6,982 research outputs found
The Heat Kernel on
We explicitly evaluate the heat kernel for the Laplacian of arbitrary spin
tensor fields on the thermal quotient of (Euclidean) for
using the group theoretic techniques employed for in arXiv:0911.5085.
Our approach is general and can be used, in principle, for other quotients as
well as other symmetric spaces.Comment: Added references, added appendix on heat kernel in even dimensio
The Heat Kernel on AdS_3 and its Applications
We derive the heat kernel for arbitrary tensor fields on S^3 and (Euclidean)
AdS_3 using a group theoretic approach. We use these results to also obtain the
heat kernel on certain quotients of these spaces. In particular, we give a
simple, explicit expression for the one loop determinant for a field of
arbitrary spin s in thermal AdS_3. We apply this to the calculation of the one
loop partition function of N=1 supergravity on AdS_3. We find that the answer
factorizes into left- and right-moving super Virasoro characters built on the
SL(2, C) invariant vacuum, as argued by Maloney and Witten on general grounds.Comment: 46 pages, LaTeX, v2: Reference adde
First measurement of the cross section for top-quark pair production in proton–proton collisions at √s = 7 TeV
20 páginas, 3 figuras, 1 tabla.-- This article is published Open Access at sciencedirect.com. It
is distributed under the terms of the Creative Commons Attribution
License 3.0.-- CMS Collaboration: et al.The first measurement of the cross section for top-quark pair production in pp collisions at the
Large Hadron Collider at center-of-mass energy √s = 7 TeV has been performed using a data sample
corresponding to an integrated luminosity of 3.1 ± 0.3 pb−1 recorded by the CMS detector. This result
utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse
energy, and two or more jets. Backgrounds from Drell–Yan and non-W/Z boson production are estimated
from data. Eleven events are observed in the data with 2.1 ± 1.0 events expected from background. The
measured cross section is 194±72(stat.)±24(syst.)±21(lumi.) pb, consistent with next-to-leading order
predictions.Acknowledge support from: FMSR (Austria);
FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP
(Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China);
COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy
of Sciences and NICPB (Estonia); Academy of Finland, ME, and
HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF
(Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and
DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU
(Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI
(Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR
(Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE
(Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding
Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey);
STFC (United Kingdom); DOE and NSF (USA).Peer reviewe
Search for supersymmetry in pp collisions at 7 TeV in events with jets and missing transverse energy
Acknowledge support from:
FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ,
and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC
(China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus);
Academy of Sciences and NICPB (Estonia); Academy of Finland,
ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG,
and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary);
DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF
and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and
UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal);
JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST
and MAE (Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss
Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK
(Turkey); STFC (United Kingdom); DOE and NSF (USA).A search for supersymmetry with R-parity conservation in proton–proton collisions at a centre-of-mass
energy of 7 TeV is presented. The data correspond to an integrated luminosity of 35 pb−1 collected by
the CMS experiment at the LHC. The search is performed in events with jets and significant missing
transverse energy, characteristic of the decays of heavy, pair-produced squarks and gluinos. The primary
background, from standard model multijet production, is reduced by several orders of magnitude to a
negligible level by the application of a set of robust kinematic requirements. With this selection, the
data are consistent with the standard model backgrounds, namely t¯t, W + jet and Z + jet production,
which are estimated from data control samples. Limits are set on the parameters of the constrained
minimal supersymmetric extension of the standard model. These limits extend those set previously by
experiments at the Tevatron and LEP colliders.23 páginas, 5 figuras, 2 tablas.-- Open access:
This article is distributed under the terms of the Creative Commons Attribution
License 3.0.-- CMS Collaboration: et al.Peer reviewe
Measurement of Wγ and Zγ production in pp collisions at √s = 7 TeV
21 páginas, 7 figuras, 2 tablas.-- Open access:
This article is distributed under the terms of the Creative Commons Attribution
License 3.0.-- CMS collaboration: et al.A measurement of Wγ and Zγ production in proton–proton collisions at √s = 7 TeV is presented. Results
are based on a data sample recorded by the CMS experiment at the LHC, corresponding to an
integrated luminosity of 36 pb−1. The electron and muon decay channels of the W and Z are used. The
total cross sections are measured for photon transverse energy Eγ
T > 10 GeV and spatial separation from
charged leptons in the plane of pseudorapidity and azimuthal angle R( ,γ) > 0.7, and with an additional
dilepton invariant mass requirement of M > 50 GeV for the Zγ process. The following cross
section times branching fraction values are found: σ(pp→Wγ + X) × B(W→ ν) = 56.3 ± 5.0(stat.) ± 5.0(syst.)±2.3(lumi.) pb and σ(pp→Zγ + X)×B(Z→ ) = 9.4±1.0(stat.)±0.6(syst.)±0.4(lumi.) pb.
