HEP Phenomenology·hep-ph

Tue·Jul 23, 2019Tuesday·July 23, 2019

43 papers—31 primary·12 cross-listed·reconstructed*

01*
Probing quark transversity GPDs in diffractive photo- and electroproduction on the deuteron
W. Cosyn🇧🇪 · B. Pire🇫🇷 · L. Szymanowski🇵🇱
Transversity generalized parton distributions (GPDs) can be probed in diffractive electro- and photoproduction of two vector mesons on a hadron in kinematics where the two vector mesons are separated by a large rapidity gap. We report on calculations for this process in the case of coherent $ρ^{0} - ω$ meson production on a deuteron target. Our cross section results show that an electron-ion collider with deuteron beams and forward detectors could probe deuteron transversity GPDs.
hep-phnucl-exnucl-thPoS(2019)·5 citations
02*
Extraction of multiple parton interactions and color reconnection from forward-backward multiplicity correlations
Eleazar Cuautle🇲🇽 · Edgar Dominguez🇲🇽 · Ivonne Maldonado🇲🇽
Forward-backward multiplicity correlations have been studied in electron-positron, proton-proton and more recently in lead-lead collisions. For the proton-proton case, comparison of experimental results to different models reveals an incomplete understanding of the physical phenomenon associated with these correlations. In this work, we present a study of forward-backward multiplicity correlations in proton-proton collisions using the PYTHIA event generator, at LHC energies. A detailed analysis is presented with and without weak decays, splitting data samples into soft and hard QCD processes, and comparing the computed correlations for short and long range pseudorapidity regions. Each of these regions is analyzed accounting for the effects of color reconnection and independent multiple parton interactions. We show that a combination of these effects is required to explain the latest measurements on proton-proton data. Furthermore, is shown that from measurements of multiplicity correlations is possible to extract the average number of multiple parton interactions in the event producing these correlations, and albeit model depending, to predict the strength of these correlations, not yet measured, for higher energy collisions.
hep-phnucl-thEPJC(2019)·8 citations
03*
The analysis of the excited bottom and bottom strange states $B_{1} (5721)$ , $B_{2}^{*} (5747)$ , $B_{s 1} (5830)$ , $B_{s 2}^{*} (5840)$ , $B_{J} (5840)$ and $B_{J} (5970)$ in B meson family
Guo-Liang Yu🇨🇳 · Zhi-Gang Wang🇨🇳
In order to make a further confirmation about the assignments of the excited bottom and bottom strange mesons $B_{1} (5721)$ , $B_{2}^{*} (5747)$ , $B_{s 1} (5830)$ , $B_{s 2}^{*} (5840)$ and meanwhile identify the possible assignments of $B_{J} (5840)$ , $B_{J} (5970)$ , we study the strong decays of these states with the $^{3} P_{0}$ decay model. Our analysis support $B_{1} (5721)$ and $B_{2}^{*} (5747)$ to be the $1 P_{1}^{'}$ and $1^{3} P_{2}$ assignments and the $B_{s 1} (5830)$ , $B_{s 2}^{*} (5840)$ to be the strange partner of $B_{1} (5721)$ and $B_{2}^{*} (5747)$ . Besides, we tentatively identify the recently observed $B_{J} (5840)$ , $B_{J} (5970)$ as the $2^{3} S_{1}$ and $1^{3} D_{3}$ states, respectively. It is noticed that this conclusion needs further confirmation by measuring the decay channel to $B π$ of $B_{J} (5840)$ and $B_{J} (5970)$ in experiments.
hep-phCPC(2020)·15 citations
04*
Evaluation of the $B_{c}^{+} \to D^{0} K^{+}$ decay by the factorization approaches and applying the effects of the final state interaction
Behnam Mohammadi🇮🇷 · Mahdi Lotfizadeh🇮🇷
In this paper the decay of $B_{c}^{+}$ meson, consisting of two b and c heavy quarks, into the $D^{0}$ and $K^{+}$ mesons is studied. Given that the experimental branching ratio for this decay is within the range of $3.72 \times 1 0^{- 5}$ to $11.16 \times 1 0^{- 5}$ and in our estimating the theoretical result by using the QCD factorization approaches is $1 0^{2}$ times less than experimental one (we have obtained $1.41 \times 1 0^{- 7}$ ), it is decided to calculate the theoretical branching ratio by applying the final state interaction (FSI) through the T and cross section channels. In this process, before the $B_{c}^{+}$ meson decays into two final state mesons of $D^{0} K^{+}$ , it first decays into two intermediate mesons like $J / ψ D_{s}^{*+}$ , then these two mesons transformed into two final mesons by exchanging another meson like $D^{0}$ . The FSI effects are very sensitive to the changes in the phenomenological parameter that appear in the form factor relation, as in most calculation changing two units in this parameter, makes the final result multiply in the branching ratio, therefor the decision to use FSI is not unexpected. In this study there are nineteen intermediate states in which the contribution of each one is calculated and summed in the final amplitude. Therefore, the numerical value of the branching ratio of $B_{c}^{+} \to D^{0} K^{+}$ decay is obtained by calculating the FSI effects from $1.17 \times 1 0^{- 5}$ to $11.65 \times 1 0^{- 5}$ which is consistent with the experimental result.
