HEP Phenomenology·hep-ph

Fri·Oct 30, 2015Friday·October 30, 2015

38 papers—28 primary·10 cross-listed·reconstructed*

01*
The impact of the intrinsic charm quark content of the proton on differential $γ + c$ cross section
S. Rostami · A. Khorramian · A. Aleedaneshvar
We present a comparative analysis of the impact of the non-perturbative intrinsic charm quark content of the proton on differential cross section of $γ + c$ -jet in $pp$ and $p p ˉ$ collisions, for the kinematic regions that are sensitive to this contribution. We discuss the $Q^{2}$ evolution of intrinsic quark distributions and present a code which provide these distributions as a function of $x$ and $Q^{2}$ for any arbitrary Fock state probability. For the $p p ˉ$ collisions at the Tevatron, the results are compared with the recent experimental data of D0 at $s = 1.96$ TeV and also predictions for $pp$ collisions at $s = 8$ TeV and $s = 13$ TeV for the LHC.
hep-phhep-exJ.Phys.G(2016)·26 citations
02*
Precision Diboson Observables for the LHC
Christopher Frye🇺🇸 · Marat Freytsis🇺🇸 · Jakub Scholtz🇺🇸 · Matthew J. Strassler🇺🇸
Motivated by the restoration of $S U (2) \times U (1)$ at high energy, we suggest that certain ratios of diboson differential cross sections can be used as high-precision observables at the LHC. We rewrite leading-order diboson partonic cross sections in a form that makes their $S U (2) \times U (1)$ and custodial $S U (2)$ structure more explicit than in previous literature, and identify important aspects of this structure that survive even in hadronic cross sections. We then focus on higher-order corrections to ratios of $γ γ$ , $Z γ$ and $Z Z$ processes, including full next-to-leading-order corrections and $g g$ initial-state contributions, and argue that these ratios can likely be predicted to better than $5%$ , which should make them useful in searches for new phenomena. The ratio of $Z γ$ to $γ γ$ is especially promising in the near term, due to large rates and to exceptional cancellations of QCD-related uncertainties. We argue that electroweak corrections are moderate in size, have small uncertainties, and can potentially be observed in these ratios in the long run.
hep-phhep-exJHEP(2016)·26 citations
03*
Glueball Decay in the Witten-Sakai-Sugimoto Model and Finite Quark Masses
Frederic Brünner🇦🇹 · Anton Rebhan🇦🇹
We discuss recent results on the calculation of glueball decay rates in the Witten-Sakai-Sugimoto model, which favor the $f_{0} (1710)$ meson as a glueball candidate. The flavor asymmetric decay of $f_{0} (1710)$ is frequently attributed to a putative chiral suppression in glueball decays, which is however questionable in view of the large constituent quark masses induced by chiral symmetry breaking. We find that this can be explained by what we call nonchiral enhancement when finite quark masses are included in the holographic model, with good quantitative agreement with experimental data for $f_{0} (1710)$ . Assuming the latter to indeed be a nearly pure glueball, the model makes essentially parameter-free and thus falsifiable predictions for its decay rates involving vector mesons and an upper limit on the $η η^{'}$ decay rate.
hep-phhep-thnucl-thPoS(2015)·2 citations
04*
Measuring Vacuum Polarisation with High Power Lasers
B. King🇬🇧 · T. Heinzl🇬🇧
When exposed to intense electromagnetic fields, the quantum vacuum is expected to exhibit properties of a polarisable medium akin to a weakly nonlinear dielectric material. Various schemes have been proposed to measure such vacuum polarisation effects using a combination of high power lasers. Motivated by several planned experiments, we provide an overview of experimental signatures that have been suggested to confirm this prediction of quantum electrodynamics of real photon-photon scattering.
hep-phphysics.opticsphysics.plasm-phHigh Power Laser Sci.Eng.(2016)·154 citations
05*
The Singular Behavior of Jet Substructure Observables
Andrew J. Larkoski🇺🇸 · Ian Moult🇺🇸
Jet substructure observables play a central role at the Large Hadron Collider for identifying the boosted hadronic decay products of electroweak scale resonances. The complete description of these observables requires understanding both the limit in which hard substructure is resolved, as well as the limit of a jet with a single hard core. In this paper we study in detail the perturbative structure of two prominent jet substructure observables, $N$ -subjettiness and the energy correlation functions, as measured on background QCD jets. In particular, we focus on the distinction between the limits in which two-prong structure is resolved or unresolved. Depending on the choice of subjet axes, we demonstrate that at fixed order, $N$ -subjettiness can manifest myriad behaviors in the unresolved region: smooth tails, end-point singularities, or singularities in the physical region. The energy correlation functions, by contrast, only have non-singular perturbative tails extending to the end point. We discuss the effect of hadronization on the various observables with Monte Carlo simulation and demonstrate that the modeling of these effects with non-perturbative shape functions is highly dependent on the $N$ -subjettiness axes definitions. Our study illustrates those regions of phase space that must be controlled for high-precision jet substructure calculations, and emphasizes how such calculations can be facilitated by designing substructure observables with simple singular structures.
