arXiv subjects

Peng-Fei Yin

Publications and source records attributed to Peng-Fei Yin.

At least 91 records · Page 5Linked to original sources

arXiv2016

Searching for Singlino-Higgsino Dark Matter in the NMSSM

We study a simplified scenario in the next-to-minimal supersymmetric standard model with a split electroweak spectrum, in which only the singlino and higgsinos are light and other superpartners are decoupled. Serving as a dark matter candidate, a singlino-dominated neutralino $\tildeχ_1^0$ should have either resonant annihilation effects or sizable higgsino components to satisfy the observed relic abundance. The sensitivities of LHC searches and dark matter detection experiments are investigated. With an integrated luminosity of $30 (300) \mathrm{fb}^{-1}$, $3l + E_\mathrm{T} \!\!\!\!\!\!\!/ \;\;\;$and $2l + E_\mathrm{T} \!\!\!\!\!\!\!/ \;\;\;$ searches at the 13 (14) TeV LHC are expected to reach up to $m_{\tildeχ_1^0}\sim 150 (230) \mathrm{GeV}$ and $m_{\tildeχ_2^0,\tildeχ_1^{\pm}}\sim 320 (480) \mathrm{GeV}$. Near future dark matter direct and indirect detection experiments can cover some parameter regions where collider searches lose their sensitivities.

hep-ph↗

arXiv2016

The 750 GeV diphoton excess at the LHC and dark matter constraints

The recent reported 750 GeV diphoton excess at the 13 TeV LHC is explained in the framework of effective field theory assuming the diphoton resonance is a scalar (pseudoscalar) particle. It is found that the large production rate and the broad width of this resonance are hard to simultaneously explain if only visible final states are considered. Therefore an invisible decay channel to dark matter (DM) is strongly favored by the diphoton excess with a broad width, given a large coupling of the new scalar to DM. We set constraints on the parameter space in this scenario using the results from LHC Run 1, DM relic density, and DM direct and indirect detection experiments. We find that the DM searches can exclude a large portion of the parameter regions accounting for the diphoton excess with a broad width.

hep-ph↗

arXiv2016

Testing the electroweak phase transition and electroweak baryogenesis at the LHC and a circular electron-positron collider

We study the collider phenomenology of the electroweak phase transition and electroweak baryogenesis in the framework of the effective field theory. Our study shows that the effective theory using the dimension-6 operators can enforce strong first order phase transition and provide sizable CP violation to realize a successful electroweak baryogenesis. Such dimension-6 operators can induce interesting Higgs phenomenology that can be verified at colliders such as the LHC and the planning CEPC. We then demonstrate that this effective theory can originate from vector-like quarks and the triplet Higgs.

hep-ph↗

arXiv2016

Constraint on the velocity dependent dark matter annihilation cross section from Fermi-LAT observations of dwarf galaxies

The gamma-ray observation of dwarf spheroidal satellites (dSphs) is an ideal approach for probing the dark matter (DM) annihilation signature. The latest Fermi-LAT dSph searches have set stringent constraints on the velocity independent annihilation cross section in the small DM mass range, which gives very strong constraints on the scenario to explain the the AMS-02 positron excess by DM annihilation. However, the dSph constraints would change in the velocity dependent annihilation scenarios, because the velocity dispersion in the dSphs varies from that in the Milky Way. In this work, we use a likelihood map method to set constraints on the velocity dependent annihilation cross section from the Fermi-LAT observation of six dSphs. We consider three typical forms of the annihilation cross section, i.e. p-wave annihilation, Sommerfeld enhancement, and Breit-Wigner resonance. For the p-wave annihilation and Sommerfeld-enhancement, the dSph limits would become much weaker and stronger compared with those for the velocity independent annihilation, respectively. For the Breit-Wigner annihilation, the dSph limits would vary depending on the model parameters. We show that the scenario to explain the AMS-02 positron excess by DM annihilation is still viable in the velocity dependent cases.

astro-ph.HE↗

arXiv2016

Constraints on Dark Matter Annihilation/Decay from the Isotropic Gamma-Ray Background

