tag:blogger.com,1999:blog-2024170492534940602018-03-05T08:09:01.312-08:00High Energy Physics - PhenomenologySite for <a href="http://communitypeerreview.blogspot.com/">Community Peer Review</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.comBlogger11312125tag:blogger.com,1999:blog-202417049253494060.post-47587866057829080442013-08-06T00:15:00.027-07:002013-08-06T00:15:23.986-07:001011.3776 (Evgeny Akhmedov)<h2 class="title"><a href="http://arxiv.org/abs/1011.3776">Beta decay and other processes in strong electromagnetic fields</a> [<a href="http://arxiv.org/pdf/1011.3776">PDF</a>]</h2>Evgeny Akhmedov<a name='more'></a><blockquote class="abstract">We consider effects of the fields of strong electromagnetic waves on various characteristics of quantum processes. After a qualitative discussion of the effects of external fields on the energy spectra and angular distributions of the final-state particles as well as on the total probabilities of the processes (such as decay rates and total cross sections), we present a simple method of calculating the total probabilities of processes with production of non-relativistic charged particles. Using nuclear beta-decay as an example, we study the weak and strong field limits, as well as the field-induced beta-decay of nuclei stable in the absence of the external fields, both in the tunneling and multi-photon regimes. We also consider the possibility of accelerating forbidden nuclear beta-decays by lifting the forbiddeness due to the interaction of the parent or daughter nuclei with the field of a strong electromagnetic wave. It is shown that for currently attainable electromagnetic fields all effects on total beta-decay rates are unobservably small.</blockquote>View original: <a href="http://arxiv.org/abs/1011.3776">http://arxiv.org/abs/1011.3776</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-85575748494203153282013-08-06T00:15:00.025-07:002013-08-06T00:15:22.308-07:001308.0598 (The NNPDF Collaboration et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0598">Parton distributions with QED corrections</a> [<a href="http://arxiv.org/pdf/1308.0598">PDF</a>]</h2>The NNPDF Collaboration, Richard D. Ball, Valerio Bertone, Stefano Carrazza, Luigi Del Debbio, Stefano Forte, Alberto Guffanti, Nathan P. Hartland, Juan Rojo<a name='more'></a><blockquote class="abstract">We present a set of parton distribution functions (PDFs), based on the NNPDF2.3 set, which includes a photon PDF, and QED contributions to parton evolution. We describe the implementation of the combined QCD+QED evolution in the NNPDF framework. We then provide a first determination of the full set of PDFs based on deep-inelastic scattering data and LHC data for W and Z/gamma* Drell-Yan production, using leading-order QED and NLO or NNLO QCD. We compare the ensuing NNPDF2.3QED PDF set to the older MRST2004QED set. We perform a preliminary investigation of the phenomenological implications of NNPDF2.3QED: specifically, photon-induced corrections to direct photon production at HERA, and high-mass dilepton and W pair production at the LHC.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0598">http://arxiv.org/abs/1308.0598</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-1671585208209794592013-08-06T00:15:00.023-07:002013-08-06T00:15:21.362-07:001308.0605 (Mustafa A. Amin et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0605">A Clash of Kinks: Phase shifts in colliding non-integrable solitons</a> [<a href="http://arxiv.org/pdf/1308.0605">PDF</a>]</h2>Mustafa A. Amin, Eugene A. Lim, I-Sheng Yang<a name='more'></a><blockquote class="abstract">We derive a closed-form expression for the phase shift experienced by 1+1 dimensional kinks colliding at ultra-relativistic velocities (gamma v >> 1), valid for arbitrary periodic potentials. Our closed-form expression is the leading order result of a more general scattering theory of solitary waves described in a companion paper [Amin, Lim and Yang (2013)]. This theory relies on a small kinematic parameter 1/(gamma v) << 1 rather than a small parameter in the Lagrangian. Our analytic results can be directly extracted from the Lagrangian without solving the equation of motion. Based on our closed-form expression, we prove that kink-kink and kink-antikink collisions have identical phase shifts at leading order.