hep-phhep-exPRD(2016)·23 citations
06*
Effective theories of universal theories
James D. Wells🇺🇸 · Zhengkang Zhang🇺🇸
It is well-known but sometimes overlooked that constraints on the oblique parameters (most notably $S$ and $T$ parameters) are generally speaking only applicable to a special class of new physics scenarios known as universal theories. In the effective field theory (EFT) framework, the oblique parameters should not be associated with Wilson coefficients in a particular operator basis, unless restrictions have been imposed on the EFT so that it describes universal theories. We work out these restrictions, and present a detailed EFT analysis of universal theories. We find that at the dimension-6 level, universal theories are completely characterized by 16 parameters. They are conveniently chosen to be: 5 oblique parameters that agree with the commonly-adopted ones, 4 anomalous triple-gauge couplings, 3 rescaling factors for the $h^{3}$ , $h f f$ , $hV V$ vertices, 3 parameters for $hV V$ vertices absent in the Standard Model, and 1 four-fermion coupling of order $y_{f}^{2}$ . All these parameters are defined in an unambiguous and basis-independent way, allowing for consistent constraints on the universal theories parameter space from precision electroweak and Higgs data.
hep-phJHEP(2016)·103 citations
07*
Measuring the signal strength in ttH with H->bb
Niccolo Moretti🇨🇭 · Petar Petrov🇬🇧 · Stefano Pozzorini🇨🇭 · Michael Spannowsky🇬🇧
A precise measurement of the Higgs boson couplings to bottom and top quarks is of paramount importance during the upcoming LHC runs. We present a comprehensive analysis for the Higgs production process in association with a semi-leptonically decaying top-quark pair and subsequent Higgs boson decay into bottom quarks. Due to the highly complex final state and large Standard Model backgrounds, measuring the signal strength in this process is known to be challenging. To maximise the sensitivity, we analyse different, statistically independent, phase space regions, where one or more of the heavy resonances are boosted. This allows us to employ jet substructure techniques, which help to reduce large tt+X backgrounds. We find that combining several ttH(bb) phase space regions will allow one to measure deviations of the Standard Model signal strength of order 20% with 3 ab^{-1}.
hep-phhep-exPRD(2016)·26 citations
08*
Saturation and geometrical scaling -- from small $x$ deep inelastic ep scattering to high energy proton-proton and heavy ion collisions
Michal Praszalowicz🇵🇱
Gluon distributions of colliding hadrons saturate as a result of the non-linear evolution equations of QCD. As a consequence there exists the so called saturation momentum, which is related to the gluon density per unit rapidity per transverse area. When saturation momentum is the only scale for physical processes, different observables exhibit geometrical scaling (GS). We show a number of examples of GS and its violation in different reactions.
hep-phnucl-thPoS(2015)·2 citations
09*
Exploring holographic Composite Higgs models
Djuna Croon🇬🇧 · Barry M. Dillon🇬🇧 · Stephan J. Huber🇬🇧 · Veronica Sanz🇬🇧
Simple Composite Higgs models predict new vector-like fermions not too far from the electroweak scale, yet LHC limits are now sensitive to the TeV scale. Motivated by this tension, we explore the holographic dual of the minimal model, MCHM5, to understand how far naive 4D predictions are from their 5D duals. Interestingly, we find that the usual hierarchy among the vector-like quarks is not generic, hence ameliorating the tuning issue. We find that lowering the UV cutoff in the 5D picture allows for heavier top partners, while keeping the mass of the Higgs boson at its observed value. In the 4D dual this corresponds to increasing the number of colours. This is essentially a Little Randall-Sundrum Model, which are known to reduce some flavour and electroweak constraints. Furthermore, in anticipation of the ongoing efforts at the LHC to put bounds on the top Yukawa, we demonstrate that deviations from the SM can be suppressed or enhanced with respect to what is expected from mere symmetry arguments in 4D. We conclude that the 5D holographic realisation of the MCHM5 with a small UV cutoff is not in tension with the current experimental data.
hep-phJHEP(2016)·27 citations
10*
Affleck-Dine leptogenesis and its backreaction to inflaton dynamics
Masaki Yamada🇯🇵
We investigate the backreaction of the Affleck-Dine leptogenesis to inflaton dynamics in the F-term hybrid and chaotic inflation models in supergravity. We determine the lightest neutrino mass in both models so that the predictions of spectral index, tensor-to-scalar ratio, and baryon abundance are consistent with observations.
