arXiv.org: High-Energy Physics: Phenomenology

hep-ph updates on arXiv.org

• Nonleptonic $B$ meson decays in collinear pQCD at twist-3: Effects of dynamical masses of gluons and quarks. (arXiv:1007.5072v1 [hep-ph])
  

  We compute the amplitudes for non-leptonic annihilation decays of $B$ mesons into two particles within the pQCD collinear approach. The end point divergences are regulated with the help of an infrared finite gluon propagator characterized by a non-perturbative dynamical gluon mass consistent with recent lattice simulations. The divergences at twist-3 are regulated by a dynamical quark mass. Our results fit quite well the existent data of $B^0\to D_s^-K^+$ and $B^0\to D_s^{-*}\bar{K}^+$ for the expected range of dynamical gluon masses. We also make predictions for the rare decays $\bar{B}^0\to K^-K^+$, $\bar{B}^0_s\to \pi^-\pi^+,\pi^0\pi^0$, $B^+\to D_s^{(*)+}\bar{K}^0$, $B^0\to D_s^{\pm(*)} K^\mp$ and $B_s^0\to D^{\pm(*)} \pi^\mp, D^0\pi^0$.

  
  
  
• Inverse see-saw, leptogenesis, observable proton decay and $\Delta^{\pm\pm}_{\rm R}$ in SUSY SO(10) with heavy W_R. (arXiv:1007.5085v1 [hep-ph])
  

  We explore the prospects of low-scale leptogenesis in a class of supersymmetric SO(10) models using singlet neutrinos and the Higgs representations $126_H \oplus \overline{126}_H$ as well as $16_H \oplus \overline{16}_H$. A singlet neutrino, which we show can be as light as 10^5-10^6 GeV, decays through its small mixings with right-handed (RH) neutrinos creating a lepton asymmetry which is explicitly shown to be flavor dependent. While the doublet vacuum expectation value (vev) in $\overline{16}_H$ triggers the generation of desired mixings, it also induces a large RH triplet vev that breaks the left-right intermediate gauge symmetry and gives large right-handed neutrino masses. Manifest unification of gauge couplings and generation of heavy RH neutrino masses are achieved by purely renormalizable interactions. The canonical (Type-I) see-saw contributions to the light neutrino mass matrix cancel out while the Type-II see-saw contribution is negligible. Determining the parameters of the dominant inverse see-saw formula by using the underlying quark-lepton symmetry and neutrino oscillation data, we show how leptogenesis under the gravitino constraint is successfully implemented. The model is found to work for hierarchical as well as inverted hierarchical light neutrino masses. Testable predictions of the model are RH doubly charged Higgs bosons which may be leptophilic and accessible to the Tevatron, LHC or a linear collider. In a model-independent manner, the Drell-Yan pair production cross section at Tevatron or LHC is shown to be bounded between 59%-79% of their left-handed counterparts with same mass. In contrast to single-step breaking SUSY GUTs, which predict a long proton lifetime for the decay $p \to e^+\pi^0$, here this lifetime is substantially reduced, bringing it within one order of the current experimental limit.

  
  
  
• The Golden Point of No-Scale and No-Parameter ${\cal F}$-$SU(5)$. (arXiv:1007.5100v1 [hep-ph])
  

  The ${\cal F}$-lipped $SU(5)\times U(1)_X$ Grand Unified Theory (GUT) supplemented by TeV-scale vector-like particles from ${\cal F}$-theory, together dubbed ${\cal F}$-$SU(5)$, offers a natural multi-phase unification process which suggests an elegant implementation of the No-Scale Supergravity boundary conditions at the unification scale $M_{\cal F} \simeq 7 \times 10^{17}$~GeV. Enforcing the No-Scale boundary conditions, including $B_\mu(M_{\cal F})=0$ on the Higgs bilinear soft term, with the precision 7-year WMAP value on the dark matter relic density isolates a highly constrained ``golden point'' located near $M_{1/2} = 455$~GeV and $\tan \beta = 15$ in the $\tan\beta-M_{1/2}$ plane, which simultaneously satisfies all known experiments, and moreover corresponds to an imminently observable proton decay rate. Because the universal gaugino mass is actually determined from established low energy data via Renormalization Group Equation (RGE) running, there are no surviving arbitrary scale parameters in the present model.

  
  
  
• Gravitational Collapse of Dark Energy Field Configurations. (arXiv:1007.5118v1 [hep-ph])
  

  It is now a well established fact based on several observations that we live in a Universe dominated by dark energy. The most natural candidates for dark energy are fields in curved space-time. We develop the formalism to study the gravitational collapse of fields given any general potential. We apply this formalism to models of dark energy motivated by particle physics considerations. We solve the resulting evolution equations which determine the time evolution of field configurations as well as the dynamics of spacetime.

  
  
  
• Delta Gamma_d: A Forgotten Null Test of the Standard Model. (arXiv:1007.5135v1 [hep-ph])
  

  The recent measurement of an anomalous like-sign dimuon asymmetry by the D0 collaboration has prompted theoretical speculation on possible sources of physics beyond the Standard Model that may affect lifetimes and lifetime differences in neutral B meson systems. One observable that deserves closer attention is the width difference in the B_d system, Delta Gamma_d. Since the Standard Model prediction for this quantity is well below 1%, it serves as a ``null test'' whereby the measurement of a larger value would cleanly reveal the presence of new physics. Methods to measure Delta Gamma_d at current and future experiments are reviewed and an attractive new approach is proposed.

