We discuss cosmological consequences of the existence of physics beyond the standard model that exhibits Banks-Zaks and unparticle behavior in the UV and IR, respectively. We first derive the equation of state for unparticles and use it to obtain the temperature dependence of the corresponding energy and entropy densities. We then formulate the Boltzmann and Kubo equations for both the unparticles and the Banks-Zaks particles, and use these results to determine the equilibrium conditions between the standard model and the new physics. We conclude by obtaining the constraints on the effective number of degrees of freedom of unparticles imposed by big-bang nucleosynthesis.

We describe a novel use of the Dalitz plot to probe $CP$ symmetry in three-body modes of $B$ and $D$ mesons. It is based on an observable inspired by astronomers’ practice, namely the significance in the difference between corresponding Dalitz plot bins. It provides a model-independent mapping of local $CP$ asymmetries. We illustrate the method for probing $CP$ symmetry in the two complementary cases of $B$ and $D$ decays: in the former sizable or even large effects can be expected, yet have to be differentiated against leading standard model contributions, while in the latter one cannot count on sizable effects, yet has to deal with much less standard model background.

Using the unitarity, $SU(2)$ and $C$ invariance of hadronic interactions, the bounds on final state phases are derived. It is shown that values obtained for the final state phases relevant for the direct $CP$ asymmetries $A_{CP}(B^0\to K^{+}{\pi }^{-},K^0{\pi }^0)$ are compatible with experimental values for these asymmetries. For the decays $B^0\to D^{(*)-}{\pi }^{+}(D^{(*)+}{\pi }^{-})$ described by two independent single amplitudes $A_f$ and $A_{\overline{f}}^{\prime }$ with different weak phases (0 and $\gamma$) it is argued that the $C$ invariance of hadronic interactions implies the equality of the final state phase ${\delta }_f$ and ${\delta }_{\overline{f}}^{\prime }$. This in turn implies that the $CP$ asymmetry $\frac{S_{+}+S_{-}}{2}$ is determined by weak phase ($2\beta +\gamma$) only, whereas $\frac{S_{+}-S_{-}}{2}=0$. Assuming factorization for tree graphs, it is shown that the $B\to D^{(*)}$ form factors are in excellent agreement with the heavy quark effective theory. From the experimental value for $(\frac{S_{+}+S_{-}}{2}{)}_{D^{*}\pi }$, the bound $\sin (2\beta +\gamma )\ge 0.69$ is obtained and $(\frac{S_{+}+S_{-}}{2}{)}_{D_S^{*-}{K}^{+}}\approx -(0.41\pm 0.08)\sin \gamma$ is predicted. For the decays described by the amplitudes $A_f\ne A_{\overline{f}}$ such as $B^0\to {\rho }^{+}{\pi }^{-}$: $A_{\overline{f}}$ and $B^0\to {\rho }^{-}{\pi }^{+}$: $A_f$ where these amplitudes are given by tree and penguin diagrams with different weak phases, it is shown that in the limit ${\delta }_{f,\overline{f}}^T\to 0$, $r_{f,\overline{f}}\cos {\delta }_{f,\overline{f}}=\cos \alpha$ and $\frac{S_{\overline{f}}}{S_f}=\frac{S+\Delta S}{S-\Delta S}=-\frac{\sqrt{1-C_{\overline{f}}^2}}{\sqrt{1-C_f^2}}$.

The baryon magnetic and transition magnetic moments are computed in heavy baryon chiral perturbation theory in the large-$N_c$ limit, where $N_c$ is the number of colors. One-loop nonanalytic corrections of orders $m_q^{1/2}$ and $m_q\ln m_q$ are incorporated into the analysis, where contributions of both intermediate octet and decuplet baryon states are explicitly included. Expressions are obtained in the limit of vanishing baryon mass differences and compared with the current experimental data. Furthermore, a comparison with conventional heavy baryon chiral perturbation theory is carried out for three light quarks flavors and at the physical value $N_c=3$.

We study a specific texture of the neutrino mass matrix, namely the models with one $2\times 2$ subdeterminant equal to zero. We carry out a complete phenomenological analysis with all possible relevant correlations. Every pattern of the six possible ones is found able to accommodate the experimental data, with three cases allowing also for noninvertible mass matrices. We present symmetry realizations for all the models.