hep-phastro-ph.COPLB(2016)·3 citations
11*
$Z_{2}$ SIMP Dark Matter
Nicolas Bernal🇧🇷 · Xiaoyong Chu🇮🇹
Dark matter with strong self-interactions provides a compelling solution to several small-scale structure puzzles. Under the assumption that the coupling between dark matter and the Standard Model particles is suppressed, such strongly interacting massive particles (SIMPs) allow for a successful thermal freeze-out through N-to-N' processes, where N dark matter particles annihilate to N' of them. In the most common scenarios, where dark matter stability is guaranteed by a $Z_{2}$ symmetry, the seemingly leading annihilating channel, i.e. 3-to-2 process, is forbidden, so the 4-to-2 one dominate the production of the dark matter relic density. Moreover, cosmological observations require that the dark matter sector is colder than the thermal bath of Standard Model particles, a condition that can be dynamically generated via a small portal between dark matter and Standard Model particles, à la freeze-in. This scenario is exemplified in the context of the Singlet Scalar dark matter model.
hep-phJCAP(2016)·144 citations
12*
Hints of a PeV Scale Supersymmetric Neutrino Sector: Neutrino Masses, Dark Matter, keV and PeV Anomalies
Bibhushan Shakya🇺🇸 · Samuel B. Roland🇺🇸 · James D. Wells🇺🇸
Neutrino masses and light (keV-GeV) sterile neutrinos can arise naturally via a modified, low energy seesaw mechanism if the right-handed neutrinos are charged under a new symmetry broken by a PeV scale vacuum expectation value, presumably tied to supersymmetry breaking. The additional field content also allows for freeze-in production of sterile neutrino dark matter. This framework can accommodate the recently observed 3.5 keV X-ray line, while a straightforward extension of the framework, using the new symmetry and the PeV energy scale, can explain the PeV energy neutrino events at IceCube. Together, these can therefore be taken as hints of the existence of a PeV scale supersymmetric neutrino sector.
hep-phastro-ph.COastro-ph.HE1 citation
13*
Chiral Symmetry transition in the Linear Sigma Model with quarks: Counting effective QCD degrees of freedom from low to high temperature
Alejandro Ayala🇲🇽 · Jorge David Castano-Yepes🇲🇽 · J. J. Cobos-Martinez🇲🇽 · Saul Hernandez-Ortiz🇲🇽 · Ana Julia Mizher🇲🇽 · Alfredo Raya🇲🇽
We use the linear sigma model coupled to quarks, together with a plausible location of the critical end point (CEP), to study the chiral symmetry transition in the QCD phase diagram. We compute the effective potential at finite temperature and density up to the contribution of the ring diagrams, both in the low and high temperature limits, and use it to compute the pressure and the position of the CEP. In the high temperature regime, by comparing to results from extrapolated lattice data, we determine the model coupling constants. Demanding that the CEP remains in the same location when described in the high temperature limit, we determine again the couplings and the pressure for the low temperature regime. We show that this procedure gives an average description of the lattice QCD results for the pressure and that the change from the low to the high temperature domains in this quantity can be attributed to the change in the coupling constants which in turn we link to the change in the effective degrees of freedom.
hep-phhep-latnucl-thInt.J.Mod.Phys.A(2016)·10 citations
14*
Kinetic Freeze-out Spectra of Identified Particles Produced in p-Pb Collisions at root(sNN) = 5.02 TeV
Inam-ul Bashir🇮🇳 · Saeed Uddin🇮🇳
We study the transverse momentum spectra of identified pions, Kaons, protons and Lambdas produced at midrapidity (0 < y < 0.5)in most central p-Pb collisions at root(sNN) = 5.02 TeV in comparison with a Unified Statistical Thermal Freeze-out Model (USTFM). The measurements of pions are reported upto pT = 3 GeV, the kaons (K- + K+) are reported upto pT = 2.5 GeV, K0s is reported upto pT = 7 GeV and the baryons (protons and Lambdas) are reported upto pT = 3.5 GeV. A good agreement is seen between the calculated results and the experimental data points taken from the ALICE experiment. The transverse momentum spectra are found to be flatter for heavy particles than for light particles. Bulk freeze-out properties in terms of kinetic freezeout temperature and the transverse collective flow velocity are extracted from the fits of the transverse momentum spectra of these hadrons. The effect of resonance decay contributions has also been taken care of.
