115179431
Closing the Wedge with 300 fb$^{-1}$ and 3000 fb$^{-1}$ at the LHC: A Snowmass White Paper
The discovery of a Higgs boson at the LHC begins the era of directly measuring the mechanism of electroweak symmetry breaking (EWSB). Searching for extensions of the Standard Model (SM) EWSB sector at the LHC is of vital importance. An important extension of the SM with an extended EWSB sector is the Minimal Supersymmetric Standard Model (MSSM). In this white paper, we extend current ATLAS and CMS bounds on direct searches for the heavy MSSM neutral Higgs bosons to 300 fb^-1 and 3000 fb^-1 of data at the LHC. In particular we focus on the \tau^+\tau^- channel and the pseudoscalar decay to light Higgs boson and Z, with additional discussion on how to further close the wedge.
18105043
Chiral couplings of W ′ and top quark polarization at the LHC
If a TeV-scale charged gauge boson (W') is discovered at the Large Hadron Collider (LHC), it will become imperative to determine its chiral couplings to standard model (SM) fermions in order to learn about the underlying theory containing the W'. We describe the reconstruction of the tb decay mode of the W' at the LHC, and identify various kinematic observables such as the angular distributions of the top quark and the lepton resulting from top decay that can be used to disentangle the chiral couplings of the W' to SM fermions. We demonstrate by presenting analytical expressions, numerical simulations, as well as intuitive illustrations for these observables at the LHC that among the SM fermions, the polarized top quark can most directly probe the chirality of such couplings.
119256327
Exploring resonant di-Higgs boson production in the Higgs singlet model
We study the enhancement of the di-Higgs production cross section resulting from the resonant decay of a heavy Higgs boson at hadron colliders in a model with a Higgs singlet. This enhancement of the double Higgs production rate is crucial in understanding the structure of the scalar potential and we determine the maximum allowed enhancement such that the electroweak minimum is a global minimum. The di-Higgs production enhancement can be as large as a factor of $\ensuremath{\sim}18(13)$ for the mass of the heavy Higgs around 270(420) GeV relative to the Standard Model rate at 14 TeV for parameters corresponding to a global electroweak minimum.
116539757
Cosmological and Astrophysical Constraints on Tensor Unparticles
We calculate cosmological and astrophysical bounds on the couplings between standard model fields and tensor unparticles. The present day density of tensor unparticles from neutrino-neutrino and photon-photon annihilation is calculated. Also, the supernovae volume energy loss rates from electron-positron and photon-photon annihilation to tensor unparticles are calculated. The constraints from matter density and supernovae volume energy loss rates from photon-photon annihilation are on the same order of magnitude, while the bounds from supernovae volume energy loss rates from electron-positron annihilation are an order of magnitude lower. We find the couplings between standard model fields and tensor unparticles are at least an order of magnitude lower than those used for previous studies of tensor unparticle collider phenomenology.
5632236
Right-Handed Neutrinos as the Origin of the Electroweak Scale
The insular nature of the Standard Model may be explained if the Higgs mass parameter is only sensitive to quantum corrections from physical states. Starting from a scale-free electroweak sector at tree-level, we postulate that quantum effects of heavy right-handed neutrinos induce a mass term for a scalar weak doublet that contains the dark matter particle. In turn, below the scale of heavy neutrinos, the dark matter sector sets the scale of the Higgs potential. We show that this framework can lead to a Higgs mass that respects physical naturalness, while also providing a viable scalar dark matter candidate, realistic light neutrino masses, and the baryon asymmetry of the Universe via leptogenesis. The proposed scenario can remain perturbative and stable up to the Planck scale, thereby accommodating simple extensions to include a high scale (2\times 10^{16} GeV) inflationary sector, implied by recent measurements. In that case, our model typically predicts that the dark matter scalar is close to 1 TeV in mass and could be accessible in near future direct detection experiments.
53309074
Dark matter from hidden forces
We examine the possibility that dark matter may be the manifestation of dark forces of a hidden sector, i.e. "Dark Force = Dark Matter." As an illustrative and minimal example we consider the hidden SU(2)_h x U(1)_h gauge group. The hidden dynamics is indirectly coupled to the Standard Model (SM) through kinetic mixing of U(1)_h with the U(1)_Y of hypercharge. We assume a hidden symmetry breaking pattern analogous to that of the SM electroweak symmetry, augmented with an extra scalar that allows both the "hidden Z boson" Z_h and the "hidden photon" \gamma_h to be massive. The "hidden W" bosons W_h are dark matter in this scenario. This setup can readily accommodate a potential direct detection signal for dark matter at ~10 GeV from CDMSII-Si data. For some choices of parameters, the model can lead to signals both in "dark matter beam" experiments, from Z_h\to W_h W_h, as well as in experiments that look for visible signals of dark photons, mediated by \gamma_h. Other possible phenomenological consequences are also briefly discussed.
34755903
The star formation rate at redshift one: Hα spectroscopy with CIRPASS
We have conducted an Ha survey of 38 0.77 ≤ z ≤ 1 galaxies over ∼100 arcmin 2 of the Hubble Deep Field-North and Flanking Fields, to determine star formation rates (SFRs), with the near-IR multi-object spectrograph Cambridge Infrared Panoramic Survey Spectrograph (CIRPASS) on the William Herschel Telescope (WHT). This represents the first successful application of this technique to observing high-redshift galaxies. Stacking the spectra in the rest frame to infer a total SFR for the field, we find a lower limit (uncorrected for dust reddening) on the SFR density at redshift z = 1 of 0.04 M ⊙ yr -1 Mpc -3 . This implies rapid evolution in the SFR density from z = 0 to 1 which is proportional to (1 + z) 3.1 .
118886319
NIR Spectroscopy of Star-Forming Galaxies at z ∼ 1.4 with Subaru/FMOS: The Mass–Metallicity Relation
We present near-infrared spectroscopic observations of star-forming galaxies at z � 1.4 with FMOS on the Subaru Telescope. We observed K-band selected galaxies in the SXDS/UDS fields with K � 23.9mag, 1.2 � zph � 1.6, M� � 10 9:5 Mˇ, andexpectedF(H˛) � 10 � 16 ergs � 1 cm � 2 ; 71objectsin the sample havesignificantdetections of H˛. For these objects, excluding possible AGNs, identified from the BPT diagram, gas-phase metallicities were obtained from the [NII]/H˛ line ratio. The sample is split into three stellar-mass bins, and the spectra are stacked in each stellar-mass bin. The mass‐metallicity relation obtained at z � 1.4 is located between those at z � 0.8 and z � 2.2. We constrain the intrinsic scatter to be � 0.1dex, or larger in the mass‐metallicity relation at z � 1.4; the scatter may be larger at higher redshifts. We found trends that the deviation from the mass‐metallicity relation depends on the SFR (Star-formation rate) and the half light radius: Galaxies with higher SFR and larger half light radii show lower metallicities at a given stellar mass. One possible scenario for the trends is the infall of pristine gas accreted from IGM, or through merger events. Our data points show larger scatter than the fundamental metallicity relation (FMR) at z � 0.1, and the averagemetallicities slightly deviate fromthe FMR. The compilationof the mass‐ metallicity relations at z � 3t oz � 0.1 shows that they evolve smoothly from z � 3t oz � 0 without changing the shape so much, except for the massive part at z � 0.
119346714
Star Formation at Redshift One: Preliminary results from an H-alpha Survey
We present the first successful demonstration of multi-object near-infrared spectroscopy on high redshift galaxies. Our objective is to address the true star formation history of the universe at z~1, a crucial epoch which some have suggested is the peak of star formation activity. By using H-alpha -the same robust star formation indicator used at low-z - redshifted into the J- and H-bands, we can trace star formation without the systematic uncertainties of different calibrators, or the extreme dust extinction in the rest-UV, which have plagued previous efforts. We are using the instrument CIRPASS (the Cambridge Infra-Red PAnoramic Survey Spectrograph), in multi-object mode, which has been successfully demonstrated on the Anglo-Australian Telescope (AAT) and the William Herschel Telescope (WHT). CIRPASS has 150 fibres deployable over \~40arcmin on the AAT and ~15arcmin on the WHT. Here we present preliminary results from one of our fields observed with the WHT: H-alpha detections of z~1 galaxies in the Hubble Deep Field North.
16083948
Multiple‐Object and Integral Field Near‐Infrared Spectroscopy Using Fibers
We describe a new system for multiple-object spectroscopy and integral field spectroscopy at near-infrared wavelengths using optical fibers. Both modes of the SMIRFS instrument have been tested at the UK Infrared Telescope with the CGS4 infrared spectrograph. The modular system includes a common optical system to image the fiber slit onto the cold slit inside the CGS4 cryostat. The multiobject mode consists of 14 interchangeable fused silica or zirconium fluoride fibers each with a field of 4''. The integral field mode consists of 72 fused silica fibers coupled with a lenslet array to give a contiguous field of 6'' × 4'' with sampling.We describe the performance of both modes. For the multiobject mode, the feasibility and desirability of using fluoride fibers to extend the wavelength range into the K band is discussed. For the integral field mode, the performance is compared with theoretical expectation with particular attention to the effect of focal ratio degradation in the fibers.These results demonstrate the feasibility of multiobject and integral field spectroscopy in the near-infrared using lenslet-coupled fiber systems. Although SMIRFS in an experimental system working with a spectrograph not designed for this purpose, the throughput and uniformity of response are good. SMIRFS points the way forward to systems with much larger numbers of elements.
14442375
The Anglo-Australian Observatory 2dF facility
The 2dF (Two-degree Field) facility at the prime focus of the Anglo-Australian Telescope provides multiple-object spectroscopy over a 2° field of view. Up to 400 target fibres can be independently positioned by a complex robot. Two spectrographs provide spectra with resolutions of between 500 and 2000, over wavelength ranges of 440 and 110 nm respectively. The 2dF facility began routine observations in 1997. 
 
