The common view that structure functions measured in deep inelastic lepton scattering are determined by the probability of finding quarks and gluons in the target is not correct in gauge theory. We show that gluon exchange between the fast, outgoing partons and target spectators, which is usually assumed to be an irrelevant gauge artifact, affects the leading twist structure functions in a profound way. This observation removes the apparent contradiction between the projectile (eikonal) and target (parton model) views of diffractive and small $x_B$ phenomena. The diffractive scattering of the fast outgoing quarks on spectators in the target causes shadowing in the DIS cross section. Thus the depletion of the nuclear structure functions is not intrinsic to the wave function of the nucleus, but is a coherent effect arising from the destructive interference of diffractive channels induced by final state interactions. This is consistent with the Glauber-Gribov interpretation of shadowing as a rescattering effect.

It is well known that waves propagating under the influence of a scattering potential develop “tails.” However, the study of late-time tails has so far been restricted to time-independent backgrounds. In this paper, we explore the late-time evolution of spherical waves propagating under the influence of a time-dependent scattering potential. It is shown that the tail structure is modified due to the temporal dependence of the potential. The analytical results are confirmed by numerical calculations.

It has long been known that strings wound around incontractible cycles can play a vital role in cosmology. In particular, in a spacetime with toroidal spatial hypersurfaces, the dynamics of the winding modes may help yield three large spatial dimensions. However, toroidal compactifications are phenomenologically unrealistic. In this paper we therefore take a first step toward extending these cosmological considerations to D-dimensional toroidal orbifolds. We use numerical simulation to study the time scales over which “pseudo-wound” strings unwind on these orbifolds with trivial fundamental group. We show that pseudo-wound strings can persist for many “Hubble times” in some of these spaces, suggesting that they may affect the dynamics in the same way as genuinely wound strings. We also outline some possible extensions that include higher-dimensional wrapped branes.

We study a new baryogenesis scenario in a class of braneworld models with low fundamental scale, which typically have difficulty with baryogenesis. The scenario is characterized by its minimal nature: the field content is that of the standard model and all interactions consistent with the gauge symmetry are admitted. Baryon number is violated via a dimension-6 proton decay operator, suppressed today by the mechanism of quark-lepton separation in extra dimensions; we assume that this operator was unsuppressed in the early Universe due to a time-dependent quark-lepton separation. The source of $\mathrm{CP}$ violation is the CKM matrix, in combination with the dimension-6 operators. We find that almost independently of cosmology, sufficient baryogenesis is nearly impossible in such a scenario if the fundamental scale is above 100 TeV, as required by an unsuppressed neutron-antineutron oscillation operator. The only exception producing sufficient baryon asymmetry is a scenario involving out-of-equilibrium c quarks interacting with equilibrium b quarks.

We examine Sen’s descent relations among (non-) Bogomol’nyi-Prasad-Sommerfield (BPS) D-branes by using low-energy effective field theories of the $\mathrm{D}p\mathrm{D}¯p$ system. We find that the fluctuation around the kink solution reproduces the low-energy matter content on a non-BPS $\mathrm{D}\left(p-1\right)$-brane. The effective action for these fluctuation modes turns out to be a generalization of the Minahan-Zwiebach model. In addition, it is shown that the fluctuations around the vortex solution consist of massless fields on a BPS $\mathrm{D}\left(p-2\right)$-brane and they are subject to the Dirac-Born-Infeld action. We find the universality that the above results do not refer to particular forms of the effective action.

Extending previous work, we calculate the fermionic spectrum of two-dimensional QCD $\left({\mathrm{QCD}}_2\right)$ in the formulation with ${SU(N}_c)$ currents. Together with the results in the bosonic sector this allows us to address the as yet unresolved task of finding the single-particle states of this theory as a function of the ratio of the numbers of flavors and colors, $\lambda {=N}_f{/N}_c,$ anew. We construct the Hamiltonian matrix in the DLCQ formulation as an algebraic function of the harmonic resolution K and the continuous parameter λ in the Veneziano limit. We find that the fermion momentum is a function of λ in the discrete approach. A universality, existing only in two dimensions, dictates that the well-known ’t Hooft and large $N_f$ spectra be reproduced in the limits $\overrightarrow{\lambda }0$ and ∞, which we confirm. We identify their single-particle content which is surprisingly the same as in the bosonic sectors. All multiparticle states are classified in terms of their constituents. These findings allow for an identification of the lowest single particles of the adjoint theory. While we do not succeed in interpreting this spectrum completely, evidence is presented for the conjecture that adjoint ${\mathrm{QCD}}_2$ has a bosonic and an independent fermionic Regge trajectory of single-particle states.

