119316975
GMSB at a stable vacuum and MSSM without exotics from heterotic string
Abstract We show that it is possible to introduce the confining hidden sector gauge group SU ( 5 ) ′ with the chiral matter 10 0 ′ plus 5 ¯ 0 ′ , which are neutral under the standard model gauge group, toward a gauge mediated supersymmetry breaking (GMSB) in a Z 12 − I orbifold compactification of E 8 × E 8 ′ heterotic string. Three families of MSSM result without exotics. We also find a desirable matter parity P (or R-parity) assignment. We note that this model contains the spectrum of the Lee–Weinberg model which has a nice solution of the μ problem.
15739165
SO(10)-like Superstring Standard Model with R-parity from the Heterotic String
We construct a supersymmetric standard model in the context of the Z_{12-I} orbifold compactification of the E_8 x E_8' heterotic string theory. The gauge group is SU(3)_c x SU(2)_L x U(1)_Y x U(1)^4 x [SO(10) x U(1)^3]' with sin^2\theta_W = 3/8. We obtain three families of SO(10) spinor-like chiral matter states, and Higgs doublets. All other extra states are exactly vector-like under the standard model gauge symmetry. There are numerous standard model singlets, many of which get VEVs such that only the standard model gauge symmetry survives and desired Yukawa couplings can be generated at lower energies. In particular, all vector-like exotic states achieve superheavy masses and the R-parity can be preserved.
13291931
Hidden sector gaugino condensation and the model independent axion
Abstract In the effective field theory framework, we consider the effect of supersymmetry breaking via gaugino condensation and supergravity in the hidden sector gauge group on the hidden sector vacuum angle θ h . The θ h parameter dependence of the potential yields phenomenologically acceptable invisible axion solutions if the U (1) R symmetry is broken down to a discrete subgroup Z N with N ≥3 ( N =4 is marginal). Anomalous U(1) superstring models are good candidates for this invisible axion resolution of the strong CP puzzle.
56138229
Gauge CP symmetry, wormhole effects, and strong CP problem
The recent observation of four dimensional CP as a discrete gauge symmetry in 8k + 1, 8k + 2 and 8k + 3 Minkowski dimensions calls for a serious reconsid­ eration of various solutions of the strong CP problem. In these possible higher dimensions, the relevant one is a ten dimensional string theory in which a possi­ bility of light fermions exists. We point out that the model independent axion in the heterotic string theory solves the strong CP problem. We also point out that the wormhole effects to low energy global and discrete symmetries are negligible. .. " JIf',!\f':-,',f,' ,. aJ , I <\ " ; \ ,k fL .::LJ.i2" ('If"T 11 . J' ., __ ".1: 1992 11!llllnrB1i1111111 -SAlUT? -·9/ --..5~ o 11bO 0011852 5 .................. • The recent observation of four dimensional CP as a discrete gauge symmetry in 8k +1, 8k +2 and 8k +3 Minkowski dimensions [1] calls for a new understand­ ing on the weak CP violation and the strong CP invariance. Among the possible higher dimensions, the relevant one is 10 because there exists a phenomenologi­ cally viable heterotic string theory [2]. The other extra dimensions not utilized by nature are only of academic interest. In the heterotic string theory, it has been known that the four dimensional CP must be a gauge symmetry since the theory does not have any discrete symmetry except Es +-+ E~ [3]. The discrete symmetry Es +-+ E~ cannot contain the four dimensional CP of light fermions and anti-fermions since they are singlets of E~. In string theories, therefore, the required weak CP violation must arise through spontaneous breaking [4]. The Kobayashi-Maskawa weak CP phase which looks like a hard CP violation at low energy may in fact have descended down from string scale physics through spon­ taneous breaking mechanism [5]. Inflation after the spontaneous CP violation might have removed the dangerous domain walls from our observable universe. The 'calculability' solutions of the Nelson-Barr type [6] to the strong CP problem have a rationale (8QCD = 0) in higher dimensions due to CP as a discrete gauge symmetry of Lagrangian. However, there are two questions to be cleared regarding the strong CP prob­ lem. Firstly, should we consider extra dimensions? Second, what is the effect of gravity on the four dimensional low energy symmetries? In this Letter, we consider both of these questions from Planck scale physics. Regarding the first question, an extension of spatial dimensions should not be in contradiction with low energy physics. Phenomenologically, there is no reason to extend the spatial dimensions. However, one may try to include more spatial dimensions to solve theoretical problems of the standard model. So in consideration of dis'crete and global symmetries in higher dimensions, at present the ten dimensional heterotic string is the only one to be considered. Thus, let us consider the (} parameter in the heterotic string theory in ten dimension. The heterotic string has a model-independent axion aMI [7] whose decay constant is
16580747
String Compactification and Unification of Forces
I review our recent attempts toward obtaining the MSSM from string orbifold compactification. The required constraints are the existence of three families and R parity, vectorlike exotics, one pair of Higgs doublets, and the SU(5)′ hidden sector for dynamical breaking of SUSY toward a GMSB scenario. We also comment on the threshold correction which are influenced by a power law evolution of gauge couplings through the KK radius in non‐prime orbifolds and can be used to fit the couplings.
