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Integrating out lattice gauge fields
https://cds.cern.ch/record/2028555
The sign problem is a major obstacle to our understanding of the phase diagram of QCD at finite baryon density. Several numerical methods have been proposed to tackle this problem, but a full solution to the sign problem is still elusive. Motivated by this problem and by recent advances in diagrammatic Monte Carlo methods, we find a new exact representation of the partition function of pure lattice gauge theory that contains no link variables. This approach can be easily extended to include staggered fermions, and results in a diagrammatic representation of fermionic states as arrangements of monomers, dimers, and fermionic loops saturating the spacetime lattice. Our representations are exact for any value of the lattice coupling, and extend previous representations that are only valid in the strong coupling limit and at $O(\beta)$. As a concrete example, we construct a monomerdimerloop representation of compact lattice QED.
Vairinhos, Helvio
de Forcrand, Philippe
Fri, 26 Jun 2015 15:57:41 GMT
23 Jun 2015
arXiv:1506.07007
https://cds.cern.ch/record/2028555

Precise determination of the Higgs mass in supersymmetric models with vectorlike tops and the impact on naturalness in minimal GMSB
https://cds.cern.ch/record/2018135
We present a precise analysis of the Higgs mass corrections stemming from vectorlike top partners in supersymmetric models. We reduce the theoretical uncertainty compared to previous studies in the following aspects: (i) including the oneloop threshold corrections to SM gauge and Yukawa couplings due to the presence of the new states to obtain the $\bar{\text{DR}}$ parameters entering all loop calculations, (ii) including the full momentum dependence at oneloop, and (iii) including all twoloop corrections but the ones involving $g_1$ and $g_2$. We find that the additional threshold corrections are very important and can give the largest effect on the Higgs mass. However, we identify also parameter regions where the new twoloop effects can be more important than the ones of the MSSM and change the Higgs mass prediction by up to 10 GeV. This is for instance the case in the low $\tan\beta$, small $M_A$ regime. We use these results to calculate the electroweak finetuning of an UV complete variant of this model. For this purpose, we add a complete $\textbf{10}$ and $\bar{\textbf{10}}$ representation of $SU(5)$ to the MSSM particle content. We embed this model in minimal Gauge Mediated Supersymmetry Breaking and calculate the electroweak finetuning with respect to all important parameters. It turns out that the limit on the gluino mass becomes more important for the finetuning than the Higgs mass measurements which is easily to satisfy in this setup.
Nickel, Kilian
Staub, Florian
Mon, 25 May 2015 05:25:39 GMT
22 May 2015
arXiv:1505.06077
https://cds.cern.ch/record/2018135

Dark Matter from the Supersymmetric Custodial Triplet Model
https://cds.cern.ch/record/2008528
The Supersymmetric Custodial Triplet Model (SCTM) adds to the particle content of the MSSM three $SU(2)_L$ triplet chiral superfields with hypercharge $Y=(0,\pm1)$. At the superpotential level the model respects a global $SU(2)_L \otimes SU(2)_R$ symmetry only broken by the Yukawa interactions. The pattern of vacuum expectation values of the neutral doublet and triplet scalar fields depends on the symmetry pattern of the Higgs soft breaking masses. We study the cases where this symmetry is maintained in the Higgs sector, and when it is broken only by the two doublets attaining different vacuum expectation values. In the former case, the symmetry is spontaneously broken down to the vectorial subgroup $SU(2)_V$ and the $\rho$ parameter is protected by the custodial symmetry. However in both situations the $\rho$ parameter is protected at tree level, allowing for light triplet scalars with large vacuum expectation values. We find that over a large range of parameter space, a light neutralino can supply the correct relic abundance of dark matter either through resonant schannel triplet scalar funnels or well tempering of the Bino with the triplet fermions. Direct detection experiments have trouble probing these model points because the custodial symmetry suppresses the coupling of the neutralino and the $Z$ and a small Higgsino component of the neutralino suppresses the coupling with the Higgs. Likewise the annihilation cross sections for indirect detection lie below the FermiLAT upper bounds for the different channels.
Delgado, Antonio
GarciaPepin, Mateo
Ostdiek, Bryan
Quiros, Mariano
Mon, 13 Apr 2015 05:43:18 GMT
09 Apr 2015
arXiv:1504.02486
https://cds.cern.ch/record/2008528

