We point out that the variance of net-baryon distribution normalized by the Skellam distribution baseline, $κ_2[B-\bar{B}]/\langle B+\bar{B}\rangle$, is sensitive to the possible modification of (anti)baryon yields due to $B\bar{B}$ annihilation in the hadronic phase. The corresponding measurements can thus place stringent limits on the magnitude of the $B\bar{B}$ annihilation and its inverse reaction. We perform Monte Carlo simulations of the hadronic phase in Pb-Pb collisions at the LHC via the recently developed subensemble sampler + UrQMD afterburner and show that the effect survives in net-proton fluctuations, which are directly accessible experimentally. The available experimental data of the ALICE Collaboration on net-proton fluctuations disfavors a notable suppression of (anti)baryon yields in $B\bar{B}$ annihilations predicted by the present version of UrQMD if only global baryon conservation is incorporated. On the other hand, the annihilations improve the data description when local baryon conservation is imposed. The two effects can be disentangled by measuring $κ_2[B+\bar{B}]/\langle B+\bar{B}\rangle$, which at the LHC is notably suppressed by annihilations but virtually unaffected by baryon number conservation.
The centrality dependence of the $p/π$ ratio measured by the ALICE Collaboration in 5.02 TeV Pb-Pb collisions indicates a statistically significant suppression with the increase of the charged particle multiplicity once the centrality-correlated part of the systematic uncertainty is eliminated from the data. We argue that this behavior can be attributed to baryon annihilation in the hadronic phase. By implementing the $B\bar{B} \leftrightarrow 5π$ reaction within a generalized partial chemical equilibrium framework, we estimate the annihilation freeze-out temperature at different centralities,…
The Born cross section and dressed cross section of $e^+e^-$ to $b\bar{b}$ and the total hadronic cross section in $e^+e^-$ annihilation in the bottomonium energy region are calculated based on the Rb values measured by the BaBar and Belle experiments. The data are used to calculate the vacuum polarization factors in the bottomonium energy region, and to determine the resonant parameters of the vector bottomonium(-like) states, the Y(10750), Upsilon(5S), and Upsilon(6S).
We study the $Y(4260)$ production mechanism in $e^+e^-$ annihilations in the framework of hadronic molecules and investigate the consequence of such a picture in different decay channels. In the hadronic molecule picture the $Y(4260)$ is described as a mixture state composed of a long-ranged $\bar{D}D_1(2420)+c.c.$ molecule state and a compact $c\bar{c}$ component. We show that the compositeness relation can still provide a reasonable constraint on the wavefunction renormalization parameter due to the dominance of the molecular component. Such a mechanism can be regarded as a natural consequen…
In the cold dark matter scenario, galactic dark matter halos are populated with a large number of smaller subhalos. Previous work has shown that dark matter annihilations in subhalos can generate a distinctive, non-Poisson signal in the gamma-ray photon counts probability distribution function (PDF). Here we show that the gamma-ray PDF also carries information about the velocity dependence of the dark matter annihilation cross section. After calculating the PDF assuming $s$-wave and Sommerfeld-enhanced annihilation, we perform a mock data analysis to illustrate how current and future observati…
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.
The installation of forward detectors in CMS and ATLAS turn the LHC to an effective photon-photon collider. The elastic scattering of the beam-protons via the emission of photons, which can be identified by tagging the intact protons in the forward detectors, provides a powerful diagnostic of the central production of new particles through photon-photon annihilation. In this letter we study the central production of dark matter particles and the potential of LHC to constrain the cross section of this process. By virtue of the crossing symmetry, this limit can immediately be used to constrain t…
Fluctuations of conserved charges allow to study the chemical composition of hadronic matter. A comparison between lattice simulations and the Hadron Resonance Gas (HRG) model suggested the existence of missing strange resonances. To clarify this issue we calculate the partial pressures of mesons and baryons with different strangeness quantum numbers using lattice simulations in the confined phase of QCD. In order to make this calculation feasible, we perform simulations at imaginary strangeness chemical potentials. We systematically study the effect of different hadronic spectra on thermodyna…
