High Energy Gamma--Radiation from the Galactic Center due to Neutralino Annihilation

We study the NGS (Non--dissipative Gravitational Singularity) model, which successfully describes the non--linear stage of evolution of perturbations (see [1], [2] and references therein). This model predicts DM density distribution $\rho(r) \sim r^{-\alpha}$ with $\alpha \simeq 1.8$ which holds from very small distances $r_{\rm min} \simeq 0.01~{\rm pc}$ up to very large distances $r_{\rm max} \simeq 5~{\rm Mpc}$. Assuming the neutralino to be a CDM particle, we calculate the annihilation of neutralinos in the vicinity of the singularity (Galactic Center). If neutralinos are the dominant component of DM in our Galaxy, the produced energy is enough to provide the whole observed activity of the GC. Neutralinos of the most general composition and of mass in the range 20~{\rm GeV} \leq m_\c \leq 1~{\rm TeV} are considered. We find the neutralino compositions which give the relic density needed for the Mixed Dark Matter (MDM) model and we evaluate for these compositions the high--energy ($E_{\gamma} > 100 ~{\rm MeV}$) gamma--ray flux under the constraint that the radio flux is lower than the observational limit. The compositions with the detectable gamma--ray flux which we found are provided by a set of almost pure gaugino states with the neutralino mass between $100$ and $500$ GeV. We demonstrate that a detectable high--energy gamma--ray flux is produced by the neutralino annihilation also in the case when neutralinos provide a small fraction (down to $0.1 \%$) of the DM in our Galaxy. The predicted flux is $F_\gamma \sim 10^{-7}-10^{-8}~{\rm cm}^{-2}~{\rm s}^{-1}$ for E_\gamma \gsim 300~{\rm MeV}Comment: Plain TeX 11 pages 4 figures available on request. Preprint numbers LNGS 94/90 - DFTT 5/9

Heavy quark potential and quarkonia dissociation rates

Quenched lattice data for the quark-antiquark interaction (in terms of heavy quark free energies) in the color singlet channel at finite temperatures are fitted and used within the nonrelativistic Schroedinger equation formalism to obtain binding energies and scattering phase shifts for the lowest eigenstates in the charmonium and bottomonium systems in a hot gluon plasma. The partial dissociation rate due to the Bhanot-Peskin process is calculated using different assumptions for the gluon distribution function, including free massless gluons, massive gluons, and massive damped gluons. It is demonstrated that a temperature dependent gluon mass has an essential influence on the heavy quarkonia dissociation, but that this process alone is insufficient to describe the heavy quarkonia dissociation rates.Comment: 4 pages, 5 figures, contribution to the proceedings of the International Conference on Hard and Electromagnetic Probes of High Energy Nuclear Collisions, Ericeira, Portugal, Nov. 4-10, 200

Heavy-quark Langevin dynamics and single-electron spectra in nucleus-nucleus collision

The stochastic dynamics of heavy quarks in the fireball produced in heavy-ion collisions is followed through numerical simulations based on the Langevin equation. The modification of the final p_T spectra (R_AA) of c and b quarks, hadrons and single-electrons with respect to pp collisions is studied. The transport coefficients are evaluated treating separately the contribution of soft and hard collisions. The initial heavy-quark spectra are generated according to NLO-pQCD, accounting for nuclear effects through recent nPDFs. The evolution of the medium is obtained from the output of two hydro-codes (ideal and viscous). The heavy-quark fragmentation into hadrons and their final semileptonic decays are implemented according to up to date experimental data. A comparison with RHIC data for non-photonic electron spectra is given.Comment: 4 pages, 3 figures, Talk given at "Hot Quarks 2010", 21th-26th June 201

BK from the lattice with Wilson quarks

We report our results for the bag-parameter BK obtained from the quenched simulations on the lattice with Wilson fermions at three values of the lattice spacing. We implemented the method by which no subtraction of the mixing with other four-fermion dS=2 operators is needed. Our final result, in terms of the renormalisation group invariant bag-parameter, is BK = 0.96 +/- 0.10.Comment: 12 pages, 3 figures [version published in Eur.Phys.J.C

B and B_S decay constants from moments of Finite Energy Sum Rules in QCD

We use an appropriate combination of moments of finite energy sum rules in QCD in order to compute the B_q-meson decays constants f_B and f_{B_s}.We perform the calculation using a two-loop computation of the imaginary part of the pseudoscalar two point function in terms of the running bottom quark mass. The results are stable with the so called QCD duality threshold and they are in agreement with the estimates obtained from Borel transform QCD sum rules and lattice computations.Comment: 11 pages, 2 figure

Inclusive Decays of Bottom Hadrons in New Formulation of Heavy Quark Effective Field Theory