hep-phPhys.Scripta(2020)·3 citations
05*
ITMD factorization and broadening effects in production of forward di-jets
Krzysztof Kutak🇵🇱
I report on the recent result of comparison of forward-forward dijet correlations in azimuthal angle as measured by the ATLAS collaboration in the proton-proton and proton-lead collisions to calculations within ITMD factorization framework [1]. The comparison shows that the broadening effect due to interplay of both the gluon saturation and the Sudakov resummation is necessary to describe the data.
hep-phPoS(2019)·0 citations
06*
Explicit Jet Veto as a Tool to Purify the Underlying Event in the Drell-Yan Process Using CMS Open Data
Saeid Paktinat Mehdiabadi🇮🇷 · Ali Fahim🇮🇷
The underlying event is an important part of high-energy collision events. In the event generators, the underlying event is tuned by fits to collision data. Usually, the underlying event observables are affected by the existence of extra jets and it is difficult to find a part of the phase space which is dominated by the underlying event. In this paper, we suggest to veto the jets in the considered region to disentangle these effects. The idea is verified to work on CMS Open Data. To our knowledge, it is the first time that such ideas are tested on real collision data.
hep-phhep-exJ.Phys.G(2019)·6 citations
07*
Gravitational waves from scale-invariant vector dark matter model: Probing below the neutrino-floor
Ahmad Mohamadnejad🇮🇷
We study the gravitational waves (GWs) spectrum produced during the electroweak phase transition in a scale-invariant extension of the Standard Model (SM), enlarged by a dark $U (1)_{D}$ gauge symmetry. This symmetry incorporates a vector dark matter (DM) candidate and a scalar field (scalon). Because of scale invariance, the model has only two independent parameters and for the parameter space constrained by DM relic density, strongly first-order electroweak phase transition can take place. In this model, for a narrow part of the parameter space, DM-nucleon cross section is below the neutrino-floor limit, and therefore, it cannot be probed by the future direct detection experiments. However, for a benchmark point form this narrow region, we show the amplitude and frequency of phase transition GW spectrum fall within the observational window of space-based GW detectors such as eLISA.
hep-phgr-qcEPJC(2020)·79 citations
08*
Production of $W^{+} W^{-}$ and $t t ˉ$ pairs via photon-photon processes in proton-proton collisions
Antoni Szczurek🇵🇱 · Marta Luszczak🇵🇱
We review our recent results for production of $W^{+} W^{-}$ and $t t ˉ$ pairs via photon-photon fusion. A theoretical approach is presented in short. We include transverse momenta of photons when calculating fluxes of photons. Then we discuss our results for cross section (total and differential) for $W^{+} W^{-}$ production. Results for different parametrizations of proton structure functions are used to calculate inelastic fluxes of photons. A discussion on rapidity gap survival probability due to remnant fragmentation is presented. A similar discussion is presented for $t t ˉ$ production.
hep-phhep-exPoS(2019)·2 citations
09*
Searching for odderon in exclusive reactions: $pp \to ppp p ˉ$ , $pp \to ppϕϕ$ and $pp \to ppϕ$
Antoni Szczurek🇵🇱 · Piotr Lebiedowicz🇵🇱
There seem to be recently an evidence for $C =$ -1 exchanges in $pp$ and $p p ˉ$ elastic scattering at high energies. The analysis there is difficult as the two processes were not measured at the same (large) energies. Here we discuss three different exclusive processes given in the title as a possible source of information for odderon exchange. A sketch of the formalism is presented for each of the reactions. We consider low energy processes measured in the past by the WA102 collaboration and try to make predictions for the LHC. We discuss possible evidences at the low energies and try to make suggestions for the LHC.
hep-phhep-exPoS(2019)·2 citations
10*
Matter vs Vacuum oscillations in Atmospheric Neutrinos
Mohammad Nizam🇮🇳 · Jaydeep Datta🇮🇳 · Ali Ajmi🇯🇵 · S. Uma Sankar🇮🇳
Atmospheric neutrinos travel very long distances through earth matter. It is expected that the matter effects lead to significant changes in the neutrino survival and oscillation probabilities. Initial analysis of atmospheric neutrino data by the Super- Kamiokande collaboration is done using the vacuum oscillation hypothesis, which provided a good fit to the data. In this work, we did a study to differentiate the effects of vacuum oscillations and matter modified oscillations in the atmospheric neutrino data. We find that magnetized iron detector, ICAL at INO, can make a 3 sigma discrimination between vacuum oscillations and matter oscillations, for both normal and inverted hierarchies, in ten years.
hep-phNPB(2020)·6 citations
11*
Coherent Showers in Decays of Colored Resonances
Helen Brooks🇦🇺 · Peter Skands🇦🇺
We present a new approach to coherent parton showers in the decays of coloured resonances, based on the notion of "resonance-final" (RF) QCD antennae. A full set of mass- and helicity-dependent $2 \to 3$ antenna functions are defined, with the additional requirement of positivity over the respective branching phase spaces. Their singularity structure is identical to that of initial-final (IF) antennae in $2 \to N$ hard processes (once mass terms associated with the incoming legs are allowed for), but the phase-space factorisations are different. The consequent radiation patterns respect QCD coherence (at leading colour) and reduce to Dokshitzer-Gribov-Lipatov-Altarelli-Parisi and eikonal kernels in the respective collinear and soft limits. The main novelty in the phase-space factorisation is that branchings in RF antennae impart a collective recoil to the other partons within the same decay system. An explicit implementation of these ideas, based on the Sudakov veto algorithm, is provided in the VINCIA antenna-shower plug-in to the PYTHIA 8 Monte Carlo event generator. We apply our formalism, matched to next-to-leading order accuracy using POWHEG, to top quark production at the LHC, and investigate implications for direct measurement of the top quark mass. Finally, we make recommendations for assessing theoretical uncertainties arising from parton showers in this context.
