HEP Phenomenology·hep-ph

Tue·Nov 14, 2017Tuesday·November 14, 2017

40 papers—35 primary·5 cross-listed·reconstructed*

01*
Heavy-Lifting of Gauge Theories By Cosmic Inflation
Soubhik Kumar🇺🇸 · Raman Sundrum🇺🇸
Future measurements of primordial non-Gaussianity can reveal cosmologically produced particles with masses of order the inflationary Hubble scale and their interactions with the inflaton, giving us crucial insights into the structure of fundamental physics at extremely high energies. We study gauge-Higgs theories that may be accessible in this regime, carefully imposing the constraints of gauge symmetry and its (partial) Higgsing. We distinguish two types of Higgs mechanisms: (i) a standard one in which the Higgs scale is constant before and after inflation, where the particles observable in non-Gaussianities are far heavier than can be accessed by laboratory experiments, perhaps associated with gauge unification, and (ii) a "heavy-lifting" mechanism in which couplings to curvature can result in Higgs scales of order the Hubble scale during inflation while reducing to far lower scales in the current era, where they may now be accessible to collider and other laboratory experiments. In the heavy-lifting option, renormalization-group running of terrestrial measurements yield predictions for cosmological non-Gaussianities. If the heavy-lifted gauge theory suffers a hierarchy problem, such as does the Standard Model, confirming such predictions would demonstrate a striking violation of the Naturalness Principle. While observing gauge-Higgs sectors in non-Gaussianities will be challenging given the constraints of cosmic variance, we show that it may be possible with reasonable precision given favorable couplings to the inflationary dynamics.
hep-phastro-ph.COgr-qcJHEP(2018)·131 citations
02*
The analytical $O (a_{s}^{4})$ expression for the polarized Bjorken sum rule in the miniMOM scheme and the consequences for the generalized Crewther relation
A.L.Kataev🇷🇺 · V.S.Molokoedov🇷🇺
The analytical $O (a_{s}^{4})$ perturbative QCD expression for the flavour non-singlet contribution to the Bjorken polarized sum rule in the rather applicable at present gauge--dependent $miniMOM$ scheme is obtained. For the considered three values of the gauge parameter, namely $ξ = 0$ (Landau gauge), $ξ = - 1$ (anti--Feynman gauge) and $ξ = - 3$ (Stefanis--Mikhailov gauge), the scheme-dependent coefficients are considerably smaller than the gauge-independent $MS$ results. It is found that the fundamental property of the factorization of the QCD renormalization group $β$ -function in the generalized Crewther relation, which is valid in the gauge-invariant $MS$ scheme up to $O (a_{s}^{4})$ -level at least, is unexpectedly valid at the same level in the $miniMOM$ -scheme for $ξ = 0$ , and for $ξ = - 1$ and $ξ = - 3$ in part.
hep-phhep-lathep-thJ.Phys.Conf.Ser.(2017)·8 citations
03*
Are PDFs still consistent with Tevatron data?
Zack Sullivan🇺🇸
As active data taking has moved to the LHC at CERN, more and more LHC data have been included into fits of parton distribution functions. An anomaly has arisen where formerly excellent agreement between theoretical predictions and experiment in single-top-quark production at the Tevatron is no longer quite as good. Is this indicative of a deeper issue?
hep-phEPJ Web Conf.(2018)·5 citations
04*
Probing 6D Operators at Future $e^{-} e^{+}$ Colliders
Wen Han Chiu🇨🇳 · Sze Ching Leung🇨🇳 · Tao Liu🇨🇳 · Kun-Feng Lyu🇨🇳 · Lian-Tao Wang🇺🇸
We explore the sensitivities at future $e^{-} e^{+}$ colliders to probe a set of six-dimensional operators which can modify the SM predictions on Higgs physics and electroweak precision measurements. We consider the case in which the operators are turned on simultaneously. Such an analysis yields a "conservative" interpretation on the collider sensitivities, complementary to the "optimistic" scenario where the operators are individually probed. After a detail analysis at CEPC in both "conservative" and "optimistic" scenarios, we also considered the sensitivities for FCC-ee and ILC. As an illustration of the potential of constraining new physics models, we applied sensitivity analysis to two benchmarks: holographic composite Higgs model and littlest Higgs model.
hep-phJHEP(2018)·28 citations
05*
The CP-Violating 2HDM in Light of a Strong First Order Electroweak Phase Transition and Implications for Higgs Pair Production
Philipp Basler🇩🇪 · Margarete Mühlleitner🇩🇪 · Jonas Wittbrodt🇩🇪
We investigate the strength of the electroweak phase transition (EWPT) within the CP-violating 2-Higgs-Doublet Model (C2HDM). By applying a renormalisation scheme which allows efficient scans of the C2HDM parameter space, we analyse the possibility of a strong first order EWPT required for baryogenesis and study its phenomenological implications for the LHC. Like in the CP-conserving (real) 2HDM (R2HDM) we find that a strong EWPT favours mass gaps between the non-SM-like Higgs bosons. These lead to prominent final states comprised of gauge+Higgs bosons or pairs of Higgs bosons. In contrast to the R2HDM, the CP-mixing of the C2HDM also favours approximately mass degenerate spectra with dominant decays into SM particles. The requirement of a strong EWPT further allows us to distinguish the C2HDM from the R2HDM using the signal strengths of the SM-like Higgs boson. We additionally find that a strong EWPT requires an enhancement of the SM-like trilinear Higgs coupling at next-to-leading order (NLO) by up to a factor of 2.4 compared to the NLO SM coupling, establishing another link between cosmology and collider phenomenology. We provide several C2HDM benchmark scenarios compatible with a strong EWPT and all experimental and theoretical constraints. We include the dominant branching ratios of the non-SM-like Higgs bosons as well as the Higgs pair production cross section of the SM-like Higgs boson for every benchmark point. The pair production cross sections can be substantially enhanced compared to the SM and could be observable at the high-luminosity LHC, allowing access to the trilinear Higgs couplings.
