104 research outputs found

### Interpretations of galactic center gamma-ray excess confronting the PandaX-II constraints on dark matter-neutron spin-dependent scatterings in the NMSSM

The Weakly Interacting Massive Particle (WIMP) has been one of the most
attractive candidates for Dark Matter (DM), and the lightest neutralino
($\widetilde{\chi}^0_1$) in the Next-to-Minimal Supersymmetric Standard Model
(NMSSM) is an interesting realization of WIMP. The Galactic Center Excess (GCE)
can be explained by WIMP DM annihilations in the sky. In this work we consider
the $Z_3$-NMSSM where the singlet $S$ and Singlino $\widetilde{S}^0$ components
play important roles in the Higgs and DM sector. Guided by our analytical
arguments, we perform a numerical scan over the NMSSM parameter space for the
GCE explanation by considering various observables such as the Standard Model
(SM) Higgs data measured by the ATLAS and CMS experiments, and the $B$-physics
observables $BR(B_s\rightarrow X_s\gamma)$ and $BR(B_s\rightarrow \mu^+\mu^-)$.
We find that the correlation between the coupling $C_{A_1 b\bar{b}}$ in
$\langle \sigma_{b\bar{b}} v \rangle _{0}$ and the coupling $C_{Z
\widetilde{\chi}^0_1 \widetilde{\chi}^0_1}$ in DM-neutron Spin Dependent (SD)
scattering rate $\sigma^{SD}_{\widetilde{\chi}^0_1-N}$ makes all samples we
obtain for GCE explanation get excluded by the PandaX-II results. Although the
DM resonant annihilation scenarios may be beyond the reach of our analytical
approximations and scan strategy, the aforementioned correlation can be a
reasonable motivation for future experiments such as PandaX-nT to further test
the NMSSM interpretation of GCE.Comment: 11 pages, 4 figures, meeting the published version by EPJ

### Explanation of the ATLAS Z-peaked excess by squark pair production in the NMSSM

The ATLAS collaboration recently reported a $3\sigma$ excess in the
leptonic-$Z+jets+E_{T}^{miss}$ channel. We intend to interpret this excess by
squark pair production in the Next-to-Minimal Supersymmetric Standard Model
(NMSSM). The decay chain we employ is $\tilde{q} \to q \tilde{\chi}_2^0 \to q
\tilde{\chi}_1^0 Z$, where $\tilde{\chi}_1^0$ and $\tilde{\chi}_2^0$ denote the
lightest and the next-to-lightest neutralinos with singlino and bino as their
dominant components respectively. Our simulations indicate that after
considering the constraints from the ATLAS searches for $jets + E_{T}^{miss}$
signal the central value of the excess can be obtained for $m_{\tilde{q}}
\lesssim 1.2 {\rm TeV}$, and if the constraint from the CMS on-$Z$ search is
further considered, more than 10 signal events are still attainable for
$m_{\tilde{q}} \lesssim 750 {\rm GeV}$. Compared with the interpretation by
gluino pair production, the squark explanation allows for a significantly wider
range of $m_{\tilde{q}}$ as well as a less compressed SUSY mass spectrum. We
also show that the squark explanation will be readily tested at the initial
stage of the 14 TeV LHC.Comment: 19 pages, 4 figure

### EasyScan_HEP: a tool for connecting programs to scan the parameter space of physics models

We present an application, EasyScan_HEP, for connecting programs to scan the
parameter space of high energy physics models using various sampling
algorithms. We develop EasyScan_HEP according to the principle of flexibility
and usability. EasyScan_HEP allows us to connect different programs that
calculate physical observables, and apply constraints by one human-readable
configuration file. All programs executed through command lines can be
connected to EasyScan_HEP by setting input and output parameters of the
programs. The current version offers the sampling algorithms of Random, Grid,
Markov chain Monte Carlo and MultiNest. We also implement resuming, post
process and quick analyses

