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Exotic matter on singular divisors in Ftheory
http://cds.cern.ch/record/2271783
We analyze exotic matter representations that arise on singular sevenbrane configurations in Ftheory. We develop a general framework for analyzing such representations, and work out explicit descriptions for models with matter in the 2index and 3index symmetric representations of SU($N$) and SU(2) respectively, associated with double and triple point singularities in the sevenbrane locus. These matter representations are associated with Weierstrass models whose discriminants vanish to high order thanks to nontrivial cancellations possible only in the presence of a nonUFD algebraic structure. This structure can be described using the normalization of the ring of intrinsic local functions on a singular divisor. We consider the connection between geometric constraints on singular curves and corresponding constraints on the lowenergy spectrum of 6D theories, identifying some new examples of apparent "swampland" theories that cannot be realized in Ftheory but have no apparent lowenergy inconsistency.
Klevers, Denis
Morrison, David R.
Raghuram, Nikhil
Taylor, Washington
Tue, 27 Jun 2017 06:02:15 GMT
20170625
CERNTH2016252
http://cds.cern.ch/record/2271783
2016
252

$B$ decay anomalies from nonabelian local horizontal symmetry
http://cds.cern.ch/record/2271782
Recent anomalies in $B\to K^{(*)}\ell\ell$ meson decays are consistent with exchange of a heavy $Z'$ vector boson. Here we try to connect such new physics to understanding the origin of flavor, by gauging generation number. Phenomenological and theoretical considerations suggest that the smallest viable flavor symmetry (not including any extra U(1) factors) is chiral ${\rm SU(3)}_L\times{\rm SU(3)}_R$, which acts only on generation indices and does not distinguish between quarks and leptons. Spontaneous breaking of the symmetry gives rise to the standard model Yukawa matrices, and masses for the 16 $Z'$like gauge bosons, one of which is presumed to be light enough to explain the $B\to K^{(*)}\ell\ell$ anomalies. We perform a bottomup study of this framework, showing that it is highly constrained by LHC dilepton searches, meson mixing, $Z$ decays and CKM unitarity. Similar anomalies are predicted for semileptonic decays of $B$ to lighter mesons, with excesses in the $ee,\tau\tau$ channels and deficits in $\mu\mu$, but no deviation in $\nu\nu$. The lightest $Z'$ mass is $\lesssim 6\,$TeV if the gauge coupling is $\lesssim 1$.
Cline, James M.
Martin Camalich, Jorge
Tue, 27 Jun 2017 06:02:14 GMT
20170626
CERNTH2017136
http://cds.cern.ch/record/2271782
2017
136

Status of the Charged Higgs Boson in Two Higgs Doublet Models
http://cds.cern.ch/record/2271322
The existence of charged Higgs boson(s) is inevitable in models with two (or more) Higgs doublets. Hence, their discovery would constitute unambiguous evidence for new physics beyond the Standard Model (SM). Taking into account all relevant results from direct charged and neutral Higgs boson searches at LEP and the LHC, as well as the most recent constraints from flavour physics, we present a detailed analysis of the current phenomenological status of the charged Higgs sector in a variety of wellmotivated Two Higgs Doublet Models (2HDMs). We find that charged Higgs bosons as light as 75 GeV can still be compatible with the combined data, although this implies severely suppressed charged Higgs couplings to all fermions. In more popular models, e.g. the 2HDM of Type II, we find that flavour physics observables impose a combined lower limit on the charged Higgs mass of M_H+ > 600 GeV  independent of tan(beta)  which increases to M_H+ > 650 GeV for tan(beta) < 1. We furthermore find that in certain scenarios, the signature of a charged Higgs boson decaying into a lighter neutral Higgs boson and a W boson provides a promising experimental avenue that would greatly complement the existing LHC search programme for charged Higgs boson(s).
Arbey, A.
Mahmoudi, F.
Stal, O.
Stefaniak, T.
Sat, 24 Jun 2017 07:59:38 GMT
20170622
CERNTH2017137
http://cds.cern.ch/record/2271322
2017
137

