We consider non-Abelian Bogomol’nyi-Prasad-Sommerfield-saturated flux tubes (strings) in $\mathcal{N}=2$ supersymmetric QCD deformed by superpotential terms of a special type breaking $\mathcal{N}=2$ supersymmetry down to $\mathcal{N}=1$. Previously it was believed that world sheet supersymmetry is accidentally enhanced due to the facts that $\mathcal{N}=(1,1)$ supersymmetry is automatically elevated up to $\mathcal{N}=(2,2)$ on $CP(N-1)$ and, at the same time, there are no $\mathcal{N}=(0,2)$ generalizations of the bosonic $CP(N-1)$ model. Edalati and Tong noted that the target space is in fact $CP(N-1)\times C$ rather than $CP(N-1)$. This allowed them to suggest a heterotic $\mathcal{N}=(0,2)$ sigma model, with the $CP(N-1)$ target space for bosonic fields and an extra right-handed fermion which couples to the fermion fields of the $\mathcal{N}=(2,2)$ $CP(N-1)$ model. We derive the heterotic $\mathcal{N}=(0,2)$ world sheet model directly from the bulk theory. The relation between the bulk and world sheet deformation parameters we obtain does not coincide with that suggested by Edalati and Tong at large values of the deformation parameter. For polynomial deformation superpotentials in the bulk we find nonpolynomial response in the world sheet model. We find a geometric representation for the heterotic model. Supersymmetry is proven to be spontaneously broken for small deformations (at the quantum level). This confirms Tong’s conjecture. A proof valid for large deformations will be presented in the subsequent publication.

It has been suggested that after brane-antibrane inflation in a Klebanov-Strassler (KS) warped throat, metastable Kaluza-Klein excitations can be formed due to nearly-conserved angular momenta along isometric directions in the throat. If sufficiently long lived, these relics could conflict with big bang nucleosynthesis or baryogenesis by dominating the energy density of the Universe. We make a detailed estimate of the decay rate of such relics using the low-energy effective action of type IIB string theory compactified on the throat geometry, with attention to powers of the warp factor. We find that it is necessary to turn on supersymmetry (SUSY)-breaking deformations of the KS background in order to ensure that the most dangerous relics will decay fast enough. The decay rate is found to be much larger than the naive guess based on the dimension of the operators which break the angular isometries of the throat. For an inflationary warp factor of order $w\sim {10}^{-4}$, we obtain the bound $M_{3/2}\gtrsim {10}^9\mathrm{GeV}$ on the scale of SUSY breaking to avoid cosmological problems from the relics, which is satisfied in the Kachru, Kallosh, Linde, and Trivedi construction assumed to stabilize the compactification. Given the requirement that the relics decay before nucleosynthesis or baryogenesis, we place bounds on the mass of the relic as a function of the warp factor in the throat for more general warped backgrounds.

The bispectrum of cosmic microwave background (CMB) anisotropies is a well-known probe of the non-Gaussianity of primordial perturbations. Just as the intervening large-scale structure modifies the CMB angular power spectrum through weak gravitational lensing, the CMB primary bispectrum generated at the last scattering surface is also modified by lensing. We discuss the lensing modification to the CMB bispectrum and show that lensing leads to an overall decrease in the amplitude of the primary bispectrum at multipoles of interest between 100 and 2000 through additional smoothing introduced by lensing. Since weak lensing is not accounted for in current estimators of the primordial non-Gaussianity parameter, the existing measurements of $f_{\mathrm{NL}}$ of the local model with WMAP out to $l_{\max }\sim 750$ is biased low by about 6%. For a high resolution experiment such as Planck, the lensing modification to the bispectrum must be properly included when attempting to estimate the primordial non-Gaussianity or the bias will be at the level of 30%. For Planck, weak lensing increases the minimum detectable value for the non-Gaussianity parameter of the local type $f_{\mathrm{NL}}$ to 7 from the previous estimate of about 5 without lensing. The minimum detectable value of $f_{\mathrm{NL}}$ for a cosmic variance limited experiment is also increased from less than 3 to $\sim 5$.

While observations indicate that the predominant source of cosmic inhomogeneities are adiabatic perturbations, there are a variety of candidates to provide auxiliary trace effects, including inflation-generated primordial tensors and cosmic defects which both produce B-mode cosmic microwave background polarization. We investigate whether future experiments may suffer confusion as to the true origin of such effects, focusing on the ability of Planck to distinguish tensors from cosmic strings, and show that there is no significant degeneracy.

We construct LHC signature footprints for four semirealistic string/M theory vacua with a minimal supersymmetric standard model visible sector. We find that they all give rise to limited regions in LHC signature space and are qualitatively different from each other for understandable reasons. We also propose a technique in which correlations of LHC signatures can be effectively used to distinguish among these string theory vacua. We expect the technique to be useful for more general string vacua. We argue that further systematic analysis with this approach will allow LHC data to disfavor or exclude major “corners” of string/M theory and favor others. The technique can be used with limited integrated luminosity and improved.

