123705624
Generation of Entangled Multi-atom Dicke States in Cavity Quantum Electrodynamics
We propose a scheme to generate two-atom maximally entangled state in cavity quantum electrodynamics (QED). The scheme can be extended to generation of entangled multi-atom Dicke states if we control the interaction time of atoms with cavity modes. We use adiabatically state evolution under large atom-cavity detuning, so the scheme is insensitive to atomic spontaneous decay. The influence of cavity decay on fidelity and success probability is discussed.
119181778
Saving fourth generation and baryon number by living long
Abstract Recent studies of precision electroweak observables have led to the conclusion that a fourth generation is highly constrained. However, we point out that a long-lived fourth generation can reopen a large portion of the parameter space. In addition, it preserves baryon and lepton asymmetries against sphaleron erasure even if B − L = 0 . It opens up the possibility of exact B − L symmetry and hence Dirac neutrinos. The fourth generation can be observed at the LHC with unique signatures of long-lived particles in the near future.
119233408
General composite Higgs models
A bstractWe construct a general class of pseudo-Goldstone composite Higgs models, within the minimal SO(5)/SO(4) coset structure, that are not necessarily of moose-type. We characterize the main properties these models should have in order to give rise to a Higgs mass around 125 GeV. We assume the existence of relatively light and weakly coupled spin 1 and 1/2 resonances. In absence of a symmetry principle, we introduce the Minimal Higgs Potential (MHP) hypothesis: the Higgs potential is assumed to be one-loop dominated by the SM fields and the above resonances, with a contribution that is made calculable by imposing suitable generalizations of the first and second Weinberg sum rules. We show that a 125 GeV Higgs requires light, often sub-TeV, fermion resonances. Their presence can also be important for the models to successfully pass the electroweak precision tests. Interestingly enough, the latter can also be passed by models with a heavy Higgs around 320 GeV. The composite Higgs models of the moose-type considered in the literature can be seen as particular limits of our class of models.
118744156
Two jets and missing ET signature to determine the spins of new particles
We consider the spin determination of new colored particles in the missing energy plus jets channel at the early stage of the discovery. We use a three site moose model to describe the low energy Lagrangian of all same spin partner (LHT or UED like) models and check the gauge invariance of the amplitude. For the benchmark production and decay channel pp → U(R)U(R) → uuBHBH, in contrast to those in supersymmetric models, there are spin correlations which affect the polar and azimuthal angle distributions of the quarks from the heavy partner U(R) decay. We show such effects would be visible in the ETmiss/Meff distribution and the reconstructed azimuthal angle correlation using MAOS reconstruction.
119611795
Kaluza-Klein gluons as a diagnostic of warped models
We study the properties of g{sup 1}, the first excited state of the gluon in representative variants of the Randall-Sundrum (RS) model with the standard model (SM) fields in the bulk. We find that measurements of the coupling to light quarks (from the inclusive cross section for pp-->g{sup 1}-->t[overline t]), the coupling to bottom quarks (from the rate of pp-->g{sup 1}b), as well as the overall width can provide powerful discriminants between the models. In models with large brane kinetic terms, the g{sup 1} resonance can even potentially be discovered decaying into dijets against the large QCD background. We also derive bounds based on existing Tevatron searches for resonant t[overline t] production and find that they require M{sub g{sup 1}} > {approx} 950 GeV. In addition, we explore the pattern of interference between the g{sup 1} signal and the nonresonant SM background, defining an asymmetry parameter for the invariant mass distribution. The interference probes the relative signs of the couplings of the g{sup 1} to light quark pairs and to t[overline t], and thus provides an indication that the top is localized on the other side of the extra dimension from the light quarks, as is typical in the RSmore » framework.« less
118716263
A Revisit to Top Quark Forward-Backward Asymmetry
We analyze various models for the top quark forward-backward asymmetry ($A^t_{FB}$) at the Tevatron, using the latest CDF measurements on different $A^t_{FB}$s and the total cross section. The axigluon model in Ref. \cite{paul} has difficulties in explaining the large rapidity dependent asymmetry and mass dependent asymmetry simultaneously and the parameter space relevant to $A^t_{FB}$ is ruled out by the latest dijet search at ATLAS. In contrast to Ref. \cite{cp}, we demonstrate that the large parameter space in this model with a $U(1)_d$ flavor symemtry is not ruled out by flavor physics. The $t$-channel flavor-violating $Z^{\prime}$ \cite{hitoshi}, $W^{\prime}$\cite{waiyee} and diquark \cite{tim} models all have parameter regions that satisfy different $A_{FB}$ measurements within 1 $\sigma$. However, the heavy $Z^{\prime}$ model which can be marginally consistent with the total cross section is severely constrained by the Tevatron direct search of same-sign top quark pair. The diquark model suffers from too large total cross section and is difficult to fit the $t \bar{t}$ invariant mass distribution. The electroweak precision constraints on the $W'$ model based on $Z'$-$Z$ mixings is estimated and the result is rather weak ($m_{Z'} > 450$ GeV). Therefore, the heavy $W^{\prime}$ model seems to give the best fit for all the measurements. The $W^{\prime}$ model predicts the $t\bar{t}+j$ signal from $tW^{\prime}$ production and is 10%-50% of SM $t\bar{t}$ at the 7 TeV LHC. Such $t+j$ resonance can serve as the direct test of the $W^{\prime}$ model.
121375687
Behavior of thallium bromide conduction counters
Abstract A study at various temperatures has been made of approximately a dozen TlBr single crystals in order to find their properties as radiation induced conduction counters. Use of alpha particle sources showed whether holes or electrons were responsible for the observed behavior. Gamma ray studies showed rudimentary spectrometric performance whereas alpha particles usually resulted in peaks of approximately 25% fwhm. Long rise times were observed in some crystals and shorter rise times in others, the variability accounting for as much as a factor of 6. The energy required to produce a free electron-hole pair was observed to be 10.3 ± 2 eV. Breakdown phenomena were observed near room temperature and are described in the text.