A determination of the fragmentation functions of pions, kaons, and protons with faithful uncertainties
http://cds.cern.ch/record/2271320
We present NNFF1.0, a new determination of the fragmentation functions (FFs) of charged pions, charged kaons, and protons/antiprotons from an analysis of singleinclusive hadron production data in electronpositron annihilation. This determination, performed at leading, nexttoleading, and nexttonexttoleading order in perturbative QCD, is based on the NNPDF methodology, a fitting framework designed to provide a statistically sound representation of FF uncertainties and to minimise any procedural bias. We discuss novel aspects of the methodology used in this analysis, namely an optimised parametrisation of FFs and a more efficient $\chi^2$ minimisation strategy, and validate the FF fitting procedure by means of closure tests. We then present the NNFF1.0 sets, and discuss their fit quality, their perturbative convergence, and their stability upon variations of the kinematic cuts and the fitted dataset. We find that the systematic inclusion of higherorder QCD corrections significantly improves the description of the data, especially in the small$z$ region. We compare the NNFF1.0 sets to other recent sets of FFs, finding in general a reasonable agreement, but also important differences. Together with existing sets of unpolarised and polarised parton distribution functions (PDFs), FFs and PDFs are now available from a common fitting framework for the first time.
Bertone, Valerio
Carrazza, Stefano
Hartland, Nathan P.
Nocera, Emanuele R.
Rojo, Juan
Sat, 24 Jun 2017 07:59:21 GMT
20170621
CERNTH2017122
http://cds.cern.ch/record/2271320
2017
122

HighPrecision Calculations in Strongly Coupled Quantum Field Theory with NexttoLeadingOrder Renormalized Hamiltonian Truncation
http://cds.cern.ch/record/2271318
Hamiltonian Truncation (a.k.a. Truncated Spectrum Approach) is an efficient numerical technique to solve strongly coupled QFTs in d=2 spacetime dimensions. Further theoretical developments are needed to increase its accuracy and the range of applicability. With this goal in mind, here we present a new variant of Hamiltonian Truncation which exhibits smaller dependence on the UV cutoff than other existing implementations, and yields more accurate spectra. The key idea for achieving this consists in integrating out exactly a certain class of high energy states, which corresponds to performing renormalization at the cubic order in the interaction strength. We test the new method on the strongly coupled twodimensional quartic scalar theory. Our work will also be useful for the future goal of extending Hamiltonian Truncation to higher dimensions d >= 3.
EliasMiro, Joan
Rychkov, Slava
Vitale, Lorenzo G.
Sat, 24 Jun 2017 07:59:16 GMT
20170619
CERNTH2017132
http://cds.cern.ch/record/2271318
2017
132

Phase structure of complete asymptotically free SU($N_c$) theories with quarks and scalar quarks
http://cds.cern.ch/record/2271317
We determine the phase diagram of complete asymptotically free SU($N_c$) gauge theories featuring $N_s$ complex scalars and $N_f$ Dirac quarks transforming according to the fundamental representation of the gauge group. The analysis is performed at the maximum known order in perturbation theory. We unveil a very rich dynamics and associated phase structure. Intriguingly we discover that the complete asymptotically free conditions guarantee that the infrared dynamics displays long distance conformality, and in a regime when perturbation theory is applicable. We conclude our analysis by determining the quantum corrected potential of the theory and summarising the possible patterns of radiative symmetry breaking. These theories are of potential phenomenological interest as either elementary or composite ultraviolet finite extensions of the Standard Model.
Hansen, Frederik F.
Janowski, Tadeusz
Langaeble, Kasper
Mann, Robert B.
Sannino, Francesco
Steele, Tom G.
Wang, ZhiWei
Sat, 24 Jun 2017 07:59:07 GMT
20170620
CP3ORIGINS2017022DNRF90
http://cds.cern.ch/record/2271317
022
DNRF90

Radiative energy loss of neighboring subjets
http://cds.cern.ch/record/2270580
We compute the inmedium energy loss probability distribution of two neighboring subjets at leading order, in the large$N_c$ approximation. Our result exhibits a gradual onset of color decoherence of the system and accounts for two expected limiting cases. When the angular separation is smaller than the characteristic angle for mediuminduced radiation, the twopronged substructure lose energy coherently as a single color charge, namely that of the parent parton. At large angular separation the two subjets lose energy independently. Our result is a first step towards quantifying effects of energy loss as a result of the fluctuation of the multiparton jet substructure and therefore goes beyond the standard approach to jet quenching based on single parton energy loss. We briefly discuss applications to jet observables in heavyion collisions.
MehtarTani, Yacine
Tywoniuk, Konrad
Tue, 20 Jun 2017 05:43:25 GMT
20170619
arXiv:1706.06047
http://cds.cern.ch/record/2270580
['arXiv:1706.06047']
arXiv:1706.06047