CrossOrder Integral Relations from Maximal Cuts
https://cds.cern.ch/record/2003992
We study the ABDK relation using maximal cuts of one and twoloop integrals with up to five external legs. We show how to find a special combination of integrals that allows the relation to exist, and how to reconstruct the terms with oneloop integrals squared. The reconstruction relies on the observation that integrals across different loop orders can have support on the same generalized unitarity cuts and can share global poles. We discuss the appearance of nonhomologous integration contours in multivariate residues. Their origin can be understood in simple terms, and their existence enables us to distinguish contributions from different integrals. Our analysis suggests that maximal and nearmaximal cuts can be used to infer the existence of integral identities more generally.
Johansson, Henrik
Kosower, David A
Larsen, Kasper J
Sogaard, Mads
Wed, 25 Mar 2015 17:35:58 GMT
23 Mar 2015
arXiv:1503.06711
https://cds.cern.ch/record/2003992

Higgs boson gluonfusion production in N3LO QCD
https://cds.cern.ch/record/2003776
We present the crosssection for the production of a Higgs boson at hadroncolliders at nextto nexttonexttoleading order (N3LO) in perturbative QCD. The calculation is based on a method to perform a series expansion of the partonic crosssection around the threshold limit to an arbitrary order. We perform this expansion to sufficiently high order to obtain the value of the hadronic cross at N3LO in the large topmass limit. For renormalisation and factorisation scales equal to half the Higgs mass, the N3LO corrections are of the order of +2.2%. The total scale variation at N3LO is 3%, reducing the uncertainty due to missing higher order QCD corrections by a factor of three.
Anastasiou, Charalampos
Duhr, Claude
Dulat, Falko
Herzog, Franz
Mistlberger, Bernhard
Wed, 25 Mar 2015 17:10:36 GMT
20 Mar 2015
arXiv:1503.06056
https://cds.cern.ch/record/2003776

Constraining Dark Sectors with Monojets and Dijets
https://cds.cern.ch/record/2003772
We consider dark sector particles (DSPs) that obtain sizeable interactions with Standard Model fermions from a new mediator. While these particles can avoid observation in direct detection experiments, they are strongly constrained by LHC measurements. We demonstrate that there is an important complementarity between searches for DSP production and searches for the mediator itself, in particular bounds on (broad) dijet resonances. This observation is crucial not only in the case where the DSP is all of the dark matter but whenever  precisely due to its sizeable interactions with the visible sector  the DSP annihilates away so efficiently that it only forms a dark matter subcomponent. To highlight the different roles of DSP direct detection and LHC monojet and dijet searches, as well as perturbativity constraints, we first analyse the exemplary case of an axialvector mediator and then generalise our results. We find important implications for the interpretation of LHC dark matter searches in terms of simplified models.
Chala, Mikael
Kahlhoefer, Felix
McCullough, Matthew
Nardini, Germano
SchmidtHoberg, Kai
Wed, 25 Mar 2015 17:10:31 GMT
19 Mar 2015
arXiv:1503.05916
https://cds.cern.ch/record/2003772

Doubly SelfDual Actions in Various Dimensions
https://cds.cern.ch/record/2003678
The selfduality of the N=1 supersymmetric BornInfeld action implies a double selfduality of the tensor multiplet squareroot action when the scalar and the antisymmetric tensor are interchanged via Poincare' duality. We show how this phenomenon extends to D spacetime dimensions for nonlinear actions involving pairs of forms of rank p and Dp2. As a byproduct, we construct a new twofield generalization of the BornInfeld action whose equations of motion are invariant under a U(1) duality. In these systems, the introduction of GreenSchwarz terms results in explicit nonlinear masslike terms for dual massive pairs.
Ferrara, S
Sagnotti, A
Yeranyan, A
Wed, 25 Mar 2015 17:07:10 GMT
16 Mar 2015
arXiv:1503.04731
https://cds.cern.ch/record/2003678