In the quest to develop viable designs for third-generation optical interferometric gravitational-wave detectors (e.g. LIGO-III and EURO), one strategy is to monitor the relative momentum or speed of the test-mass mirrors rather than monitoring their relative position. This paper describes and analyzes the most straightforward design for a speed meter interferometer that accomplishes this—a design (due to Braginsky, Gorodetsky, Khalili and Thorne) that is analogous to a microwave-cavity speed meter conceived by Braginsky and Khalili. A mathematical mapping between the microwave speed meter and the optical interferometric speed meter is developed and is used to show [in accord with the speed being a quantum nondemolition observable] that in principle the interferometric speed meter can beat the gravitational-wave standard quantum limit (SQL) by an arbitrarily large amount, over an arbitrarily wide range of frequencies, and can do so without the use of squeezed vacuum or any auxiliary filter cavities at the interferometer’s input or output. However, in practice, to reach or beat the SQL, this specific speed meter requires exorbitantly high input light power. The physical reason for this is explored, along with other issues such as constraints on performance due to optical dissipation. This analysis forms a foundation for ongoing attempts to develop a more practical variant of an interferometric speed meter and to combine the speed meter concept with other ideas to yield a promising LIGO-III/EURO interferometer design that entails low laser power.

We analyze the sensitivity to physics beyond the standard model of T-odd correlations in $K_{l4\mathrm{}}$ decays, which do not involve lepton polarization. We show that a combined analysis of $K_{\mu 4}^{+}$ and $K_{\mu 4}^{-}$ decays can lead to new constraints about $\mathrm{CP}$ violation in $\Delta S=1\mathrm{}$ charged-current interactions, complementary to those obtained from the transverse muon polarization in $K_{\mu 3}$ and of comparable accuracy.

We examine the gluon propagator in the Laplacian gauge in quenched lattice QCD as a function of the number of colors. We observe a weak dependence on $N_c$ over the whole momentum range. This implies an almost $N_c$-independent gluon pole mass in units of the string tension.

We investigate dynamical chiral symmetry breaking in vectorlike gauge theories in D dimensions with $D-4$ compactified extra dimensions, based on the gap equation (Schwinger-Dyson equation) and the effective potential for the bulk gauge theories within the improved ladder approximation. The nonlocal gauge fixing method is adopted so as to keep the ladder approximation consistent with the Ward-Takahashi identities. Using the one-loop modified minimal subtraction scheme $\left(\overline{\mathrm{MS}}\right)$ gauge coupling of the truncated Kaluza-Klein effective theory, which has a nontrivial ultraviolet fixed point $g_{*}$ for the (dimensionless) bulk gauge coupling $ĝ,$ we find that there exists a critical number of flavors $N_f^{\mathrm{crit}}$ $[\simeq 4.2,1.8$ for $D=6,8\mathrm{}$ for SU(3) gauge theory]. For $N_f>N_f^{\mathrm{crit}},$ the dynamical chiral symmetry breaking takes place not only in the “strong-coupling phase” $(ĝ>g_{*})$ but also in the “weak-coupling phase” $(ĝ<g_{*})$ when the cutoff is large enough. For $N_f<N_f^{\mathrm{crit}},$ on the other hand, only the strong-coupling phase is a broken phase and we can formally define a continuum (infinite cutoff) limit, so that the physics is insensitive to the cutoff in this case. We also perform a similar analysis using the one-loop “effective gauge coupling.” We find that $N_f^{\mathrm{crit}}$ turns out to be a value similar to that of the $\overline{\mathrm{MS}}$ case, notwithstanding the enhancement of the coupling compared with that of the $\overline{\mathrm{MS}}.$

