HEP Phenomenology·hep-ph
35 papers—29 primary·6 cross-listed·reconstructed*
S.V.Demidov🇷🇺 · D.S.Gorbunov🇷🇺
We point out that the diphoton excess at about 750 GeV recently discovered by the LHC experiments can be explained within supersymmetric models with low scale supersymmetry breaking with sgoldstino as a natural candidate. We discuss phenomenological consequences of this scenario describing possible signatures to test this hypothesis.
Shrihari Gopalakrishna🇮🇳 · Tuhin Subhra Mukherjee🇮🇳 · Soumya Sadhukhan🇮🇳
We study in detail the little-Higgs model proposed by Low, Skiba and Smith with an SU(6)/Sp(6) group structure. The effective theory at the TeV scale is a two-Higgs doublet model (2HDM) with additional heavy vector-like fermions and vector-bosons. We identify a set of independent input parameters and develop expressions for masses and couplings in terms of these. We perform a random scan of the parameter space and find points that satisfy constraints, including the recent 8 TeV LHC Higgs measurements, namely, the Higgs mass, Higgs couplings to the top, bottom, , and , top-quark mass, and collider bounds on colored vector-like fermions ( and ), and also precision electroweak constraints. The LHC constraints on the and couplings are satisfied by being close to the "alignment limit". We find how fine-tuned the model is after including these constraints. For the points that satisfy the constraints, we present the 1-loop effective couplings of the CP-even and CP-odd neutral scalars to two gluons including contributions of standard model and heavy vector-like quarks. We also present the branching ratios of the heavy neutral scalars into the modes, and the heavy charged scalar into modes. These will aid searches of the heavy scalars at the LHC and other future colliders.
Wei Chao🇺🇸 · Ran Huo🇯🇵 · Jiang-Hao Yu🇺🇸
A resonance near 750 GeV has been observed at both the ATLAS and CMS experiments in its diphoton decay channel. We propose a possible interpretation based on a simplified model: a 750 GeV singlet scalar resonance, and a minimal stealth vector quark are introduced. At the LHC, the scalar is produced through gluon fusion, and subsequently decays to diphoton final state. The light stealth quarks could enhance the diphoton rate significantly, while still keeping other channels below the current LHC search limits. We find that the stealth quarks around 400 ~ 500 GeV with its coupling to scalar around 0.5 ~ 1.5 could explain the diphoton excess, and avoid current di-jet constraints. We also comment on other potential signatures of this stealth model.
Sylvain Fichet🇧🇷 · Gero von Gersdorff🇧🇷 · Christophe Royon🇺🇸
We consider the possibility that the diphoton excess at 750 GeV is caused by a new scalar resonance produced in photon fusion. This scenario is parametrised by only one relevant effective couplings and is thus minimal. We show that this setup can reproduce both the production rate and width of the resonance, and is not in conflict with the 8 TeV limits on the diphoton cross section. The scenario also predicts event rates for , , final states. We suggest to perform precision measurements by studying light-by-light scattering with intact protons detected in forward detectors. We construct a simple model that shows that the required couplings can be achieved with new vectorlike, uncolored fermions (with a strong Yukawa coupling to the resonance) which may also account for the required width.
David Curtin🇺🇸 · Christopher B. Verhaaren🇺🇸
We propose two simple quirk models to explain the recently reported 750 GeV diphoton excesses at ATLAS and CMS. It is already well-known that a real singlet scalar with Yukawa couplings to vector-like fermions with mass can easily explain the observed signal, provided carries both SM color and electric charge. We instead consider first the possibility that the pair production of a fermion, charged under both SM gauge groups and a confining gauge group, is responsible. If pair produced it forms a quirky bound state, which promptly annihilates into gluons, photons, v-gluons and possibly SM fermions. This is an extremely minimal model to explain the excess, but is already in some tension with existing displaced searches, as well as dilepton and dijet resonance bounds. We therefore propose a hybrid Quirk-Scalar model, in which the fermion of the simple toy model is charged under the additional confining gauge group. Constraints on the new heavy fermion are then significantly relaxed. The main additional signals of this model are possible dilepton, dijet and diphoton resonances at 2 TeV or more from quirk annihilation, and the production of v-glueballs through quirk annihilation and decay. The glueballs can give rise to spectacular signatures, including displaced vertices and events with leptons, photons and -bosons. If the Quirk-Scalar model is responsible for the 750 GeV excess it should be discovered in one of these channels with 20 or of LHC run 2 data.
