In this work, we present the mass spectrum of higher charomona around and above 4.6 GeV by adopting the unquenched potential model. We perform a combined fit to the updated experimental data of $e^+e^- \to ψ(2S)π^+π^-$ and $e^+e^-\to Λ_c\barΛ_c$. To understand the "platform" structure observed in the range of $4.57 \sim 4.60$ GeV existing in the $Λ_c\barΛ_c$ invariant mass spectrum of $e^+e^-\to Λ_c\barΛ_c$ of BESIII, we introduce two resonances in this combined fit to the $e^+e^- \to ψ(2S)π^+π^-$ and $e^+e^-\to Λ_c\barΛ_c$, which have resonance parameters, $m_{Y_1}=4585\pm2$ MeV, $Γ_{Y_1}=29.8\pm8.0$ MeV, $m_{Y_2}=4676\pm7$ MeV, and $Γ_{Y_2}=85.7\pm15.0$ MeV. Furthermore, combining with our theoretical results, we indicate that the two charmonium-like $Y$ states can be due to two higher charmonia, which are mixtures of $6S$ and $5D$ $c\bar{c}$ states. Their two-body open-charm decay behaviors are given. Under the same framework, our analysis of the data of $e^+e^-\to D_{s}^+D_{s1}(2536)^-$ recently released by Belle supports to introduce these two higher charmonia around 4.6 GeV. Additionally, we predict the masses and two-body open-charm decays of six higher charmonia $ψ(nS)$ and $ψ(mD)$ with $n=7,8,9$ and $m=6,7,8$ above 4.6 GeV. Search for these higher charmonia will be an interesting issue for the running BESIII and BelleII, and even the possible Super Tau-Charm Factory discussed in China.
In the framework of quark-hadron duality, the cross section values of charmonium and doubly charmed baryon production in $e^+e^-$-annihilations have been estimated at interaction energy $\sqrt{s}=10.6$ GeV. It has been shown that the approach under discussion allows to resolve some contradictions between the experimental data and pQCD predictions.
Recent measurements of the Belle Collaboration of the exclusive production of two charmonia in the $e^+e^-$ annihilation differ substantially from theoretical predictions. Recently it was suggested that a significant part of this discrepancy can be explained by the process $e^2e^- --> 2J/psi$ and value for its cross-section was published. In this paper it is shown, that these results are incorrect and the values for the cross-sections of the production of different vector charmonia are presented.
We discuss the possibilities of producing the X(3872), which is assumed to be a D \bar D^* bound state, in radiative decays of charmonia. We argue that the ideal energy regions to observe the X(3872) associated with a photon in e^+e^- annihilations are around the Y(4260) mass and around 4.45 GeV, due to the presence of the S-wave D \bar D_1(2420) and D^* \bar D_1(2420) threshold, respectively. Especially, if the Y(4260) is dominantly a D \bar D_1 molecule and the X(3872) a D \bar D^* molecule, the radiative transition strength will be quite large.