Dynamical symmetry breaking and meson masses are studied in the Nambu–Jona-Lasinio model at finite temperature and chemical potential using dimensional regularization. Since the model is not renormalizable in four space-time dimensions, physical results and parameters depend on the regularization method. Following the imaginary-time formalism, we introduce the temperature $T$ and the chemical potential $\mu$. The parameters of the model are fixed by calculating the pion mass and decay constant in dimensional regularization at $T=\mu =0$.

We discuss the average collisional energy loss $dE/dx$ of a heavy quark crossing a quark-gluon plasma, in the limit of high quark energy $E\gg M^2/T$, where $M$ is the quark mass and $T\ll M$ is the plasma temperature. In the fixed coupling approximation, at leading order $dE/dx\propto {\alpha }_s^2$, with a coefficient which is logarithmically enhanced. The soft logarithm arising from $t$-channel scattering off thermal partons is well known, but a collinear logarithm from $u$-channel exchange had previously been overlooked. We also determine the constant beyond those leading logarithms. We then generalize our calculation of $dE/dx$ to running coupling. We estimate the remaining theoretical uncertainty of $dE/dx$, which turns out to be quite large under Relativistic Heavy Ion Collider conditions. Finally, we point out an approximate relation between $dE/dx$ and the QCD Debye mass, from which we derive an upper bound to $dE/dx$ for all quark energies.

The Taylor coefficients of flavor diagonal and off-diagonal susceptibilities as well as baryon number, isovector, and electric charge susceptibilities are considered within a phenomenological quasiparticle model of the quark-gluon plasma and successfully compared with available lattice QCD data up to fourth-order for two degenerate quark flavors. These susceptibility coefficients represent sensible probes of baryon-density effects in the equation of state. The baryon charge is carried, in our model, by quark-quasiparticle excitations for hard momenta.

In the so-called two Higgs doublet model for the top quark (T2HDM), first suggested by Das and Kao, the top quark receives a special status, which endows it with a naturally large mass, and also potentially gives rise to large flavor changing neutral currents only in the up-quark sector. In this paper, we calculate the branching ratio for the rare decays $t\to ch$ and $h\to \overline{t}c$ ($h$ is a neutral Higgs scalar) in the T2HDM, at tree level and at 1-loop when it exceeds the tree level. We compare our results to predictions from other versions of 2HDM’s and find that the scalar flavor changing neutral currents in the T2HDM can play a significant role in these decays. In particular, the 1-loop mediated decays can be significantly enhanced in the T2HDM compared with the 2HDM of types  I and II, in some instances reaching $\mathrm{BR}\sim {10}^{-4}$, which is within the detectable level at the LHC.

I consider the thermodynamics of the BTZ black hole in the presence of the higher curvature and gravitational Chern-Simons terms, and its statistical entropy. I propose a new thermodynamical entropy, which is manifestly non-negative, such that the second law of thermodynamics is satisfied. I show that the new thermodynamical entropy agrees perfectly with the statistical entropy for all the values of the conformal factor of the higher curvature terms and the coupling constant of the gravitational Chern-Simons term, in contrast to some disagreements in the literature. The agreement with both the higher curvature and gravitational Chern-Simons terms is possible because of an appropriate balancing of them, though it is not a trivial matter because of a conflict in the appropriate Hilbert space for a well-defined conformal field theory for each term.

We study quintessence-driven, spatially flat, expanding Friedmann-Robertson-Walker cosmologies that arise naturally from string theory formulated in a supercritical number of spacetime dimensions. The tree-level potential of the string theory produces an equation of state at the threshold between accelerating and decelerating cosmologies, and the resulting spacetime is globally conformally equivalent to Minkowski space. We demonstrate that exact solutions exist with a condensate of the closed-string tachyon, the simplest of which is a Liouville wall moving at the speed of light. We rely on the existence of this solution to derive constraints on the couplings of the tachyon to the dilaton and metric in the string theory effective action. In particular, we show that the tachyon dependence of the Einstein term must be nontrivial.

We examine whether renormalization effects can cause Newton’s constant to change dramatically with energy, perhaps even reducing the scale of quantum gravity to the TeV region without the introduction of extra dimensions. We examine a model that realizes this possibility and describe experimental signatures from the production of small black holes.

We show how one can systematically construct vacuum solutions to Einstein field equations with $D-2$ commuting Killing vectors in $D>4$ dimensions. The construction uses Einstein-scalar field seed solutions in four dimensions and is performed both for the case when all the Killing directions are spacelike, as well as when one of the Killing vectors is timelike. The later case corresponds to generalizations of stationary axially symmetric solutions to higher dimensions. Some examples representing generalizations of known higher dimensional stationary solutions are discussed in terms of their rod structure and horizon locations and deformations.