hep-phJHEP(2018)·133 citations
06*
The W and Z boson spin observables as messengers of new physics at LHC
J. Bernabeu🇪🇸 · A. Segarra🇪🇸
The successful LHC operation suggests going beyond the search of excess of events for the quest of new physics. We demonstrate that the eight multipole parameters describing the spin state of the W or Z bosons are able to disentangle their hidden production mechanism. They can be separately extracted from well defined angular asymmetries in the leptonic distribution of boson decays. The discriminating power of this analysis is well illustrated by: (i) polarised top quark decays, (ii) two body decay of heavy resonances, (iii) Drell-Yan production of Z plus jets, (iv) Z boson plus missing transverse energy.
hep-phPoS(2018)·0 citations
07*
Stimulated X-rays in resonant atom Majorana mixing
A. Segarra🇪🇸 · J. Bernabeu🇪🇸
Massive neutrinos demand to ask whether they are Dirac or Majorana particles. Majorana neutrinos are an irrefutable proof of physics beyond the Standard Model. Neutrinoless double electron capture is not a process but a virtual $Δ L = 2$ mixing between a parent $^{A} Z$ atom and a daughter $^{A} (Z - 2)$ excited atom with two electron holes. As a mixing between two neutral atoms and the observable signal in terms of emitted two-hole X-rays, the strategy, experimental signature and background are different from neutrinoless double beta decay. The mixing is resonantly enhanced for almost degeneracy and, under these conditions, there is no irreducible background from the standard two-neutrino channel. We reconstruct the natural time history of a nominally stable parent atom since its production either by nature or in the laboratory. After the time periods of atom oscillations and the decay of the short-lived daughter atom, at observable times the relevant "stationary" states are the mixed metastable long-lived state and the short-lived excited state, as well as the ground state of the daughter atom. Their natural population inversion is most appropriate for exploiting the bosonic nature of the observed X-rays by means of stimulating X-ray beams. Among different observables of the atom Majorana mixing, we include the enhanced rate of stimulated X-ray emission from the long-lived metastable state by a high-intensity X-ray beam. A gain factor of 100 can be envisaged in a facility like European XFEL.
hep-phJ.Phys.Conf.Ser.(2020)·0 citations
08*
Color superconductivity from the chiral quark-meson model
Armen Sedrakian🇩🇪 · Ralf-Arno Tripolt🇮🇹 · Jochen Wambach🇮🇹
We study the two-flavor color superconductivity of low-temperature quark matter in the vicinity of chiral phase transition in the quark-meson model where the interactions between quarks are generated by pion and sigma exchanges. Starting from the Nambu-Gor'kov propagator in real-time formulation we obtain finite temperature (real axis) Eliashberg-type equations for the quark self-energies (gap functions) in terms of the in-medium spectral function of mesons. Exact numerical solutions of the coupled nonlinear integral equations for the real and imaginary parts of the gap function are obtained in the zero temperature limit using a model input spectral function. We find that these components of the gap display a complicated structure with the real part being strongly suppressed above $2 Δ_{0}$ , where $Δ_{0}$ is its on-shell value. We find $Δ_{0} ≃ 40$ MeV close to the chiral phase transition.
hep-phastro-ph.HEhep-thnucl-thPLB(2018)·8 citations
09*
On the mass and decay constant of the P-wave ground and radially excited $h_{c}$ and $h_{b}$ axial-vector mesons
K. Azizi🇹🇷 · J. Y. Sungu🇹🇷
The mass and decay constant of the heavy quarkonia $h_{Q} (1 P)$ and $h_{Q} (2 P)$ (Q = b, c) with quantum numbers $J^{P C} = 1^{+-}$ are calculated in the framework of the two-point QCD sum rule method by taking into account the vacuum condensates up to eight dimensions. We compare our results for parameters of the $h_{b} (1 P)$ and $h_{c} (1 P)$ quarkonia, and their first radially excited states $h_{b} (2 P)$ and $h_{c} (2 P)$ with available experimental data as well as predictions of other theoretical studies existing in the literature. The results of present work may shed light on experimental searches for the $h_{c} (2 P)$ state.