### Explanation of the ATLAS Z-peaked excess in the NMSSM

Recently the ATLAS collaboration reported a $3\sigma$ excess in the
leptonic-$Z+jets+E_{T}^{miss}$ channel. This may be interpreted in the
Next-to-Minimal Supersymmetric Standard Model (NMSSM) by gluino pair production
with the decay chain $\tilde{g} \to q \bar{q} \tilde{\chi}_2^0 \to q \bar{q} Z
\tilde{\chi}_1^0$, where $\tilde{\chi}_1^0$ and $\tilde{\chi}_2^0$ denote the
lightest and the next-to-lightest neutralinos with singlino and bino as their
dominant components respectively. After exploring the relevant parameter space
of the NMSSM by considering the constraints from the ATLAS searches for $jets +
E_{T}^{miss}$ signals, we conclude that the NMSSM is able to explain the excess
at $1 \sigma$ level with the number of the signal events reaching its measured
central value in optimal cases, and the best explanation comes from a
compressed spectrum such as $m_{\tilde{g}} \simeq 650 {\rm GeV}$,
$m_{\tilde{\chi}_2^0} \simeq 565 {\rm GeV}$ and $m_{\tilde{\chi}_1^0} \simeq
465 {\rm GeV}$. We also check the consistency of the ATLAS results with the
null result of the CMS on-$Z$ search. We find that under the CMS limits at
$95\%$ C.L., the event number of the ATLAS on-$Z$ signal can still reach 11 in
our scenario, which is about $1.2 \sigma$ away from the measured central value.Comment: 18 pages, 2 figure

### Interpreting The 750 GeV Diphoton Excess Within Topflavor Seesaw Model

We propose to interpret the 750 GeV diphoton excess in a typical topflavor
seesaw model. The new resonance X can be identified as a CP-even scalar
emerging from a certain bi-doublet Higgs field. Such a scalar can couple to
charged scalars, fermions as well as heavy gauge bosons predicted by the model,
and consequently all of the particles contribute to the diphoton decay mode of
the X. Numerical analysis indicates that the model can predict the central
value of the diphoton excess without contradicting any constraints from 8 TeV
LHC, and among the constraints, the tightest one comes from the Z \gamma
channel, \sigma_{8 {\rm TeV}}^{Z \gamma} \lesssim 3.6 {\rm fb}, which requires
\sigma_{13 {\rm TeV}}^{\gamma \gamma} \lesssim 6 {\rm fb} in most of the
favored parameter space.Comment: Major changes, 17 pages, 4 figure, typos corrected, calculation
details adde

### Pair production of 125 GeV Higgs boson in the SM extension with color-octet scalars at the LHC

Although the Higgs boson mass and single production rate have been determined
more or less precisely, its other properties may deviate significantly from its
predictions in the standard model (SM) due to the uncertainty of Higgs data. In
this work we study the Higgs pair production at the LHC in the Manohar-Wise
model, which extends the SM by one family of color-octet and isospin-doublet
scalars. We first scanned over the parameter space of the Manohar-Wise model
considering exprimental constraints and performed fits in the model to the
latest Higgs data by using the ATLAS and CMS data separately. Then we
calculated the Higgs pair production rate and investigated the potential of its
discovery at the LHC14. We conclude that: (i) Under current constrains
including Higgs data after Run I of the LHC, the cross section of Higgs pair
production in the Manohar-Wise model can be enhanced up to even $10^3$ times
prediction in the SM. (ii) Moreover, the sizable enhancement comes from the
contributions of the CP-odd color-octet scalar $S^A_I$. For lighter scalar
$S^A_I$ and larger values of $|\lambda_I|$, the cross section of Higgs pair
production can be much larger. (iii) After running again of LHC at 14 TeV, most
of the parameter spaces in the Manohar-Wise model can be test. For an
integrated luminosity of 100 fb$^{-1}$ at the LHC14, when the normalized ratio
$R=10$, the process of Higgs pair production can be detected.Comment: 13 pages, 4 figure

### Sneutrino DM in the NMSSM with inverse seesaw mechanism

In supersymmetric theories like the Next-to-Minimal Supersymmetric Standard
Model (NMSSM), the lightest neutralino with bino or singlino as its dominant
component is customarily taken as dark matter (DM) candidate. Since light
Higgsinos favored by naturalness can strength the couplings of the DM and thus
enhance the DM-nucleon scattering rate, the tension between naturalness and DM
direct detection results becomes more and more acute with the improved
experimental sensitivity. In this work, we extend the NMSSM by inverse seesaw
mechanism to generate neutrino mass, and show that in certain parameter space
the lightest sneutrino may act as a viable DM candidate, i.e. it can annihilate
by multi-channels to get correct relic density and meanwhile satisfy all
experimental constraints. The most striking feature of the extension is that
the DM-nucleon scattering rate can be naturally below its current experimental
bounds regardless of the higgsino mass, and hence it alleviates the tension
between naturalness and DM experiments. Other interesting features include that
the Higgs phenomenology becomes much richer than that of the original NMSSM due
to the relaxed constraints from DM physics and also due to the presence of
extra neutrinos, and that the signatures of sparticles at colliders are quite
different from those with neutralino as DM candidate.Comment: 33 page

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