We investigate post-Newtonian parameters in the tensor-vector-scalar theory in a general setting while previous research has been restricted to spherically symmetric cases. Based on the assumption that both the physical and Einstein metrics have a Minkowski metric at the zeroth order, we show $\gamma =1$ as in the previous research. We find two remarkable things for other parameters. The first is the value $\beta =1$, while it has been reported that $\beta \ne 1$ for the case when the vector field is not purely timelike. This discrepancy occurs from the above assumption which is natural as a starting point. The second is the result that the Newtonian potential must be static to be consistent with the vector equation. As a result, we cannot determine ${\alpha }_1$ and ${\alpha }_2$. We consider that it is related to the instability against linear perturbation and occurrence of caustic singularities for various initial perturbations which have been reported recently.

A description of the transition from the inflationary epoch to radiation domination requires the understanding of quantum fields out of thermal equilibrium, particle creation and thermalization. This can be studied from first principles by solving a set of truncated real-time Schwinger-Dyson equations, written in terms of the mean field (inflaton) and the field propagators, derived from the two-particle irreducible effective action. We investigate some aspects of this problem by considering the dynamics of a slow-rolling mean field coupled to a second quantum field, using a ${\phi }^2{\chi }^2$ interaction. We focus on thermal effects. It is found that interactions lead to an earlier end of slow roll and that the evolution afterwards depends on details of the heatbath.

We calculate the effect that a primordial homogeneous magnetic field, ${\mathcal{B}}_0$, will have on the different CMB power spectra due to Faraday rotation. Concentrating on the $TB$, $EB$, and $BB$ correlations, we forecast the ability for future CMB polarization experiments to constrain ${\mathcal{B}}_0$. Our results depend on how well the foregrounds can be subtracted from the CMB maps, but we find a predicted error between ${\sigma }_{{\mathcal{B}}_0}=4\times {10}^{-11}\mathrm{G}$ (for the QUIET experiment with foregrounds perfectly subtracted) and $3\times {10}^{-10}\mathrm{G}$ (with the Clover experiment with no foreground subtraction). These constraints are two orders of magnitude better than the present limits on ${\mathcal{B}}_0$.

We discuss the impact of charged massive particle big bang nucleosynthesis to explore the nature of the reheating of the Universe in the case that a new extremely long-lived charged massive particle (CHAMP) exists. If the mass of the CHAMP is within collider reach and its lifetime is longer than ${10}^4\mathrm{s}$, the comparison between the charged big bang nucleosynthesis prediction and observed ${}^6\mathrm{Li}$ abundances may indicate nonstandard reheating in the early Universe without relying on details of the decay properties. Even if the CHAMP mass is outside the reach of colliders, the cosmological considerations may provide a nontrivial hint for the existence of such very heavy long-lived CHAMPs from the late Universe if the daughter particles are the dominant component of the present dark matter. We consider a low reheating temperature model as an example of the nonstandard reheating scenarios.

The lightest neutralino, as the dark matter candidate, can be gravitationally captured by the Sun. In this paper, we studied the high energy neutrino signals from solar neutralino annihilations in the core of the Sun in the anomaly mediated supersymmetry breaking (AMSB) model. Based on the event-by-event Monte Carlo simulation code WimpSim, we studied the detailed energy and angular spectrum of the final muons at large neutrino telescope IceCube. More precisely, we simulated the processes since the production of neutrino via neutralino annihilation in the core of the Sun, neutrino propagation from the Sun to the Earth, as well as the converting processes from neutrino to muon. Our results showed that in the AMSB model it is possible to observe the energetic muons at IceCube, provided that the lightest neutralino has a relatively large Higgsino component, as a rule of thumb $N_{13}^2+N_{14}^2>4\%$, or equivalently, ${\sigma }_{\mathrm{SD}}>{10}^{-5}\mathrm{pb}$. Especially, for our favorable parameters the signal annual events can reach 102, and the statistical significance can reach more than 20. We pointed out that the energy spectrum of muons may be used to distinguish among the AMSB model and other supersymmetry breaking scenarios.

We study double Higgs production at the future linear collider in the framework of the two Higgs doublet models through the following channels: $e^{+}{e}^{-}\to {\Phi }_i{\Phi }_{j}Z$, ${\Phi }_i=h^0$, $H^0$, $A^0$, $H^{\pm }$. All these processes are sensitive to triple Higgs couplings. Hence observations of them provide information on the triple Higgs couplings that help reconstructing the scalar potential. We also discuss the double Higgs-Strahlung $e^{+}{e}^{-}\to h^0{h}^{0}Z$ in the decoupling limit where $h^0$ mimics the standard model Higgs boson. The processes $e^{+}{e}^{-}\to h^0{h}^{0}Z$ and $e^{+}{e}^{-}\to h^0{H}^{0}Z$ are also discussed in the fermiophobic limit where distinctive signatures such as $4\gamma +X$, $2\gamma +X$, and $6\gamma +X$ are expected in the Type-I two Higgs doublet model.