A
bstract
This work studies the self-interacting dark matter (SIDM) scenario in the general NMSSM and beyond, where the dark matter is a Majorana fermion and the force mediator is a scalar boson. An ...improved analytical expression for the dark matter (DM) self-interacting cross section which takes into account the Born level effects is proposed. Due to the large couplings and light mediator in SIDM scenario, the DM/mediator will go through multiple branchings if they are produced with high energy. Based on the Monte Carlo simulation of the showers in the DM sector, we obtain the multiplicities and the spectra of the DM/mediator from the Higgsino production and decay at the LHC for our benchmark points.
A
bstract
Based on the jet image approach, which treats the energy deposition in each calorimeter cell as the pixel intensity, the Convolutional neural network (CNN) method has been found to achieve ...a sizable improvement in jet tagging compared to the traditional jet substructure analysis. In this work, the Mask R-CNN framework is adopted to reconstruct Higgs jets in collider-like events, with the effects of pileup contamination taken into account. This automatic jet reconstruction method achieves higher efficiency of Higgs jet detection and higher accuracy of Higgs boson four-momentum reconstruction than traditional jet clustering and jet substructure tagging methods. Moreover, the Mask R-CNN trained on events containing a single Higgs jet is capable of detecting one or more Higgs jets in events of several different processes, without apparent degradation in reconstruction efficiency and accuracy. The outputs of the network also serve as new handles for the
t
t
¯
background suppression, complementing to traditional jet substructure variables.
The quirk signal at FASER and FASER 2 Li, Jinmian; Pei, Junle; Ran, Long jie ...
The journal of high energy physics,
12/2021, Letnik:
2021, Številka:
12
Journal Article
Recenzirano
Odprti dostop
A
bstract
We study FASER and FASER 2 sensitivities to the quirk signal by simulating the motions of quirks that are travelling through several infrastructures from the ATLAS interaction point to the ...FASER (2) detector. The ionization energy losses for a charged quirk travelling in different materials are treated carefully. We calculate the expected numbers of quirk events that can reach the FASER (2) detector for an integrated luminosity of 150 (3000) fb
−
1
. Scenarios for quirks with four different quantum numbers, and different masses and confinement scales are studied.
A
bstract
We consider inelastic dark matter scenarios with dark photon mediator and a dark Higgs boson. The dark Higgs boson spontaneously breaks the gauge symmetry associated with the dark photon, ...and gives the mass to the dark photon and the mass difference to dark particles. Such a dark Higgs boson can decay into the dark particles and hence can be another source of the dark particles at collider experiments. We analyze the sensitivity to decays of the excited state into the dark matter and charged particles at the FASER 2 experiment in fermion and scalar inelastic dark matter scenarios. We consider two mass spectra as illustrating examples in which the excited state can be produced only through the decay of dark Higgs boson. We show that unprobed parameter region can be explored in fermion dark matter scenario for the illustrating mass spectra.
A gauge invariant UV-completion for singlet fermion DM interacting with the standard model (SM) particles involves a new singlet scalar. Therefore the model contains two scalar mediators, mixtures of ...the SM Higgs boson and a singlet scalar boson. Collider phenomenology of the interference effect between these two scalar propagators is studied in this work. This interference effect can be either constructive or destructive in the DM production cross section depending on both singlet scalar and DM masses, and it will soften the final state jets in the full mass region. Applying the CMS mono-jet search to our model, we find the interference effect plays a very important role in the DM search sensitivity, and the DM production cross section of our model is more than one order of magnitude below the LHC sensitivity at current stage.
We study the dark matter (DM) discovery prospect and its spin discrimination in the theoretical framework of gauge invariant and renormalizable Higgs portal DM models at the ILC with
s
=
500
GeV. In ...such models, the DM pair is produced in association with a
Z
boson. In the case of the singlet scalar DM, the mediator is just the SM Higgs boson, whereas for the fermion or vector DM there is an additional singlet scalar mediator that mixes with the SM Higgs boson, which produces significant observable differences. After careful investigation of the signal and backgrounds both at parton level and at detector level, we find the signal with hadronically decaying
Z
boson provides a better search sensitivity than the signal with leptonically decaying
Z
boson. Taking the fermion DM model as a benchmark scenario, when the DM-mediator coupling
g
χ
is relatively small, the DM signals are discoverable only for benchmark points with relatively light scalar mediator
H
2
. The spin discriminating from scalar DM is always promising, while it is difficult to discriminate from vector DM. As for
g
χ
approaching the perturbative limit, benchmark points with the mediator
H
2
in the full mass region of interest are discoverable. The spin discriminating aspects from both the scalar and the fermion DM are quite promising.