The strong coupling from a nonperturbative determination of the $\Lambda$ parameter in threeflavor QCD
http://cds.cern.ch/record/2269091
We present a lattice determination of the $\Lambda$ parameter in threeflavor QCD and the strong coupling at the Z pole mass. Computing the nonperturbative running of the coupling in the range from $0.2\,$GeV to $70\,$GeV, and using experimental input values for the masses and decay constants of the pion and the kaon, we obtain $\Lambda_{\overline{\rm MS}}^{(3)}=341(12)\,$MeV. The nonperturbative running up to very high energies guarantees that systematic effects associated with perturbation theory are well under control. Using the fourloop prediction for $\Lambda_{\overline{\rm MS}}^{(5)}/\Lambda_{\overline{\rm MS}}^{(3)}$ yields $\alpha^{(5)}_{\overline{\rm MS}}(m_{\rm Z}) = 0.11852(84)$.
Bruno, M.
Dalla Brida, M.
Fritzsch, P.
Korzec, T.
Ramos, A.
Schaefer, S.
Simma, H.
Sint, S.
Sommer, R.
Thu, 15 Jun 2017 06:10:31 GMT
20170612
CERNTH2017129
http://cds.cern.ch/record/2269091
2017
129

Uncovering new strong dynamics via topological interactions at the 100 TeV collider
http://cds.cern.ch/record/2269090
In models of composite Higgs dynamics new composite pseudoscalars can interact with the Higgs and electroweak gauge bosons via anomalous interactions, stemming from the topological sector of the underlying theory. We show that a future 100 TeV protonproton collider (FCCpp) will be able to test this important sector and thus shed light on the strong dynamics which generates the Higgs and other composite states. To elucidate our results we focus on the topological interactions of a minimal composite Higgs model with a fermionic ultraviolet completion, based on the coset $\text{SU}(4)/\text{Sp}(4)$. We suggest the strategy to test these interactions at the FCCpp and analyse the expected reach.
Molinaro, Emiliano
Sannino, Francesco
Thomsen, Anders Eller
Vignaroli, Natascia
Thu, 15 Jun 2017 06:10:26 GMT
20170613
CP3ORIGINS2017021DNRF90
http://cds.cern.ch/record/2269090
021
DNRF90

A Novel Foamy Origin for Singlet Fermion Masses
http://cds.cern.ch/record/2269089
We show how masses for singlet fermions can be generated by interactions with a Dparticle model of spacetime foam inspired by brane theory. It has been shown previously by one of the authors (N.E.M.) such interactions may generate generate dynamically small masses for charged fermions via the recoils of Dparticle defects interacting with photons. In this work we consider the direct interactions of Dparticle with uncharged singlet fermions such as righthanded neutrinos. Quantum fluctuations of the lattice of Dparticles have massless vector (spinone) excitations that are analogues of phonons. These mediate forces between the singlet fermions, generating large dynamical masses that may be communicated to light neutrinos via the seesaw mechanism.
Ellis, John
Mavromatos, Nick E.
Nanopoulos, Dimitri V.
Thu, 15 Jun 2017 06:10:24 GMT
20170612
CERNTH2017123
http://cds.cern.ch/record/2269089
2017
123

Machine Learning of CalabiYau Volumes
http://cds.cern.ch/record/2268926
We employ machine learning techniques to investigate the volume minimum of SasakiEinstein base manifolds of noncompact toric CalabiYau 3folds. We find that the minimum volume can be approximated via a second order multiple linear regression on standard topological quantities obtained from the corresponding toric diagram. The approximation improves further after invoking a convolutional neural network with the full toric diagram of the CalabiYau 3folds as the input. We are thereby able to circumvent any minimization procedure that was previously necessary and find an explicit mapping between the minimum volume and the topological quantities of the toric diagram. Under the AdS/CFT correspondence, the minimum volumes of SasakiEinstein manifolds correspond to central charges of a class of 4d N=1 superconformal field theories. We therefore find empirical evidence for a function that gives values of central charges without the usual extremization procedure.
Krefl, Daniel
Seong, RakKyeong
Wed, 14 Jun 2017 06:09:39 GMT
20170611
CERNTH2017128
http://cds.cern.ch/record/2268926
2017
128