hep-phnucl-thJ.Exp.Theor.Phys.(2017)·6 citations
15*
Electroweak interaction of particles with accelerated matter and astrophysical applications
Maxim Dvornikov (IZMIRAN, Tomsk State University)🇷🇺
The description of physical processes in accelerated frames opens a window to numerous new phenomena. One can encounter these effects both in the subatomic world and on a macroscale. In the present work we review our recent results on the study of the electroweak interaction of particles with an accelerated background matter. In our analysis we choose the noninertial comoving frame, where matter is at rest. Our study is based on the solution of the Dirac equation, which exactly takes into account both the interaction with matter and the nonintertial effects. First, we study the interaction of ultrarelativistic neutrinos, electrons and quarks with the rotating matter. We consider the influence of the matter rotation on the resonance in neutrino oscillations and the generation of anomalous electric current of charged particles along the rotation axis. Then, we study the creation of neutrino-antineutrino pairs in a linearly accelerated matter. The applications of the obtained results for elementary particle physics and astrophysics are discussed.
hep-phastro-ph.HEgr-qchep-thin: Particle Physics at the Year of Light…·0 citations
16*
Softly Fine-Tuned Standard Model and the Scale of Inflation
Beste Korutlu🇹🇷
The direct coupling between the Higgs field and the spacetime curvature, if finely tuned, is known to stabilize the Higgs boson mass. The fine-tuning is soft because the Standard Model (SM) parameters are subject to no fine-tuning thanks to their independence from the Higgs-curvature coupling. This soft fine-tuning leaves behind a large vacuum energy $\propto Λ_{UV}^{4}$ which inflates the Universe with a Hubble rate $\propto Λ_{UV}$ , $Λ_{UV}$ being the SM ultraviolet boundary. This means that the tensor-to-scalar ratio inferred from cosmic microwave background polarization measurements by BICEP2, Planck and others lead to the determination of $Λ_{UV}$ . The exit from the inflationary phase, as usual, is accomplished via decays of the vacuum energy. Here we show that, identification of $Λ_{UV}$ with the inflaton, as a sliding UV scale upon the SM, respects the soft fine-tuning constraint and does not disrupt the stability of the SM Higgs boson.
hep-phgr-qchep-thMod.Phys.Lett.A(2015)·1 citation
17*
Polarized window for left-right symmetry and a right-handed neutrino at the Large Hadron-Electron Collider
Subhadeep Mondal🇮🇳 · Santosh Kumar Rai🇮🇳
The breaking of parity, a fundamental symmetry between left and right is best understood in the framework of left-right symmetric extension of the standard model. We show that the production of a heavy right-handed neutrino at the proposed Large Hadron-Electron Collider (LHeC) could give us the most simple and direct hint of the scale of this breaking in left-right symmetric theories. This production mode gives a lepton number violating signal with $Δ L = 2$ which is very clean and has practically no standard model background. We highlight that the right-handed nature of $W_{R}$ exchange which defines the left-right symmetric theories can be confirmed by using a polarized electron beam and also enhance the production rates with relatively lower beam energy.
hep-phPRD(2016)·36 citations
18*
Compositeness of the Delta(1232) resonance in pi N scattering
Takayasu Sekihara (Osaka U., Res. Ctr. Nucl. Phys.)🇯🇵 · Takashi Arai (KEK, Tsukuba)🇯🇵 · Junko Yamagata-Sekihara (Nat. Inst. Tech., Oshima Coll.)🇯🇵 · Shigehiro Yasui (Tokyo Inst. Tech.)🇯🇵
We evaluate the $π N$ compositeness of the $Δ (1232)$ resonance so as to clarify the internal structure of $Δ (1232)$ in terms of the $π N$ component. Here the compositeness is defined as contributions from two-body wave functions to the normalization of the total wave function and is extracted from the $π N$ scattering amplitude. In this study we employ the chiral unitary approach with the interaction up to the next-to-leading order plus a bare $Δ$ term in chiral perturbation theory and describe $Δ (1232)$ in an elastic $π N$ scattering. Fitting the $π N$ scattering amplitude to the solution of the partial wave analysis, we obtain a large real part of the $π N$ compositeness for $Δ (1232)$ comparable to unity and non-negligible imaginary part as well, with which we reconfirm the result in the previous study on the $π N$ compositeness for $Δ (1232)$ .
hep-phhep-exnucl-exnucl-thJPS Conf.Proc.(2016)·2 citations
19*
Pentaquark states in a diquark-triquark model
Ruilin Zhu🇨🇳 · Cong-Feng Qiao🇨🇳
The diquark-triquark model is used to explain charmonium-pentaquark states, i.e., $P_{c} (4380)$ and $P_{c} (4450)$ , which were observed recently by the LHCb collaboration. For the first time, we investigate the properties of the color attractive configuration of a triquark and we define a nonlocal light cone distribution amplitude for pentaquark states, where both diquark and triquark are not pointlike, but they have nonzero size. We establish an effective diquark-triquark Hamiltonian based on spin-orbital interaction. According to the Hamiltonian, we show that the minimum mass splitting between $\frac{5}{2}^{+}$ and $\frac{3}{2}^{-}$ is around $100$ ~MeV, which may naturally solve the challenging problem of small mass splitting between $P_{c} (4450)$ and $P_{c} (4380)$ . This helps to understand the peculiarities of $P_{c} (4380)$ with a broad decay width whereas $P_{c} (4450)$ has a narrow decay width. Based on the diquark-triquark model, we predict more pentaquark states, which will hopefully be measured in future experiments.