  
  
  
• Scale-dependence of Non-Gaussianity in the Curvaton Model. (arXiv:1007.5148v1 [astro-ph.CO])
  

  We investigate the scale-dependence of f_NL in the self-interacting curvaton model. We show that the scale-dependence, encoded in the spectral index n_{f_NL}, can be observable by future cosmic microwave background observations, such as CMBpol, in a significant part of the parameter space of the model. We point out that together with information about the trispectrum g_NL, the self-interacting curvaton model parameters could be completely fixed by observations. We also discuss the scale-dependence of g_NL and its implications for the curvaton model, arguing that it could provide a complementary probe in cases where the theoretical value of n_{f_NL} is below observational sensitivity.

  
  
  
• Constraint on the gravitino mass in hybrid inflation. (arXiv:1007.5152v1 [hep-ph])
  

  We revisit the F-term hybrid inflation model in supergravity. In particular, we point out that a constant term in the superpotential has significant effects on the inflaton dynamics. It is shown that the hybrid inflation model suffers from several potential problems: tuning of the initial condition, gravitino overproduction and formation of cosmic strings, for both minimal and non-minimal Kahler potentials. These problems can only be avoided in gauge-mediated SUSY breaking models where the gravitino is relatively light and the constant term in the superpotential is not important. Implications on the non-thermal leptogenesis scenario are also described.

  
  
  
• eta_c production at the Large Hadron Collider. (arXiv:1007.5163v1 [hep-ph])
  

  We have studied the production of the 1S_0 charmonium state, eta_c, at the Large Hadron Collider (LHC) in the framework of Non-Relativistic Quantum Chromodynamics (NRQCD) using heavy-quark symmetry. We find that NRQCD predicts a large production cross-section for this resonance at the LHC even after taking account the small branching ratio of eta_c into two photons. We show that it will be possible to test NRQCD through its predictions for eta_c, with the statistics that will be achieved at the early stage of the LHC, running at a center of mass energy of 7 TeV with an integrated luminosity of 100 pb^{-1}

  
  
  
• Net-baryon number fluctuations in (2+1)-flavor QCD. (arXiv:1007.5164v1 [hep-lat])
  

  We present a lattice study of net-baryon number fluctuations in (2+1)-flavor QCD. The results are based on a Taylor expansion of the pressure with respect to the baryon chemical potential. We calculate higher moments of the net-baryon number fluctuations and compare with the corresponding resonance gas results. We find that for temperature below 0.9T_c the fluctuations seem to agree with the hadron resonance gas predictions. Close to T_c, higher moments are increasingly more sensitive to the critical behavior of the QCD phase transition. Furthermore, we estimate the radius of convergence of the Taylor series as well as the curvature of the transition line in the temperature chemical potential plane.

  
  
  
• The Polyakov loop and correlator of Polyakov loops at next-to-next-to-leading order. (arXiv:1007.5172v1 [hep-ph])
  

  We study the Polyakov loop and the correlator of two Polyakov loops at finite temperature in the weak-coupling regime. We calculate the Polyakov loop at order g^4. The calculation of the correlator of two Polyakov loops is performed at distances shorter than the inverse of the temperature and for electric screening masses larger than the Coulomb potential. In this regime, it is accurate up to order g^6. We also evaluate the Polyakov-loop correlator in an effective field theory framework that takes advantage of the hierarchy of energy scales in the problem and makes explicit the bound-state dynamics. In the effective field theory framework, we show that the Polyakov-loop correlator is at leading order in the multipole expansion the sum of a colour-singlet and a colour-octet quark-antiquark correlator, which are gauge invariant, and compute the corresponding colour-singlet and colour-octet free energies.

  
  
  
• Spin correlations in nonperturbative electron-positron pair creation by petawatt laser pulses colliding with a TeV proton beam. (arXiv:1007.5176v1 [hep-ph])
  

  The influence of the electron spin degree of freedom on nonperturbative electron-positron pair production by high-energy proton impact on an intense laser field of circular polarization is analyzed. Predictions from the Dirac and Klein-Gordon theories are compared and a spin-resolved calculation is performed. We show that the various spin configurations possess very different production probabilities and discuss the transfer of helicity in this highly nonlinear process. Our predictions could be tested by combining the few-TeV proton beam at CERN-LHC with an intense laser pulse from a table-top petawatt laser source.

  
  
  
• Top-spin analysis of new scalar and tensor interactions in e^+ e^- collisions with beam polarization. (arXiv:1007.5183v1 [hep-ph])
  

  We utilize top polarization in the process e^+ e^-\to t\bar{t} at the ILC with transverse beam polarization to probe interactions of the scalar and tensor type beyond the standard model and to disentangle their individual contributions. A powerful model-independent framework for inclusive measurements is employed to describe the spin-momentum correlations. 90% confidence level limits on the interactions with realistic integrated luminosity are presented and are found to improve by an order of magnitude compared to the case when the spin of the top quark is not measured. Sensitivities of the order of a few times 10^{-9} GeV^{-2} for real and imaginary parts of both scalar and tensor couplings at \sqrt{s}=500 and 800 GeV with an integrated luminosity of 500 fb^{-1} and completely polarized beams is shown to be possible.

  
  
  
• Intercepts of the momentum correlation functions in \mu-Bose gas model and their asymptotics. (arXiv:1007.5187v1 [quant-ph])
  

  The so-called \mu-deformed oscillator (or \mu-oscillator) introduced by A.Jannussis, though known for almost two decades, was not yet given sufficient attention. However, some of its unusual properties were demonstrated and it has a potential for application in phenomenology of elementary particles or in quantum optics. In this paper, the corresponding \mu-Bose gas model based on the set of \mu-oscillators is explored. In the framework of this model the intercepts \lambda^(2)(K) and \lambda^(3)(K) of two- and three-particle momentum correlation functions are calculated. To do this, different orders of approximation in the (small) deformation parameter \mu are considered. In our analysis we focus especially on the asymptotic behavior of the obtained intercepts \lambda^(2)(K) and \lambda^(3)(K).

