The neutralino pair annihilation into two photons in our galactic halo gives a robust dark matter signal, since it would give a quasimonotonic gamma ray. This process is radiatively induced, and the full one-loop calculation was done previously. However, for the heavy W-ino-like or Higgsino-like neutralino, the one-loop cross section violates unitarity; therefore, the higher-order corrections may be important. We construct a nonrelativistic theory for chargino and neutralino two-body states, and estimate all-order QED corrections and two-loop corrections by Z and/or W exchange. We find that the critical mass above which the two-loop contribution is larger than the one-loop one is about 8 TeV $\left[O\right(10\left)\mathrm{}\mathrm{TeV}\right]$ in the limit where the neutralino is W-ino- [Higgsino-]like, respectively. Around and above the critical mass, the all-order Z and/or W exchange must be included to estimate the cross section. On the other hand, the QED corrections depend on the mass difference between the neutralino and chargino. In the W-ino-like limit where the neutralino is highly degenerate with the chargino in mass, we find that QED corrections enhance the pair annihilation cross section by 1.5–2.

We show that in seesaw models of neutrino mass in a SUSY $\mathrm{SO}\left(10\right)\mathrm{}$ context, the observed large mixing in atmospheric neutrinos naturally leads to large $b-s$ transitions. If the associated new $\mathrm{CP}$ phase turns out to be large, this SUSY contribution can drastically affect the $\mathrm{CP}$ violation in some of the B decay channels yielding the $\beta$ and $\gamma$ angles of the unitarity triangle. They can even produce sizable $\mathrm{CP}$ asymmetries in some decay modes which are not $\mathrm{CP}$ violating in the standard model context. Hence the observed large neutrino mixing makes observations of the low energy SUSY effect in some $\mathrm{CP}$ violating decay channels potentially promising in spite of the agreement between the standard model and data in K and B physics so far.

In this paper we investigate the effects due to the mixing of two interpolating currents for ground-state baryons within the framework of heavy quark effective theory using the QCD sum rule approach. Both two-point and three-point sum rules, and thus the mass, coupling constant, and Isgur-Wise function sum rules are considered. It is interesting to contrast those results with each other. Based on the Isgur-Wise functions obtained in this paper, we also analyze the effects of current mixing to $\Lambda$ type and and $\Sigma$ type semileptonic decays ${\Lambda }_b\to {\Lambda }_c\mathcal{l}\overline{\nu },{\Sigma }_b\to {\Sigma }_c\mathcal{l}\overline{\nu },$ and ${\Sigma }_b\to {\Sigma }_c^{*}\mathcal{l}\overline{\nu }.$ Decay widths corresponding to various mixing parameters are obtained and can be compared to the experimental data.

We study compact stars that contain quark matter. We look at the effect of color superconductivity in the quark matter on the nuclear-quark matter transition density, mass-radius relationship, and the density discontinuity at the boundary between nuclear and quark matter. We find that color superconducting quark matter will occur in compact stars at values of the bag constant where ordinary quark matter would not be allowed. We are able to construct “hybrid” stars with a color superconducting quark matter interior and nuclear matter surface, with masses in the range $1.3–{1.6M}_{\odot }$ and radii 8–11 km. Our results are consistent with recent mass-radius limits based on absorption lines from EXO0748-676.

Exclusive photoproduction of all vector mesons by real and virtual photons is considered in the soft dipole Pomeron model. It is emphasized that, the Pomeron in this model being a double Regge pole with an intercept equal to 1, we are led to rising cross sections but the unitarity bounds are not violated. It is shown that all available data for $\rho ,\omega ,\phi ,J/\psi ,$ and ${\rm Y}$ in the region of energies $1.7<~W<~250\mathrm{GeV}$ and photon virtualities $0<~Q^2<~35{\mathrm{GeV}}^2,$ including the differential cross sections in the region of transfer momenta $0<~|t|<~1.6{\mathrm{GeV}}^2,$ are well described by the model.

The relation between the infrared renormalons, the Borel resummation prescriptions, and the analyticity structure of Green’s functions in perturbative QCD is investigated. A specific recently suggested Borel resummation prescription resulted in a principal value and an additional power-suppressed correction that is consistent with operator product expansion. Arguments requiring the finiteness of the result for any power coefficient of the leading infrared renormalon, and consistency in the case of the absence of that renormalon, require that this prescription be modified. The apparently most natural modification leads to the result represented by the principal value. The analytic structure of the amplitude in the complex coupling plane, obtained in this way, is consistent with that obtained in the literature by other methods.

We examine the effect of the Z-boson transverse momentum distribution measured at run-1 of the Fermilab Tevatron on the nonperturbative function of the Collins-Soper-Sterman (CSS) formalism, which resums large logarithmic terms from multiple soft gluon emission in hadron collisions. The inclusion of the Tevatron run-1 Z boson data strongly favors a Gaussian form of the CSS nonperturbative function, when combined with the other low energy Drell-Yan data in a global fit.

