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2017-01-20
07:22
The $\Lambda$-parameter in 3-flavour QCD and $\alpha_s(m_Z)$ by the ALPHA collaboration / Bruno, M. (Brookhaven) ; Dalla Brida, M. (INFN, Milan Bicocca ; NIC, Zeuthen) ; Fritzsch, P. (CERN ; Madrid, IFT) ; Korzec, T. (Bergische U., Wuppertal (main)) ; Ramos, A. (CERN) ; Schaefer, S. (NIC, Zeuthen) ; Simma, H. (NIC, Zeuthen) ; Sint, S. (Trinity Coll., Dublin) ; Sommer, R. (NIC, Zeuthen ; Humboldt U., Berlin)
We present results by the ALPHA collaboration for the $\Lambda$-parameter in 3-flavour QCD and the strong coupling constant at the electroweak scale, $\alpha_s(m_Z)$, in terms of hadronic quantities computed on the CLS gauge configurations. The first part of this proceedings contribution contains a review of published material \cite{Brida:2016flw,DallaBrida:2016kgh} and yields the $\Lambda$-parameter in units of a low energy scale, $1/L_{\rm had}$. [...]
CERN-TH-2016-262; DESY-17-007; arXiv:1701.03075.- 2017-01-11 - 21 p. - Published in : PoS: LATTICE2016 (2016) , pp. 197 Fulltext: PDF;

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2017-01-20
07:22
Non-gaussianity of the critical 3d Ising model / Rychkov, Slava (CERN ; Ecole Normale Superieure ; UPMC, Paris (main)) ; Simmons-Duffin, David (Princeton, Inst. Advanced Study ; Caltech) ; Zan, Bernardo (ITPP, Lausanne ; CERN)
We discuss the 4pt function of the critical 3d Ising model, extracted from recent conformal bootstrap results. We focus on the non-gaussianity Q - the ratio of the 4pt function to its gaussian part given by three Wick contractions. [...]
arXiv:1612.02436; CERN-TH-2016-249.- 2017 - 10 p. - Published in : SciPost Phys. 2 (2017) 001 Preprint: PDF; SciPost Foundation Open Access article: PDF;

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2016-11-01
07:47
Massless Interacting Scalar Fields in de Sitter space / Nacir, Diana López (CERN) ; Mazzitelli, Francisco D (Balseiro Inst., San Carlos de Bariloche) ; Trombetta, Leonardo G (Balseiro Inst., San Carlos de Bariloche)
We present a method to compute the two-point functions for an $O(N)$ scalar field model in de Sitter spacetime, avoiding the well known infrared problems for massless fields. The method is based on an exact treatment of the Euclidean zero modes and a perturbative one of the nonzero modes, and involves a partial resummation of the leading secular terms. [...]
arXiv:1610.09943; CERN-TH-2016-151.- 2016 - 8 p. - Published in : EPJ Web Conf. 125 (2016) 05019 Preprint: PDF; External link: Preprint

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2016-10-28
07:41
D = 3 Unification of Curious Supergravities / Duff, M.J. (Imperial Coll., London ; Oxford U., Inst. Math.) ; Ferrara, S. (CERN ; INFN, Italy ; UCLA) ; Marrani, A. (Enrico Fermi Ctr., Rome ; INFN, Padua ; CERN ; Padua U.)
We consider the dimensional reduction to D = 3 of four maximal-rank supergravities which preserve minimal supersymmetry in D = 11, 7, 5 and 4. Such "curious" theories were investigated some time ago, and the four-dimensional one corresponds to an N = 1 supergravity with 7 chiral multiplets spanning the seven-disk manifold. [...]
arXiv:1610.08800; IMPERIAL-TP-2016-MJD-3; CERN-TH-2016-225; DFPD-2016-TH-18.- 2017 - 1+7 p. - Published in : J. High Energy Phys. 01 (2017) 023 Fulltext: PDF;

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2016-10-24
07:21
Exact $\nabla^4 R^4$ couplings and helicity supertraces / Bossard, Guillaume (Ecole Polytechnique, CPHT) ; Pioline, Boris (CERN ; Paris, LPTHE)
In type II string theory compactified on a $d$-dimensional torus $T^d$ down to $D=10-d$ dimensions, the $R^4$ and $\nabla^4 R^4$ four-graviton couplings are known exactly, for all values of the moduli, in terms of certain Eisenstein series of the U-duality group $E_{d}(\mathbb{Z})$. In the limit where one circle in the torus becomes large, these couplings are expected to reduce to their counterpart in dimension $D+1$, plus threshold effects and exponentially suppressed corrections corresponding to BPS black holes in dimension $D+1$ whose worldline winds around the circle. [...]
arXiv:1610.06693; CERN-TH-2016-224; CPHT-RR046.102016.- 2017 - 40 p. - Published in : J. High Energy Phys. 01 (2017) 050 Fulltext: PDF;