Singleelectron and singlephoton sensitivity with a silicon Skipper CCD
http://cds.cern.ch/record/2268243
We have developed a nondestructive readout system that uses a floatinggate amplifier on a thick, fully depleted charge coupled device (CCD) to achieve ultralow readout noise of 0.068 e rms/pix. This is the first time that discrete subelectron readout noise has been achieved reproducibly over millions of pixels on a stable, largearea detector. This allows the precise counting of the number of electrons in each pixel, ranging from pixels with 0 electrons to more than 1500 electrons. The resulting CCD detector is thus an ultrasensitive calorimeter. It is also capable of counting single photons in the optical and nearinfrared regime. Implementing this innovative nondestructive readout system has a negligible impact on CCD design and fabrication, and there are nearly immediate scientific applications. As a particle detector, this CCD will have unprecedented sensitivity to lowmass dark matter particles and coherent neutrinonucleus scattering, while astronomical applications include future direct imaging and spectroscopy of exoplanets.
Tiffenberg, Javier
SofoHaro, Miguel
DrlicaWagner, Alex
Essig, Rouven
Guardincerri, Yann
Holland, Steve
Volansky, Tomer
Yu, TienTien
Fri, 09 Jun 2017 05:21:37 GMT
20170531
arXiv:1706.00028
http://cds.cern.ch/record/2268243
['arXiv:1706.00028']
arXiv:1706.00028

What is the scale of new physics behind the $B$flavour anomalies?
http://cds.cern.ch/record/2267921
Motivated by the recent hints of lepton flavour nonuniversality in $B$meson semileptonic decays, we study the constraints of perturbative unitarity on the new physics interpretation of the anomalies in $b \to c \ell \bar \nu$ and $b \to s \ell \bar \ell$ transitions. Within an effective field theory approach we find that $2 \to 2$ fermion scattering amplitudes saturate the unitarity bound below 9 TeV and 80 TeV, respectively for $b \to c \ell \bar \nu$ and $b \to s \ell \bar \ell$ transitions. Stronger bounds, up to few TeV, are obtained when the leading effective operators are oriented in the direction of the third generation, as suggested by flavour models. We finally address unitarity constraints on simplified models explaining the anomalies and show that the new physics interpretation is ruled out in a class of perturbative realizations.
Di Luzio, Luca
Nardecchia, Marco
Wed, 07 Jun 2017 05:50:45 GMT
20170606
IPPP1750
http://cds.cern.ch/record/2267921
17
50

The Space of Vacua of 3d $\mathcal{N}=3$ Abelian Theories
http://cds.cern.ch/record/2267557
We use brane techniques to study the space of vacua of abelian 3d $\mathcal{N}=3$ gauge theories. The coordinates on these spaces are the vevs of chiral monopole and meson operators, which are realized in the type IIB brane configuration of the theory by adding semiinfinite $(1,k)$ strings or F1 strings. The study of various brane setups allows us to determine a basis of chiral operators and chiral ring relations relevant to each branch of vacua, leading to the algebraic description of these branches. The method is mostly graphical and does not require actual computations. We apply it and provide explicit results in various examples. For linear quivers we find that the space of vacua has in general a collection of Coulomblike branches, a Higgs branch and mixed branches. For circular quivers we find an extra branch, the geometric branch, parametrized by monopoles with equal magnetic charges in all $U(1)$ nodes and meson operators. We explain how to include FI and mass deformations. We also study $\mathcal{N}=3$ theories realized with $(p,q)$ 5branes.
Assel, Benjamin
Tue, 06 Jun 2017 05:25:20 GMT
20170602
CERNTH2017120
http://cds.cern.ch/record/2267557
2017
120

(Higgs) vacuum decay during inflation
http://cds.cern.ch/record/2267556
We develop the formalism for computing gravitational corrections to vacuum decay from de Sitter space as a subPlanckian perturbative expansion. Nonminimal coupling to gravity can be encoded in an effective potential. The Coleman bounce continuously deforms into the HawkingMoss bounce, until they coincide for a critical value of the Hubble constant. As an application, we reconsider the decay of the electroweak Higgs vacuum during inflation. Our vacuum decay computation reproduces and improves bounds on the maximal inflationary Hubble scale previously computed through statistical techniques.
Joti, Aris
Katsis, Aris
Loupas, Dimitris
Salvio, Alberto
Strumia, Alessandro
Tetradis, Nikolaos
Urbano, Alfredo
Tue, 06 Jun 2017 05:25:19 GMT
20170602
CERNTH2017121
http://cds.cern.ch/record/2267556
2017
121