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0605">http://arxiv.org/abs/1308.0605</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-30118184847784049742013-08-06T00:15:00.021-07:002013-08-06T00:15:20.506-07:001308.0606 (Mustafa A. Amin et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0606">A scattering theory of ultra-relativistic solitons</a> [<a href="http://arxiv.org/pdf/1308.0606">PDF</a>]</h2>Mustafa A. Amin, Eugene A. Lim, I-Sheng Yang<a name='more'></a><blockquote class="abstract">We construct a perturbative framework for understanding the collision of solitons (more precisely, solitary waves) in relativistic scalar field theories. Our perturbative framework is based on the suppression of the space-time interaction area proportional to 1/(gamma v), where v is the relative velocity of an incoming solitary wave and gamma = 1/sqrt(1-v^2) >> 1. We calculate the leading order results for collisions of (1+1) dimensional kinks in periodic potentials, and provide explicit, closed form expressions for the phase shift and the velocity change after the collisions. We find excellent agreement between our results and detailed numerical simulations. Crucially, our perturbation series is controlled by a kinematic parameter, and hence not restricted to small deviations around integrable cases such as the Sine-Gordon model.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0606">http://arxiv.org/abs/1308.0606</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-28586941990326814172013-08-06T00:15:00.019-07:002013-08-06T00:15:17.702-07:001308.0612 (Yang Bai et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0612">Fermion Portal Dark Matter</a> [<a href="http://arxiv.org/pdf/1308.0612">PDF</a>]</h2>Yang Bai, Joshua Berger<a name='more'></a><blockquote class="abstract">We study a class of simplified dark matter models in which one dark matter particle couples with a mediator and a Standard Model fermion. In such models, collider and direct detection searches probe complimentary regions of parameter space. For Majorana dark matter, direct detection covers the region near mediator-dark matter degeneracy, while colliders probe regions with a large dark matter and mediator mass splitting. For Dirac and complex dark matter, direct detection is effective for the entire region above the mass threshold, but colliders provide a strong bound for dark matter lighter than a few GeV. We also point out that dedicated searches for signatures with two jets or a mono-jet not coming from initial state radiation, along missing transverse energy can cover the remaining parameter space for thermal relic dark matter.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0612">http://arxiv.org/abs/1308.0612</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-60189786227677695682013-08-06T00:15:00.017-07:002013-08-06T00:15:15.460-07:001308.0617 (Shanshan Cao et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0617">Heavy quark dynamics and hadronization in ultra-relativistic heavy-ion<br /> collisions: collisional vs. radiative energy loss</a> [<a href="http://arxiv.org/pdf/1308.0617">PDF</a>]</h2>Shanshan Cao, Guang-You Qin, Steffen A. Bass<a name='more'></a><blockquote class="abstract">We study the dynamics of energy loss and flow of heavy quarks produced in ultra-relativistic heavy-ion collisions within the framework of a Langevin equation coupled to a (2+1)-dimensional viscous hydrodynamic model that simulates the space-time evolution of the produced hot and dense QCD matter. The classical Langevin approach is improved such that, apart from quasi-elastic scatterings, radiative energy loss is incorporated by treating gluon radiation as an additional force term. The hadronization of emitted heavy quarks is simulated via a hybrid fragmentation plus recombination model. Our calculation shows significant contribution from gluon radiation to heavy quark energy loss at high energies, and we find the recombination mechanism is important for heavy flavor meson production at intermediate energies. We present numerical results for the nuclear modification and elliptic flow of D mesons, which are consistent with measurements at both LHC and RHIC; predictions for B mesons are also provided.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0617">http://arxiv.org/abs/1308.0617</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-70820955067409476362013-08-06T00:15:00.015-07:002013-08-06T00:15:14.732-07:001308.0618 (Manoj Kaplinghat et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0618">Self-interacting Dark Matter Benchmarks</a> [<a href="http://arxiv.org/pdf/1308.0618">PDF</a>]</h2>Manoj Kaplinghat, Sean Tulin, Hai-Bo Yu<a name='more'></a><blockquote class="abstract">Dark matter self-interactions have important implications for the distributions of dark matter in the Universe, from dwarf galaxies to galaxy clusters. We present benchmark models that illustrate characteristic features of dark matter that is self-interacting through a new light mediator. These models have self-interactions large enough to change dark matter densities in the centers of galaxies in accord with observations, while remaining compatible with large-scale structure data and all astrophysical observations such as halo shapes and the Bullet Cluster. These observations favor a mediator mass in the 10 - 100 MeV range and large regions of this parameter space are accessible to direct detection experiments like LUX, SuperCDMS, and XENON1T.