In this work we study the constraints on dark matter (DM) annihilation/decay from the Fermi-LAT Isotropic Gamma-Ray Background (IGRB) observation. We consider the contributions from both extragalactic and galactic DM components. For DM annihilation, the evolutions of extragalactic DM halos are taken into account. We find that the IGRB constraints under some DM subhalo models can be comparable to those derived from the observations of dwarf spheroidal galaxies. We also use the IGRB results to constrain the parameter regions accounting for the latest AMS-02 electron-positron anomaly. We find that the majority of DM annihilation/decay channels are strongly disfavored by the latest Fermi-LAT IGRB observation; only DM annihilation/decay to $μ^+μ^-$ may be valid.

astro-ph.CO↗

arXiv2015

High Resolution Image Reconstruction Method for a Double-plane PET System with Changeable Spacing

Positron Emission Mammography (PEM) imaging systems with the ability in detection of millimeter-sized tumors were developed in recent years. And some of them have been well used in clinical applications. In consideration of biopsy application, a double-plane detector configuration is practical for the convenience of breast immobilization. However, the serious blurring effect in the double-plane system with changeable spacing for different breast size should be studied. Methods: We study a high resolution reconstruction method applicable for a double-plane PET system with a changeable detector spacing. Geometric and blurring components should be calculated at real time for different detector distance. Accurate geometric sensitivity is obtained with a tube area model. Resolution recovery is achieved by estimating blurring effects derived from simulated single gamma response information. Results: The results show that the new geometric modeling gives a more finite and smooth sensitivity weight in double-plane system. The blurring component yields contrast recovery levels that could not be reached without blurring modeling, as well as better visual recovery of the smallest spheres and better delineation of the structures in the reconstructed images. Statistical noise has lower variance at the voxel level with blurring modeling than without at matched resolution. Conclusion: In the distance-changeable double-plane PET, the finite resolution modeling during reconstruction achieves resolution recovery, without noise amplification.

physics.med-ph↗

arXiv2015

Implications for dark matter annihilation from the AMS-02 $\bar{p}/p$ ratio

The AMS-02 collaboration has just released the cosmic antiproton to proton ratio $\bar{p}/p$ with a high precision up to $\sim 450$ GeV. In this work, we calculate the secondary antiprotons generated by cosmic ray interactions with the interstellar medium taking into account the uncertainties from the cosmic ray propagation. The $\bar{p}/p$ ratio predicted by these processes shows some tension with the AMS-02 data in some regions of propagation parameters, but the excess is not significant. We then try to derive upper bounds on the dark matter annihilation cross section from the $\bar{p}/p$ data or signal regions favored by the data. It is shown that the constraint derived by the AMS-02 data is similar to that from Fermi-LAT observations of dwarf galaxies. The signal region for dark matter is usually required $m_χ\sim O(10)$ TeV and $\left<σv\right>\sim\mathcal{O}(10^{-23})~\cm^3~\sec^{-1}$.

hep-ph↗

arXiv2015

The interpretation for Galactic Center Excess and Electroweak Phase Transition in the NMSSM

The gamma-ray excess observed by the Fermi-LAT in the Galactic Center can be interpreted by the dark matter annihilation to $b\bar{b}$ via a light pseudoscalar in the NMSSM. It is interesting to note that the corresponding singlet scalar is useful to achieve a strongly first order phase transition required by the electroweak baryogenesis. In this paper, we investigate the possibility that the NMSSM model can simultaneously accommodate these two issues. The phase transition strength can be characterized by the vacua energy gap at zero temperature and be sufficiently enhanced by the tree-level effect in the NMSSM. We find that the annihilation of Singlino/Higgsino DM particles occurring close to the light pseudoscalar resonance is favored by the galactic center excess and the observed DM relic density, and a resulting small $κ/λ$ and a negative $A_κ$ can also lead to a successful strongly first order electroweak phase transition.

