensions of the standard model in which the electroweak symmetry is spontaneously broken via strongly coupled, nearly conformal dynamics. In particular, we focus on the low energy effective theory used to describe minimal walking technicolor at the phase transition. Using the one-loop effective potential with ring improvement, we identify significant regions of parameter space which yield a sufficiently strong first-order transition for electroweak baryogenesis. The composite particle spectrum corresponding to these regions can be produced and studied at the Large Hadron Collider experiment. We note the possible emergence of a second phase transition at lower temperatures. This occurs when the underlying technicolor theory possesses a nontrivial center symmetry.

We construct an effective Lagrangian for new strong interactions at the LHC, including as a first step the two lightest triplets of spin-1 resonances. Our parametrization is general enough to allow for previously unstudied spectrum and couplings. Among available frameworks to describe the spin-1 sector, we rely on an extra-dimensional description. Our approach limits the number of parameters yet is versatile enough to describe the phenomenology of a wide range of new scenarios of strong electroweak symmetry breaking.

Motivated by the recent muon $g-2$ data, we study the lepton flavor violating (LFV) $l\to l^{\prime }\gamma$ and $Z\to l{\overline{l}}^{\prime }$ ($l$, $l^{\prime }=e$, $\mu$, $\tau$ decays with $l\ne l^{\prime }$) in a scalar leptoquark model. Leptoquarks can produce sizable LFV $l\to l^{\prime }\gamma$ decay rates that can be easily reached by present or near future experiments. Leptoquark masses and couplings are constrained by the muon $g-2$ data and the current $l\to l^{\prime }\gamma$ bounds. We predict $\mathrm{Br}(Z\to {\tau }^{\mp }{e}^{\pm })$ reaching the present limit (${10}^{-5}$) and $\mathrm{Br}(Z\to {\mu }^{\mp }{\tau }^{\pm })$ reaching $2\times {10}^{-8}$, which will be accessible by future linear colliders, whereas, the current bounds on LFV impose very strong constraints on the $\mathrm{Br}(Z\to {\mu }^{\mp }{e}^{\pm })$ and the ratio is too low to be observed in the near future.

In this paper the problem of high-energy hadron-hadron (dipole-dipole) scattering is approached (for the first time) from the point of view of lattice QCD, by means of Monte Carlo numerical simulations. In the first part, we give a brief review of how high-energy scattering amplitudes can be reconstructed, using a functional-integral approach, in terms of certain correlation functions of two Wilson loops, and we also briefly recall some relevant analyticity and crossing-symmetry properties of these loop-loop correlation functions, when going from Euclidean to Minkowskian theory. In the second part, we shall see how these (Euclidean) loop-loop correlation functions can be evaluated in lattice QCD, and we shall compare our numerical results with some nonperturbative analytical estimates that appeared in the literature, discussing, in particular, the question of the analytic continuation from Euclidean to Minkowskian theory and its relation to the still unsolved problem of the asymptotic $s$ dependence of the hadron-hadron total cross sections.

We investigate the resummation of large logarithmic perturbative corrections to the partonic cross sections for single-inclusive high-$p_T$ hadron production in collisions of transversely polarized hadrons. We perform the resummation to next-to-leading logarithmic accuracy. Phenomenological results are given for $\overline{p}p$ collisions at center-of-mass energy $\sqrt{S}=14.5\mathrm{GeV}$ and for $pp$ collisions at $\sqrt{S}=62.4\mathrm{GeV}$ and at $\sqrt{S}=10\mathrm{GeV}$, which are relevant for possible experiments at the GSI-FAIR, RHIC and J-PARC facilities, respectively. We find significant enhancements of the spin-dependent and spin-averaged cross sections, but a decrease of the double-spin asymmetry $A_{TT}^{\pi }$.

The rate of the semileptonic decay $b\to c\ell \nu$ is calculated with $\mathcal{O}({\alpha }_s^2)$ accuracy, as an expansion around the limit of equal masses of the $b$ and $c$ quarks. Recent results obtained around the limit of the $c$-quark much lighter than $b$ are confirmed. Details of the new expansion method are described.