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0618">http://arxiv.org/abs/1308.0618</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-12869511889188715642013-08-06T00:15:00.013-07:002013-08-06T00:15:13.808-07:001308.0697 (T. M. Aliev et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0697">Electromagnetic transitions among octet and decuplet baryons in QCD</a> [<a href="http://arxiv.org/pdf/1308.0697">PDF</a>]</h2>T. M. Aliev, Y. Oktem, M. Savci<a name='more'></a><blockquote class="abstract">The magnetic dipole G_M(Q^2), electric quadrupole G_E(Q^2), and Coulomb quadrupole G_C(Q^2) form factors, describing the spin-3/2 to spin-1/2 electromagnetic transitions, are investigated within the light cone QCD sum rules. The Q^2 dependence of these form factors, as well as ratios of electric quadrupole and Coulomb quadrupole form factors to the magnetic dipole form factors are studied. We also compare our results on the magnetic dipole form factor with the prediction of the covariant spectator quark model.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0697">http://arxiv.org/abs/1308.0697</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-51711029950411436952013-08-06T00:15:00.011-07:002013-08-06T00:15:13.041-07:001308.0700 (Duojie Jia et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0700">Dynamical bag in a chiral quark model</a> [<a href="http://arxiv.org/pdf/1308.0700">PDF</a>]</h2>Duojie Jia, LianChun Yu, Rui-Bin Wan<a name='more'></a><blockquote class="abstract">A type of bag function is proposed to make the MIT bag surface of baryon dynamical. It is illustrated through renormalization of the quark field that the softening of chiral bag gives rise to a model of chiral quark with effectively-generated mass of quark, in which confined quark moves in the background of nonlinear pion. A prediction of bag constant $B$ $\simeq 2f_{\pi}^{2}m_{\pi}^{2}\allowbreak $ is made. With two free parameters, the self-coupling $e$ of pion and the confining scale $a$, the computed mass, the charge root-mean-square radius and magnetic moment of the proton are in good agreement with the experimental values.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0700">http://arxiv.org/abs/1308.0700</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-81580754737539959622013-08-06T00:15:00.009-07:002013-08-06T00:15:11.918-07:001308.0736 (V. Uzhinsky)<h2 class="title"><a href="http://arxiv.org/abs/1308.0736">Toward UrQMD Model Description of pp and pC Interactions at High<br /> Energies</a> [<a href="http://arxiv.org/pdf/1308.0736">PDF</a>]</h2>V. Uzhinsky<a name='more'></a><blockquote class="abstract">It is found that UrQMD model version 3.3 does not describe NA61/SHINE Collaboration data on \pi-meson production in pp interactions at energies 20 - 80 GeV. At the same time, it describes quite well the NA49 Collaboration data on the meson production in pp and pC interactions at 158 GeV. The Collaborations do not consider feedback of \eta-meson decays. All versions of the UrQMD model assume that \eta-mesons are "stable". An inclusion of the decays into calculations leads to 2--3 % increase of the meson production which is not enough for description of the data. Possible ways of the model improvements are considered. Conclusions of the paper are: accounting of \eta-meson decays is not essential for a description of experimental data; a new tuning of the UrQMD model parameters is needed for a successful description of pp and pC interactions at high energies; inclusion of the low mass diffraction dissociation in the UrQMD model would be desirable.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0736">http://arxiv.org/abs/1308.0736</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-26576156432387794172013-08-06T00:15:00.007-07:002013-08-06T00:15:11.113-07:001308.0772 (Kai Yi)<h2 class="title"><a href="http://arxiv.org/abs/1308.0772">Experimental Review of Structures in the $J/ψφ$ Mass Spectrum</a> [<a href="http://arxiv.org/pdf/1308.0772">PDF</a>]</h2>Kai Yi<a name='more'></a><blockquote class="abstract">The discovery of numerous new charmonium-like structures since 2003 have revitalized interest in exotic meson spectroscopy. These structures do not fit easily into the conventional charmonium model, and proposals like four-quark states, hybrids, and re-scattering effects have been suggested as explanations. Since 2009, several new structures were reported in the $J/\psi\phi$ mass spectrum with the following characteristics: they are the first ones reported decaying into two heavy mesons which contain both a $c\bar{c}$ pair and a $s\bar{s}$ pair; and their masses are well beyond the open charm pair threshold. Conventional $c\bar{c}$ states with a mass beyond the $J/\psi\phi$ threshold are not expected to decay into this channel and the width is expected to be large, thus they are good candidates for exotic mesons. My focus in this article is to review the recent developments on the structures in the $J/\psi\phi$ mass spectrum from CDF, Belle and LHCb.