Addressing the LHC flavour anomalies with horizontal gauge symmetries
https://cds.cern.ch/record/2001333
We study the impact of an additional $U(1)'$ gauge symmetry with flavourdependent charges for quarks and leptons on the LHC flavour anomalies observed in $B \to K^* \mu^+\mu^$, $R(K) = B \to K \mu^+\mu^/B \to K e^+e^$, and $h \to \mu\tau$. In its minimal version with two scalar doublets, the resulting model naturally explains the deviations from the Standard Model observed in $B \to K^* \mu^+\mu^$ and $R(K)$. The CMS access in $h \to \mu\tau$ can be explained by introducing a third scalar doublet, which gives rise to a prediction for $\tau \to 3\mu$. We investigate constraints from flavour observables and direct LHC searches for $pp \to Z' \to \mu^+\mu^$. Our model successfully generates the measured fermionmixing matrices and does not require vectorlike fermions, unlike previous attempts to explain these anomalies.
Crivellin, Andreas
D'Ambrosio, Giancarlo
Heeck, Julian
Fri, 13 Mar 2015 06:51:08 GMT
11 Mar 2015
arXiv:1503.03477
https://cds.cern.ch/record/2001333

Light stops, blind spots, and isospin violation in the MSSM
https://cds.cern.ch/record/2001258
In the framework of the MSSM, we examine several simplified models where only a few superpartners are light. This allows us to study WIMPnucleus scattering in terms of a handful of MSSM parameters and thereby scrutinize their impact on dark matter directdetection experiments. Focusing on spinindependent WIMPnucleon scattering, we derive simplified, analytic expressions for the Wilson coefficients associated with Higgs and squark exchange. We utilize these results to study the complementarity of constraints due to directdetection, flavor, and collider experiments. We also identify parameter configurations that produce (almost) vanishing cross sections. In the proximity of these socalled blind spots, we find that the amount of isospin violation may be much larger than typically expected in the MSSM. This feature is a generic property of parameter regions where cross sections are suppressed, and highlights the importance of a careful analysis of the nucleon matrix elements and the associated hadronic uncertainties. This becomes especially relevant once the increased sensitivity of future directdetection experiments corners the MSSM into these regions of parameter space.
Crivellin, Andreas
Hoferichter, Martin
Procura, Massimiliano
Tunstall, Lewis C
Fri, 13 Mar 2015 06:48:47 GMT
11 Mar 2015
arXiv:1503.03478
https://cds.cern.ch/record/2001258

On stability of electroweak vacuum during inflation
https://cds.cern.ch/record/2000570
We study ColemanDe Luccia tunneling of the Standard Model Higgs field during inflation in the case when the electroweak vacuum is metastable. We verify that the tunneling rate is exponentially suppressed. The main contribution to the suppression is the same as in flat spacetime. We analytically estimate the corrections due to the expansion of the universe and an effective mass term in the Higgs potential that can be present at inflation.
Shkerin, Andrey
Sibiryakov, Sergey
Wed, 11 Mar 2015 06:48:04 GMT
06 Mar 2015
arXiv:1503.02586
https://cds.cern.ch/record/2000570

Signatures of Majorana dark matter with tchannel mediators
https://cds.cern.ch/record/1999386
Three main strategies are being pursued to search for nongravitational dark matter signals: direct detection, indirect detection and collider searches. Interestingly, experiments have reached sensitivities in these three search strategies which may allow detection in the near future. In order to take full benefit of the wealth of experimental data, and in order to confirm a possible dark matter signal, it is necessary to specify the nature of the dark matter particle and of the mediator to the Standard Model. In this paper, we focus on a simplified model where the dark matter particle is a Majorana fermion that couples to a light Standard Model fermion via a Yukawa coupling with a scalar mediator. We review the observational signatures of this model and we discuss the complementarity among the various search strategies, with emphasis in the well motivated scenario where the dark matter particles are produced in the early Universe via thermal freezeout.
Garny, Mathias
Ibarra, Alejandro
Vogl, Stefan
Sat, 07 Mar 2015 06:51:30 GMT
04 Mar 2015
arXiv:1503.01500
https://cds.cern.ch/record/1999386