hep-ph↗

arXiv2015

Searches for dark matter signals in simplified models at future hadron colliders

We study the prospect of dark matter (DM) searches in the monojet channel at future $pp$ colliders with center-of-mass energies of 33, 50, and 100~TeV. We consider a class of simplified models in which a vector boson connecting DM particles to quarks is introduced. Comparing with studies in the effective field theory, the present framework gives more reasonable production rates and kinematics of the DM signatures. We estimate the sensitivities of future colliders with an integrated luminosity of 3 $ab^{-1}$ to the DM-induced monojet signature and show the parameter space that can be explored. The constraints from direct and indirect DM detection experiments are compared with the future collider sensitivities. We find that the future collider detection will be much more sensitive than the indirect detection for the vector interaction, and have better sensitivities than those of the direct detection by several orders of magnitude for the axial vector interaction.

hep-ph↗

arXiv2014

Attenuation correction with Region Growing Method used in the Positron Emission Mammography System

Positron Emission Mammography imaging system (PEMi) is a nuclear medicine diagnosis method dedicated for breast imaging. It provides a better resolution in detection of millimeter-sized breast tumors than whole-body PET. To address the requirement of semi-quantitative analysis with the radiotracer concentration map of the breast, a new attenuation correction method based on three-dimensional seeded region growing image segmentation (3DSRG-AC) solution was developed. The method gives a 3D connected region as the segmentation result instead of image slices. The continuously segmentation property makes this new method free of activity variation of breast tissues. Threshold value chosen is the key point for the segmentation process. The first valley of the grey level histogram of the reconstruction image is set as the lower threshold, which works fine in clinical application. Results show that attenuation correction for PEMi improves the image quality and the quantitative accuracy of radioactivity distribution determination. Attenuation correction also improves the probabilities to detect small and early breast tumors.

physics.med-ph↗

arXiv2014

Tau Portal Dark Matter models at the LHC

Motivated by the Galactic Center gamma-ray excess in the Fermi-LAT data, we study the signatures of a class of tau portal dark matter (DM) models where DM particles preferentially couple to tau leptons at the LHC. We consider the constraints from the DM direct detection and investigate the sensitivity of the LHC to di-tau plus missing energy signatures. We find that the LHC with a high luminosity of 3000 fb$^{-1}$ can test the tau portal DM models with fermionic mediators in the mass range of $120\sim450$ GeV.

hep-ph↗

arXiv2014

Status of Dark Matter Detection

The detection of dark matter has made great progresses in recent years. We give a brief review on the status and progress in dark matter detection, including the progresses in direct detection, collider detection at LHC and focus on the indirect detection. The results from PAMELA, ATIC, Fermi-LAT and relevant studies on these results are introduced. Then we give the progress on indirect detection of gamma rays from Fermi-LAT and ground based Cerenkov telescopes. Finally the detection of neutrinos and constraints on the nature of dark matter are reviewed briefly.

hep-ph↗

arXiv2014

Dark matter searches in the mono-$Z$ channel at high energy $e^+e^-$ colliders

We explore the mono-$Z$ signature for dark matter searches at future high energy $e^+e^-$ colliders. In the context of effective field theory, we consider two kinds of contact operators describing dark matter interactions with electroweak gauge bosons and with electron/positron, respectively. For five benchmark models, we propose kinematic cuts to distinguish signals from backgrounds for both charged leptonic and hadronic decay modes of the $Z$ boson. We also present the experimental sensitivity to cutoff scales of effective operators and compare it with that of the Fermi-LAT indirect search and demonstrate the gains in significance for the several configurations of polarized beams.

hep-ph↗

arXiv2013

Detecting interactions between dark matter and photons at high energy $e^+e^-$ colliders

We investigate the sensitivity to the effective operators describing interactions between dark matter particles and photons at future high energy $e^+e^-$ colliders via the $γ+ \slashed{E}$ channel. Such operators could be useful to interpret the potential gamma-ray line signature observed by the Fermi-LAT. We find that these operators can be further tested at $e^+ e^-$ colliders by using either unpolarized or polarized beams. We also derive a general unitarity condition for $2 \to n$ processes and apply it to the dark matter production process $e^+e^-\toχχγ$.