Ligong Bian🇨🇳 · Ning Chen🇨🇳 · Da Liu🇨🇳 · Jing Shu🇨🇳
We explain the recent diphoton excesses around GeV by both ATLAS and CMS as a singlet scalar which couples to SM gluon and neutral gauge bosons only through higher dimensional operators. A natural explanation is that is a pseudo-Nambu-Goldstone boson (pNGB) which receives parity violation through anomaly if there exists a hidden strong dynamics. The singlet and other light pNGBs will decay into two SM gauge bosons and even serves as the meta-stable coloured states which can be probed in the future. By accurately measuring their relative decay and the total production rate in the future, we will learn the underlying strong dynamics parameter. The lightest baryon in this confining theory could serve as a viable dark matter candidate.
Joydeep Chakrabortty🇮🇳 · Arghya Choudhury🇬🇧 · Pradipta Ghosh🇫🇷 · Subhadeep Mondal🇮🇳 · Tripurari Srivastava🇮🇳
Both the ATLAS and CMS collaborations have recently observed an excess in the di-photon invariant mass distribution in the vicinity of 750 GeV with a local significance of . In this article we try to investigate this excess in the context of a minimal simplified framework assuming effective interactions of the hinted resonance with photons and gluons. We scrutinise the consistency of this observation with possible accompanying yet hitherto unseen signatures of this resonance. Subsequently, we try to probe the nature of new particles, e.g., spin, electric charge and number of colour, etc., that could remain instrumental to explain this excess through loop-mediation.
Aqeel Ahmed🇵🇱 · Barry M. Dillon🇬🇧 · Bohdan Grzadkowski🇵🇱 · John F. Gunion🇺🇸 · Yun Jiang🇩🇰
Given the disappearance of the 750 GeV di-photon LHC signal and the absence of signals at high mass in this and other channels, significant constraints on the mixed Higgs-radion of the five-dimensional Randall-Sundrum model arise. By combining all channels, these constraints place a significant radion-mass-dependent lower bound on the radion vacuum expectation value that is fairly independent of the amount of Higgs radion mixing.
Prateek Agrawal🇺🇸 · JiJi Fan🇺🇸 · Ben Heidenreich🇺🇸 · Matthew Reece🇺🇸 · Matthew Strassler🇺🇸
We consider the immediate or near-term experimental opportunities offered by some scenarios that could explain the new diphoton excess at the LHC. If the excess is due to a new particle at 750 GeV, additional new particles are required, providing further signals. If connected with naturalness, the may be produced in top partner decays. Then a signal, with and dominantly, might be discovered by reinterpreting 13 TeV SUSY searches in multijet events with low MET and/or a lepton. If is a bound state of quirks, the signal events may be accompanied by an unusual number of soft tracks or soft jets. Other resonances including dilepton and photon+jet as well as dijet may lie at or above this mass, and signatures of hidden glueballs might also be observable. If the "photons" in the excess are actually long-lived particles decaying to photon pairs or to electron pairs, there are opportunities for detecting overlapping photons and/or unusual patterns of apparent photon-conversions in either or 125 GeV Higgs decays. There is also the possibility of events with a hard "photon" recoiling against a narrow isolated HCAL-only "jet", which, after the jet's energy is corrected for its electromagnetic origin, would show a peak at 750 GeV.