Parton distributions from highprecision collider data
http://cds.cern.ch/record/2267455
We present a new set of parton distributions, NNPDF3.1, which updates NNPDF3.0, the first global set of PDFs determined using a methodology validated by a closure test. The update is motivated by recent progress in methodology and available data, and involves both. On the methodological side, we now parametrize and determine the charm PDF alongside the light quarks and gluon ones, thereby increasing from seven to eight the number of independent PDFs. On the data side, we now include the D0 electron and muon W asymmetries from the final Tevatron dataset, the complete LHCb measurements of W and Z production in the forward region at 7 and 8 TeV, and new ATLAS and CMS measurements of inclusive jet and electroweak boson production. We also include for the first time topquark pair differential distributions and the transverse momentum of the Z bosons from ATLAS and CMS. We investigate the impact of parametrizing charm and provide evidence that the accuracy and stability of the PDFs are thereby improved. We study the impact of the new data by producing a variety of determinations based on reduced datasets. We find that both improvements have a significant impact on the PDFs, with some substantial reductions in uncertainties, but with the new PDFs generally in agreement with the previous set at the one sigma level. The most significant changes are seen in the lightquark flavor separation, and in increased precision in the determination of the gluon. We explore the implications of NNPDF3.1 for LHC phenomenology at Run II, compare with recent LHC measurements at 13 TeV, provide updated predictions for Higgs production crosssections and discuss the strangeness and charm content of the proton in light of our improved dataset and methodology. The NNPDF3.1 PDFs are delivered for the first time both as Hessian sets, and as optimized Monte Carlo sets with a compressed number of replicas.
Ball, Richard D.
Bertone, Valerio
Carrazza, Stefano
Del Debbio, Luigi
Forte, Stefano
GrothMerrild, Patrick
Guffanti, Alberto
Hartland, Nathan P.
Kassabov, Zahari
Latorre, JosÃ© I.
Nocera, Emanuele R.
Rojo, Juan
Rottoli, Luca
Slade, Emma
Ubiali, Maria
Mon, 05 Jun 2017 05:15:55 GMT
20170601
CAVENDISHHEP1706
http://cds.cern.ch/record/2267455
17
06

Flavoured $BL$ Local Symmetry and Anomalous Rare $B$ Decays
http://cds.cern.ch/record/2267170
We consider a flavoured $BL$ gauge symmetry under which only the third generation fermions are charged. Such a symmetry can survive at low energies ($\sim\,$TeV) while still allowing for two superheavy righthanded neutrinos, consistent with neutrino masses via seesaw and leptogenesis. We describe a mechanism for generating Yukawa couplings in this model and also discuss the lowenergy phenomenology. Interestingly, the new gauge boson could explain the recent hints of lepton universality violation at LHCb, with a gauge coupling that remains perturbative up to the Planck scale. Finally, we discuss more general $U(1)$ symmetries and show that there exist only two classes of $U(1)$ that are both consistent with leptogenesis and remain phenomenologically viable at lowenergies.
Alonso, Rodrigo
Cox, Peter
Han, Chengcheng
Yanagida, Tsutomu T.
Fri, 02 Jun 2017 05:30:53 GMT
20170510
arXiv:1705.03858
http://cds.cern.ch/record/2267170
['arXiv:1705.03858']
arXiv:1705.03858

Direct comparison of global fits to the B >$ K^* $$\mu^+\mu^$ data assuming hadronic corrections or new physics
http://cds.cern.ch/record/2266909
The LHCb measurements on the B >$ K^*$$\mu^+ \mu^$ angular observables have shown slight deviations from their Standard Model predictions. The significance of the deviations in the B > $K^*$$\mu^+ \mu^$ decay depends on the assumptions on the size of the nonfactorisable power corrections. At present, there are no theoretical predictions on the size of these power corrections in order to identify whether the reason behind these anomalies is due to unknown hadronic corrections or New Physics effects. We have performed a statistical comparison of fitting the data to each of the possible explanations.
Neshatpour, S.
Chobanova, V.G.
Hurth, T.
Mahmoudi, F.
Martinez Santos, D.
Thu, 01 Jun 2017 05:33:06 GMT
20170530
CERNTH2017118
http://cds.cern.ch/record/2266909
2017
118

