An anthropic understanding of the cosmological constant requires that the vacuum energy at late time scans from one patch of the universe to another. If the vacuum energy during inflation also scans, the various patches of the universe acquire exponentially differing volumes. In a generic landscape with slow-roll inflation, we find that this gives a steeply varying probability distribution for the normalization of the primordial density perturbations, resulting in an exponentially small fraction of observers measuring the Cosmic Background Explorer value of ${10}^{-5}$. Inflationary landscapes should avoid this “$\sigma$ problem,” and we explore features that can allow them to do that. One possibility is that, prior to slow-roll inflation, the probability distribution for vacua is extremely sharply peaked, selecting essentially a single anthropically allowed vacuum. Such a selection could occur in theories of eternal inflation. A second possibility is that the inflationary landscape has a special property: although scanning leads to patches with volumes that differ exponentially, the value of the density perturbation does not vary under this scanning. This second case is preferred over the first, partly because a flat inflaton potential can result from anthropic selection, and partly because the anthropic selection of a small cosmological constant is more successful.

We present a new astrophysical site of the big bang nucleosynthesis (BBN) that are very peculiar compared with the standard BBN. Some models of the baryogenesis suggest that very high baryon density regions were formed in the early universe. On the other hand, recent observations suggest that heavy elements already exist in high red-shifts and the origin of these elements become a big puzzle. Motivated by these, we investigate BBN in very high baryon density regions. BBN proceeds in proton-rich environment, which is known to be like the p-process. However, by taking very heavy nuclei into account, we find that BBN proceeds through both the p-process and the r-process simultaneously. P-nuclei such as ${}^{92}\mathrm{M}\mathrm{o}$, ${}^{94}\mathrm{M}\mathrm{o}$, ${}^{96}\mathrm{R}\mathrm{u}$, ${}^{98}\mathrm{R}\mathrm{u}$ whose origin is not well known are also synthesized.

The possibility of nonnegligible $W$ electric dipole (${\tilde{\mu }}_W$) and magnetic quadrupole (${\tilde{Q}}_W$) moments induced by the most general $HWW$ vertex is examined via the effective Lagrangian technique. It is assumed that new heavy fermions induce an anomalous $CP$-odd component of the $HWW$ vertex, which can be parametrized by an $S{U}_L(2)\times U_Y(1)$-invariant dimension-six operator. This anomalous contribution, when combined with the standard model $CP$-even contribution, leads to $CP$-odd electromagnetic properties of the $W$ boson, which are characterized by the form factors $\Delta \tilde{\kappa }$ and $\Delta \tilde{Q}$. It is found that $\Delta \tilde{\kappa }$ is divergent, whereas $\Delta \tilde{Q}$ is finite, which reflects the fact that the latter cannot be generated at the one-loop level in any renormalizable theory. Assuming reasonable values for the unknown parameters, we found that ${\tilde{\mu }}_W\sim 3-6\times {10}^{-21}e·\mathrm{cm}$, which is 8 orders of magnitude larger than the SM prediction and close to the upper bound derived from the neutron electric dipole moment. The estimated size of the somewhat less-studied ${\tilde{Q}}_W$ moment is of the order of $-{10}^{-36}e·{\mathrm{cm}}^2$, which is 15 orders of magnitude above the SM contribution.

The minimal supersymmetric standard model opens the possibility of electroweak baryogenesis provided that the light scalar top quark (stop) is lighter than the top quark. In addition, the lightest neutralino is an ideal candidate to explain the existence of dark matter. For a light stop with mass close to the lightest neutralino, the stop-neutralino coannihilation mechanism becomes efficient, thus rendering the predicted dark matter density compatible with observations. Such a stop may however remain elusive at hadron colliders. Here it is shown that a future linear collider provides a unique opportunity to detect and study the light stop. The production of stops with small stop-neutralino mass differences is studied in a detailed experimental analysis with a realistic detector simulation including a CCD vertex detector for flavor tagging. Furthermore, the linear collider, by precision measurements of superpartner masses and mixing angles, also allows to determine the dark matter relic density with an accuracy comparable to recent astrophysical observations.

If new physics (NP) is present in $B\to \pi \pi$ decays, it can affect the isospin $I=2$ or $I=0$ channels. In this paper, we discuss various methods for detecting and measuring this NP. The techniques have increasing amounts of theoretical hadronic input. If NP is eventually detected in $B\to \pi \pi$—there is no evidence for it at present—one will be able to distinguish $I=2$ and $I=0$, and measure its parameters, using these methods.

