WebGrazer Summary

Thu Nov 19 18:25:21 PST 2009


hep-ph

[1]  arXiv:0911.3655 [ps, pdf, other]
Title:NNLO vertex corrections to non-leptonic B decays: Tree amplitudes
Authors: M. Beneke, T. Huber, Xin-Qiang Li (RWTH Aachen University)
Comments: 52 pages, 8 figures, 3 tables. Equations (42) and (84) are contained in electronic form in the source file of the present submission
Subjects: High Energy Physics - Phenomenology (hep-ph)

The colour-suppressed tree amplitude in non-leptonic B decays is particularly sensitive to perturbative and non-perturbative corrections. We calculate the two-loop (NNLO) vertex corrections to the colour-suppressed and colour-allowed tree amplitudes in QCD factorization. Our results are given completely analytically, including the full dependence on the charm quark mass. We then update theoretical predictions for a range of interesting observables derived from pi pi, pi rho, and rho rho final states that do not depend (significantly) on penguin contributions, and hence are now available with NNLO accuracy. We observe good agreement with experimental data within experimental and theoretical errors, except for observables involving the pi^0 pi^0 branching fraction.

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[2]  arXiv:0911.3656 [pdf, other]
Title:New Physics Signals in Longitudinal Gauge Boson Scattering at the LHC
Subjects: High Energy Physics - Phenomenology (hep-ph)

We introduce a novel technique designed to look for signatures of new physics in vector boson fusion processes at the TeV scale. This functions by measuring the polarization of the vector bosons to determine the relative longitudinal to transverse production. In studying this ratio we can directly probe the high energy E^2-growth of longitudinal vector boson scattering amplitudes characteristic of models with non-Standard Model (SM) interactions. We will focus on studying models parameterized by an effective Lagrangian that include a light Higgs with non-SM couplings arising from TeV scale new physics associated with the electroweak symmetry breaking, although our technique can be used in more general scenarios. We will show that this technique is stable against the large uncertainties that can result from variations in the factorization scale, improving upon previous studies that measure cross section alone.

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[5]  arXiv:0911.3694 [ps, pdf, other]
Title:X(3915) and X(4350) as new members in P-wave charmonium family
Comments: 4 pages, 4 figures, 3 tables
Subjects: High Energy Physics - Phenomenology (hep-ph)

The analysis of the mass spectrum and the calculation of the strong decay of P-wave charmonium states strongly support to explain the newly observed X(3915) and X(4350) as new members in P-wave charmonium family, i.e., $\chi_{c0}^\prime$ for X(3915) and $\chi_{c2}^{\prime\prime}$ for X(4350). Under the P-wave charmonium assignment to X(3915) and X(4350), the $J^{PC}$ quantum numbers of X(3915) and X(4350) must be $0^{++}$ and $2^{++}$ respectively, which provide the important criterion to test P-wave charmonium explanation for X(3915) and X(4350) proposed by this letter. The decay behavior of the remaining two P-wave charmonium states with the second radial excitation is predicted, and experimental search for them is suggested.

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[6]  arXiv:0911.3711 [ps, pdf, other]
Title:Radiative and flavor-violating transitions of leptons from interactions with color-octet particles
Authors: Yi Liao (1, 2 and 3), Ji-Yuan Liu (2) ((1) Chep, Peking U., (2) Nankai U., (3) Kitpc, Cas)
Comments: 20 pages, 7 figures
Subjects: High Energy Physics - Phenomenology (hep-ph)

It has been recently proposed that neutrino mass could originate from Yukawa interactions of leptons with new colored particles. This raises the interesting possibility of testing mass generation through copious production of those particles at hadron colliders. A realistic assessment of it however should take into account how large those interactions could be from available precision results. In this work we make a systematic analysis to the flavor structure in Yukawa couplings, provide a convenient parametrization to it, and investigate the rare radiative and pure leptonic decays of the muon and tau leptons. For general values of parameters the muon decays set stringent constraints on the couplings, and all rare tau decays are far below the current experimental sensitivity. However, there is room in parameter space in which the muon decays could be significantly suppressed by destructive interference between colored particles without generically reducing the couplings themselves. This is also the region of parameters that is relevant to collider physics. We show that for this part of parameter space some tau decays can reach or are close to the current level of precision.

