118742346
Gaugino masses from gravitino at one loop
The N=1 supergravity coupled to chiral and Yang-Mills superfields is regarded as the ultraviolet theory of the supersymmetric Standard Model. The gravitino acquires a mass from the hidden sector and participate in mediating supersymmetry breaking to the visible sector. We consider the quantum effects of the gravitino and evaluate its contribution to the gaugino masses at one loop level, which turns out to be irrespective of the SM gauge couplings. Due to the universality of gravitino, its contribution to the gaugino masses can significantly modify the gaugino mass relations of other supersymmetry breaking mechanisms depending on the gravitino mass. For a given gaugino mass the gravitino mass cannot be arbitrarily large even when other supersymmetry breaking mechanisms are dominant.
119066417
A vector-like heavy quark in the littlest Higgs model
The littlest Higgs model contains a new vector-like heavy quark in the up sector. There are two interesting features of its existence. One is that it extends the 3 × 3 CKM matrix in the standard model to a 4 × 3 matrix and the other is that it allows Z-mediated flavor changing neutral currents at tree level in the up sector but not in the down sector. We examine a few of possible windows in which the Z-mediated flavor changing neutral currents in the littlest Higgs model can be tested.
119504141
Neutrinos in the Simplest Little Higgs Model
The simplest little Higgs model based on a SU(3) global symmetry contains a $SU(3)_{weak}$ triplet and a singlet per a generation in the lepton sector. A neutral component of the triplet and the singlet turn into a neutral vector-like $SU(2)_L$ singlet after electroweak symmetry breaking while the other neutral component of the triplet is the SM neutrino. At tree level, Yukawa couplings of the lepton sector not only allow the neutral vector-like lepton to couple to the SM neutrino, but also give them a Dirac mass. Majorana mass terms for the SM neutrinos and their partners arise at one loops, leading to neutrino flavor mixing in addition to neutrino-heavy neutral lepton mixing.
126168504
Neutrino Masses, Lepton Flavor Violations, and Flavor Changing Neutral Currents in the Composite Little Higgs Model
16040475
A composite little Higgs model
We describe a natural UV complete theory with a composite little Higgs. Below a TeV we have the minimal Standard Model with a light Higgs, and an extra neutral scalar. At the TeV scale there are additional scalars, gauge bosons, and vector-like charge 2/3 quarks, whose couplings to the Higgs greatly reduce the UV sensitivity of the Higgs potential. Stabilization of the Higgs mass squared parameter, without finetuning, occurs due to a softly broken shift symmetry — the Higgs is a pseudo Nambu-Goldstone boson. Above the 10 TeV scale the theory has new strongly coupled interactions. A perturbatively renormalizable UV completion, with softly broken supersymmetry at 10 TeV is explicitly worked out. Our theory contains new particles which are odd under an exact ``dark matter parity, (−1)(2S+3B+L). We argue that such a parity is likely to be a feature of many theories of new TeV scale physics. The lightest parity odd particle, or ``LPOP, is most likely a neutral fermion, and may make a good dark matter candidate, with similar experimental signatures to the neutralino of the MSSM. We give a general effective field theory analysis of the calculation of corrections to precision electroweak observables.
5280546
Constraints on R parity and B violating couplings in gauge-mediated supersymmetry breaking models
Abstract We consider the proton decay involving a light gravitino or axino in gauge-mediated supersymmetry breaking models to derive constraints on the R parity and baryon number violating Yukawa couplings. Bounds on all nine coupling constants are obtained by considering the decay amplitudes at one-loop order.
16017829
Chemical abundances of three metal-poor globular clusters (ngc 6287, ngc 6293, and ngc 6541) in the inner halo
We present a chemical abundance study of three inner old halo clusters, NGC 6287, 6293, and 6541, finding [Fe/H] = -2.01 ± 0.05, -1.99 ± 0.02, and -1.76 ± 0.02 (internal), respectively, and our metallicity measurements are in good agreement with previous estimates. We also present the radial velocity measurements of the clusters. Our radial velocity measurements for NGC 6293 and NGC 6541 are in good agreement with previous measurements; however, our radial velocity measurement for NGC 6287 is almost 80 km s-1 larger than the previous measurement. The mean α-element abundances of our program clusters are in good agreement with other globular clusters, confirming previous results. However, the individual α-elements appear to follow different trends. The silicon abundances of the inner halo clusters appear to be enhanced, and the titanium abundances appear to be depleted compared to the intermediate halo clusters. Our results also appear to oppose to those of metal-rich bulge giants studied by McWilliam & Rich, who found that bulge giants are titanium-enhanced and silicon-deficient. In particular, [Si/Ti] ratios appear to be related to Galactocentric distances, in the sense that [Si/Ti] ratios decrease with Galactocentric distance. We propose that contributions from different masses of the Type II supernovae progenitors that enriched proto–globular cluster clouds' elemental abundances and the different initial physical environments surrounding the proto–globular clusters clouds are responsible for this gradient in [Si/Ti] ratios versus Galactocentric distances of the "old halo" globular clusters. On the other hand, our program clusters' enhanced s-process elemental abundances suggest that the formation timescale of our program clusters might be as short as a few times 108 yr after the star formation is initiated in the Galaxy's central regions, if the s-process site is intermediate-mass asymptotic giant branch stars.
118555774
Radiative corrections to scalar masses and mixing in a scale invariant two Higgs doublet model
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 HSM, we obtain rather strict constraints on the mass spectrum of the heavy Higgs sector of the SI-2HDM. In particular, if MHSM 125 GeV, the SI-2HDM strongly favors scenarios in which at least one of the nonstandard neutral Higgs bosons has a mass close to 400 GeV and is generically degenerate with the charged Higgs boson, whilst the third neutral Higgs scalar is lighter than 500 GeV.
40146055
Measurement of forward-backward asymmetry and Wilson coefficients in B --> K*l+l-.
We report the first measurement of the forward-backward asymmetry and the ratios of Wilson coefficients and in A9/A7 and A10/A7 in B --> K*l+l-, where l represents an electron or a muon. We find evidence for the forward-backward asymmetry with a significance of 3.4sigma. The results are obtained from a data sample containing 386 x 10(6) BB pairs that were collected on the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
119250984
Mass dependent top forward backward asymmetry in the effective Lagrangian approach: Addendum to `Model independent analysis of the forward-backward asymmetry of top quark production at the Tevatron'
Abstract Recently the CDF and the D0 Collaborations presented the data on the top forward–backward (FB) asymmetry A FB as functions of M t t ¯ and Δ y ≡ y t − y t ¯ . We study these observables in the effective Lagrangian approach with dimension-6 q q ¯ t t ¯ contact interactions, and compare with the CDF and D0 data. When we stay within the validity region of the effective Lagrangian approach, the mass dependent top FB asymmetry turns out to be smaller than the CDF data, more than 2- σ away. If this discrepancy remains in the future data with better statistics, it would imply that the effective Lagrangian approach is not adequate for the top FB asymmetry, and a new physics scale around a few hundred GeV in the t - or u -channel may be responsible for the observed top FB asymmetry.