Csaba Csaki🇺🇸 · Jay Hubisz🇺🇸 · John Terning🇺🇸
We consider the phenomenology of a resonance that couples to photons but not gluons, and estimate its production rate at the LHC from photon-photon fusion in elastic pp scattering using the effective photon and narrow width approximations. The rate is sensitive only to the mass, the spin, the total width of the resonance, and its branching fraction to photons. Production cross sections of 5-10 fb at 13 TeV can be easily accommodated for a 750 GeV resonance with partial photon width of 15 GeV. This provides the minimal explanation of the reported diphoton anomaly in the early LHC Run II data.
Adam Falkowski🇫🇷 · Oren Slone🇮🇱 · Tomer Volansky🇮🇱
We study the recently reported excess in the diphoton resonance search by ATLAS and CMS. We investigate the available parameter space in the combined run-1 and run-2 diphoton data and study its interpretation in terms of a singlet scalar field which possibly mixes with the Standard Model Higgs boson. We show that the mixing angle is already strongly constrained by high-mass Higgs searches in the diboson channel, and by Higgs coupling measurements. While a broad resonance is slightly favored, we argue that the signal is consistent with a narrow-width singlet which couples to colored and electromagnetically-charged vector-like fermions. Dijet signals are predicted and may be visible in upcoming analyses. Allowing for additional decay modes could explain a broader resonance, however, we show that monojet searches disfavor a large invisible width. Finally, we comment on the possible relation of this scenario to the naturalness problem.
Daniel Aloni🇮🇱 · Kfir Blum🇮🇱 · Avital Dery🇮🇱 · Aielet Efrati🇮🇱 · Yosef Nir🇮🇱
The ATLAS and CMS experiments at the LHC have reported an excess of diphoton events with invariant mass around 750 GeV, with local significance of about and , respectively. We entertain the possibility that this excess is due to new physics, in which case the data suggest a new particle with 13 TeV LHC production cross section times diphoton branching ratio of about 5~fb. Interestingly, ATLAS reports a mild preference for a sizeable width for the signal of about 45 GeV; this result appears consistent with CMS, and is further supported by improving the compatibility of the 8 TeV and 13 TeV analyses. We focus on the possibility that the new state is a scalar. First, we show that, in addition to the new state that is needed directly to produce the diphoton bump, yet more new particles beyond the Standard Model are needed to induce diphoton decay rate of the right size. Second, we note that if the excess is attributed to the Breit-Wigner peak of a single new state, then the signal strength and width -- taken together -- suggest a total LHC production cross section of order fb. Restricting to perturbative models without ad-hoc introduction of many new states or exotic charges, we reach the following conclusions: (i) Gluon-fusion cannot explain the required large production cross section. (ii) Tree level production from initial state quarks cannot explain the required branching ratio to two photons. (iii) Tree level production is constrained by flavor data as well as LHC Run-I and Tevatron dijet analyses. Insisting on a large width we are led to suggest that more than one scalar states, nearly degenerate in mass, could conspire to produce an observed wide bump.
Yang Bai🇺🇸 · Joshua Berger🇺🇸 · Ran Lu🇺🇸
We point out a potential common origin of the recently observed 750 GeV diphoton resonance and a Weakly Interacting Massive Particle (WIMP) candidate. In a dark QCD sector with an unbroken dark G-parity, the diphoton resonance could be a dark G-even pion, while the WIMP could be the lightest dark G-odd pion. Both particles are Standard Model gauge singlets and have the same decay constant. For the dark pion decay constant of around 500 GeV, both the diphoton excess at the LHC and the dark matter thermal abundance can be accommodated in our model. Our model predicts additional dark G-even and dark G-odd color-octet pions within reach of the 13 TeV LHC runs. For the 5 + 5bar model, compatible with the Grand Unified Theories, the WIMP mass is predicted to be within (613, 750) GeV.