The static three-quark (3Q) potential is studied in detail using SU(3) lattice QCD with ${12}^3\times 24$ at $\beta =5.7\mathrm{}$ and ${16}^3\times 32$ at $\beta =5.8,6.0\mathrm{}$ at the quenched level. For more than 300 different patterns of the 3Q systems, we perform the accurate measurement of the 3Q Wilson loop with the smearing method, which reduces excited-state contaminations, and present the lattice QCD data of the 3Q ground-state potential $V_{3\mathrm{Q}}.$ We perform the detailed fit analysis on $V_{3\mathrm{Q}}$ in terms of the Y Ansatz both with the continuum Coulomb potential and with the lattice Coulomb potential, and find that the lattice QCD data of the 3Q potential $V_{3\mathrm{Q}}$ are well reproduced within a few percent deviation by the sum of a constant, the two-body Coulomb term and the three-body linear confinement term ${\sigma }_{3\mathrm{Q}}{L}_{\min },$ with $L_{\min }$ the minimal value of the total length of color flux tubes linking the three quarks. From the comparison with the $\mathrm{Q}-\overline{\mathrm{Q}}$ potential, we find a universality of the string tension as ${\sigma }_{3\mathrm{Q}}\simeq {\sigma }_{\mathrm{Q}\overline{\mathrm{Q}}}$ and the one-gluon-exchange result for the Coulomb coefficients as $A_{3\mathrm{Q}}\simeq \frac{1}{2}{A}_{\mathrm{Q}\overline{\mathrm{Q}}}.$ We investigate also the several fit analyses with the various Ansätze: the Y Ansatz with the Yukawa potential, the $\Delta$ Ansatz and a more general Ansatz including the Y and the $\Delta$ Ansätze in some limits. All these fit analyses support the Y Ansatz on the confinement part in the 3Q potential $V_{3\mathrm{Q}},$ although $V_{3\mathrm{Q}}$ seems to be approximated by the $\Delta$ Ansatz with ${\sigma }_{\Delta }\simeq 0.53\sigma .$

We extend our study of the gluon propagator in quenched lattice QCD using the Laplacian gauge to a finer lattice. We verify the existence of a pole mass as we take the continuum limit and deduce a value of $\sim {600}_{-30}^{+150\mathrm{}}\hspace{0.5em}\mathrm{MeV}$ for this pole mass. We find a finite value of $\left[454\right(5)\mathrm{}\hspace{0.5em}\mathrm{MeV}{]}^{-2}$ for the renormalized zero-momentum propagator, in agreement with results on coarser lattices.

We give upper bounds for transverse double-spin asymmetries in polarized proton-proton collisions by saturating the positivity constraint for the transversity densities at a low hadronic resolution scale. We consider prompt photon, jet, pion, and heavy flavor production at the BNL Relativistic Heavy Ion Collider (RHIC). Estimates of the expected statistical accuracy for such measurements are presented, taking into account the acceptance of the RHIC detectors.

An SU(3) chiral Lagrangian for the lightest decuplet of baryons is constructed on a discrete lattice of spacetime points, and is added to an existing lattice Lagrangian for the lightest octets of mesons and baryons. A nonzero lattice spacing renders all loop integrations finite, and the continuum limit of any physical observable is identical to the result obtained from dimensional regularization. Chiral symmetry and gauge invariance are preserved even at nonzero lattice spacing. Specific calculations discussed here include the nonrenormalization of a conserved vector current, the magnetic moments of octet baryons, and the $\pi N$ and $\mathrm{KN}$ sigma terms that relate to the nucleon’s strangeness content. The quantitative difference between physics at a nonzero lattice spacing and physics in the continuum limit is easily computed, and it represents an expectation for the size of discretization errors in corresponding lattice QCD simulations.