hep-phhep-exhep-latJ.Phys.G(2019)·13 citations
10*
Spin-flavor oscillations of ultrahigh-energy cosmic neutrinos in interstellar space: The role of neutrino magnetic moments
Podist Kurashvili🇵🇱 · Konstantin A. Kouzakov🇷🇺 · Levan Chotorlishvili🇩🇪 · Alexander I. Studenikin🇷🇺
A theoretical analysis of possible influence of neutrino magnetic moments on the propagation of ultrahigh-energy cosmic neutrinos in the interstellar space is carried out under the assumption of two-neutrino mixing. The exact solution of the effective equation for neutrino evolution in the presence of a magnetic field and matter is obtained, which accounts for four neutrino species corresponding to two different flavor states with positive and negative helicities. Using most stringent astrophysical bounds on the putative neutrino magnetic moment, probabilities of neutrino flavor and spin oscillations are calculated on the basis of the obtained exact solution. Specific patterns of spin-flavor oscillations are determined for neutrino-energy values characteristic of, respectively, the cosmogenic neutrinos, the Greisen-Zatsepin-Kuz'min (GZK) cutoff, and well above the cutoff.
hep-phastro-ph.HEhep-exPRD(2017)·44 citations
11*
Weak dipole moments of the tau lepton in models with an extended scalar sector
M. A. Arroyo-Ureña🇲🇽 · G. Hernández-Tomé🇲🇽 · G. Tavares-Velasco🇲🇽
We consider renormalizable couplings of neutral $ϕ$ , singly $ϕ^{\pm}$ , and doubly charged $ϕ^{\pm\pm}$ scalar bosons to leptons and the $Z$ gauge boson and calculate the one-loop contributions to the anomalous weak magnetic dipole moment (AWMDM) $a_{τ}^{W}$ and the weak electric dipole moment (WEDM) $d_{τ}^{W}$ of a charged lepton in a model independent way. The analytic expressions are presented in terms of both parametric integrals and Passarino-Veltman scalar functions. Among the new contributions, there are those arising from the vertices of the type $ϕ^{\pm} W^{\mp} Z$ and $Z ϕ_{i} ϕ_{j}$ ( $i \neq = j$ ), along with contributions from doubly charged scalar bosons. Both $a_{τ}$ and $d_{τ}^{W}$ are evaluated in several scenarios , first in a model independent way and then within some popular models, such as two-Higgs doublet models (THDMs), multiple-Higgs doublet models and Higgs triplet models. As far as $a_{τ}^{W}$ is concerned, its real part reaches values as high as $1 0^{- 10} - 1 0^{- 9}$ for masses of the new scalar bosons in the 200 GeV range, whereas the imaginary part is one or two orders of magnitude below. On the other hand, the most promising scenario for a nonvanishing WEDM is offered by a $C P$ -violating THDM in a scenario where the heavy neutral scalar bosons are a mixture of $C P$ eigenstates. It is found that the real part of $d_{τ}^{W}$ is of the order of $1 0^{- 24}$ ecm and its imaginary part can reach the $1 0^{- 26}$ ecm level for masses of the new scalar bosons of the order of a few hundred of GeVs. Both the tau AWMDM and WEDM decrease dramatically as the scalar boson masses increase.
hep-phPRD(2018)·8 citations
12*
Detecting Fluorescent Dark Matter with X-ray lasers
Francesca Day🇬🇧 · Malcolm Fairbairn🇬🇧
Fluorescent Dark Matter has been suggested as a possible explanation of both the 3.5 keV excess in the diffuse emission of the Perseus Cluster and of the deficit at the same energy in the central active galaxy within that cluster, NGC 1275. In this work we point out that such a dark matter candidate can be searched for at the new X-ray laser facilities that are currently being built and starting to operate around the world. We present one possible experimental set up where the laser is passed through a narrow cylinder lined with lead shielding. Flourescent Dark Matter would be excited upon interaction with the laser photons and travel across the lead shielding to decay outside the cylinder, in a region which has been instrumented with X-ray detectors. For an instrumented length of 7cm at the LCLS-II laser we expect $O (1 - 10)$ such events per week for parameters which explain the astronomical observations.
hep-phEPJC(2018)·2 citations
13*
Trident pair production in plane waves: Coherence, exchange, and spacetime inhomogeneity
Victor Dinu🇷🇴 · Greger Torgrimsson🇩🇪
We study the trident process in inhomogeneous plane wave background fields. We obtain compact analytical expressions for all terms in the probability, including the exchange part, for an arbitrarily shaped plane wave. We evaluate the probability numerically using complex deformation of lightfront time integrals and derive various analytical approximations. Our results provide insights into the importance of the one-step and exchange parts of the probability relative to the two-step process, and into the convergence to the locally constant field approximation.
hep-phhep-thPRD(2018)·74 citations
14*
Gauge invariance and kaon production in deep inelastic scattering at low scales
Juan V. Guerrero🇺🇸 · Alberto Accardi🇺🇸
This paper focuses on hadron mass effects in calculations of semi-inclusive kaon production in lepton-Deuteron deeply inelastic scattering at HERMES and COMPASS kinematics. In the collinear factorization framework, the corresponding cross section is shown to factorize, at leading order and leading twist, into products of parton distributions and fragmentation functions evaluated in terms of kaon- and nucleon-mass-dependent scaling variables, and to respect gauge invariance. It is found that hadron mass corrections for integrated kaon multiplicities sizeably reduce the apparent large discrepancy between measurements of $K^{+} + K^{-}$ multiplicities performed by the two collaborations, and fully reconcile their $K^{+} / K^{-}$ ratios.