Four sets of data determining parameters of $a_0(1450)$ and $a_0(980)$ are reanalyzed. These are Crystal Barrel data for $\overline{p}p$ annihilation at rest to $\eta {\pi }^0{\pi }^0$ in (i) liquid hydrogen and (ii) gas, and to (iii) $K_L^0{\pi }^{\pm }{K}^{\mp }$ and (iv) $\omega {\pi }^{+}{\pi }^{-}{\pi }^0$ (mostly $\omega \rho \pi$). Dispersive corrections due to opening of inelastic thresholds are treated fully. This stabilizes parameters of $a_0(1450)$ substantially. The mass of its peak is $1448\pm 13(\mathrm{stat})\pm 25(\mathrm{syst})\mathrm{MeV}$ and its mean full width at half maximum is $192\pm 9\pm 9\mathrm{MeV}$. The pole position is $M-i\Gamma /2=1432\pm 13\pm 25-i(98\pm 5\pm 5)\mathrm{MeV}$. At the peak, $\eta \pi$, $\omega \rho$ and $a_0(980)\sigma$ decay intensities are in the ratios $1:9.2\pm 0.8\pm 1.3:3.1\pm 0.2\pm 0.9$. There is no evidence for a separate $a_0$ near 1300 MeV claimed by Obelix. Parameters of $a_0(980)$ are updated to $M=987.4\pm 1.0\pm 3.0\mathrm{MeV}$, $g^2(\eta \pi )=0.164\pm 0.007\pm 0.010{\mathrm{GeV}}^2$, $g^2(KK)/g^2(\eta \pi )=1.05\pm 0.07\pm 0.05$. Its dominant second-sheet pole in the $KK$ channel is at $(989\pm 1\pm 5)-i(40\pm 2\pm 4)\mathrm{MeV}$. Finally, the nature of the prominent $J^{PC}=0^{-+}\to \omega \rho$ signal in $\omega \rho \pi$ data is also clarified.

In this work, we look for possible new physics effects on the electromagnetic charge and anapole form factors, $f_Q(q^2)$ and $f_A(q^2)$, for a massless Dirac neutrino, when these quantities are calculated in the context of an effective electroweak Yang-Mills theory, which induces the most general $S{U}_L(2)$-invariant Lorentz tensor structure of nonrenormalizable type for the $WW\gamma$ vertex. It is found that in this context, besides the standard model contribution, the additional contribution to $f_Q(q^2)$ and $f_A(q^2)$ ($f_Q^{O_W}(q^2)$ and $f_A^{O_W}(q^2)$, respectively) are gauge independent and finite functions of $q^2$ after adopting a renormalization scheme. These form factors, $f_Q^{O_W}(q^2)$ and $f_A^{O_W}(q^2)$, get contribution at the one-loop level only from the proper neutrino electromagnetic vertex. Besides, the relation $f_Q^{\mathrm{eff}}(q^2)=q^2{f}_A^{\mathrm{eff}}(q^2)$ ($f_Q^{\mathrm{eff}}(q^2)=f_Q^{\mathrm{SM}}(q^2)+f_Q^{O_W}(q^2)$, $f_A^{\mathrm{eff}}(q^2)=f_A^{\mathrm{SM}}(q^2)+f_A^{O_W}(q^2)$) is still fulfilled and hence the relation $a_{\nu }^{\mathrm{eff}}=⟨r_{\nu }^2{⟩}^{\mathrm{eff}}/6$ ($a_{\nu }^{\mathrm{eff}}=a_{\nu }^{\mathrm{SM}}+a_{\nu }^{O_W}$, $⟨r_{\nu }^2{⟩}^{\mathrm{eff}}=⟨r_{\nu }^2{⟩}^{\mathrm{SM}}+⟨r_{\nu }^2{⟩}^{O_W}$) is gotten, just as in the standard model (SM). Using the experimental constraint on the anomalous $WW\gamma$ vertex, a value for the additional contribution to the charge radius of $|⟨r_{\nu }^2{⟩}^{O_W}|\lesssim {10}^{-34}{\mathrm{cm}}^2$ is obtained, which is 1 order of magnitude lower than the SM value.