We present measurements of the branching fraction $\mathcal{B}$ and longitudinal polarization fraction $f_L$ for $B^0\to a_1(1260{)}^{+}{a}_1(1260{)}^{-}$ decays, with $a_1(1260{)}^{\pm }\to {\pi }^{-}{\pi }^{+}{\pi }^{\pm }$. The data sample, collected with the BABAR detector at the SLAC National Accelerator Laboratory, represents $465\times {10}^6$ produced $B\overline{B}$ pairs. We measure $\mathcal{B}(B^0\to a_1(1260{)}^{+}{a}_1(1260{)}^{-})\times [\mathcal{B}(a_1(1260{)}^{+}\to {\pi }^{-}{\pi }^{+}{\pi }^{+}){]}^2=(11.8\pm 2.6\pm 1.6)\times {10}^{-6}$ and $f_L=0.31\pm 0.22\pm 0.10$, where the first uncertainty is statistical and the second systematic. The decay mode is measured with a significance of 5.0 standard deviations including systematic uncertainties.

We present measurements of the top quark mass ($m_t$) in $t\overline{t}$ candidate events with two final state leptons using $1{\mathrm{fb}}^{-1}$ of data collected by the D0 experiment. Our data sample is selected by requiring two fully identified leptons or by relaxing one lepton requirement to an isolated track if at least one jet is tagged as a $b$ jet. The top quark mass is extracted after reconstructing the event kinematics under the $t\overline{t}$ hypothesis using two methods. In the first method, we integrate over expected neutrino rapidity distributions, and in the second we calculate a weight for the possible top quark masses based on the observed particle momenta and the known parton distribution functions. We analyze 83 candidate events in the data and obtain $m_t=176.2\pm 4.8(\mathrm{stat})\pm 2.1(\mathrm{sys})\mathrm{GeV}$ and $m_t=173.2\pm 4.9(\mathrm{stat})\pm 2.0(\mathrm{sys})\mathrm{GeV}$ for the two methods, respectively. Accounting for correlations between the two methods, we combine the measurements to obtain $m_t=174.7\pm 4.4(\mathrm{stat})\pm 2.0(\mathrm{sys})\mathrm{GeV}$.

We present the result from a precision measurement of the mass of the $\tau$ lepton, $M_{\tau }$, based on $423{\mathrm{fb}}^{-1}$ of data recorded at the ${\rm Y}(4S)$ resonance with the BABAR detector. Using a pseudomass endpoint method, we determine the mass to be $1776.68\pm 0.12(\mathrm{stat})\pm 0.41(\mathrm{syst})\mathrm{MeV}$. We also measure the mass difference between the ${\tau }^{+}$ and ${\tau }^{-}$, and obtain $(M_{{\tau }^{+}}-M_{{\tau }^{-}})/M_{\mathrm{AVG}}^{\tau }=(-3.4\pm 1.3(\mathrm{stat})\pm 0.3(\mathrm{syst}))\times {10}^{-4}$, where $M_{\mathrm{AVG}}^{\tau }$ is the average value of $M_{{\tau }^{+}}$ and $M_{{\tau }^{-}}$.

One of the most active field of research in general relativity is the description of the spin properties of astrophysical objects. The main tool in the description of the gravitational waves emitted by compact binary systems in the inspiral era is the post-Newtonian (PN) approximation, where spin effects, namely, spin-orbit and spin-spin interactions, become important in higher orders. These interactions are described with coupled differential equations in general, but the PN approximation scheme gives the opportunity to solve them order by order. In the present work the effects of the spin-orbit and spin-spin interactions are described in the spin-precession equations with the use of the PN approximation up to 1.5 PN order. The decoupled angular equations describing the evolution of the direction of the spin vectors are given, and they are solved both in the eccentric and circular orbit cases. Since the spin-precession equations do not have a Newtonian contribution it is nontrivial to determine the relative order of the different variables. This analysis is also included up to the order of the spin-spin interaction.