hep-phhep-exPRD(2019)·41 citations
12*
Polarisabilities of the nucleon in baryon chiral perturbation theory and beyond
Vadim Lensky🇩🇪 · Vladimir Pascalutsa🇩🇪
We review the recent baryon chiral perturbation theory results for the nucleon polarisabilities that describe the different regimes of nucleon Compton scattering --- real, virtual, and doubly virtual. We stress the importance of the empirical verification of the theory in the context of the calculation of the inelastic nucleon structure corrections, such as the two-photon exchange contributions. We also discuss the recently obtained constraints that relate the different regimes of nucleon Compton scattering and can provide additional information on the nucleon structure.
hep-phnucl-exnucl-thPoS(2019)·1 citation
13*
Inclusive diffractive heavy quarkonium photoproduction in pp, pA and AA collisions
Yi Yang🇨🇳 · Shaohong Cai🇨🇳 · Yanbing Cai🇨🇳 · Wenchang Xiang🇨🇳
The inclusive $J /Ψ$ production by direct and resolved photoproduction in the $γ$ p scattering is calculated based on the nonrelativistic quantum chromodynamics (NRQCD) factorization formalism, which is in good agreement with the experimental data of total cross section distribution of heavy quarkonium production at HERA. Then we extend the formalism including the direct and resolved photoproduction processes to resolved pomeron model to study the heavy quarkonium photoproduction at the LHC energies. We present the predictions of rapidity and transverse momentum distributions of the inclusive diffractive $J /Ψ$ , $Ψ (2 S)$ and $Υ$ photoproduction in pp, pPb and PbPb collisions at the LHC energies. Our numerical results indicate that the resolved photoproduction processes play an important role in the heavy quarkonium production. Especially for pp collisions, the contribution of resolved photoproduction processes is the largest, which can reach to $28%$ , $13%$ and $44%$ for the rapidity distributions of $J /Ψ$ , $Ψ (2 S)$ and $Υ$ inclusive diffractive photoproduction, respectively.
hep-phNPA(2019)·6 citations
14*
Investigation of $J / ψ \to γ π^{0} η (π^{+} π^{-}, π^{0} π^{0})$ radiative decays including final-state interactions
C. W. Xiao🇨🇳 · U.-G. Meißner🇩🇪 · J. A. Oller🇪🇸
We revisit the coupled channel $K K ˉ$ interactions and dynamically generate the resonances $f_{0} (980)$ and $a_{0} (980)$ within both the isospin and the physical bases. The $f_{0} (980) - a_{0} (980)$ mixing effects are generated in the scattering amplitudes of the coupled channels with the physical basis, which exploits the important role of the $K K ˉ$ channel in the dynamical nature of these resonances. With the scattering amplitudes obtained, we investigate the $f_{0} (980)$ and $a_{0} (980)$ contributions to the $J / ψ \to γ η π^{0}$ , $J / ψ \to γ π^{+} π^{-}$ and $J / ψ \to γ π^{0} π^{0}$ radiative decays through the final-state interactions. We obtain the corresponding branching fractions $B r (J / ψ \to γ a_{0} (980) \to γ η π^{0}) = (0.47 \pm 0.05) \times 1 0^{- 7}$ , $B r (J / ψ \to γ f_{0} (980) \to γ π^{+} π^{-}) = 0.37 \times 1 0^{- 7} - 1.98 \times 1 0^{- 6}$ , $B r (J / ψ \to γ f_{0} (980) \to γ π^{0} π^{0}) = 0.18 \times 1 0^{- 7} - 9.92 \times 1 0^{- 7}$ , and predict $B r (J / ψ \to γ a_{0} (980)) = 1.72 \times 1 0^{- 8} - 3.07 \times 1 0^{- 7}$ and $B r (J / ψ \to γ f_{0} (980)) = 1.86 \times 1 0^{- 8} - 1.89 \times 1 0^{- 5}$ . These fractions are within the upper limits of the experimental measurements.
hep-phEPJA(2020)·17 citations
15*
New $A_{4}$ lepton flavor model from $S_{4}$ modular symmetry
Tatsuo Kobayashi🇯🇵 · Yusuke Shimizu🇯🇵 · Kenta Takagi🇯🇵 · Morimitsu Tanimoto🇯🇵 · Takuya H. Tatsuishi🇯🇵
We study a flavor model with $A_{4}$ symmetry which originates from $S_{4}$ modular group. In $S_{4}$ symmetry, $Z_{2}$ subgroup can be anomalous, and then $S_{4}$ can be violated to $A_{4}$ . Starting with a $S_{4}$ symmetric Lagrangian at the tree level, the Lagrangian at the quantum level has only $A_{4}$ symmetry when $Z_{2}$ in $S_{4}$ is anomalous. We obtain modular forms of two singlets and a triplet representations of $A_{4}$ by decomposing $S_{4}$ modular forms into $A_{4}$ representations. We propose a new $A_{4}$ flavor model of leptons by using those $A_{4}$ modular forms. We succeed in constructing a viable neutrino mass matrix through the Weinberg operator for both normal hierarchy (NH) and inverted hierarchy (IH) of neutrino masses. Our predictions of the CP violating Dirac phase $δ_{C P}$ and the mixing $sin^{2} θ_{23}$ depend on the sum of neutrino masses for NH.