The analytic structure and the transcendental weight of the BFKL ladder at NLL accuracy
http://cds.cern.ch/record/2266434
We study some analytic properties of the BFKL ladder at nexttoleading logarithmic accuracy (NLLA). After generalising a procedure by Chirilli and Kovchegov to construct consistent NLO eigenfunctions for any value of $n$, we show that the BFKL ladder can be evaluated order by order in the coupling in terms of certain generalised singlevalued multiple polylogarithms recently introduced by Schnetz. We develop techniques to evaluate the BFKL ladder at any loop order, and we present explicit results up to five loops. Using the freedom in defining the matter content of the NLO BFKL eigenvalue, we obtain conditions for the BFKL ladder in momentum space at NLLA to have maximal transcendental weight. We observe that, unlike in moment space, the result in momentum space in N=4 SYM is not identical to the maximal weight part of QCD, and moreover that there is no gauge theory with this property. We classify the theories for which the BFKL ladder at NLLA has maximal weight in terms of their field content, and we find that these theories are highly constrained: there are precisely four classes of theories with this property involving only fundamental and adjoint matter, all of which have a vanishing oneloop beta function and a matter content that fits into supersymmetric multiplets. Our findings indicate that theories which have maximal weight are highly constrained and point to the possibility that there is a connection between maximal transcendentality weight and superconformal symmetry.
Del Duca, Vittorio
Duhr, Claude
Marzucca, Robin
Verbeek, Bram
Tue, 30 May 2017 07:03:05 GMT
20170529
CP31714
http://cds.cern.ch/record/2266434
17
14

Comment on "Disassembling the Clockwork Mechanism"
http://cds.cern.ch/record/2266433
We respond to the criticism raised in the paper arXiv:1704.07831.
Giudice, Gian F.
McCullough, Matthew
Tue, 30 May 2017 07:03:03 GMT
20170529
CERNTH2017108
http://cds.cern.ch/record/2266433
2017
108

Lattice implementation of Abelian gauge theories with ChernSimons number and an axion field
http://cds.cern.ch/record/2266116
Real time evolution of classical gauge fields is relevant for a number of applications in particle physics and cosmology, ranging from the early Universe to dynamics of quarkgluon plasma. We present a lattice formulation of the interaction between a $shift$symmetric field and some $U(1)$ gauge sector, $a(x)\tilde{F}_{\mu\nu}F^{\mu\nu}$, reproducing the continuum limit to order $\mathcal{O}(dx_\mu^2)$ and obeying the following properties: (i) the system is gauge invariant and (ii) shift symmetry is exact on the lattice. For this end we construct a definition of the {\it topological number density} $Q = \tilde{F}_{\mu\nu}F^{\mu\nu}$ that admits a lattice total derivative representation $Q = \Delta_\mu^+ K^\mu$, reproducing to order $\mathcal{O}(dx_\mu^2)$ the continuum expression $Q = \partial_\mu K^\mu \propto \vec E \cdot \vec B$. If we consider a homogeneous field $a(x) = a(t)$, the system can be mapped into an Abelian gauge theory with Hamiltonian containing a ChernSimons term for the gauge fields. This allow us to study in an accompanying paper the real time dynamics of fermion number nonconservation (or chirality breaking) in Abelian gauge theories at finite temperature. When $a(x) = a(\vec x,t)$ is inhomogeneous, the set of lattice equations of motion do not admit however a simple explicit local solution (while preserving an $\mathcal{O}(dx_\mu^2)$ accuracy). We discuss an iterative scheme allowing to overcome this difficulty.
Figueroa, Daniel G.
Shaposhnikov, Mikhail
Mon, 29 May 2017 05:16:10 GMT
20170526
CERNTH2017116
http://cds.cern.ch/record/2266116
2017
116