hep-phhep-exPRD(2018)·20 citations
15*
Dark matter in the Georgi-Machacek model with an additional inert doublet
Terry Pilkington🇨🇦
We study a model that extends the Georgi-Machacek model by the addition of an inert doublet, $Φ_{2}$ . This allows for the model to contain a natural dark matter candidate, $H^{0}$ . For a number of benchmark points at two DM candidate masses ( $m_{H^{0}} \in {70, 250}$ GeV), we determine the relic abundance, direct detection cross section, and collider constraints. We find that the collider studies used do not constrain the model. For the parameter region chosen, the points are ruled out by direct detection experimental results. At the lower mass point, we do not find a viable parameter point, while at the higher mass we do find an additional point that satisfies all the applied constraints.
hep-ph7 citations
16*
Light Higgsino and Gluino in $R$ -invariant Direct Gauge Mediation
Norimi Yokozaki🇯🇵 · Ryo Nagai🇯🇵
We provide a simple solution to the $μ$ - $B_{μ}$ problem in the " $R$ -invariant direct gauge mediation model". With the solution, the Higgsino and gluino are predicted to be light as $O (100)$ GeV and $O (1)$ TeV, respectively. Those gluino and Higgsino can be accessible at the LHC and future collider experiments. Moreover, dangerous dimension five operators inducing rapid proton decays are naturally suppressed by the $R$ -symmetry.
hep-phPLB(2018)·1 citation
17*
Perturbative Expansions in QCD Improved by Conformal Mappings of the Borel Plane
Irinel Caprini🇷🇴 · Jan Fischer🇨🇿 · Gauhar Abbas🇮🇳 · B. Ananthanarayan🇮🇳
Perturbation expansions appear to be divergent series in many physically interesting situations, including in quantum field theories like quantum electrodynamics (QED) and quantum chromodynamics (QCD), where the perturbative coefficients exhibit a factorial growth at large orders. While this feature has little impact on physical predictions in QED, it can have nontrivial consequences in applications of perturbative QCD at moderate energies. In particular, it affects the theoretical error in the extraction of the strong coupling $α_{s}$ from hadronic $τ$ decays, despite progress of perturbative calculations available at present to four loops. We discuss a new type of perturbative expansion for QCD correlators, which uses instead of the standard powers of the coupling a new set of expansion functions. These functions are defined by means of an optimal conformal mapping of the Borel complex plane, which implements the known features of the high-order divergence in terms of the lowest Borel-plane singularities. The properties of the expansion functions resemble those of the expanded correlators, by exhibiting in particular the singular behaviour of the correlators at $α_{s} = 0$ . We prove the good convergence properties of the new expansions on mathematical models that simulate the physical polarization function for light quarks and its derivative (the Adler function), in various prescriptions of renormalization-group summation.
hep-phPerturbation Theory: Advances in Research…·18 citations
18*
Inclusive heavy quark photoproduction in $pp$ , $pP b$ and $P b P b$ collisions at Run 2 LHC energies
V. P. Goncalves🇧🇷 · G. Sampaio dos Santos🇧🇷 · C. R. Sena🇧🇷
In this paper we present a comprehensive analysis of the inclusive heavy quark photoproduction in $pp$ , $pP b$ and $P b P b$ collisions at Run 2 LHC energies using the Color Dipole formalism. The rapidity distributions and total cross sections for the charm and bottom production are estimated considering the more recent phenomenological models for the dipole - proton scattering amplitude, which are based on the Color Glass Condensate formalism and are able to describe the inclusive and exclusive $e p$ HERA data. Moreover, we present, by the first time, the predictions for the transverse momentum distributions of the $D$ and $B$ mesons produced in the photon -- induced interactions.
hep-phhep-exnucl-exnucl-thNPA(2018)·20 citations
19*
Heavy quarkonium suppression in a fireball
Nora Brambilla🇩🇪 · Miguel A. Escobedo🇫🇮 · Joan Soto🇪🇸 · Antonio Vairo🇩🇪
We perform a comprehensive study of the time evolution of heavy-quarkonium states in an expanding hot QCD medium by implementing effective field theory techniques in the framework of open quantum systems. The formalism incorporates quarkonium production and its subsequent evolution in the fireball including quarkonium dissociation and recombination. We consider a fireball with a local temperature that is much smaller than the inverse size of the quarkonium and much larger than its binding energy. The calculation is performed at an accuracy that is leading-order in the heavy-quark density expansion and next-to-leading order in the multipole expansion. Within this accuracy, for a smooth variation of the temperature and large times, the evolution equation can be written as a Lindblad equation. We solve the Lindblad equation numerically both for a weakly-coupled quark-gluon plasma and a strongly-coupled medium. As an application, we compute the nuclear modification factor for the $Υ (1 S)$ and $Υ (2 S)$ states. We also consider the case of static quarks, which can be solved analytically. Our study fulfils three essential conditions: it conserves the total number of heavy quarks, it accounts for the non-Abelian nature of QCD and it avoids classical approximations.