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[9]  arXiv:0911.3730 [pdf, other]
Title:Supersymmetric Inflation with the Ordinary Higgs?
Authors: K. Tamvakis
Comments: 7 pages, 1 figure
Subjects: High Energy Physics - Phenomenology (hep-ph)

We consider a model of D-term inflation in which the inflaton coincides with the standard Higgs doublet. Non-renormalizable terms are controlled by a discrete R-symmetry of the superpotential. We consider radiative corrections to the scalar potential and find that Higgs inflation in the slow-roll approximation is viable and consistent with CMB data, although with a rather large value of the non-renormalizable coupling involved.

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[10]  arXiv:0911.3761 [ps, pdf, other]
Title:Bulk Higgs field in a Randall-Sundrum model with nonvanishing brane cosmological constant
Comments: 7 pages, 2 tables
Subjects: High Energy Physics - Phenomenology (hep-ph)

We consider the possibility of Higgs mechanism in the bulk in a generalised Randall-Sundrum model, where a nonvanishing cosmological constant is induced on the visible brane. This scenario has the advantage of accommodating positive tension of the visible brane and thus ensures stability of the model. It is shown that several problems usually associated with this mechanism are avoided if some dimensionful parameters in the bulk are allowed to lie a little below the Planck mass. The most important of these is keeping the lowest massive mode in the scale of the standard electroweak model, and at the same time reducing the gauge coupling of the next excited state, thus ameliorating otherwise stringent phenomenological constraints.

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[11]  arXiv:0911.3776 [ps, pdf, other]
Title:The multi-channel low energy neutrino factory
Comments: 13 pages, 9 eps figures
Subjects: High Energy Physics - Phenomenology (hep-ph)

We show that a low energy neutrino factory with a baseline of 1300 km, muon energy of 4.5 GeV, and either a 20 kton totally active scintillating detector or 100 kton liquid argon detector, can have outstanding sensitivity to the neutrino oscillation parameters theta13, delta and the mass hierarchy. For our estimated exposure of 2.8 x 10^{23} kton x decays per muon polarity, the low energy neutrino factory has sensitivity to theta13 and delta for sin^2(2theta13) > 10^{-4} and to the mass hierarchy for sin^2(2theta13) > 10^{-3}.

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[12]  arXiv:0911.3795 [ps, pdf, other]
Title:Potentially Large One-loop Corrections to WIMP Annihilation
Comments: 19 pages, 6 figures
Subjects: High Energy Physics - Phenomenology (hep-ph)

We compute one--loop corrections to the annihilation of non--relativistic particles $\chi$ due to the exchange of a (gauge or Higgs) boson $\varphi$ with mass $\mu$ in the initial state. In the limit $m_\chi \gg \mu$ this leads to the "Sommerfeld enhancement" of the annihilation cross section. However, here we are interested in the case $\mu \lsim m_\chi$, where the one--loop corrections are well--behaved, but can still be sizable. We find simple and accurate expressions for annihilation from both $S-$ and $P-$wave initial states; they differ from each other if $\mu \neq 0$. In order to apply our results to the calculation of the relic density of Weakly Interacting Massive Particles (WIMPs), we describe how to compute the thermal average of the corrected cross sections. We show that these corrections can decrease the relic density of neutralinos in the Minimal Supersymmetric extension of the Standard Model by more than 1%, if the lightest neutralino is a strongly mixed state.

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[13]  arXiv:0911.3811 [ps, pdf, other]
Title:Correlated enhancements in $D_s \to \ell\nu$, $(g-2)$ of muon, and lepton flavor violating $\tau$ decays with two R-parity violating couplings
Comments: 11 pages, 8 figures
Subjects: High Energy Physics - Phenomenology (hep-ph)

