119278047
Charged charmoniumlike state $Z_c(3900)^±$ via meson photoproduction
In this work, we explore the production of the newly observed charged charmoniumlike state $Z_c(3900)^\pm$ by the photoproduction process $\gamma p\to Z_c(3900)^+n$. Our numerical result indicates that the maximum of the calculated total cross section of $\gamma p\to Z_c(3900)^+n$ can reach up to the order of $0.1 \mu b$. Furthermore, the Dalitz plot analysis is performed by considering the Pomeron exchange as the background contribution. This analysis shows that the $Z_c(3900)^+$ signal can be distinguished from the background easily and the best energy window of searching for $Z_c(3900)^+$ is $\sqrt{s}\simeq7$ GeV, which is important information for further experimental study of $Z_c(3900)^+$ by meson photoproduction.
28437592
A possible global group structure for exotic states
Based on the fact that the long expected pentaquark which possesses the exotic quantum numbers of $$B=1$$B=1 and $$S=1$$S=1 was not experimentally found, although exotic states of $$XYZ$$XYZ have been observed recently, we conjecture that the heavy flavors may play an important role in stabilizing the hadronic structures beyond the traditional $$q\bar{q}$$qq¯ and $$qqq$$qqq composites.
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.
119155043
Effects of hadronic loops on the direct CP violation of $B_c$
It is well-known that the final state interaction plays an important role in the decays of B meson. The contribution of the final state interaction, which is supposed to be long-distance effects, to the concerned processes can interfere with that of the short-distance effects produced via the tree and/or loop diagrams at quark-gluon level. The interference may provide a source for the direct CP violation A{sub CP} in the process B{sub c}{sup +}{yields}D{sup 0}{pi}{sup +}. We find that a typical value of A{sub CP} when the final state interaction effect is taken into account can be about -22% which is different from that without the final state interaction effect. Therefore, when we extract information on CP violation from the data which will be available at the Large Hadron Collider beauty experiment (LHCb) and the new experiments in B factories, the contribution from the final state interaction must be included. This study may be crucial for searching new physics in the future.
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 ∗ .
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.
119119786
Radio observations of the first three-months of Fermi AGN at 4.8 GHz
Using the Urumqi 25 m radio telescope, sources from the first t hree months of the Fermi-large area telescope detected active galactic nuclei (AGN) catalog with a declination of > 0 ◦ were observed in 2009 at 4.8 GHz. The radio flux density ap- peared to correlate with the -ray intensity. Intra-day variability (IDV) observations were performed in March, April and May 2009 for 42 selected -ray bright blazars, and ∼60% of them showed evidence of flux variability at 4.8 GHz duri ng the IDV observations. The IDV detection rate was higher than that in previous flat-spectrum AGN samples. IDV appeared more often in the very long baseline interferometry-core dominant blazars, and the non-IDV blazars showed relatively "steeper" spectral in- dices than the IDV blazars. Pronounced inter-month variability was also found in two BL Lac objects: J0112+2244 and J0238+1636.
102486763
High precision predictions for exclusive V H production at the LHC
A bstractWe present a resummation-improved prediction for pp → V H + 0 jets at the Large Hadron Collider. We focus on highly-boosted final states in the presence of jet veto to suppress the $ t\overline{t} $ background. In this case, conventional fixed-order calculations are plagued by the existence of large Sudakov logarithms $ \alpha_s^n{\log^m}\left( {{{{p_T^{\mathrm{veto}}}} \left/ {Q} \right.}} \right) $ for Q ~ mV + mH which lead to unreliable predictions as well as large theoretical uncertainties, and thus limit the accuracy when comparing experimental measurements to the Standard Model. In this work, we show that the resummation of Sudakov logarithms beyond the next-to-next-to-leading-log accuracy, combined with the next-to-next-to-leading order calculation, reduces the scale uncertainty and stabilizes the perturbative expansion in the region where the vector bosons carry large transverse momentum. Our result improves the precision with which Higgs properties can be determined from LHC measurements using boosted Higgs techniques.
119201963
SCET approach to top quark decay
Abstract In this work we study the QCD corrections to the top quark doubly decay rate with a detected B hadron containing a b quark. We focus on the regime among which the emitted W boson nearly carries its maximum energy. The tool that we use here is the soft-collinear effective theory (SCET). The factorization theorem based on SCET indicates a novel fragmenting jet function. We calculate this function to next-to-leading order in α s . Large logarithms due to several well separated scales are summed up using the renormalization group equation (RGE). Finally we reach an analytic formula for the distribution which could easily be generalized to other heavy hadron decays.
14339384
Heterotic moduli stabilization with fractional Chern-Simons invariants
We show that fractional flux from Wilson lines can stabilize the moduli of heterotic string compactifications on Calabi-Yau threefolds. We observe that the Wilson lines used in GUT symmetry breaking naturally induce a fractional flux. When combined with a hidden-sector gaugino condensate, this generates a potential for the complex structure moduli, Kahler moduli, and dilaton. This potential has a supersymmetric AdS minimum at moderately weak coupling and large volume. Notably, the necessary ingredients for this construction are often present in realistic models. We explore the type IIA dual phenomenon, which involves Wilson lines in D6-branes wrapping a three-cycle in a Calabi-Yau threefold, and comment on the nature of the fractional instantons that change the Chern-Simons invariant.
119302053
Empirical extinction coefficients for the GALEX, SDSS, 2MASS and WISE passbands
Using the "standard pair" technique of paring stars of almost nil and high extinction but otherwise of almost identical stellar parameters from the SDSS, and combing the SDSS, GALEX, 2MASS and WISE photometry ranging from the far UV to the mid-IR, we have measured dust reddening in the FUV-NUV, NUV-u, u-g, g-r, r-i, i-z, z-J, J-H, H-Ks, Ks-W1 and W1-W2 colors for thousands of Galactic stars. The measurements, together with the E(B-V) values given by Schlegel et al. (1998), allow us to derive the observed, model-free reddening coefficients for those colors. The results are compared with previous measurements and the predictions of a variety of Galactic reddening laws. We find that 1) The dust reddening map of Schlegel et al. (1998) over-estimates E(B-V) by about 14 per cent, consistent with the recent work of Schlafly et al. (2010) and Schlafly & Finkbeiner (2011); 2) All the new reddening coefficients, except those for NUV-u and u-g, prefer the R(V) = 3.1 Fitzpatrick reddening law rather than the R(V) = 3.1 CCM and O'Donnell (O'Donnell 1994) reddening laws. Using the Ks-band extinction coefficient predicted by the R(V) = 3.1 Fitzpatrick law and the observed reddening coefficients, we have deduced new extinction coefficients for the FUV, NUV, u, g, r, i, z, J, H, W1 and W2 passbands. We recommend that the new reddening and extinction coefficients should be used in the future and an update of the Fitzpatrick reddening law in the UV is probably necessary. We stress however that the FUV- and NUV-band coefficients should be used with caution given their relatively large measurement uncertainties. Finally, potential applications of the "standard pair" technique with the LAMOST Galactic surveys are discussed.