hep-phJHEP(2020)·128 citations
16*
Exploring the effect of Lorentz invariance violation with the currently running long-baseline experiments
Rudra Majhi🇮🇳 · Soumya C · Rukmani Mohanta🇮🇳
Neutrinos are the fundamental particles, blind to all kind of interactions except the weak and gravitational. Hence, they can propagate very long distances without any deviation. This characteristic property can thus provide an ideal platform to investigate Planck suppressed physics through their long distance propagation. In this work, we intend to investigate CPT violation through Lorentz invariance violation (LIV) in the long-baseline accelerator based neutrino experiments. Considering the simplest four-dimensional Lorentz violating parameters, for the first time, we obtain the sensitivity limits on the LIV parameters from the currently running long-baseline experiments T2K and NO $ν$ A. In addition to this, we show their effects on mass hierarchy and CP violation sensitivities by considering NO $ν$ A as a case study. We find that the sensitivity limits on LIV parameters obtained from T2K are much weaker than that of NO $ν$ A and the synergy of T2K and NO $ν$ A can improve these sensitivities. All these limits are slightly weaker ( $2 σ$ level) compared to the values extracted from Super-Kamiokande experiment with atmospheric neutrinos. Moreover, we observe that the mass hierarchy and CPV sensitivities are either enhanced or deteriorated significantly in the presence of LIV as these sensitivities crucially depend on the new CP-violating phases. We also present the correlation between $sin^{2} θ_{23}$ and the LIV parameter $∣ a_{α β} ∣$ , as well as $δ_{C P}$ and $∣ a_{α β} ∣$ .
hep-phEPJC(2020)·24 citations
17*
$A_{4}$ flavor symmetric model in SUSY SU(5) GUT
Yu Muramatsu🇨🇳 · Hideaki Okane🇯🇵 · Yusuke Shimizu🇯🇵 · Kenta Takagi🇯🇵
We propose a model with $A_{4}$ flavor symmetry for leptons and quarks in the framework of supersymmetric SU(5) grand unified theory (GUT). The running masses of quarks and charged leptons at GUT scale ( $\sim 1 0^{16}$ GeV) are realized by the adjoint 24-dimensional Higgs multiplet and additional gauge singlet scalar fields including flavons. In this paper, we focus on a result of the quark and charged lepton masses and quark mixing since our present model is known to reproduce recent experimental results of the neutrino mass and oscillation. Those results are showed numerically.
hep-ph0 citations
18*
Unified Interpretation of Scalegenesis in Conformally Extended Standard Models
Hiroyuki Ishida🇯🇵 · Shinya Matsuzaki🇨🇳 · Ruiwen Ouyang🇪🇪
We present a universal interpretation for a class of conformal extended standard models including Higgs portal interactions realized in low-energy effective theories. The scale generation mechanism in this class (scalegenesis) arises along the (nearly) conformal/flat direction for the scale symmetry breaking, where the electroweak-symmetry breaking structure is achieved in a similar way to the standard model's. A dynamical origin for the Higgs portal coupling can provide the discriminator for the low-energy ``universality class'', to be probed in forthcoming collider experiments.
hep-phhep-thCPC(2020)·11 citations
19*
QCD corrections to inclusive heavy hadron weak decays at $Λ_{QCD}^{3} / m_{Q}^{3}$
Thomas Mannel🇩🇪 · Alexei A. Pivovarov🇩🇪
We present an analytical calculation of the $α_{s}$ corrections for the coefficient of $ρ_{D} / m_{Q}^{3}$ term in the heavy quark expansion for the inclusive semileptonic decays of heavy hadrons, such as $B \to X_{c} ℓ ν ˉ$ . The full dependence of the coefficient on the final-state quark mass is taken into account. Our result leads to further improvement of the theoretical predictions for the precision determination of CKM matrix element $∣ V_{c b} ∣$ .
hep-phPRD(2019)·43 citations
20*
Discerning the two $K_{1} (1270)$ poles in $D^{0} \to π^{+} V P$ decay
G. Y. Wang🇪🇸 · L. Roca🇪🇸 · E. Oset🇪🇸
Within the chiral unitary approach, the axial-vector resonance $K_{1} (1270)$ has been predicted to manifest a two-pole nature. The lowest pole has a mass of 1195 Mev and a width of 246 Mev and couples mostly to $K^{*} π$ , and the highest pole has a mass of 1284 Mev and a width of 146 Mev and couples mostly to $ρ K$ . We analyze theoretically how this double-pole structure can show up in the $D^{0} \to π^{+} V P$ decays by looking at the vector-pseudoscalar ( $V P$ ) invariant mass distribution for different $V P$ channels, exploiting the fact that each pole couples differently to different $V P$ pairs. We find that the final $K ˉ^{*} π$ and $ρ K ˉ$ channels are sensible to the different poles of the $K_{1} (1270)$ resonance and hence are suitable reactions to analyze experimentally the double pole nature of this resonance.