With just two R-parity violating couplings, $\lambda'_{223}$ and $\lambda'_{323}$, we correlate several channels, namely, $D_s \to \ell \nu$ ($\ell = \mu, \tau$), $(g-2)_\mu$, and some lepton flavor violating $\tau$ decays. For $\lambda'_{223} = \lambda'_{323} \sim 0.3$ and for a common superpartner mass of 300 GeV, which explain the recently observed excesses in the above $D_s$ decay channels, we predict the following R-parity violating contributions: ${\rm Br} (\tau \to \mu \gamma) \sim 4.5 \cdot 10^{-8}$, ${\rm Br} (\tau \to \mu\mu\mu) \sim 1.2 \cdot 10^{-8}$, ${\rm Br} (\tau \to \mu\eta/\eta') \sim 4 \cdot 10^{-10}$, and $(g_\mu-2)/2 \sim 4 \cdot 10^{-11}$. We exhibit our results through observable versus observable correlation plots.

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[15]  arXiv:0911.3848 [ps, pdf, other]
Title:Meson properties at finite temperature in a three flavor nonlocal chiral quark model with Polyakov loop
Comments: 20 pages, 4 figs
Subjects: High Energy Physics - Phenomenology (hep-ph)

We study the finite temperature behavior of light scalar and pseudoscalar meson properties in the context of a three-flavor nonlocal chiral quark model. The model includes mixing with active strangeness degrees of freedom, and takes care of the effect of gauge interactions by coupling the quarks with the Polyakov loop. We analyze the chiral restoration and deconfinement transitions, as well as the temperature dependence of meson masses, mixing angles and decay constants. The critical temperature is found to be $T_c \simeq 202$ MeV, in better agreement with lattice results than the value recently obtained in the local SU(3) PNJL model. It is seen that above $T_c$ pseudoscalar meson masses get increased, becoming degenerate with the masses of their chiral partners. The temperatures at which this matching occurs depend on the strange quark composition of the corresponding mesons. The topological susceptibility shows a sharp decrease after the chiral transition, signalling the vanishing of the U(1)$_A$ anomaly for large temperatures.

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[17]  arXiv:0911.3874 [pdf, other]
Title:Lepton Flavour Violation in a Supersymmetric Model with A4 Flavour Symmetry
Comments: 44 pages
Subjects: High Energy Physics - Phenomenology (hep-ph)

We compute the branching ratios for mu-> e gamma, tau-> mu gamma and tau -> e gamma in a supersymmetric model invariant under the flavour symmetry group A4 X Z3 X U(1)_{FN}, in which near tri-bimaximal lepton mixing is naturally predicted. At leading order in the small symmetry breaking parameter u, which is of the same order as the reactor mixing angle theta_{13}, we find that the branching ratios generically scale as u^2. Applying the current bound on the branching ratio of mu -> e gamma shows that small values of u or tan(beta) are preferred in the model for mass parameters m_{SUSY} and m_{1/2} smaller than 1000 GeV. The bound expected from the on-going MEG experiment will provide a severe constraint on the parameter space of the model either enforcing u approx 0.01 and small tan(beta) or m_{SUSY} and m_{1/2} above 1000 GeV. In the special case of universal soft supersymmetry breaking terms in the flavon sector a cancellation takes place in the amplitudes and the branching ratios scale as u^4, allowing for smaller slepton masses. The branching ratios for tau -> mu gamma and tau -> e gamma are predicted to be of the same order as the one for mu -> e gamma, which precludes the possibility of observing these tau decays in the near future.

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[18]  arXiv:0911.3890 [ps, pdf, other]
Title:Renormalization Group Fixed Point with a Fourth Generation: Higgs-induced Bound States and Condensates
Authors: P. Q. Hung, Chi Xiong
Comments: 18 pages, 9 figures
Subjects: High Energy Physics - Phenomenology (hep-ph)

In the Standard Model with four generations, the two-loop renormalization group equations for the Higgs quartic and Yukawa couplings have a fixed point structure. If the masses of the fourth family are sufficiently heavy, it will contain a natural scale $\Lambda_{FP}$ in the range of a few TeV to the order of $10^2$ TeV, above which the Higgs quartic and Yukawa couplings become practically constant. We found that around $\Lambda_{FP}$ the strong Yukawa couplings make it possible for the fourth generation to form bound states, including composite extra Higgs doublets. In this scenario the fourth generation condensates are obtained without introducing Technicolor or other unknown interactions.