Experimental results for the radiative energy loss of 178 GeV positrons in Cu, Au, and W targets are presented. It is shown that for a few micron thick target, effects related to the formation zone disappear, in particular, the suppression due to the Landau-Pomeranchuk-Migdal and Ternovskii-Shul’ga-Fomin mechanisms. This disappearance may restrict the region of applicability of thin foils as a target for energy-selective production of high energy photons. Furthermore, transition radiation dominated by multiple scattering and structured target interference effects are shown to be likely ingredients for an accurate description of the data obtained at low photon energies.

A new method is proposed to quantize open strings in this paper. To illustrate our method, we analyze free open string as well as open string in the D-brane background with a nonvanishing B-field, respectively. The Poisson brackets among Fourier components are obtained firstly then we get the Poisson brackets among open string’s coordinates. The noncommutativity of coordinates along the D-brane is reproduced. Some ambiguities in the previous discussions can be avoided.

We use on-shell recursion relations to determine the one-loop QCD scattering amplitudes with a massless external quark pair and an arbitrary number ($n-2$) of positive-helicity gluons. These amplitudes are the last of the unknown infrared- and ultraviolet-finite loop amplitudes of QCD. The recursion relations are similar to ones applied at tree level, but contain new nontrivial features corresponding to poles present for complex momentum arguments but absent for real momenta. We present the relations and the compact solutions to them, valid for all $n$. We also present compact forms for the previously computed one-loop $n$-gluon amplitudes with a single negative helicity and the rest positive helicity.

We study the Hamilton-Jacobi and massive Klein-Gordon equations in the general Kerr-(Anti) de Sitter black hole background in all dimensions. Complete separation of both equations is carried out in cases when there are two sets of equal black hole rotation parameters. We analyze explicitly the symmetry properties of these backgrounds that allow for this Liouville integrability and construct a nontrivial irreducible Killing tensor associated with the enlarged symmetry group which permits separation. We also derive first-order equations of motion for particles in these backgrounds and examine some of their properties. This work greatly generalizes previously known results for both the Myers-Perry metrics, and the Kerr-(Anti) de Sitter metrics in higher dimensions.

The unique, conical space-time created by cosmic strings brings about distinctive gravitational lensing phenomena. The variety of these distinctive phenomena is increased when the strings have nontrivial mutual interactions. In particular, when strings bind and create junctions, rather than intercommute, the resulting configurations can lead to novel gravitational lensing patterns. In this brief note, we use exact solutions to characterize these phenomena, the detection of which would be strong evidence for the existence of complex cosmic string networks of the kind predicted by string theory-motivated cosmic string models. We also correct some common errors in the lensing phenomenology of straight cosmic strings.

We consider an inflating brane world setup in which 4-dimensional Lorentz invariance is violated at high 3-momentum scale $P_{LV}\gg H$, where $H$ is the inflationary Hubble parameter. We study massless scalar field in this background as a model for cosmological perturbations. Towards the end of inflation, the spectrum has both the standard, 4-dimensional part due to a brane-localized mode, and exotic, bulk-induced contribution. The suppression of the latter is power-law only, $(H/P_{LV}{)}^{\alpha }$, provided that there exists bulk modes with energies $\omega \ll H$. Contrary to general expectations, the exponent $\alpha$ may be smaller than 2, and even smaller than 1, depending on details of the bulk geometry. Furthermore, the overall amplitude of the bulk-induced perturbations is enhanced as compared to the standard part, so the effects due to Lorentz violation may dominate over the standard mechanism even for $P_{LV}\gg H$.

In real-time, thermal field theory there are $2^n$ different $n$-point functions, but there are two linear combinations that sum to zero. Simple proofs of the two sum rules are given. Each sum rule has two forms: one for the one-particle-reducible functions and one for the amputated functions.

Recent $CP$ violation results in $B$ decays suggest that $Z$ penguins may have large weak phase. This can be realized by the four generation (standard) model. Concurrently, $B\to X_s{\ell }^{+}{\ell }^{-}$ and $B_s$ mixing allow for sizable $V_{t^{\prime }s}^{*}{V}_{t^{\prime }b}$ only if it is nearly imaginary. Such large effects in $b\leftrightarrow s$ transitions would affect $s\leftrightarrow d$ transitions, as kaon constraints would demand $V_{t^{\prime }d}\ne 0$. Using $\Gamma (Z\to b\overline{b})$ to bound $|V_{t^{\prime }b}|$, we infer sizable $|V_{t^{\prime }s}|\lesssim |V_{t^{\prime }b}|\lesssim |V_{us}|$. Imposing ${\epsilon }_K$, $K^{+}\to {\pi }^{+}\nu \overline{\nu }$ and ${\epsilon }^{\prime }/\epsilon$ constraints, we find $V_{t^{\prime }d}^{*}{V}_{t^{\prime }s}\sim$ few $\times {10}^{-4}$ with large phase, enhancing $K_L\to {\pi }^0\nu \overline{\nu }$ to $5\times {10}^{-10}$ or even higher. Interestingly, $\Delta m_{B_d}$ and $\sin 2{\Phi }_{B_d}$ are not much affected, as $|V_{t^{\prime }d}^{*}{V}_{t^{\prime }b}|\ll |V_{td}^{*}{V}_{tb}|\sim 0.01$.

