119122873
Longitudinal top polarization as a probe of a possible origin of forward–backward asymmetry of the top quark at the Tevatron
Abstract If the forward–backward (FB) asymmetry of top quark ( A FB ) observed at the Tevatron deviates from the SM prediction, there must be P -violating interactions in q q ¯ → t t ¯ . This new interaction will necessarily affect the top spin polarization. In this Letter, we perform a model independent analysis on the longitudinal (anti)top polarization ( P L and P ¯ L ) using an effective lagrangian with dim-6 four-quark operators relevant for q q ¯ → t t ¯ , and show that the P -odd observable corresponding to the polarization difference ( P L − P ¯ L ) gives important informations on the chiral structures of new physics that might be relevant to the A FB .
119107944
Singlino-driven electroweak baryogenesis in the next-to-MSSM
Abstract We explore a new possibility of electroweak baryogenesis in the next-to-minimal supersymmetric standard model. In this model, a strong first-order electroweak phase transition can be achieved due to the additional singlet Higgs field. The new impact of its superpartner (singlino) on the baryon asymmetry is investigated by employing the closed-time-path formalism. We find that the CP violating source term fueled by the singlino could be large enough to generate the observed baryon asymmetry of the Universe without any conflicts with the current constraints from the non-observation of the thallium, neutron and mercury electric dipole moments.
43894133
A geometric approach to CP violation: applications to the MCPMFV SUSY model
We analyze the constraints imposed by experimental upper limits on electric dipole moments (EDMs) within the Maximally CP -and Minimally Flavour-Violating (MCPMFV) version of the MSSM. Since the MCPMFV scenario has 6 non-standard CP -violating phases, in addition to the CP -odd QCD vacuum phase θQCD, cancellations may occur among the CP -violating contributions to the three measured EDMs, those of 205Tl, the neutron and 199Hg, leaving open the possibility of relatively large values of the other CP -violating observables. We develop a novel geometric method that uses the small-phase approximation as a starting point, takes the existing EDM constraints into account, and enables us to find maximal values of other CP -violating observables, such as the EDMs of the Deuteron and muon, the CP -violating asymmetry in b→sγ decay, and the B s mixing phase. We apply this geometric method to provide upper limits on these observables within specific benchmark supersymmetric scenarios, including extensions that allow for a non-zero θQCD.
121878109
Proton decay with a light gravitino or axino
We consider proton decay in supersymmetric models with a gravitino or axino lighter than the proton. This consideration leads to a stringent limit on the R-parity and B-violating Yukawa coupling of the superpotential operator U{sub i}{sup c}D{sub j}{sup c}D{sub k}{sup c} as {lambda}{sub 112}{sup {double_prime}}{le}10{sup {minus}15}(m{sub 3/2}/eV) for a light gravitino, and {lambda}{sub 112}{sup {double_prime}}{le}10{sup {minus}15}(F{sub a}/10{sup 10} GeV) for a light Dine-Fischler-Srednicki-Zhitnitskii axino. For the hadronic axino, the constraint is weakened by a factor of 10{sup 3}. {copyright} {ital 1997} {ital The American Physical Society}
1562637
Remarks on the upper bounds on the Higgs boson mass from triviality.
We study the effects of the one-loop matching conditions on Higgs boson and top quark masses on the triviality bounds on the Higgs boson mass using {beta}{sub {lambda}} with corrected two-loop coefficients. We obtain quite higher results than previous ones and observe that the triviality bounds are not nearly influenced by varying the top quark mass over the range measured at CDF and D0. The effects of typographical errors in {beta}{sub {lambda}}{sup (2)} and the one-loop matching condition on the top quark mass are negligible. We estimate the size of the effects on the triviality bounds from the one-loop matching condition on the Higgs boson mass. {copyright} {ital 1996 The American Physical Society.}
3289948
Flavour geometry and effective Yukawa couplings in the MSSM
We present a new geometric approach to the flavour decomposition of an arbitrary soft supersymmetry-breaking sector in the MSSM. Our approach is based on the geometry that results from the quark and lepton Yukawa couplings, and enables us to derive the necessary and sufficient conditions for a linearly-independent basis of matrices related to the completeness of the internal [SU(3)⊗U(1)]5 flavour space. In a second step, we calculate the effective Yukawa couplings that are enhanced at large values of tan β for general soft supersymmetry-breaking mass parameters. We highlight the contributions due to non-universal terms in the flavour decompositions of the sfermion mass matrices. We present numerical examples illustrating how such terms are induced by renormalization-group evolution starting from universal input boundary conditions, and demonstrate their importance for the flavour-violating effective Yukawa couplings of quarks.