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[19]  arXiv:0911.3892 [ps, pdf, other]
Title:Renormalization Group Fixed Point with a Fourth Generation: Solution to the hierarchy problem
Authors: P. Q. Hung, Chi Xiong
Comments: 4 pages, 3 figures
Subjects: High Energy Physics - Phenomenology (hep-ph)

It has been shown in an accompanying paper that the Higgs quartic and Yukawa sectors of the Standard Model (SM) with four generations exhibit at a two-loop level a fixed point structure which gives rise to bound states and Higgs-like condensates made up of the 4th generation quarks and leptons. The latter phenomenon occurs around the scale $\Lambda_{FP}$ where the fixed point is located. Depending on the initial values, near the electroweak scale, of the fourth generation Yukawa couplings, $\Lambda_{FP}$ can range from a TeV to very high energies. We propose a solution to the hierarchy problem based on a possible existence of a fixed point at a scale $\Lambda_{FP} \sim O(\textrm{TeV})$ coming from a heavy fourth generation.

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[22]  arXiv:hep-ph/0512168 (replaced) [ps, pdf, other]
Title:A Numerical Analysis of the Supersymmetric Flavor Problem and Radiative Fermion Masses
Comments: 12 pages, 10 figures
Journal-ref: Rev. Mex. Fis. 55 (4) (2009) 270-281
Subjects: High Energy Physics - Phenomenology (hep-ph)
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[23]  arXiv:0902.1512 (replaced) [ps, pdf, other]
Title:Invisible Higgs Decays from Higgs Graviscalar Mixing
Authors: Daniele Dominici (University of Florence), John F. Gunion (U.C. Davis)
Comments: 16 pages, 7 figures, minor improvements included
Subjects: High Energy Physics - Phenomenology (hep-ph)
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[26]  arXiv:0905.2517 (replaced) [ps, pdf, other]
Title:The GENIE Neutrino Monte Carlo Generator
Comments: 36 pages, 6 figures, submitted to Nucl.Instrum.Meth.A
Subjects: High Energy Physics - Phenomenology (hep-ph)
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[33]  arXiv:0911.2460 (replaced) [ps, pdf, other]
Title:Direct production of a light CP-odd Higgs boson at the Tevatron and LHC
Comments: 23 pages, 12 figures, minor additions
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
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[34]  arXiv:0911.3595 (replaced) [ps, pdf, other]
Title:Screened perturbation theory for 3d Yang-Mills theory and the magnetic modes of hot QCD
Comments: 10 p.,Latex error fixed, Invited talk at International Workshop on QCD Green's Functions, Confinement and Phenomenology (QCD-TNT09), Trento, Italy, 7-11 September
Subjects: High Energy Physics - Phenomenology (hep-ph)
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hep-th

[11]  arXiv:0911.3806 [ps, pdf, other]
Title:Stability of Asymptotically Schroedinger RN Black Hole and Superconductivity
Comments: 18 pages, 6 figures
Subjects: High Energy Physics - Theory (hep-th)

We perform a perturbative (near-critical) analysis of the stability of an asymptotically Schroedinger Reissner-Nordstrom black hole with respect to generation of charged scalar hair. We find that apart from the expected instability at low temperatures typical of holographic models of superconductivity, in the presence of certain operators a similar instability appears as well at high temperatures. We propose that the reason for such a phase diagram could be due to peculiar features of the dual gauge theory or the failure of the model to provide a consistent holographic dual of a non-relativistic superconductor.

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[13]  arXiv:0911.3891 [pdf, other]
Title:The phase portrait of a matter bounce in Horava-Lifshitz cosmology
Authors: Ewa Czuchry
Comments: 14 pages, 6 figures
Subjects: High Energy Physics - Theory (hep-th)

The occurrence of a bounce in FRW cosmology requires modifications of general relativity. An example of such a modification is the recently proposed Horava-Lifshitz theory of gravity, which includes a ``dark radiation'' term with a negative coefficient in the analog of the Friedmann equation. This paper describes a phase space analysis of models of this sort with the aim of determining to what extent bouncing solutions can occur. A simplification, valid in the relevant region, allows a reduction of the dimension of phase space so that visualization in three dimensions is possible. It is found that a bounce is possible, but not generic in models under consideration. Apart from previously known bouncing solutions some new ones are also described. Other interesting solutions found include ones which describe a novel sort of stationary universes.