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0772">http://arxiv.org/abs/1308.0772</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-60521404613705079192013-08-06T00:15:00.005-07:002013-08-06T00:15:10.461-07:001308.0785 (E. Molnár et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0785">On the relative importance of second-order terms in relativistic<br /> dissipative fluid dynamics</a> [<a href="http://arxiv.org/pdf/1308.0785">PDF</a>]</h2>E. Molnár, H. Niemi, G. S. Denicol, D. H. Rischke<a name='more'></a><blockquote class="abstract">In Denicol et al., Phys. Rev. D 85, 114047 (2012), the equations of motion of relativistic dissipative fluid dynamics were derived from the relativistic Boltzmann equation. These equations contain a multitude of terms of second order in Knudsen number, in inverse Reynolds number, or their product. Terms of second order in Knudsen number give rise to non-hyperbolic (and thus acausal) behavior and must be neglected in (numerical) solutions of relativistic dissipative fluid dynamics. The coefficients of the terms which are of the order of the product of Knudsen and inverse Reynolds numbers have been explicitly computed in the above reference, in the limit of a massless Boltzmann gas. Terms of second order in inverse Reynolds number arise from the collision term in the Boltzmann equation, upon expansion to second order in deviations from the single-particle distribution function in local thermodynamical equilibrium. In this work, we compute these second-order terms for a massless Boltzmann gas with constant scattering cross section. Consequently, we assess their relative importance in comparison to the terms which are of the order of the product of Knudsen and inverse Reynolds numbers.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0785">http://arxiv.org/abs/1308.0785</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-33721403484830259582013-08-06T00:15:00.003-07:002013-08-06T00:15:09.698-07:001308.0792 (Xiaochuan Lu et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0792">A Natural Higgs Mass in Supersymmetry from Non-Decoupling Effects</a> [<a href="http://arxiv.org/pdf/1308.0792">PDF</a>]</h2>Xiaochuan Lu, Hitoshi Murayama, Joshua T. Ruderman, Kohsaku Tobioka<a name='more'></a><blockquote class="abstract">The Higgs mass implies fine-tuning for minimal theories of weak scale supersymmetry (SUSY). Non-decoupling effects can boost the Higgs mass when new states interact with the Higgs, but new sources of SUSY breaking that accompany such extensions threaten naturalness. We show that a singlet with a Dirac mass can increase the Higgs mass while maintaining naturalness in the presence of large SUSY breaking in the singlet sector. We explore the modified Higgs phenomenology of this scenario, which we call the "Dirac NMSSM."</blockquote>View original: <a href="http://arxiv.org/abs/1308.0792">http://arxiv.org/abs/1308.0792</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-61097847432417525262013-08-06T00:15:00.001-07:002013-08-06T00:15:09.025-07:001308.0816 (Alakabha Datta et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0816">Higgs Vacuum Stability in $B-L$ extended Standard Model</a> [<a href="http://arxiv.org/pdf/1308.0816">PDF</a>]</h2>Alakabha Datta, A. Elsayed, S. Khalil, A. Moursy<a name='more'></a><blockquote class="abstract">We study vacuum stability of B-L extension of the Standard Model (SM) and its supersymmetric version. We show that the generation of non-vanishing neutrino masses through TeV inverse seesaw mechanism leads to a cutoff scale of SM Higgs potential stability of order 10^5 GeV. However, in the non-supersymmetric B-L model, we find that the mixing between the SM-like Higgs and the B-L Higgs plays a crucial role in alleviating the vacuum stability problem. We also provide the constraints of stabilizing the Higgs potential in the supersymmetric B-L model.