  
  
  
• Role of 2SC pairing in a three-flavor NJL model with axial anomaly. (arXiv:1007.5198v1 [hep-ph])
  

  The phase diagram of strongly interacting matter is studied within a three-flavor Nambu--Jona-Lasinio model, which contains the coupling between chiral and diquark condensates through the axial anomaly. Our results show that it is essential to include the 2SC phase in the analysis. While this is expected for realistic strange quark masses, we find that even for equal up, down, and strange bare quark masses, 2SC pairing can be favored due to spontaneous flavor-symmetry breaking by the axial anomaly. This can lead to a rich phase structure, including BCS- and BEC-like 2SC and CFL phases and new endpoints. On the other hand, the low-temperature critical endpoint, which was found earlier in the same model without 2SC pairing, is almost removed from the phase diagram and cannot be reached from the low-density chirally broken phase without crossing a preceding first-order phase boundary. For physical quark masses no additional critical endpoint is found.

  
  
  
• The QCD Coupling and Parton Distributions at High Precision. (arXiv:1007.5202v1 [hep-ph])
  

  A survey is given on the present status of the nucleon parton distributions and related precision calculations and precision measurements of the strong coupling constant $\alpha_s(M_Z^2)$. We also discuss the impact of these quantities on precision observables at hadron colliders.

  
  
  
• Flavour in supersymmetry: horizontal symmetries or wave function renormalisation. (arXiv:1007.5208v1 [hep-ph])
  

  We compare theoretical and experimental predictions of two main classes of models addressing fermion mass hierarchies and flavour changing neutral currents (FCNC) effects in supersymmetry: Froggatt-Nielsen (FN) U(1) gauged flavour models and Nelson-Strassler/extra dimensional models with hierarchical wave functions for the families. We show that whereas the two lead to identical predictions in the fermion mass matrices, the second class generates a stronger suppression of FCNC effects. We prove that, whereas at first sight the FN setup is more constrained due to anomaly cancelation conditions, imposing unification of gauge couplings in the second setup generates conditions which precisely match the mixed anomaly constraints in the FN setup. Finally, we provide an economical extra dimensional realisation of the hierarchical wave functions scenario in which the leptonic FCNC can be efficiently suppressed due to the strong coupling (CFT) origin of the electron mass.

  
  
  
• Neutrino Mass Sum-rules in Flavor Symmetry Models. (arXiv:1007.5217v1 [hep-ph])
  

  Four different neutrino mass sum-rules have been analyzed: these frequently arise in flavor symmetry models based on the groups A_4, S_4 or T', which are often constructed to generate tri-bimaximal mixing. In general, neutrino mass can be probed in three different ways, using beta decay, neutrino-less double beta decay and cosmology. The general relations between the corresponding three neutrino mass observables are well-known. The sum-rules lead to relations between the observables that are different from the general case and therefore only certain regions in parameter space are allowed. Plots of the neutrino mass observables are given for the sum-rules, and analytical expressions for the observables are provided. The case of deviations from the exact sum-rules is also discussed, which can introduce new features. The sum-rules could be used to distinguish some of the many models in the literature, which all lead to the same neutrino oscillation results.

  
  
  
• Proposal for taking data with the KLOE-2 detector at the DA$\Phi$NE collider upgraded in energy. (arXiv:1007.5219v1 [hep-ex])
  

  This document reviews the physics program of the KLOE-2 detector at DA$\Phi$NE upgraded in energy and provides a simple solution to run the collider above the $\phi$-peak (up to 2, possibly 2.5 GeV). It is shown how a precise measurement of the multihadronic cross section in the energy region up to 2 (possibly 2.5) GeV would have a major impact on the tests of the Standard Model through a precise determination of the anomalous magnetic moment of the muon and the effective fine-structure constant at the $M_Z$ scale. With a luminosity of about $10^{32}$cm$^{-2}$s$^{-1}$, DA$\Phi$NE upgraded in energy can perform a scan in the region from 1 to 2.5 GeV in one year by collecting an integrated luminosity of 20 pb$^{-1}$ (corresponding to a few days of data taking) for single point, assuming an energy step of 25 MeV. A few years of data taking in this region would provide important tests of QCD and effective theories by $\gamma\gamma$ physics with open thresholds for pseudo-scalar (like the $\eta'$), scalar ($f_0,f'_0$, etc...) and axial-vector ($a_1$, etc...) mesons; vector-mesons spectroscopy and baryon form factors; tests of CVC and searches for exotics. In the final part of the document a technical solution for the energy upgrade of DA$\Phi$NE is proposed.

  
  
  
• Top, GigaZ, MegaW. (arXiv:1007.5232v1 [hep-ph])
  

  We review the physics potential of top mass measurements and the GigaZ/MegaW options of the International Linear Collider (ILC) for probing New Physics models and especially the Minimal Supersymmetric Standard Model (MSSM). We demonstrate that the anticipated experimental accuracies at the ILC for the top-quark mass, m_t, the W boson mass, M_W, and the effective leptonic weak mixing angle, sin^2 theta_eff, will provide a high sensitivity to quantum effects of New Physics. In particular, a new and more precise measurement of sin^2 theta_eff, for which the experimental central value is currently obtained from an average where the most precise single measurements differ by more than three standard deviations, could lead to a situation where both the Standard Model and the MSSM in its most general form are ruled out. Alternatively, the precision measurements may resolve virtual effects of SUSY particles even in scenarios where the SUSY particles are so heavy that they escape direct detection at the LHC and the first phase of the ILC.