 
 
2dF was designed primarily for galaxy redshift surveys and has a number of innovative features. The large corrector lens incorporates an atmospheric dispersion compensator, essential for wide wavelength coverage with small-diameter fibres. The instrument has two full sets of fibres on separate field plates, so that re-configuring can be done in parallel with observing. The robot positioner places one fibre every 6 s, to a precision of 0.3 arcsec (20 μm) over the full field. All components of 2dF, including the spectrographs, are mounted on a 5-m diameter telescope top end ring for ease of handling and to keep the optical fibres short in order to maximize UV throughput. 
 
 
 
There is a pipeline data reduction system which allows each data set to be fully analysed while the next field is being observed. 
 
 
 
2dF has achieved its initial astronomical goals. The redshift surveys obtain spectra at the rate of 2500 galaxies per night, yielding a total of about 200 000 objects in the first four years. Typically a B=19 galaxy gives a spectrum with a signal-to-noise ratio of better than 10 per pixel in less than an hour; redshifts are derived for about 95 per cent of all galaxies, with 99 per cent reliability or better. Total system throughput is about 5 per cent. The failure rate of the positioner and fibre system is about 1:10 000 moves or once every few nights, and recovery time is usually short. 
 
 
 
In this paper we provide the historical background to the 2dF facility, the design philosophy, a full technical description and a summary of the performance of the instrument. We also briefly review its scientific applications and possible future developments.