125836359
Test of QCD using multijets in neutral current DIS at HERA
117840720
Top Quark Production at the Tevatron Collider
Top quark physics has been a rich testing ground for the standard model since the top quark discovery in 1995. The large mass of top quark suggests that it could play a special role in searches for new phenomena. In this paper I provide an overview of recent top quark production cross section measurements from both CDF and D0 collaborations and also some new physics searches done in the top quark sector.
18868106
Are Gamma-Ray Bursts Standard Candles?
By dividing a sample of 48 long-duration gamma-ray bursts (GRBs) into four groups with redshift from low to high and fitting each group with the Amati relation log Eiso = a + b log Epeak, I find that parameters a and b vary with the mean redshift of the GRBs in each group systematically and significantly. The results suggest that GRBs evolve strongly with the cosmic redshift and hence are not standard candles.
122970197
Multijet production in neutral current deep inelastic scattering at HERA and determination of alpha(s)
Multijet production rates in neutral current deep inelastic scattering (DIS) have been measured in the range of exchanged boson virtualities 10<Q2<5000 GeV2. The data were taken at the ep collider HERA with centre-of-mass energy using the ZEUS detector and correspond to an integrated luminosity of 82.2 pb-1. Jets were identified in the Breit frame using the kT cluster algorithm in the longitudinally invariant inclusive mode. Measurements of differential multijet cross sections are presented as functions of jet transverse energy , pseudorapidity and Q2 with and . Next-to-leading-order QCD calculations describe the data well. The value of the strong coupling constant αs(MZ), determined from the ratio of the trijet to dijet cross sections, is .
116928402
Introduction to holographic superconductor models
In the last years it has been shown that some properties of strongly coupled superconductors can be potentially described by classical general relativity living in one higher dimension, which is known as holographic superconductors. This paper gives a quick and introductory overview of some holographic superconductor models with s-wave, p-wave and d-wave orders in the literature from point of view of bottom-up, and summarizes some basic properties of these holographic models in various regimes. The competition and coexistence of these superconductivity orders are also studied in these superconductor models.
118380628
Binary interactions on the calibrations of star formation rate
Using the Yunnan evolutionary population synthesis (EPS) models with and without binary interactions, we present the luminosity of H alpha recombination line (L-H alpha), the luminosity of [O II]lambda 3727 forbidden line doublet (L-[O II]), the ultraviolet (UV) fluxes at 1500 and 2800 angstrom (L-i,L-UV) and far-infrared flux (L-FIR) for burst, S0, Sa-Sd and Irr galaxies, and present the calibrations of star formation rate (SFR) in terms of these diagnostics. By comparison, we find that binary interactions lower the SFR versus L-H alpha and SFR versus L-[O II] conversion factors by similar to 0.2 dex. The main reason is that binary interactions raise the UV flux (shortwards of the Lyman limit) of the stellar population (SP) in the age range 6.7 < log t/yr < 8.4 and thus more ionizing photons are present in the nebula. Moreover, binary interactions do not significantly vary the calibrations of SFR in terms of L-i,L-UV. This is because binary interactions raise the flux at 1500 angstrom of the SP in the range 8.75 < log t/yr < 9.2 and the maximal difference is about 1 dex. In addition, binary interactions have little effect on the flux at 2800 angstrom. At last, the calibration of SFR from L-FIR is almost unaffected by binary interactions. This is caused by the fact that binary interactions almost do not affect the bolometric magnitudes of SPs. We also discuss the effects of initial mass function (IMF), gas-recycle assumption and EPS models [including GISSEL98 (Galaxy Isochrone Synthesis Spectral Evolution Library), BC03, STARBURST99, POPSTAR and PEGASE models] on these SFR calibrations. Comparing the results obtained by using the Salpeter (hereafter S55) IMF with those by using the Miller & Scalo (hereafterMS79) IMF, we find that the SFR versus L-H alpha and SFR versus L-[O II] conversion factors obtained by using the S55 IMF are greater by 0.4 and 0.2 dex than those by using the MS79 IMF for the Yunnan models with and without binary interactions, respectively. The SFR versus L-i,L-UV and SFR versus L-FIR conversion factors by using the S55 IMF are larger by an amount of 0.2 dex than the corresponding ones by using the MS79 IMF. The inclusion of gas-recycle assumption only lowers these SFR calibrations at faint SFR. Moreover, comparing the results when using different EPS models, we find that the differences in the SFR versus L-H alpha and SFR versus L-[O II] conversion factors reach similar to 0.7 and 0.9 dex, the difference in the SFR versus L-FIR conversion factor reaches 0.4 and 0.8 dex, and the differences in the SFR versus L-i,L-UV conversion factors reach 0.3 and 0.2 dex when using the S55 and non-S55 IMFs (including Chabrier, Kroupa-Aarseth-Hurley, Kroupa-Tout-Gilmore and Miller-Scalo IMFs, partly caused by the difference in the IMF), respectively. At last, we give the conversion coefficients between SFR and these diagnostics for all models.
119793175
Studies of dijet and trijet production in ep interactions at HERA
Measurements of dijet and trijet production in photoproduction, deep inelastic scattering and in the transition region between them, performed with the H1 and ZEUS detector at HERA are presented. The predictions of next-to-leading-order perturbative QCD are compared to the measured cross sections and found to be compatible with the data over a wide kinematic range.PACS: 12.38.Qk Experimental test – 13.60.Hb Total and inclusive cross sections