  
  
  
• Non-minimally coupled f(R) Cosmology. (arXiv:1007.5250v1 [astro-ph.CO])
  

  We investigate the consequences of non-minimal gravitational coupling to matter and study how it differs from the case of minimal coupling by choosing certain simple forms for the nature of coupling, The values of the parameters are specified at $z=0$ (present epoch) and the equations are evolved backwards to calculate the evolution of cosmological parameters. We find that the Hubble parameter evolves more slowly in non-minimal coupling case as compared to the minimal coupling case. In both the cases, the universe accelerates around present time, and enters the decelerating regime in the past. Using the latest Union2 dataset for supernova Type Ia observations as well as the data for baryon acoustic oscillation (BAO) from SDSS observations, we constraint the parameters of Linder exponential model in the two different approaches. We find that there is a upper bound on model parameter in minimal coupling. But for non-minimal coupling case, there is range of allowed values for the model parameter.

  
  
  
• 10 GeV dark matter candidates and cosmic-ray antiprotons. (arXiv:1007.5253v1 [astro-ph.HE])
  

  Recent measurements performed with some direct dark matter detection experiments, e.g. CDMS-II and CoGENT (after DAMA/LIBRA), have unveiled a few events compatible with WIMP-nuclei interactions. The preferred mass range is around 10 GeV, with a quite large spin-independent cross section of $10^{-43}-10^{-41}\,{\rm cm^2}$. In this letter, we recall that a light WIMP with dominant couplings to quarks should also generate cosmic-ray antiprotons. Taking advantage of recent works constraining the Galactic dark matter mass profile on the one hand and on cosmic-ray propagation on the other hand, we point out that considering a thermal annihilation cross section for such low mass candidates unavoidably results in an antiproton flux in tension with the current data, leading either to exclusion or to observable features. This should be taken into account for a consistent interpretation of direct detection signals.

  
  
  
• Direct Production of Lightest Regge Resonances. (arXiv:1007.5254v1 [hep-th])
  

  We discuss direct production of Regge excitations in the collisions of massless four-dimensional superstring states, focusing on the first excited level of open strings ending on D-branes extending into higher dimensions. We construct covariant vertex operators and identify ``universal'' Regge states with the internal parts either trivial or determined by the world-sheet SCFT describing superstrings propagating on an arbitrary Calabi-Yau manifold. We evaluate the amplitudes involving one such massive state and up to three massless ones and express them in the helicity basis. The most important phenomenological applications of our results are in the context of low-mass string (and large extra dimensions) scenarios in which excited string states are expected to be produced at the LHC as soon as the string mass threshold is reached in the center-of-mass energies of the colliding partons. In order to facilitate the use of partonic cross sections, we evaluate them and tabulate for all production processes: gluon fusion, quark absorbing a gluon, quark-antiquark annihilation and quark-quark scattering.

  
  
  
• Modeling the jet quenching, thermal resonance production and hydrodynamical flow in relativistic heavy ion collisions. (arXiv:1007.5272v1 [hep-ph])
  

  The event topology in relativistic heavy ion collisions is determined by various multi-particle production mechanisms. The simultaneous model treatment of different collective nuclear effects at high energies (such as a hard multi-parton fragmentation in hot QCD-matter, thermal resonance production, hydrodynamical flows, etc.) is actual but rather complicated task. We discuss the simulation of the above effects by means of Monte-Carlo model HYDJET++.

  
  
  
• Mass generation and supersymmetry. (arXiv:1007.5275v1 [hep-th])
  

  Using a recent understanding of mass generation for Yang-Mills theory and a quartic massless scalar field theory mapping each other, we show that when such a scalar field theory is coupled to a gauge field and Dirac spinors, all fields become massive at a classical level with all the properties of supersymmetry fulfilled, when the self-interaction of the scalar field is taken infinitely large. Assuming that the mechanism for mass generation must be the same in QCD as in the Standard Model, this implies that Higgs particle must be supersymmetric.

  
  
  
• Chiral corrections to $\pi^-\gamma\to 3\pi$ processes at low energies. (arXiv:1007.5277v1 [hep-ph])
  

  We calculate in chiral perturbation theory the double-pion photoproduction processes $\pi^-\gamma \to \pi^- \pi^0\pi^0$ and $\pi^-\gamma\to \pi^+\pi^-\pi^-$ at low energies. At leading order these reactions are governed by the chiral pion-pion interaction. The next-to-leading order corrections arise from pion-loop diagrams and chiral-invariant counterterms involving the low-energy constants $\bar\ell_1,\, \bar\ell_2,\, \bar\ell_3$ and $\bar\ell_4$. The pertinent production amplitudes $A_1$ and $A_2$ depending on five kinematical variables are given in closed analytical form. We find that the total cross section for neutral pion-pair production $\pi^-\gamma \to\pi^-\pi^0\pi^0$ gets enhanced in the region $\sqrt{s}< 7m_\pi$ by a factor $1.5 - 1.8$ by the next-to-leading order corrections. In contrast to this behavior the total cross section for charged pion-pair production $\pi^-\gamma\to \pi^+ \pi^-\pi^-$ remains almost unchanged in the region $\sqrt{s}< 6m_\pi$ in comparison to its tree-level result. Although the dynamics of the pion-pair production reactions is much richer, this observed pattern can be understood from the different influence of the chiral corrections on the pion-pion final state interaction ($\pi^+\pi^- \to \pi^0\pi^0$ versus $\pi^-\pi^- \to \pi^-\pi^-$). We present also results for the complete set of two-pion invariant mass spectra. The predictions of chiral perturbation theory for the $\pi^-\gamma\to 3\pi$ processes can be tested by the COMPASS experiment which uses Primakoff scattering of high-energy pions in the Coulomb field of a heavy nucleus to extract cross sections for $\pi^-\gamma$ reactions with various final states.

