122688615
Search for Minimum Universal Extra Dimensions with Four Leptons Final State at CMS
In models where extra dimensions are accessible to all particles, a new set of particles is predicted with a mass spectrum that can mimic a SUSY scenario: all Standard Model particles will have so called Kaluza‐Klein partners. Recent studies of the CMS collaboration are presented on the sensitivity to searches for the minimum universal extra dimensions with a compactification scale up to 900 GeV−1, using the 4 leptons final state. These studies are based on detailed detector simulation, including all Standard Model backgrounds.
120493940
HEAVY STABLE CHARGED PARTICLE SEARCHES AT THE LHC
Several searches for heavy stable charged particles have recently been performed using data from $\sqrt{s} = 7 {\rm TeV}$pp collisions at the Large Hadron Collider (LHC). This review summarizes some of the theoretical and experimental motivations for such searches, and discusses searches for stable squarks, stable gluino, stable sleptons and multiply charged heavy stable particles with the CMS and ATLAS detectors.
119179797
Searching for high speed long-lived charged massive particles at the LHC
The conventional way to search for long-lived CHArged Massive Particles (CHAMPs) is to identify slow (small β) tracks using delayed time of flight and high ionization energy loss. But at the 7–14 TeV center of mass energy of the LHC, a CHAMP may be highly boosted (high β) and therefore look more like a minimum ionizing particle, while for high momentum muons (≳500 GeV/c) the radiative effect dominates energy deposition. This suggests a new strategy to search for CHAMPs at the LHC. Using energy deposition from different detector components, we construct a boosted decision tree discriminant to separate high momentum CHAMPs from high momentum muons. This method increases substantially the CHAMP discovery potential and it can be used to distinguish possible di-CHAMP or CHAMP–muon resonance models from di-muon resonance models. We illustrate the new method using a mGMSB model and a recently proposed di-CHAMP model and we give updated CHAMP mass limits for these two models using the results from a recent CDF CHAMP search.
119107849
Bose symmetry interference effects of 4 pi final states
We analyze the relative branching ratios of 4 pi final states pi(+)pi(-)pi(+)pi(-), pi(+)pi(-)pi(0)pi(0), and pi(0)pi(0)pi(0)pi(0), from various resonances with J(PC) = 0(++), 0(-+), 2(++). We find that in some cases the interference effects due to Bose symmetry make their ratios obviously different from the naive counting values without these effects. The results allow an accurate estimate of the 4 pi branching ratios of relevant resonances when only one (or two) modes are measured in a given experiment.
119285071
Dark matter coupling to electroweak gauge and Higgs bosons: An effective field theory approach
Abstract If dark matter is a new species of particle produced in the early universe as a cold thermal relic (a weakly-interacting massive particle—WIMP), its present abundance, its scattering with matter in direct-detection experiments, its present-day annihilation signature in indirect-detection experiments, and its production and detection at colliders, depend crucially on the WIMP coupling to standard-model (SM) particles. It is usually assumed that the WIMP couples to the SM sector through its interactions with quarks and leptons. In this paper we explore the possibility that the WIMP coupling to the SM sector is via electroweak gauge and Higgs bosons. In the absence of an ultraviolet-complete particle-physics model, we employ effective field theory to describe the WIMP–SM coupling. We consider both scalars and Dirac fermions as possible dark-matter candidates. Starting with an exhaustive list of operators up to dimension 8, we present detailed calculation of dark-matter annihilations to all possible final states, including γγ, γ Z , γ h , ZZ , Zh , W + W − , hh , and f f ¯ , and demonstrate the correlations among them. We compute the mass scale of the effective field theory necessary to obtain the correct dark-matter mass density, and well as the resulting photon line signals.
125296132
Phase transitions and the perfectness of fluids
118981397
125 GeV Higgs boson decays in the μ from ν supersymmetric standard model
Recently the ATLAS and CMS Collaborations have reported significant events that are attributed to the neutral Higgs boson with mass around 125 GeV. In this work, we investigate the signals of the Higgs boson decay channels $h\rightarrow\gamma\gamma$, $h\rightarrow VV^*$ ($V=Z,W$), and $h\rightarrow f\bar{f}$ ($f=b,\tau$) in the $\mu$ from $\nu$ supersymmetric standard model ($\mu\nu$SSM). In the numerical results, we show the light stop and stau effects on the signal strengths for the 125 GeV Higgs boson decay channels in the $\mu\nu$SSM, which can account for the updated experimental data on Higgs.
32811554
Model-independent results for SU(3) violation in light-cone distribution functions.
Using chiral symmetry we investigate the leading SU(3) violation in light-cone distribution functions phi(M)(x) of the pion, kaon, and eta. It is shown that terms nonanalytic in the quark masses do not affect the shape, and only appear in the decay constants. Predictive power is retained including the leading analytic m(q) operators. With the symmetry violating corrections we derive useful model-independent relations between phi(pi),phi(eta),phiK+(,K0), and phiK(0)(,K-). Using the soft-collinear effective theory we discuss how factorization generates the subleading chiral coefficients.
56112288
Residue theorem and summing over Kaluza-Klein excitations
Applying the equations of motion together with corresponding boundary conditions of bulk profiles at infrared and ultraviolet branes, we verify some lemmas on the eigenvalues of Kaluza-Klein modes in extension of the standard model with a warped extra dimension and the custodial symmetry SU(3){sub c}xSU(2){sub L}xSU(2){sub R}xU(1){sub X}xP{sub LR}. Using the lemmas and performing properly analytic extensions of bulk profiles, we present the sufficient condition for a convergent series of Kaluza-Klein excitations and sum over the series through the residue theorem. The method can also be applied to sum over the infinite series of Kaluza-Klein excitations in a universal extra dimension. Furthermore, we analyze the possible connection between the propagators in five-dimensional full theory and the product of bulk profiles with corresponding propagators of exciting Kaluza-Klein modes in four-dimensional effective theory, and recover some relations presented in the literature for warped and universal extra dimensions, respectively. As an example, we present the correction from new physics to the branching ratio of B{yields}X{sub s{gamma}} to the order O({mu}{sub EW}{sup 2}/{Lambda}{sub KK}{sup 2}) in extension of the standard model with a warped extra dimension and the custodial symmetry, where {Lambda}{sub KK} denotes the energy scale of low-lying Kaluza-Klein excitations and {mu}{sub EW}more » denotes the electroweak energy scale.« less