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0816">http://arxiv.org/abs/1308.0816</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-83473498728178210062013-08-06T00:00:00.031-07:002013-08-06T00:00:53.436-07:001308.0836 (Amr El-Zant et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0836">Warm Dark Matter in B-L Inverse Seesaw</a> [<a href="http://arxiv.org/pdf/1308.0836">PDF</a>]</h2>Amr El-Zant, Shaaban Khalil, Arunansu Sil<a name='more'></a><blockquote class="abstract">We show that a standard model gauge singlet fermion field, with mass of order keV or larger, and involved in the inverse seesaw mechanism of light neutrino mass generation, can be a good warm dark matter candidate. Our framework is based on $B-L$ extension of the Standard Model and the construction ensures the absence of any mixing between active neutrinos and the aforementioned dark matter field. This circumvents the usual constraints on the mass of warm dark matter imposed from X-rays. We show that over-abundance of thermally produced warm dark matter (which nevertheless do not reach chemical equilibrium) can be reduced to an acceptable range in the presence of a moduli field decaying into radiation --- though only when the reheating temperature is low enough. Our warm dark matter candidate can also be produced non-thermally, directly from the decay of the moduli field during reheating. In this case, obtaining the right amount of relic abundance of our dark matter candidate, while keeping the reheating temperature high enough as to be consistent with Big Bang nuceosynthesis bounds, places constraints on the branching ratio for the decay of the moduli field into dark matter.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0836">http://arxiv.org/abs/1308.0836</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-33542576984770106062013-08-06T00:00:00.029-07:002013-08-06T00:00:52.463-07:001308.0845 (Nathaniel Craig et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0845">Multi-Lepton Signals of Top-Higgs Associated Production</a> [<a href="http://arxiv.org/pdf/1308.0845">PDF</a>]</h2>Nathaniel Craig, Michael Park, Jessie Shelton<a name='more'></a><blockquote class="abstract">We evaluate the potential to measure ttbar H associated production at the LHC using non-resonant multi-lepton final states in conjunction with two or more b-tags. The multi-lepton ttbar H signal arises predominantly from H to tau tau and H to WW^* alongside the semi-leptonic or fully leptonic decay of the ttbar pair. We demonstrate the power of a multi-lepton search for ttbar H associated production by recasting the CMS b-tagged multi-lepton search with 19.5 fb^-1 of 8 TeV data to obtain an observed (expected) limit of 4.7 (6.6) times the Standard Model rate, comparable to ongoing searches in 4b and bb gamma gamma final states. Sensitivity can be further improved by the addition of exclusive channels involving same-sign dileptons. We recast the CMS b-tagged same-sign dilepton search with 10.5 fb^-1 of 8 TeV data to set limits on ttbar H associated production, and approximately combine the two searches by calculating the fraction of same-sign dilepton signal events which do not satisfy multi-lepton selection criteria. We estimate an expected total non-resonant leptonic reach of mu < 5.0 times the Standard Model rate in 20 fb^-1 of 8 TeV data, with improvements possible.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0845">http://arxiv.org/abs/1308.0845</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-57002924086325430232013-08-06T00:00:00.027-07:002013-08-06T00:00:51.400-07:001308.0860 (Luis P. Chimento et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0860">Nonbaryonic dark matter and scalar field coupled with a transversal<br /> interaction plus decoupled radiation</a> [<a href="http://arxiv.org/pdf/1308.0860">PDF</a>]</h2>Luis P. Chimento, Martín G. Richarte<a name='more'></a><blockquote class="abstract">We analyze a universe filled with interacting dark matter, a scalar field accommodated as dark radiation along with dark energy plus a decoupled radiation term within the framework of spatially flat Friedmann-Robertson-Walker (FRW) spacetime. We work in a three-dimensional internal space spanned by the interaction vector and use a transversal interaction $\mathbf{Q_t}$ for solving the source equation in order to find all the interacting component energy densities. We asymptotically reconstruct the scalar field and potential from an early radiation era to the late dominate dark energy one, passing through an intermediate epoch dominated by dark matter. We apply the $\chi^{2}$ method to the updated observational Hubble data for constraining the cosmic parameters, contrast with the Union 2 sample of supernovae, and analyze the amount of dark energy in the radiation era. It turns out that our model fulfills the severe bound of $\Omega_{\rm \phi}(z\simeq 1100)<0.018$ at $2\sigma$ level, is consistent with the recent analysis that includes cosmic microwave background anisotropy measurements from the Atacama Cosmology Telescope and the South Pole Telescope along with the future constraints achievable by Planck and CMBPol experiments, and satisfies the stringent bound $\Omega_{\rm \phi}(z\simeq 10^{10})<0.04$ at $2\sigma$ level in the big-bang nucleosynthesis epoch.