hep-phhep-lathep-thnucl-thPRD(2018)·186 citations
20*
ALPs EFT & Collider Signatures
R. del Rey🇪🇸
We explore the leading effective interactions between the Standard Model and a generic singlet CP-odd (pseudo)Goldstone boson in two frameworks for electroweak symmetry breaking: linear and non-linear realizations, determining the basis of leading effective operators for the latter. New bounds are obtained and prospects of signals at colliders are explored. Mono-Z, mono-W, and aW{\gamma} are signals expected in both frameworks while non-standard Higgs decays and mono-h signals may point to non-linear EWSB realizations.
hep-ph1 citation
21*
Simulations of Cold Electroweak Baryogenesis: Quench from portal coupling to new singlet field
Zong-Gang Mou🇳🇴 · Paul M. Saffin🇬🇧 · Anders Tranberg🇳🇴
We compute the baryon asymmetry generated from Cold Electroweak Baryogenesis, when a dynamical Beyond-the-Standard-Model scalar singlet field triggers the spinodal transition. Using a simple potential for this additional field, we match the speed of the quench to earlier simulations with a "by-hand" mass flip. We find that for the parameter subspace most similar to a by-hand transition, the final baryon asymmetry shows a similar dependence on quench time and is of the same magnitude. For more general parameter choices the Higgs-singlet dynamics can be very complicated, resulting in an enhancement of the final baryon asymmetry. Our results validate and generalise results of simulations in the literature and open up the Cold Electroweak Baryogenesis scenario to further model building.
hep-phhep-lathep-thJHEP(2018)·7 citations
22*
Signatures of Dark Radiation in Neutrino and Dark Matter Detectors
Yanou Cui🇺🇸 · Maxim Pospelov🇨🇦 · Josef Pradler🇦🇹
We consider the generic possibility that the Universe's energy budget includes some form of relativistic or semi-relativistic dark radiation (DR) with non-gravitational interactions with Standard Model (SM) particles. Such dark radiation may consist of SM singlets or a non-thermal, energetic component of neutrinos. If such DR is created at a relatively recent epoch, it can carry sufficient energy to leave a detectable imprint in experiments designed to search for very weakly interacting particles: dark matter and underground neutrino experiments. We analyze this possibility in some generality, assuming that the interactive dark radiation is sourced by late decays of an unstable particle, potentially a component of dark matter, and considering a variety of possible interactions between the dark radiation and SM particles. Concentrating on the sub-GeV energy region, we derive constraints on different forms of DR using the results of the most sensitive neutrino and dark matter direct detection experiments. In particular, for interacting dark radiation carrying a typical momentum of $\sim 30$ ~MeV $/ c$ , both types of experiments provide competitive constraints. This study also demonstrates that non-standard sources of neutrino emission (e.g. via dark matter decay) are capable of creating a "neutrino floor" for dark matter direct detection that is closer to current bounds than is expected from standard neutrino sources.
hep-phastro-ph.COhep-exPRD(2018)·62 citations
23*
Millicharged Scalar Fields, Massive Photons and the Breaking of $S U (3)_{C} \times U (1)_{EM}$
Jennifer Rittenhouse West🇺🇸
Under the assumption that the current epoch of the Universe is not special, i.e. is not the final state of a long history of processes in particle physics, the cosmological fate of $S U (3)_{C} \times U (1)_{EM}$ is investigated. Spontaneous symmetry breaking of $U (1)_{EM}$ at the temperature of the Universe today is carried out. The charged scalar field $ϕ_{EM}$ which breaks the symmetry is found to be ruled out for the charge of the electron, $q = e$ . Scalar fields with millicharges are viable and limits on their masses and charges are found to be $q ≲ 1 0^{- 3} e$ and $m_{ϕ_{EM}} ≲ 1 0^{- 5} eV$ . Furthermore, it is possible that $U (1)_{EM}$ has already been broken at temperatures higher than $T = 2.7 K$ given the nonzero limits on the mass of the photon. A photon mass of $m_{γ} = 1 0^{- 18} eV$ , the current upper limit, is found to require a spontaneously symmetry breaking scalar mass of $m_{ϕ_{EM}} \sim 1 0^{- 13} eV$ with charge $q = 1 0^{- 6} e$ , well within the allowed parameter space of the model. Finally, the cosmological fate of the strong interaction is studied. $S U (3)_{C}$ is tested for complementarity in which the confinement phase of QCD $+$ colored scalars is equivalent to a spontaneously broken $S U (3)$ gauge theory. If complementarity is not applicable, $S U (3)_{C}$ has multiple symmetry breaking paths with various final symmetry structures. The stability of the colored vacuum at finite temperature in this scenario is nonperturbative and a definitive statement on the fate of $S U (3)_{C}$ is left open. Cosmological implications for the metastability of the vacua - electromagnetic, color and electroweak - are discussed.