JiJi Fan🇺🇸 · Rebecca Krall🇺🇸 · David Pinner🇺🇸 · Matthew Reece🇺🇸 · Joshua T. Ruderman🇺🇸
In Stealth Supersymmetry, bounds on superpartners from direct searches can be notably weaker than in standard supersymmetric scenarios, due to suppressed missing energy. We present a set of simplified models of Stealth Supersymmetry that motivate 13 TeV LHC searches. We focus on simplified models within the Natural Supersymmetry framework, in which the gluino, stop, and Higgsino are assumed to be lighter than other superpartners. Our simplified models exhibit novel decay patterns that differ significantly from topologies of the Minimal Supersymmetric Standard Model, with and without -parity. We determine limits on stops and gluinos from searches at the 8 TeV LHC. Existing searches constitute a powerful probe of Stealth Supersymmetry gluinos with certain topologies. However, we identify simplified models where the gluino can be considerably lighter than 1 TeV. Stops are significantly less constrained in Stealth Supersymmetry than the MSSM, and we have identified novel stop decay topologies that are completely unconstrained by existing LHC searches.
Zackaria Chacko🇺🇸 · David Curtin🇺🇸 · Christopher B. Verhaaren🇺🇸
We consider the signals arising from top partner pair production at the LHC as a probe of theories of Neutral Naturalness. We focus on scenarios in which top partners carry electroweak charges, such as Folded SUSY or the Quirky Little Higgs. In this class of theories the top partners are pair produced as quirky bound states, since they are charged under a mirror color group whose lightest states are hidden glueballs. The quirks promptly de-excite and annihilate into glueballs, which decay back to SM fermions via Higgs mixing. This can give rise to spectacular signatures at the LHC, such displaced decays, or high-multiplicity prompt production of many hard or pairs. We show that signals arising from top partner pair production constitute the primary discovery channel for this class of theories in most regions of parameter space, and might provide the only experimental probe of scenarios with sub-cm glueball decay lengths. The measurement of top partner masses and couplings, which could be used to test the neutral naturalness mechanism directly, is also a tantalizing possibility.
Swagata Ghosh🇮🇳 · Anirban Kundu🇮🇳 · Shamayita Ray🇮🇳
We investigate the parameter space of the Standard Model enhanced by a gauge singlet real scalar . Taking into account all the theoretical and experimental constraints, we show the allowed parameter space for two different types of such singlet-enhanced Standard Model. For the first case, the scalar potential has an explicit -symmetry, and may lead to a dark matter candidate under certain conditions. For the second case, the scalar potential does not respect any . This is again divided into two subcategories: one where the Standard Model vacuum is stable, and one where it is unstable and can decay into a deeper minimum. We show how the parameters in the scalar potential control the range of validity of all these models. Finally, we show the effect of one-loop correction on the positions and depths of the minima of the potential.
After the discovery of a Higgs boson in 2012 at the CERN Large Hadron Collider (LHC) the detailed study of its properties, and most importantly its couplings to other particles, has started. This is a very important task to be completed, in particular to test whether it is indeed the Higgs boson predicted by the Standard Model (SM). The precise study of the Higgs couplings to gauge bosons is of particular importance and requires as much information as possible. In this view this paper provides the next-to-leading order (NLO) QCD corrections to the production cross sections and differential distributions of a SM Higgs boson in association with a pair of weak bosons , and , matched with parton shower (PS) in the POWHEG-BOX framework. The NLO QCD corrections are found to be significant and PS effects are sizable at low in the jet differential distributions, as expected, while these effects are negligible in other distributions. We will also provide a detailed study of the theoretical uncertainties affecting the total production rates at the LHC and at the Future Circular Collider in hadron-hadron mode, the potential 100 TeV follow-up of the LHC machine: the scale uncertainty calculated by the variation of the renormalization and factorization scales, the parton distribution function and related errors as well as the parametric uncertainties on the input weak boson masses.