We explore the role of Majoron (J) emission in the supernova cooling process, as a source of the upper bound on neutrino-Majoron coupling. We show that the strongest upper bound on the coupling to ${\nu }_e$ comes from the ${\nu }_e{\nu }_e\to J$ process in the core of a supernova. We also find bounds on diagonal couplings of the Majoron to ${\nu }_{\mu \left(\tau \right)}{\nu }_{\mu \left(\tau \right)}$ and on off-diagonal ${\nu }_e{\nu }_{\mu \left(\tau \right)}$ couplings in various regions of the parameter space. We discuss the evaluation of the cross section for four-particle interactions $(\nu \overrightarrow{\nu }\mathrm{JJ}$ and $\nu \overrightarrow{J}\nu J).\mathrm{}$ We show that these are typically dominated by three-particle subprocesses and do not give new independent constraints.

We propose a model for generalized parton distributions of the pion based on the power-law Ansatz for the effective light-cone wave function.

We measure the primary lepton momentum spectrum in $\overline{B}\to X\mathcal{l}\overline{\nu }$ decays, for $p_{\mathcal{l}}>~1.5\mathrm{GeV}/c$ in the B rest frame. From this, we calculate various moments of the spectrum. In particular, we find $R_0\equiv {\int }_{1.7\mathrm{GeV}}(d\Gamma {/dE}_{\mathrm{sl}}{)dE}_{\mathcal{l}}/{\int }_{1.5\mathrm{GeV}}(d\Gamma {/dE}_{\mathrm{sl}}{)dE}_{\mathcal{l}}=0.6187\mathrm{}\pm {0.0014}_{\mathrm{stat}}\pm {0.0016}_{\mathrm{sys}}$ and $R_1\equiv {\int }_{1.5\mathrm{GeV}}{E}_{\mathcal{l}}(d\Gamma {/dE}_{\mathrm{sl}}{)dE}_{\mathcal{l}}/{\int }_{1.5\mathrm{GeV}}(d\Gamma {/dE}_{\mathrm{sl}}{)dE}_{\mathcal{l}}=(1.7810\mathrm{}\pm {0.0007}_{\mathrm{stat}}\pm {0.0009}_{\mathrm{sys}})\mathrm{GeV}.$ We use these moments to determine non-perturbative parameters governing the semileptonic width. In particular, we extract the heavy quark expansion parameters $\overline{\Lambda }=(0.39\mathrm{}\pm {0.03}_{\mathrm{stat}}\pm {0.06}_{\mathrm{sys}}\pm {0.12}_{\mathrm{th}})\mathrm{GeV}$ and ${\lambda }_1=(-0.25\pm {0.02}_{\mathrm{stat}}\pm {0.05}_{\mathrm{sys}}\pm {0.14}_{\mathrm{th}}){\mathrm{GeV}}^2.$ The theoretical constraints used are evaluated through order ${1/M}_B^3$ in the non-perturbative expansion and ${\beta }_0{\alpha }_s^2$ in the perturbative expansion. We use these parameters to extract $|V_{\mathrm{cb}}|$ from the world average of the semileptonic width and find $|V_{\mathrm{cb}}|=(40.8\mathrm{}\pm {0.5}_{{\Gamma }_{\mathrm{sl}}}\pm {0.4}_{({\lambda }_1,\overline{\Lambda }{)}_{\exp }}\pm {0.9}_{\mathrm{th}})\times {10}^{-3}.$ In addition, we extract the short range b-quark mass $m_b^{1\mathrm{S}}=(4.82\mathrm{}\pm {0.07}_{\exp }\pm {0.11}_{\mathrm{th}})\mathrm{GeV}{/c}^2.$ Finally, we discuss the implications of our measurements for the theoretical understanding of inclusive semileptonic processes.

In theories with an infinite extra dimension, free particles localized on the brane can leak out to the extra space. We argue that if there were color confinement in the bulk, electrons would be more able to escape than quarks and protons (which are composed states). Thus, this process generates an electric charge asymmetry on brane matter densities. A primordial charge asymmetry during the big bang nucleosynthesis era is predicted. We use current bounds on this and on electron disappearance to constrain the parameter space of these models. Although the generated asymmetry is generically small, it could be particularly enhanced on large densities as in astrophysical objects, such as massive stars. We suggest the possibility that such an accumulation of charge may be linked, upon supernova collapse, to the formation of a charged black hole and the generation of gamma-ray bursts.