We apply the new formulation of heavy quark effective field theory (HQEFT) to the inclusive decays of bottom hadrons. The long-term ambiguity of using heavy quark mass or heavy hadron mass for inclusive decays is clarified within the framework of the new formulation of HQEFT. The $1/m_b$ order corrections are absent and contributions from $1/m_b^2$ terms are calculated in detail. This enables us to reliably extract the important CKM matrix element $|V_{cb}|$ from the inclusive semileptonic decay rates. The resulting lifetime ratios $\tau(B^0_s)/\tau(B^0)$ and $\tau(\Lambda_b)/\tau(B^0)$ are found to well agree with the experimental data. We also calculate in detail the inclusive semileptonic branching ratios and the ratios of the $\tau$ and $\beta$ decay rates as well as the charm countings in the $B^0$, $B^0_s$ and $\Lambda_b$ systems. For $B^0$ decays, all the observables are found to be consistent with the experimental data. More precise data for the $B^0$ decays and further experimental measurements for the $B^0_s$ and $\Lambda_b$ systems will be very useful for testing the framework of new formulation of HQEFT at the level of higher order corrections.Comment: 20 pages, RevTex, 8 figures, 3 tables, revised version with `dressed heavy quark' being addressed, to be published in Int. J. Mod. Phys.

e+e- --> e+e- pi0 pi0 at Daphne

The production of the sigma(500) meson in gamma gamma --> pi0 pi0 is studied. In particular, the KLOE data collected during the DAPHNE run at sqrt(s)= 1 GeV are appropriate to this purpose because of the strong reduction of Kaon backgrounds.Comment: 13 pages, 9 figures, few comments adde

Are the pentaquark sum rules reliable?

We rewiew and scrutinize the existing mass determinations of the pentaquarks from the exponential Laplace Sum Rules (LSR). We do not find any sum rule window for extracting optimal and reliable results from the LSR, due to the unusual slow convergence of the OPE and to the exceptional important role of the QCD continuum into the spectral function in this channel. Instead, we use in this channel,for the first time, Finite Energy Sum Rules (FESR), which exhibit a nice stability in the QCD continuum threshold t_c, at which one can extract, with a good accuracy, the mass of the lowest resonance. Including the D=7, 9 condensate contributions in the OPE, we obtain M_Theta=(1513+- 114) MeV, and the corresponding residue lambda_Theta^2= -(0.14-- 0.49)x 10^{-9} GeV^{12}, which favours the I=0, J=1/2, and negative parity S-wave interpretation of the Theta (1540). However, our analysis indicates a degeneracy between the unmixed I=0 and I=1 S-wave states. In the I=0, J=1/2, P-wave channel, we obtain, for the P-resonance, M_P = (1.99+- 0.19) GeV and lambda_P= -(0.7--7.1)x 10^{-9} GeV^{14}, which we expect to be discovered experimentally. Our results also suggest that some intuitive choices of the continuum threshold used in the LSR literature are inconsistent with the FESR results. Finally, a study of the Theta-K-N coupling using a vertex sum rule shows that, for the I=0, S-wave channel, the leading OPE contributions only start to order alpha_s^2 in the chiral limit m_s=0, indicating that the Theta is very narrow.Comment: Latex file 6 pages, 5 ps.figures. Contribution to the QCD 04 International Conference (Montpellier-5-9th July 2004) and to HEP-MAD 04 International Conference (Antananarivo 27th Sept-2nd Oct. 2004). To appear in Nucl. Phys. B (Proc. Suppl.) and in SLAC Econf. on-line Proceedings. Comments and References adde

Reconclining phi radiative decays with other data for a0(980), fo(980), pi-pi -> KK and pi-pi -> eta-eta

Data for phi -> gamma (eta-pizero) are analysed using the KK loop model and compared with parameters of a0(980) derived from Crystal Barrel data. The eta-pi mass spectrum agrees closely and the absolute normalisation lies just within errors. However, BES parameters for fo(980) predict a normalisation for phi -> gamma (pizero-pizero) at least a factor 2 lower than is observed. This discrepancy may be eliminated by including constructive interference between fo(980) and sigma. The magnitude required for sigma -> KK is consistent with data on pi-pi -> KK. A dispersion relation analysis by Buttiker, Descotes-Genon and Moussallam of pi-pi -> KK leads to a similar conclusion. Data on pi-pi -> eta-eta also require decays of sigma to eta-eta. Four sets of pi-pi -> KK data all require a small but definite fo(1370) signal.Comment: 21 pages, 11 figures, Small rearrangement of reference

QCD at high energy (experiments)

Recent measurements of QCD interactions involving large momentum transfers are reviewed. The status of measurements of the strong coupling constant is summarised. Recent developments in the measurement and interpretation of deep inelastic scattering, proton-anti-proton collisions and two-photon processes are discussed. While QCD at next-to-leading order gives a qualitative description of many processes, next-to-NLO calculations are now required to allow quantitative information to be extracted from hadron-initiated multijet data. This is illustrated by a discussion of recent data on the photoproduction of dijet events at HERA.Comment: Talk presented at the $31^{\rm st}$ International Conference on High Energy Physics, Amsterdam, 24-31 July 2002. 18 pages, 30 figure