297 research outputs found
Supersymmetric Monojets at the Large Hadron Collider
Supersymmetric monojets may be produced at the Large Hadron Collider by the
process qg -> squark neutralino_1 -> q neutralino_1 neutralino_1, leading to a
jet recoiling against missing transverse momentum. We discuss the feasibility
and utility of the supersymmetric monojet signal. In particular, we examine the
possible precision with which one can ascertain the neutralino_1-squark-quark
coupling via the rate for monojet events. Such a coupling contains information
on the composition of the neutralino_1 and helps bound dark matter direct
detection cross-sections and the dark matter relic density of the neutralino_1.
It also provides a check of the supersymmetric relation between gauge couplings
and gaugino-quark-squark couplings.Comment: 46 pages, 10 figures. The appendix has been rewritten to correct an
error that appears in all previous versions of the appendix. This error has
no effect on the results in the main body of the pape
Changes in SARS-CoV-2 viral load and mortality during the initial wave of the pandemic in New York City
Funding: This work was partially supported by the National Center for Advancing Translational Sciences of the National Institutes of Health (UL1 TR0023484 to Julianne Imperato-McGinley) and the National Institute of Allergy and Infectious Diseases (UM1 AI069470 to M.E.S).Public health interventions such as social distancing and mask wearing decrease the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, but it is unclear whether they decrease the viral load of infected patients and whether changes in viral load impact mortality from coronavirus disease 2019 (COVID-19). We evaluated 6923 patients with COVID-19 at six New York City hospitals from March 15-May 14, 2020, corresponding with the implementation of public health interventions in March. We assessed changes in cycle threshold (CT) values from reverse transcription-polymerase chain reaction tests and in-hospital mortality and modeled the impact of viral load on mortality. Mean CT values increased between March and May, with the proportion of patients with high viral load decreasing from 47.7% to 7.8%. In-hospital mortality increased from 14.9% in March to 28.4% in early April, and then decreased to 8.7% by May. Patients with high viral loads had increased mortality compared to those with low viral loads (adjusted odds ratio 2.34). If viral load had not declined, an estimated 69 additional deaths would have occurred (5.8% higher mortality). SARS-CoV-2 viral load steadily declined among hospitalized patients in the setting of public health interventions, and this correlated with decreases in mortality.Peer reviewe
Sparticle Spectra and LHC Signatures for Large Volume String Compactifications
We study the supersymmetric particle spectra and LHC collider observables for
the large-volume string models with a fundamental scale of 10^{11} GeV that
arise in moduli-fixed string compactifications with branes and fluxes. The
presence of magnetic fluxes on the brane world volume, required for chirality,
perturb the soft terms away from those previously computed in the dilute-flux
limit. We use the difference in high-scale gauge couplings to estimate the
magnitude of this perturbation and study the potential effects of the magnetic
fluxes by generating many random spectra with the soft terms perturbed around
the dilute flux limit. Even with a 40% variation in the high-scale soft terms
the low-energy spectra take a clear and predictive form. The resulting spectra
are broadly similar to those arising on the SPS1a slope, but more degenerate.
In their minimal version the models predict the ratios of gaugino masses to be
M_1 : M_2 : M_3=(1.5 - 2) : 2 : 6, different to both mSUGRA and mirage
mediation. Among the scalars, the squarks tend to be lighter and the sleptons
heavier than for comparable mSUGRA models. We generate 10 fb^{-1} of sample LHC
data for the random spectra in order to study the range of collider
phenomenology that can occur. We perform a detailed mass reconstruction on one
example large-volume string model spectrum. 100 fb^{-1} of integrated
luminosity is sufficient to discriminate the model from mSUGRA and aspects of
the sparticle spectrum can be accurately reconstructed.Comment: 42 pages, 21 figures. Added references and discussion for section 3.