hep-phhep-thPRD(2019)·6 citations
24*
Constraining anomalous gauge boson couplings in $e^{+} e^{-} \to W^{+} W^{-}$ using polarization asymmetries with polarized beams
Rafiqul Rahaman🇮🇳 · Ritesh K. Singh🇮🇳
We study the anomalous $W^{+} W^{-} V$ ( $V = γ, Z$ ) couplings in $e^{+} e^{-} \to W^{+} W^{-}$ using the complete set of polarization observables of $W$ boson with longitudinally polarized beams. We use most general Lorentz invariant form factors parametrization as well as $S U (2) \times U (1)$ invariant dimension $6$ effective operators for the effective $W^{+} W^{-} V$ couplings. We estimate simultaneous limits on the anomalous couplings in both the parametrizations using cross section, forward backward asymmetry and polarization observables of $W$ boson with different kinematical cuts using Markov-Chain--Monte-Carlo (MCMC) method for an $e^{+} e^{-}$ collider running at centre of mass energy of $s = 500$ GeV and $L = 100$ fb $^{- 1}$ . The best limits on form factors are obtained to be $1 \sim 5 \times 1 0^{- 2}$ for $e^{-}$ and $e^{+}$ polarization being $(+ 0.4, - 0.4)$ . For operator's coefficients, the best limits are obtained to be $1 \sim 16$ TeV $^{- 2}$ .
hep-phhep-ex10 citations
25*
Structure of hadron resonances with a nearby zero of the amplitude
Yuki Kamiya🇯🇵 · Tetsuo Hyodo🇯🇵
We discuss the relation between the analytic structure of the scattering amplitude and the origin of an eigenstate represented by a pole of the amplitude.If the eigenstate is not dynamically generated by the interaction in the channel of interest, the residue of the pole vanishes in the zero coupling limit. Based on the topological nature of the phase of the scattering amplitude, we show that the pole must encounter with the Castillejo-Dalitz-Dyson (CDD) zero in this limit. It is concluded that the dynamical component of the eigenstate is small if a CDD zero exists near the eigenstate pole. We show that the line shape of the resonance is distorted from the Breit-Wigner form as an observable consequence of the nearby CDD zero. Finally, studying the positions of poles and CDD zeros of the KbarN-piSigma amplitude, we discuss the origin of the eigenstates in the Lambda(1405) region.
hep-phnucl-thPRD(2018)·11 citations
26*
TMD splitting functions in kT factorization: the real contribution to the gluon-to-gluon splitting
M. Hentschinski🇲🇽 · A. Kusina🇵🇱 · K. Kutak🇵🇱 · M. Serino🇵🇱
We calculate the transverse momentum dependent gluon-to-gluon splitting function within $k_{T}$ -factorization, generalizing the framework employed in the calculation of the quark splitting functions in [1-3] and demonstrate at the same time the consistency of the extended formalism with previous results. While existing versions of $k_{T}$ factorized evolution equations contain already a gluon-to-gluon splitting function i.e. the leading order Balitsky-Fadin-Kuraev-Lipatov (BFKL) kernel or the Ciafaloni-Catani-Fiore-Marchesini (CCFM) kernel, the obtained splitting function has the important property that it reduces both to the leading order BFKL kernel in the high energy limit, to the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) gluon-to-gluon splitting function in the collinear limit as well as to the CCFM kernel in the soft limit. At the same time we demonstrate that this splitting kernel can be obtained from a direct calculation of the QCD Feynman diagrams, based on a combined implementation of the Curci-Furmanski-Petronzio formalism for the calculation of the collinear splitting functions and the framework of high energy factorization.
hep-phEPJC(2018)·38 citations
27*
Wigner Distributions Using Light-Front Wave Functions
Asmita Mukherjee🇮🇳
We report on some recent advances in calculating the Wigner distributions for quarks and gluons, using overlaps of light-front wave functions.
hep-phPoS(2017)·0 citations
28*
Triangle singularity enhancing isospin violation in $B ˉ_{s}^{0} \to J / ψ π^{0} f_{0} (980)$
Wei-Hong Liang🇨🇳 · S. Sakai🇪🇸 · Ju-Jun Xie🇨🇳 · E. Oset🇪🇸
We perform calculations for the $B ˉ_{s}^{0} \to J / ψ π^{0} f_{0} (980)$ and $B ˉ_{s}^{0} \to J / ψ π^{0} a_{0} (980)$ reactions, showing that the first one is isospin-suppressed while the second one is isospin-allowed. The reaction proceeds via a triangle mechanism, with $B ˉ_{s}^{0} \to J / ψ K^{*} K ˉ + c . c .$ , followed by the decay $K^{*} \to K π$ and a further fusion of $K K ˉ$ into the $f_{0} (980)$ or $a_{0} (980)$ . We show that the mechanism develops a singularity around the $π^{0} f_{0} (980)$ or $π^{0} a_{0} (980)$ invariant mass of 1420 MeV where the $π^{0} f_{0}$ and $π^{0} a_{0}$ decay modes are magnified and also the ratio of $π^{0} f_{0}$ to $π^{0} a_{0}$ production. Using experimental information for the $B ˉ_{s}^{0} \to J / ψ K^{*} K ˉ + c . c .$ decay, we are able to obtain absolute values for the reactions studied which fall into the experimentally accessible range. The reactions proposed and the observables evaluated, when contrasted with actual experiments should be very valuable to obtain information on the nature of the low lying scalar mesons.
hep-phhep-exCPC(2018)·30 citations
29*
Exclusive neutrino-production of a charmed vector meson and transversity gluon GPDs
B. Pire🇫🇷 · L. Szymanowski🇵🇱
We calculate at the leading order in $α_{s}$ the QCD amplitude for exclusive neutrino production of a $D^{*}$ or $D_{s}^{*}$ charmed vector meson on a nucleon. We work in the framework of the collinear QCD approach where generalized parton distributions (GPDs) factorize from perturbatively calculable coefficient functions. We include $O (m_{c})$ terms in the coefficient functions and $O (m_{D})$ term in the definition of heavy meson distribution amplitudes. The show that the analysis of the angular distribution of the decay $D_{(s)}^{*} \to D_{(s)} π$ allows to access the transversity gluon GPDs.