hep-phPRD(2019)·19 citations
21*
Higgsino Dark Matter in a Non-Standard History of the Universe
Chengcheng Han🇰🇷
A light higgsino is strongly favored by the naturalness, while as a dark matter candidate it is usually under-abundant. We consider the higgsino production in a non-standard history of the universe, caused by a scalar field with an initially displaced vacuum. We find that given a proper reheating temperature induced by the scalar decay, a light higgsino could provide the correct dark matter relic abundance. On the other hand, a sub-TeV higgsino dark matter, once observed, would be a strong hint of the non-standard thermal history of the universe.
hep-phPLB(2019)·19 citations
22*
Resolving the $ϕ_{2}$ ( $α$ ) ambiguity in $B^{0} \to a_{1}^{\pm} π^{\mp}$
J. Dalseno🇪🇸
I propose an alternative method for measuring the $C P$ violating phase $ϕ_{2}$ ( $α$ ) without ambiguity in an extended SU(3) flavour symmetry analysis, which can ultimately be achieved by exploiting interference effects between $B \to A P$ and $B \to V V$ decay channels, where $A, V, P$ indicates an axial-vector, vector and pseudo-scalar meson, respectively. Under certain assumptions on the relevant decays based on current experimental results and minimal theoretical input, I demonstrate with an idealised amplitude model that a programme to extract a single solution for $ϕ_{2}$ in the range [0, $π$ ], with the added possibility to simultaneously constrain non-factorisable SU(3)-breaking effects, could be executed to similar precision using Run 3 data at LHCb and the final Belle II sample.
hep-phJHEP(2019)·8 citations
23*
On elastic scattering amplitude of planar charged fermions in a constant magnetic field
V.R. Khalilov🇷🇺
The elastic scattering amplitude (ESA) is obtained in the one-loop approximation of the 2+1 dimensional quantum electrodynamics (QED $_{2 + 1}$ ) for planar charged fermions in an external constant magnetic field. We obtain the elastic scattering amplitude in the corresponding massive theory and then discuss and calculate the massless limit of ESA. The imaginary part of ESA are related to the total probability of photons emission by charged fermions in the considered magnetic field. Simple analytical formulas are obtained when planar charged fermions in initial states occupy high excited Landau levels.
hep-phInt.J.Mod.Phys.A(2019)·5 citations
24*
Opportunities for spin physics at EIC
Daniël Boer🇳🇱
This is a brief overview of the spin physics opportunities at a high energy, high luminosity, polarized Electron-Ion Collider (EIC). It covers measurements of electroweak polarized structure functions, quark and gluon PDFs, TMDs, GPDs and GTMDs. Exploiting the many possible final states allows to probe various spin effects. Open and bound heavy quark production can be used to probe gluon TMDs, but also color-octet NRQCD long distance matrix elements. Spin-dependent fragmentation functions can be used too, but are also interesting in themselves. Especially for studies of the small- $x$ and the high- $Q^{2}$ spin structure the EIC will be essential.
hep-phhep-exPoS(2019)·1 citation
25*
Towards constraining Dark Matter at the LHC: Higher order QCD predictions for $t t ˉ + Z (Z \to ν_{ℓ} ν ˉ_{ℓ})$
G. Bevilacqua🇭🇺 · H. B. Hartanto🇬🇧 · M. Kraus🇩🇪 · T. Weber🇩🇪 · M. Worek🇩🇪
Triggered by ongoing dark matter searches in the top quark sector at the Large Hadron Collider we report on the calculation of the next-to-leading order QCD corrections to the Standard Model process $pp \to t t ˉ + Z (\to ν_{ℓ} ν ˉ_{ℓ})$ . This calculation is based on matrix elements for $e^{+} ν_{e} μ^{-} ν ˉ_{μ} b b ˉ ν_{τ} ν ˉ_{τ}$ production and includes all non-resonant diagrams, interferences, and off-shell effects of the top quarks. Non-resonant and off-shell effects due to the finite $W$ -boson width are also consistently taken into account. As it is common for such studies, we present results for both integrated and differential cross sections for a few renormalisation and factorisation scale choices and three different parton distribution functions. Already with the fairly inclusive cut selection and independently of the scale choice and the parton distribution function non-flat differential $K$ -factors are obtained for $p_{T}^{mi ss}, Δ ϕ_{ℓℓ}, Δ y_{ℓℓ}, cos θ_{ℓℓ}, H_{T}, H_{T}^{'}$ observables that are relevant for new physics searches. Good theoretical control over the Standard Model background is a fundamental prerequisite for a correct interpretation of possible signals of new physics that may arise in this channel. Thus, these observables need to be carefully reexamined in the presence of more exclusive cuts before any realistic strategies for the detection of new physics signal can be further developed.