We present the cross sections for the hadroproduction of gluinos by taking into account the $CP$ odd dipole operators in supersymmetric QCD. The dependence of the cross sections on these operators is analyzed for the hadron colliders the Tevatron ($\sqrt{S}=1.8\mathrm{TeV}$) and the CERN LHC ($\sqrt{S}=14\mathrm{TeV}$). The enhancement of the hadronic cross section is obviously mass dependent and for a 500 GeV gluino is up to 16% (over 73 pb) at the LHC while it is 8% (over 0.63 fb) at the Tevatron.

It has been suggested that two different excesses of events observed at CERN LEP could be interpreted as the CP-even Higgs bosons of the minimal supersymmetric standard model (MSSM) with masses of approximately 98 and 114 GeV. If this is the case, the entire MSSM-Higgs sector is required to be light. In this article, we explore such a scenario in detail. We constrain the Higgs and supersymmetric spectrum using $B$ physics constraints as well as the magnetic moment of the muon. We then point out the implications for neutralino dark matter—next generation direct detection experiments will be sensitive to all MSSM models with such a Higgs sector. Finally, we find that all models outside a very narrow corridor of parameter space have a charged Higgs boson which will be observed at the CERN LHC. In those exceptional models which do not contain an observable charged Higgs, a light top squark will always be seen at the LHC, and likely at the Tevatron.

We present an unquenched lattice calculation for the SU(3) flavor breaking ratios of the heavy-light decay constants and the $\Delta B=2$ matrix elements. The calculation was performed on ${16}^3\times 32$ lattices with two dynamical flavors of domain-wall quarks and inverse lattice spacing $1/a=1.69(5)\mathrm{GeV}$. Heavy quarks were implemented using an improved lattice formulation of the static approximation. In the infinite heavy-quark mass limit we obtain $f_{B_s}/f_{B_d}=1.29(4)(6)$, $B_{B_s}/B_{B_d}=1.06(6)(4)$, $\xi =1.33(8)(8)$ where the first error is statistical and the second systematic.

The extension of the method [A. Manashov, M. Kirch, and A. Schäfer, Phys. Rev. Lett. 95, 012002 (2005).] for solving the leading order evolution equation for generalized parton distributions (GPDs) is presented. We obtain the solution of the evolution equation both for the flavor nonsinglet quark GPD and singlet quark and gluon GPDs. The properties of the solution and, in particular, the asymptotic form of GPDs in the small $x$ and $\xi$ region are discussed.

We calculate the important next-to-leading-order contributions to the $B\to \pi K$, $\pi \pi$ decays from the vertex corrections, the quark loops, and the magnetic penguins in the perturbative QCD approach. It is found that the latter two reduce the leading-order penguin amplitudes by about 10% and modify only the $B\to \pi K$ branching ratios. The main effect of the vertex corrections is to increase the small color-suppressed tree amplitude by a factor of 3, which then resolves the large difference between the direct $CP$ asymmetries of the $B^0\to {\pi }^{\mp }{K}^{\pm }$ and $B^{\pm }\to {\pi }^0{K}^{\pm }$ modes. The puzzle from the large $B^0\to {\pi }^0{\pi }^0$ branching ratio still remains.

A new method to study the retardation effects in mesons is presented. Inspired from the covariant oscillator quark model, it is applied to the rotating string model in which a nonzero value is allowed for the relative time between the quark and the antiquark. The straight line ansatz is used to describe the string, and the relevance of this approximation is tested. This approach leads to a retardation term which behaves as a perturbation of the meson mass operator. It is shown that this term preserves the Regge trajectories for light mesons. As an illustration, we show that a satisfactory agreement with the experimental data can be obtained if the quark self-energy contribution is added. The consequences of the retardation on the Coulomb interaction and the wave function are also analyzed.