  
  
  
• EDMs vs. CPV in B_{s,d} mixing in two Higgs doublet models with MFV. (arXiv:1007.5291v1 [hep-ph])
  

  We analyze the correlations between electric dipole moments (EDMs) of the neutron and heavy atoms and CP violation in B_{s,d} mixing in two Higgs doublet models respecting the Minimal Flavour Violation hypothesis, with flavour-blind CP-violating (CPV) phases. In particular, we consider the case of flavour-blind CPV phases from i) the Yukawa interactions and ii) the Higgs potential. We show that in both cases the upper bounds on the above EDMs do not forbid sizable non-standard CPV effects in B_s mixing. However, if a large CPV phase in B_s mixing will be confirmed, this will imply EDMs very close to their present experimental bounds, within the reach of the next generation of experiments, as well as BR(B_{s,d}-> mu^+ mu^-) typically largely enhanced over its SM expectation. The two flavour-blind CPV mechanisms can be distinguished through the correlation between S_psi K_S and S_psi phi that is strikingly different if only one of them is relevant. Which of these two CPV mechanisms dominates depends on the precise values of S_psi phi and S_psi K_S, as well as on the CKM phase (as determined by tree-level processes). Current data seems to show a mild preference for a hybrid scenario where both these mechanisms are at work.

  
  
  
• Effective QFT and what it tells us about dynamical torsion. (arXiv:1007.5294v1 [hep-th])
  

  The covariantly constant spacetime torsion is one of the fields which may break Lorentz and CPT symmetry. We review the previous works on the dynamical torsion in the framework of effective quantum field theory (QFT). It turns out that the existence of propagating torsion is strongly restricted by the QFT principles. In particular, the torsion mass must be much greater than the masses of all fermionic particles. In this situation, the main chance to observe torsion is due to some symmetry breaking which may, in principle, produce almost constant background torsion field.

  
  
  
• Parameterizing and Measuring Dark Energy Trajectories from Late-Inflatons. (arXiv:1007.5297v1 [astro-ph.CO])
  

  Bulk dark energy properties are determined by the redshift evolution of its pressure-to-density ratio, $w_{de}(z)$. An experimental goal is to decide if the dark energy is dynamical, as in the quintessence (and phantom) models treated here. We show that a three-parameter approximation $w_{de}(z; \epsilon_s, \epsilon_{\phi\infty}, \zeta_s)$ fits well the ensemble of trajectories for a wide class of late-inflaton potentials $V(\phi)$. Markov Chain Monte Carlo probability calculations are used to confront our $w_{de}(z)$ trajectories with current observational information on Type Ia supernova, Cosmic Microwave Background, galaxy power spectra, weak lensing and the Lyman-${\alpha}$ forest. We find the best constrained parameter is a low redshift slope parameter, $\epsilon_s \propto (\partial \ln V / \partial \phi)^2$ when the dark energy and matter have equal energy densities. A tracking parameter $\epsilon_{\phi\infty}$ defining the high-redshift attractor of $1+w_{de}$ is marginally constrained. Poorly determined is $\zeta_s$, characterizing the evolution of $\epsilon_s$, and a measure of $\partial^2 \ln V / \partial \phi^2$ . The constraints we find already rule out some popular quintessence and phantom models, or restrict their potential parameters. We also forecast how the next generation of cosmological observations improve the constraints: by a factor of about five on $\epsilon_s$ and $\epsilon_{\phi\infty}$, but with $\zeta_s$ remaining unconstrained (unless the true model significantly deviates from $\Lambda$CDM). Thus potential reconstruction beyond an overall height and a gradient is not feasible for the large space of late-inflaton models considered here.

  
  
  
• Frustrated symmetries in multi-Higgs-doublet models. (arXiv:1007.5305v1 [hep-ph])
  

  Within multi-Higgs-doublet models, one can impose symmetries on the Higgs potential, either discrete or continuous, that mix several doublets. In two-Higgs-doublet model any such symmetry can be conserved or spontaneously violated after the electroweak symmetry breaking (EWSB), depending on the coefficients of the potential. With more than two doublets, there exist symmetries which are always spontaneously violated after EWSB. We discuss the origin of this phenomenon and show its similarity to geometric frustration in condensed-matter physics.

  
  
  
• A New Limit for the Non-Commutative Space-Time Parameter. (arXiv:0907.1904v5 [hep-ph] UPDATED)
  

  We study space-time noncommutativity applied to the hydrogen atom and the phenomenological aspects induced. We find that the noncommutative effects are similar to those obtained by considering the extended charged nature of the proton in the atom. To the first order in the noncommutative parameter, it is equivalent to an electron in the fields of a Coulomb potential and an electric dipole and this allows us to get a bound for the parameter. In a second step, we compute noncommutative corrections of the energy levels and find that they are at the second order in the parameter of noncommutativity. By comparing our results to those obtained from experimental spectroscopy, we get another limit for the parameter.

