title: ÐÐµÑÐ¾Ð´Ñ ÑÑÐµÑÐ° Ð´ÐµÑÐµÐºÑÐ¾ÑÐ½ÑÑ ÑÑÑÐµÐºÑÐ¾Ð² Ð¿ÑÐ¸ Ð¸ÑÑÐ»ÐµÐ´Ð¾Ð²Ð°Ð½Ð¸Ð¸ ÑÐ¿Ð¸Ð½Ð¾Ð²ÑÑ ÐºÐ¾ÑÑÐµÐ»ÑÑÐ¸Ð¹ Ð² ÑÐ¾Ð±ÑÑÐ¸ÑÑ Ñ Ð¿Ð°ÑÐ½ÑÐ¼ ÑÐ¾Ð¶Ð´ÐµÐ½Ð¸ÐµÐ¼ t-ÐºÐ²Ð°ÑÐºÐ° Ð¸ t-Ð°Ð½ÑÐ¸ÐºÐ²Ð°ÑÐºÐ° Ð² ÑÐºÑÐ¿ÐµÑÐ¸Ð¼ÐµÐ½ÑÐµ ATLAS
title: Ð²ÑÐ¿ÑÑÐºÐ½Ð°Ñ ÐºÐ²Ð°Ð»Ð¸ÑÐ¸ÐºÐ°ÑÐ¸Ð¾Ð½Ð½Ð°Ñ ÑÐ°Ð±Ð¾ÑÐ° Ð¼Ð°Ð³Ð¸ÑÑÑÐ°
titleType: Subtitle
title: Methods of accounting for detector effects in the study of spin correlations in events with the paired production of a t-quark and t-antiquark in ATLAS experiment
Creators: name: ÐÐ¾ÑÐµÐ²Ð°, ÐÐ»ÐµÑÑ
Publisher: name: Ð¡Ð°Ð½ÐºÑ-ÐÐµÑÐµÑÐ±ÑÑÐ³ÑÐºÐ¸Ð¹ Ð¿Ð¾Ð»Ð¸ÑÐµÑÐ½Ð¸ÑÐµÑÐºÐ¸Ð¹ ÑÐ½Ð¸Ð²ÐµÑÑÐ¸ÑÐµÑ ÐÐµÑÑÐ° ÐÐµÐ»Ð¸ÐºÐ¾Ð³Ð¾
Year: 2023
Subjects: Ð£ÑÐºÐ¾ÑÐ¸ÑÐµÐ»Ð¸ Ð·Ð°ÑÑÐ¶ÐµÐ½Ð½ÑÑ ÑÐ°ÑÑÐ¸Ñ
ÐÐ¾Ð»ÑÑÐ¾Ð¹ ÐÐ´ÑÐ¾Ð½Ð½ÑÐ¹ ÐÐ¾Ð»Ð»Ð°Ð¹Ð´ÐµÑ
ÑÐ¸Ð·Ð¸ÐºÐ° Ð²ÑÑÐ¾ÐºÐ¸Ñ ÑÐ½ÐµÑÐ³Ð¸Ð¹
ÑÑÐ°Ð½Ð´Ð°ÑÑÐ½Ð°Ñ Ð¼Ð¾Ð´ÐµÐ»Ñ
ÑÐ¾Ð¿-ÐºÐ²Ð°ÑÐº
ÑÐ¿Ð¸Ð½Ð¾Ð²Ð°Ñ Ð¼Ð°ÑÑÐ¸ÑÐ° Ð¿Ð»Ð¾ÑÐ½Ð¾ÑÑÐ¸
ÐºÐ²Ð°Ð½ÑÐ¾Ð²Ð°Ñ Ð·Ð°Ð¿ÑÑÐ°Ð½Ð½Ð¾ÑÑÑ
Ð³ÐµÐ½ÐµÑÐ°ÑÐ¾ÑÑ ÐÐ¾Ð½ÑÐµ-ÐÐ°ÑÐ»Ð¾
Ð´ÐµÑÐµÐºÑÐ¾ÑÐ½ÑÐµ ÑÑÑÐµÐºÑÑ
Ð¼ÐµÑÐ¾Ð´Ñ Ð¾Ð±ÑÐ°ÑÐ½Ð¾Ð¹ ÑÐ²ÐµÑÑÐºÐ¸
ÐºÐ°Ð»Ð¸Ð±ÑÐ¾Ð²Ð¾ÑÐ½Ð°Ñ ÐºÑÐ¸Ð²Ð°Ñ
Ð¼ÐµÑÐ¾Ð´ Ð¿ÐµÑÐµÐ²Ð·Ð²ÐµÑÐ¸Ð²Ð°Ð½Ð¸Ñ
ÑÐ¸ÑÑÐµÐ¼Ð°ÑÐ¸ÑÐµÑÐºÐ°Ñ Ð½ÐµÐ¾Ð¿ÑÐµÐ´ÐµÐ»ÐµÐ½Ð½Ð¾ÑÑÑ