The $1^1D_2 (c\bar c)$ state is the ground state of spin-singlet D-wave charmonia. Although it has not been found yet, the experimental data accumulate rapidly. This charmonium attracts more and more attention, especially when the BaBar Collaboration finds that the X(3872) particle has negative parity. In this paper we calculate the double-gamma and double-gluon annihilation processes of $^1D_2$ charmonia and bottomonia by using the instantaneous Bethe-Salpeter method. We find the relativistic corrections make the decay widths of $1^1D_2 (c\bar c)$ 2$\sim$5 times smaller than the non-relativis…
As a test of the color-singlet mechanism of the nonrelativistic QCD (NRQCD) factorization approach, we consider the exclusive two-quarkonium productions in electron-positron annihilation e+ e- -> eta_c + gamma and e+ e- -> J/psi + J/psi at B factories. The cross sections are computed to the next-to-leading order in alpha_s and are resummed to all orders in half the relative velocity v of the charm quark in each meson rest frame. The available theoretical prediction of the cross section for e+ e- -> J/psi + eta_c at the same level of theoretical accuracies is consistent with the available exper…
Exotic charmonium-like states have been targeted by various experiments in the last 15 years, but their nature still is unknown. Photo-(muo)production is a new promising instrument to study them. COMPASS, a fixed target experiment at CERN, analyzed the full set of the data collected with a muon beam between 2002 and 2011, covering the range from 7 GeV to 19 GeV in the centre-of-mass energy of the (virtual)photon-nucleon system. Production of the X(3872) state in the reaction $μ^+~N \rightarrow μ^+(J/ψπ^+π^- )π^{\pm} N'$ has been observed with a statistical significance of around 5 $σ$. The sha…
We study strong decays of the possible fully-charm tetraquarks recently observed by LHCb, and calculate their relative branching ratios through the Fierz rearrangement. Together with our previous QCD sum rule study [Phys. Lett. B 773, 247 (2017)], our results suggest that the broad structure around $6.2$-$6.8$ GeV can be interpreted as an $S$-wave $cc\bar c \bar c$ tetraquark state with $J^{PC} = 0^{++}$ or $2^{++}$, and the narrow structure around 6.9 GeV can be interpreted as a $P$-wave one with $J^{PC} = 0^{-+}$ or $1^{-+}$. These structures were observed in the di-$J/ψ$ invariant mass spec…
We calculate the contributions from QED processes involving two virtual photons to the cross sections for e^+ e^- annihilation into two charmonium states with the same C-parity. Generically, the cross sections are three orders of magnitude smaller than those for charmonia with opposite C-parity because they are suppressed by a factor of alpha^2/alpha_s^2. However, if both charmonia have quantum numbers J^{PC} = 1^{--}, then there is a contribution to the cross section that involves the fragmentation of each photon into a charmonium. The fragmentation contribution is enhanced by powers of E_{be…
We calculate the annihilation decay rates of the $^3D_2(2^{--})$ and $^3D_3(3^{--})$ charmonia and bottomonia by using the instantaneous Bethe-Salpeter method. The wave functions of states with quantum numbers $J^{PC}=2^{--}$ and $3^{--}$ are constructed. By solving the corresponding instantaneous Bethe-Salpeter equations, we obtain the mass spectra and wave functions of the quarkonia. The annihilation amplitude is written within Mandelstam formalism and the relativistic corrections are taken into account properly. This is important, especially for high excited states, since their relativistic…
We incorporate the color-screening effect due to light quark pair creation into the heavy quark-antiquark potential, and investigate the effects of screened potential on the spectrum of higher charmonium. We calculate the masses, electromagnetic decays, and E1 transitions of charmonium states in the screened potential model, and propose possible assignments for the newly discovered charmonium or charmonium-like $"X,Y,Z"$ states. We find the masses of higher charmonia with screened potential are considerably lower than those with unscreened potential. The $χ_{c2}(2P)$ mass agrees well with that…
We examine the status of charmonia like states by looking into the behaviour of the energy level differences and regularity in the behaviour of the leptonic decay widths of the excited charmonia states. The spectroscopic states are studied using a phenomenological Martin-like confinement potential and their radial wave functions are employed to compute the di-leptonic decay widths. Their deviations from the expected behaviour provide a clue to consider them as admixtures of the nearby S and D states. The present analysis strongly favour \$$\backslash$psi \$ (3686) as admixture of $c \bar{c}$ (…