  
  
  
• Intermediate Scale Dependence of Non-Universal Gaugino Masses in Supersymmetric SO(10). (arXiv:0909.2374v3 [hep-ph] UPDATED)
  

  We calculate the dependence on intermediate scale of the gaugino mass ratios upon breaking of SO(10) into the SM via an intermediate group $H$. We see that the ratios change significantly when the intermediate scale is low (say, $10^8$ GeV or 1 Tev) compared to the case when the two breakings occur at the same scale.

  
  
  
• $\Omega^{-}$, $\Xi^{* -}$, $\Sigma^{* -}$ and $\Delta^{-}$ decuplet baryon magnetic moments. (arXiv:0911.4756v4 [hep-ph] UPDATED)
  

  The properties of the ground state $U$-Spin $={3/2}$ baryon decuplet magnetic moments $\Delta^{-}$, $\Xi^{* -}$, $\Sigma^{* -}$ and $\Omega^{-}$ and their ground state spin 1/2 cousins $p$, $n$, $\Lambda$, $\Sigma^{+}$, $\Sigma^{0}$, $\Sigma^{-}$, $\Xi^{+}$, and $\Xi^{-}$ have been studied for many years with a modicum of success. The magnetic moments of many are yet to be determined. Of the decuplet baryons, only the magnetic moment of the $\Omega^{-}$ has been accurately determined. We calculate the magnetic moments of the \emph{physical} decuplet $U$-Spin $={3/2}$ quartet members without ascribing any specific form to their quark structure or intra-quark interactions.

  
  
  
• Diffuse gamma ray constraints on annihilating or decaying Dark Matter after Fermi. (arXiv:0912.0663v2 [astro-ph.CO] UPDATED)
  

  We consider the diffuse gamma ray data from FERMI first year observations and compare them to the gamma ray fluxes predicted by Dark Matter annihilation or decay (both from prompt emission and from Inverse Compton Scattering), for different observation regions of the sky and a range of Dark Matter masses, annihilation/decay channels and Dark Matter galactic profiles. We find that the data exclude large regions of the Dark Matter parameter space not constrained otherwise and discuss possible directions for future improvements. Also, we further constrain Dark Matter interpretations of the e+e- PAMELA/FERMI spectral anomalies, both for the annihilating and the decaying Dark Matter case: under very conservative assumptions, only models producing dominantly mu+mu- and assuming a cored Dark Matter galactic profile can fit the lepton data with masses around 2 TeV.

  
  
  
• Forward-backward asymmetry on Z resonance in SO(5) x U(1) gauge-Higgs unification. (arXiv:0912.1218v2 [hep-ph] UPDATED)
  

  We find that the tree-level predictions of the forward-backward production asymmetries on the Z resonance for b and c quarks, A_FB, in an SO(5) x U(1) gauge-Higgs unification model are markedly close to the central values of the Particle Data Group data unlike the standard model. The decay width of Z boson is evaluated and the S and T parameters are discussed.

  
  
  
• Very-High-Energy Gamma-Ray Signal from Nuclear Photodisintegration as a Probe of Extragalactic Sources of Ultrahigh-Energy Nuclei. (arXiv:1002.3980v2 [astro-ph.HE] UPDATED)
  

  It is crucial to identify the ultrahigh-energy cosmic-ray (UHECR) sources and probe their unknown properties. Recent results from the Pierre Auger Observatory favor a heavy nuclear composition for the UHECRs. Under the requirement that heavy nuclei survive in these sources, using gamma-ray bursts as an example, we predict a diagnostic gamma-ray signal, unique to nuclei - the emission of de-excitation gamma rays following photodisintegration. These gamma rays, boosted from MeV to TeV-PeV energies, may be detectable by gamma-ray telescopes such as VERITAS, HESS, and MAGIC, and especially the next-generation CTA and AGIS. They are a promising messenger to identify and study individual UHE nuclei accelerators.

  
  
  
• Collision geometry fluctuations and triangular flow in heavy-ion collisions. (arXiv:1003.0194v3 [nucl-th] UPDATED)
  

  We introduce the concepts of participant triangularity and triangular flow in heavy-ion collisions, analogous to the definitions of participant eccentricity and elliptic flow. The participant triangularity characterizes the triangular anisotropy of the initial nuclear overlap geometry and arises from event-by-event fluctuations in the participant-nucleon collision points. In studies using a multi-phase transport model (AMPT), a triangular flow signal is observed that is proportional to the participant triangularity and corresponds to a large third Fourier coefficient in two-particle azimuthal correlation functions. Using two-particle azimuthal correlations at large pseudorapidity separations measured by the PHOBOS and STAR experiments, we show that this Fourier component is also present in data. Ratios of the second and third Fourier coefficients in data exhibit similar trends as a function of centrality and transverse momentum as in AMPT calculations. These findings suggest a significant contribution of triangular flow to the ridge and broad away-side features observed in data. Triangular flow provides a new handle on the initial collision geometry and collective expansion dynamics in heavy-ion collisions.