Yoshitaka Hatta🇯🇵 · Yoshikazu Hagiwara🇯🇵
We define the QCD Husimi distribution as the phase space distribution of partons inside the nucleon. Compared to the more well-known Wigner distribution, the Husimi distribution is better behaved and positive. It thus allows for a probabilistic interpretation and can be used to define the `entropy' of the nucleon as a measure of complexity of the partonic structure. A possible connection to the Color Glass Condensate approach at small- is also discussed.
Shinsuke Kawai🇰🇷 · Jinsu Kim🇰🇷
We study the Higgs inflation model realized in the supersymmetric SU(5) grand unified theory (GUT), focusing on its multifield dynamics and prediction of cosmological observables. The requirement for GUT symmetry breaking during inflation imposes tight constraints on the model parameters. We find, nevertheless, with an appropriately chosen noncanonical Kahler potential the model is in excellent agreement with the present cosmological observation. The effects from multifield dynamics is found to be minor and thus, unlike other similar supersymmetric implementation of nonminimally coupled Higgs inflation, the prediction of this model is robust against multifield ambiguities.
Wan-Li Ju🇨🇳 · Tianhong Wang🇨🇳 · Yue Jiang🇨🇳 · Han Yuan🇨🇳 · Guo-Li Wang🇨🇳
In this paper, with the framework of (p)NRQCD and SCET, the processes are investigated. Here denotes the light charmless meson, such as , , or . Based on the SCET power counting rules, the leading transition amplitudes are picked out, which include , , , and . From SCET, their factorization formulae are proven. Based on the obtained factorization formulae, in particular, the numerical calculation on is performed.
We present an overview of the options for diffraction implemented in the general-purpose event generator Pythia 8. We review the existing model for soft diffraction and present a new model for hard diffraction. Both models use the Pomeron approach pioneered by Ingelman and Schlein, factorising the diffractive cross section into a Pomeron flux and a Pomeron PDF, with several choices for both implemented in Pythia 8. The model of hard diffraction is implemented as a part of the multiparton interactions (MPI) framework, thus introducing a dynamical gap survival probability that explicitly breaks factorisation.
Arsham Farzinnia🇰🇷 · Seyen Kouwn🇰🇷
We introduce a minimal and yet comprehensive framework with - and classical scale-symmetries, in order to simultaneously address the hierarchy problem, neutrino masses, dark matter, and inflation. One complex gauge singlet scalar and three flavors of the right-handed Majorana neutrinos are added to the standard model content, facilitating the see-saw mechanism, among others. An adimensional theory of gravity (Agravity) is employed, allowing for the trans-Planckian field excursions. The weak and Planck scales are induced by the Higgs portal and the scalar non-minimal couplings, respectively, once a Coleman-Weinberg dynamically-generated vacuum expectation value for the singlet scalar is obtained. All scales are free from any mutual quadratic destabilization. The -symmetry prevents a decay of the pseudoscalar singlet, rendering it a suitable WIMPzilla dark matter candidate with the correct observational relic abundance. Identifying the pseudo-Nambu-Goldstone boson of the (approximate) scale symmetry with the inflaton field, the model accommodates successful slow-roll inflation, compatible with the observational data. We reach the conclusion that a pseudo-Nambu-Goldstone inflaton, within a classically scale-symmetric framework, yields lighter WIMPzillas.