Recent radio observations have obtained stringent constraints for annihilating dark matter. In this article, we use the radio continuum spectral data of the Large Magellanic Cloud (LMC) to analyze the dark matter annihilation signals. We have discovered a slightly positive signal of dark matter annihilation with a $1.5σ$ statistical significance. The overall best-fit dark matter mass is $m_{\rm DM} \approx 90$ GeV, annihilating via $b\bar{b}$ channel. We have also constrained the $3σ$ lower limits of dark matter mass with the standard thermal dark matter annihilation cross section for the $e^+…
We construct an equation of state (EOS) for neutron stars by interpolating hadronic EOS at low density and quark EOS at high density. A hadronic model based on the parity doublet structure is used for hadronic matter and a quark model of Nambu--Jona-Lasinio type is for quark matter. We assume crossover between hadronic matter and quark matter in the the color-flavor locked phase. The nucleon mass of the parity doublet model has a mass associated with the chiral symmetry breaking, and a chiral invariant mass $m_0$ which is insensitive to the chiral condensate. The value of $m_0$ affects the nuc…
Institute for Theoretical Particle Physics and Cosmology (TTK), RWTH Aachen University（亚琛工业大学理论粒子物理与宇宙学研究所）
The interpretation of data from indirect detection experiments searching for dark matter annihilations requires computationally expensive simulations of cosmic-ray propagation. In this work we present a new method based on Recurrent Neural Networks that significantly accelerates simulations of secondary and dark matter Galactic cosmic ray antiprotons while achieving excellent accuracy. This approach allows for an efficient profiling or marginalisation over the nuisance parameters of a cosmic ray propagation model in order to perform parameter scans for a wide range of dark matter models. We id…
Constraining Gamma-ray Lines from Dark Matter Annihilation using Fermi-LAT and H.E.S.S. data
Universidade Federal do Rio Grande do Norte（北里奥格兰德联邦大学）；International Institute of Physics, Federal University of Rio Grande do Norte（北里奥格兰德联邦大学国际物理研究所）；Millennium Institute for Subatomic Physics at the High-Energy Frontier (SAPHIR) of ANID（智利国家研究与创新局高能前沿亚原子物理学千年研究所（SAPHIR））；Instituto de Física de São Carlos, Universidade de São Paulo（圣保罗大学圣卡洛斯物理研究所）
We consider a new technique for neutrino energy and topology reconstruction at DUNE. In particular, we show that when the direction of the incoming neutrino is known, one can use the measured directions of the outgoing leptonic and hadronic particles to reconstruct poorly-measured quantities, such as the hadronic cascade energy. We show that this alternative technique yields an energy resolution which is comparable to current reconstruction methods which sum measured energies. As a proof of concept we apply this new reconstruction method to a search for dark matter annihilation in the Sun. We …
We simultaneously incorporate two common extensions of the hadron resonance gas model, namely the addition of extra, unconfirmed resonances to the particle list and the excluded volume repulsive interactions. We emphasize the complementary nature of these two extensions and identify combinations of conserved charge susceptibilities that allow to constrain them separately. In particular, ratios of second-order susceptibilities like $χ_{11}^{BQ}/χ_2^B$ and $χ_{11}^{BS}/χ_2^B$ are sensitive only to the baryon spectrum, while fourth-to-second order ratios like $χ_4^B/χ_2^B$, $χ_{31}^{BS}/χ_{11}^{B…
Using Mueller's dipole formalism for deep inelastic scattering in QCD, we formulate and solve the evolution for the generating function for the multiplicities of the produced particles, in hadronic processes at high energy. The solution for the multiplicities satisfies Koba-Nielsen-Olesen (KNO) scaling, with good agreement with the recently re-analyzed data from the H1 experiment at HERA (DESY), and the old ALEPH data for hadronic $Z$ decay at LEP (CERN). The same scaling function with KNO scaling, carries to the hadronic multiplicities from jets in electron-positron annihilation. This agreeme…
We investigate the Glauber divergences in nonfactorizable annihilation amplitudes for two-body hadronic heavy meson decays in the $k_T$ factorization theorem at one-loop level. These divergences can be absorbed into the Glauber factors in the dominant kinematic regions of small parton momenta, which modify the interference between a nonfactorizable annihilation amplitude and other amplitudes by rotating it with a phase. We postulate that only the Glauber effect associated with a pion is significant, due to its special role as a $q\bar q$ bound state and as a pseudo Nambu-Goldstone boson simult…
Constraining Supersymmetric Dark Matter With Synchrotron Measurements
中性伴子暗物质（或其他暗物质候选者）的湮灭产生电子和正电子，以及其他标准模型态。这些粒子由于与银河磁场相互作用而发射出同步加速器光子。在这封信中，我们使用WMAP卫星的测量来限制这种同步辐射的强度，反过来，最轻的中性伴子的湮灭截面。我们发现这个约束比任何其他当前间接检测通道所提供的约束更严格。特别是，对于能量为100 GeV（500 GeV）的中性伴子，中性伴子湮灭的截面必须小于~ 3 x 10^-26 cm ^3/s（1 x 10^25 cm ^3/s）。对于银河系内部8千秒差距内完全平坦的暗物质分布的保守情况，约束的严格性大约是30倍。即使在这种保守的情况下，同步加速器的测量也强烈限制了早期宇宙中非热产生wino或higgsino中性伴子暗物质的可能性。