  
  
  
• Distinguishing Dark Matter Stabilization Symmetries Using Multiple Kinematic Edges and Cusps. (arXiv:1003.0899v2 [hep-ph] UPDATED)
  

  We emphasize that the stabilizing symmetry for dark matter (DM) particles does not have to be the commonly used parity (Z_2) symmetry. We therefore examine the potential of the colliders to distinguish models with parity stabilized DM from models in which the DM is stabilized by other symmetries. We often take the latter to be a Z_3 symmetry for illustration. We focus on signatures where a single particle, charged under the DM stabilization symmetry decays into the DM and Standard Model (SM) particles. Such a Z_3-charged "mother" particle can decay into one or two DM particles along with the same SM particles. This can be contrasted with the decay of a Z_2-charged mother particle, where only one DM particle appears. Thus, if the intermediate particles in these decay chains are off-shell, then the reconstructed invariant mass of the SM particles exhibits two kinematic edges for the Z_3 case but only one for the Z_2 case. For the case of on-shell intermediate particles, distinguishing the two symmetries requires more than the kinematic edges. In this case, we note that certain decay chain "topologies" of the mother particle which are present for the Z_3 case (but absent for the Z_2 case) generate a "cusp" in the invariant mass distribution of the SM particles. We demonstrate that this cusp is generally invariant of the various spin configurations. We further apply these techniques within the context of explicit models.

  
  
  
• R-Current DIS on a Shock Wave: Beyond the Eikonal Approximation. (arXiv:1005.0374v2 [hep-ph] UPDATED)
  

  We find the DIS structure functions at strong coupling by calculating R-current correlators on a finite-size shock wave using AdS/CFT correspondence. We improve on the existing results in the literature by going beyond the eikonal approximation for the two lowest orders in graviton exchanges. We argue that since the eikonal approximation at strong coupling resums integer powers of 1/x (with x the Bjorken-x variable), the non-eikonal corrections bringing in positive integer powers of x can not be neglected in the small-x limit, as the non-eikonal order-x correction to the (n+1)st term in the eikonal series is of the same order in x as the nth eikonal term in that series. We demonstrate that, in qualitative agreement with the earlier DIS analysis based on calculation of the expectation value of the Wilson loop in the shock wave background using AdS/CFT, after inclusion of non-eikonal corrections DIS structure functions are described by two momentum scales: Q_1^2 ~ \Lambda^2 \, A^{1/3}/x and Q_2^2 ~ \Lambda^2 \, A^{2/3}, where \Lambda is the typical transverse momentum in the shock wave and A is the atomic number if the shock wave represents a nucleus. We discuss possible physical meanings of the scales Q_1 and Q_2.

  
  
  
• Two-photon and two-gluon decays of p-wave heavy quarkonium using a covariant light-front approach. (arXiv:1005.2811v2 [hep-ph] UPDATED)
  

  In this paper, a study of two-photon and two-gluon decays in the context of p-wave heavy quarkonia is presented. Within the covariant light-front framework, the annihilation rates of scalar and tensor quarkonium states are derived. In the absence of free parameters in this case, the results for the charmonium decay widths are consistent with the experimental data. However, in comparison to other theoretical calculations, there are large discrepancies in our results regarding bottomonia.

  
  
  
• Same-sign trileptons and four-leptons as signatures of new physics at the Large Hadron Collider. (arXiv:1005.3051v2 [hep-ph] UPDATED)
  

  We point out that same-sign multilepton events, not given due attention yet for new physics search, can be extremely useful at the Large Hadron Collider. After showing the easy reducibility of the standard model backgrounds, we demonstrate the viability of same-sign trilepton signals for R-parity breaking supersymmetry, at both 7 and 14 TeV. We find that same-sign four-leptons, too, can have appreciable rates. Same-sign trileptons are also expected, for example, in Little Higgs theories with T-parity broken by anomaly terms.

  
  
  
• An Implication on the Pion Distribution Amplitude from the Pion-Photon Transition Form Factor with the New BABAR Data. (arXiv:1005.3359v2 [hep-ph] UPDATED)
  

  The new BABAR data on the pion-photon transition form factor arouses people's new interests on the determination of pion distribution amplitude. To explain the data, we take both the leading valence quark state's and the non-valence quark states' contributions into consideration, where the valence quark part up to next-to-leading order is presented and the non-valence quark part is estimated by a phenomenological model based on its limiting behavior at both $Q^2\to 0$ and $Q^2\to\infty$. Our results show that to be consistent with the new BABAR data at large $Q^2$ region, a broader other than the asymptotic-like pion distribution amplitude should be adopted. The broadness of the pion distribution amplitude is controlled by a parameter $B$. It has been found that the new BABAR data at low and high energy regions can be explained simultaneously by setting $B$ to be around 0.60, in which the pion distribution amplitude is closed to the Chernyak-Zhitnitsky form.

  
  
  
• XENON10/100 dark matter constraints in comparison with CoGeNT and DAMA: examining the Leff dependence. (arXiv:1006.0972v2 [astro-ph.CO] UPDATED)
  

  We consider the compatibility of DAMA/LIBRA, CoGeNT, XENON10 and XENON100 results for spin-independent (SI) dark matter Weakly Interacting Massive Particles (WIMPs), particularly at low masses (~ 10 GeV), assuming a standard dark matter halo. The XENON bounds depend on the scintillation efficiency factor Leff for which there is considerable uncertainty. Thus we consider various extrapolations for Leff at low energy. With the Leff measurements we consider, XENON100 results are found to be insensitive to the low energy extrapolation. We find the strongest bounds are from XENON10, rather than XENON100, due to the lower energy threshold. For reasonable choices of Leff and for the case of SI elastic scattering, XENON10 is incompatible with the DAMA/LIBRA 3$\sigma$ region and severely constrains the 7-12 GeV WIMP mass region of interest published by the CoGeNT collaboration.