ÑÐ¾Ð½ÐºÐ¾Ð·Ð°Ð·Ð¾ÑÐ½ÑÐµ ÐºÐ°Ð¼ÐµÑÑ
high energy physics
standard model
Large Hadron Collider
top quark
spin dencity matrix
quantum entanglement
Monte-Carlo generators
detector effects
calibration curve
reweighting method
Unfolding method
systematic uncertainty
thin gap chambers

description: ÐÐ°Ð½Ð½Ð°Ñ ÑÐ°Ð±Ð¾ÑÐ° Ð¿Ð¾ÑÐ²ÑÑÐµÐ½Ð° Ð¼ÐµÑÐ¾Ð´Ð¸ÑÐµÑÐºÐ¸Ð¼ Ð¸ÑÑÐ»ÐµÐ´Ð¾Ð²Ð°Ð½Ð¸ÑÐ¼, Ð½Ð°Ð¿ÑÐ°Ð²Ð»ÐµÐ½Ð½ÑÑ Ð½Ð° Ð°Ð½Ð°Ð»Ð¸Ð· ÑÐ¿Ð¸Ð½Ð¾Ð²ÑÑ ÐºÐ¾ÑÑÐµÐ»ÑÑÐ¸Ð¹ Ð¿Ð°Ñ t-ÐºÐ²Ð°ÑÐº Ð¸ t-Ð°Ð½ÑÐ¸ÐºÐ²Ð°ÑÐº, Ð° ÑÐ°ÐºÐ¶Ðµ Ð¸Ð·ÑÑÐµÐ½Ð¸Ñ Ð¼ÐµÑÐ¾Ð´Ð¾Ð² ÑÑÐµÑÐ° Ð´ÐµÑÐµÐºÑÐ¾ÑÐ½ÑÑ ÑÑÑÐµÐºÑÐ¾Ð². ÐÐ·ÑÑÐµÐ½Ð¸Ðµ ÑÐ¿Ð¸Ð½Ð¾Ð²ÑÑ ÐºÐ¾ÑÑÐµÐ»ÑÑÐ¸Ð¹ tt Ì-ÐºÐ²Ð°ÑÐºÐ¾Ð² Ð²Ð°Ð¶Ð½Ð¾ ÐºÐ°Ðº Ð´Ð»Ñ ÑÑÐ¾ÑÐ½ÐµÐ½Ð¸Ñ Ð¡ÑÐ°Ð½Ð´Ð°ÑÑÐ½Ð¾Ð¹ Ð¼Ð¾Ð´ÐµÐ»Ð¸, ÑÐ°Ðº Ð¸ Ð´Ð»Ñ Ð¿Ð¾Ð¸ÑÐºÐ¾Ð² ÑÐ¸Ð·Ð¸ÐºÐ¸ Ð·Ð° ÐµÐµ Ð¿ÑÐµÐ´ÐµÐ»Ð°Ð¼Ð¸. Ð£ÑÐµÑ Ð´ÐµÑÐµÐºÑÐ¾ÑÐ½ÑÑ ÑÑÑÐµÐºÑÐ¾Ð² Ð½ÐµÐ¾Ð±ÑÐ¾Ð´Ð¸Ð¼ Ð´Ð»Ñ Ð²Ð¾ÑÑÑÐ°Ð½Ð¾Ð²Ð»ÐµÐ½Ð¸Ñ Ð¸ÑÑÐ¸Ð½Ð½ÑÑ ÑÐ°ÑÐ¿ÑÐµÐ´ÐµÐ»ÐµÐ½Ð¸Ð¹, ÑÑÐ¾ Ð´Ð°ÐµÑ Ð²Ð¾Ð·Ð¼Ð¾Ð¶Ð½Ð¾ÑÑÑ ÑÑÐ°Ð²Ð½Ð¸Ð²Ð°ÑÑ Ð¸Ð·Ð¼ÐµÑÐµÐ½Ð¸Ñ Ñ ÑÐµÐ¾ÑÐµÑÐ¸ÑÐµÑÐºÐ¸Ð¼Ð¸ Ð¿ÑÐµÐ´ÑÐºÐ°Ð·Ð°Ð½Ð¸ÑÐ¼Ð¸. Ð¦ÐµÐ»ÑÐ¼Ð¸ ÑÐ°Ð±Ð¾ÑÑ ÑÐ²Ð»ÑÑÑÑÑ: Ð¿ÑÐ¾Ð²ÐµÑÐºÐ° Ð¾Ð´Ð½Ð¾Ð³Ð¾ Ð¸Ð· Ð¼ÐµÑÐ¾Ð´Ð¾Ð² ÑÑÐµÑÐ° Ð´ÐµÑÐµÐºÑÐ¾ÑÐ½ÑÑ ÑÑÑÐµÐºÑÐ¾Ð² - Ð¼ÐµÑÐ¾Ð´Ð° ÐºÐ°Ð»Ð¸Ð±ÑÐ¾Ð²Ð¾ÑÐ½Ð¾Ð¹ ÐºÑÐ¸Ð²Ð¾Ð¹, Ð° ÑÐ°ÐºÐ¶Ðµ Ð¾ÑÐµÐ½ÐºÐ° ÑÐ°Ð·Ð»Ð¸ÑÐ½ÑÑ ÑÐµÐ¾ÑÐµÑÐ¸ÑÐµÑÐºÐ¸Ñ Ð¸ÑÑÐ¾ÑÐ½Ð¸ÐºÐ¾Ð² ÑÐ¸ÑÑÐµÐ¼Ð°ÑÐ¸ÑÐµÑÐºÐ¸Ñ Ð½ÐµÐ¾Ð¿ÑÐµÐ´ÐµÐ»ÐµÐ½Ð½Ð¾ÑÑÐµÐ¹. Ð ÑÐµÐ·ÑÐ»ÑÑÐ°ÑÐµ ÑÐ°Ð±Ð¾ÑÑ Ð±ÑÐ»Ð¸ Ð²ÑÐ¿Ð¾Ð»Ð½ÐµÐ½Ñ Ð¸ÑÑÐ»ÐµÐ´Ð¾Ð²Ð°Ð½Ð¸Ñ ÑÐ¿Ð¸Ð½Ð¾Ð²ÑÑ ÑÐ²Ð¾Ð¹ÑÑÐ² t-ÐºÐ²Ð°ÑÐºÐ° Ñ Ð¿Ð¾Ð¼Ð¾ÑÑÑ ÐÐ¾Ð½ÑÐµ-ÐÐ°ÑÐ»Ð¾ Ð¼Ð¾Ð´ÐµÐ»Ð¸ÑÐ¾Ð²Ð°Ð½Ð¸Ñ. ÐÐ»Ñ Ð¼Ð¾Ð´ÐµÐ»Ð¸ÑÐ¾Ð²Ð°Ð½Ð¸Ñ ÑÐ¾Ð¶Ð´ÐµÐ½Ð¸Ñ Ð¿Ð°Ñ t-ÐºÐ²Ð°ÑÐº Ð¸ t-Ð°Ð½ÑÐ¸ÐºÐ²Ð°ÑÐº Ð¸ÑÐ¿Ð¾Ð»ÑÐ·Ð¾Ð²Ð°Ð»Ð¸ÑÑ ÑÐ°Ð·Ð»Ð¸ÑÐ½ÑÐµ ÐÐ¾Ð½ÑÐµ-ÐÐ°ÑÐ»Ð¾ Ð³ÐµÐ½ÐµÑÐ°ÑÐ¾ÑÑ. ÐÑÐ»Ð¸ Ð¿Ð¾ÑÑÑÐ¾ÐµÐ½Ñ ÑÐ°ÑÐ¿ÑÐµÐ´ÐµÐ»ÐµÐ½Ð¸Ñ Ð¿Ð¾ Ð¿ÐµÑÐµÐ¼ÐµÐ½Ð½Ð¾Ð¹ cosâ¡(Ï_ll ) (Ð³Ð´Ðµ Ï_ll â ÑÐ³Ð¾Ð» Ð¼ÐµÐ¶Ð´Ñ Ð´Ð²ÑÐ¼Ñ Ð»ÐµÐ¿ÑÐ¾Ð½Ð°Ð¼Ð¸ Ð² ÑÐ¾Ð¾ÑÐ²ÐµÑÑÑÐ²ÑÑÑÐ¸Ñ Ð¸Ð¼ ÑÐ¾Ð´Ð¸ÑÐµÐ»ÑÑÐºÐ¸Ñ t-ÐºÐ²Ð°ÑÐºÐ¾Ð²), Ð¿Ð¾ ÐºÐ¾ÑÐ¾ÑÐ¾Ð¹ Ð²ÑÑÐ¸ÑÐ»ÑÐ»ÑÑ ÐºÐ¾ÑÑÑÐ¸ÑÐ¸ÐµÐ½Ñ ÐºÐ¾ÑÑÐµÐ»ÑÑÐ¸Ð¸ D. ÐÐ»Ñ ÑÐ¾Ð³Ð¾, ÑÑÐ¾Ð±Ñ ÑÑÐµÑÑÑ Ð´ÐµÑÐµÐºÑÐ¾ÑÐ½ÑÐµ ÑÑÑÐµÐºÑÑ, Ð±ÑÐ»Ð¾ Ð¿ÑÐ¾Ð¸Ð·Ð²ÐµÐ´ÐµÐ½Ð¾ Ð¿ÐµÑÐµÐ²Ð·Ð²ÐµÑÐ¸Ð²Ð°Ð½Ð¸Ðµ ÑÐ°ÑÐ¿ÑÐµÐ´ÐµÐ»ÐµÐ½Ð¸Ð¹ Ð¿Ð¾ Ð¿ÐµÑÐµÐ¼ÐµÐ½Ð½Ð¾Ð¹Â  cosâ¡(Ï_ll ) Ð½Ð° âtruthâ ÑÑÐ¾Ð²Ð½Ðµ Ð² ÑÐ°Ð·Ð»Ð¸ÑÐ½ÑÑ ÑÐ¾ÑÐºÐ°Ñ: -60%, -40%, -20%, 0%. Ð ÑÐ°ÐºÐ¶Ðµ, Ð±ÑÐ»Ð° Ð¿ÑÐ¾Ð²ÐµÐ´ÐµÐ½Ð° Ð¾ÑÐµÐ½ÐºÐ° ÑÐ¸ÑÑÐµÐ¼Ð°ÑÐ¸ÑÐµÑÐºÐ¸Ñ Ð½ÐµÐ¾Ð¿ÑÐµÐ´ÐµÐ»ÐµÐ½Ð½Ð¾ÑÑÐµÐ¹ Ð¾Ñ ÑÐ°Ð·Ð»Ð¸ÑÐ½ÑÑ Ð¸ÑÑÐ¾ÑÐ½Ð¸ÐºÐ¾Ð²: cÐ¸ÑÑÐµÐ¼Ð°ÑÐ¸ÐºÐ¸ ÑÑÐ½ÐºÑÐ¸Ð¹ ÑÐ°ÑÐ¿ÑÐµÐ´ÐµÐ»ÐµÐ½Ð¸Ñ Ð¿Ð°ÑÑÐ¾Ð½Ð¾Ð² (Ð°Ð½Ð³Ð». Parton Distribution Function, PDF), ÑÐ¸ÑÑÐµÐ¼Ð°ÑÐ¸ÐºÐ¸ Ð¼Ð°ÑÑÑÐ°Ð±Ð¾Ð² Ð¿ÐµÑÐµÐ½Ð¾ÑÐ¼Ð¸ÑÐ¾Ð²ÐºÐ¸ (Î¼_R) Ð¸ ÑÐ°ÐºÑÐ¾ÑÐ¸Ð·Ð°ÑÐ¸Ð¸ (Î¼_F), Ð° ÑÐ°ÐºÐ¶Ðµ ÑÐ¸ÑÑÐµÐ¼Ð°ÑÐ¸ÐºÐ¸, ÑÐ²ÑÐ·Ð°Ð½Ð½Ð¾Ð¹ Ñ Ð¸Ð·Ð»ÑÑÐµÐ½Ð¸ÐµÐ¼ Ð² Ð½Ð°ÑÐ°Ð»ÑÐ½Ð¾Ð¼ ÑÐ¾ÑÑÐ¾ÑÐ½Ð¸Ð¸ (Ð°Ð½Ð³Ð». Initial State Radiation, ISR). ÐÑÐµÐ½ÐºÐ° ÑÐ¸ÑÑÐµÐ¼Ð°ÑÐ¸ÑÐµÑÐºÐ¾Ð¹ Ð½ÐµÐ¾Ð¿ÑÐµÐ´ÐµÐ»ÐµÐ½Ð½Ð¾ÑÑÐ¸ Ð¿ÑÐ¾Ð²Ð¾Ð´Ð¸Ð»Ð°ÑÑ Ð² ÐºÐ°Ð¶Ð´Ð¾Ð¹ ÑÐ¾ÑÐºÐµ Ð¿ÐµÑÐµÐ²Ð·Ð²ÐµÑÐ¸Ð²Ð°Ð½Ð¸Ñ. Ð ÑÐµÐ·ÑÐ»ÑÑÐ°ÑÐµ ÑÐµÐ³Ð¾ Ð±ÑÐ»Ð° Ð¿Ð¾Ð»ÑÑÐµÐ½Ð° Ð¾Ð±Ð»Ð°ÑÑÑ ÑÐ¸ÑÑÐµÐ¼Ð°ÑÐ¸ÑÐµÑÐºÐ¸Ñ Ð½ÐµÐ¾Ð¿ÑÐµÐ´ÐµÐ»ÐµÐ½Ð½Ð¾ÑÑÐµÐ¹ Ð´Ð»Ñ ÐºÐ°Ð¶Ð´Ð¾Ð¹ ÐºÐ°Ð»Ð¸Ð±ÑÐ¾Ð²Ð¾ÑÐ½Ð¾Ð¹ ÐºÑÐ¸Ð²Ð¾Ð¹. Ð ÐµÐ·ÑÐ»ÑÑÐ°ÑÑ Ð¿ÑÐ¾Ð²ÐµÐ´ÐµÐ½Ð½Ð¾Ð³Ð¾ Ð°Ð½Ð°Ð»Ð¸Ð·Ð° Ð¿Ð¾Ð·Ð²Ð¾Ð»ÑÑÑ ÑÐ´ÐµÐ»Ð°ÑÑ ÑÐ»ÐµÐ´ÑÑÑÐ¸Ðµ Ð²ÑÐ²Ð¾Ð´Ñ: ÐÐµÑÐ¾Ð´ ÐºÐ°Ð»Ð¸Ð±ÑÐ¾Ð²Ð¾ÑÐ½Ð¾Ð¹ ÐºÑÐ¸Ð²Ð¾Ð¹ ÑÐ¾ÑÐ¾ÑÐ¾ ÑÐ°Ð±Ð¾ÑÐ°ÐµÑ: Ð½ÐµÑ Ð¿ÑÐ¾Ð±Ð»ÐµÐ¼Ñ, ÑÐ²ÑÐ·Ð°Ð½Ð½Ð¾Ð¹ Ñ ÑÐ°Ð·ÑÐµÑÐµÐ½Ð¸ÐµÐ¼ Ð´ÐµÑÐµÐºÑÐ¾ÑÐ° Ð¢ÐµÐ¾ÑÐµÑÐ¸ÑÐµÑÐºÐ¸Ðµ ÑÐ¸ÑÑÐµÐ¼Ð°ÑÐ¸ÑÐµÑÐºÐ¸Ðµ Ð½ÐµÐ¾Ð¿ÑÐµÐ´ÐµÐ»ÐµÐ½Ð½Ð¾ÑÑÐ¸ Ð¿Ð¾Ð»ÑÑÐ¸Ð»Ð¸ÑÑ Ð½ÐµÐ±Ð¾Ð»ÑÑÐ¸Ð¼Ð¸: Ð¡Ð¸ÑÑÐµÐ¼Ð°ÑÐ¸ÐºÐ° ÐÐºÐ»Ð°Ð´ Ð² % PDFÂ 4.16 % ÐÐ°ÑÑÑÐ°Ð±Ñ Î¼_R Ð¸ Î¼_F 2.9 % ISR Î±_s 0.27 % ÐÐ°Ð½Ð½Ð°Ñ Ð¼ÐµÑÐ¾Ð´Ð¸ÐºÐ° (Ð¼ÐµÑÐ¾Ð´ ÐºÐ°Ð»Ð¸Ð±ÑÐ¾Ð²Ð¾ÑÐ½Ð¾Ð¹ ÐºÑÐ¸Ð²Ð¾Ð¹) Ð±ÑÐ´ÐµÑ Ð¸ÑÐ¿Ð¾Ð»ÑÐ·Ð¾Ð²Ð°Ð½Ð° Ð¿ÑÐ¸ Ð°Ð½Ð°Ð»Ð¸Ð·Ðµ Ð´Ð°Ð½Ð½ÑÑ ÑÐºÑÐ¿ÐµÑÐ¸Ð¼ÐµÐ½ÑÐ° ATLAS. Ð¡ÐµÐ¹ÑÐ°Ñ, Ð½Ð° Ð¾ÑÐ½Ð¾Ð²Ðµ Ð¿Ð¾Ð»ÑÑÐµÐ½Ð½ÑÑ ÑÐµÐ·ÑÐ»ÑÑÐ°ÑÐ¾Ð², Ð¿ÑÐ¾Ð²Ð¾Ð´ÑÑÑÑ Ð¸ÑÑÐ»ÐµÐ´Ð¾Ð²Ð°Ð½Ð¸Ñ ÐºÐ²Ð°Ð½ÑÐ¾Ð²Ð¾Ð¹ Ð·Ð°Ð¿ÑÑÐ°Ð½Ð½Ð¾ÑÑÐ¸ Ð¿ÑÐ¸ Ð¿Ð°ÑÐ½Ð¾Ð¼ ÑÐ¾Ð¶Ð´ÐµÐ½Ð¸Ð¸ t-ÐºÐ²Ð°ÑÐºÐ¾Ð². ÐÐ¸ÑÑÐµÑÑÐ°ÑÐ¸Ñ Ð²ÐºÐ»ÑÑÐ°ÐµÑ Ð² ÑÐµÐ±Ñ ÑÐ°Ð±Ð¾ÑÑ Ð¿Ð¾ Ð¼Ð¾Ð´ÐµÑÐ½Ð¸Ð·Ð°ÑÐ¸Ð¸ ÑÐ¸ÑÑÐµÐ¼Ñ Ð¾Ð¿Ð¸ÑÐ°Ð½Ð¸Ñ Ð³ÐµÐ¾Ð¼ÐµÑÑÐ¸Ð¸ ÑÐ¾Ð½ÐºÐ¾Ð·Ð°Ð·Ð¾ÑÐ½ÑÑ ÐºÐ°Ð¼ÐµÑ (Ð°Ð½Ð³Ð». Thin-gap chambers, TGC) Ð² Ð¿ÑÐ¾Ð³ÑÐ°Ð¼Ð¼Ð½Ð¾Ð¼ Ð¾Ð±ÐµÑÐ¿ÐµÑÐµÐ½Ð¸Ð¸ ATLAS muon system. ÐÐ¾Ð²Ð°Ñ ÑÐµÐ°Ð»Ð¸Ð·Ð°ÑÐ¸Ñ TGC Ð¿ÑÐµÐ´ÑÑÐ°Ð²Ð»ÐµÐ½Ð° Ð² Ð²Ð¸Ð´Ðµ Ð½Ð°Ð±Ð¾ÑÐ° XML ÑÐ°Ð¹Ð»Ð¾Ð². ÐÑÐ°ÑÐºÐ¾Ðµ Ð¾Ð¿Ð¸ÑÐ°Ð½Ð¸Ðµ ÑÑÐ¾Ð¹ ÑÐ°Ð±Ð¾ÑÑ Ð¸ ÐµÐµ ÑÐµÐ·ÑÐ»ÑÑÐ°ÑÑ Ð¾Ð¿Ð¸ÑÐ°Ð½Ñ Ð² 1 Ð³Ð»Ð°Ð²Ðµ Ð² Ð¿Ð¾Ð´Ð¿ÑÐ½ÐºÑÐµ 1.2.1.
description: The given work is devoted to methodological studies aimed at analyzing the spin correlations of t-quark-t-antiquark pairs, as well as the study of methods for detectorâs distortion elimination. The study of spin correlations of tt Ì quarks is important both for the refinement of the Standard Model and for the search for physics beyond the