Recently, ATLAS and CMS collaboration reported an excess in the diphoton events, which can be explained by a new resonance with mass around 750 GeV. In this work, we explored the possibility of identifying if the hypothetical new resonance is produced through gluon-gluon fusion or quark-antiquark annihilation, or tagging the beam. Three different observables for beam tagging, namely the rapidity and transverse momentum distribution of the diphoton, and one tagged bottom-jet cross section, are proposed. Combining the information gained from these observables, a clear distinction of the producti…
The diffractive t-slope, B_V, of elastic charmonia (V=J/psi, psi') photo- and leptoproductions off a nucleon is studied at low |t| (< 1 GeV^2) in the leading logarithmic approximation of perturbative QCD, with a special emphasis on the space-time evolution of the c\bar{c}-dipole. We obey a framework based on QCD factorization, which describes a certain Fermi motion effect due to the $c(\bar{c})$-quarks in the proper manner and includes appropriately kinematical corrections of the momentum transfer Delta_perp in the t-channel. Assuming the universal two-gluon form factor of the nucleon, we show…
We present a detailed analysis on the $B_c$ meson semi-leptonic decays, $B_c \to η_c (J/ψ) \ell ν$, up to next-to-leading order (NLO) QCD correction. We adopt the principle of maximum conformality (PMC) to set the renormalization scales for those decays. After applying the PMC scale setting, we determine the optimal renormalization scale for the $B_c\toη_c(J/ψ)$ transition form factors (TFFs). Because of the same $\{β_0\}$-terms, the optimal PMC scales at the NLO level are the same for all those TFFs, i.e. $μ_r^{\rm PMC} \approx 0.8{\rm GeV}$. We adopt a strong coupling model from the massive …
How to hunt for higher $P$-wave states of charmonium is still an open topic when $2P$ charmonia were identified. {In this work, we present an unquenched quark model calculation to illustrate the spectroscopy behavior of these $3P$, $4P$ and $5P$ states in charmonium family.} For the $3P$ charmonia, the predicted masses are around 4.2 GeV and their two-body open-charm decay behaviors were given, by which we propose that searching for these $3P$ states via their open-charm decay channels from $γγ$ fusion and $B$ decay can be accessible at future experiment like LHCb and Belle II. We continue to …
We show that the behavior of the excitation curves of some $e^+e^-$ annihilation processes close to the nucleon-antinucleon threshold can be explained either by the $ρ(1900)$ resonance itself or by its interference with other resonances. Besides the six-pion annihilation and the $e^+e^- \to K^+K^-π^+π^-$ and $e^+e^- \to Φπ^0$ processes, we also analyze the final states $ηπ^+ π^-$, $K^+ K^- π^+ π^- π^0$, and $K^+ K^-π^0 π^0$, the behavior of which around 1.6 GeV has not yet attracted attention. Analysis of the data on the $e^+e^- \to p \bar p$ and $e^+e^- \to n \bar n$ reactions clearly shows t…
The measurements of the total cross section of the $ e^+e^-\toγγ$ reaction from the VENUS, TOPAS, OPAL, DELPHI, ALEPH and L3 collaborations, collected between 1989 to 2003, are used to perform a $ χ^{2} $ test to search for a finite interaction length in direct contact term. The experimental data of the total cross section compared to the QED cross section of a $ χ^{2} $ test allows, to set limit on a finite interaction length $ r_{e}=(1.25\pm 0.16) \times 10 ^{-17} [cm] $. In the direct contact term annihilation is this interaction lengths a measure for the size of the electron.
Recent measurements by the Belle Collaboration of the exclusive production of two charmonia in e^+ e^- annihilation differ substantially from theoretical predictions. We suggest that a significant part of the discrepancy can be explained by the process e^+ e^- -> J/psi + J/psi. Because the J/psi + J/psi production process can proceed through fragmentation of two virtual photons into two cc-bar pairs, its cross section may be larger than that for J/psi +eta_c by about a factor 1.8, in spite of a suppression factor alpha^2/alpha_s^2 that is associated with the QED and QCD coupling constants.
We study charmoinum correlators and spectral functions at finite temperature within the quenched approximation using isotropic lattices with lattice spacing a^-1=4.86 GeV and 9.72 GeV. Although we observe some medium modifications of the ground state charmonium spectral function above deconfinement, we find that ground state charmonia (J/psi and eta_c) exist in the deconfined phase at least up to temperatures as high as 1.5Tc. P-wave charmonia (chi_c) on the other hand are dissociated already at 1.12Tc.
