اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدOn resonance search in dijet events at the LHC
56
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
New strategy for resonance search in dijet events at the LHC is discussed. The main distribution used for a bump search is the dijet invariant mass distribution with appropriated cuts. The crucial cut, which is applied to maximize signal significance, is on (pseudo)rapidity difference between the two jets. This is due to the exponential growing of the QCD background contribution with this variable. Usually it is assumed that signal from almost all exotic models populates the central dijet rapidity region y_{1,2} ~ 0 and |y_1-y_2| ~ 0. By contrast, the excited bosons do not contribute into this region, but produce an excess of dijet events over the almost flat QCD background in chi = exp|y_1-y_2| away from this region. Therefore, different sets of cuts should be applied for new physics search depending on the searched resonance properties. In order to confirm the bump and reveal the resonance nature various angular distributions should be used in addition. In particular, for the excited bosons the special choice of parameters could lead to a dip in the centrality ratio distribution over the dijet invariant mass instead of a bump, expected in the most exotic models.
قيم البحث
اقرأ أيضاً
We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that the fundam
ental string mass scale is in the TeV range and the theory is weakly coupled, we discuss possible signals of string physics at the Large Hadron Collider (LHC). In such D-brane constructions, the dominant contributions to full-fledged string amplitudes for all the common QCD parton subprocesses leading to dijets are completely independent of the details of compactification, and can be evaluated in a parameter-free manner. We make use of these amplitudes evaluated near the first resonant pole to determine the discovery potential of LHC for the first Regge excitations of the quark and gluon. Remarkably, the reach of LHC after a few years of running can be as high as 6.8 TeV. Even after the first 100 pb^{-1} of integrated luminosity, string scales as high as 4.0 TeV can be discovered. For string scales as high as 5.0 TeV, observations of resonant structures in pp to {rm direct} gamma + jet can provide interesting corroboration for string physics at the TeV-scale.
We present a next-to-leading order QCD calculation of inclusive dijet photoproduction in ultraperipheral Pb-Pb collisions at the LHC and show that the results agree very well with various kinematic distributions measured by the ATLAS collaboration. T
he effect of including these data in nCTEQ or EPPS16 nuclear parton density functions (nPDFs) is then studied using the Bayesian reweighting technique. For an assumed total error of 5% on the final data, its inclusion would lead to a significant reduction of the nPDF uncertainties of up to a factor of two at small values of the parton momentum fraction. As an outlook, we discuss future analyes of diffractive nPDFs, which are so far completely unknown.
Using QCD calculations of the cross section of inclusive dijet photoproduction in Pb-Pb ultraperipheral collisions in the LHC kinematics as pseudo-data, we study the effect of including these data using the Bayesian reweighting technique on nCTEQ15,
nCTEQ15np, and EPPS16 nuclear parton distribution functions (nPDFs). We find that, depending on the assumed error of the pseudo-data, it leads to a significant reduction of the nPDF uncertainties at small values of the momentum fraction $x_A$. Taking the error to be 5%, the uncertainty of nCTEQ15 and nCTEQ15np nPDFs reduces approximately by a factor of two at $x_A=10^{-3}$. At the same time, the reweighting effect on EPPS16 nPDFs is much smaller due to the higher value of the tolerance and a more flexible parametrization form.
We analyze the structure of the high multiplicity events observed by the CMS collaboration at the LHC. We argue that the bulk of the observed correlations is due to the production of a pair of jets with p_t > 15 GeV/c. We also suggest that high multi
plicity events are due to a combination of three effects: high underlying multiplicity for collisions at small impact parameters, upward fluctuations of the gluon density in the colliding protons, and production of hadrons in the fragmentation of dijets. The data analysis is suggested which may clarify the underlying dynamics of the high multiplicity events and probe fluctuations of the gluon field as a function of x.
We calculate the cross section of inclusive dijet photoproduction in ultraperipheral collisions (UPCs) of heavy ions at the CERN Large Hadron Collider using next-to-leading order perturbative QCD and demonstrate that it provides a good description of
the ATLAS data. We study the role of this data in constraining nuclear parton distribution functions (nPDFs) using the Bayesian reweighting technique and find that it can reduce current uncertainties of nPDFs at small $x$ by a factor of 2. We also make predictions for diffractive dijet photoproduction in UPCs and examine its potential to shed light on the disputed mechanism of QCD factorization breaking in diffraction.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
