Precise measurements of the single spin asymmetry $A_N$, and the double spin asymmetry $A_{NN}$, in proton-proton ($pp$) elastic scattering in the region of four-momentum transfer squared $0.001<-t<0.032(\mathrm{GeV}/c{)}^2$ have been performed using a polarized atomic hydrogen gas jet target and the Relativistic Heavy Ion Collider (RHIC) polarized proton beam. We present measurements of $A_N$ and $A_{NN}$ at center-of-mass energies $\sqrt{s}=6.8$ and 13.7 GeV. These spin-dependent observables are sensitive to the poorly known hadronic spin-dependent amplitudes. Comparing $A_N$ at different energies, a $\sqrt{s}$ dependence of the hadronic single spin-flip amplitude is suggested. A hadronic double spin-flip amplitude from the $A_{NN}$ data is consistent with zero within a 2-$\sigma$ level. We also present $\Delta {\sigma }_T$, estimated from the measured $A_{NN}$ data. The results for $\Delta {\sigma }_T$ are consistent with zero. Our results provide significant constraints toward a comprehensive understanding of the reaction mechanism for $pp$ elastic scattering.

We present measurements of the semileptonic decays $B^{-}\to D^0{\tau }^{-}{\overline{\nu }}_{\tau }$, $B^{-}\to D^{*0}{\tau }^{-}{\overline{\nu }}_{\tau }$, ${\overline{B}}^0\to D^{+}{\tau }^{-}{\overline{\nu }}_{\tau }$, and ${\overline{B}}^0\to D^{*+}{\tau }^{-}{\overline{\nu }}_{\tau }$, which are sensitive to non-standard model amplitudes in certain scenarios. The data sample consists of $232\times {10}^6{\rm Y}(4S)\to B\overline{B}$ decays collected with the BABAR detector at the PEP-II $e^{+}{e}^{-}$ collider. We select events with a $D$ or $D^{*}$ meson and a light lepton ($\ell =e$ or $\mu$) recoiling against a fully reconstructed $B$ meson. We perform a fit to the joint distribution of lepton momentum and missing mass squared to distinguish signal $\overline{B}\to D^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }({\tau }^{-}\to {\ell }^{-}{\overline{\nu }}_{\ell }{\nu }_{\tau })$ events from the backgrounds, predominantly $\overline{B}\to D^{(*)}{\ell }^{-}{\overline{\nu }}_{\ell }$. We measure the branching-fraction ratios $R(D)\equiv \mathcal{B}(\overline{B}\to D{\tau }^{-}{\overline{\nu }}_{\tau })/\mathcal{B}(\overline{B}\to D{\ell }^{-}{\overline{\nu }}_{\ell })$ and $R(D^{*})\equiv \mathcal{B}(\overline{B}\to D^{*}{\tau }^{-}{\overline{\nu }}_{\tau })/\mathcal{B}(\overline{B}\to D^{*}{\ell }^{-}{\overline{\nu }}_{\ell })$ and, from a combined fit to $B^{-}$ and ${\overline{B}}^0$ channels, obtain the results $R(D)=(41.6\pm 11.7\pm 5.2)\%$ and $R(D^{*})=(29.7\pm 5.6\pm 1.8)\%$, where the uncertainties are statistical and systematic. Normalizing to measured $B^{-}\to D^{(*)0}{\ell }^{-}{\overline{\nu }}_{\ell }$ branching fractions, we obtain $\mathcal{B}(\overline{B}\to D{\tau }^{-}{\overline{\nu }}_{\tau })=(0.86\pm 0.24\pm 0.11\pm 0.06)\%$ and $\mathcal{B}(\overline{B}\to D^{*}{\tau }^{-}{\overline{\nu }}_{\tau })=(1.62\pm 0.31\pm 0.10\pm 0.05)\%$, where the additional third uncertainty is from the normalization mode. We also present, for the first time, distributions of the lepton momentum, $|{\mathbf{p}}_{\ell }^{*}|$, and the squared momentum transfer, $q^2$.

We revisit a propagating torsion gravity theory obtained by introducing a field coupled to the Holst term in the first-order Einstein-Cartan action. The resulting theory has second-order field equations, no adjustable coupling constants, and one more propagating degree of freedom as compared to general relativity. When no fermions are present the theory is known to be equivalent to that of a single massless scalar field canonically coupled to gravity. We extend this result to the case with fermions and obtain an effective interaction between the scalar field and the fermionic currents. We also describe a version of the theory with a potential for the scalar field and discuss whether it can be interpreted as the inflaton.