We study the impact of a strongly first-order electroweak phase transition on the thermal relic abundance of particle species that could constitute the dark matter and that decoupled before the phase transition occurred. We define a dilution factor induced by generic first-order phase transitions, and we explore the parameter space of the minimal supersymmetric extension to the standard model to determine which phase transition temperatures and dilution factors are relevant for the lightest neutralino as a dark matter candidate. We then focus on a specific toy-model setup that could give rise to a strongly first-order electroweak phase transition, and proceed to a detailed calculation of dilution factors and transition temperatures, comparing our findings to actual neutralino dark matter models. Typical models that would produce an excessive thermal relic density and that can be salvaged postulating a strongly first-order electroweak phase transition include massive (multi-TeV) wino or Higgsino-like neutralinos, as well as binolike neutralinos in a wider mass range, with masses as low as 400 GeV. If LHC data indicate an inferred thermal neutralino relic abundance larger than the cold dark matter density, the mismatch could thus potentially be explained by electroweak-scale physics that will also be thoroughly explored with collider experiments in the near future.

Weak gravitational lensing leaves a characteristic imprint on the cosmic microwave background temperature and polarization angular power spectra. Here, we investigate the possible constraints on the integrated lensing potential from future cosmic microwave background angular spectra measurements expected from Planck and EPIC. We find that Planck and EPIC will constrain the amplitude of the integrated projected potential responsible for lensing at 6% and 1% level, respectively, with very little sensitivity to the shape of the lensing potential. We discuss the implications of such a measurement in constraining dark energy and modified gravity scalar-tensor theories. We then discuss the impact of a wrong assumption on the weak lensing potential amplitude on cosmological parameter inference.

Group theoretical arguments seem to indicate the discrete symmetry $S_4$ as the minimal flavor symmetry compatible with tribimaximal neutrino mixing. We prove in a model-independent way that indeed $S_4$ can realize exact tribimaximal mixing through different symmetry breaking patterns. We present two models in which lepton tribimaximal mixing is realized in different ways and for each one we discuss the superpotential that leads to the correct breaking of the flavor symmetry.

Previous work on electroweak radiative corrections to high-energy scattering using soft-collinear effective theory (SCET) has been extended to include external transverse and longitudinal gauge bosons and Higgs bosons. This allows one to compute radiative corrections to all parton-level hard scattering amplitudes in the standard model to next-to-leading-log order, including QCD and electroweak radiative corrections, mass effects, and Higgs exchange corrections, if the high-scale matching, which is suppressed by two orders in the log counting, and contains no large logs, is known. The factorization structure of the effective theory places strong constraints on the form of gauge theory amplitudes at high energy for massless and massive gauge theories, which are discussed in detail in the paper. The radiative corrections can be written as the sum of process-independent one-particle collinear functions, and a universal soft function. We give plots for the radiative corrections to $q\overline{q}\to W_T{W}_T$, $Z_T{Z}_T$, $W_L{W}_L$, and $Z_{L}H$, and $gg\to W_T{W}_T$ to illustrate our results. The purely electroweak corrections are large, ranging from 12% at 500 GeV to 37% at 2 TeV for transverse $W$ pair production, and increasing rapidly with energy. The estimated theoretical uncertainty to the partonic (hard) cross section in most cases is below 1%, smaller than uncertainties in the parton distribution functions. We discuss the relation between SCET and other factorization methods, and derive the Magnea-Sterman equations for the Sudakov form factor using SCET, for massless and massive gauge theories, and for light and heavy external particles.

In multi-Higgs-doublet models the alignment in flavor space of the relevant Yukawa matrices guarantees the absence of tree-level flavor-changing couplings of the neutral scalar fields. We analyze the consequences of this condition within the two-Higgs-doublet model and show that it leads to a generic Yukawa structure which contains as particular cases all known specific implementations of the model based on ${\mathcal{Z}}_2$ symmetries. All possible freedom in the Yukawa sector gets parametrized in terms of three complex couplings ${\varsigma }_f$. In spite of having flavor conservation in the neutral scalar couplings, the phases of these three parameters represent potential new sources of $CP$ violation.