hep-phhep-exnucl-exPLB(2016)·169 citations
20*
Cancellation of Glauber gluon exchange in the double Drell-Yan process
Markus Diehl🇩🇪 · Jonathan R. Gaunt🇩🇪 · Daniel Ostermeier🇩🇪 · Peter Ploessl🇩🇪 · Andreas Schafer🇩🇪
An essential part of any factorisation proof is the demonstration that the exchange of Glauber gluons cancels for the considered observable. We show this cancellation at all orders for double Drell-Yan production (the double parton scattering process in which a pair of electroweak gauge bosons is produced) both for the integrated cross section and for the cross section differential in the transverse boson momenta. In the process of constructing this proof, we also revisit and clarify some issues regarding the Glauber cancellation argument and its relation to the rest of the factorisation proof for the single Drell-Yan process.
hep-phJHEP(2016)·96 citations
21*
Probing Models of Neutrino Masses via the Flavor Structure of the Mass Matrix
Shinya Kanemura🇯🇵 · Hiroaki Sugiyama🇯🇵
We discuss what kinds of combinations of Yukawa interactions can generate the Majorana neutrino mass matrix. We concentrate on the flavor structure of the neutrino mass matrix because it does not depend on details of the models except for Yukawa interactions while determination of the overall scale of the mass matrix requires to specify also the scalar potential and masses of new particles. Thus, models to generate Majorana neutrino mass matrix can be efficiently classified according to the combination of Yukawa interactions. We first investigate the case where Yukawa interactions with only leptons are utilized. Next, we consider the case with Yukawa interactions between leptons and gauge singlet fermions, which have the odd parity under the unbroken Z_2 symmetry. We show that combinations of Yukawa interactions for these cases can be classified into only three groups. Our classification would be useful for the efficient discrimination of models via experimental tests for not each model but just three groups of models.
hep-phPLB(2016)·12 citations
22*
Searching for hidden sector in multiparticle production at the LHC
Miguel-Angel Sanchis-Lozano🇪🇸 · Edward K. Sarkisyan-Grinbaum🇨🇭 · Salvador Moreno-Picot🇪🇸
We study the impact of a hidden sector beyond the Standard Model, e.g. a Hidden Valley model, on factorial moments and cumulants of multiplicity distributions in multiparticle production with a special emphasis on the prospects for LHC results.
hep-phPLB(2016)·7 citations
23*
NLO QCD and electroweak corrections to $Z + γ$ production with leptonic Z-boson decays
Ansgar Denner🇩🇪 · Stefan Dittmaier🇩🇪 · Markus Hecht🇩🇪 · Christian Pasold🇩🇪
The next-to-leading-order electroweak corrections to $pp \to l^{+} l^{-} / ν ˉ ν + γ + X$ production, including all off-shell effects of intermediate Z bosons in the complex-mass scheme, are calculated for LHC energies, revealing the typically expected large corrections of tens of percent in the TeV range. Contributions from quark-photon and photon-photon initial states are taken into account as well, but their impact is found to be moderate or small. Moreover, the known next-to-leading-order QCD corrections are reproduced. In order to separate hard photons from jets, both a quark-to-photon fragmentation function á la Glover/Morgan and Frixione's cone isolation are employed. The calculation is available in the form of Monte Carlo programs allowing for the evaluation of arbitrary differential cross sections. Predictions for integrated cross sections are presented for the LHC at 7 TeV, 8 TeV, and 14 TeV, and differential distributions are discussed at 14 TeV for bare muons and dressed leptons. Finally, we consider the impact of anomalous $Z Z γ$ and $Z γ γ$ couplings.
hep-phJHEP(2016)·76 citations
24*
Color Discriminant Variable to Separate Dijet Resonances at the LHC
Pawin Ittisamai🇺🇸 · R. Sekhar Chivukula🇺🇸 · Kirtimaan Mohan🇺🇸 · Elizabeth H. Simmons🇺🇸
A narrow resonance decaying to dijets could be discovered at the 14 TeV run of the LHC. To quickly identify its color structure in a model-independent manner, we introduced a method based on a color discriminant variable, determined from the measurements of the resonance's production cross section, mass and width. This talk introduces a more transparent theoretical formulation of the color discriminant variable that highlights its relationship to the branching ratios of the resonance into incoming and outgoing partons and to the properties of those partons. The formulation makes it easier to predict the value of the variable for a given class of resonance. We show that this method applies well to color-triplet and color-sextet scalar diquarks, distinguishing them clearly from other candidate resonances.
