Improved transfer matrix method without numerical instability

A new improved transfer matrix method (TMM) is presented. It is shown that the method not only overcomes the numerical instability found in the original TMM, but also greatly improves the scalability of computation. The new improved TMM has no extra cost of computing time as the length of homogeneous scattering region becomes large. The comparison between the scattering matrix method(SMM) and our new TMM is given. It clearly shows that our new method is much faster than SMM.Comment: 5 pages,3 figure

Pair Production of MSSM Higgs Bosons in the Non-decoupling Region at the LHC

We consider the Higgs boson signals from pair production at the LHC within the framework of the MSSM in the non-decoupling (low-m_A) region. In light of the recent observation of a SM-like Higgs boson, we argue that the exploration for Higgs pair production at the LHC is a crucial next step to probe the MSSM Higgs sector. We emphasize that the production of H^\pm A^0 and H^{+}H^{-} depends only on the electroweak gauge couplings while all the leading Higgs production channels via gluon fusion, vector-boson fusion, and Higgsstrahlung depend on additional free Higgs sector parameters. In the non-decoupling region, the five MSSM Higgs bosons are all relatively light and pair production signals may be accessible. We find that at the 8 TeV LHC, a 5\sigma signal for H^\pm A^0, H^\pm h^0 -> \tau^{\pm}\nu b\bar b and H^{+}H^{-} -> \tau^{+}\nu \tau^{-}\nu are achievable with an integrated luminosity of 7 (11) fb^{-1} and 24 (48) fb^{-1}, respectively for m_A=95 (130) GeV. At the 14 TeV LHC, a 5\sigma signal for these two channels would require as little as 4 (7) fb^{-1} and 10 (19) fb^{-1}, respectively.Comment: 20 pages, 8 figures and 3 tables. Version to appear in PR

X(1835): A Natural Candidate of η′\eta^\prime's Second Radial Excitation

Recently BES collaboration observed one interesting resonance X(1835). We point out that its mass, total width, production rate and decay pattern favor its assignment as the second radial excitation of $\eta^\prime$ meson very naturally

Probing the electron-phonon coupling in ozone-doped graphene by Raman spectroscopy

We have investigated the effects of ozone treatment on graphene by Raman scattering. Sequential ozone short-exposure cycles resulted in increasing the $p$ doping levels as inferred from the blue shift of the 2$D$ and $G$ peak frequencies, without introducing significant disorder. The two-phonon 2$D$ and 2$D'$ Raman peak intensities show a significant decrease, while, on the contrary, the one-phonon G Raman peak intensity remains constant for the whole exposure process. The former reflects the dynamics of the photoexcited electrons (holes) and, specifically, the increase of the electron-electron scattering rate with doping. From the ratio of 2$D$ to 2$D$ intensities, which remains constant with doping, we could extract the ratio of electron-phonon coupling parameters. This ratio is found independent on the number of layers up to ten layers. Moreover, the rate of decrease of 2$D$ and 2$D'$ intensities with doping was found to slowdown inversely proportional to the number of graphene layers, revealing the increase of the electron-electron collision probability

Field-induced structure transformation in electrorheological solids

We have computed the local electric field in a body-centered tetragonal (BCT) lattice of point dipoles via the Ewald-Kornfeld formulation, in an attempt to examine the effects of a structure transformation on the local field strength. For the ground state of an electrorheological solid of hard spheres, we identified a novel structure transformation from the BCT to the face-centered cubic (FCC) lattices by changing the uniaxial lattice constant c under the hard sphere constraint. In contrast to the previous results, the local field exhibits a non-monotonic transition from BCT to FCC. As c increases from the BCT ground state, the local field initially decreases rapidly towards the isotropic value at the body-centered cubic lattice, decreases further, reaching a minimum value and increases, passing through the isotropic value again at an intermediate lattice, reaches a maximum value and finally decreases to the FCC value. An experimental realization of the structure transformation is suggested. Moreover, the change in the local field can lead to a generalized Clausius-Mossotti equation for the BCT lattices.Comment: Submitted to Phys. Rev.

Higgs Boson Search Sensitivity in the H→WWH \to WW Dilepton Decay Mode at s=7\sqrt s = 7 and 10 TeV

Prospects for discovery of the standard model Higgs boson are examined at center of mass energies of $7$ and $10$ TeV at the CERN Large Hadron Collider. We perform a simulation of the signal and principal backgrounds for Higgs boson production and decay in the $W^+ W^-$ dilepton mode, finding good agreement with the ATLAS and CMS collaboration estimates of signal significance at 14 TeV for Higgs boson masses near $m_H = 160$~GeV. At the lower energy of $7$~TeV, using the same analysis cuts as these collaborations, we compute expected signal sensitivities of about $2$ standard deviations ($\sigma$'s) at $m_H = 160$~GeV in the ATLAS case, and about 3.6~$\sigma$ in the CMS case for $1$~fb$^{-1}$ of integrated luminosity. Integrated luminosities of 8~$\rm{fb}^{-1}$ and 3~$\rm{fb}^{-1}$ are needed in the ATLAS case at $7$ and $10$~TeV, respectively, for $5~\sigma$ level discovery. In the CMS case, the numbers are 2~$\rm{fb}^{-1}$ and 1~$\rm{fb}^{-1}$ at $7$ and $10$~TeV. Our different stated expectations for the two experiments arise from the more restrictive analysis cuts in the CMS case. Recast as exclusion limits, our results show that with $1~{\rm fb}^{-1}$ of integrated luminosity at 7~TeV, the LHC may be able to exclude $m_H$ values in the range 160 to 180~GeV provided no signal is seen.Comment: 29 pages, 8 figures. New results on estimated discovery reach for both CMS and ATLAS, as well as exclusion limits, along with comparisons with Tevatron possibilities. References added