We estimate the intrinsic charm contributions to the quark flavor and spin observables of the nucleon in the SU(4) quark meson fluctuation model. In this model, the charm or anticharm resides in the charmed mesons created by the nonperturbative quantum quark-meson fluctuations. The intrinsic charm content in the proton, $2\overline{c}/\sum (q+\overline{q})\simeq 0.011\pm 0.008,$ is almost one order of magnitude smaller than the intrinsic strange content. The intrinsic charm helicity is also small and negative, $\Delta c\simeq -(0.009\mathrm{}\pm 0.006).$ The fraction of the total quark helicity carried by the charm is $|\Delta c/\Delta \Sigma |\simeq 0.021\pm \mathrm{0.014.}$ The ratio of the charm with positive helicity to that with negative helicity is $c_{\uparrow }{/c}_{\downarrow }=35/67.\mathrm{}$ For the intrinsic strange component, one has $s_{\uparrow }{/s}_{\downarrow }\simeq 7/13.$ A detailed comparison of our predictions with data and other models or analyses is given. The intrinsic charm contribution to the Ellis-Jaffe sum rule is also discussed.

In this paper, we reexamine the new physics contributions to seven well measured $\overrightarrow{B}\mathrm{PP}$ decays in the standard model (SM) and the general two-Higgs-doublet model (model III) and compare the theoretical predictions with the new data. Within the considered parameter space we find that (a) the measurements of the branching ratios for $\overrightarrow{B}{\pi }^{+}{\pi }^{-},K^{-}{\pi }^{+},$ and $K^0{\pi }^{+}$ lead to a strong constraint on the form factor $F_0^{B\pi }\mathrm{}\left(0\right):$ $F_0^{B\pi }\mathrm{}\left(0\right)=0.24\mathrm{}\pm 0.03,$ and (b) the new physics enhancements to the penguin-dominated $\overrightarrow{B}K\pi$ and $K{\eta }^{\prime }$ decays are significant in size, $\sim (40\mathrm{}–65)\%$ with respect to the SM predictions, and play an important role in restoring the consistency between the data and theory.

We apply the picture proposed in a recent Letter for transverse hyperon polarization in unpolarized hadron-hadron collisions to the exclusive process $e^{-}\overrightarrow{p}{e}^{-}\mathrm{HK}$ such as $e^{-}\overrightarrow{p}{e}^{-}\Lambda K^{+},$ $e^{-}\overrightarrow{p}{e}^{-}{\Sigma }^{+}{K}^0,$ or $e^{-}\overrightarrow{p}{e}^{-}{\Sigma }^0{K}^{+},$ or the similar process $e^{-}\overrightarrow{p}{e}^{-}n{\pi }^{+}$ with longitudinally polarized electron beams. We present the predictions for the longitudinal polarizations of the hyperons or neutron in these reactions, which can be used as further tests of the picture.

We study the possibility of spontaneous $\mathrm{CP}$ violation in string models with the dilaton field stabilized at a phenomenologically acceptable value. We consider three mechanisms to stabilize the dilaton: multiple gaugino condensates, a nonperturbative Kähler potential, and a superpotential based on S duality, and analyze consequent $\mathrm{CP}$ phases in the soft supersymmetry (SUSY) breaking terms. Because of the nonuniversality forced upon the theory by requiring a nontrivial Cabibbo-Kobayashi-Maskawa phase, the electric dipole moment problem becomes more severe. Even if there are no complex phases in the vacuum expectation values of the SUSY breaking fields, the electric dipole moments are overproduced by orders of magnitude. We also address the question of the modular invariance of the physical $\mathrm{CP}$ phases.

We present results from a numerical study of bound state wave functions in the $\mathrm{}(2+1)\mathrm{}$-dimensional Gross-Neveu model with staggered lattice fermions at both zero and nonzero temperature. Mesonic channels with varying quantum numbers are identified and analyzed. In the strongly coupled chirally broken phase at $T=0\mathrm{}$ the wave functions expose effects due to varying the interaction strength more effectively than straightforward spectroscopy. In the weakly coupled chirally restored phase information on fermion-antifermion scattering is recovered. In the hot chirally restored phase we find evidence for a screened interaction. The $T=0\mathrm{}$ chirally symmetric phase is most readily distinguished from the symmetric phase at high T via the fermion dispersion relation.