We consider the possibility of the Higgs mechanism in the bulk in a generalized Randall-Sundrum model, where a nonvanishing cosmological constant is induced on the visible brane. This scenario has the advantage of accommodating positive tension of the visible brane and thus ensures stability of the model. It is shown that several problems usually associated with this mechanism are avoided if some dimensionful parameters in the bulk are allowed to lie a little below the Planck mass. The most important of these is keeping the lowest massive mode in the scale of the standard electroweak model, and at the same time reducing the gauge coupling of the next excited state, thus ameliorating otherwise stringent phenomenological constraints.

We show that respecting the underlying Lorentz structure in the parton model has very strong consequences. Failure to insist on the correct Lorentz covariance is responsible for the existence of contradictory results in the literature for the polarized structure function $g_2(x)$, whereas with the correct imposition we are able to derive the Wandzura-Wilczek relation for $g_2(x)$ and the target-mass corrections for polarized deep inelastic scattering without recourse to the operator product expansion. We comment briefly on the problem of threshold behavior in the presence of target-mass corrections. Careful attention to the Lorentz structure has also profound implications for the structure of the transverse momentum dependent parton densities often used in parton model treatments of hadron production, allowing the ${\mathit{k}}_T$ dependence to be derived explicitly. It also leads to stronger positivity and Soffer-type bounds than usually utilized for the collinear densities.

We consider constraints from flavor physics on two-Higgs-doublet models (2HDM) with general, flavor-diagonal, Yukawa couplings. Analyzing the charged Higgs contribution to different observables, we find that $b\to s\gamma$ transitions and $\Delta M_{B_d}$ restrict the coupling ${\lambda }_{tt}$ of the top quark (corresponding to $\cot \beta$ in models with a $Z_2$ symmetry) to $|{\lambda }_{tt}|<1$ for $m_{H^{+}}\lesssim 500\mathrm{GeV}$. Stringent constraints from $B$ meson decays are obtained also on the other third generation couplings ${\lambda }_{bb}$ and ${\lambda }_{\tau \tau }$, but with stronger dependence on $m_{H^{+}}$. For the second generation, we obtain constraints on combinations of ${\lambda }_{ss}$, ${\lambda }_{cc}$, and ${\lambda }_{\mu \mu }$ from leptonic $K$ and $D_s$ decays. The limits on the general couplings are translated to the common 2HDM types I–IV with a $Z_2$ symmetry, and presented on the $(m_{H^{+}},\tan \beta )$ plane. The flavor constraints are most excluding in the type II model which lacks a decoupling limit in $\tan \beta$. We obtain a lower limit $m_{H^{+}}\gtrsim 300\mathrm{GeV}$ in models of type II and III, while no lower bound on $m_{H^{+}}$ is found for types I and IV.

We study a class of nonsupersymmetric $SO(10)$ grand-unified scenarios where the first stage of the symmetry breaking is driven by the vacuum expectation values of the 45-dimensional adjoint representation. Three-decade-old results claim that such a Higgs setting may lead exclusively to the flipped $SU(5)\otimes U(1)$ intermediate stage. We show that this conclusion is actually an artifact of the tree-level potential. The study of the accidental global symmetries emerging in various limits of the scalar potential offers a simple understanding of the tree-level result and a rationale for the drastic impact of quantum corrections. We scrutinize in detail the simplest and paradigmatic case of the ${45}_H\oplus {16}_H$ Higgs sector triggering the breaking of $SO(10)$ to the standard electroweak model. We show that the minimization of the one-loop effective potential allows for intermediate $SU(4{)}_C\otimes SU(2{)}_L\otimes U(1{)}_R$ and $SU(3{)}_c\otimes SU(2{)}_L\otimes SU(2{)}_R\otimes U(1{)}_{B-L}$ symmetric stages as well. These are the options favored by gauge unification. Our results, that apply whenever the $SO(10)$ breaking is triggered by $⟨{45}_H⟩$, open the path for hunting the simplest realistic scenario of nonsupersymmetric $SO(10)$ grand unification.

We extract the Boer-Mulders functions for the proton by combining the unpolarized $pd$ and $pp$ Drell-Yan data measured by the E866/NuSea Collaboration by the assumption that the $\cos 2\varphi$ asymmetry is from the Boer-Mulders functions. Using the extracted Boer-Mulders functions, we present the predictions for the $\cos 2\varphi$ asymmetries in future $pp$ experiments at J-PARC and $p\overline{p}$ experiments at PANDA and PAX.

We consider the possibility that sterile neutrinos exist and admit a description as unparticles; we call these unsterile neutrinos. We then examine the nature of neutrino oscillations in a model where an unsterile can mix with two active flavors with a very simple mass matrix of the seesaw type. Despite these simplifications, we find a number of remarkable features, all of which will occur generically when more realistic cases are considered. These include momentum dependent mixing angles, invisible decay widths for the unsterile-like mode, as well as the inheritance of a nonvanishing spectral density for the massive activelike modes. We also obtain the disappearance and appearance probabilities for the activelike neutrinos and find remarkable interference effects between the active and unsterile neutrinos as a consequence of threshold effects, yielding new oscillatory contributions with different oscillation lengths. These effects are only measurable on short baseline experiments because there both probabilities are suppressed as compared to mixing with a canonical sterile neutrino, thereby providing a diagnostics tool to discriminate unsterile from canonical sterile neutrinos. We conclude with a discussion of whether these new phenomena could aid in the reconciliation of the LSND and MiniBooNE results.

