118397979
Signal of New Physics and Test of Isospin-SU(3) Relations and CP Violation in Charmless B Decays
A model-independent analytical analysis for charmless B decays is presented. It is demonstrated that the CP-averaging branching ratio difference $\Delta R = R_c - R_n$ in $B\to \pi K$ decays with $R_c = 2Br(\pi^0K^-)/Br(\pi^-\bar{K}^0)$ and $R_n =Br(\pi^+K^-)/2Br(\pi^0\bar{K}^0)$ defines a sensitive quantity for probing new physics as $\Delta R$ is dominated by the second order of electroweak penguin contributions. A large discrepancy between experimental data and standard model (SM) prediction $\Delta R^{exp}/\Delta R^{SM} > 9.0\pm 5.0$ strongly indicates a signal of new physics in the electroweak penguin sector. Within the SM, the current $\pi K$ data favor a very large color-suppressed tree amplitude $|C'/T'|\sim 2$, large CP violations ($A_{CP}(\pi^0\bar{K}^0)\sim 0.69$ and $A_{CP}(\pi^0\bar{K}^-)\sim 0.56$), which is connected to $\Delta R$ and be solved simultaneously with extra electroweak penguin contributions. More accurate measurements on the ratio difference $\Delta R$ and CP violation in $B\to \pi \pi, \pi K$ decays may provide a window for probing new physics and testing the isospin and SU(3) symmetries.
118710048
Probing the fourth generation Majorana neutrino dark matter
The heavy fourth-generation Majorana neutrino can be stable and contribute to a small fraction of the relic density of dark matter (DM) in the Universe. Because of its strong coupling to the standard model particles, it can be probed by the current direct and indirect DM detection experiments even it is a subdominant component of the whole halo DM. Assuming that it contributes to the same fraction of the local halo DM density as that of the DM relic density in the Universe, we show that the current Xenon100 data constrain the mass of the stable Majorana neutrino to be greater than the mass of the top quark. In the mass range from 200 GeV to a few hundred GeV, the effective spin-independent cross section for the neutrino elastic-scattering off nucleon is insensitive to the neutrino mass and mixing, and is predicted to be similar to 1.5 X 10(-44) cm(2), which can be reached by the direct DM detection experiments soon. In the same mass region the predicted effective spin-dependent cross section for the heavy neutrino scattering off proton is in the range of 2 X 10(-40) cm(2) similar to 2 X 10(-39) cm(2), which is within the reach of the ongoing DM indirect search experiments such as IceCube. We demonstrate such properties of the heavy neutrino DM in a fourth-generation model with the stability of the fourth Majorana neutrino protected by an additional generation-dependent U(1) gauge symmetry.
123787607
The Contribution of Reggeon in charge exchange processes
We discuss in this paper The experimental results on maximum psedo-rapidity $\eta_{max}$ distribution in the charge exchange process $e+p\to e+n+X$ in ZEUS Collaboration at HERA. We calculate the contributions of \regg ($\rho$-Reggeon associated with $\rho$ meson) from regge phenomenology and $\pi^{+}$-exchange from pion cloud model. The results show that neither the \regg-exchange nor the pion cloud model alone can explain the experimental data well, but after considering both these two processes together, by using Monte Carlo simulation, a good agreement between theoretical results and experimental data is found. This means that in discussing the large rapidity gap phenomena in deep inelastic scattering, both of the two processes play substantial role.
119061151
Weak phase gamma and strong phase delta from CP averaged B ->pi pi and pi K decays
Assuming SU(3) symmetry for the strong phases in the four decay modes B-->pi(-)pi(+), pi(0)pi(+), pi(-)K(+), pi(-)(K) over bar(0) and ignoring the relative small electroweak penguin effects in those decays, the weak phase gamma and the strong phase delta can be determined in a model independent way by the CP averaged branching ratios of the four decay modes. It appears that the current experimental data for B-->pi pi and pi K decays prefer a negative value of cos gamma cos delta. By combining with the other constraints from V-ub B-d,s(0)-(B) over bar(d,s)(0) mixing, and the indirect CP-violating parameter epsilon(K) within the standard model, two favorable solutions for the phases gamma and delta are found to lie in the region 35 degrees less than or similar to gamma less than or similar to 62 degrees and 106 degrees less than or similar to delta less than or similar to 180 degrees or 86 degrees less than or similar to gamma less than or similar to 151 degrees and 0 degrees less than or similar to delta less than or similar to 75 degrees within 1 sigma standard deviation. It is noted that if allowing the standard deviation of the data to be more than 1 sigma, the two solutions could approach one solution with a much larger region for the phases gamma and delta. Direct CP asymmetry a(epsilon")((pi-K+)) in B -->pi(-)K(+) decay can be as large as the present experimental upper bound. Direct CP asymmetry a(epsilon")((pi+)pi-) in B-->pi(-)pi(+) decay can reach up to about 40% at the 1 sigma level.