Froissart Bound on Inelastic Cross Section Without Unknown Constants
https://cds.cern.ch/record/1997117
Assuming that axiomatic local field theory results hold for hadron scattering, Andr\'e Martin and S. M. Roy recently obtained absolute bounds on the Dwave below threshold for pionpion scattering and thereby determined the scale of the logarithm in the Froissart bound on total cross sections in terms of pion mass only. Previously, Martin proved a rigorous upper bound on the inelastic crosssection $\sigma_{inel}$ which is onefourth of the corresponding upper bound on $\sigma_{tot}$, and Wu, Martin,Roy and Singh improved the bound by adding the constraint of a given $\sigma_{tot}$. Here we use unitarity and analyticity to determine, without any high energy approximation, upper bounds on energy averaged inelastic cross sections in terms of low energy data in the crossed channel. These are Froissarttype bounds without any unknown coefficient or unknown scale factors and can be tested experimentally. Alternatively, their asymptotic forms,together with the MartinRoy absolute bounds on pionpion Dwaves below threshold, yield absolute bounds on energyaveraged inelastic cross sections. E.g. for $\pi^0 \pi^0$ scattering, defining $\sigma_{inel}=\sigma_{tot} \big (\sigma^{\pi^0 \pi^0 \rightarrow \pi^0 \pi^0} + \sigma^{\pi^0 \pi^0 \rightarrow \pi^+ \pi^} \big )$,we show that for c.m. energy $\sqrt{s}\rightarrow \infty $, $\bar{\sigma}_{inel }(s,\infty)\equiv s\int_{s} ^{\infty } ds'\sigma_{inel }(s')/s'^2 \leq (\pi /4) (m_{\pi })^{2} [\ln (s/s_1)+(1/2)\ln \ln (s/s_1) +1]^2$ where $1/s_1= 34\pi \sqrt{2\pi }\>m_{\pi }^{2} $ . This bound is asymptotically onefourth of the corresponding MartinRoy bound on the total cross section, and the scale factor $s_1$ is onefourth of the scale factor in the total cross section bound. The average over the interval (s,2s) of the inelastic $\pi^0 \pi^0 $cross section has a bound of the same form with $1/s_1$ replaced by $1/s_2=2/s_1 $.
Martin, AndrĂ©
Roy, S M
Thu, 05 Mar 2015 07:11:16 GMT
04 Mar 2015
arXiv:1503.01261
https://cds.cern.ch/record/1997117

Emerging Jets
https://cds.cern.ch/record/1993313
In this work, we propose a novel search strategy for new physics at the LHC that utilizes calorimeter jets that (i) are composed dominantly of displaced tracks and (ii) have many different vertices within the jet cone. Such emerging jet signatures are smoking guns for models with a composite dark sector where a parton shower in the dark sector is followed by displaced decays of dark pions back to SM jets. No current LHC searches are sensitive to this type of phenomenology. We perform a detailed simulation for a benchmark signal with two regular and two emerging jets, and present and implement strategies to suppress QCD backgrounds by up to six orders of magnitude. At the 14 TeV LHC, this signature can be probed with mediator masses as large as 1.5 TeV for a range of dark pion lifetimes, and the reach is increased further at the highluminosity LHC. The emerging jet search is also sensitive to a broad class of longlived phenomena, and we show this for a supersymmetric model with Rparity violation. Possibilities for discovery at LHCb are also discussed.
Schwaller, Pedro
Stolarski, Daniel
Weiler, Andreas
Fri, 20 Feb 2015 08:33:38 GMT
18 Feb 2015
arXiv:1502.05409
https://cds.cern.ch/record/1993313