The distributions of the quark number and chiral condensate over the gauge fields are computed for QCD in Euclidean space at nonzero quark chemical potential. As both operators are non-Hermitian the distributions are in the complex plane. Moreover, because of the sign problem, the distributions are not real and positive. The computations are carried out within leading order chiral perturbation theory and give a direct insight into the delicate cancellations that take place in contributions to the total baryon number and the chiral condensate.

In this paper, a new quantum mechanical method to extract energy from black holes with contracting horizons is proposed. The method is based on a gedanken experiment on quantum energy teleportation, which has been recently proposed in quantum information theory. We consider this quantum energy teleportation protocol for $N$ massless fields in near-horizon regions of large-mass black holes with near-horizon geometry described by the Minkowski metric. For each field, a two-level spin is strongly coupled with the local quantum fluctuation outside the horizon during a short time period. After the measurement of $N$ fields, $N$-bit information is obtained. During the measurement, positive-energy wave packets of the fields form and then fall into the black hole. The amount of excitation energy is independent of the measurement result. After absorption of the wave packets and increase of the black-hole mass, a measurement-result-dependent local operation of the $N$ fields is performed outside the horizon. Then, accompanying the extraction of positive energy from the quantum fluctuation by the operation, negative-energy wave packets of the fields form and then fall into the black hole, decreasing the black-hole mass. This implies that a part of the absorbed positive energy emitted from the measurement devices is effectively retrieved from the black hole via the measurement results.

We investigate the linear growth rate of cosmological matter density perturbations in a viable $f(R)$ model both numerically and analytically. We find that the growth rate in the scalar-tensor regime can be characterized by a simple analytic formula. We also investigate a prospect of constraining the Compton wavelength scale of the $f(R)$ model with a future weak lensing survey.

We explore the stability of domain wall and bubble solutions in theories with compact extra dimensions. The energy density stored inside of the wall can destabilize the volume modulus of a compactification, leading to solutions containing either a timelike singularity or a region where space decompactifies, depending on the metric ansatz. We determine the structure of such solutions both analytically and using numerical simulations, and analyze how they arise in compactifications of Einstein-Maxwell theory and type IIB string theory. The existence of instabilities has important implications for the formation of networks of topological defects and the population of vacua during eternal inflation.

The generation of primordial magnetic seed fields during inflation is studied in a theory derived from the one-loop vacuum polarization effective action of the photon in a curved background. This includes terms which couple the curvature to the Maxwell tensor. The resulting magnetic field strength is estimated in a model where the inflationary phase is directly matched to the standard radiation dominated era. The allowed parameter region is analyzed and compared with the bounds necessary to seed the galactic magnetic field. It is found that magnetic fields of cosmologically interesting field strengths can be generated.

To reduce the thermal noise in the future generation of gravitational wave detectors, flat-top beams have been proposed to replace conventional Gaussian beams, so as to obtain better averaging over the Brownian motion of the test masses. Here, we present a detailed investigation of the unwanted opto-acoustic interactions in such interferometers, which can lead to the phenomenon of parametric instability. Our results show that the increased overlap of the Mesa beams with the test masses leads to approximately 3 times as many unstable modes in comparison to a similar interferometer with Gaussian beams.

Introducing a noncompact version of the Hopf map, we demonstrate remarkable close relations between quantum Hall effect and twistor theory. We first construct quantum Hall effect on a hyperboloid based on the noncompact 2nd Hopf map of split-quaternions. We analyze a hyperbolic one-particle mechanics, and explore many-body problem, where a many-body ground state wave function and membrane-like excitations are derived explicitly. In the lowest Landau level, the symmetry is enhanced from $SO(3,2)$ to the $SU(2,2)$ conformal symmetry. We point out that the quantum Hall effect naturally realizes the philosophy of twistor theory. In particular, emergence mechanism of fuzzy space-time is discussed somehow in detail.

We have studied the mass hierarchy with atmospheric neutrinos considering the muon energy and zenith angle of the event at the magnetized iron calorimeter detector. For ${\chi }^2$ analysis we have migrated the number of events from neutrino energy and zenith angle bins to muon energy and zenith angle bins using the two-dimensional energy-angle correlated resolution functions. Then the ${\chi }^2$ is marginalized considering all possible systematic uncertainties of the atmospheric neutrino flux and cross section. The effects of the ranges of oscillation parameters on the marginalization are also studied. The lower limit of the range of ${\theta }_{13}$ for marginalization is found to be very crucial in determining the sensitivity of hierarchy for a given ${\theta }_{13}$. Finally, we show that one can discriminate atmospheric neutrino mass hierarchy at $>90\%$ C.L. if the lower limit of ${\theta }_{13}\ge 5°$.