hep-phhep-exnucl-exnucl-thPRD(2017)·22 citations
30*
LHC updated hadronic interaction packages analyzed up to cosmic-ray energies
L. Calcagni🇦🇷 · C. A. García Canal🇦🇷 · S. J. Sciutto🇦🇷 · T. Tarutina🇦🇷
The results of high energy simulated experiments where a given hadronic particle impacts on a given target are statistically analyzed. The energy range of the projectiles goes from below the LHC scale up to the highest cosmic ray energies. This study was carried out by using the pre- and post-LHC versions of the hadronic interaction models QGSJET, EPOS and SIBYLL. Our analysis indicates that the post-LHC models present smaller differences in various quantities that characterize the secondary particles produced after the hadronic collisions, in comparison with the corresponding differences that are found comparing the respective old (pre-LHC) versions of the hadronic models. However, it is also found that there exist some discrepancies among models that persist even at the LHC energy scale, that call for further theoretical investigation. An additional analysis of the impact that different modeling of hadronic collisions has on air shower development is also included. It consists of a detailed study of the impact of the different pre- and post-LHC versions of the hadronic models considered, for relevant observables like the muon production depth distribution.
hep-phPRD(2018)·10 citations
31*
Structures in the high-energy proton-proton diffraction cone
István Szanyi🇺🇦
The otherwise exponential high-energy proton-proton diffraction cone has two prominent structures, which are namely the "break" staying fixed around $t \approx - 0.1$ GeV $^{2}$ and the "dip" moving with increasing energy logarithmically towards smaller $∣ t ∣$ values. While at the ISR the two structures are separated by a distance of about $1$ GeV $^{2}$ , at the LHC the dip comes close to the periphery of the "break", thus affecting its parametrization. The Regge theory gives some opportunity to describe these phenomena which have still disputable and quite different physics.
hep-phhep-ex1 citation
32*
Multiple Couplings and Renormalization Scheme Ambiguities
D.G.C. McKeon🇨🇦 · Chenguang Zhao🇨🇦
The ambiguities inherent in renormalization are considered when using mass-independent renormalization in massless theories that involve two coupling coupling constants. We review how there is no renormalization scheme in which the beta-functions can be chosen to vanish beyond a certain order in perturbation theory, but that the beta-functions always contain ambiguities beyond first order. We examine how the coupling constants depend on the coefficients of the beta-function beyond one loop order. A way of characterizing renormalization schemes that doesn't use coefficients of the beta-function is considered for models with either one or two couplings. The renormalization scheme ambiguities of physical quantities computed to finite order in perturbation theory are also examined. We demonstrate how summation of the logarithms that have explicit dependence on the renormalization scale parameter mu in a physical quantity R leads to a cancellation with the implicit dependence of R on mu through the running couplings. It is also shown that there exists a renormalization scheme in which all radiative effects beyond lowest order are incorporated into the behaviour of the running couplings.
hep-phNPB(2018)·7 citations
33*
Concentrated Dark Matter: Enhanced Small-scale Structure from Co-Decaying Dark Matter
Jeff A. Dror🇺🇸 · Eric Kuflik🇮🇱 · Brandon Melcher🇺🇸 · Scott Watson🇺🇸
We study the cosmological consequences of co-decaying dark matter - a recently proposed mechanism for depleting the density of dark matter through the decay of nearly degenerate particles. A generic prediction of this framework is an early dark matter dominated phase in the history of the universe, that results in the enhanced growth of dark matter perturbations on small scales. We compute the duration of the early matter dominated phase and show that the perturbations are robust against washout from free-streaming. The enhanced small scale structure is expected to survive today in the form of compact micro-halos and can lead to significant boost factors for indirect detection experiments, such as FERMI, where dark matter would appear as point sources.
hep-phastro-ph.COhep-thPRD(2018)·67 citations
34*
Effective field theory approach to trans-TeV supersymmetry: covariant matching, Yukawa unification and Higgs couplings
James D. Wells🇺🇸 · Zhengkang Zhang🇺🇸
Dismissing traditional naturalness concerns while embracing the Higgs boson mass measurement and unification motivates careful analysis of trans-TeV supersymmetric theories. We take an effective field theory (EFT) approach, matching the Minimal Supersymmetric Standard Model (MSSM) onto the Standard Model (SM) EFT by integrating out heavy superpartners, and evolving MSSM and SMEFT parameters according to renormalization group equations in each regime. Our matching calculation is facilitated by the recent covariant diagrams formulation of functional matching techniques, with the full one-loop SUSY threshold corrections encoded in just 30 diagrams. Requiring consistent matching onto the SMEFT with its parameters (those in the Higgs potential in particular) measured at low energies, and in addition requiring unification of bottom and tau Yukawa couplings at the scale of gauge coupling unification, we detail the solution space of superpartner masses from the TeV scale to well above. We also provide detailed views of parameter space where Higgs coupling measurements have probing capability at future colliders beyond the reach of direct superpartner searches at the LHC.