Using the CLEO III detector, we measure absolute cross sections for e+e- -> hadrons at seven center-of-mass energies between 6.964 and 10.538 GeV. R, the ratio of hadronic and muon pair production cross sections, is measured at these energies with a r.m.s. error <2% allowing determinations of the strong coupling alpha_s. Using the expected evolution of alpha_s with energy we find alpha_s(M_Z^2)=0.126 +/- 0.005 ^{+0.015}_{-0.011}, and Lambda=0.31^{+0.09+0.29}_{-0.08-0.21}.
This paper gives results for the spectrum, all allowed E1 radiative partial widths (and some important M1 widths) and all open-charm strong decay amplitudes of all 40 c-cbar states expected up to the mass of the 4S multiplet, just above 4.4 GeV. The spectrum and radiative widths are evaluated using two models, the relativized Godfrey-Isgur model and a nonrelativistic potential model. The electromagnetic transitions are evaluated using Coulomb plus linear plus smeared hyperfine wavefunctions, both in a nonrelativistic potential model and in the Godfrey-Isgur model. The open-flavor strong decay …
Charmonium states can decay into pairs of $D$ and $\overline{D}$ mesons if their masses are above the allowed decay thresholds. In general $c\bar{c}$ states near threshold will also undergo mixing with $D\overline{D}$ molecular (or tetraquark) states, by creation and annihilation of light quark-antiquark pairs. The investigation of such effects sheds light on the higher Fock state contributions to charmonium wavefunctions and on mass shifts, relative to a scenario where such mixing effects are neglected. A variational approach is applied to a mixing matrix between operators of both sectors, of…
Recently a novel hadronic state of mass 6.9 GeV, that decays mainly to a pair of charmonia, was observed in LHCb. The data also reveals a broader structure centered around 6490 MeV and suggests another unconfirmed resonance centered at around 7240 MeV, very near to the threshold of two doubly charmed $Ξ_{cc}$ baryons. We argue in this note that these exotic hadrons are genuine tetraquarks and not molecules of charmonia. It is conjectured that they are V-baryonium tetraquarks, namely, have an inner structure of a baryonic vertex with a $cc$ diquark attached to it, which is connected by a string…
The multiplicity distributions at high energy $e^+e^-$ annihilation are described well within the Two Stage Model in the region from 14 to 189 GeV. Energy dependence of parameters of this model gives the dynamic picture of the parton stage and the stage of hadronization. It is shown that oscillations in sign of the ratio of factorial cumulant moments over factorial moments of increasing order can be confirmed by this model.
Very recently, the {\it BABAR} Collaboration indicated that there exist an explicit enhancement structure near 2.2 GeV when focusing on the $e^+e^-\toπ^+π^-$ process again, which inspires our interest in studying the production of higher $ρ$ mesonic states. Since the branching ratio of $π^+π^-$ channel of $D-$wave $ρ$ states are much smaller than $S-$wave states, we choose $ρ(1900)$ and $ρ(2150)$ as the intermediate states in $e^+e^-\toπ^+π^-$, where $ρ(1900)$ and $ρ(2150)$ are treated as $ρ(3S)$ and $ρ(4S)$ states, respectively. Our result indicates that the $BABAR$'s data of $e^+e^-\toπ^+π^-…
Data recorded by the JADE experiment at the PETRA e^+e^- collider were used to measure the event shape observables thrust, heavy jet mass, wide and total jet broadening and the differential 2-jet rate in the Durham scheme. For the latter three observables, no experimental results have previously been presented at these energies. The distributions were compared with resummed QCD calulations (O(alpha_s^2)+NLLA), and the strong coupling constant alpha_s(Q) was determined at different energy scales Q=sqrt{s}. The results, α_s(22 GeV) = 0.161 ^{+0.016}_{-0.011}, α_s(35 GeV) = 0.143 ^{+0.011}_{-0.00…
In this paper we study inclusive production of vector charmonium states $J/ψ$ or $ψ(2S)$ in two-photon $\epem$-annihilation at $\sqrt s=10.6 \rm GeV$ using color-singlet model. Analytic expressions for differential cross sections, numerical values of total cross sections and plots of different distributions are presented. These distributions differ significantly from the one-photon case so these modes can be easily separated.