Robust collider limits on heavymediator Dark Matter
https://cds.cern.ch/record/1992767
We discuss how to consistently use Effective Field Theories (EFTs) to set universal bounds on heavymediator Dark Matter at colliders, without prejudice on the model underlying a given effective interaction. We illustrate the method for a Majorana fermion, universally coupled to the Standard Model quarks via a dimension6 axialaxial fourfermion operator. We recast the ATLAS monojet analysis and show that a considerable fraction of the parameter space, seemingly excluded by a na\"ive EFT interpretation, is actually still unexplored. Consistently set EFT limits can be reinterpreted in any specific underlying model. We provide two explicit examples for the chosen operator and compare the reach of our modelindependent method with that obtainable by dedicated analyses.
Racco, Davide
Wulzer, Andrea
Zwirner, Fabio
Wed, 18 Feb 2015 06:43:42 GMT
16 Feb 2015
arXiv:1502.04701
https://cds.cern.ch/record/1992767

$D^6 R^4$ amplitudes in various dimensions
https://cds.cern.ch/record/1989347
Fourgraviton couplings in the low energy effective action of type II string vacua compactified on tori are strongly constrained by supersymmetry and Uduality. While the $R^4$ and $D^4 R^4$ couplings are known exactly in terms of LanglandsEisenstein series of the Uduality group, the $D^6 R^4$ couplings are not nearly as well understood. Exploiting the coincidence of the Uduality group in $D=6$ with the Tduality group in $D=5$, we propose an exact formula for the $D^6 R^4$ couplings in type II string theory compactified on $T^4$, in terms of a genustwo modular integral plus a suitable Eisenstein series. The same modular integral computes the twoloop correction to $D^6 R^4$ in 5 dimensions, but here provides the nonperturbative completion of the known perturbative terms in $D=6$. This proposal hinges on a systematic reanalysis of the weak coupling and large radius of the $D^6 R^4$ in all dimensions $D\geq 3$, which fills in some gaps and resolves some inconsistencies in earlier studies.
Pioline, Boris
Fri, 13 Feb 2015 06:37:29 GMT
11 Feb 2015
arXiv:1502.03377
https://cds.cern.ch/record/1989347

Spot the stop with a btag
https://cds.cern.ch/record/1987870
The LHC searches for light compressed stop squarks have resulted in considerable bounds in the case where the stop decays to a neutralino and a charm quark. However, in the case where the stop decays to a neutralino, a bottom quark and two fermions via an offshell Wboson, there is currently a significant unconstrained region in the stopneutralino mass plane, still allowing for stop masses in the range 90140 GeV. In this paper we propose a new monojetlike search for light stops, optimized for the fourbody decay mode, in which at least one btagged jet is required. We show that, already by using the existing 8 TeV LHC data set, such a search would cover the entire unconstrained region. Moreover, in the process of validating our tools against an ATLAS monojet search, we show that the existing limit can be extended to exclude also stop masses below 100 GeV.
Ferretti, Gabriele
Franceschini, Roberto
Petersson, Christoffer
Torre, Riccardo
Tue, 10 Feb 2015 07:06:43 GMT
05 Feb 2015
arXiv:1502.01721
https://cds.cern.ch/record/1987870

Massive BornInfeld and Other Dual Pairs
https://cds.cern.ch/record/1987236
We consider massive dual pairs of pforms and (Dp1)forms described by nonlinear Lagrangians, where nonlinear curvature terms in one theory translate into nonlinear masslike terms in the dual theory. In particular, for D=2p and p even the two nonlinear structures coincide when the nonlinear massless theory is selfdual. This state of affairs finds a natural realization in the fourdimensional massive N=1 supersymmetric BornInfeld action, which describes either a massive vector multiplet or a massive linear (tensor) multiplet with a BornInfeld masslike term. These systems should play a role for the massive gravitino multiplet obtained from a partial superHiggs in N=2 Supergravity.
Ferrara, S
Sagnotti, A
Fri, 06 Feb 2015 06:58:50 GMT
05 Feb 2015
arXiv:1502.01650
https://cds.cern.ch/record/1987236