On naturalness of the MSSM and NMSSM Kang, Zhaofeng; Li, Jinmian; Li, Tianjun
The journal of high energy physics,
11/2012, Letnik:
2012, Številka:
11
Journal Article
Recenzirano
Odprti dostop
A
bstract
With a bottom-up approach, we consider naturalness in the MSSM and NMSSM. Assuming the light stops, the LHC gluino search implies that the degree of fine tuning in both models is less than ...2.5%. Taking the LHC hints for the SM-like Higgs boson mass
m
h
~ 125 GeV seriously, we find that naturalness will favor the NMSSM. We study the Higgs boson mass for several scenarios in the NMSSM: (1) A large λ and the doublet-singlet Higgs boson mixing effect pushing upward or pulling downward
m
h
. The former case can readily give the di-photon excess of the Higgs boson decay whereas the latter case can not. However, we point out that the former case has a new large fine-tuning related to strong λ−RGE running effect and vacuum stability. (2) A small λ and the mixing effect pushing
m
h
upward. Naturalness status becomes worse and no significant di-photon excess can be obtained. In these scenarios, the lightest supersymmetric particle (LSP) as a dark matter candidate is strongly disfavored by the XENON100 experiment. Even if the LSP can be a viable dark matter candidate, there does exist fine-tuning. The above naturalness evaluation is based on a high mediation scale for supersymmetry breaking, whereas for a low mediation scale, fine-tuning can be improved by about one order.
Abstract Multi-component dark matter scenarios are studied in the model with U(1) X dark gauge symmetry that is broken into its product subgroup Z 2 × Z 3 á la Krauss-Wilczek mechanism. In this ...setup, there exist two types of dark matter fields, X and Y, distinguished by different Z 2 × Z 3 charges. The real and imaginary parts of the Z 2-charged field, X R and X I , get different masses from the U(1) X symmetry breaking. The field Y, which is another dark matter candidate due to the unbroken Z 3 symmetry, belongs to the Strongly Interacting Massive Particle (SIMP)-type dark matter. Both X I and X R may contribute to Y’s 3 → 2 annihilation processes, opening a new class of SIMP models with a local dark gauge symmetry. Depending on the mass difference between X I and X R , we have either two-component or three-component dark matter scenarios. In particular two- or three-component SIMP scenarios can be realised not only for small mass difference between X and Y, but also for large mass hierarchy between them, which is a new and unique feature of the present model. We consider both theoretical and experimental constraints, and present four case studies of the multi-component dark matter scenarios.
A
bstract
We study the probing prospects of cosmic ray boosted dark matter (DM) in the framework of simplified electron-philic dark photon model. Focusing on the dark matter and dark photon masses ...around keV ~ MeV scale, we consider the bounds obtained from the XENON1T and Super-K experiments. The electron bound state effects are treated carefully in calculating the XENON1T constraint. As for the detection at neutrino detector where the energy threshold is relatively higher, the large logarithmic effects induced by the scale hierarchy between the masses and momentum transfer are considered by introducing the DM parton distribution function (PDF). The logarithmic effects will reduce the electron recoil rate for DM scattering in neutrino detectors. Moreover, we find the DUNE and JUNO experiments provide high sensitivities for probing the dark photon component in the DM PDF through the dark Compton process. We also check the Bullet Cluster constraint on the DM self-scattering cross section.
The quirk trajectory Li, Jinmian; Li, Tianjun; Pei, Junle ...
The European physical journal. C, Particles and fields,
07/2020, Letnik:
80, Številka:
7
Journal Article
Recenzirano
Odprti dostop
We for the first time obtain the analytical solution for the quirk equation of motion in an approximate way. Based on it, we study several features of quirk trajectory in a more precise way, ...including quirk oscillation amplitude, number of periods, as well as the thickness of quirk pair plane. Moreover, we find an exceptional case where the quirk crosses at least one of the tracking layers repeatedly. Finally, we consider the effects of ionization energy loss and fixed direction of infracolor string for a few existing searches.
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