122967569
On symmetry breaking in a generalized gravity induced superpotential
The Nanopoulos‐Srednicki superpotential is generalized to include terms proportional to the n‐th power of the adjoint 24‐representation A of SU(5) assumed to be induced by gravity. It has been shown that the symmetry breaking scheme SU(5) → SU(3)×SU(2)×U(1) stays unaltered by the addition of such terms, if we subject the parameters to some suitable constraints.
117848193
Symmetry behavior of a higher-power self-interacting scalar field at finite temperature
We have generalized the finite-temperature treatment of the scalar field of Dolan and Jackiw up to the one-loop approximation by adding an extra term which is proportional to the sixth power of the field. The inclusion of such a term makes the theory nonrenormalizable. However, we have carried out, parallel to the renormalizable theory, a subtraction method which we call ''restricted renormalization'' in order to study the effect of the inclusion of this term. The critical temperature in the theory does not depend on the coupling constant kappa associated with the phi/sup 4/ term in the interaction. Also, the theory even at the phi/sup 4/ level depends on an integral parameter n, if we consider the critical-temperature equation as a complex equation. We are then forced to introduce different fields depending on the parameter n. However, not all n-values are allowed. Up to the approximation considered, the n-values have to be greater than 1.
121785099
U and V sectors in the Bronzan‐Lee model
The Lehmann‐Symanzik‐Zimmermann (LSZ) formalism is used in the Bronzan‐Lee model to investigate the scattering processes in the lowest sectors. In this model, there are three heavy recoilless particles U, V, and N interacting with a θ particle. The processes allowed are U⇄Vθ and V⇄Nθ. In U and V sectors of this model all τ functions have been calculated, and relevant scattering and production amplitudes are evaluated. The mass, wavefunction, and vertex function renormalization constants have been found and they agree with the results previously obtained by Bronzan and later also by Liossatos.
117425048
Callan-Symanzik equation in Bronzan-Lee model
119098723
Influence of collapsing matter on the enveloping expanding universe
Using a collapsing matter model at the center of an expanding universe as described by Weinberg we assume a special type of generated pressure. This pressure transmits into the surrounding expanding universe. Under certain restriction the ensuing hubble parameter is positive. The deacceleration parameter fluctuates with time, indicating that the universe accelerates for certain time and decelerates for other time intervals.
125036010
Symmetry breaking in gravity induced superpotential
La partie du superpotentiel de Nanopoulos-Srednicki qui donne une rupture de symetrie desiree est generalisee pour inclure des termes proportionnels a TrA 4 et (TrA 2 ) 2
118682766
SUSY signals with small and large trilinear couplings at the LHC 7 TeV runs and neutralino dark matter
We propose the signal $1b+1l+N_j+\etslash$ along with appropriate selection criteria for the LHC 7 TeV run, where the number of jets $(N_j)$ is $\ge$ 2 or 4. These signals can complement the canonical $Jets + \etslash$ signature since they are sensitive to the trilinear soft breaking parameter $(A_0)$ and low values of the parameter tan$\beta$ in the minimal supergravity (mSUGRA) model. A large region of this mSUGRA parameter space within the reach of the ongoing experiments at the LHC is disfavoured by the bound on the lightest Higgs boson mass ($m_h \ge 114.4 $ GeV) unless $A_0$ has moderate to large negative values. Interestingly this parameter space with $A_0 \ne 0$ is also consistent with the observed dark matter relic density. A natural consequence of large $A_0$ is the existence of a light top squark ($\lstop$). The proposed signals primarily stem from direct $\lstop \lstop^*$ production and/or $\tilde g \ra \tilde t_{1} t $, if all squark-gluino events are considered. A thorough analysis of the signals and the corresponding backgrounds are presented using the event generator Pythia. We finally compare the signal size for $A_0 = 0$ and $A_0 \ne 0$.
119115306
Neutralino dark matter confronted by the LHC constraints on electroweak SUSY signals
A bstractThe supersymmetric particles (sparticles) belonging exclusively to the electroweak sector of the minimal supersymmetric standard model (MSSM) may hold the key to the observed dark matter relic density in the universe even if all strongly interacting sparticles are very heavy. The importance of the light EW sparticles in DM physics and in producing spectacular collider signals is emphasized. It is shown that even the preliminary data on the direct searches of these sparticles at the LHC, significantly constrain the parameter space of the MSSM compatible with the observed relic density and provide useful hints about the future search prospects. If in addition to the electroweak sparticles the gluinos are also within the reach of the LHC experiments, then the gluino mass limits in the light slepton scenario obtained via the canonical jets + / channel may be relaxed by as much as 25 % compared to the existing limits. But the corresponding same sign dilepton (SSD) + jets + / signal will yield enhanced limits competitive with the strongest limits currently available. This is illustrated with the help of benchmark scenarios at the generator level using PYTHIA. If the gluinos are just beyond the current reach of the LHC, then the generic n-lepton + m-jets + missing energy signal may discriminate between different DM producing mechanisms by comparing the signals corresponding to different values of n. This is illustrated by simulating the signals for n = 0 and n = 2 (the SSD signal).
59057471
Many faces of low mass neutralino dark matter in the unconstrained MSSM, LHC data and new signals
A bstractIf all strongly interacting sparticles (the squarks and the gluinos) in an un- constrained minimal supersymmetric standard model (MSSM) are heavier than the corre- sponding mass lower limits in the minimal supergravity (mSUGRA) model, obtained by the current LHC experiments, then the existing data allow a variety of electroweak (EW) sectors with light sparticles yielding dark matter (DM) relic density allowed by the WMAP data. Some of the sparticles may lie just above the existing lower bounds from LEP and lead to many novel DM producing mechanisms not common in mSUGRA. This is illustrated by revisiting the above squark-gluino mass limits obtained by the ATLAS Collaboration, with an unconstrained EW sector with masses not correlated with the strong sector. Using their selection criteria and the corresponding cross section limits, we find at the generator level using Pythia, that the changes in the mass limits, if any, are by at most 10-12 % in most scenarios. In some cases, however, the relaxation of the gluino mass limits are larger (≈ 20 %). If a subset of the strongly interacting sparticles in an unconstrained MSSM are within the reach of the LHC, then signals sensitive to the EW sector may be obtained. This is illustrated by simulating the bljT , l = e and μ, and bτ jT signals in i) the light stop scenario and ii) the light stop-gluino scenario with various light EW sectors allowedby the WMAP data. Some of the more general models may be realized with non-universal scalar and gaugino masses.