Slight changes in the tex
Quantum Computing Without Wavefunctions: Time-Dependent Density Functional Theory for Universal Quantum Computation
We prove that the theorems of TDDFT can be extended to a class of qubit Hamiltonians that are universal for quantum computation. The theorems of TDDFT applied to universal Hamiltonians imply that single-qubit expectation values can be used as the basic variables in quantum computation and information theory, rather than wavefunctions. From a practical standpoint this opens the possibility of approximating observables of interest in quantum computations directly in terms of single-qubit quantities (i.e. as density functionals). Additionally, we also demonstrate that TDDFT provides an exact prescription for simulating universal Hamiltonians with other universal Hamiltonians that have different, and possibly easier-to-realize two-qubit interactions. This establishes the foundations of TDDFT for quantum computation and opens the possibility of developing density functionals for use in quantum algorithms
Recommended from our members
Search for intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network
Gravitational-wave astronomy has been firmly established with the detection of gravitational waves from the merger of ten stellar-mass binary black holes and a neutron star binary. This paper reports on the all-sky search for gravitational waves from intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network. The search uses three independent algorithms: two based on matched filtering of the data with waveform templates of gravitational-wave signals from compact binaries, and a third, model-independent algorithm that employs no signal model for the incoming signal. No intermediate mass black hole binary event is detected in this search. Consequently, we place upper limits on the merger rate density for a family of intermediate mass black hole binaries. In particular, we choose sources with total masses M=m1+m2Ï”[120,800] M and mass ratios q=m2/m1Ï”[0.1,1.0]. For the first time, this calculation is done using numerical relativity waveforms (which include higher modes) as models of the real emitted signal. We place a most stringent upper limit of 0.20 Gpc-3 yr-1 (in comoving units at the 90% confidence level) for equal-mass binaries with individual masses m1,2=100 M and dimensionless spins Ï1,2=0.8 aligned with the orbital angular momentum of the binary. This improves by a factor of âŒ5 that reported after Advanced LIGO's first observing run
Search for Chargino-Neutralino Associated Production at the Fermilab Tevatron Collider
We have searched in collisions at = 1.8 TeV for events
with three charged leptons and missing transverse energy. In the Minimal
Supersymmetric Standard Model, we expect trilepton events from
chargino-neutralino (\chione \chitwo) pair production, with subsequent decay
into leptons. We observe no candidate , ,
or events in 106 pb integrated
luminosity. We present limits on the sum of the branching ratios times cross
section for the four channels: \sigma_{\chione\chitwo}\cdot
BR(\chione\chitwo\to 3\ell+X) 81.5 \mgev\sp and
M_\chitwo > 82.2 \mgev\sp for , ~\mgev\sp and
M_\squark= M_\gluino.Comment: 9 pages and 3 figure
US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report
This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in
Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference
Renormalisation group improved leptogenesis in family symmetry models
We study renormalisation group (RG) corrections relevant for leptogenesis in
the case of family symmetry models such as the Altarelli-Feruglio A4 model of
tri-bimaximal lepton mixing or its extension to tri-maximal mixing. Such
corrections are particularly relevant since in large classes of family symmetry
models, to leading order, the CP violating parameters of leptogenesis would be
identically zero at the family symmetry breaking scale, due to the form
dominance property. We find that RG corrections violate form dominance and
enable such models to yield viable leptogenesis at the scale of right-handed
neutrino masses. More generally, the results of this paper show that RG
corrections to leptogenesis cannot be ignored for any family symmetry model
involving sizeable neutrino and tau Yukawa couplings.Comment: 24 pages, 6 figures and 1 tabl
Archive of Darkness:William Kentridge's Black Box/Chambre Noire
Situating itself in histories of cinema and installation art, William Kentridge's Black Box/Chambre Noire (2005) raises questions about screens, exhibition space, site-specificity and spectatorship. Through his timely intervention in a debate on Germanyâs colonial past, Kentridgeâs postcolonial art has contributed to the recognition and remembrance of a forgotten, colonial genocide. This article argues that, by transposing his signature technique of drawings for projection onto a new set of media, Kentridge explores how and what we can know through cinematic projection in the white cube. In particular, his metaphor of the illuminated shadow enables him to animate archival fragments as shadows and silhouettes. By creating a multi-directional archive, Black Box enables an affective engagement with the spectres of colonialism and provides a forum for the calibration of moral questions around reparation, reconciliation and forgiveness
Search for Scalar Top and Scalar Bottom Quarks in collisions at TeV
We have searched for direct pair production of scalar top and scalar bottom
quarks in 88 pb of collisions at TeV with the
CDF detector. We looked for events with a pair of heavy flavor jets and missing
energy, consistent with scalar top quark decays to a charm quark and a
neutralino, or scalar bottom quark decays to a bottom quark and a neutralino.
The numbers of events that pass our selection for each process show no
deviation from Standard Model expectations. We compare our results to
next-to-leading order calculations for the scalar quark production cross
sections to exclude regions in scalar quark-neutralino parameter space.Comment: 10 pages, 3 figures. Submitted to Physical Review Letter
- âŠ