hep-ph0 citations
25*
A common origin of $R_{K}$ and neutrino masses
Heinrich Päs🇩🇪 · Erik Schumacher🇩🇪
The same leptoquarks that explain the recently observed anomaly in $R_{K}$ can generate naturally small Majorana neutrino masses at one-loop level through mixing with the standard model Higgs boson. This is particularly relevant in models with at least two leptoquarks contributing to $b \to s l l$ transitions.
hep-phPRD(2015)·72 citations
26*
The BMS Equation and c\bar{c} Production; A Comparison of the BMS and BK Equations
Giuseppe Marchesini🇮🇹 · A.H. Mueller🇺🇸
We introduce two processes where the BMS equation appears in a context quite different from the original context of non-global jet observables. We note the strong similarities of the BMS equation to the BK and FKPP equations and argue that these, essentially identical equations, can be viewed either in terms of the probability, or amplitude, of something not happening or in terms of the nonlinear terms setting unitarity limits. Mostly analytic solutions are given for (i) the probability that no $c c ˉ$ pairs be produced in a jet decay and (ii) the probability that no- $c c ˉ$ pairs be produced in a high energy dipole nucleus scattering. Both these processes obey BMS equations, albeit with very different kernels.
hep-phJHEP(2016)·5 citations
27*
New potentials for string axion inflation
Tatsuo Kobayashi🇯🇵 · Akane Oikawa🇯🇵 · Hajime Otsuka🇯🇵
We propose a new type of axion inflation with complex structure moduli in the framework of type IIB superstring theory compactified on Calabi-Yau manifold. The inflaton is identified as the axion for the complex structure moduli whose potential is originating from instantonic corrections appearing through the period vector of mirror Calabi-Yau manifold. The axionic shift symmetry is broken down to the discrete one by the inclusion of instantonic correction and certain three-from fluxes. Our proposed inflation scenario is compatible with Kähler moduli stabilization. We also study a typical reheating temperature in the case of complex structure moduli inflation.
hep-phastro-ph.COhep-thPRD(2016)·44 citations
28*
Looking for New Naturally Aligned Higgs Doublets at the LHC
P. S. Bhupal Dev🇬🇧 · Apostolos Pilaftsis🇬🇧
Since the current LHC Higgs data suggest the couplings of the observed 125 GeV Higgs boson to be close to the Standard Model (SM) expectations, any extended Higgs sector must lead to the so-called SM alignment limit, where one of the Higgs bosons behaves exactly like that of the SM. In the context of the Two Higgs Doublet Model (2HDM), this alignment is often associated with either decoupling of the heavy Higgs sector or accidental cancellations in the 2HDM potential. We present a novel symmetry justification for 'natural' alignment without necessarily decoupling or fine-tuning. We show that there exist only three different symmetry realizations of the natural alignment scenario in 2HDM. We analyze new collider signals for the heavy Higgs sector in the natural alignment limit, which dominantly lead to third-generation quarks in the final state and can serve as a useful observational tool during the Run-II phase of the LHC.
hep-phhep-exPoS(2015)·3 citations
29*
More on the properties of the first Gribov region in Landau gauge
Axel Maas🇦🇹
Complete gauge-fixing beyond perturbation theory in non-Abelian gauge theories is a non-trivial problem. This is particularly evident in covariant gauges, where the Gribov-Singer ambiguity gives an explicit formulation of the problem. In practice, this is a problem if gauge-dependent quantities between different methods, especially lattice and continuum methods, should be compared: Only when treating the Gribov-Singer ambiguity in the same way is the comparison meaningful. To provide a better basis for such a comparison the structure of the first Gribov region in Landau gauge, a subset of all possible gauge copies satisfying the perturbative Landau gauge condition, will be investigated. To this end, lattice gauge theory will be used to investigate a two-dimensional projection of the region for SU(2) Yang-Mills theory in two, three, and four dimensions for a wide range of volumes and discretizations.