hep-phhep-exJHEP(2019)·42 citations
26*
Double Polarization Observables in Pentaquark Photoproduction
JPAC Collaboration: Daniel Winney🇺🇸 · Cristiano Fanelli🇺🇸 · Alessandro Pilloni🇮🇹 · Astrid N. Hiller Blin🇩🇪 · Cesar Fernandez-Ramirez🇲🇽 · Miguel Albaladejo🇺🇸 · Vincent Mathieu🇪🇸 · Victor I. Mokeev🇺🇸 · Adam P. Szczepaniak🇺🇸
We investigate the properties of the hidden charm pentaquark-like resonances first observed by LHCb in 2015, by measuring the polarization transfer KLL between the incident photon and the outgoing proton in the exclusive photoproduction of J/psi near threshold. We present a first estimate of the sensitivity of this observable to the pentaquark photocouplings and hadronic branching ratios, and extend our predictions to the case of initial state helicity correlation ALL, using a polarized target. These results serve as a benchmark for the SBS experiment at Jefferson Lab, which proposes to measure for the first time the helicity correlations ALL and KLL in J/psi exclusive photoproduction, in order to determine the pentaquark photocouplings and branching ratios.
hep-phhep-exnucl-exPRD(2019)·45 citations
27*
TMD parton distributions from parton showers
Melanie Schmitz🇩🇪 · Francesco Hautmann🇧🇪 · Hannes Jung🇩🇪 · Sara Taheri Monfared🇩🇪
We present the determination of Transverse Momentum Dependent (TMD) parton distributions from Monte Carlo parton showers. We investigate the effective TMD distributions obtained from the PYTHIA8 and HERWIG6 parton showers and compare them to the TMD distributions determined within the Parton Branching method.
hep-phPoS(2019)·1 citation
28*
Leptogenesis with testable Dirac neutrino mass generation
Pei-Hong Gu🇨🇳
A TeV-scale Higgs doublet can acquire a tiny vacuum expectation value via its small mixing with the standard model Higgs doublet. Ones then can realize a testable Dirac neutrino mass generation through the sizable Yukawa couplings among this new Higgs doublet, several right-handed neutrinos and the standard model lepton doublets. We show the small mixing between the two Higgs doublets can come from certain interactions for generating the cosmic baryon asymmetry.
hep-phPLB(2020)·16 citations
29*
Common origin of inverse seesaw and baryon asymmetry
Pei-Hong Gu🇨🇳
In the inverse seesaw scenario, several fermion singlets have a small Majorana mass term. We show such Majorana masses can be suppressed by some heavy fermion and/or Higgs singlets after a global symmetry is spontaneously broken. These interactions can also accommodate a leptogenesis mechanism to explain the cosmic baryon asymmetry.
hep-phPLB(2020)·5 citations
30*
QCD Resummation in Hard Diffractive Dijet Production at the Electron-Ion Collider
Yoshitaka Hatta🇺🇸 · Niklas Mueller🇺🇸 · Takahiro Ueda🇯🇵 · Feng Yuan🇺🇸
Diffractive dijet production at the electron-ion collider (EIC) has been proposed to study the gluon Wigner distribution at small- $x$ . We investigate the soft gluon radiation associated with the final state jets and an all order resummation formula is derived. We show that the soft gluon resummation plays an important role to describe E791 data on $π$ -induced diffractive dijet production at Fermilab. Predictions for the EIC are presented, and we emphasize that the soft gluon resummation is an important aspect to explore the nucleon/nucleus tomography through these processes.
hep-phnucl-thPLB(2020)·30 citations
31*
Lepton angular distribution of Z boson production and jet discrimination
Jen-Chieh Peng🇺🇸 · Wen-Chen Chang🇹🇼 · Randall Evan McClellan🇺🇸 · Oleg Teryaev🇷🇺
High precision data of lepton angular distributions in inclusive $Z$ boson production, reported by the CMS and ATLAS Collaborations, showed pronounced transverse momentum ( $q_{T}$ ) dependencies of the $A_{0}$ and $A_{2}$ coefficients. Violation of the Lam-Tung relation, $A_{0} = A_{2}$ , was also found. An intuitive understanding of these results can be obtained from a geometric approach. We predict that $A_{0}$ and $A_{2}$ for $Z$ plus single gluon-jet events are very different from that of $Z$ plus single quark-jet events, allowing a new experimental tool for checking various algorithms which attempt to discriminate quark jets from gluon jets. We also predict that the Lam-Tung relation would be more severely violated for the $Z$ plus multiple-jet data than what has been observed so far for inclusive $Z$ production data. These predictions can be readily tested using existing LHC data.
hep-phPLB(2019)·4 citations
32*
Fundamental physics with high-energy cosmic neutrinos today and in the future
Carlos A. Argüelles (MIT)🇺🇸 · Mauricio Bustamante (Bohr Inst. & DARK Cosmology Ctr.)🇩🇰 · Ali Kheirandish (Wisconsin U., Madison)🇺🇸 · Sergio Palomares-Ruiz (Valencia U., IFIC)🇪🇸 · Jordi Salvado (Barcelona U., ECM & ICC, Barcelona U.)🇪🇸 · Aaron C. Vincent (Queen's U., Kingston & Perimeter Inst. Theor. Phys.)🇨🇦
The astrophysical neutrinos discovered by IceCube have the highest detected neutrino energies --- from TeV to PeV --- and likely travel the longest distances --- up to a few Gpc, the size of the observable Universe. These features make them naturally attractive probes of fundamental particle-physics properties, possibly tiny in size, at energy scales unreachable by any other means. The decades before the IceCube discovery saw many proposals of particle-physics studies in this direction. Today, those proposals have become a reality, in spite of astrophysical unknowns. We will showcase examples of doing fundamental neutrino physics at these scales, including some of the most stringent tests of physics beyond the Standard Model. In the future, larger neutrino energies --- up to tens of EeV --- could be observed with larger detectors and further our reach.