These measurements are in agreement with standard model predictions. The first limits on anomalous
WWγ , ZZγ , and Zγγ trilinear gauge couplings at √s =7 TeV are set.Acknowledge support from: FMSR (Austria);
FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP
(Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China);
COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy
of Sciences and NICPB (Estonia); Academy of Finland, ME, and
HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF
(Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and
DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU
(Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI
(Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR
(Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE
(Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding
Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey);
STFC (United Kingdom); DOE and NSF (USA).Peer reviewe
Search for a W boson decaying to a muon and a neutrino in pp collisions at √s = 7 TeV
20 páginas, 4 figuras, 3 tablas.-- Open access:
This article is distributed under the terms of the Creative Commons Attribution
License 3.0.-- CMS Collaboration: et al.A new heavy gauge boson, W', decaying to a muon and a neutrino, is searched for in pp collisions at a
centre-of-mass energy of 7 TeV. The data, collected with the CMS detector at the LHC, correspond to an
integrated luminosity of 36 pb−1. No significant excess of events above the standard model expectation
is found in the transverse mass distribution of the muon–neutrino system. Masses below 1.40 TeV are
excluded at the 95% confidence level for a sequential standard-model-like W'. The W' mass lower limit
increases to 1.58 TeV when the present analysis is combined with the CMS result for the electron channel.Acknowledge support from: FMSR (Austria);
FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP
(Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS
(Colombia); MSES (Croatia); RPF (Cyprus); Academy of
Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP
(Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF
(Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and
DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU
(Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI
(Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR
(Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE
(Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding
Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey);
STFC (United Kingdom); DOE and NSF (USA).Peer reviewe
Dynamical Symmetry Breaking in Spaces with Constant Negative Curvature
By using the Nambu-Jona-Lasinio model, we study dynamical symmetry breaking
in spaces with constant negative curvature. We show that the physical reason
for zero value of critical coupling value in these spaces is
connected with the effective reduction of dimension of spacetime in the infrared region, which takes place for any dimension . Since
the Laplace-Beltrami operator has a gap in spaces with constant negative
curvature, such an effective reduction for scalar fields is absent and there
are not problems with radiative corrections due to scalar fields. Therefore,
dynamical symmetry breaking with the effective reduction of the dimension of
spacetime for fermions in the infrared region is consistent with the
Mermin-Wagner-Coleman theorem, which forbids spontaneous symmetry breaking in
(1 + 1)-dimensional spacetime.Comment: minor text changes, added new reference
An electromagnetic shashlik calorimeter with longitudinal segmentation
A novel technique for longitudinal segmentation of shashlik calorimeters has
been tested in the CERN West Area beam facility. A 25 tower very fine samplings
e.m. calorimeter has been built with vacuum photodiodes inserted in the first 8
radiation lengths to sample the initial development of the shower. Results
concerning energy resolution, impact point reconstruction and electron/pion
separation are reported.Comment: 13 pages, 12 figure
Propagators and WKB-exactness in the plane wave limit of AdSxS
Green functions for the scalar, spinor and vector fields in a plane wave
geometry arising as a Penrose limit of are obtained. The
Schwinger-DeWitt technique directly gives the results in the plane wave
background, which turns out to be WKB-exact. Therefore the structural
similarity with flat space results is unveiled. In addition, based on the local
character of the Penrose limit, it is claimed that for getting the correct
propagators in the limit one can rely on the first terms of the direct geodesic
contribution in the Schwinger-DeWitt expansion of the original propagators .
This is explicitly shown for the Einstein Static Universe, which has the same
Penrose limit as with equal radii, and for a number of other
illustrative cases.Comment: 18 pages, late
Spectral Action for Robertson-Walker metrics
We use the Euler-Maclaurin formula and the Feynman-Kac formula to extend our
previous method of computation of the spectral action based on the Poisson
summation formula. We show how to compute directly the spectral action for the
general case of Robertson-Walker metrics. We check the terms of the expansion
up to a_6 against the known universal formulas of Gilkey and compute the
expansion up to a_{10} using our direct method
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