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[15]  arXiv:0911.3396 (cross-list from astro-ph.CO) [ps, pdf, other]
Title:Universal properties of Dark Matter halos
Comments: 4 pages, 1 figure, revtex
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO); Galaxy Astrophysics (astro-ph.GA); High Energy Physics - Theory (hep-th)

We discuss the universal relation between density and size of Dark Matter halos.This relation was recently shown to hold on a wide range of scales, from dwarf galaxies to galaxy clusters, both in astronomical observations and numerical simulations of structure formation in the Universe. The nature of this relation has not been previously understood. We demonstrate that this relation can be derived analytically in a "secondary infall" model of structure formation. Qualitative understanding given by this model provides a new tool to observationally constrain the properties of DM and large scale modifications of gravity.

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[16]  arXiv:0911.3428 (cross-list from gr-qc) [ps, pdf, other]
Title:On the Relation between Operator Constraint --, Master Constraint --, Reduced Phase Space --, and Path Integral Quantisation
Comments: 43 pages
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

Path integral formulations for gauge theories must start from the canonical formulation in order to obtain the correct measure. A possible avenue to derive it is to start from the reduced phase space formulation. In this article we review this rather involved procedure in full generality. Moreover, we demonstrate that the reduced phase space path integral formulation formally agrees with the Dirac's operator constraint quantisation and, more specifically, with the Master constraint quantisation for first class constraints. For first class constraints with non trivial structure functions the equivalence can only be established by passing to Abelian(ised) constraints which is always possible locally in phase space. Generically, the correct configuration space path integral measure deviates from the exponential of the Lagrangian action. The corrections are especially severe if the theory suffers from second class secondary constraints. In a companion paper we compute these corrections for the Holst and Plebanski formulations of GR on which current spin foam models are based.

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[17]  arXiv:0911.3431 (cross-list from gr-qc) [ps, pdf, other]
Title:On the Relation between Rigging Inner Product and Master Constraint Direct Integral Decomposition
Comments: 25 pages
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th); Mathematical Physics (math-ph)

Canonical quantisation of constrained systems with first class constraints via Dirac's operator constraint method proceeds by the thory of Rigged Hilbert spaces, sometimes also called Refined Algebraic Quantisation (RAQ). This method can work when the constraints form a Lie algebra. When the constraints only close with nontrivial structure functions, the Rigging map can no longer be defined.
To overcome this obstacle, the Master Constraint Method has been proposed which replaces the individual constraints by a weighted sum of absolute squares of the constraints. Now the direct integral decomposition methods (DID), which are closely related to Rigged Hilbert spaces, become available and have been successfully tested in various situations.
It is relatively straightforward to relate the Rigging Inner Product to the path integral that one obtains via reduced phase space methods. However, for the Master Constraint this is not at all obvious. In this paper we find sufficient conditions under which such a relation can be established. Key to our analysis is the possibility to pass to equivalent, Abelian constraints, at least locally in phase space. Then the Master Constraint DID for those Abelian constraints can be directly related to the Rigging Map and therefore has a path integral formulation.

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[18]  arXiv:0911.3432 (cross-list from gr-qc) [ps, pdf, other]
Title:Path-integral for the Master Constraint of Loop Quantum Gravity
Authors: Muxin Han
Comments: 19 pages
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

In the present paper, we start from the canonical theory of loop quantum gravity and the master constraint programme. The physical inner product is expressed by using the group averaging technique for a single self-adjoint master constraint operator. By the standard technique of skeletonization and the coherent state path-integral, we derive a path-integral formula from the group averaging for the master constraint operator. Our derivation in the present paper suggests there exists a direct link connecting the canonical Loop quantum gravity with a path-integral quantization or a spin-foam model of General Relativity.