We study the five-dimensional $SU(3{)}_c\times U(1{)}_C$ gauge theory on the orbifold $S^1/Z_2$ with a mixed Chern-Simons term. We particularly pay attention to the realization of the dynamical rearrangement of the theta parameter for $SU(3{)}_c$. It is shown that the physics remains invariant under a large gauge transformation which even changes the action, completely removing the theta parameter, because of the Hosotani mechanism for the $U(1{)}_C$ gauge interactions. In other words, we show that the theta parameter can be regarded as a boundary condition for the orbifolding in light of the dynamical rearrangement.

We demonstrate that the evolution of wall-like inhomogeneities in runaway potentials, characteristic of dynamical supersymmetry breaking and moduli stabilization, is very similar to the evolution of domain-wall networks associated with double-well potentials. Instabilities that would lead to a rapid decay of domain walls can be significantly ameliorated by compensation effects between a nondegeneracy of the vacua and a biased initial distribution, which can be naturally expected in a wide class or particle physics models that lead to out-of-equilibrium phase transitions. Within this framework, it is possible to obtain domain walls that live long enough to be relevant for the cosmic power spectrum and galaxy clustering, while being compatible with the observed cosmic microwave background anisotropies.

Effects of vacuum polarization by hadronic and heavy-fermion insertions were the last unknown two-loop QED corrections to high-energy Bhabha scattering and have been announced in [S. Actis, M. Czakon, J. Gluza, and T. Riemann, Phys. Rev. Lett. 100, 131602 (2008).]. Here we describe the corrections in detail and explore their numerical influence. The hadronic contributions to the virtual $\mathcal{O}({\alpha }^2)$ QED corrections to the Bhabha-scattering cross section are evaluated using dispersion relations and computing the convolution of hadronic data with perturbatively calculated kernel functions. The technique of dispersion integrals is also employed to derive the virtual $\mathcal{O}({\alpha }^2)$ corrections generated by muon-, tau-, and top-quark loops in the small electron-mass limit for arbitrary values of the internal-fermion masses. At a meson factory with 1 GeV center-of-mass energy the complete effect of hadronic and heavy-fermion corrections amounts to less than 0.5 per mille and reaches, at 10 GeV, up to about 2 per mille. At the $Z$ resonance it amounts to 2.3 per mille at 3 degrees; overall, hadronic corrections are less than 4 per mille. For ILC energies (500 GeV or above), the combined effect of hadrons and heavy fermions becomes 6 per mille at 3 degrees; hadrons contribute less than 20 per mille in the whole angular region.

Gravitational waves carry away both energy and angular momentum as binary black holes inspiral and merge. The relative efficiency with which they are radiated determines whether the final black hole of mass $M_f$ and spin $S_f$ saturates the Kerr limit (${\chi }_f\equiv S_f/M_f^2\le 1$). Extrapolating from the test-particle limit, we propose expressions for $S_f$ and $M_f$ for mergers with initial spins aligned or anti-aligned with the orbital angular momentum. We predict the the final spin at plunge for equal-mass nonspinning binaries to better than 1%, and that equal-mass maximally spinning aligned mergers lead to nearly maximally spinning final black holes (${\chi }_f\simeq 0.9988$). We also find black holes can always be spun up by aligned mergers provided the mass ratio is small enough.

Compact binaries inspiralling along eccentric orbits are plausible gravitational-wave (GW) sources for the ground-based laser interferometers. We explore the losses in the event rates incurred when searching for GWs from compact binaries inspiralling along post-Newtonian accurate eccentric orbits with certain obvious nonoptimal search templates. For the present analysis, GW signals having 2.5 post-Newtonian (PN) accurate orbital evolution are modeled following the phasing formalism, presented by T. Damour, A. Gopakumar, and B. R. Iyer [Phys. Rev. D 70, 064028 (2004)]. We demonstrate that the search templates that model in a gauge-invariant manner GWs from compact binaries inspiralling under quadrupolar radiation reaction along 2PN accurate circular orbits are very efficient in capturing our somewhat realistic GW signals. However, three types of search templates based on the adiabatic, complete adiabatic, and gauge-dependent complete nonadiabatic approximants, detailed in P. Ajith, B. R. Iyer, C. A. K. Robinson, and B. S. Sathyaprakash, Phys. Rev. D 71, 044029 (2005), relevant for the circular inspiral under the quadrupolar radiation reaction were found to be inefficient in capturing the above-mentioned eccentric signal. We conclude that further investigations will be required to probe the ability of various types of PN accurate circular templates, employed to analyze the LIGO/VIRGO data, to capture GWs from compact binaries having tiny orbital eccentricities.