We reinterpret the results of the direct searches for dark matter in terms of composite dark matter, i.e. dark matter particles that form neutral bound states, generically called dark atoms, either with ordinary particles, or with other dark matter particles. Three different scenarios are investigated: the O-helium scenario, milli- interacting dark matter and dark anti-atoms. In each of them, dark matter interacts sufficiently strongly with terrestrial matter to be stopped in it before reaching underground detectors. As they drift towards the center of the earth by gravity, these thermal dark atoms are radiatively captured by the atoms of the active medium of underground detectors, which causes the emission of photons that produce the signals through their interactions with the electrons of the medium. This provides a way of reinterpreting the results in terms of electron recoils instead of nuclear recoils. The detailed study of the interactions of O-helium with ordinary matter shows that it is not an acceptable candidate for dark matter because of the absence of a repulsion mechanism preventing it from falling into the deep nuclear wells of nuclei. The two other models involve milli-charges and are able to reconcile the most contradictory experiments. We determine, for each model, the regions in the parameter space that reproduce the experiments with positive results in full consistency with the constraints of the experiments with negative results. We also pay attention to the experimental and observational constraints on milli-charges and discuss some typical signatures of the models that could be used to test them.
E. Gabrielli🇮🇹 · K. Kannike🇪🇪 · B. Mele🇮🇹 · M. Raidal🇪🇪 · C. Spethmann🇪🇪 · H. Veermäe🇪🇪
The evidence for a new singlet scalar particle from the 750 GeV diphoton excess, and the absence of any other signal of new physics at the LHC so far, suggest the existence of new coloured scalars. To study this possibility, we propose a supersymmetry inspired simplified model, extending the Standard Model with a singlet scalar and with heavy scalar fields carrying both colour and electric charges -- the `squarks'. To allow the latter to decay, and to generate the dark matter of the Universe, we also add a neutral fermion to the particle content. We show that this model provides a two-parameter fit to the observed diphoton excess consistently with cosmology, while the allowed parameter space is bounded by the consistency of the model. In the context of our simplified model this implies the existence of other supersymmetric particles accessible at the LHC, rendering this scenario falsifiable. If this excess persists, it will imply a paradigm shift in assessing supersymmetry breaking and the role of scalars in low scale physics.
G. Bailas🇫🇷 · V. P. Goncalves🇧🇷
In this paper we study the , jet, and jet production in collisions at the LHC considering different models for an intrinsic charm content of the proton. We analyse the impact of the intrinsic charm in the rapidity and transverse momentum distributions for these different processes. Our results indicated that differently from the other processes, the cross section is strongly affected by the presence of the intrinsic charm. Moreover, we propose the analysis of the ratios and and demonstrate that these observables can be used as a probe of the intrinsic charm.
G. Calucci🇮🇹 · R. Iengo🇮🇹
We propose to use the change of the energy lost by ionization, measured by silicon detectors, before and after the passage through a bulk of dense matter, for unambiguously detecting highly massive single-charged particles, which could be produced at LHC, in particular Winos with mass in the TeV range, whose c-tau is expected to be some cms long, although the method is also efficient for masses down to 10GeV. For convenience, a QED derivation of the modern version of the Bethe-Block formula is also provided.
R. Benbrik🇲🇦 · Chuan-Hung Chen🇹🇼 · Takaaki Nomura🇰🇷
ATLAS and CMS recently show the first results from run 2 of the Large Hadron Collider (LHC) at TeV. A resonant bump at a mass of around 750 GeV in the diphoton invariant mass spectrum is indicated and the corresponding diphoton production cross section is around 3-10 fb. Motivated by the LHC diphoton excess, we propose that the possible resonance candidate is a Higgs singlet. To produce the Higgs singlet via gluon-gluon fusion process, we embed the Higgs singlet in the framework of vector-like triplet quark (VLTQ) model. As a result, the Higgs singlet decaying to diphoton final state is via VLTQ loops. Using the enhanced number of new quarks and new Yukawa couplings of the VLTQs and Higgs singlet, we successfully explain the diphoton production cross section. We find that the width of the Higgs singlet is below 1 GeV, its production cross section can be of order of 1 pb at TeV, and the branching ratio for it decaying to diphoton is around and is insensitive to the masses of VLTQs and new Yukawa couplings. We find a strong correlation between the Higgs Yukawa couplings to - and -; the resulted branching ratio for can be when the constraint from oscillation is applied. With the constrained parameter values, the signal strength for the SM Higgs decaying to diphoton is , which is consistent with the current measurements at ATLAS and CMS.