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[19]  arXiv:0911.3433 (cross-list from gr-qc) [ps, pdf, other]
Title:Canonical path integral measures for Holst and Plebanski gravity. I. Reduced Phase Space Derivation
Comments: 26 pages
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

An important aspect in defining a path integral quantum theory is the determination of the correct measure. For interacting theories and theories with constraints, this is non-trivial, and is normally not the heuristic "Lebesgue measure" usually used. There have been many determinations of a measure for gravity in the literature, but none for the Palatini or Holst formulations of gravity. Furthermore, the relations between different resulting measures for different formulations of gravity are usually not discussed.
In this paper we use the reduced phase technique in order to derive the path-integral measure for the Palatini and Holst formulation of gravity, which is different from the Lebesgue measure up to local measure factors which depend on the spacetime volume element and spatial volume element.
From this path integral for the Holst formulation of GR we can also give a new derivation of the Plebanski path integral and discover a discrepancy with the result due to Buffenoir, Henneaux, Noui and Roche (BHNR) whose origin we resolve. This paper is the first in a series that aims at better understanding the relation between canonical LQG and the spin foam approach.

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[20]  arXiv:0911.3436 (cross-list from gr-qc) [ps, pdf, other]
Title:Canonical Path-Integral Measures for Holst and Plebanski Gravity. II. Gauge Invariance and Physical Inner Product
Authors: Muxin Han
Comments: 34 pages
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

This article serves as a continuation for the discussion in arXiv:0911.3433, we analyze the invariance properties of the gravity path-integral measure derived from canonical framework, and discuss which path-integral formula may be employed in the concrete computation e.g. constructing a spin-foam model, so that the final model can be interpreted as a physical inner product in the canonical theory.

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[23]  arXiv:0911.3597 (cross-list from quant-ph) [ps, pdf, other]
Title:Negative Energy Densities in Quantum Field Theory
Authors: L.H. Ford
Comments: 10 pages, 2 figures. Contribution to proceedings of Quantum Field Theory under the Influence of External Conditions (QFEXT09), Norman, Oklahoma, September 2009
Subjects: Quantum Physics (quant-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

Quantum field theory allows for the suppression of vacuum fluctuations, leading to sub-vacuum phenomena. One of these is the appearance of local negative energy density. Selected aspects of negative energy will be reviewed, including the quantum inequalities which limit its magnitude and duration. However, these inequalities allow the possibility that negative energy and related effects might be observable. Some recent proposals for experiments to search for sub-vacuum phenomena will be discussed. Fluctuations of the energy density around its mean value will also be considered, and some recent results on a probability distribution for the energy density in two dimensional spacetime are summarized.

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[27]  arXiv:0706.3050 (replaced) [ps, pdf, other]
Title:Cold dark matter from "strong gravity"
Authors: T. R. Mongan
Comments: Shortened, with added remarks on the relation of the dark matter candidate to a minimum mass for black holes, DAMA/LIBRA results and dark matter production at accelerators
Subjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics (astro-ph); High Energy Physics - Theory (hep-th)
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[34]  arXiv:0907.1434 (replaced) [ps, pdf, other]
Title:Holographic dual of Cold Trapped Fermions
Comments: 22 page latex, v2:reference added, sec.7's title change. v3) c_V recalculated, v4)C_V T in all dimension is stressed v5) a version to be accepted in jhep
Subjects: High Energy Physics - Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el)
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[35]  arXiv:0908.2757 (replaced) [ps, pdf, other]
Title:Tunneling and propagation of vacuum bubbles on dynamical backgrounds
Comments: 29 pages, 8 figures, typos corrected, matches published version
Journal-ref: JCAP 0911:008,2009
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
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[36]  arXiv:0908.3487 (replaced) [ps, pdf, other]
Title:The Three Dimensional Dual of 4D Chirality
Comments: 10 pages, small misprints corrected, reference [16] updated. Version to appear in JHEP
Subjects: High Energy Physics - Theory (hep-th)
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[39]  arXiv:0909.5251 (replaced) [ps, pdf, other]
Title:Entropy Perturbations in N-flation
Comments: References added, some typos corrected and figures adjusted. Accepted by Phys. Rev. D
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
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astro-ph cosmology

