51398146
Some properties of the newly observed X(1835) state at BES
Recently the BES collaboration has announced the observation of a resonant state in the π+π-η’ spectrum in J/ψ→γπ+π-η’ decay. Fitting the data with a 0-+ state, the mass is determined to be 1833.7 MeV with 7.7σ statistic significance. This state is consistent with the one extracted from previously reported pp̄ threshold enhancement data in J/ψ→γpp̄. We study the properties of this state using QCD anomaly and QCD sum rules, assuming X(1835) to be a pseudoscalar, and we show that it is consistent with the data. We find that this state has a sizeable matrix element $\langle0|G\widetilde{G}|G_{\text{p}}\rangle$, leading to branching ratios of (2.61–7.37)×10-3 and (2.21–10.61)×10-2 for J/ψ→γGp and for Gp→π+π-η′, respectively. Combining the calculated branching ratio of J/ψ→γGp and data on threshold enhancement in J/ψ→γpp̄, we determine the coupling for the Gp–p–p̄ interaction. We finally study the branching ratios of the other J/ψ→γ+three mesons decay modes. We find that J/ψ→γGp→γ(π+π-η,KKπ0) can provide useful tests for the mechanism proposed.
118468218
Interpretation of Zb(10610) and Zb(10650) in the ISPE mechanism and the Charmonium Counterpart
The initial single pion emission (ISPE) mechanism is applied to the processes Y(5S)→πB (∗) ¯ B (∗) ,w hose details have been recently reported at ICHEP2012, and we obtain reasonable agreement with Bell's measurements; that is, we succeed in reproducing the enhancement structures of Zb(10610) and Zb(10650). Inspired by this success, we also predict the corresponding enhancement structures in open charm one-pion decays of higher charmonia near the thresholds of D ∗ ¯ Da nd D ∗ ¯ D ∗ .
119249008
Does the enhancement observed in $\gamma\gamma\to D\bar{D}$ contain two P-wave higher charmonia?
We solve a new puzzle raised by the observation of an enhancement structure Z(3930) in $\gamma\gamma\to D\bar{D}$. If categorizing Z(3930) as χc2(2P), as suggested by Belle and BaBar, we must explain why χc0(2P) dominantly decaying into $D\bar{D}$ is missing in the $D\bar{D}$ invariant mass spectrum. In this work, we propose that the Z(3930) enhancement structure may contain two P-wave higher charmonia χc0(2P) and χc2(2P). We show that this assumption is supported by our analysis of the $D\bar{D}$ invariant mass spectrum and cosθ∗ distribution of $\gamma\gamma\to D\bar{D}$. This observation would not only provide valuable information of two P-wave higher charmonia χc0(2P) and χc2(2P), but also serve as the crucial test of our novel proposal to the observed enhancement structure Z(3930), especially at the forthcoming BelleII and the approved SuperB.
118170711
Towards two-body strong decay behavior of higher $\rho$ and $\rho_3$ mesons
In this work, we systematically study the two-body strong decay of the $\rho/\rho_3$ states, which are observed and grouped into the $\rho/\rho_3$ meson family. By performing the phenomenological analysis, the underlying properties of these states are obtained and tested. What is more important is that abundant information of their two-body strong decays is predicted, which will be helpful to further and experimentally study these states.
31555802
Mixing of Pentaquark and Molecular States
There are experimental evidences for the existence of narrow states Θ+ and Θc with the same quantum numbers of uudds̄ and uuddc̄ pentaquarks and also NK(∗) and ND(∗) molecular states. Their masses deviate from many theoretical estimates of the pure pentaquark and molecular states. In this work we study the possibility that the observed Θ+ and Θc are mixtures of pure pentaquark and molecular states. The mixing parameters are in general related to non-perturbative QCD which are not calculable at present. We determine them by fitting data from known states and then generalize the mechanism to Θb to predict its mass and width. The mixing mechanism can also naturally explain the narrow width for Θ+ and Θc through destructive interferences, even if the pure pentaquark and molecular states have much larger decay widths. We also briefly discuss the properties of the partner eigenstates of Θ+ and Θc and the possibility of experimentally observe them. Moreover, probable consequences of multi-state mixing are also addressed.
37345728
X(3915) and X(4350) as new members in the P-wave charmonium family.
