2,656 research outputs found
New Physics Effects in Higgs Decay to Tau Leptons
We study the possible effects of TeV scale new physics (NP) on the rate for
Higgs boson decays to charged leptons, focusing on the tau tau channel which
can be readily studied at the Large Hadron collider. Using an SU(3)_C X SU(2)_L
X U(1)_Y invariant effective theory valid below a NP scale Lambda, we determine
all effective operators up to dimension six that could generate appreciable
contributions to the decay rate and compute the dependence of the rate on the
corresponding operator coefficients. We bound the size of these operator
coefficients based on the scale of the tau mass, naturalness considerations,
and experimental constraints on the tau anomalous magnetic moment. These
considerations imply that contributions to the decay rate from a NP scale
Lambda ~ TeV could be comparable to the prediction based on the SM Yukawa
interaction. A reliable test of the Higgs mechanism for fermion mass generation
via the h-> tau tau channel is possible only after such NP effects are
understood and brought under theoretical control.Comment: 10 pages, 6 figures, V2: typos correcte
First Glimpses at Higgs' face
The 8 TeV LHC Higgs search data just released indicates the existence of a
scalar resonance with mass ~ 125 GeV. We examine the implications of the data
reported by ATLAS, CMS and the Tevatron collaborations on understanding the
properties of this scalar by performing joint fits on its couplings to other
Standard Model particles. We discuss and characterize to what degree this
resonance has the properties of the Standard Model (SM) Higgs, and consider
what implications can be extracted for New Physics in a (mostly)
model-independent fashion. We find that, if the Higgs couplings to fermions and
weak vector bosons are allowed to differ from their standard values, the SM is
~ 2 sigma from the best fit point to current data. Fitting to a possible
invisible decay branching ratio, we find BR_{inv} = 0.05\pm 0.32\ (95% C.L.) We
also discuss and develop some ways of using the data in order to bound or rule
out models which modify significantly the properties of this scalar resonance
and apply these techniques to the global current data set.Comment: 26 pages, 7 figures, v2 post ICHEP data updat
Jets in Effective Theory: Summing Phase Space Logs
We demonstrate how to resum phase space logarithms in the Sterman-Weinberg
(SW) dijet decay rate within the context of Soft Collinear Effective theory
(SCET). An operator basis corresponding to two and three jet events is defined
in SCET and renormalized. We obtain the RGE of the two and three jet operators
and run the operators from the scale to the phase space scale . This phase space scale, where is the
cone half angle of the jet, defines the angular region of the jet. At we determine the mixing of the three and two jet operators. We
combine these results with the running of the two jet shape function, which we
run down to an energy cut scale . This defines the resumed SW
dijet decay rate in the context of SCET. The approach outlined here
demonstrates how to establish a jet definition in the context of SCET. This
allows a program of systematically improving the theoretical precision of jet
phenomenology to be carried out.Comment: 25 pages, 4 figures, V2: Typos fixed, writing clarified, detail on
PSRG added. Matching onto jet definition changed to taking place at collinear
scal
Asymptotic safety of scalar field theories
We study 3d O(N)symmetric scalar field theories using Polchinski's renormalisation group. In the infinite N limit the model is solved exactly including at strong coupling. At short distances the theory is described by a line of asymptotically safe ultraviolet fixed points bounded by asymptotic freedom at weak, and the Bardeen-Moshe-Bander phenomenon at strong sextic coupling. The Wilson-Fisher fixed point arises as an isolated low-energy fixed point. Further results include the conformal window for asymptotic safety, convergence-limiting poles in the complex field plane, and the phase diagram with regions of first and second order phase transitions. We substantiate a duality between Polchinski's and Wetterich's versions of the functional renormalisation group, also showing that that eigenperturbations are identical at any fixed point. At a critical sextic coupling, the duality is worked out in detail to explain the spontaneous breaking of scale symmetry responsible for the generation of a light dilaton. Implications for asymptotic safety in other theories are indicated
Coordinating Expertise to Preserve and Increase Discoverability of Key University of Tennessee Agricultural Serials
This article describes a successful collaborative effort between a branch and the main campus library at the University of Tennessee (UT), Knoxville, to digitize agricultural serials. Experts in agricultural content, preservation, digitization, and metadata worked to preserve three agricultural print publications and make approximately 3,800 issues discoverable for patrons on campus and beyond. This discussion provides a background to Extension and the Experiment Station in Tennessee, outlines previous attempts made to digitize agricultural serials at UT Libraries, and details decisions made during the digitization process and metadata creation. These experiences offer a model for other libraries pursuing similar digitization projects
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Chronic opioid pretreatment potentiates the sensitization of fear learning by trauma.
Despite the large comorbidity between PTSD and opioid use disorders, as well as the common treatment of physical injuries resulting from trauma with opioids, the ability of opioid treatments to subsequently modify PTSD-related behavior has not been well studied. Using the stress-enhanced fear learning (SEFL) model for PTSD, we characterized the impact of chronic opioid regimens on the sensitization of fear learning seen following traumatic stress in mice. We demonstrate for the first time that chronic opioid pretreatment is able to robustly augment associative fear learning. Highlighting aversive learning as the cognitive process mediating this behavioral outcome, these changes were observed after a considerable period of drug cessation, generalized to learning about multiple aversive stimuli, were not due to changes in stimulus sensitivity or basal anxiety, and correlated with a marker of synaptic plasticity within the basolateral amygdala. Additionally, these changes were not observed when opioids were given after the traumatic event. Moreover, we found that neither reducing the frequency of opioid administration nor bidirectional manipulation of acute withdrawal impacted the subsequent enhancement in fear learning seen. Given the fundamental role of associative fear learning in the generation and progression of PTSD, these findings are of direct translational relevance to the comorbidity between opioid dependence and PTSD, and they are also pertinent to the use of opioids for treating pain resulting from traumas involving physical injuries
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