We reexamine the prospects for the detection of Higgs-mediated lepton flavor violation at LHC, at a photon collider and in $\tau$ decays such as $\tau \to \mu \eta$, $\tau \to \mu \gamma$. We allow for the presence of a large, model independent, source of lepton flavor violation in the slepton mass matrix in the $\tau -\mu$ sector by the mass insertion approximation and constrain the parameter space using the $\tau$ lepton flavor violating decays together with the $B$-mesons physics observables, the anomalous magnetic moment of the muon, and the dark matter relic density. We further impose the exclusion limit on spin-independent neutralino-nucleon scattering from CDMS and the CDF limits from direct search of the heavy neutral Higgs at the TEVATRON. We find rates probably too small to be observed at future experiments if models have to accommodate for the relic density measured by WMAP and explain the $(g-2{)}_{\mu }$ anomaly: better prospects are found if these two constraints are applied only as upper bounds. The spin-independent neutralino-nucleon cross section in the studied constrained parameter space is just below the present CDMS limit and the running XENON100 experiment will cover the region of the parameter space where the lightest neutralino has large gaugino-Higgsino mixing.

We report a mathematical equivalence between certain models of the Universe relying on domain walls and noncommutative geometries. It is shown that a two-braneworld made of two domain walls can be seen as a “noncommutative” two-sheeted spacetime under certain assumptions. This equivalence also implies a model-independent phenomenology, which is presently studied. Matter swapping between the two branes (or sheets) is predicted through fermionic oscillations induced by magnetic vector potentials. This phenomenon, which might be experimentally studied, could reveal the existence of extra dimensions in a new and accessible way.

The experimental study of $B$ mesons suggest the existence of some new physics contribution to the $B_s^0-{\overline{B}}_s^0$ mixing. We study the implications of a hypothesis that this contribution is generated by the Higgs-induced flavor-changing neutral currents (FCNC). We concentrate on the specific $b\to s$ transition which is described by two complex FCNC parameters, $F_{23}$ and $F_{32}$, and parameters in the Higgs sector. Model-independent constraints on these parameters are derived from the $B_s^0-{\overline{B}}_s^0$ mixing and are used to predict the branching ratios for ${\overline{B}}_s\to {\mu }^{+}{\mu }^{-}$ and ${\overline{B}}_d\to \overline{K}{\mu }^{+}{\mu }^{-}$ numerically by considering general variations in the Higgs parameters assuming that Higgs sector conserves $CP$. Taking the results on $B_s^0-{\overline{B}}_s^0$ mixing derived by the global analysis of UTfit group as a guide we present the general constraints on $F_{23}^{*}{F}_{32}$ in terms of the pseudoscalar mass $M_A$. The former is required to be in the range $\sim (1–5)\times {10}^{-11}{M}_A^2{\mathrm{GeV}}^{-2}$ if the Higgs-induced FCNC represent the dominant source of new physics. The phases of these couplings can account for the large $CP$ violating phase in the $B_s^0-{\overline{B}}_s^0$ mixing except when $F_{23}=F_{32}$. The Higgs contribution to ${\overline{B}}_s\to {\mu }^{+}{\mu }^{-}$ branching ratio can be large, close to the present limit while it remains close to the standard model value in case of the process ${\overline{B}}_d\to \overline{K}{\mu }^{+}{\mu }^{-}$ for all the models under study. We identify and discuss various specific examples which can naturally lead to suppressed FCNC in the $K^0-{\overline{K}}^0$ mixing allowing at the same time the required values for $F_{23}^{*}$ and $F_{32}$.

We consider chiral perturbation theory with a nonzero $\theta$ term. Because of the $CP$ violating term, the vacuum of chiral fields is shifted to a nontrivial element on the $SU(N_f)$ group manifold. The $CP$ violation also provides mixing of different $CP$ eigenstates, between scalar and pseudoscalar, or vector and axialvector, operators. We investigate up to $\mathcal{O}({\theta }^2)$ effects on the mesonic two-point correlators of chiral perturbation theory to the one-loop order. We also address the effects of fixing topology, by using saddle-point integration in the Fourier transform with respect to $\theta$.

Diffractive production of $D^{*}$ mesons at HERA conditions is considered in the framework of a collinear two-gluon exchange model. Theoretical results are compared with recent experimental data.

We study the production of a standard model (SM) Higgs boson in association with a single top quark and either a light jet or $W$ boson at the LHC with a center of mass energy of 14 TeV. Because of the destructive interference of the contributing SM diagrams, the value of the top Yukawa coupling and the sign of the $WWh$ coupling may be probed for Higgs masses above 150 GeV, where $WW$ and $ZZ$ are the dominant Higgs decays. We consider Higgs masses of $m_h=120$, 150, 180, and 200 GeV and devise experimental cuts to extract the signal from SM backgrounds and measure the top Yukawa coupling.