An Etude on Global Vacuum Energy Sequester
http://cds.cern.ch/record/2266050
Recently two of the authors proposed a mechanism of vacuum energy sequester as a means of protecting the observable cosmological constant from quantum radiative corrections. The original proposal was based on using global Lagrange multipliers, but later a local formulation was provided. Subsequently other interesting claims of a different nonlocal approach to the cosmological constant problem were made, based again on global Lagrange multipliers. We examine some of these proposals and find their mutual relationship. We explain that the proposals which do not treat the cosmological constant counterterm as a dynamical variable require fine tunings to have acceptable solutions. Furthermore, the counterterm often needs to be retuned at every order in the loop expansion to cancel the radiative corrections to the cosmological constant, just like in standard GR. These observations are an important reminder of just how the proposal of vacuum energy sequester avoids such problems.
D'Amico, Guido
Kaloper, Nemanja
Padilla, Antonio
Stefanyszyn, David
Westphal, Alexander
Zahariade, George
Sat, 27 May 2017 05:20:50 GMT
20170524
CERNTH2017115
http://cds.cern.ch/record/2266050
2017
115

Momentumspace resummation for transverse observables and the Higgs $p_\perp$ at N$^3$LL+NNLO
http://cds.cern.ch/record/2266049
We present an approach to the momentumspace resummation of global, recursive infrared and collinear safe observables featuring kinematic zeros away from the Sudakov limit. In the hadroproduction of a generic colour singlet, we consider the family of inclusive observables which do not depend on the rapidity of the radiation, prime examples being the transverse momentum of the singlet, and $\phi^*$ in DrellYan pair production. We derive a resummation formula valid up to nexttonexttonexttoleadinglogaritmic accuracy for the considered observables. This formula reduces exactly to the customary resummation performed in impactparameter space in the known cases, and it also predicts the correct powerbehaved scaling of the cross section in the limit of small value of the observable. We show how this formalism is efficiently implemented by means of Monte Carlo techniques in a fully exclusive generator that allows one to apply arbitrary cuts on the Born variables for any colour singlet, as well as to automatically match the resummed results to fixedorder calculations. As a phenomenological application, we present stateoftheart predictions for the Higgsboson transversemomentum spectrum at the LHC at nexttonexttonexttoleadinglogarithmic accuracy matched to fixed nexttonexttoleading order.
Bizon, Wojciech
Monni, Pier Francesco
Re, Emanuele
Rottoli, Luca
Torrielli, Paolo
Sat, 27 May 2017 05:20:48 GMT
20170525
OUTP1705P
http://cds.cern.ch/record/2266049
17
05P

Leptonic Invariants, Neutrino MassOrdering and the Octant of $\theta_{23}$
http://cds.cern.ch/record/2265766
We point out that leptonic weakbasis invariants are an important tool for the study of the properties of lepton flavour models. In particular, we show that appropriately chosen invariants can give a clear indication of whether a particular lepton flavour model favours normal or inverted hierarchy for neutrino masses and what is the octant of $\theta_{23}$. These invariants can be evaluated in any conveniently chosen weakbasis and can also be expressed in terms of neutrino masses, charged lepton masses, mixing angles and CP violation phases.
Branco, G.C.
Rebelo, M.N.
SilvaMarcos, J.I.
Wed, 24 May 2017 05:37:02 GMT
20170522
CERNTH2017075
http://cds.cern.ch/record/2265766
2017
075

Update on lepton nonuniversality in exclusive $b\to s \ell\ell$ decays
http://cds.cern.ch/record/2265053
The LHCb measurements of certain ratios of decay modes testing lepton flavour nonuniversality might open an exciting world of new physics beyond the standard model. The latest LHCb measurements of R_K^* offer some new insight beyond the previous measurement of R_K. We work out the present significance for nonuniversality and demonstrate that only part of the luminosity of 50 fb^{1} that LHCb provides will be needed to offer soon a clear definite answer on the present question if we see a very small glimpse of lepton flavour nonuniversal new physics or not. We also update our previous predictions for other ratios based on our analysis of the present measurements of the ratios R_K^(*). We argue that claims of 5 sigma deviations from the SM based on all b to s l^+ l^ data including the ratios are misleading and at present still based on guesstimates of hadronic power corrections in the b to s l^+ l^ angular observables.
Hurth, T.
Mahmoudi, F.
Martinez Santos, D.
Neshatpour, S.
Thu, 18 May 2017 14:32:19 GMT
20170517
CERNTH2017110
http://cds.cern.ch/record/2265053
2017
110