↳ astro-ph.HEhep-exhep-phhep-thPoS(2020)·51 citations
33*
Calculating the EoS of the dense quark-gluon plasma using the Complex Langevin equation
Dénes Sexty🇩🇪
The pressure and energy density of the quark-gluon plasma at finite baryon chemical potential are calculated using the Complex Langevin equation. The stout smearing procedure is generalized for the SL(3, $C$ ) manifold allowing the usage of an improved action in the Complex Langevin setup. Four degenerate flavors of staggered quarks with $m_{π} = 500 - 700$ MeV are used with a tree-level Symanzik improved gauge action on $1 6^{3} \times 8$ lattices. Results are compared to the Taylor expansion and good agreement is found for small chemical potentials.
↳ hep-lathep-phPRD(2019)·46 citations
34*
Measurement of the azimuthal modulations of hadrons in unpolarised SIDIS
Jan Matousek (on behalf of the COMPASS Collaboration)🇮🇹
In 2016 and 2017 COMPASS has collected a considerable amount of deep inelastic scattering events with a 160 GeV/c muon beam and a liquid hydrogen target. An analysis of 4 % of these data has allowed to extract preliminary results on the amplitudes of three azimuthal modulations, $A_{U U}^{c o s ϕ_{h}}$ , $A_{U U}^{c o s 2 ϕ_{h}}$ and $A_{LU}^{s i n ϕ_{h}}$ . The first two are particularly important since they carry information on the intrinsic transverse momentum $k_{T}$ of the quarks and on the correlations between the quark spin and $k_{T}$ , expressed by the Boer-Mulders TMD PDFs. They show strong kinematic dependence as a function of the Bjorken variable $x$ , of the fraction of virtual photon energy carried by the hadron $z$ and of the component $P_{h T}$ of the hadron momentum orthogonal to the virtual photon direction, thus confirming the results of previous measurements. Also, as was recently shown by COMPASS, hadrons coming from decay of diffractively produced vector mesons give significant contribution to the amplitudes in certain kinematic regions, explaining in part the kinematic dependencies and helping the interpretation of the measurements. The effect on the published COMPASS $^{6}$ LiD data is discussed.
↳ hep-exhep-phPoS(2019)·3 citations
35*
Eternal Inflation, Entropy Bounds and the Swampland
Ziwei Wang🇨🇦 · Robert Brandenberger🇨🇦 · Lavinia Heisenberg (McGill University and ETH Zuerich)🇨🇭
It has been suggested that low energy effective field theories should satisfy given conditions in order to be successfully embedded into string theory. In the case of a single canonically normalized scalar field this translates into conditions on its potential and the derivatives thereof. In this Letter we revisit stochastic models of small field inflation and study the compatibility of the swampland constraints with entropy considerations. We show that stochastic inflation either violates entropy bounds or the swampland criterium on the slope of the scalar field potential. Furthermore, we illustrate that such models are faced with a graceful exit problem: any patch of space which exits the region of eternal inflation is either not large enough to explain the isotropy of the cosmic microwave background, or has a spectrum of fluctuations with an unacceptably large red tilt.
↳ hep-thastro-ph.COgr-qchep-phEPJC(2020)·42 citations
36*
From Minkowski to de Sitter in Multifield No-Scale Models
John Ellis🇬🇧 · Balakrishnan Nagaraj🇺🇸 · Dimitri V. Nanopoulos🇺🇸 · Keith A. Olive🇺🇸 · Sarunas Verner🇺🇸
We show the uniqueness of superpotentials leading to Minkowski vacua of single-field no-scale supergravity models, and the construction of dS/AdS solutions using pairs of these single-field Minkowski superpotentials. We then extend the construction to two- and multifield no-scale supergravity models, providing also a geometrical interpretation. We also consider scenarios with additional twisted or untwisted moduli fields, and discuss how inflationary models can be constructed in this framework.
↳ hep-thgr-qchep-phJHEP(2019)·18 citations
37*
Polarization in $Ξ_{c}^{0}$ decays
Tong-Zhu Han · Rong-Gang Ping · Tao Luo
Measurements on the weak decay asymmetry parameters of charmed baryon, say $Ξ_{c}$ , provide more information on the $W$ -emission and $W$ -exchange mechanisms controlled by the strong and weak interactions. Taking advantage of the spin polarization in the charmed baryon decays, we investigate the possibility to measure the weak decay asymmetry parameters in the $e^{+} e^{-} \to Ξ_{c}^{0} Ξ ˉ_{c}^{0}$ process. We analyze the transverse polarization spontaneously produced in this process and spin transfer in the subsequent $Ξ_{c}$ decays. The sensitivity to measure the asymmetry parameters are estimated for the decay $Ξ_{c} \to Ξ π$ .
↳ hep-exhep-phCPC(2020)·10 citations
38*
Determination of the absolute branching fractions of X(3872) decays
Chunhua Li🇨🇳 · Chang-Zheng Yuan🇨🇳
We report the first determination of the absolute branching fractions of the X(3872) decays by globally analyzing the measurements provided by the Belle, BaBar, BESIII, and LHCb experiments. The branching fractions of X(3872) to pi^+pi^- J/psi and D*0D0bar+c.c. are found to be (4.1^{+1.9}_{-1.1})% and (52.4^{+25.3}_{-14.3})%, respectively. The branching fractions of the decays X(3872) to gamma J/psi, gamma psi', omega J/psi, and pi^0 chi_{c1} are also determined. The global fit implies that the fraction of X(3872) decays which are not observed in experiments is (31.9_{-31.5}^{+18.1})%, which indicates that there is still a lot of room for searching for new decay modes of the X(3872). With the branching fraction, we determine the production cross section of e+e- to gamma X(3872) at center-of-mass energy 4.226 GeV.