We consider a stabilized Randall Sundrum 1 model in the energy range below the direct production of Kaluza-Klein (KK) states. In this range, we work out the effective Lagrangian due to exchange of heavy KK tensor graviton and scalar radion states and compute explicitly the corresponding effective coupling constants. As an example, the Drell-Yan lepton pair production at the Tevatron and the LHC is analyzed in two situations, when the first KK resonance is too heavy to be directly detected at the colliders, and when the first KK resonance is visible, but other states are still too heavy. It is shown that in both cases the contribution from the KK invisible tower leads to a modification of final particles distributions. In particular, for the second case a nontrivial interference between the first KK mode and the rest KK tower takes place. Expected 95% C.L. limits for model parameters for the Tevatron and the LHC are given. In the Appendix, useful formulas for the cross sections and distributions of various new $2\to 2$ processes via heavy KK tower exchange are presented, the new formulas containing nonzero particle masses for final state fermions and bosons. The formulas and numerical results are obtained by means of the CompHEP code, in which all new effective interactions are implemented providing a tool for simulation of corresponding events and a more detailed analysis.

We examine the structure of a cosmic string endowed with two Abelian neutral currents, associated with two global $U(1)$ symmetries. We first resolve the microstructure and show that it depends on two state parameters, namely, the squares of the phase gradients of the current carriers. We then provide a macroscopic description for such a string and show that it depends on an additional Lorentz-invariant state parameter that relates the two currents. We find that in most of the parameter space, the two-current string is essentially equivalent to the single-current-carrying string; i.e., only one field condenses onto the defect. In the regions where two currents are present, we find that as far as stability is concerned, one can approximate the dynamics with good accuracy using an analytic model based on either a logarithmic (on the electric side, i.e., for timelike currents) or a rational (on the magnetic side, i.e., for spacelike currents) world sheet Lagrangian. We end up by generalizing to the $N$ current case.

In this letter, we suggest that a nearby clump of 600–1000 GeV neutralinos may be responsible for the excesses recently observed in the cosmic ray positron and electron spectra by the PAMELA and ATIC experiments. Although neutralino dark matter annihilating throughout the halo of the Milky Way is predicted to produce a softer spectrum than is observed, and violate constraints from cosmic ray antiproton measurements, a large nearby (within 1–2 kiloparsecs of the Solar System) clump of annihilating neutralinos can lead to a spectrum which is consistent with PAMELA and ATIC, while also producing an acceptable antiproton flux. Furthermore, the presence of a large dark matter clump can potentially accommodate the very large annihilation rate required to produce the PAMELA and ATIC signals. We estimate the probability of a sufficiently large clump being present to be $\sim {10}^{-3}$ or less.

We investigate the constraints that can be set from big bang nucleosynthesis on two classes of models: extended quintessence and scalar-tensor theories of gravity in which the equivalence principle between standard matter and dark matter is violated. In the latter case, and for a massless dilaton with quadratic couplings, the phase space of theories is investigated. We delineate those theories where attraction toward general relativity occurs. It is shown that big bang nucleosynthesis sets more stringent constraints than those obtained from Solar System tests.

This article completes a former work where part of the $\mathcal{O}(p^6)$ low-energy constants entering in the $\pi \pi$ scattering were estimated. Some resonance contributions were missed in former calculations and slight differences appeared with respect to our outcome. Here, we provide the full results for all the contributing $\mathcal{O}(p^6)$ couplings. We also perform a reanalysis of the hadronic inputs used for the estimation (resonance masses, widths…). Their reliability was checked together with the impact of the input uncertainties on the determinations of the chiral couplings and the scattering lengths $a_J^I$. Our outcome is found to be in agreement with former works though with slightly larger errors. However, the effect in the final values of the $a_J^I$ is negligible after combining them with the other uncertainties. Based on this consistency, we conclude that the previous scattering length determinations seem to be rather solid and reliable, with the $\mathcal{O}(p^6)$ low energy constants quite under control. Nevertheless, the uncertainties found in the present work point out the limitation on further improvements unless the precision of the $\mathcal{O}(p^6)$ couplings is properly increased.

We extend the study of lowest moments, $⟨x⟩$ and $⟨x^2⟩$, of the parton distribution function of the nucleon to include those of the sea quarks; this entails a disconnected insertion calculation in lattice QCD. This is carried out on a ${16}^3\times 24$ quenched lattice with Wilson fermion. The quark loops are calculated with $Z_2$ noise vectors and unbiased subtractions, and multiple nucleon sources are employed to reduce the statistical errors. We obtain $5\sigma$ signals for $⟨x⟩$ for the $u$, $d$, and $s$ quarks, but $⟨x^2⟩$ is consistent with zero within errors. We provide results for both the connected and disconnected insertions. The perturbatively renormalized $⟨x⟩$ for the strange quark at $\mu =2\mathrm{GeV}$ is $⟨x{⟩}_{s+\overline{s}}=0.027\pm 0.006$ which is consistent with the experimental result. The ratio of $⟨x⟩$ for $s$ vs $u/d$ in the disconnected insertion with quark loops is calculated to be $0.88\pm 0.07$. This is about twice as large as the phenomenologically fitted $\frac{⟨x{⟩}_{s+\overline{s}}}{⟨x{⟩}_{\overline{u}}+⟨x{⟩}_{\overline{d}}}$ from experiments where $\overline{u}$ and $\overline{d}$ include both the connected and disconnected insertion parts. We discuss the source and implication of this difference.

The $X(3872)$ with quantum numbers $J^{PC}=1^{++}$ is considered as a composite hadronic state comprised of the dominant molecular $D^0{D}^{*0}$ component and other hadronic pairs—$D^{\pm }{D}^{*\mp }$, $J/\psi \omega$, and $J/\psi \rho$. Applying the compositeness condition we constrain the couplings of the $X(3872)$ to its constituents. We calculate two- and three-body hadronic decays of the $X(3872)$ to charmonium states ${\chi }_{cJ}$ and pions using a phenomenological Lagrangian approach. Next using the estimated $XJ/\psi \omega$ and $XJ/\psi \rho$ couplings we calculate the widths of $X(3872)\to J/\psi +h$ transitions, where $h={\pi }^{+}{\pi }^{-}$, ${\pi }^{+}{\pi }^{-}{\pi }^0$, ${\pi }^0\gamma$, and $\gamma$. The obtained results for the decay pattern of the $X(3872)$ in a molecular interpretation could be useful for running and planned experiments.

We calculate the primordial black hole (PBH) mass spectrum produced from a collapse of the primordial density fluctuations in the early Universe using, as an input, several theoretical models giving the curvature perturbation power spectra ${\mathcal{P}}_{\mathcal{R}}(k)$ with large ($\sim {10}^{-2}–{10}^{-1}$) values at some scale of comoving wave numbers $k$. In the calculation we take into account the explicit dependence of gravitational (Bardeen) potential on time. Using the PBH mass spectra, we further calculate the neutrino and photon energy spectra in extragalactic space from evaporation of light PBHs, and the energy density fraction contained in PBHs today (for heavier PBHs). We obtain the constraints on the model parameters using available experimental data (including data on neutrino and photon cosmic backgrounds). We briefly discuss the possibility that the observed 511 keV line from the Galactic center is produced by annihilation of positrons evaporated by PBHs.

Metric $f(R)$ gravity theories are conformally equivalent to models of quintessence in which matter is coupled to dark energy. We derive a condition for a stable tracker solution for metric $f(R)$ gravity in the Einstein frame. We find that tracker solutions with $-0.361<{\omega }_{\phi }<1$ exist if $0<\Gamma <0.217$ and $\frac{d}{dt}\ln f^{\prime }(\tilde{R})>0$, where $\Gamma =\frac{V_{\phi \phi }V}{V_{\phi }^2}$ is a dimensionless function, ${\omega }_{\phi }$ is the equation of state parameter of the scalar field, and $\tilde{R}$ refers to the Jordan frame’s curvature scalar. Also, we show that there exists $f(\tilde{R})$ gravity models which have tracking behavior in the Einstein frame and so the curvature of space-time is decreasing with time while they lead to the solutions in the Jordan frame that the curvature of space-time can be increasing with time.