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0860">http://arxiv.org/abs/1308.0860</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-66971136562213477372013-08-06T00:00:00.025-07:002013-08-06T00:00:50.357-07:001308.0887 (K. Azizi et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0887">Thermal properties of $D_2^*(2460)$ and $D_{s2}^*(2573)$ tensor mesons</a> [<a href="http://arxiv.org/pdf/1308.0887">PDF</a>]</h2>K. Azizi, H. Sundu, A. Turkan, E. Veli Veliev<a name='more'></a><blockquote class="abstract">We investigate the masses and decay constants of the heavy-light tensor mesons $D_2^*(2460)$ and $D_{s2}^*(2573)$ in the framework of thermal QCD sum rules. Taking into account additional operators arising at finite temperature, we evaluate Wilson expansion for two-point correlation function associated with the above mentioned mesons. We observe that the values of the masses and decay constants decrease considerably at near to the critical temperature. The decay constants attain roughly to 25% of their values in vacuum, while the masses decrease about 39% and 37% for $D_2^*$ and $D_{s2}^*$ states, respectively. This can be considered as a sign of phase transition to the quark-gluon plasma.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0887">http://arxiv.org/abs/1308.0887</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-80300996963782259752013-08-06T00:00:00.023-07:002013-08-06T00:00:49.355-07:001308.0891 (Radovan Dermisek et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0891">Coleman-Weinberg Higgs</a> [<a href="http://arxiv.org/pdf/1308.0891">PDF</a>]</h2>Radovan Dermisek, Tae Hyun Jung, Hyung Do Kim<a name='more'></a><blockquote class="abstract">We discuss an extension of the standard model by fields not charged under standard model gauge symmetry in which the electroweak symmetry breaking is driven by the Higgs quartic coupling itself without the need for a negative mass term in the potential. This is achieved by a scalar field S with a large coupling to the Higgs field at the electroweak scale which is driven to very small values at high energies by the gauge coupling of a hidden symmetry under which S is charged. This model remains perturbative all the way to the Planck scale. The Higgs boson is fully SM-like in its couplings to fermions and gauge bosons. The only modified couplings are the effective cubic and quartic self-couplings of the Higgs boson, which are enhanced by 67% and 267% respectively.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0891">http://arxiv.org/abs/1308.0891</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-19862334743516024472013-08-06T00:00:00.021-07:002013-08-06T00:00:48.396-07:001308.0924 (Pranati K. Rath et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0924">Testing the Dipole Modulation Model in CMBR</a> [<a href="http://arxiv.org/pdf/1308.0924">PDF</a>]</h2>Pranati K. Rath, Pankaj Jain<a name='more'></a><blockquote class="abstract">The hemispherical power asymmetry, observed in the CMBR data, has generally been interpreted in terms of the dipole modulation model for the temperature fluctuations. Here we point out that this model leads to several predictions, which can be directly tested in the current data. We also suggest tests of the hemispherical power asymmetry in real space. We do not find a significant signal of the dipole modulation model in WMAP and PLANCK data. Hence the detected hemispherical anisotropy cannot be consistently represented in terms of the dipole modulation model. It probably represents a more complex anisotropic model.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0924">http://arxiv.org/abs/1308.0924</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-59184428743172691592013-08-06T00:00:00.019-07:002013-08-06T00:00:47.325-07:001308.0947 (Dmitri Diakonov et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0947">A theory of baryon resonances at large N_c</a> [<a href="http://arxiv.org/pdf/1308.0947">PDF</a>]</h2>Dmitri Diakonov, Victor Petrov, Alexey A. Vladimirov<a name='more'></a><blockquote class="abstract">At large number of colors, N_c quarks in baryons are in a mean field of definite space and flavor symmetry. We write down the general Lorentz and flavor structure of the mean field, and derive the Dirac equation for quarks in that field. The resulting baryon resonances exhibit an hierarchy of scales: The crude mass is O(N_c), the intrinsic quark excitations are O(1), and each intrinsic quark state entails a finite band of collective excitations that are split as O(1/N_c). We build a (new) theory of those collective excitations, where full dynamics is represented by only a few constants. In a limiting (but unrealistic) case when the mean field is spherically-and flavor-symmetric, our classification of resonances reduces to the SU(6) classification of the old non-relativistic quark model. Although in the real world N_c is only three, we obtain a good accordance with the observed resonance spectrum up to 2 GeV.