↳ hep-lathep-phhep-thPRD(2016)·24 citations
30*
Opportunities With Decay-At-Rest Neutrinos From Decay-In-Flight Neutrino Beams
C. Grant🇺🇸 · B. R. Littlejohn🇺🇸
Neutrino beam facilities, like spallation neutron facilities, produce copious quantities of neutrinos from the decay at rest of mesons and muons. The viability of decay-in-flight neutrino beams as sites for decay-at-rest neutrino studies has been investigated by calculating expected low-energy neutrino fluxes from the existing Fermilab NuMI beam facility. Decay-at-rest neutrino production in NuMI is found to be roughly equivalent per megawatt to that of spallation facilities, and is concentrated in the facility's target hall and beam stop regions. Interaction rates in 5 and 60 ton liquid argon detectors at a variety of existing and hypothetical locations along the beamline are found to be comparable to the largest existing decay-at-rest datasets for some channels. The physics implications and experimental challenges of such a measurement are discussed, along with prospects for measurements at targeted facilities along a future Fermilab long-baseline neutrino beam.
↳ hep-exhep-phnucl-exphysics.ins-detPoS(2016)·14 citations
31*
Scalar 3-point functions in CFT: renormalisation, beta functions and anomalies
Adam Bzowski🇧🇪 · Paul McFadden🇬🇧 · Kostas Skenderis🇬🇧
We present a comprehensive discussion of renormalisation of 3-point functions of scalar operators in conformal field theories in general dimension. We have previously shown that conformal symmetry uniquely determines the momentum-space 3-point functions in terms of certain integrals involving a product of three Bessel functions (triple-K integrals). The triple-K integrals diverge when the dimensions of operators satisfy certain relations and we discuss how to obtain renormalised 3-point functions in all cases. There are three different types of divergences: ultralocal, semilocal and nonlocal, and a given divergent triple-K integral may have any combination of them. Ultralocal divergences may be removed using local counterterms and this results in new conformal anomalies. Semilocal divergences may be removed by renormalising the sources, and this results in CFT correlators that satisfy Callan-Symanzik equations with beta functions. In the case of non-local divergences, it is the triple-K representation that is singular, not the 3-point function. Here, the CFT correlator is the coefficient of the leading nonlocal singularity, which satisfies all the expected conformal Ward identities. Such correlators exhibit enhanced symmetry: they are also invariant under dual conformal transformations where the momenta play the role of coordinates. When both anomalies and beta functions are present the correlators exhibit novel analytic structure containing products of logarithms of momenta. We illustrate our discussion with numerous examples, including free field realisations and AdS/CFT computations.
↳ hep-thhep-phJHEP(2016)·202 citations
32*
From Stringy Particle Physics to Moduli Stabilisation and Cosmology
Gabriele Honecker🇩🇪
Intersecting D6-branes provide a geometrically intuitive road to stringy particle physics models, where D6-branes stuck at orbifold singularities can lead to the stabilisation of deformation moduli, and the QCD axion can arise from the open string sector in a very constrained way compared to pure field theory. We demonstrate this interplay of different physical features here through an explicit model.
↳ hep-thhep-phFortsch.Phys.(2016)·4 citations
33*
Proposal for the Quantum Simulation of the CP(2) Model on Optical Lattices
Catherine Laflamme🇦🇹 · Wynne Evans🇨🇭 · Marcello Dalmonte🇦🇹 · Urs Gerber🇲🇽 · Héctor Mejía-Díaz🇲🇽 · Wolfgang Bietenholz🇲🇽 · Uwe-Jens Wiese🇨🇭 · Peter Zoller🇦🇹
The 2d CP(N-1) models share a number of features with QCD, like asymptotic freedom, a dynamically generated mass gap and topological sectors. They have been formulated and analysed successfully in the framework of the so-called D-theory, which provides a smooth access to the continuum limit. In that framework, we propose an experimental set-up for the quantum simulation of the CP(2) model. It is based on ultra-cold Alkaline-Earth Atoms (AEAs) located on the sites of an optical lattice, where the nuclear spins represent the relevant degrees of freedom. We present numerical results for the correlation length and for the real time decay of a false vacuum, to be compared with such a future experiment. The latter could also enable the exploration of theta-vacua and of the phase diagram at finite chemical potentials, since it does not suffer from any sign problem.
↳ hep-lathep-phquant-phPoS(2016)·6 citations
34*
Preheating after Multifield Inflation with Nonminimal Couplings, I: Covariant Formalism and Attractor Behavior
Matthew P. DeCross🇺🇸 · David I. Kaiser🇺🇸 · Anirudh Prabhu🇺🇸 · Chanda Prescod-Weinstein🇺🇸 · Evangelos I. Sfakianakis🇺🇸
This is the first of a three-part series of papers, in which we study the preheating phase for multifield models of inflation involving nonminimal couplings. In this paper, we study the single-field attractor behavior that these models exhibit during inflation and quantify its strength and parameter dependence. We further demonstrate that the strong single-field attractor behavior persists after the end of inflation. Preheating in such models therefore generically avoids the "de-phasing" that typically affects multifield models with minimally coupled fields, allowing efficient transfer of energy from the oscillating inflaton condensate(s) to coupled perturbations across large portions of parameter space. We develop a doubly-covariant formalism for studying the preheating phase in such models and identify several features specific to multifield models with nonminimal couplings, including effects that arise from the nontrivial field-space manifold. In papers II and III, we apply this formalism to study how the amplification of adiabatic and isocurvature perturbations varies with parameters, highlighting several distinct regimes depending on the magnitude of the nonminimal couplings $ξ_{I}$ .