Stefan Antusch🇨🇭 · Eros Cazzato🇨🇭 · Oliver Fischer🇨🇭
In scenarios with sterile (right-handed) neutrinos that are subject to an approximate "lepton-number-like" symmetry, the heavy neutrinos (i.e. the mass eigenstates) can have masses around the electroweak scale and couple to the Higgs boson with, in principle, unsuppressed Yukawa couplings while accounting for the smallness of the light neutrinos' masses. In these scenarios, the on-shell production of heavy neutrinos and their subsequent decays into a light neutrino and a Higgs boson constitutes a hitherto unstudied resonant contribution to the Higgs production mechanism. We investigate the relevance of this resonant mono-Higgs production mechanism in leptonic collisions, including the present experimental constraints on the neutrino Yukawa couplings, and we determine the sensitivity of future lepton colliders to the heavy neutrinos. With Monte Carlo event sampling and a simulation of the detector response we find that, at future lepton colliders, neutrino Yukawa couplings below the percent level can lead to observable deviations from the SM and, furthermore, the sensitivity improves with higher center-of-mass energies (for identical integrated luminosities).
C. Lorcé (Ecole Polytechnique, CPHT)🇫🇷 · B. Pasquini (Pavia U. & INFN, Pavia)🇮🇹
We present a complete study of the leading-twist quark Wigner distributions in the nucleon, discussing both the -even and -odd sector, along with all the possible configurations of the quark and nucleon polarizations. We identify the basic multipole structures associated with each distribution in the transverse phase space, providing a transparent interpretation of the spin-spin and spin-orbit correlations of quarks and nucleon encoded in these functions. Projecting the multipole parametrization of the Wigner functions onto the transverse-position and the transverse-momentum spaces, we find a natural link with the corresponding multipole parametrizations for the generalized parton distributions and transverse-momentum dependent parton distributions, respectively. Finally, we show results for all the distributions in the transverse phase space, introducing a representation that allows one to visualize simultaneously the multipole structures in both the transverse-position and transverse-momentum spaces.
X.-G. Lu🇬🇧 · L. Pickering🇬🇧 · S. Dolan🇬🇧 · G. Barr🇬🇧 · D. Coplowe🇬🇧 · Y. Uchida🇬🇧 · D. Wark🇬🇧 · M. O. Wascko🇬🇧 · A. Weber🇬🇧 · T. Yuan🇺🇸
We present a phenomenological study of nuclear effects in neutrino charged-current interactions, using transverse kinematic imbalances in exclusive measurements. Novel observables with minimal dependence on neutrino energy are proposed to study quasielastic scattering, and especially resonance production. They should be able to provide direct constraints on nuclear effects in neutrino- and antineutrino-nucleus interactions.
Diego Blas🇨🇭 · Mathias Garny🇨🇭 · Mikhail M. Ivanov🇨🇭 · Sergey Sibiryakov🇨🇭
We present a new analytic approach to describe large scale structure formation in the mildly non-linear regime. The central object of the method is the time-dependent probability distribution function generating correlators of the cosmological observables at a given moment of time. Expanding the distribution function around the Gaussian weight we formulate a perturbative technique to calculate non-linear corrections to cosmological correlators, similar to the diagrammatic expansion in a three-dimensional Euclidean quantum field theory, with time playing the role of an external parameter. For the physically relevant case of cold dark matter in an Einstein--de Sitter universe, the time evolution of the distribution function can be found exactly and is encapsulated by a time-dependent coupling constant controlling the perturbative expansion. We show that all building blocks of the expansion are free from spurious infrared enhanced contributions that plague the standard cosmological perturbation theory. This paves the way towards the systematic resummation of infrared effects in large scale structure formation. We also argue that the approach proposed here provides a natural framework to account for the influence of short-scale dynamics on larger scales along the lines of effective field theory.