hep-phJHEP(2018)·32 citations
35*
Chiral Tensor Particles in the Early Universe - Present Status
D. P. Kirilova🇧🇬 · V. M. Chizhov🇧🇬
In this work an update of the cosmological role and place of the chiral tensor particles in the Universe history is provided. We discuss an extended model with chiral tensor particles. The influence of these particles on the early Universe evolution is studied. Namely, the increase of the Universe expansion rate caused by the additional particles in this extended model is calculated, their characteristic interactions with the particles of the hot Universe plasma are studied and the corresponding times of their creation, scattering, annihilation and decay are estimated for accepted values of their masses and couplings, based on the recent experimental constraints. The period of abundant presence of these particles in the Universe evolution is determined.
hep-phastro-ph.COMod.Phys.Lett.A(2017)·8 citations
36*
Constraints on Born-Infeld gravity from the speed of gravitational waves after GW170817 and GRB 170817A
Soumya Jana🇮🇳 · Girish Kumar Chakravarty🇮🇳 · Subhendra Mohanty (PRL Ahmedabad, India)🇮🇳
The observations of gravitational waves from the binary neutron star merger event GW170817 and the subsequent observation of its electromagnetic counterparts from the gamma-ray burst GRB 170817A provide us a significant opportunity to study theories of gravity beyond general relativity. An important outcome of these observations is that they constrain the difference between the speed of gravity and the speed of light to less than $1 0^{- 15} c$ . Also, the time delay between the arrivals of gravitational waves at different detectors constrains the speed of gravity at the Earth to be in the range $0.55 c < v_{g w} < 1.42 c$ . We use these results to constrain a widely studied modified theory of gravity: Eddington-inspired Born-Infeld (EiBI) gravity. We show that, in EiBI theory, the speed of gravitational waves in matter deviates from $c$ . From the time delay in arrival of gravitational wave signals at Earth-based detectors, we obtain the bound on the theory parameter $κ$ as $∣ κ ∣ ≲ 1 0^{21} m^{2}$ . Similarly, from the time delay between the signals of GW170817 and GRB 170817A, in a background Friedmann-Robertson-Walker universe, we obtain $∣ κ ∣ ≲ 1 0^{37} m^{2}$ . Although the bounds on $κ$ are weak compared to other earlier bounds from the study of neutron stars, stellar evolution, primordial nucleosynthesis, etc., our bounds are from the direct observations and thus worth noting.
↳ gr-qcastro-ph.COhep-phPRD(2018)·62 citations
37*
Relating 't Hooft Anomalies of 4d Pure Yang-Mills and 2d $CP^{N - 1}$ Model
Masahito Yamazaki🇯🇵
It has recently been shown that a center-twisted compactification of the four-dimensional pure $S U (N)$ Yang-Mills theory on a three-torus gives rise to the two-dimensional $CP^{N - 1}$ -model on a circle with a flavor-twisted boundary condition. We verify the consistency of this statement non-perturbatively at theta angle $θ = π$ , in terms of the mixed 't Hooft anomalies for flavor symmetries and the time-reversal symmetry. This provides further support for the approach to the confinement of four-dimensional Yang-Mills theory from the two-dimensional $CP^{N - 1}$ -model.
↳ hep-thhep-lathep-phJHEP(2018)·40 citations
38*
Meson spectral function and screening masses in magnetized quark gluon plasma
Purnendu Chakraborty🇮🇳
We calculate the spectral function in pseudoscalar (scalar) channel in the high temperature phase of QCD in presence of a background magnetic field. Spatial and temporal screening masses are determined from the long distance behavior of the corresponding correlation functions.
↳ nucl-thhep-phEur.Phys.J.Plus(2019)·12 citations
39*
Symmetry breaking by bi-fundamentals
A.N. Schellekens🇪🇸
We derive all possible symmetry breaking patterns for all possible Higgs fields that can occur in intersecting brane models: bi-fundamentals and rank-2 tensors. This is a field-theoretic problem that was already partially solved in 1973 by Ling-Fong Li. In that paper the solution was given for rank-2 tensors of orthogonal and unitary group, and U(N x U(M) and O(N) x O(M) bi-fundamentals. We extend this first of al to symplectic groups. When formulated correctly, this turns out to be straightforward generalization of the previous results from real and complex numbers to quaternions. The extension to mixed bi-fundamentals is more challenging and interesting. The scalar potential has up to six real parameters. Its minima or saddle points are described by block-diagonal matrices built out of K blocks of size p x q. Here p=q=1 for the solutions of Ling-Fong Li, and the number of possibilities for p x q is equal to the number of real parameters in the potential, minus 1. The maximum block size is p x q=2 x 4. Different blocks cannot be combined, and the true minimum occurs for one choice of basic block, and for either K=1 or K maximal, depending on the parameter values.
↳ hep-thhep-phPRD(2018)·2 citations
40*
The Charm and Beauty of Strong Interactions
Bruno El-Bennich🇧🇷
We briefly review common features and overlapping issues in hadron and flavor physics focussing on continuum QCD approaches to heavy bound states, their mass spectrum and weak decay constants in different strong interaction models.
↳ nucl-thhep-exhep-phEPJ Web Conf.(2018)·4 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.