Standard Model. Considering the detector effects is necessary to restore the true distributions, which makes it possible to compare measurements with theoretical predictions. The aims of the work are to test one of the methods of detectorâs distortion elimination - the calibration curve method, as well as to evaluate various theoretical sources of systematic uncertainties. As a result of the work, studies of the spin properties of the t-quark were carried out using Monte Carlo simulation. Different Monte Carlo generators were used to simulate production pairs of t-quark-t-antiquark. Distributions were obtained from the variable cosâ¡(Ï_ll ) (where Ï_ll is the angle between two leptons in their respective parent tâquarks), from which the correlation coefficient D was calculated. In order to take into account, the detector effects the distributions were reweighted by the variable cosâ¡(Ï_ll ) at the âtruthâ level at various points: -60%, -40%, -20%, 0%. And an assessment of systematic uncertainties from various sources was carried out: the systematics ofÂ  parton distribution functions (PDF), the systematics of renormalization scales (Î¼_R) and factorization (Î¼_F), as well as the systematics associated with radiation in the initial state (ISR). The assessment of systematic uncertainty was carried out at each reweighing point. As a result, a region of systematic uncertainties was obtained for each calibration curve. The results of the analysis allow us to draw the following conclusions: Calibration curve method works well: no problem related to detector resolution Theoretical systematic uncertainties turned out to be small: Systematics Percentage effect PDF 4.16 % Scales of Î¼_R Ð¸ Î¼_F 2.9 % ISR 0.27 %. The results obtained will be used in the analysis of the data from the ATLAS experiment. Now, based on the results obtained, are being carried out studies of quantum entanglement in the pair production of t-quarks. This dissertation includes work related to the implementation of thin-gap chambers (TGC) in the ATLAS muon system software. TGCs are the main end trigger devices (in the range of pseudorapidity 1.05 &lt; |Î·| &lt; 2.4). Implementation of the TGC chambers is presented as an XML description. A brief description of this work and its results are described in chapter 1 in subsection 1.2.1.