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2016-10-22
07:28
Science with the space-based interferometer LISA. IV: Probing inflation with gravitational waves / Bartolo, Nicola (Padua U. ; INFN, Padua ; Padua Observ.) ; Caprini, Chiara (APC, Paris) ; Domcke, Valerie (APC, Paris) ; Figueroa, Daniel G (CERN) ; Garcia-Bellido, Juan (Madrid, IFT) ; Guzzetti, Maria Chiara (Padua U. ; INFN, Padua) ; Liguori, Michele (Padua U. ; INFN, Padua ; Padua Observ.) ; Matarrese, Sabino (Padua U. ; INFN, Padua ; Padua Observ. ; GSSI, Aquila) ; Peloso, Marco (Minnesota U.) ; Petiteau, Antoine (APC, Paris) et al.
We investigate the potential for the LISA space-based interferometer to detect the stochastic gravitational wave background produced from different mechanisms during inflation. Focusing on well-motivated scenarios, we study the resulting contributions from particle production during inflation, inflationary spectator fields with varying speed of sound, effective field theories of inflation with specific patterns of symmetry breaking and models leading to the formation of primordial black holes. [...]
arXiv:1610.06481; ACFI-T16-19; UMN-TH-3608-16; CERN-TH-2016-222; KCL-PH-TH-2016-58; IFT--UAM-CSIC--16--104.- 2016 - 53 p. - Published in : J. Cosmol. Astropart. Phys. 12 (2016) 026 Fulltext: PDF; External link: Preprint

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2016-10-20
08:40
Towards an automated tool to evaluate the impact of the nuclear modification of the gluon density on quarkonium, D and B meson production in proton-nucleus collisions / Lansberg, Jean-Philippe (Orsay, IPN) ; Shao, Hua-Sheng (CERN)
We propose a simple and model-independent procedure to account for the impact of the nuclear modification of the gluon density as encoded in nuclear collinear PDF sets on two-to-two partonic hard processes in proton-nucleus collisions. This applies to a good approximation to quarkonium, D and B meson production, generically referred to H. [...]
arXiv:1610.05382; CERN-TH-2016-206.- 2017 - 18 p. - Published in : Eur. Phys. J. C 77 (2017) 1 Fulltext: PDF;

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2016-10-14
07:50
Seven-Disk Manifold, alpha-attractors and B-modes / Ferrara, Sergio (CERN ; Frascati ; UCLA) ; Kallosh, Renata (Stanford U., ITP ; Stanford U., Phys. Dept.)
Cosmological alpha-attractor models in \cN=1 supergravity are based on hyperbolic geometry of a Poincar\'e disk with the radius square {\cal R}^2=3\alpha. The predictions for the B-modes, r\approx 3\alpha {4\over N^2}, depend on moduli space geometry and are robust for a rather general class of potentials. [...]
arXiv:1610.04163; CERN-TH-2016-214.- 2016 - 7. - Published in : Phys. Rev. D 94 (2016) 126015 APS Open Access article: PDF; Fulltext: PDF; External link: Preprint

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2016-10-13
08:17
Six-dimensional Origin of $\mathcal{N}=4$ SYM with Duality Defects / Assel, Benjamin (CERN ; King's Coll. London, Dept. Math) ; Schäfer-Nameki, Sakura (Oxford U., Inst. Math. ; King's Coll. London, Dept. Math)
We study the topologically twisted compactification of the 6d $(2,0)$ M5-brane theory on an elliptically fibered K\"ahler three-fold preserving two supercharges. We show that upon reducing on the elliptic fiber, the 4d theory is $\mathcal{N}=4$ Super-Yang Mills, with varying complexified coupling $\tau$, in the presence of defects. [...]
arXiv:1610.03663; CERN-TH-2016-216.- 2016 - 62 p. - Published in : J. High Energy Phys. 12 (2016) 058 Fulltext: PDF; Springer Open Access article: PDF;

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2016-10-08
07:49
Time evolution of linearized gauge field fluctuations on a real-time lattice / Kurkela, Aleksi (CERN ; Stavanger U.) ; Lappi, Tuomas (Jyvaskyla U. ; Helsinki Inst. of Phys.) ; Peuron, Jarkko (Jyvaskyla U.)
Classical real-time lattice simulations play an important role in understanding non-equilibrium phenomena in gauge theories and are used in particular to model the prethermal evolution of heavy-ion collisions. Due to instabilities, small quantum fluctuations on top of the classical background may significantly affect the dynamics of the system. [...]
arXiv:1610.01355; CERN-TH-2016-208.- 2016 - 8 p. - Published in : Eur. Phys. J. C 76 (2016) 688 Fulltext: PDF; Springer Open Access article: PDF;

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