[5]  arXiv:0911.3666 [ps, pdf, other]
Title:Revealing an Energetic Galaxy-Wide Outflow in a z~2 Ultraluminous Infrared Galaxy
Comments: 6 pages, 3 figures, to appear in Proceedings of "Accretion and Ejection in AGN: A Global View", Lake Como, Italy, June 22-26, 2009, ASP conference series. Based on arXiv:0911.0014 which is now MNRAS, in press
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO)

Leading models of galaxy formation require large-scale energetic outflows to regulate the growth of distant galaxies and their central black holes. However, current observational support for this hypothesis at high redshift is mostly limited to rare z>2 radio galaxies. Here we present Gemini-North NIFS Intregral Field Unit (IFU) observations of the [O III]5007 emission from a z~2 ultraluminous infrared galaxy (ULIRG; L_IR>10^12 L_sol) with an optically identified Active Galactic Nucleus (AGN). The spatial extent (~4-8 kpc) of the high velocity and broad [O III] emission are consistent with that found in z>2 radio galaxies, indicating the presence of a large-scale energetic outflow in a galaxy population potentially orders of magnitude more common than distant radio galaxies. The low radio luminosity of this system indicates that radio-bright jets are unlikely to be responsible for driving the outflow. However, the estimated energy input required to produce the large-scale outflow signatures (of order ~10^59 ergs over ~30 Myrs) could be delivered by a wind radiatively driven by the AGN and/or supernovae winds from intense star formation. The energy injection required to drive the outflow is comparable to the estimated binding energy of the galaxy spheroid, suggesting that it can have a significant impact on the evolution of the galaxy. We argue that the outflow observed in this system is likely to be comparatively typical of the high-redshift ULIRG population and discuss the implications of these observations for galaxy formation models.

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[7]  arXiv:0911.3709 [ps, pdf, other]
Title:Simulating X-ray Supercavities and Their Impact on Galaxy Clusters
Authors: Fulai Guo, William G. Mathews (UC Santa Cruz)
Comments: Submitted to ApJ. 11 pages, 6 figures
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)

Recent X-ray observations of hot gas in the galaxy cluster MS 0735.6+7421 reveal huge radio-bright, quasi-bipolar X-ray cavities having a total energy ~10^{62} ergs, the most energetic AGN outburst currently known. We investigate the evolution of this outburst with two-dimensional axisymmetric gasdynamical calculations in which the cavities are inflated by relativistic cosmic rays. Many key observational features of the cavities and associated shocks are successfully reproduced. The radial elongation of the cavities indicates that cosmic rays were injected into the cluster gas by a (jet) source moving out from the central AGN. AGN jets of this magnitude must be almost perfectly identically bipolar. The relativistic momentum of a single jet would cause a central AGN black hole of mass 10^9 M_{sun} to recoil at ~6000 km s^{-1}, exceeding kick velocities during black hole mergers, and be ejected from the cluster-center galaxy. When the cavity inflation is complete, 4PV underestimates the total energy received by the cluster gas. Deviations of the cluster gas from hydrostatic equilibrium are most pronounced during the early cavity evolution when the integrated cluster mass found from the observed gas pressure gradient can have systematic errors near the cavities of ~10-30%. The creation of the cavity with cosmic rays generates a long-lasting global cluster expansion that reduces the total gas thermal energy below that received from the cavity shock. One Gyr after this single outburst, a gas mass of ~ 6 \times 10^{11} M_{sun} is transported out beyond a cluster radius of 500 kpc. Such post-cavity outflows can naturally produce the discrepancy observed between the cluster gas mass fraction and the universal baryon fraction inferred from WMAP observations. (Abridged)

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astro-ph high energy

[2]  arXiv:0911.3774 [pdf, other]
Title:Characteristic velocities of stripped-envelope core-collapse supernova cores
Comments: 14 pages, 10 figures, MNRAS accepted
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