We show that the theory of Breit-Wigner resonances can be used as an efficient numerical tool to compute black hole quasinormal modes. For illustration, we focus on the Schwarzschild anti–de Sitter (SAdS) spacetime. The resonance method is better suited to small SAdS black holes than the traditional series expansion method, allowing us to confirm that the damping time scale of small SAdS black holes for scalar and gravitational fields is proportional to $r_{+}^{-2l-2}$, where $r_{+}$ is the horizon radius. The proportionality coefficients are in good agreement with analytic calculations. We also examine the eikonal limit of SAdS quasinormal modes, confirming quantitatively Festuccia and Liu’s [arXiv:0811.1033] prediction of the existence of very long-lived modes. Our results are particularly relevant for the AdS/CFT correspondence, since long-lived modes presumably dominate the decay time scale of the perturbations.

Several supersymmetric models with extended gauge structures, motivated by either grand unification or by neutrino mass generation, predict light doubly charged Higgsinos. In this work we study the signals of doubly charged Higgsinos at the Tevatron in both pair- and single-production modes, and show that it is possible, especially from the events containing same-sign same-flavor isolated leptons, to disentangle the effects of doubly charged Higgsinos in the Tevatron data.

We present results for all leading-twist azimuthal spin asymmetries in semi-inclusive lepton-nucleon deep-inelastic scattering due to T-even transverse-momentum dependent parton distribution functions on the basis of a light-cone constituent quark model. Attention is paid to discuss the range of applicability of the model, especially with regard to the scale dependence of the observables and the transverse-momentum dependence of the distributions. We find good agreement with available experimental data and present predictions to be further tested by future CLAS, COMPASS, and HERMES data.

We perform a detailed study of the Higgs production and decay, when Higgs is emitted from the black holes produced in proton-proton collisions at the Large Hadron Collider. We show that black hole production can significantly enhance the signal for the Higgs search at the LHC. We evaluate rapidity distribution of diphotons and transverse momentum distribution of bottom quarks, photons, tau leptons, top quarks, and $W$ bosons from Higgs decay, when Higgs is emitted from the black hole and also in the case when these particles are produced directly from the black hole evaporation. We compare our results with the standard model backgrounds. We find that Higgs production from black holes is dominant over standard model production for $p_T^H>100\mathrm{GeV}$, when $M_P=1\mathrm{TeV}$. Diphotons from Higgs, when Higgs is produced from evaporation of black holes, are dominant over the standard model prediction, for diphoton rapidity $|y_{\gamma \gamma }|\le 1$, while bottom quarks are dominant over QCD background for large bottom quark transverse momentum, $p_T^b>300\mathrm{GeV}$, when $M_P=1\mathrm{TeV}$. We show that measurements of the photon and bottom quark transverse momentum distribution can provide valuable information about the value of the fundamental Planck scale. We also propose a new signal for black hole production at the LHC, an onset of increasing transverse momentum distribution of bottom quarks with large transverse momentum.

We calculate the next-to-leading order perturbative QCD corrections to the transverse momentum weighted single transverse spin asymmetry in Drell-Yan lepton pair production in hadronic collisions. We identify the splitting function relevant for the scale evolution of the twist-three quark-gluon correlation function. We comment on the consequences of our results for phenomenology.

We advocate charmed-hadron inclusive hadroproduction as a laboratory to probe intrinsic charm (IC) inside the colliding hadrons. Working at next-to-leading order in the general-mass variable-flavor-number scheme endowed with nonperturbative fragmentation functions recently extracted from a global fit to $e^{+}{e}^{-}$ annihilation data from KEKB, CESR, and LEP1, we first assess the sensitivity of Tevatron data of $D^0$, $D^{+}$, and $D^{*+}$ inclusive production to the IC parametrizations provided by Pumplin et al. We then argue that similar data from $pp$ collisions at RHIC would have the potential to discriminate between different IC models provided they reach out to sufficiently large values of transverse momentum.

A photon exhibits a tiny anomalous magnetic moment ${\mu }_{\gamma }$ due to its interaction with an external constant magnetic field in vacuum through the virtual electron-positron background. It is paramagnetic (${\mu }_{\gamma }>0$) in the whole region of transparency, i.e., below the first threshold energy for pair creation, and has a maximum near this threshold. The photon magnetic moment is different for eigenmodes polarized along and perpendicular to the magnetic field. Explicit expressions are given for ${\mu }_{\gamma }$ for the cases of photon energies smaller than and closer to the first pair creation threshold. The region beyond the first threshold is briefly discussed.