The calculational precision of $\ee\to\tautau$ and $\ee\to\mumu$ production cross-sections in electron-positron annihilations at \roots = 10.58 \gev are studied for the \kk Monte Carlo simulation program. We determine $σ(\ee\to\tautau) = (0.919 \pm 0.003) \nb$ and $σ(\ee\to\mumu) = (1.147 \pm 0.005) \nb$, where the error represents the precision of the calculation.
This work presents indirect searches for dark matter (DM) as WIMPs (Weakly Interacting Massive Particles) using neutrino data recorded by the Super-Kamiokande detector from 1996 to 2014. The results of the search for WIMP-induced neutrinos from the Sun and the Milky Way are discussed. We looked for an excess of neutrinos from the Sun/Milky Way direction compared to the expected atmospheric neutrino background. Event samples including both electron and muon neutrinos covering a wide range of neutrino energies (GeV to TeV) were used, with sensitivity to WIMP masses down to tens of GeV. Various W…
In this paper the production of excited vector and pseudoscalar charmonium mesons in $\epem$ annihilation is analyzed in the framework of light cone. In particular the cross sections $\epem \to ψ(2S)η_c(1S), ψ(1S)η_c(2S),ψ(2S)η_c(2S)$ have been calculated. It is shown, that contrary to NRQCD the cross sections calculated in the framework of light cone agree with experimental data.
In the precedent paper of the authors (hep-ph/0510410), the $b\bar b$ states were treated in the framework of the spectral integral equation, together with simultaneous calculations of radiative decays of the considered bottomonia. In the present paper, such a study is carried out for the charmonium $(c\bar c)$ states. We reconstruct the interaction in the $c\bar c$-sector on the basis of data for the charmonium levels with $J^{PC}=0^{-+}$, $1^{--}$, $0^{++}$, $1^{++}$, $2^{++}$, $1^{+-}$ and radiative transitions $ψ(2S)\toγχ_{c0}(1P)$, $γχ_{c1}(1P)$, $γχ_{c2}(1P)$, $γη_{c}(1S)$ and $χ_{c0}(1P…
In this work we study the process $e^{+}+e^{-}\longrightarrow J/Ψ+η_{c} $ at energy $\sqrt{s}= 10.6 GeV$ observed recently at B-factories whose measurements were made by Babar and Belle groups. We calculate the cross section for this process in the Bethe-salpeter formalism under Covariant Instantaneous Anstaz (CIA). To simplify our calculation, the heavy quark approximation $(q<<M, P M)$ is employed in the quark and gluon propagators. In the exclusive process of $e^{+}e^{-}$ annihilation into two heavy quarkonia, the cross section calculated in this scenario is compatible with the experimental…
We consider the use of directionality in the search for monoenergetic sub-GeV neutrinos arising from the decay of stopped kaons, which can be produced by dark matter annihilation in the core of the Sun. When these neutrinos undergo charged-current interactions with a nucleus at a neutrino detector, they often eject a proton which is highly peaked in the forward direction. The direction of this track can be measured at DUNE, allowing one to distinguish signal from background by comparing on-source and off-source event rates. We find that directional information can enhance the signal to backgro…
Measurements by the Belle Collaboration of the exclusive production of two charmonia in e^+ e^- annihilation differ substantially from theoretical predictions. Till now, no conclusive explanation for this remarkable discrepancy has been provided. Even the origin of the discrepancy is not identified, yet. We suggest that the measurement of four-charm events in Belle data must provide a strong constraint in identifying the origin of this large discrepancy. Our prediction of the cross section for e^+e^- -> c c-bar c c-bar, in lowest order in strong coupling constant, at sqrt{s}=10.6 GeV is about …
Indirect detection of dark matter via its annihilation products is a key technique in the search for dark matter in the form of weakly interacting massive particles (WIMPs). Strong constraints exist on the annihilation of WIMPs to highly visible Standard Model final states such as photons or charged particles. In the case of s-wave annihilation, this typically eliminates thermal relic cross sections for dark matter of mass below $\cal{O}$(10) GeV. However, such limits typically neglect the possibility that dark matter may annihilate to assumed invisible or hard-to-detect final states, such as …