The Flavour Portal to Dark Matter
https://cds.cern.ch/record/1983871
We present a class of models in which dark matter (DM) is a fermionic singlet under the Standard Model (SM) gauge group but is charged under a symmetry of flavour that acts as well on the SM fermions. Interactions between DM and SM particles are mediated by the scalar fields that spontaneously break the flavour symmetry, the socalled flavons. In the case of gauged flavour symmetries, the interactions are also mediated by the flavour gauge bosons. We first discuss the construction and the generic features of this class of models. Then a concrete example with an abelian flavour symmetry is considered. We compute the complementary constraints from the relic abundance, direct detection experiments and flavour observables, showing that wide portions of the parameter space are still viable. Other possibilities like nonabelian flavour symmetries can be analysed within the same framework.
Calibbi, Lorenzo
Crivellin, Andreas
Zaldivar, Bryan
Fri, 30 Jan 2015 07:57:45 GMT
28 Jan 2015
arXiv:1501.07268
https://cds.cern.ch/record/1983871

Higgs boson decay into bquarks at NNLO accuracy
https://cds.cern.ch/record/1983867
We compute the fully differential decay rate of the Standard Model Higgs boson into bquarks at nexttonexttoleading order (NNLO) accuracy in alpha_S. We employ a general subtraction scheme developed for the calculation of higher order perturbative corrections to QCD jet cross sections, which is based on the universal infrared factorization properties of QCD squared matrix elements. We show that the subtractions render the various contributions to the NNLO correction finite. In particular, we demonstrate analytically that the sum of integrated subtraction terms correctly reproduces the infrared poles of the twoloop double virtual contribution to this process. We present illustrative differential distributions obtained by implementing the method in a parton level Monte Carlo program. The basic ingredients of our subtraction scheme, used here for the first time to compute a physical observable, are universal and can be employed for the computation of more involved processes.
Del Duca, Vittorio
Duhr, Claude
Somogyi, Gabor
Tramontano, Francesco
Trocsanyi, Zoltan
Fri, 30 Jan 2015 07:57:44 GMT
28 Jan 2015
arXiv:1501.07226
https://cds.cern.ch/record/1983867

Neutrino versus antineutrino cross sections and CP violation
https://cds.cern.ch/record/1981097
We discuss the nuclear interactions of neutrinos versus those of antineutrinos, a relevant comparison for CP violation experiments in the neutrino sector. We consider the MiniBooNE quasielasticlike double differential neutrinos and antineutrinos cross sections which are flux dependent and hence specific to the MiniBooNE setup. We combine them introducing their sum and their difference. We show that the last combination can bring a general information, which can be exploited in other experiments, on the nuclear matrix elements of the axial vector interference term. Our theoretical model reproduces well the two cross sections combinations. This confirms the need for a sizeable multinucleon component in particular in the interference term.
Ericson, M
Martini, M
Wed, 14 Jan 2015 06:26:23 GMT
11 Jan 2015
arXiv:1501.02442
https://cds.cern.ch/record/1981097

Wallcrossing made smooth
https://cds.cern.ch/record/1980359
In $D=4,N=2$ theories on $R^{3,1}$, the index receives contributions not only from singleparticle BPS states, counted by the BPS indices, but also from multiparticle states made of BPS constituents. In a recent work [arXiv:1406.2360], a general formula expressing the index in terms of the BPS indices was proposed, which is smooth across walls of marginal stability and reproduces the expected singleparticle contributions. In this note, I analyze the twoparticle contributions predicted by this formula, and show agreement with the spectral asymmetry of the continuum of scattering states in the supersymmetric quantum mechanics of two nonrelativistic, mutually nonlocal dyons. This provides a physical justification for the error function profile used in the mathematics literature on indefinite theta series, and in the physics literature on black hole partition functions.
Pioline, Boris
Fri, 09 Jan 2015 07:08:58 GMT
07 Jan 2015
arXiv:1501.01643
https://cds.cern.ch/record/1980359