  
  
  
• Implications of large dimuon CP asymmetry in B_{d,s} decays on minimal flavor violation with low tan beta. (arXiv:1007.1872v2 [hep-ph] UPDATED)
  

  The D0 collaboration has recently announced evidence for a dimuon CP asymmetry in B_{d,s} decays of order one percent. If confirmed, this asymmetry requires new physics. We argue that for minimally flavor violating (MFV) new physics, and at low tan beta=v_u/v_d, there are only two four-quark operators (Q_{2,3}) that can provide the required CP violating effect. The scale of such new physics must lie below 260 GeV sqrt{tan beta}. The effect is universal in the B_s and B_d systems, leading to S_{psi K}~sin(2beta)-0.15 and S_{psi phi}~0.25. The effects on epsilon_K and on electric dipole moments are negligible. The most plausible mechanism is tree-level scalar exchange. MFV supersymmetry with low tan beta will be excluded. Finally, we explain how a pattern of deviations from the Standard Model predictions for S_{psi phi}, S_{psi K} and epsilon_K can be used to test MFV and, if MFV holds, to probe its structure in detail.

  
  
  
• Magnetic Inelastic Dark Matter. (arXiv:1007.4200v2 [hep-ph] UPDATED)
  

  Iodine is distinguished from other elements used in dark matter direct detection experiments both by its large mass as well as its large magnetic moment. Inelastic dark matter utilizes the large mass of iodine to allay tensions between the DAMA annual modulation signature and the null results from other experiments. We explore models of inelastic dark matter that also take advantage of the second distinct property of iodine, namely its large magnetic moment. In such models the couplings are augmented by magnetic, rather than merely electric, interactions. These models provide simple examples where the DAMA signal is compatible with all existing limits. We consider dipole moments for the WIMP, through conventional magnetism as well as ``dark'' magnetism, including both magnetic-magnetic and magnetic-electric scattering. We find XENON100 and CRESST should generically see a signal, although suppressed compared with electric inelastic dark matter models, while KIMS should see a modulated signal comparable to or larger than that of DAMA. In a large portion of parameter space, de-excitation occurs promptly, producing a ~ 100 keV photon inside large xenon experiments alongside the nuclear recoil. This effect could be searched for, but if not properly considered may cause nuclear recoil events to fail standard cuts.

  
  
  
• Glueball spectrum and hadronic processes in low-energy QCD. (arXiv:1007.4479v2 [hep-ph] UPDATED)
  

  Low-energy limit of quantum chromodynamics (QCD) is obtained using a mapping theorem recently proved. This theorem states that, classically, solutions of a massless quartic scalar field theory are approximate solutions of Yang-Mills equations in the limit of the gauge coupling going to infinity. Low-energy QCD is described by a Yukawa theory further reducible to a Nambu-Jona-Lasinio model. At the leading order one can compute glue-quark interactions and one is able to calculate the properties of the $\sigma$ and $\eta-\eta'$ mesons. Finally, it is seen that all the physics of strong interactions, both in the infrared and ultraviolet limit, is described by a single constant $\Lambda$ arising in the ultraviolet by dimensional transmutation and in the infrared as an integration constant.

  
  
  
• Recent results and perspectives on cosmic rays ground experiments. (arXiv:1007.4710v2 [astro-ph.HE] UPDATED)
  

  I summarize in this paper the results and perspectives of representative ground experiments for the observation of very high energy cosmic rays.

  
  
  
• Superluminal problem in diffusion of relativistic particles and its phenomenological solution. (arXiv:0805.1867v4 [astro-ph] CROSS LISTED)
  

  We discuss the superluminal problem in the diffusion of ultra high energy protons with energy losses taken into account. The phenomenological solution of this problem is found with help of the generalized J\"uttner propagator, originally proposed for relativization of the Maxwellian gas distribution. It is demonstrated that the generalized J\"uttner propagator gives the correct expressions in the limits of diffusive and rectilinear propagation of the charged particles in the magnetic fields, together with the intermediate regime, in all cases without superluminal velocities. This solution, very general for the diffusion, is considered for two particular cases: diffusion inside the stationary objects, like e.g. galaxies, clusters of galaxies etc, and for expanding universe. The comparison with the previously obtained solutions for propagation of UHE protons in magnetic fields is performed.

  
  
  
• Exact solution of Dyson-Schwinger equations for a scalar field theory. (arXiv:0909.2428v2 [hep-th] CROSS LISTED)
  

  We exactly solve Dyson-Schwinger equations for a massless quartic scalar field theory. n-point functions are computed till n=4 and the exact propagator computed from the two-point function. The spectrum is so obtained, being the same of a harmonic oscillator. Callan-Symanzik equation for the two-point function gives the beta function. This gives the result that this theory has only trivial fixed points. In the low-energy limit the coupling goes to zero making the theory trivial and, at high energies, it reaches infinity. No Landau pole appears, rather this should be seen as a precursor, in a weak perturbation expansion, of the coupling reaching the trivial fixed point at infinity. Using a mapping theorem, recently proved, between massless quartic scalar field theory and gauge theories, we derive some properties of the latter.

  
  
  
• Stability of Holographic Superconductors. (arXiv:1007.5002v1 [hep-th] CROSS LISTED)
  

  We study the dynamical stability of holographic superconductors. We first classify perturbations around black hole background solutions into vector and scalar sectors by means of a 2-dimensional rotational symmetry. We prove the stability of the vector sector by explicitly constructing the positive definite Hamiltonian. To reveal a mechanism for the stabilization of a superconducting phase, we construct a quadratic action for the scalar sector. From the action, we see the stability of black holes near a critical point is determined by the equation of motion for a charged scalar field. We show the effective mass of the charged scalar field in hairy black holes is always above the Breitenlohner-Freedman bound near the critical point due to the backreaction of a gauge field. It implies the stability of the superconducting phase. We also argue that the stability continues away from the critical point.