↳ hep-exhep-phPRD(2019)·47 citations
39*
Linear growth index of matter perturbations in Rastall gravity
Wompherdeiki Khyllep🇮🇳 · Jibitesh Dutta🇮🇳
Rastall gravity theory shows notable features consistent with physical observations in comparison to the standard Einstein theory. Recently, there has been a debate about the equivalence of Rastall gravity and general relativity. Motivated by this open issue, in the present work, we attempt to shed some light on this debate by analyzing the evolution of the Rastall based cosmological model at the background as well as perturbation level. Employing the dynamical system techniques, we found that at late times, the dynamics of the model resembles the $Λ$ CDM model at the background level irrespective of the choice of Rastall's parameter. However, at the perturbation level, we found that the evolution of the growth index heavily depends on the Rastall's parameter and displays a significant deviation from the $Λ$ CDM model.
↳ gr-qchep-phPLB(2019)·41 citations
40*
Prompt, pre-equilibrium, and thermal photons in relativistic nuclear collisions
Akihiko Monnai🇯🇵
The direct photon emission model in relativistic nuclear colliders has been improved in recent years for reducing the discrepancy between theoretical estimations and experimental data and for understanding the properties of the QCD matter. In this study, the contribution of pre-equilibrium photons are investigated in addition to those of prompt and thermal photons in the framework of a relativistic hydrodynamic model. The numerical simulations at an LHC energy suggest that the pre-equilibrium photons may be relevant at intermediate transverse momentum near the saturation momentum scale, increasing particle spectra and reducing elliptic flow of direct photons.
↳ nucl-thhep-phnucl-exJ.Phys.G(2020)·29 citations
41*
Energy-conservation constraints on cosmic string loop production and distribution functions
Jose J. Blanco-Pillado🇪🇸 · Ken D. Olum🇺🇸 · Jeremy M. Wachter🇪🇸
A network of cosmic strings would lead to gravitational waves which may be detected by pulsar timing or future interferometers. The details of the gravitational wave signal depend on the distribution of cosmic string loops, which are produced by intercommutations from the scaling network of long strings. We analyze the limits imposed by energy conservation, i.e., by the fact that the total amount of string flowing into loops cannot exceed the amount leaving the long strings. We show that some recent suggestions for the cosmic string loop production rate and distribution are ruled out by these limits. As a result, gravitational waves based on such suggestions, in particular "model 3" used in LIGO data analysis, are not to be expected.
↳ astro-ph.COgr-qchep-phPRD(2019)·35 citations
42*
Dependence of the static quark free energy on $μ_{B}$ and the crossover temperature of $N_{f} = 2 + 1$ QCD
Massimo D'Elia🇮🇹 · Francesco Negro🇮🇹 · Andrea Rucci🇮🇹 · Francesco Sanfilippo🇮🇹
We study the dependence of the static quark free energy on the baryon chemical potential for $N_{f} = 2 + 1$ QCD with physical quark masses, in a range of temperature spanning from 120~MeV up to 1~GeV and adopting a stout staggered discretization with two different values of the Euclidean temporal extension, $N_{t} = 6$ and $N_{t} = 8$ . In order to deal with the sign problem, we exploit both Taylor expansion and analytic continuation, obtaining consistent results. We show that the dependence of the free energy on $μ_{B}$ is sensitive to the location of the chiral crossover, in particular the $μ_{B}$ -susceptibility, i.e. the linear term in $μ_{B}^{2}$ in the Taylor expansion of the free energy, has a peak around 150 MeV. We also discuss the behavior expected in the high temperature regime based on perturbation theory, and obtain a good quantitative agreement with numerical results.
↳ hep-lathep-phPRD(2019)·12 citations
43*
Light composite fermions from holography
Raimond Abt🇩🇪 · Johanna Erdmenger🇩🇪 · Nick Evans🇬🇧 · Konstantinos S. Rigatos🇬🇧
Motivated by Beyond the Standard Model theories of composite fermions or top partners, we propose a holographic mechanism that generates light baryonic states in a strongly coupled gauge theory. The starting point are the fermionic fluctuations of massive probe branes embedded into AdS $_{5} \times S^{5}$ . We first consider the D3/probe D7-brane system. We derive in detail the fermionic fluctuation equations and show the supersymmetric degeneracy of the mesinos with the mesons. Here we view the fermionic mesinos as potential realizations of composite fermions or top partners. We then add higher dimension operators and study their impact on the mesino spectrum. In particular we show that the ground state mesino mass can be pushed to an arbitrarily light value by a suitable choice of the coupling of the higher dimension operator, $g$ . No matter the value of $g$ , the masses of higher excited states never fall below the mass of the ground state at $g = 0$ . We also present similar results for the supersymmetric D3/D3 and D3/D5 systems.
↳ hep-thhep-phJHEP(2019)·30 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.