Kinetic mixing as the origin of a light dark-gauge-group scale

304

431

We present constraints on decaying and annihilating dark matter (DM) in the 4 keV to 10 GeV mass range, using published results from the satellites HEAO-1, INTEGRAL, COMPTEL, EGRET, and the Fermi Gamma-ray Space Telescope. We derive analytic expressions for the gamma-ray spectra from various DM decay modes, and find lifetime constraints in the range 10 24 − 10 28 sec, depending on the DM mass and decay mode. We map these constraints onto the parameter space for a variety of models, including a hidden photino that is part of a kinetically mixed hidden sector, a gravitino with Rparity violating decays, a sterile neutrino, DM with a dipole moment, and a dark pion. The indirect constraints on sterile-neutrino and hidden-photino DM are found to be more powerful than other experimental or astrophysical probes in some parts of parameter space. While our focus is on decaying DM, we also present constraints on DM annihilation to electron-positron pairs. We find that if the annihilation is p-wave suppressed, the galactic diffuse constraints are, depending on the DM mass and velocity at recombination, more powerful than the constraints from the Cosmic Microwave Background.

Section: Hidden Photinomentioning

confidence: 99%

“…Consider a supersymmetric hidden sector, with an additional U(1) d gauge group [4,7,[73][74][75][76]. We assume that the SM and hidden sector can interact with each other through gauge kinetic mixing [77,78],…”

Section: Hidden Photinomentioning

confidence: 99%

Constraining light dark matter with diffuse X-ray and gamma-ray observations

Essig

Kuflik

McDermott

et al. 2013

304

431

“…First, if the hidden sector contains a U(1) gauge field, loops involving heavy mediators can generate a marginal operator [7] L = χ d 2 θ W α W ′ α + h.c., (1.1) where W α and W ′ α are U(1) hypercharge and hidden sector field-strength superfields. This scenario has been extensively studied in literature, for example in [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. In this paper we discuss an alternative possibility: if both the visible and hidden sectors contain singlet chiral superfields, S and S ′ , then a marginal kinetic mixing operator L = ǫ d 4 θ S † S ′ + h.c., (1.2) can persist at low energies, no matter the scale of new physics, M * .…”

Section: Jhep11(2010)103mentioning

confidence: 99%

Singlet portal to the hidden sector

Cheung

Nomura

2010

Self Cite

Ultraviolet physics typically induces a kinetic mixing between gauge singlets which is marginal and hence non-decoupling in the infrared. In singlet extensions of the minimal supersymmetric standard model, e.g. the next-to-minimal supersymmetric standard model, this furnishes a well motivated and distinctive portal connecting the visible sector to any hidden sector which contains a singlet chiral superfield. In the presence of singlet kinetic mixing, the hidden sector acquires a light mass scale in the range 0.1 -100 GeV induced by electroweak symmetry breaking. In theories with R-parity conservation, superparticles produced at the LHC cascade decay into hidden sector particles. Since the hidden sector singlet couples to the visible sector via the Higgs sector, these cascades produce a Higgs boson in an order 0.01 -1 fraction of events. Furthermore, supersymmetric cascades typically produce highly boosted, low-mass hidden sector singlets decaying visibly, albeit with displacement, into the heaviest standard model particles which are kinematically accessible. We study experimental constraints on this broad class of theories, as well as the role of singlet kinetic mixing in direct detection of hidden sector dark matter. We also present related theories in which a hidden sector singlet interacts with the visible sector through kinetic mixing with right-handed neutrinos.

“…7 The maximum significance for the EM fraction for TYPE2 LJ is obtained by requiring a jet EM fraction to be less than 0.1; this provides 99.9% multi-jet background rejection. A similar optimization leads to requiring a jet width less than 0.1 (80% multi-jet background rejection).…”

Section: Jhep11(2014)088mentioning

confidence: 99%

“…The reconstruction efficiency is given for LJ with only one γ d as a function of the p T and of the transverse decay distance L xy of the γ d at the generation level. The efficiency 7 The jet width W is defined as:…”

Section: Lj Reconstruction Efficiencymentioning

confidence: 99%

Search for long-lived neutral particles decaying into lepton jets in proton-proton collisions at s = 8 $$ \sqrt{s}=8 $$ TeV with the ATLAS detector

Aad¹,

Abbott²,

Abdallah³

et al. 2014

109

Several models of physics beyond the Standard Model predict neutral particles that decay into final states consisting of collimated jets of light leptons and hadrons (socalled "lepton jets"). These particles can also be long-lived with decay length comparable to, or even larger than, the LHC detectors' linear dimensions. This paper presents the results of a search for lepton jets in proton-proton collisions at the centre-of-mass energy of √ s = 8 TeV in a sample of 20.3 fb −1 collected during 2012 with the ATLAS detector at the LHC. Limits on models predicting Higgs boson decays to neutral long-lived lepton jets are derived as a function of the particle's proper decay length. An extensively studied case is one in which the two sectors couple via the vector portal, in which a light hidden photon (dark photon, γ d ) mixes kinetically with the SM photon. If the hidden photon is the lightest state in the hidden sector, it decays back to SM particles with branching fractions that depend on its mass [6,8,9]. For the case in which the γ d kinetically mixes with hypercharge, one finds that , the kinetic mixing parameter, controls -1 - Keywords: Hadron-Hadron Scattering JHEP11(2014)088both the γ d decay branching fractions and lifetime. More generally, however, the branching fractions and lifetime are model-dependent and may depend on additional parameters.Due to their small mass, these particles are typically produced with a large boost and, due to their weak interactions, can have non-negligible lifetime. As a result one may expect, from dark photon decays, collimated jet-like structures containing pairs of electrons and/or muons and/or charged pions ("lepton jets", LJs) that can be produced far from the primary interaction vertex of the event (displaced LJs).Neutral particles which decay far from the interaction point into collimated final states represent a challenge both for the trigger and for the reconstruction capabilities of the LHC detectors. Collimated charged particles in the final state can be difficult to disentangle due to the limited granularity of the detector. Moreover, in the absence of information from the inner tracking system, it is necessary to use the muon spectrometer (MS) for the reconstruction of tracks which originate from a secondary decay far from the primary interaction vertex (IP).The high-resolution, high-granularity measurement capability of the ATLAS "air-core" MS is ideal for this type of search. In addition, the ATLAS inner tracking system can be used to define isolation criteria to significantly reduce, for decay vertices far from the interaction point, the otherwise overwhelming SM background from proton-proton collisions.The search for displaced LJs presented in this paper employs the full dataset collected by ATLAS during the 2012 run at √ s = 8 TeV, corresponding to an integrated luminosity of 20.3 fb −1 . Related searches for prompt LJs have been performed both at the Tevatron [10,11] and at the LHC [12][13][14][15]. Additional constraints on scenarios with hidden phot...