In this article we quantize (massive) higher spin ($1\le j\le 2$) fields by means of Dirac’s constrained Hamilton procedure both in the situation were they are totally free and were they are coupled to (an) auxiliary field(s). A full constraint analysis and quantization is presented by determining and discussing all constraints and Lagrange multipliers and by giving all equal times (anti)commutation relations. Also we construct the relevant propagators. In the free case we obtain the well-known propagators and show that they are not covariant, which is also well known. In the coupled case we do obtain covariant propagators (in the spin-$3/2$ case this requires $b=0$) and show that they have a smooth massless limit connecting perfectly to the massless case (with auxiliary fields). We notice that in our system of the spin-$3/2$ and spin-2 case the massive propagators coupled to conserved currents only have a smooth limit to the pure massless spin-propagator, when there are ghosts in the massive case.

We use the semiclassical approximation in perturbative scalar quantum electrodynamics to calculate the quantum correction to the Larmor radiation formula to first order in Planck’s constant in the nonrelativistic approximation, choosing the initial state of the charged particle to be a momentum eigenstate. We calculate this correction in two cases: in the first case the charged particle is accelerated by a time-dependent but space-independent vector potential whereas in the second case it is accelerated by a time-independent vector potential which is a function of one spatial coordinate. We find that the corrections in these two cases are different even for a charged particle with the same classical motion. The correction in each case turns out to be nonlocal in time in contrast to the classical approximation.

We show that a Nambu-Jona-Lasinio type four-fermion coupling at the $z=3$ Lifshitz-like fixed point in $3+1$ dimensions is asymptotically free and generates a mass scale dynamically. This result is nonperturbative in the limit of a large number of fermion species. The theory is ultraviolet complete and at low energies exhibits Lorentz invariance as an emergent spacetime symmetry. Many of our results generalize to $z=d$ in odd $d$ spatial dimensions; $z=d=1$ corresponds to the Gross-Neveu model. The above mechanism of mass generation has potential applications to the fermion mass problem and to dynamical electroweak symmetry breaking. We present a scenario in which a composite Higgs field arises from a condensate of these fermions, which then couples to quarks and leptons of the standard model. Such a scenario could eliminate the need for the Higgs potential and the associated hierarchy problem. We also show that the axial anomaly formula at $z=3$ coincides with the usual one in the relativistic domain.

The absorption cross section of Reissner-Nordström black holes for the electromagnetic field is computed numerically for arbitrary frequencies, taking into account the coupling of the electromagnetic and gravitational perturbations. We also compute the conversion coefficients of electromagnetic to gravitational waves by scattering from a Reissner-Nordström black hole.

Using a Legendre transformation, we compute the unconstrained Hamiltonian of a spinning test particle in a curved spacetime at linear order in the particle spin. The equations of motion of this unconstrained Hamiltonian coincide with the Mathisson-Papapetrou-Pirani equations. We then use the formalism of Dirac brackets to derive the constrained Hamiltonian and the corresponding phase space algebra in the Newton-Wigner spin supplementary condition, suitably generalized to curved spacetime, and find that the phase space algebra $(\mathbf{q},\mathbf{p},\mathbf{S})$ is canonical at linear order in the particle spin. We provide explicit expressions for this Hamiltonian in a spherically symmetric spacetime, both in isotropic and spherical coordinates, and in the Kerr spacetime in Boyer-Lindquist coordinates. Furthermore, we find that our Hamiltonian, when expanded in post-Newtonian (PN) orders, agrees with the Arnowitt-Deser-Misner canonical Hamiltonian computed in PN theory in the test particle limit. Notably, we recover the known spin-orbit couplings through 2.5PN order and the spin-spin couplings of type $S_{\mathrm{Kerr}}S$ (and $S_{\mathrm{Kerr}}^2$) through 3PN order, $S_{\mathrm{Kerr}}$ being the spin of the Kerr spacetime. Our method allows one to compute the PN Hamiltonian at any order, in the test particle limit and at linear order in the particle spin. As an application we compute it at 3.5PN order.

A spin foam model of three dimensional gravity nonminimally coupled with a scalar field is studied. By discretization of the scalar field, the model is worked out precisely in a purely combinational way. It is shown that the quantum physics of the scalar matter is totally encoded into the modified dynamics of $SU(2)$ spin-network states which describe the quantum geometry of space. It turns out that the physics of the scalar matter coupled with gravity manifested in the low energy scale can be viewed as the phenomena that emerged from this microscopic construction. This gives rise to a radical observation on the issue of the unification of geometry and matter.