M. A. L. Capri🇧🇷 · D. Dudal🇧🇪 · D. Fiorentini🇧🇷 · M. S. Guimaraes🇧🇷 · I. F. Justo🇧🇪 · B. W. Mintz🇧🇷 · L. F. Palhares🇧🇷 · A. D. Pereira🇧🇷 · R. F. Sobreiro🇧🇷 · S. P. Sorella🇧🇷
In this paper, we discuss the gluon propagator in the linear covariant gauges in Euclidean dimensions. Non-perturbative effects are taken into account via the so-called Refined Gribov-Zwanziger framework. We point out that, as in the Landau and maximal Abelian gauges, for , the gluon propagator displays a massive (decoupling) behaviour, while for , a scaling one emerges. All results are discussed in a setup that respects the Becchi-Rouet-Stora-Tyutin (BRST) symmetry, through a recently introduced non-perturbative BRST transformation. We also propose a minimizing functional that could be used to construct a lattice version of our non-perturbative definition of the linear covariant gauge.
Qing-Guo Huang🇨🇳 · Ke Wang🇨🇳 · Sai Wang🇨🇳
Considering the mass splitting between three active neutrinos, we represent the new constraints on the sum of neutrino mass by updating the anisotropic analysis of Baryon Acoustic Oscillation (BAO) scale in the CMASS and LOWZ galaxy samples from Data Release 12 of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS DR12). Combining the BAO data of 6dFGS, MGS, LOWZ and CMASS with ~2015 data of temperature anisotropy and polarizations of Cosmic Microwave Background (CMB), we find that the C.L. upper bounds on refer to eV for normal hierarchy (NH), eV for inverted hierarchy (IH) and eV for degenerate hierarchy (DH) respectively, and the normal hierarchy is slightly preferred than the inverted one (). In addition, the additional relativistic degrees of freedom and massive sterile neutrinos are neither favored at present.
Searches for supersymmetry (SUSY) at the LHC frequently assume the conservation of -parity in their design, optimization and interpretation. In the case that -parity is not conserved, constraints on SUSY particle masses tend to be weakened with respect to -parity-conserving models. We review the current status of searches for -parity-violating (RPV) supersymmetry models at the ATLAS and CMS experiments, limited to 8 TeV search results published or submitted for publication as of the end of March 2015. All forms of renormalisable RPV terms leading to prompt signatures have been considered in the set of analyses under review. Discussing results for searches for prompt R-parity-violating SUSY signatures summarizes the main constraints for various RPV models from LHC Run I and also defines the basis for promising signal regions to be optimized for Run II. In addition to identifying highly constrained regions from existing searches, also gaps in the coverage of the parameter space of RPV SUSY are outlined.
Michele Modugno🇪🇸 · Julen Ibañez-Azpiroz🇩🇪 · Giulio Pettini🇮🇹
Tight-binding models for ultracold atoms in optical lattices can be properly defined by using the concept of maximally localized Wannier functions for composite bands. The basic principles of this approach are reviewed here, along with different applications to lattice potentials with two minima per unit cell, in one and two spatial dimensions. Two independent methods for computing the tight-binding coefficients - one ab initio, based on the maximally localized Wannier functions, the other through analytic expressions in terms of the energy spectrum - are considered. In the one dimensional case, where the tight-binding coefficients can be obtained by designing a specific gauge transformation, we consider both the case of quasi resonance between the two lowest bands, and that between s and p orbitals. In the latter case, the role of the Wannier functions in the derivation of an effective Dirac equation is also reviewed. Then, we consider the case of a two dimensional honeycomb potential, with particular emphasis on the Haldane model, its phase diagram, and the breakdown of the Peierls substitution. Tunable honeycomb lattices, characterized by movable Dirac points, are also considered. Finally, general considerations for dealing with the interaction terms are presented.
* 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.