33971761
Lepton flavor violation as a probe of quark-lepton unification
The recent measurements of the solar neutrino mixing angle {theta}{sub sol} and the Cabibbo mixing angle {theta}{sub C} reveal a surprising relation, {theta}{sub sol}+{theta}{sub C}{approx_equal}({pi}/4), which has been interpreted as an evidence for quark-lepton unification. We show in realizations of quark-lepton unification that the PMNS mixing matrix can be decomposed into a CKM-like matrix and maximal mixing matrices. We explore a possibility to probe such implications by considering the relative sizes of branching ratios for the lepton flavor violating radiative decay processes, l{sub i}{yields}l{sub j}{gamma}, in the context of the supersymmetric standard model with heavy right-handed Majorana neutrinos.
118999114
CP violation in the semileptonic B(lepton 4) (B ---> D pi lepton neutrino) decays: multi - Higgs doublet model and scalar leptoquark models
$\mathrm{CP}$ violation from physics beyond the standard model is investigated in ${B}_{l4}$ decays: $\stackrel{\ensuremath{\rightarrow}}{B}D\ensuremath{\pi}l{\overline{\ensuremath{\nu}}}_{l}.$ In the decay process, we include various excited states as intermediate states decaying to the final hadrons, $D+\ensuremath{\pi}$. We consider the semileptonic decay to a tau lepton family as well. $\mathrm{CP}$ violation is implemented through complex scalar-fermion couplings in the multi-Higgs-doublet model and scalar-leptoquark models beyond the standard model. With these complex couplings, we calculate the $\mathrm{CP}$-odd rate asymmetry and the optimal asymmetry. We find that for ${B}_{\ensuremath{\tau}4}$ decays the optimal asymmetry is sizable and can be detected at $1\ensuremath{\sigma}$ level with about ${10}^{6}\char21{}{10}^{7}B$-meson pairs, for maximally allowed values of $\mathrm{CP}$-odd parameters in those extended models.
118840597
Longitudinal and transverse spin asymmetries for inclusive jet production at mid-rapidity in polarized p+p collisions at sqrt{s}=200 GeV
We report STAR measurements of the longitudinal double-spin asymmetry A_LL, the transverse single-spin asymmetry A_N, and the transverse double-spin asymmetries A_Sigma and A_TT for inclusive jet production at mid-rapidity in polarized p+p collisions at a center-of-mass energy of sqrt{s} = 200 GeV. The data represent integrated luminosities of 7.6 /pb with longitudinal polarization and 1.8 /pb with transverse polarization, with 50-55% beam polarization, and were recorded in 2005 and 2006. No evidence is found for the existence of statistically significant jet A_N, A_Sigma, or A_TT at mid-rapidity. Recent model calculations indicate the A_N results may provide new limits on the gluon Sivers distribution in the proton. The asymmetry A_LL significantly improves the knowledge of gluon polarization in the nucleon.
1430526
New measurements of the transverse beam asymmetry for elastic electron scattering from selected nuclei
Here we have measured the beam-normal single-spin asymmetry A{sub n} in the elastic scattering of 1-3 GeV transversely polarized electrons from 1H and for the first time from 4He, 12C, and 208Pb. For 1H, 4He and 12C, the measurements are in agreement with calculations that relate An to the imaginary part of the two-photon exchange amplitude including inelastic intermediate states. Surprisingly, the 208Pb result is significantly smaller than the corresponding prediction using the same formalism. Our results suggest that a systematic set of new An measurements might emerge as a new and sensitive probe of the structure of heavy nuclei.
5890165
Measurement of the W boson mass with the Collider Detector at Fermilab
We present a measurement of the W boson mass using data collected with the CDF detector during the 1994-1995 collider run at the Fermilab Tevatron. A fit to the transverse mass spectrum of a sample of 30115 W --> ev events recorded in an integrated luminosity of 84 pb(-1) gives a mass M-W=80.473 +/-0.065(stat) +/-0.092(syst) GeV/c(2). A fit to the transverse mass spectrum of a sample of 14740 W --> muv events from 80 pb(-1) gives a mass M-W=80,465 +/-0.100(stat)+/-0.103(syst) Ge V/c(2) The dominant contributions to the systematic uncertainties are the uncertainties in the electron energy scale and the muon momentum scale, 0.075 GeV/c(2) and 0.085 GeV/c(2), respectively. The combined value for the electron and muon channel is M-W=80.470 +/-0.089-GeV/c(2). When combined with previously published CDF measurements, we obtain M-W=80.433 +/-0.079 GeV/c(2).