The velocity of the inner ejecta of stripped-envelope core-collapse supernovae (CC-SNe) is studied by means of an analysis of their nebular spectra. Stripped-envelope CC-SNe are the result of the explosion of bare cores of massive stars ($\geq 8$ M$_{\odot}$), and their late-time spectra are typically dominated by a strong [O {\sc i}] $\lambda\lambda$6300, 6363 emission line produced by the innermost, slow-moving ejecta which are not visible at earlier times as they are located below the photosphere. A characteristic velocity of the inner ejecta is obtained for a sample of 56 stripped-envelope CC-SNe of different spectral types (IIb, Ib, Ic) using direct measurements of the line width as well as spectral fitting. For most SNe, this value shows a small scatter around 4500 km s$^{-1}$. Observations ($< 100$ days) of stripped-envelope CC-SNe have revealed a subclass of very energetic SNe, termed broad-lined SNe (BL-SNe) or hypernovae, which are characterised by broad absorption lines in the early-time spectra, indicative of outer ejecta moving at very high velocity ($v \geq 0.1 c$). SNe identified as BL in the early phase show large variations of core velocities at late phases, with some having much higher and some having similar velocities with respect to regular CC-SNe. This might indicate asphericity of the inner ejecta of BL-SNe, a possibility we investigate using synthetic three-dimensional nebular spectra.

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[4]  arXiv:0911.3809 [ps, pdf, other]
Title:The discovery of a massive white dwarf in the peculiar binary system HD 49798/RX J0648.0-4418
Authors: S.Mereghetti, A.Tiengo, P.Esposito, N.La Palombara (1), G.L.Israel, L.Stella (2) ((1) INAF-IASF Milano, (2) INAF, Oss. Astron. Roma)
Comments: Proceedings of the conference X-Ray Astronomy 2009, Present Status, multiwavelength approach and future perspectives, September 7 - 11, 2009, Bologna, Italy
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)

An XMM-Mewton observation performed in May 2008 has confirmed that the 13 seconds pulsations in the X-ray binary HD 49798/RX J0648.0-4418 are due to a rapidly rotating white dwarf. From the pulse time delays induced by the 1.55 days orbital motion, and the system's inclination, constrained by the duration of the X-ray eclipse discovered in this observation, we could derive a mass of 1.28+/-0.05 M_sun for the white dwarf. The future evolution of this post common envelope binary system will likely involve a new phase of mass accretion through Roche-lobe overflow that could drive the already massive white dwarf above the Chandrasekhar limit and produce a Type Ia supernova.

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[6]  arXiv:0911.3709 (cross-list from astro-ph.CO) [ps, pdf, other]
Title:Simulating X-ray Supercavities and Their Impact on Galaxy Clusters
Authors: Fulai Guo, William G. Mathews (UC Santa Cruz)
Comments: Submitted to ApJ. 11 pages, 6 figures
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)

Recent X-ray observations of hot gas in the galaxy cluster MS 0735.6+7421 reveal huge radio-bright, quasi-bipolar X-ray cavities having a total energy ~10^{62} ergs, the most energetic AGN outburst currently known. We investigate the evolution of this outburst with two-dimensional axisymmetric gasdynamical calculations in which the cavities are inflated by relativistic cosmic rays. Many key observational features of the cavities and associated shocks are successfully reproduced. The radial elongation of the cavities indicates that cosmic rays were injected into the cluster gas by a (jet) source moving out from the central AGN. AGN jets of this magnitude must be almost perfectly identically bipolar. The relativistic momentum of a single jet would cause a central AGN black hole of mass 10^9 M_{sun} to recoil at ~6000 km s^{-1}, exceeding kick velocities during black hole mergers, and be ejected from the cluster-center galaxy. When the cavity inflation is complete, 4PV underestimates the total energy received by the cluster gas. Deviations of the cluster gas from hydrostatic equilibrium are most pronounced during the early cavity evolution when the integrated cluster mass found from the observed gas pressure gradient can have systematic errors near the cavities of ~10-30%. The creation of the cavity with cosmic rays generates a long-lasting global cluster expansion that reduces the total gas thermal energy below that received from the cavity shock. One Gyr after this single outburst, a gas mass of ~ 6 \times 10^{11} M_{sun} is transported out beyond a cluster radius of 500 kpc. Such post-cavity outflows can naturally produce the discrepancy observed between the cluster gas mass fraction and the universal baryon fraction inferred from WMAP observations. (Abridged)

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