119292340
Enhancement of dark matter relic density from late time dark matter conversions
We demonstrate that if the dark matter (DM) in the Universe contains multiple components, the possible interactions between the DM components may convert the heavier DM components into lighter ones. It is then possible that the lightest DM component with an annihilation cross section significantly larger than that of the typical weakly interacting massive particle (WIMP) may lead to a relic density in agreement with cosmological observations, due to an enhancement of number density from the DM conversion process at late time after the thermal decoupling. This may provide an alternative source of boost factor relevant to the positron and electron excesses reported by the recent DM indirect search experiments.
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.
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.
27463348
Implications of new data in charmless B decays
Based on the latest experimental data of B ->pi pi and pi K modes, a model-independent analytical analysis is presented. The CP-averaged branching ratio difference Delta R=R-c-R-n in B ->pi K decays with R-c=2Br(pi K-0(-))/Br(pi(-)(K) over bar (0)) and R-n=Br(pi K-+(-))/2Br(pi(0)(K) over bar (0)) is reduced though it remains larger than the prediction from the standard model (SM) as both measured R-n and R-c are enhanced, which indicates that a room for new physics becomes smaller. The present data of pi pi decay reduce the ratio vertical bar C/T vertical bar from the previous value of vertical bar C/T vertical bar similar or equal to 0.8 to vertical bar C/T vertical bar similar or equal to 0.65, which is still larger than the theoretical estimations based on QCD factorization and pQCD. Within SM and flavor SU(3) symmetry, the current pi K data also diminish the ratio vertical bar C/T-'vertical bar from the previous value vertical bar C'/T'vertical bar similar or equal to 2 to vertical bar C'/T'vertical bar similar or equal to 1.16 with a large strong phase delta(C)'similar or equal to-2.65, while its value remains much larger than the one extracted from the pi pi modes. The direct CP violation A(CP)(pi(0)(K) over bar (0)) is predicted to be A(CP)(pi(0)(K) over bar (0))=-0.15 +/- 0.03, which is consistent with the present data. Two kinds of new effects in both strong and weak phases of the electroweak penguin diagram are considered. It is found that both cases can reduce the ratio to vertical bar C'/T'vertical bar=0.40 similar to 0.80 and lead to roughly the same predictions for CP violation in pi K-0(0).
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.
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.
119257866
Higher moments of net baryon distribution as probes of the QCD critical point
It is crucially important to find an acceptance and late collision process independent observable in searching for the possible critical point predicted by QCD. By utilizing a multiphase transport (AMPT) model and ultrarelativistic quantum molecular dynamics (UrQMD) model, we study the centrality and evolution time dependence of higher moments of net baryon distribution in Au+Au collisions at sq root(s{sub NN})=17.3 GeV. The results suggest that kurtosis and skewness are less sensitive to the acceptance effect and late collision process. Thus, they should be good observables providing the information on the early stage of a heavy-ion collision. In addition, our study shows that the product of kurtosis times sigma{sup 2} of the net proton distribution is quite different from that of the net baryon distribution when the collision energy is lower than sq root(s{sub NN})=20 GeV, the Monte Carlo calculations on kurtosiscentre dotsigma{sup 2} have a deviation from the theoretical predictions.
119220905
From Liouville to Chern-Simons, Alternative Realization of Wilson Loop Operators in AGT Duality
We propose an SL(2,R) Chern-Simons description of Liouville field theory (LFT), whose correlation function duals to partition function of N=2 SU(2) gauge theories. We give the dual expressions for conformal blocks, fusion rules, and Wilson loop operators in Chern-Simons theory. By realizing Wilson loop operator in Liouville as a Hopf link in S^3 on which lives an SL(2,R) Chern-Simons theory, we obtain an alternative description of monodromy of this loop operator in Liouville field theory as the ratio of link invariants. We show how to calculate t'Hooft loops in the simplest example -- the N=4 super Yang-Mills theory. The results we obtained are consistant with those in 0909.0945 and 0909.1105.
13934764
A Holographic model for Non-Relativistic Superconductor
We build a holographic description of non-relativistic system for superconductivity in strongly interacting condensed matter via gauge/gravity duality. We focus on the phase transition and give an example to show that a simple gravitational theory can provide a non-relativistic holographical dual description of a superconductor. There is also a critical temperature like the relativistic case, below which a charged condensation field appears by a second order phase transition and the (DC) conductivity becomes infinite. We also calculated the frequency dependent conductivity.
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.
118585263
Azimuthal correlations in Pb--Pb and pp collisions measured with the ALICE detector
We present results from the measurements of azimuthal correlations of charged particles in $\sqrt{s_{_{NN}}}$ = 2.76 TeV Pb--Pb collisions and $\sqrt{s_{_{NN}}}$ = 7 TeV pp collisions. In addition, the comparison of the experimental measurements in pp collisions with those from Pythia and Phojet simulations are presented.