119883211
Conflicts between B-violating phenomena in supergravity models
Abstract We show that there is an incompatibility between matter stability and cosmological baryon production in standard N = 1 supergravity models. This discrepancy emerges from the bound on the reheating temperature T rh ⩽ 10 10 GeV which comes from the restriction on the gravitino decay after inflation. Some weird possibilities to bypass the controversy are also analyzed.
17558967
Accelerated recombination and primordial baryonic clouds: the recent CMB and SDSS data constraint, and the constraint forecast for the PLANCK surveyor
We have constrained the extended (delayed and accelerated) models of hydrogen recombination, by investigating associated changes of the position and the width of the last scattering surface. Using the recent CMB and SDSS data, we find that the recent data constraints favor the accelerated recombination model, though the other models (standard, delayed recombination) are not ruled out at 1-σ confidence level. If the accelerated recombination had actually occurred in our early Universe, baryonic clustering on small-scales is likely to be the cause of it. By comparing the ionization history of baryonic cloud models with that of the best-fit accelerated recombination model, we find that some portion of our early Universe has baryonic underdensity. We have made the forecast on the PLANCK data constraint, which shows that we will be able to rule out the standard or delayed recombination models, if the recombination in our early Universe had proceeded with ǫα ∼ −0.01 or lower, and residual foregrounds and systematic effects are negligible. PACS numbers: 98.70.Vc, 98.80.Bp, 98.80.-k, 98.80.Es Accelerated recombination and primordial baryonic clouds 2
53580211
The higgsino–singlino world at the large hadron collider
We consider light higgsinos and singlinos in the next-to-minimal supersymmetric standard model at the large hadron collider. We assume that the singlino is the lightest supersymmetric particle and that the higgsino is the next-to-lightest supersymmetric particle with the remaining supersymmetric particles in the multi-TeV range. This scenario, which is motivated by the flavor and CP issues, provides a phenomenologically viable dark matter candidate and improved electroweak fit consistent with the measured Higgs mass. Here, the higgsinos decay into on (off)-shell gauge boson and the singlino. We consider the leptonic decay modes and the resulting signature is three isolated leptons and missing transverse energy which is known as the trilepton signal. We simulate the signal and the Standard Model backgrounds and present the exclusion region in the higgsino–singlino mass plane at the large hadron collider at $$\sqrt{s}=14$$s=14 TeV for an integrated luminosity of 300 fb$$^{-1}$$-1.
118704767
First LHC Constraints on Neutralinos
Abstract The ATLAS and CMS Collaborations have recently reported tantalizing hints of the existence of a 125 GeV Higgs-like particle, whose couplings appear to match well the Standard Model (SM) expectations. In this work, we study implications of this observation for the neutralino sector of supersymmetric models, assuming that the Higgs signal gets confirmed. In general, the Higgs decay into neutralinos can be one of its dominant decay channels. Since a large invisible Higgs decay branching ratio would be in conflict with the data, this possibility is now constrained. In particular, we find that most of the region μ 170 GeV , M 1 70 GeV at tan β ∼ 10 and μ 120 GeV , M 1 70 GeV at tan β ∼ 40 is disfavored.
54918406
Light stop searches at the LHC with monojet events
We consider light top squarks (stops) in the minimal supersymmetric Standard Model at the Large Hadron Collider. Here, we assume that the lightest neutralino is the lightest supersymmetric particle (LSP) and the lighter stop is the next-to-LSP. Stop pair production is difficult to probe at the Large Hadron Collider for small stop-LSP mass splitting. It has been shown previously that even in this case stop detection is possible if one considers stop pair production in association with one hard jet. We reconsider this supersymmetric monojet signature and go beyond previous works by including the full Standard Model background and optimizing the cuts, working at the hadron level and including detector effects. As a result, a larger portion of the stop-LSP mass plane becomes accessible to monojet searches.
118455901
CMB data constraint on self-annihilation of dark matter particles
Recently, self‐annihilation of dark matter particles is proposed to explain the “WMAP Haze” and excess of energetic positrons and electrons in ATIC and PAMELA results. If self‐annihilation of dark matter occurs around the recombination of cosmic plasma, energy release from self‐annihilation of dark matter delays the recombination, and hence affects CMB anisotropy. By using the recent CMB data, we have investigated the self‐annihilation of dark matter particles. In this investigation, we do not find statistically significant evidence, and impose an upper bound on 〈σν〉/mϰ.The upcoming data from Planck surveyor and the Fermi Gamma‐ray telescope will allow us to break some of parameter degeneracy and improve constraints on self‐annihilation of dark matter particles.