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0947">http://arxiv.org/abs/1308.0947</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-61965784935411879812013-08-06T00:00:00.017-07:002013-08-06T00:00:46.413-07:001308.0951 (Sonja Esch et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0951">Detection prospects of singlet fermionic dark matter</a> [<a href="http://arxiv.org/pdf/1308.0951">PDF</a>]</h2>Sonja Esch, Michael Klasen, Carlos E. Yaguna<a name='more'></a><blockquote class="abstract">A singlet fermion which interacts only with a new singlet scalar provides a viable and minimal scenario that can explain the dark matter. The singlet fermion is the dark matter particle whereas the new scalar mixes with the Higgs boson providing a link between the dark matter sector and the Standard Model. In this paper, we present an updated analysis of this model focused on its detection prospects. Both, the parity-conserving case and the most general case are considered. First, the full parameter space of the model is analyzed, and the regions compatible with the dark matter constraint are obtained and characterized. Then, the implications of current and future direct detection experiments are taken into account. Specifically, we determine the regions of the multidimensional parameter space that are currently excluded and those that are going to be probed by next generation experiments. Finally, indirect detection prospects are discussed and the expected signal at neutrino telescopes is calculated.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0951">http://arxiv.org/abs/1308.0951</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-27848820959608317642013-08-06T00:00:00.015-07:002013-08-06T00:00:45.490-07:001308.0960 (Tian Wei-Zhao et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0960">Bottomonium states versus recent experimental observations in the<br /> QCD-inspired potential model</a> [<a href="http://arxiv.org/pdf/1308.0960">PDF</a>]</h2>Tian Wei-Zhao, Cao Lu, Yang You-Chang, Chen Hong<a name='more'></a><blockquote class="abstract">In the QCD-inspired potential model where the quark-antiquark interaction consists of the usual one-gluon-exchange and the mixture of long-range scalar and vector linear confining potentials with the lowest order relativistic correction, we investigate the mass spectra and electromagnetic processes of a bottomonium system by using the Gaussian expansion method. It reveals that the vector component of the mixing confinement is anticonfining and takes around 18.51% of the confining potential. Combining the new experimental data released by Belle, BaBar and LHC, we systematically discuss the energy levels of the bottomonium states and make the predictions of the electromagnetic decays for further experiments.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0960">http://arxiv.org/abs/1308.0960</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-42397415175206344582013-08-06T00:00:00.013-07:002013-08-06T00:00:44.488-07:001308.1021 (R. Nevzorov et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.1021">Exotic Higgs decays in the E6 inspired SUSY models</a> [<a href="http://arxiv.org/pdf/1308.1021">PDF</a>]</h2>R. Nevzorov, S. Pakvasa<a name='more'></a><blockquote class="abstract">We study the decays of the SM-like Higgs state within the E6 inspired supersymmetric (SUSY) models with exact custodial symmetry that forbids tree-level flavor-changing transitions and the most dangerous baryon and lepton number violating operators. In these models there are two states which are absolutely stable and can contribute to the dark matter density. One of them is the lightest SUSY particle (LSP) which is expected to be lighter than 1 eV forming hot dark matter in the Universe. The presence of another stable neutral state allows to account for the observed cold dark matter density. In the considered SUSY models next--to--lightest SUSY particle (NLSP) also tend to be light. We argue that the NLSP with GeV scale mass can result in the substantial branching ratio of the nonstadard decays of the lightest Higgs boson.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1021">http://arxiv.org/abs/1308.1021</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-202417049253494060.post-13413866249055107832013-08-06T00:00:00.011-07:002013-08-06T00:00:43.572-07:001308.1029 (Renata Zukanovich Funchal et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.1029">The Physics of Neutrinos</a> [<a href="http://arxiv.org/pdf/1308.1029">PDF</a>]</h2>Renata Zukanovich Funchal, Benoit Schmauch, Gaëlle Giesen<a name='more'></a><blockquote class="abstract">These lecture notes are based on a course given at Institut de Physique Th\'eorique of CEA/Saclay in January/February 2013.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1029">http://arxiv.org/abs/1308.1029</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0