119263633
Two Higgs bi-doublet left-right model with spontaneous P and CP violation
A left-right symmetric model with two Higgs bi-doublet is shown to be a consistent model for both spontaneous P and CP violation. The flavor changing neutral currents can be suppressed by the mechanism of approximate global U(1) family symmetry. The constraints from neural K meson mass difference ΔmK are calculated and it is demonstrated that a right-handed gauge boson W2 contribution in box-diagrams with mass well below 1 TeV is allowed due to a cancelation caused by a light-charged Higgs boson with a mass range of 150–300 GeV. The W2 contribution to εK can be suppressed from an appropriate choice of additional CP phases appearing in the right-handed Cabbibo-Kobayashi-Maskawa matrix. The model is also found to be fully consistent with B0 mass difference ΔmB and the mixing induced CP violation sin2βJ/ Ψ, which is usually difficult for the model with only one Higgs bi-doublet. The new physics beyond the standard model can be directly searched at the colliders LHC and ILC.
115775190
More precise determination of V-cb & V-ub and direct CP violation in charmless B decays
More precise extractions on the two important CKM matrix elements \V-cb\ and \V-ub\ are presented up to 1/m(Q)(2) corrections, based on the complete heavy-quark effective field theory (HQEFT) of QCD. The HQEFT as a large component QCD provides us with a complete theoretical framework for correctly and systematically evaluating the subleading and higher-order contributions in 1/m(Q) expansion of heavy quarks. A global analysis on charmless B decays is made, based on the isospin and SU(3) flavor symmetry. An isospin relation is found to be very useful for studying SU(3) symmetry-breaking effects of strong phases and exploring new types of electroweak penguin effects. The direct CP violation in charmless B decays is predicted, and its precise measurement is helpful either for testing SU(3) symmetry breaking effects of strong phases or for probing news physics beyond standard model.
119286757
Dirac neutrinos with S"4 flavor symmetry in warped extra dimensions
We present a warped extra dimension model with the custodial symmetry SU(2)(L) x SU(2)(R) x U(1)(X) x P-LR based on the flavor symmetry S-4 X Z(2) x Z(2)', and the neutrinos are taken to be Dirac particles. At leading order, the democratic lepton mixing is derived exactly, and the high-dimensional operators introduce corrections of order lambda(c) to all the three lepton mixing angles such that agreement with the experimental data can be achieved. The neutrino mass spectrum is predicted to be of the inverted hierarchy and the second octant of theta(23) is preferred. We suggest the modified democratic mixing, which is obtained by permuting the second and the third rows of the democratic mixing matrix, should be a good first order approximation to understanding sizable theta(13) and the first octant of theta(23). The constraints on the model from the electroweak precision measurements are discussed. Furthermore, we investigate the lepton mixing patterns for all the possible residual symmetries G(nu) and G(l) in the neutrino and charged lepton sectors, respectively. (C) 2013 Elsevier B.V. All rights reserved.
118334948
Non-Hermitian perturbations to the Fritzsch textures of lepton and quark mass matrices
Abstract We show that non-Hermitian and nearest-neighbor-interacting perturbations to the Fritzsch textures of lepton and quark mass matrices can make both of them fit current experimental data very well. In particular, we obtain θ 23 ≃ 45 ° for the atmospheric neutrino mixing angle and predict θ 13 ≃ 3 ° to 6° for the smallest neutrino mixing angle when the perturbations in the lepton sector are at the 20% level. The same level of perturbations is required in the quark sector, where the Jarlskog invariant of CP violation is about 3.7 × 10 − 5 . In comparison, the strength of leptonic CP violation is possible to reach about 1.5 × 10 − 2 in neutrino oscillations.
119117650
Anisotropic flow of identified particles in Pb--Pb collisions at $\sqrt{s_{_{\rm NN}}} =$ 2.76 TeV with the ALICE detector
The measurement of anisotropic flow of identified particles, including charged pion, kaon, (anti-)proton as well as strange and multi-strange particles (${\rm K_{S}^{0}}$, ${\rm \Lambda}$, ${\rm \Xi}$ and ${\rm \Omega}$) are measured in Pb--Pb collisions at $\sqrt{s_{_{{\rm NN}}}}$ = 2.76 TeV with the ALICE detector. The results are compared to measurements at RHIC and hydrodynamic model calculations. The mass splitting and the scaling with the number of constituent quarks of the anisotropic flow are also discussed.
14612850
Holographic melting of heavy baryons in plasma with gluon condensation
We propose a Dirac-Born-Infeld (DBI) D5 vertex brane plus N(c) fundamental strings configuration to describe a baryon probe in strongly coupled gauge theory with gluon condensation at finite temperature via AdS/CFT correspondence. We investigate properties of this configuration in a dilaton deformed AdS(5) x S(5) background, in which IIB string theory is dual to super Yang-Mills theory in a state with a constant self-dual gauge field (F(mn) = F(mn)*) background. We find that for most values of temperature T and gluon condensation parameter q (q = pi(2) ), there always exists a screening length L(s). The relation L(s) similar to 1/T has been checked. We give the q dependence of L(s). We calculate the boost velocity nu(nu = - tanh eta) and angular velocity omega dependence of L(s) for a baryon probe, and obtain L(s) = L(0)* (1-nu(2))(1/4) for large nu and L(s) similar to omega(-1), which are consistent with those dependence relations in the point brane plus strings case, and find that the usual relations have been modified by q. We also calculate the mass of baryon and find T dependence of baryon mass.
123402029
Interpreting N M2 branes