119311107
$B_s$ Semileptonic Decays to $D_s$ and $D_s^*$ in Bethe-Salpeter Method
Using the relativistic Bethe-Salpeter method, the electron energy spectrum and the semileptonic decay widths of $B^0_s\to D^-_s \ell^+{\nu_\ell}$ and $B^0_s\to D_s^{*-}\ell^+{\nu_\ell}$ are calculated. We obtained large branching ratios, $Br(B_s\to D_se\nu_e)=(2.85\pm0.35)% $ and $Br (B_s\to D_s^*e\nu_e)=(7.09\pm0.88)%$, which can be easily detected in the future experiment.
118388877
Lepton-number violating four-body decays of heavy mesons
A bstractNeutrinoless hadron Lepton Number Violating (LNV) decays can be induced by virtual Majorana neutrino, which in turn indubitably show the Majorana nature of neutrinos. Many three-body LNV processes and Lepton Flavour Violating (LFV) processes have been studied extensively in theory and by experiment. As a supplement, we here study 75 four-body LNV (LFV) processes from heavy pseudoscalar B and D decays. Most of these processes have not been studied in theory and searched for in experiment, while they may have sizable decay rates. Since the four-body decay modes have the same vertexes and mixing parameters with three-body cases, so their branching fractions are comparable with the corresponding three-body decays. We calculate their decay widths and branching fractions with current bounds on heavy Majorana neutrino mixing parameters, and estimate some channels’ reconstruction events using the current experimental data from Belle.
119192406
Rotating a curvaton brane in a warped throat
In this paper we study a curvaton model obtained by considering a probe anti-D3-brane with angular motion at the bottom of a KS throat with approximate isometries. We calculate the spectrum of curvature perturbations and the non-Gaussianities of this model. Specifically, we consider the limit of relativistic rotation of the curvaton brane which leads to a small sound speed, and thus it can be viewed as an implementation of the DBI-curvaton mechanism. We find that the primordial power spectrum is nearly scale-invariant while the non-Gaussianity of local type is sizable and that of equilateral type is usually large and negative. Moreover, we study both the theoretical and observational constraints on this model, and find that there exists a sizable allowed region for the phase space of this model.
118406545
Next-to-leading order QCD corrections to the top quark decay via the flavor-changing neutral-current operators with mixing effects
Detailed calculations of the complete $\mathcal{O}({\ensuremath{\alpha}}_{s})$ corrections to the top-quark decay widths $\ensuremath{\Gamma}(t\ensuremath{\rightarrow}q+V)$ with $V=g$, $\ensuremath{\gamma}$, $Z$, and $q=u$, $c$ are presented. Besides describing in detail the calculations in our previous work [Phys. Rev. Lett. 102, 072001 (2009)], we also include the mixing effects of the flavor-changing neutral-current operators for $t\ensuremath{\rightarrow}q+\ensuremath{\gamma}$ and $t\ensuremath{\rightarrow}q+Z$, which were not considered previously. We show that the mixing effects can either be large or small depending on the values of various anomalous couplings and thereby increase or decrease the branching ratios for $t\ensuremath{\rightarrow}q+\ensuremath{\gamma}$ and $t\ensuremath{\rightarrow}q+Z$.
41278561
The silicon matrix for the prototype for the Dark Matter Particle Explorer
In this paper, a silicon matrix detector is described and the results of the cosmic ray test are given. The silicon matrix is composed by the 180 silicon PIN detectors, which covers an area of 32 * 20cm2. The data of whole detectors is read out by the ASIC chips, and suppressed by an FPGA. In the test system, the trigger is given by two plastic scintillators, which are placed above and beneath the silicon matrix. The MIPs energy spectrum is shown in this paper. In further test, a small plastic scintillator is inserted to give a differential cosmic ray counting response.
117031507
Preheating in a DBI Inflation Model
We study the preheating process in a model of DBI inflation with a DBI-type inflaton coupling to a canonical entropy field. At the end of inflation, the inflaton field oscillates around its vacuum which can arise from an infrared cutoff parameter on the warp factor and correspondingly the evolution of its fluctuations can be approximately described by a generalized Hill's equation in third order. We study the field fluctuations numerically and show that they could grow exponentially since the instability bands commonly exist in the DBI models if the amplitudes of background oscillations are of order or larger than the cutoff parameter. Our numerical result also reveals that the particle excitation of the matter field is more dramatic than that in usual case since the parametric resonance lasts longer when the effect of a warp factor is taken into account. Therefore, we conclude that the preheating process in the model of DBI inflation could be more efficient than that in standard inflation models.
54954874
Stout-link smearing in lattice fermion actions
The properties of the momentum-space quark propagator in the Landau gauge are studied for the overlap quark action in quenched lattice QCD. Numerical calculations are performed over four ensembles of gauge configurations, where three are smeared using either 1, 3, or 6 sweeps of stout-link smearing. We calculate the nonperturbative wave-function renormalization function Z(p) and the nonperturbative mass function M(p) for a variety of bare quark masses. We find that the wave-function renormalization function is slightly sensitive to the number of stout-link smearing sweeps. For the mass function we find the effect of the stout-link smearing algorithm to be small for moderate to light bare quark masses. For a heavy bare quark mass we find a strong dependence on the number of smearing sweeps.