Explaining $h\to\mu^\pm\tau^\mp$, $B\to K^* \mu^+\mu^$ and $B\to K \mu^+\mu^/B\to K e^+e^$ in a twoHiggsdoublet model with gauged $L_\muL_\tau$
https://cds.cern.ch/record/1980012
The LHC observed so far three deviations from the Standard Model (SM) predictions in flavour observables: LHCb reported anomalies in $B\to K^* \mu^+\mu^$ and $R(K)=B\to K \mu^+\mu^/B\to K e^+e^$ while CMS found an excess in $h\to\mu\tau$. We show, for the first time, how these deviations from the SM can be explained within a single wellmotivated model: a twoHiggsdoublet model with gauged $L_\muL_\tau$ symmetry. We find that, despite the constraints from $\tau\to\mu\mu\mu$ and $B_s$$\overline{B}_s$ mixing, one can explain $h \to\mu\tau$, $B\to K^* \mu^+\mu^$ and $R(K)$ simultaneously, obtaining interesting correlations among the observables.
Crivellin, Andreas
D'Ambrosio, Giancarlo
Heeck, Julian
Wed, 07 Jan 2015 08:01:17 GMT
05 Jan 2015
arXiv:1501.00993
https://cds.cern.ch/record/1980012

LHC constraints on gauge boson couplings to dark matter
https://cds.cern.ch/record/1979702
Collider searches for energetic particles recoiling against missing transverse energy allow to place strong bounds on the interactions between dark matter (DM) and standard model particles. In this article we update and extend LHC constraints on effective dimension7 operators involving DM and electroweak gauge bosons. A concise comparison of the sensitivity of the monophoton, monoW, monoZ, monoW/Z, invisible Higgsboson decays in the vector boson fusion mode and the monojet channel is presented. Depending on the parameter choices, either the monophoton or the monojet data provide the most stringent bounds at the moment. We furthermore explore the potential of improving the current 8 TeV limits at 14 TeV. Future strategies capable of disentangling the effects of the different effective operators involving electroweak gauge bosons are discussed as well.
Crivellin, Andreas
Haisch, Ulrich
Hibbs, Anthony
Tue, 06 Jan 2015 06:25:40 GMT
05 Jan 2015
arXiv:1501.00907
https://cds.cern.ch/record/1979702

Observable Effects of General New Scalar Particles
https://cds.cern.ch/record/1979299
We classify all possible new scalar particles that can have renormalizable linear couplings to Standard Model fields and therefore be singly produced at colliders. We show that this classification exhausts the list of heavy scalar particles that contribute at the tree level to the Standard Model effective Lagrangian to dimension six. We compute this effective Lagrangian for a general scenario with an arbitrary number of new scalar particles and obtain flavorpreserving constraints on their couplings and masses. This completes the treelevel matching of the coefficients of dimension five and six operators in the effective Lagrangian to arbitrary extensions of the Standard Model.
de Blas, Jorge
Chala, Mikael
PerezVictoria, Manuel
Santiago, Jose
Wed, 31 Dec 2014 07:01:44 GMT
29 Dec 2014
arXiv:1412.8480
https://cds.cern.ch/record/1979299

Automated NNLL+NLO Resummation for JetVeto Cross Sections
https://cds.cern.ch/record/1979152
In electroweakboson production processes with a jet veto, higherorder corrections are enhanced by logarithms of the veto scale over the invariant mass of the boson system. In this paper, we resum these Sudakov logarithms at nexttonexttoleading logarithmic (NNLL) accuracy and match our predictions to nexttoleading order (NLO) fixedorder results. We perform the calculation in an automated way, for arbitrary electroweak final states and in the presence of kinematic cuts on the leptons produced in the decays of the electroweak bosons. The resummation is based on a factorization theorem for the cross sections into hard functions, which encode the virtual corrections to the boson production process, and beam functions, which describe the lowp_T emissions collinear to the beams. The oneloop hard functions for arbitrary processes are calculated using the MadGraph5_aMC@NLO framework, while the beam functions are process independent. We perform the resummation for a variety of processes, in particular for W+W pair production followed by leptonic decays of the W bosons.
Becher, Thomas
Frederix, Rikkert
Neubert, Matthias
Rothen, Lorena
Tue, 30 Dec 2014 06:25:03 GMT
29 Dec 2014
arXiv:1412.8408
https://cds.cern.ch/record/1979152