119498170
Non-zeta knots in the renormalization of the Wess-Zumino model?
Abstract We solve the Schwinger Dyson equations of the O ( N ) symmetric Wess-Zumino model at O (1/ N 3 ) at the non-trivial fixed point of the d -dimensional β -function and deduce a critical exponent for the wave function renormalization at this order. By developing the ϵ -expansion of the result, which agrees with known perturbation theory, we examine the distribution of transcendental coefficients and show that only the Riemann ζ series arises at this order in 1/ N . Unlike the analogous calculation at the same order in the bosonic O ( N ) φ 4 -theory non-zeta transcendentals, associated with for example the (3,4)-torus knot, cancel.
118589050
Avoiding Death by Vacuum
The two-Higgs doublet model (2HDM) can have two electroweak breaking, CP-conserving, minima. The possibility arises that the minimum which corresponds to the known elementary particle spectrum is metastable, a possibility we call the panic vacuum. We present analytical bounds on the parameters of the softly broken Peccei-Quinn 2HDM which are necessary and sufficient conditions to avoid this possibility. We also show that, for this particular model, the current LHC data already tell us that we are necessarily in the global minimum of the theory, regardless of any cosmological considerations about the lifetime of the false vacua.
118483060
Can we build a sensible theory with broken charge and colour symmetries
Charge and colour symmetries are broken using the vevs of scalar fields, but it is shown the theory possesses a photon-like massless particle and electroweak interactions almost identical to those of the Standard Model. We consider experimental signatures of this theory.
119180593
Metastability bounds on the two Higgs doublet model
A bstractIn the two Higgs doublet model, there is the possibility that the vacuum where the universe resides in is metastable. We present the tree-level bounds on the scalar potential parameters which have to be obeyed to prevent that situation. Analytical expressions for those bounds are shown for the most used potential, that with a softly broken Z2 symmetry. The impact of those bounds on the model’s phenomenology is discussed in detail, as well as the importance of the current LHC results in determining whether the vacuum we live in is or is not stable. We demonstrate how the vacuum stability bounds can be obtained for the most generic CP-conserving potential, and provide a simple method to implement them.
18964730
Probing wrong-sign Yukawa couplings at the LHC and a future linear collider
We consider the two-Higgs-doublet model as a framework in which to evaluate the viability of scenarios in which the sign of the coupling of the observed Higgs boson to down-type fermions (in particular, b-quark pairs) is opposite to that of the Standard Model (SM), while at the same time all other tree-level couplings are close to the SM values. We show that, whereas such a scenario is consistent with current LHC observations, both future running at the LHC and a future e +e − linear collider could determine the sign of the Higgs coupling to b-quark pairs. Discrimination is possible for two reasons. First, the interference between the b-quark and the t-quark loop contributions to the ggh coupling changes sign. Second, the charged-Higgs loop contribution to the γγh coupling is large and fairly constant up to the largest charged-Higgs mass allowed by tree-level unitarity bounds when the b-quark Yukawa coupling has the opposite sign from that of the SM (the change in sign of the interference terms between the b-quark loop and the W and t loops having negligible impact).
119493491
One-loop stau masses in the effective potential approach
We calculate the one-loop contributions to the tau slepton masses in the Minimal Supersymmetric Standard Model in the effective potential approach. For the majority of parameter space under study, those corrections are shown to elevate the value of the lightest stau mass.
12363895
A slight excess of large-scale power from moments of the peculiar velocity field
ABSTRACT The peculiar motions of galaxies can be used to infer the distribution of matter in theUniverse.It has recently been shown that measurementsof the peculiar velocityﬁeld indicatesan anomalously high bulk ﬂow of galaxies in our local volume. In this paper we ﬁnd theimplications of the high bulk ﬂow for the power spectrum of de nsity ﬂuctuations. We ﬁndthat analyzing only the dipole moment of the velocity ﬁeld yi elds an average power spectrumamplitude which is indeed much higher than the ΛCDM value. However, by also includingshear and octupole moments of the velocity ﬁeld, and margina lizing over possible values forthe growth rate, an average power spectrum amplitude which is consistent with ΛCDM isrecovered. We attempt to infer the shape of the matter power spectrum from moments of thevelocity ﬁeld, and ﬁnd a slight excess of power on scales ∼1h −1 Gpc.Key words: cosmology: large scale structure of the universe – cosmology: observation –cosmology: theory – galaxies: kinematics and dynamics – gal axies: statistics
16319433
The trispectrum of the cosmic microwave background on subdegree angular scales: an analysis of the BOOMERanG data
The trispectrum of the cosmic microwave background can be used to assess the level of non-Gaussianity on cosmological scales. It probes the fourth-order moment, as a function of angular scale, of the probability distribution function of fluctuations and has been shown to be sensitive to primordial non-Gaussianity, secondary anisotropies (such as the Ostriker–Vishniac effect) and systematic effects (such as astrophysical foregrounds). In this paper we develop a formalism for estimating the trispectrum from high-resolution sky maps that incorporates the impact of finite sky coverage. This leads to a series of operations applied to the data set to minimize the effects of contamination due to the Gaussian component and correlations between estimates at different scales. To illustrate the effect of the estimation process, we apply our procedure to the BOOMERanG data set and show that it is consistent with Gaussianity. This work presents the first estimation of the cosmic microwave background trispectrum on subdegree scales.
36776076
A few cosmological implications of tensor nonlocalities
We consider nonlocal gravity theories that include tensor nonlocalities. We show that in the cosmological context, the tensor nonlocalities, unlike scalar ones, generically give rise to growing modes. An explicit example with quadratic curvature terms is studied in detail. Possible consequences for recent nonlocal cosmological models proposed in the literature are also discussed.
14262164
Mass for Plasma Photons from Gauge Symmetry Breaking
We derive the effective masses for photons in unmagnetized plasma waves using a quantum field theory with two vector fields (gauge fields). In order to properly define the quantum field degrees of freedom we re-derive the classical wave equations on light-front gauge. This is needed because the usual scalar potential of electromagnetism is, in quantum field theory, not a physical degree of freedom that renders negative energy eigenstates. We also consider a background local fluid metric that allows for a covariant treatment of the problem. The different masses for the longitudinal (plasmon) and transverse photons are in our framework due to the local fluid metric. We apply the mechanism of mass generation by gauge symmetry breaking recently proposed by the authors by giving a non-trivial vacuum-expectation-value to the second vector field (gauge field). The Debye length λ D is interpreted as an effective compactification length and we compute an explicit solution for the large gauge transformations that correspond to the specific mass eigenvalues derived here. Using an usual quantum field theory canonical quantization we obtain the usual results in the literature. Although none of these ingredients are new to physicist, as far as the authors are aware it is the first time that such constructions are applied to Plasma Physics. Also we give a physical interpretation (and realization) for the second vector field in terms of the plasma background in terms of known physical phenomena.
119211611
A Locally Anisotropic Metric for Matter in an Expanding Universe: I. The Ansatz and the Modified Newton Law
It is suggested a metric ansatz to describe local matter in an expanding universe, hence interpolating between the Schwarzschild metric at small spatial scales and the FLRW metric at large spatial scales. This is acomplished maintaining space-time free of singularities except for the Schwarzschild mass pole at the origin as opposed to metrics already considered in the literature with the same purpose, namely the McVittie metric. The modified Newton law is analyzed and the static orbit solutions computed. It is concluded that the effects of expantion in the solar system are negligible, however depending on the metric parameter value, at galactic scales there is a significant deviation from the General Relativity Newton law which may contribute to dark matter effects allowing for a flattening of galaxy rotation curves.