We apply the proposal of Dijkgraaf and Vafa to analyze $\mathcal{N}=1\mathrm{}$ gauge theory with $\mathrm{SO}\left(N\right)\mathrm{}$ and $\mathrm{Sp}\left(N\right)\mathrm{}$ gauge groups with arbitrary tree-level superpotentials using matrix model techniques. We derive the planar and leading nonplanar contributions to the large M $\mathrm{SO}\left(M\right)\mathrm{}$ and $\mathrm{Sp}\left(M\right)\mathrm{}$ matrix model free energy by applying the technology of higher-genus loop equations and by straightforward diagrammatics. The loop equations suggest that the $R{P}^2$ free energy is given as a derivative of the sphere contribution, a relation which we verify diagrammatically. With a refinement of the proposal of Dijkgraaf and Vafa for the effective superpotential, we find agreement with field theory expectations.

We show that the degenerate positive-norm physical propagating fields of the open bosonic string can be gauged to the higher rank fields at the same mass level. As a result, their scattering amplitudes can be determined from those of the higher spin fields. This phenomenon arises from the existence of two types of zero-norm states with the same Young representations as those of the degenerate positive-norm states in the old covariant first quantized (OCFQ) spectrum. This is demonstrated by using the lowest order gauge transformation of Witten’s string field theory (WSFT) up to the fourth massive level (spin-five), and is found to be consistent with conformal field theory calculation based on the first quantized generalized sigma-model approach. In particular, on-shell conditions of zero-norm states in the OCFQ stringy gauge transformation are found to correspond, in a one-to-one manner, to the background ghost fields in off-shell gauge transformation of WSFT. The implication of decoupling of scalar modes on Sen’s conjectures is also briefly discussed.

In a scalar ${\phi }^2\chi$ model, we exactly solve the vertex and $\phi$ propagator Dyson-Schwinger equations under the assumption of a spatially constant (Munczek-Nemirovsky) propagator for the $\chi$ field. Various truncation schemes are also considered.

Chiral phase properties of finite size hadronic systems are investigated within the Nambu–Jona-Lasinio model. Finite size effects are taken into account by making use of the multiple reflection expansion. We find that, for droplets with relatively small baryon numbers, chiral symmetry restoration is enhanced by the finite size effects. However the radius of the stable droplet does not change much, as compared to that without the multiple reflection expansion.

We consider a four-dimensional effective gravity theory arising from a five-dimensional Chern-Simons form together with the Kaluza-Klein ansatz structure and a toroidal compactification to four dimensions. Plane-fronted gravitational and electromagnetic wave solutions in space-times endowed with a cosmological constant term are presented. The solution is a general one and contains three arbitrary functions, one of them being associated with a null electromagnetic field. A particular example with a specific choice of the free functions is also presented.

We outline a phenomenological program for the search of effects induced by (string-motivated) canonical noncommutative spacetime. The tests we propose are based, in analogy with a corresponding program developed over the last few years for the study of Lie-algebra noncommutative spacetimes, on the role of the noncommutativity parameters in the $E\left(p\right)\mathrm{}$ dispersion relation. We focus on the role of deformed dispersion relations in particle-production collision processes, where the noncommutativity parameters would affect the threshold equation, and in the dispersion of gamma rays observed from distant astrophysical sources. We emphasize that the studies here proposed have the advantage of involving particles of relatively high energies, and may therefore be less sensitive to “contamination” (through IR/UV mixing) from the UV sector of the theory. We also explore the possibility that the relevant deformation of the dispersion relations could be responsible for the experimentally observed violations of the GZK cutoff for cosmic rays and could have a role in the observation of hard photons from distant astrophysical sources.

The Bethe-Salpeter equation for Wick-Cutkosky-like models is solved in the dressed ladder approximation. The bare vertex truncation of the Dyson-Schwinger equations for propagators is combined with the dressed ladder Bethe-Salpeter equation for the scalar S-wave bound state amplitudes. With the help of the spectral representation the results are obtained directly in Minkowski space. We give a new analytic formula for the resulting equation simplifying the numerical treatment. The bare ladder approximation of the Bethe-Salpeter equation is compared with the one with dressed ladder. The elastic electromagnetic form factors are calculated within the relativistic impulse approximation.

The tetrad-based equations for vacuum gravity published by Estabrook, Robinson, and Wahlquist are simplified and adapted for numerical relativity. We show that the evolution equations as partial differential equations for the Ricci rotation coefficients constitute a rather simple first-order symmetrizable hyperbolic system, not only for the Nester gauge condition on the acceleration and angular velocity of the tetrad frames considered by Estabrook et al., but also for the Lorentz gauge condition of van Putten and Eardley and for a fixed gauge condition. We introduce a lapse function and a shift vector to allow general coordinate evolution relative to the timelike congruence defined by the tetrad vector field.

Recently, investigations have begun into a holographic duality for two-dimensional de Sitter space. In this paper we evaluate the associated central charge, using a modified version of the canonical Hamiltonian method that was first advocated by Catelani and co-workers. Our computation agrees with that of a prior work (Cadoni et al.), but we argue that the method used here is, perhaps, aesthetically preferable on holographic grounds. We also confirm an agreement between the Cardy and thermodynamic entropy, thus providing further support for the conjectured two-dimensional de Sitter–conformal field theory correspondence.