Next-to-Leading-Order(NLO) QCD corrections to double J/psi production in e^+e^- annihilation at sqrt{s}=10.6 GeV are calculated. We find that they greatly decrease the cross section, with a K factor (NLO/LO) ranging from -0.31 to 0.25 depending on the renormalization scale. Although the renormalization scale dependence indicates a large uncertainty, when combined with the NLO QCD corrections to J/psi + eta_c production, it can explain why the double J/psi$ production could not be found at B factories while the J/psi + eta_c production could, despite the fact that cross section of the former is…
Next-to-Leading-Order(NLO) QCD corrections to J/jpsi plus eta_c production in e+e- annihilation at sqrt{s}=10.6 GeV is calculated in this paper, and an analytic result is obtained. By choosing proper physical parameters, a K factor (ratio of NLO to LO) of about 2, which is in agreement with the result in Ref.\cite{Zhang:2005ch}, is obtained. Our results show that the Next-Next-to-Leading-Order(NNLO) corrections might be quite large. The plot of the K-factor vs the center-of-mass energy sqrt{s} shows that it is more difficult to obtain a convergent result from the perturbative QCD without resum…
Charmonia with different transverse momentum $p_T$ usually comes from different mechanisms in the relativistic heavy ion collisions. This work tries to review the theoretical studies on quarkonium evolutions in the deconfined medium produced in p-Pb and Pb-Pb collisions. The charmonia with high $p_T$ are mainly from the initial hadronic collisions, and therefore sensitive to the initial energy density of the bulk medium. For those charmonia within $0.1<p_T<5$ GeV/c at the energies of Large Hadron Collisions (LHC), They are mainly produced by the recombination of charm and anti-charm quarks in …
The processes of D^{(*)}-mesons and Λ_c-baryons production in e^+e^--annihilation at 10.58 GeV and 91.18 GeV energies are concerned. At the 10.58 GeV energy the production of charmed particles via the B-mesons decays is also concerned. Scaling violation of the fragmentation functions is calculated at the NLL-accuracy. Nonperturbative fragmentation functions are retrieved from the experimental data of B-factories and are approximated by simple analytic expressions. It is proved, that the difference between nonperturbative fragmentation functions of mesons and baryons can be easily explained by …
We suggest searching for excited charmonium states in $e^+e^-$ annihilation via double charmonium production at $\sqrt{s}=10.6$ GeV with $B$ factories, based on a more complete leading order calculation including both QCD and QED contributions for various processes. In particular, for the C=+ states, the $χ_{c0}(nP)$ (n=2,3) and $η_c(mS)$ (m=3,4) may have appreciable potentials to be observed; while for the C=- states, the $η_ch_c$ production and especially the $χ_{c1}h_c$ production might provide opportunities for observing the $h_c$ with higher statistics in the future. A brief discussion fo…
In the Next-to-Minimal Supersymmetric Standard Model, neutralino dark matter can annihilate into a pair of photons through the exchange of a CP-odd Higgs boson in the s-channel. The CP-odd Higgs boson couples to two photons through a loop of dominantly higgsino-like charginos. We show that the parameter space of the NMSSM can accommodate simultaneously i) neutralino-like dark matter of a mass of about 130 GeV giving rise to a 130 GeV photon line; ii) an annihilation cross section of or larger than 10^{-27}cm^3s^{-1}; iii) a relic density in agreement with WMAP constraints; iv) a direct detecti…
The total cross section for electron-positron annihilation into hadrons is calculated in the region just below the B meson threshold. QCD corrections up to third order, quark mass effects, initial state radiation, the running of alpha_QED and the tails of the Upsilon resonances are included in the prediction. For given alpha_s the prediction is accurate to 0.5 percent. An experimental measurement with the corresponding precision would allow to determine alpha_s with high accuracy at intermediate energies.