The analysis of the mass spectrum and the calculation of the strong decay of P-wave charmonium states strongly purport to explain the newly observed X(3915) and X(4350) as new members in the P-wave charmonium family, i.e., chi{c0}{'} for X(3915) and chi{c2}{''} for X(4350). Under the P-wave charmonium assignment to X(3915) and X(4350), the J{PC} quantum numbers of X(3915) and X(4350) must be 0{++} and 2{++} respectively, which provide important criteria to test the P-wave charmonium explanation for X(3915) and X(4350) proposed by this Letter. The decay behavior of the remaining two P-wave charmonium states with the second radial excitation is predicted, and an experimental search for them is suggested.
119107906
Gauge-boson production with multiple jets near threshold
Signatures of new physics beyond the Standard Model are often characterized by large missing transverse energy ($\not E_T$) produced in association with multiple jets. The dominant Standard Model background to such processes comes from gauge-boson production in association with jets. A standard search strategy involves looking for an excess in the $m_{eff}$ distribution, where $m_{eff}= \not E_T +\sum_{J} p^T_J$ and $p^T_J$ denotes the transverse momentum of the $J$-th jet. The region of large $m_{eff}$ is dominated by jet production near threshold, giving rise to large Sudakov logarithms that can change the magnitude and shape of the $m_{eff}$ distribution. We present an effective theory framework for the resummation of such threshold logarithms. We perform an analysis for exclusive jet production using the N-jettiness global event shape, which allows theoretical control to also be maintained over large logarithms induced by vetoing additional jets. As a first step, we give explicit numerical results with next-to-leading-log (NLL) resummation for $pp \to \gamma + 2$ jets in the large $m_{eff}$ region.
7546995
Supersymmetry Changing Bubbles in String Theory
We give examples of string compactifications to 4d Minkowski space with different amounts of supersymmetry that can be connected by spherical domain walls. The tension of these domain walls is tunably lower than the 4d Planck scale. The ``stringy'' description of these walls is known in terms of certain configurations of wrapped Dirichlet and NS branes. This construction allows us to connect a variety of vacua with 4d = 4,3,2,1 supersymmetry.
118434102
Study of baryon octet electromagnetic form factors in perturbative chiral quark model
The electromagnetic properties of baryon octet are studied in the perturbative chiral quark model (PCQM). The relativistic quark wave function is extracted by fitting the theoretical results of the proton charge form factor to experimental data and the predetermined quark wave function is applied to study the electromagnetic form factors of other octet baryons as well as magnetic moments, charge and magnetic radii. The PCQM results are found, based on the predetermined quark wave function, in good agreement with experimental data.
118574295
Position Angle Changes of Inner-Jets in a Sample of Blazars
We have carried out the Gaussian model-fitting to 15 GHz VLBA cores for a sample of blazars from the MOJAVE database, analysed the correlations in the model-fitted parameters and studied the variability properties for different group of sources. We found that the Fermi LAT-detected blazars have on an average higher position angle changes of cores than the non-LAT detected blazars, and that the LAT-detected ones are associated with more variable cores in flux density.
118571453
Axial-vector f_1(1285)-f_1(1420) mixing and B_s \to J/\psi (f_1(1285), f_1(1420)) decays
Inspired by the very recent LHCb measurements of $B_s \to J/\psi f_1(1285)$ and the good agreement between the perturbative QCD predictions and the data for many $B \to J/\psi V$ decays, we here investigate the $B_s \to J/\psi f_1(1285)$ and $B_s \to J/\psi f_1(1420)$ decays for the first time by employing the perturbative QCD (pQCD) approach, in which the $1^3P_1$ states $f_1(1285)$ and $f_1(1420)$ are believed to be the mixture of flavor singlet $f_1$ and octet $f_8$ or of quark-flavor states $f_{1q}$ and $f_{1s}$. We show that the pQCD predictions for the branching ratio of $B_s \to J/\psi f_1(1285)$ agree well with the data within errors for the mixing angle $\theta_{^3P_1} \approx 20^\circ (\phi_{^3P_1} \approx 15^\circ)$ between $f_1 (f_{1q})$ and $f_8 (f_{1s})$ states. Furthermore, the branching ratio of $B_s \to J/\psi f_1(1420)$ and the large transverse polarization fractions in these two considered channels are also predicted and will be tested by the LHC and the forthcoming Super-B factory experiments. Based on the decay rates of $B_s \to J/\psi f_1(1285)$ and $B_s \to J/\psi f_1(1420)$ decay modes predicted in the pQCD approach, the extracted mixing angle between $f_1(1285)$ and $f_1(1420)$ is basically consistent with currently available experimental measurements and lattice QCD analysis within still large theoretical errors.