We investigate field dynamics and tunneling between metastable minima in a landscape of type IIB flux compactifications, utilizing monodromies of the complex structure moduli space to continuously connect flux vacua. After describing the generic features of a flux-induced potential for the complex structure and type IIB axiodilaton, we specialize to the mirror quintic Calabi-Yau to obtain an example landscape. Studying the cosmological dynamics of the complex structure moduli, we find that the potential generically does not support slow-roll inflation and that in general the landscape separates neatly into basins of attraction of the various minima. We then discuss tunneling, with the inclusion of gravitational effects, in many-dimensional field spaces. A set of constraints on the form of the Euclidean paths through field space are presented, and then applied to construct approximate instantons mediating the transition between de Sitter vacua in the flux landscape. We find that these instantons are generically thick wall and that the tunneling rate is suppressed in the large-volume limit. We also consider examples where supersymmetry is not broken by fluxes, in which case near–Bogomolnyi-Prasad-Sommerfeld thin-wall bubbles can be constructed. We calculate the bubble-wall tension, finding that it scales like a D- or NS-brane bubble, and comment on the implications of this correspondence. Finally, we present a brief discussion of eternal inflation in the flux landscape.

The near-zero value of the cosmological constant $\Lambda$ in an equilibrium context may be due to the existence of a self-tuning relativistic vacuum variable $q$. Here, a cosmological nonequilibrium context is considered with a corresponding time-dependent cosmological parameter $\Lambda (t)$ or vacuum energy density ${\rho }_{\mathrm{V}}(t)$. A specific model of a closed Friedmann-Robertson-Walker universe is presented, which is determined by equilibrium boundary conditions at one instant of time ($t=t_{\mathrm{eq}}$) and a particular form of vacuum-energy dynamics ($d{\rho }_{\mathrm{V}}/dt\propto {\rho }_{\mathrm{M}}$). This homogeneous and isotropic model has a standard big bang phase at early times ($t\ll t_{\mathrm{eq}}$) and reproduces the main characteristics of the present universe ($t=t_0<t_{\mathrm{eq}}$).

A way to address the conundrum of quantum gravity is to illustrate the potentially fundamental interplay between quantum field theory, curved space-times physics, and thermodynamics. So far, when studying moving quantum systems in the vacuum, the only known perfectly thermal temperatures are those obtained for constant (or null) accelerations $A$ in constant (or null) Hubble parameters $H$ space-times. In this paper, restricting ourselves to conformally coupled scalar fields, we present the most comprehensive expression for the temperature undergone by a moving observer in the vacuum, valid for any time-dependent linear accelerations and Hubble parameters: $T=\sqrt{A^2+H^2+2\dot{H}\dot{t}}/2\pi$ where $\dot{t}=dt/d\tau$ is the motion’s Lorentz factor. The inequivalence between a constant $T$ and actual thermality is explained. As a byproduct, all the Friedmann universes for which observers at rest feel the vacuum as a thermal bath are listed.

Because of the noncommutation of spatial averaging and temporal evolution, inhomogeneities and anisotropies (cosmic structures) influence the evolution of the averaged Universe via the cosmological backreaction mechanism. We study the backreaction effect as a function of averaging scale in a perturbative approach up to higher orders. We calculate the hierarchy of the critical scales, at which 10% effects show up from averaging at different orders. The dominant contribution comes from the averaged spatial curvature, observable up to scales of $\sim 200\mathrm{Mpc}$. The cosmic variance of the local Hubble rate is 10% (5%) for spherical regions of radius 40 (60) Mpc. We compare our result to the one from Newtonian cosmology and Hubble Space Telescope Key Project data.