We calculate the D-wave charmonium production in $e^+e^-$ annihilation at BELLE and BABAR at $\sqrt{s}=10.6$ GeV using the nonrelativistic QCD factorization formalism, including color singlet and color octet contributions. We analyze the contributions of various processes for $δ_J(J=1,2)$ production. We find that both the color singlet and color octet channels may give substantial contributions, and the production rates are estimated to be $σ(δ_1)\simeq 0.043-0.16pb$ and $σ(δ_2)\simeq 0.094-0.29pb$, which, however, are very sensitive to the choice of the color octet matrix elements of the D-wa…
We explore the possibility that the annihilation of dark matter (DM) is boosted due to enhanced substructure in the presence of primordial black holes (PBHs) which constitute a sub-component of DM. The PBHs can generate entropy fluctuations at the small scales which trigger early structure formation, and a large fraction of the whole DM can reside in these collapsed objects that formed at high redshift ($z\gtrsim 100$). Such early forming minihalos consequently possess higher densities than those in the conventional scenarios (without PBHs) and would be more resilient to tidal disruptions. Our…
In the Littlest Higgs model with $T$ parity (LHT), the $T$-odd heavy photon ($A_H$) is weakly interacting and can play the role of dark matter. We investigate the lower limit on the mass of $A_H$ dark matter under the constraints from Higgs data, EWPOs, $R_b$, Planck 2015 dark matter relic abundance, PandaX-II/LUX 2016 direct detections and LHC-8 TeV monojet results. We find that (1) Higgs data, EWPOs and $R_b$ can exclude the mass of $A_H$ up to 99 GeV. To produce the correct dark matter relic abundance, $A_H$ has to co-annihilate with $T$-odd quarks ($q_H$) or leptons ($\ell_H$); (2) the LUX…
It was recently reported that there may exist monochromatic $γ$-ray emission at $\sim 130$ GeV from the Galactic center in the Fermi Large Area Telescope data, which might be related with dark matter (DM) annihilation. In this work we carry out a comprehensive check of consistency of the results with the DM annihilation scenario, using the 3.7 yrs Fermi observation of the inner Galaxy, Galactic halo, clusters of galaxies and dwarf galaxies. The results found are as follows. 1) Very strong constraints on the DM annihilation into continuous $γ$-rays from the Galactic center are set, which are as…
Using recent CLEO III results for the cross section for $e^+e^- \to {\rm hadrons}$ at seven centre-of-mass energies between 6.964 and 10.538 GeV, we derive a value for the strong coupling constant $α_s(M_Z^2)=0.110_{-0.012}^{-0.010}{}_{-0.011}^{+0.010}$ where the uncertainties are uncorrelated and correlated, respectively. Our result differs significantly from the one derived by CLEO III, as a consequence of inclusion of quark mass effects and the proper matching between the effective theories with four and five flavours. Combining this new result with an analysis based on earlier cross sectio…
GeV-scale dark matter is an increasingly attractive target for direct detection, indirect detection, and collider searches. Its annihilation into hadronic final states produces a challenging zoo of light hadronic resonances. We update Herwig7 to study the photon and positron spectra from annihilation through a vector mediator. It covers dark matter masses between 250 MeV and 5 GeV and includes an error estimate.
Recent claims of a line in the Fermi-LAT photon spectrum at 130 GeV are suggestive of dark matter annihilation in the galactic center and other dark matter-dominated regions. If the Fermi feature is indeed due to dark matter annihilation, the best-fit line cross-section, together with the lack of any corresponding excess in continuum photons, poses an interesting puzzle for models of thermal dark matter: the line cross-section is too large to be generated radiatively from open Standard Model annihilation modes, and too small to provide efficient dark matter annihilation in the early universe. …
