Search results for "Color"
showing 10 items of 2721 documents
Light composite Higgs and precision electroweak measurements on the Z resonance: An update
2005
We update our analysis of technicolour theories with techniquarks in higher dimensional representations of the technicolour gauge group in the light of the new electroweak precision data on the Z resonance.
extended MSSM
2012
We investigate the perturbative regime of the Minimal Supersymmetric Con- formal Technicolor and show that it allows for a stable vacuum correctly breaking the electroweak symmetry. We nd that the particle spectrum is richer than the MSSM one since it features several new particles stemming out from the new N = 4 sector of the theory. The parameter space of the new theory is reduced imposing naturalness of the cou- plings and soft supersymmetry breaking masses, perturbativity of the model at the EW scale as well as phenomenological constraints. By studying the RGEs at two loops we nd that the Yukawa couplings of the heavy fermionic states
Discriminating between technicolor and warped extra dimensional model viapp→ZZchannel
2009
We explore the possibility to discriminate between certain strongly coupled technicolor (TC) models and warped extra dimensional models where the standard model fields are propagating in the extra dimension. We consider a generic QCD-like TC model with running coupling as well as two TC models with walking dynamics. We argue that, due to the different production mechanisms for the lowest-lying composite tensor state in these TC theories compared to the first Kaluza-Klein graviton mode of the warped extra dimensional case, it is possible to distinguish between these models based on the angular analysis of the reconstructed longitudinal $Z$ bosons in the $pp\ensuremath{\rightarrow}ZZ\ensurema…
Naturality, unification and dark matter
2010
We consider a model where electroweak symmetry breaking is driven by technicolor dynamics with minimal particle content required for walking coupling and saturation of global anomalies. Furthermore, the model features three additional Weyl fermions singlet under technicolor interactions, two of which provide for a one-loop unification of the standard model gauge couplings. Among these extra matter fields exists a possible candidate for weakly interacting dark matter. We evaluate the relic densities and find that they are sufficient to explain the cosmological observations and avoid the experimental limits from earth-based searches. Hence, we establish a nonsupersymmetric framework where hie…
Monochromatic neutrino beams
2005
In the last few years spectacular results have been achieved with the demonstration of non vanishing neutrino masses and flavour mixing. The ultimate goal is the understanding of the origin of these properties from new physics. In this road, the last unknown mixing [U-e3] must be determined. If it is proved to be non-zero, the possibility is open for Charge Conjugation-Parity (CP) violation in the lepton sector. This will require precision experiments with a very intense neutrino source. Here a novel method to create a monochromatic neutrino beam, an old dream for neutrino physics, is proposed based on the recent discovery of nuclei that decay fast through electron capture. Such nuclei will…
Radiative Corrections to Scalar Masses and Mixing in a Scale Invariant Two Higgs Doublet Model
2012
We study the Higgs-boson mass spectrum of a classical scale-invariant realization of the two-Higgs-doublet model (SI-2HDM). The classical scale symmetry of the theory is explicitly broken by quantum loop effects due to gauge interactions, Higgs self-couplings and top-quark Yukawa couplings. We determine the allowed parameter space compatible with perturbative unitarity and electroweak precision data. Taking into account the LEP and the recent LHC exclusion limits on a Standard-Model-like Higgs boson H_SM, we obtain rather strict constraints on the mass spectrum of the heavy Higgs sector of the SI-2HDM. In particular, if M_{H_SM} \sim 125 GeV, the SI-2HDM strongly favours scenarios, in which…
PREDICTIONS FOR p+PbCOLLISIONS AT $\sqrt{s_{_{\it NN}}} = 5$
2013
Predictions for charged hadron, identified light hadron, quarkonium, photon, jet and gauge bosons in p+Pb collisions at $\sqrt{s_{_{\it NN}}} = 5\, {\rm TeV}$ are compiled and compared. When test run data are available, they are compared to the model predictions.
Dynamical Symmetry Breaking in Warped Compactifications
2001
We study dynamical electroweak symmetry breaking in the Randall-Sundrum scenario. We show that one extra dimension is enough to give the correct pattern of electroweak symmetry breaking in a simple model with gauge bosons and the right-handed top quark in the bulk. The top quark mass is also in agreement with experiment. Furthermore, we propose an extended scenario with all Standard Model gauge bosons and fermions propagating in the bulk, which naturally accommodates the fermion mass hierarchies. No new fields or interactions beyond the observed in the Standard Model are required.
Unnatural origin of fermion masses for technicolor
2009
We explore the scenario in which the breaking of the electroweak symmetry is due to the simultaneous presence and interplay of a dynamical sector and an unnatural elementary Higgs. We introduce a low energy effective Lagrangian and constrain the various couplings via direct search limits and electroweak and flavor precision tests. We find that the model we study is a viable model of dynamical breaking of the electroweak symmetry.
Centrality dependence of the pseudorapidity density distribution for charged particles in Pb–Pb collisions at sNN=2.76 TeV
2017
We present the charged-particle pseudorapidity density in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\,\mathrm{Te\kern-.25exV}$ in centrality classes measured by ALICE. The measurement covers a wide pseudorapidity range from $-3.5$ to $5$, which is sufficient for reliable estimates of the total number of charged particles produced in the collisions. For the most central (0-5%) collisions we find $21\,400\pm 1\,300$ while for the most peripheral (80-90%) we find $230\pm 38$. This corresponds to an increase of $(27\pm4)\%$ over the results at $\sqrt{s_{\mathrm{NN}}}=2.76\,\mathrm{Te\kern-.25exV}$ previously reported by ALICE. The energy dependence of the total number of charged particles…