↳ astro-ph.COhep-phhep-thPRD(2018)·131 citations
35*
Lattice study of the Higgs-Yukawa model in and beyond the Standard Model
David Y.-J. Chu🇹🇼 · Karl Jansen🇩🇪 · Bastian Knippschild🇩🇪 · C.-J. David Lin🇹🇼 · Kei-Ichi Nagai🇯🇵 · Attila Nagy🇩🇪
We derive finite-size scaling formulae for four-dimensional Higgs-Yukawa models near the Gaussian fixed point. These formulae will play an essential role in future, detailed investigation of such models. In particular, they can be used to determine the nature of the observed phase transitions, and confirm or rule out the possibility of having non-trivial fixed points in the Higgs-Yukawa models. Our scaling formula for Binder's cumulant is tested against lattice simulations carried out at weak couplings, and good agreement is found. As a separate project, we also present preliminary results from our study of a chirally-invariant Higgs-Yukawa model including a dimension-six operator at finite temperature. Our work provides first indications of first-order temperature-induced phase transitions near the infinite cutoff limit in this model.
↳ hep-lathep-phPoS(2016)·3 citations
36*
Photon self-interaction on deformed spacetime
Raul Horvat🇭🇷 · Josip Trampetić🇩🇪 · Jiangyang You🇭🇷
A novel nonlocal four-photon interaction on the deformed spacetime is derived and studied in the three selected models (I, II, III). The first two models (I, II) are obtained via two distinct second-order $θ$ -exact Seiberg-Witten maps of the noncommutative U(1) gauge field strength on Moyal space. The third one (III), inspired by the manifestly gauge invariant structures emerging in the first two, due to the model generality has been constructed with a different set of freedom parameters. The physical relevancy of all models is analyzed by evaluating the four-photon-tadpole diagram, which, when combined with the bubble graph, enables us to fully consider all contributions to the one-loop photon polarization tensor. For an arbitrary noncommutative matrix theta^\mu\nu, the full quadratic IR divergence cancellation in the one-loop photon two-point function is obtained with particular combinations of Seiberg-Witten map/gauge-symmetry freedom parameters in models I and II. Finally, our model III enables complete elimination of all pathological terms in the photon polarization tensor at one-loop order if a special value for the theta matrix is chosen.
↳ hep-thhep-phmath-phmath.MPPRD(2015)·13 citations
37*
Gravitating BPS Skyrmions
Sven Bjarke Gudnason🇨🇳 · Muneto Nitta🇯🇵 · Nobuyuki Sawado🇯🇵
The BPS Skyrme model has many exact analytic solutions in flat space. We generalize the model to a curved space or spacetime and find that the solutions can only be BPS for a constant time-time component of the metric tensor. We find exact solutions on the curved spaces: a 3-sphere and a 3-hyperboloid; and we further find an analytic gravitating Skyrmion on the 3-sphere. For the case of a nontrivial time-time component of the metric, we suggest a potential for which we find analytic solutions on anti-de Sitter and de Sitter spacetimes in the limit of no gravitational backreaction. We take the gravitational coupling into account in numerical solutions and show that they are well approximated by the analytic solutions for weak gravitational coupling.
↳ hep-thhep-phnlin.SIJHEP(2015)·19 citations
38*
The two-field regime of natural inflation
Ana Achúcarro🇳🇱 · Vicente Atal🇳🇱 · Masahiro Kawasaki🇯🇵 · Fuminobu Takahashi🇯🇵
The simplest two-field completion of natural inflation has a regime in which both fields are active and in which its predictions are within the Planck 1- $σ$ confidence contour. We show this for the original model of natural inflation, in which inflation is achieved through the explicit breaking of a U(1) symmetry. We consider the case in which the mass coming from explicit breaking of this symmetry is comparable to that from spontaneous breaking, which we show is consistent with a hierarchy between the corresponding energy scales. While both masses are comparable when the observable modes left the horizon, the mass hierarchy is restored in the last e-foldings of inflation, rendering the predictions consistent with the isocurvature bounds. For completeness, we also study the predictions for the case in which there is a large hierarchy of masses and an initial period of inflation driven by the (heavy) radial field.
↳ astro-ph.COhep-phhep-thJCAP(2015)·12 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.