hep-ph↗

arXiv2013

Light stop/sbottom pair production searches in the NMSSM

In this work, we study the constraints on the scenario of light stops and sbottoms in the next-to-minimal supersymmetric standard model (NMSSM), especially by a 125 GeV Higgs boson discovery and the LHC bounds on supersymmetry. The constraints from dark matter detections are also taken into account. From the parameter scan, we find that the NMSSM can well accommodate a light Higgs boson around 125 GeV and decay patterns. We would like to stress that the LHC direct supersymmetry searches with b-tagging are very powerful and can set strong bounds on many NMSSM parameter points with light stops and sbottoms. We find $\tilde {t}\to b\tildeχ^+_1$ is a very promising channel for light stop detection if the mass splitting between $\tildeχ^+_1$ and $\tildeχ^0_1$ is very small. It is also pointed out that in order to close the parameter space of light stops and sbottoms, new search strategies for signal channels such as $p p \to {\tilde t_1} {\tilde t_1} \to t {\bar t} h h \tildeχ^0_1 \tildeχ^0_1$ and $p p \to {\tilde b_1} {\tilde b_1} \to t {\bar t} W^+ W^- \tildeχ^0_1 \tildeχ^0_1$ may be necessary.

hep-ph↗

arXiv2013

Pulsar interpretation for the AMS-02 result

The AMS-02 collaboration has just published a high precision measurement of the cosmic positron fraction $e^+/(e^- + e^+)$, which rises with energy from $\sim 5$ GeV to $\sim 350$ GeV. The result indicates the existence of primary electron/positron sources to account for the positron excess. In this work, we investigate the possibility that the nearby mature pulsars are the primary positron sources. By fitting the data we find that the positrons from a single nearby pulsar, such as Geminga or Monogem, with the spectral index $α\sim 2$ can interpret the AMS-02 result. We also investigate the possibility that high energy positrons are generated by multiple known pulsars in the ATNF catalogue. Such a scenario can also fit the AMS-02 data well. Future precise measurements of fine structures in the positron spectrum would be a support to the pulsar scenario.

astro-ph.HE↗

arXiv2012

Detecting light stop pairs in coannihilation scenarios at the LHC

In this work, we study the light stop pair signals at the large hadron collider (LHC) in three coannihilation scenarios. In order to yield the desired dark matter (DM) relic density, the neutralino can coannihilate with stop, chargino and stau, respectively. Signatures of the first scenario can be probed at the LHC via the associated jet production processes $pp \to j + {\tilde t} {\tilde t}^*$ by tagging an energetic mono-jet and a large missing transverse energy. The signatures of the other two scenarios can be searched via the pair production process $pp \to {\tilde t} {\tilde t}^*$ by tagging energetic b-jets in the final states and a large missing transverse energy. We find that the LHC results at 7 TeV with 5 $\mathrm{fb}^{-1}$ of data can exclude the stop mass up to 220, 380 and 220 GeV for these three scenarios, respectively. While the 20 $\mathrm{fb}^{-1}$ dataset at 8 TeV is considered, the LHC can be expected to exclude the stop mass up to 340, 430 and 370 GeV.

hep-ph↗

arXiv2012

Gamma-rays From Warm WIMP Dark Matter Annihilation

The weakly interacting massive particle (WIMP) often serves as a candidate for the cold dark matter, however when produced non-thermally it could behave like warm dark matter. In this paper we study the properties of the $γ$-ray emission from annihilation of WIMP dark matter in the halo of our own Milky-Way Galaxy with high resolution $N$-body simulations of a Milky-Way like dark matter halo, assuming different nature of WIMPs. Due to the large free-streaming length in the scenario of warm WIMPs, the substructure contend of the dark matter halo is significantly different from that of the cold WIMP counterpart, resulting in distinct predictions of the $γ$-ray signals from the dark matter annihilation. We illustrate these by comparing the predicted $γ$-ray signals from the warm WIMP annihilation to that of cold WIMPs. Pronounced differences from the subhalo skymap and statistical properties between two WIMP models are demonstrated. Due to the potentially enhanced cross section of the non-thermal production mechanism in warm WIMP scenario, the Galactic center might be prior for the indirect detection of warm WIMPs to dwarf galaxies, which might be different from the cold dark matter scenario. As a specific example we consider the non-thermally produced neutralino of supersymmetric model and discuss the detectability of warm WIMPs with Fermi $γ$-ray telescope.

astro-ph.HE↗